islet amyloid polypeptide, islet amyloid, and diabetes mellitus

Transcription

Physiol Rev 91: 795– 826, 2011
doi:10.1152/physrev.00042.2009
ISLET AMYLOID POLYPEPTIDE, ISLET AMYLOID,
AND DIABETES MELLITUS
Per Westermark, Arne Andersson, and Gunilla T. Westermark
Departments of Medical Cell Biology and Immunology, Genetics and Pathology, Uppsala University, Uppsala,
Sweden
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VII.
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IX.
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XIII.
XIV.
INTRODUCTION
ISLET AMYLOID AND ISLET AMYLOID...
EXPRESSION OF ISLET ...
ORGANIZATION OF ISLET AMYLOID...
ISLET AMYLOID POLYPEPTIDE IN...
ISLET AMYLOID POLYPEPTIDE
RECEPTORS
PHYSIOLOGICAL AND...
ISLET AMYLOID POLYPEPTIDE...
PATHOGENESIS OF TYPE 2 DIABETES
ENDOPLASMIC RETICULUM STRESS...
AUTOPHAGY
AMYLOID FORMATION IN...
FUTURE RESEARCH
CONCLUSION
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I. INTRODUCTION
Islet amyloid polypeptide (IAPP), or amylin, was named for its
tendency to aggregate into insoluble amyloid fibrils, features
typical of islets of most individuals with type 2 diabetes. This
pathological characteristic is most probably of great importance
for the development of the ␤-cell failure in this disease (146, 171),
but the molecule also has regulatory properties in normal physiology. In addition, it possibly contributes to the diabetic condition. This review deals with both these facets of IAPP.
II. ISLET AMYLOID AND ISLET AMYLOID
POLYPEPTIDE: A SHORT HISTORY
Islet amyloid, initially named “islet hyalinization,” was described in 1901 by two researchers independently (282,
377) and for a long time was considered an enigma. It was
found to occur in association with diabetes mellitus, particularly in elderly individuals, but its possible pathogenetic
importance was often denied, since it was not found in all
individuals with diabetes (21, 93, 394). Moreover, islet hyalinosis is not unique for diabetes but is also observed in
nondiabetic individuals, although it then affects fewer islets
and to a lesser extent (22, 214, 394). The similarity of the
hyaline substance to amyloid was noted at an early date,
and some researchers reported staining reactions typical of
amyloid (6, 12, 114). Only later, however, was more general agreement reached about the amyloid nature of the islet
deposits (93, 324, 393). At that time this was not of great
help since the nature of amyloid in general was not understood. It had been shown in 1959 that amyloid of several
types has a characteristic ultrastructure (63), and islet deposits were found to share this appearance (196). When
biochemical analyses of amyloid fibrils from systemic primary and secondary amyloidoses showed that these consisted of distinctive proteins (23, 123), it was suspected that
the islet deposits might also be a polymerized protein.
The chemical composition of islet amyloid did not attract
much attention even after the characteristics of other amyloid fibrils had been elucidated. The finding that the amyloid in C cell-derived medullary thyroid carcinoma is of
polypeptide hormonal origin was an important indication
that amyloid in other endocrine tissues also comes from the
local secretory products (334), and it was believed that
insulin, or proinsulin, or split products thereof constitute
the islet amyloid fibrils (294). Immunological trials to char-
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Westermark P, Andersson A, Westermark GT. Islet Amyloid Polypeptide, Islet Amyloid, and
Diabetes Mellitus. Physiol Rev 91: 795–826, 2011; doi:10.1152/physrev.00042.2009.—
Islet amyloid polypeptide (IAPP, or amylin) is one of the major secretory products of
␤-cells of the pancreatic islets of Langerhans. It is a regulatory peptide with putative
function both locally in the islets, where it inhibits insulin and glucagon secretion, and at
distant targets. It has binding sites in the brain, possibly contributing also to satiety regulation and
inhibits gastric emptying. Effects on several other organs have also been described. IAPP was
discovered through its ability to aggregate into pancreatic islet amyloid deposits, which are seen
particularly in association with type 2 diabetes in humans and with diabetes in a few other
mammalian species, especially monkeys and cats. Aggregated IAPP has cytotoxic properties and
is believed to be of critical importance for the loss of ␤-cells in type 2 diabetes and also in pancreatic
islets transplanted into individuals with type 1 diabetes. This review deals both with physiological
aspects of IAPP and with the pathophysiological role of aggregated forms of IAPP, including
mechanisms whereby human IAPP forms toxic aggregates and amyloid fibrils.
WESTERMARK ET AL.
III. EXPRESSION OF ISLET
AMYLOID POLYPEPTIDE
IAPP is a 37-aa residue long peptide, but by the application
of molecular biological methods it was quickly shown that
IAPP is expressed initially as part of an 89-aa residue preproprotein containing a 22-aa signal peptide and two short
flanking peptides, the latter cleaved off at double basic aa
residues (28, 254, 268, 319) similar to proinsulin (272).
IAPP is expressed by one single-copy gene on the short arm
of chromosome 12, in contrast to insulin and the other
members of the calcitonin family, including CGRP, adrenomedullin, and calcitonin, all of which are encoded by
genes on the evolutionary related chromosome 11 (see Ref.
414 for review). The preproIAPP gene contains three exons,
of which the last two encode the full prepromolecule (55,
254, 269). The signal peptide is cleaved off in the endoplasmic reticulum (ER), and conversion of proIAPP to IAPP
takes place in the secretory vesicles. ProIAPP and proinsulin
are both processed by the two endoproteases prohormone
convertase 2 (PC2) and prohormone convertase 1/3 (PC1/3)
and by carboxypeptidase E (CPE) (FIGURE 1). This pHdependent processing takes place in the late Golgi and secretory granules. PC1/3 cleaves human proinsulin almost
exclusively on the carboxyl side of Arg31 Arg32 at the B/C
junction of proinsulin, whereas PC2 favors the Lys64
Arg65 site at the A/C junction (335, 336). The processing is
sequential and first occurs at the B/C junction. CPE removes
the COOH-terminal dibasic amino acids (74). PC2 processes proIAPP at position Lys10 Arg11, and PC1/3 at position Lys50 Arg51 (234). It has been shown that in the
absence of PC1/3, PC2 can process proIAPP at the COOHterminal processing site (371). As for many other hormonal
peptides, the COOH-terminal glycine residue is used for
FIGURE 1 A: the amino acid sequence of human pro-islet amyloid polypeptide (proIAPP) with
the cleavage site for PC2 at the NH2 terminus
and the cleavage site for PC1/3 at the COOH
terminus, indicated by arrows. The KR residues
(blue) that remain at the COOH terminus after
PC1/3 processing are removed by carboxypeptidase E. This event exposes the glycine residue
that is used for COOH-terminal amidation. Below
is a cartoon of IAPP in blue with the intramolecular S-S bond between residues 2–7 and the amidated COOH terminus. B: the amino acid sequence of human proinsulin with the basic residues at the B-chain/C-peptide junction and the
A-chain/C-peptide/junction indicated in blue and
the processing sites indicated by arrows. PC1/3
does almost exclusively process proinsulin at the
B-chain/C-peptide junction while PC2 preferentially processes proinsulin at the A-chain/C-peptide junction. The basic residues (RR) (position
31, 32) that remain at the COOH terminus of the
B-chain is removed by the carboxypeptidase CPE.
Below is a cartoon of insulin A-chain and B-chain
in red with intermolecular SS bonds between cystein residues 7 in the A and B chains, between
cystein residues at position 19 in the B-chain and
20 in the A-chain and the intermolecular SS bond
between cystein residues at position 6 and 11 of
the A-chain.
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Physiol Rev • VOL 91 • JULY 2011 • www.prv.org
acterize the amyloid yielded equivocal results, and purification of a major fibril protein was hampered by the much
greater insolubility of islet amyloid deposits compared with
most other amyloid forms (388), except the amyloid core in
Alzheimer’s plaques (236). Only when concentrated formic
acid was used on amyloid, extracted from an amyloid-rich
insulinoma, was it possible to purify the major fibril protein
and characterize it by NH2-terminal amino acid sequence
analysis, which very unexpectedly revealed a novel peptide,
not resembling any part of proinsulin but with partial identity to the neuropeptide calcitonin gene-related peptide
(CGRP) (405). Further characterization of the peptide purified from an insulinoma and from islet amyloid of human
and feline origin proved it to be a 37-amino acid (aa) residue
peptide. The peptide was initially named “insulinoma amyloid peptide” (405), later diabetes-associated peptide
(DAP) (64), and finally islet amyloid polypeptide (IAPP)
(404), or “amylin” (66). The designation IAPP will be used
in this review.
IAPP, ISLET AMYLOID, AND DIABETES MELLITUS
amidation, which, in addition to a disulfide bridge between
residues 2 and 7, is a prerequisite for full biological activity.
The removed C peptide from proinsulin and the two flanking peptides from proIAPP remain in the secretory granule,
resulting at exocytosis in release of equimolar concentrations of the removed peptides and their respective final hormonal product.
In addition to islet ␤-cells, IAPP is expressed in the ␦-cells in
rat and mouse; in the gastrointestinal tract of the rat,
mouse, cat, and human (248, 258, 260, 357); and in sensory
neurons in rats (259). IAPP is also expressed in sensory
neurons in mice, and IAPP null mice exhibit a reduced pain
response in the Formalin paw test (113). In the gastrointestinal tract of rats, IAPP has been identified from the pyloric
antrum to the large intestine, with the highest concentration
in the antrum (248). However, on a weight basis, the
amount of pyloric IAPP was just 1% of that in the pancreas
(248). In the chicken, IAPP is mainly expressed in the brain
and in the intestine and to a much lower extent in the
pancreas (105). How synthesis, storage, and release are regulated at these extrapancreatic sites is unknown. Gene analysis of chicken proIAPP showed that the NH2-terminal
flanking peptide consists of 55 aa residues, considerably
longer than the 9 –12 residues reported in mammals (105),
probably pointing to a common ancestor of the IAPP and
CGRP genes.
It is more probable that IAPP is protected from aggregation
by interaction with other components. Plausible candidates
are proinsulin, insulin, or their processing intermediates.
Insulin has been found to be a strong inhibitor of IAPP fibril
formation (402). This finding has been verified in a number
of subsequent studies, which have also shown the potency
of the inhibition (157, 158, 195, 199, 326). The inhibition
seems to depend solely on the B-chain, which binds specifically to a short segment of IAPP (119). An insulin-to-IAPP
ratio of between 1:5 and 1:100 had a strong inhibitory
effect (199). The molar ratio between IAPP and insulin in
the granule as a whole is ⬃1–2:50, but the concentrations in
the halo region are not known. The possibility cannot be
ruled out, therefore, that even minor changes in the relative
proportions of IAPP and other halo components can initiate
aggregation and start fibril formation. The finding of amyloid-like fibrils in ␤-cell granules early in amyloidogenesis
(see below) may support this assumption (290).
Additionally, careful semiquantitative light and electron
microscopical analyses have revealed that whereas the insulin content is evenly distributed among the islet ␤-cells,
there is a much more pronounced heterogeneity concerning
the content of IAPP (292) (FIGURE 2). For instance, in the
islets of two human nondiabetic individuals, there was a
population of ␤-cells containing much more IAPP. This may
indicate that the relative proportions of IAPP and insulin
vary considerably between and perhaps within the cells.
Subtle changes in single cells may constitute the starting
point for fibril formation.
IV. ORGANIZATION OF ISLET
AMYLOID POLYPEPTIDE IN
SECRETORY VESICLES
V. ISLET AMYLOID POLYPEPTIDE IN
PLASMA AND PANCREAS
The crystalline structure of insulin in granules is well characterized (88). Hexameric insulin, together with zinc, constitutes the core of the mature granules, while IAPP, to-
IAPP purified from human pancreas and plasma has been
shown to have a composition identical to that of the amyloid protein (264). In addition, a peptide consisting of po-
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IAPP and insulin genes contain similar promoter elements
(117), and the transcription factor PDX1 regulates the effects of glucose on both genes (116, 280, 375). Glucose
stimulated ␤-cells respond with a parallel expression pattern of IAPP and insulin in the rat (173, 257). However, this
parallel secretion of IAPP and insulin is altered in experimental diabetes models in rodents. Perfused rat pancreas
secreted relatively more IAPP than insulin when exposed to
dexamethasone (275), whereas high doses of streptozotocin
or alloxan reduced insulin secretion more than that of IAPP
(256). Oleat and palmitate increased the expression of IAPP
but not of insulin in MIN6 cells (304). In mice fed a diet
high in fat for 6 mo, plasma IAPP increased 4.5 times more
than insulin compared with mice fed standard food containing 4% fat (383). In human recipients who had become
insulin-independent by intrahepatically transplanted islets,
there was disproportionately more IAPP than normal secreted during hyperglycemia (308). These examples show
that the strictly parallel expression of IAPP and insulin may
be disturbed under certain conditions.
gether with a large number of additional components, including the C peptide, is found in the halo region (402). The
highly fibrillogenic human IAPP (1) has to be protected in
some way from aggregation, which otherwise would take
place spontaneously. The fact that very fibril-prone proteins
can be kept in solution at high concentrations is known
from studies of arthropod silk (29). The composition of the
␤-cell granule is extremely complex, and it has many components in addition to insulin and C peptide (150), in micromolar concentrations (148). The intragranular pH has
been estimated to be 5– 6, close to the isoelectric point of
insulin (149), but this is favorable for the solution of the
basic molecule IAPP. It has recently been proposed that
polypeptide hormones are packed in granules with an amyloid-like conformation (“functional amyloid”) (225).
However, this is very unlikely, at least with human IAPP,
which forms unusually insoluble material when assembled
into amyloid fibrils (388).
WESTERMARK ET AL.
sitions 17–37 of IAPP was identified at both locations.
There seems to be no report on the possible function of this
fragment, but it should be noted that IAPP8 –37 is a IAPP
antagonist (373). The human plasma IAPP concentration is
only 1–2% of that of insulin. Since IAPP is costored with
insulin in the secretory vesicles (164, 216), a regulated cosecretion should occur and has in fact been demonstrated
(172). On glucose stimulation, the IAPP concentration
changes in parallel with that of insulin (51, 177, 257).
Like the C peptide, IAPP is eliminated in the urine (202), but
there are alternative degradation systems. Insulin-degrading enzyme (IDE, also known as Insulysin and insulinase;
Ref. 16) is a Zn2⫹-metalloprotease involved in the clearance
of insulin (92). IDE is present in the cytosol (16, 322),
peroxisomes (253), mitochondria (207), endosomes (89),
and on the cell membrane (124) of a wide variety of cells.
IDE lacks a signal peptide but is known to be secreted from
different cells, and its release has been shown to be unaffected by known stimulators of protein secretion. Therefore, the secretion is believed to be through an unconventional pathway that still needs to be elucidated (82). IDE
has also been shown to degrade A␤-peptide, and a missense
mutation in the IDE gene in the Goto-Kakizaki (GK) rat, a
well-characterized rat model of type 2 diabetes, reduces the
catalytic efficiency of the enzyme and affects the degradation of both insulin and A␤ (106). Overexpression of IDE in
A␤ precursor transgenic mice markedly reduces amyloid
plaque formation (206). IDE has also been shown to be
important for IAPP degradation (24), and incubation with
the IDE inhibitor bacitracin impairs degradation of IAPP
and increases IAPP cytotoxicity and the deposited amyloid
load (25).
A second protease capable of degrading amyloid is neprolysin (210), and this was also first shown to degrade
A␤1– 42 in vivo (426). Neprilysin is a type II zinc-containing metalloprotease with a short 23-residue NH2-terminally located intracellular domain, a 24-residue transmem-
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brane spanning domain, and a 699-residue catalytic extracellular domain (229). Viral overexpression of neprilysin in
presynaptic sites leads to a pronounced deceleration of A␤
amyloid accumulation in mutant A␤ precursor expressing
mice (251). Neprilysin is also present in islet cells, including
␤-cells, and its expression is normally reduced during aging.
Human IAPP-expressing mice, which are prone to develop
islet amyloid during ageing, display sustained elevation of
neprilysin mRNA with preserved activity. This indicates
that the islet neprilysin has a compensatory mechanism
aimed to prevent amyloid accumulation (447). In a recent
paper it was stated that neprilysin does not degrade IAPP,
but it is suggested that the protease directly interferes with
the fibril propagation (445).
VI. ISLET AMYLOID POLYPEPTIDE
RECEPTORS
The calcitonin peptide family members act through seven
transmembrane domain G-coupled receptors. As a hormone, IAPP should have specific receptors, but efforts to
find such receptors were long in vain, although specific
binding sites were identified, particularly in the brain (293,
328) and renal cortex (418). The failure to find receptors
was explained by the discovery of a family of receptor activity-modifying proteins (RAMPs), which are single-domain proteins (241). Three different RAMPs were identified
(241). They are not receptors in themselves, but when they
dimerize with the calcitonin receptors, they interact and
alter the affinity for ligands (435). When the calcitonin receptor forms complexes with one of the RAMPs, the receptor affinity may change, and certain combinations create
high-affinity IAPP receptors (255, 302, 354). In this way,
several IAPP receptors may form (57, 134, 252). This novel
principle has so far been recognized only within the calcitonin family. Expression of RAMPs and calcitonin receptors has been identified in areas of the mouse and rat brain
that can be reached by circulating IAPP (19, 363). Both
FIGURE 2 The immunolabeling patterns for insulin and IAPP in normal human islets vary. Insulin labeling is
evenly distributed, while that of IAPP varies in intensity between cells. Measurements of optical density show
a negatively skewed distribution for both hormones, but the IAPP measurement also shows a minor population
of cells with maximal labeling (arrow). This shows that normal human islets contain a small fraction of cells with
a high IAPP content. The intensity of optical density was measured and graded from 255 to 0, where 255
corresponds to maximal labeling and 0 to unlabeled areas. [Modified from Paulsson and Westermark (292).]
calcitonin receptors and RAMPs have been demonstrated in
a ␤-cell line (231). The RAMPs seem to act by several mechanisms. For example, they participate in transport of receptor protein to the cell surface, influence glycosylation (241),
and modulate signaling (252).
VII. PHYSIOLOGICAL AND
PATHOPHYSIOLOGICAL EFFECTS OF
ISLET AMYLOID POLYPEPTIDE
A. General Considerations
The function of IAPP is not fully understood. One major
problem is the difficulty in differentiating between its physiological or pathophysiological role and its pharmacological effects achieved experimentally. This cannot always be
done. IAPP is costored with insulin in the secretory vesicles,
and it is reasonable to believe that it is involved in the
regulation of glucose metabolism. Very early after the discovery of IAPP, it was found that the peptide inhibits insulin-stimulated glucose uptake and glycogen synthesis in isolated incubated rat skeletal muscle (66). This inhibition may
be mediated by effects on several enzymes (79). It was also
shown that IAPP inhibits insulin-stimulated glucose transport in vitro by a post-insulin-receptor effect (444). It was
initially hoped, therefore, that the mechanism underlying
insulin resistance in type 2 diabetes had been found with the
discovery of IAPP, and it was shown that insulin resistance
Nowadays, there are two plausible physiological roles of
IAPP that are of particular interest. One is its function as an
auto- or paracrine molecule in the islets of Langerhans, and
the other is its role as a hormone with effects on the central
nervous system.
B. IAPP Effects on Cells in the
Islets of Langerhans
In vivo, in humans, only a very high plasma concentration
(2,240 but not 1,420 pM) of IAPP, much above what is
found under physiological conditions, has been reported to
affect the insulin response to a glucose load. At this very
high plasma concentration both the first and second phase
of the insulin response was depressed (34). Studies on in
vitro effects of IAPP on insulin secretion have yielded contradictory results. Several investigators, for example, have
reported an inhibition of insulin secretion (81, 191, 318,
442), even at as low a concentration as 75 pM in the perifused rat pancreas (331). On the other hand, others have
reported no inhibitory effect of IAPP on insulin release (35,
279, 296). For further reading on this matter, see Reference
432. So far, there is no definite explanation for these varying results, but at early dates the strong tendency for human
IAPP to aggregate into amyloid-like fibrils was not taken
FIGURE 3 The amino acid sequences of proIAPP of some mammalian species with numbering according to
the human sequence. IAPP is strongly conserved but with notable variation in the 20 –29 region of IAPP. This
corresponds to residues 31– 40 of proIAPP. This important area is highlighted with a red box. Species without
occurrence of islet amyloid dog, rat, mouse, guinea pig, degu, and cow have one or more proline residues at
this region. Proline residues 36 and 39 are believed to be essential for inhibition of aggregation.
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The phylogenetically conserved nature of IAPP (FIGURE 3)
indicates an important function. On the other hand, the two
flanking peptides show a much higher degree of amino acid
substitution (FIGURE 3). This may be taken to indicate that
they do not have regulatory functions, and no such functions seem to have been described. On the other hand, the
same has been claimed for the proinsulin C peptide, which
today has been shown to have putatively important physiological effects (98, 130, 345, 368). The possible effects of
the two IAPP flanking peptides have not been studied.
could be induced by infusion of IAPP in vivo (166). However, these effects were achieved at concentrations much
higher than those seen physiologically and were therefore to
be regarded as pharmacological rather than physiological.
Increased plasma IAPP concentration in association with
renal insufficiency had no effect on insulin secretion (215).
However, the possible role of IAPP in the modification of
insulin effects on peripheral tissues is still controversial, and
it cannot be excluded that IAPP has an important function
in the fine tuning, that is difficult to demonstrate experimentally. These effects, and possible effects, direct or indirect,
on the liver and adipose tissues have been reviewed several
times (59, 65, 401, 414) and will not be repeated here in
detail.
WESTERMARK ET AL.
Very different results have been obtained concerning the
effect of IAPP on glucagon secretion. Silvestre et al. found
no direct IAPP effect on glucagon cells, but their results
indicated possibly centrally mediated inhibition of glucagon release by arginine (332). Likewise, Young (434) reported that IAPP had no effect on hypoglycemic stimulation
of glucagon secretion. On the other hand, other studies,
conducted on isolated mouse islets, have shown an inhibitory effect of IAPP on glucagon secretion (8, 285). The
addition of IAPP 8 –37, which is an antagonist of IAPP, or
immunoneutralization of the endogenous IAPP secretion in
cultured rat islets, resulted in a dose-dependent increase in
stimulated insulin and glucagon secretion. There were no
effects, however, on basal insulin secretion (370).
In summary, there are many studies which indicate a paraor autocrine function of IAPP, but the mechanisms are still
far from clear.
C. Anorectic Effects and Influence on
Gastric Emptying
The inhibitory effect of IAPP (including pharmacological
analogs) on eating has been well established in experimental animals and in humans (13, 18, 217, 218). In a
study on healthy men, it was found that the drug “pramlintide” (essentially human IAPP with amino acid substitutions altering its solubility) reduced the caloric intake
as well as the meal duration (48). Binding sites for IAPP
have been found at several locations in the brain, including the nucleus accumbens and the area postrema (56), of
which at least the latter is outside the blood-brain barrier, making it a possible target for IAPP produced by the
islets of Langerhans. However, although it was initially
stated that there is no cerebral production of IAPP, several later studies have demonstrated IAPP immunoreactivity (69, 70, 333) in the hypothalamus and basal ganglia. IAPP mRNA was also identified in the preoptic area
of the lactating rat (85). Furthermore, IAPP and IAPP
800
mRNA have been found in the human brain (G. T.
Westermark and M.E. Oskarsson, unpublished results).
It is still not known whether or not IAPP expressed intracerebrally is of importance for food intake or gastric
emptying.
Like cholecystokinin, IAPP also inhibits gastric emptying
(307), but while the former seems to act through afferent
vagus nerve fibers, IAPP does not (408) and elicits its effects
by binding to the brain (13). Gastric emptying is pathologically rapid in type 1 diabetes, and this is considered to be
one contributing cause of the postprandial hyperglycemia
in this disease (415). It is believed that the almost total lack
of islet IAPP production in type 1 diabetes may be pathogenically important in the gastric behavior (415). Inhibition
of gastric emptying and the underlying mechanisms of this,
particularly with emphasis on the IAPP analog pramlintide,
have recently been extensively reviewed (433).
D. Additional Effects of IAPP
The structural similarity of IAPP to calcitonin immediately created interest in the possibility that IAPP may be
involved in the regulation of calcified tissues (222), and
experimentally it was shown that the peptide inhibits
osteoclastic activity (437). Many effects have been ascribed to IAPP, and today there is evidence to indicate
that the hormone plays a physiological role in inhibition
of bone resorption (for review, see Ref. 266).
IAPP has an effect as vasodilator but is two orders of magnitude less effective than its relative CGRP (32, 111). This
vasodilative property of IAPP probably depends on binding
to CGRP receptors.
Early binding studies revealed strong binding of radiolabeled IAPP to the renal cortex (346). This was regarded as
unspecific uptake of radioactivity due to reabsorption of
labeled IAPP in the proximal tubules, but later studies have
indicated specific binding (418). A physiological effect on
the renin-angiotensin system has been suggested (417).
VIII. ISLET AMYLOID POLYPEPTIDE
AND AMYLOID
A. What Is Amyloid?
Amyloid is a generic term for a specific protein aggregation state in which molecules in ␤-sheet conformation are
bound to each other predominantly by hydrogen bonds
but also by other bonds (87, 121, 122, 310). This state of
aggregation creates thin (⬃10 nm), stable fibrils in which
the ␤-strands are oriented perpendicular to the fibril axis.
In humans, more than 25 proteins are known to create
amyloid fibrils, and more will be described (390, 396).
into consideration (432) and the reported effects of early
IAPP preparations may be questioned. Today there are effective methods of synthesizing pure and fully active IAPP
(4, 140). Interestingly, in addition, Åkesson et al. (8) found
that IAPP may have dual effects on insulin release, with
stimulation of basal insulin secretion and suppression under
conditions of enhanced insulin secretion. It is of interest that
male IAPP knock-out mice showed increased insulin responses paralleled with more rapid blood glucose elimination compared with wild-type controls (112). These findings indicate that endogenous IAPP has a physiological role
for and suggest that IAPP limits the degree of glucose-induced insulin secretion and the rate of blood glucose elimination (62). In accordance with this notion, Ahrén et al. (5)
observed the opposite effect in human IAPP transgenic
mice.
Not only IAPP but also several other polypeptide hormones
can be deposited as amyloid, and this is a common finding in
endocrine tumors (400). Interestingly, insulin is also an islet
amyloid fibril protein; this does not occur spontaneously in
humans, but has been demonstrated in the hystricomorph rodent degu (137). The association of insulin-derived islet amyloid with diabetes in the degu strongly supports the importance of islet amyloid in human type 2 diabetes. In humans,
insulin can aggregate into an iatrogenic form of amyloidosis at
the sites of injections (84, 347, 436).
B. Islet Amyloid Formation
and Animal Species
As expected for a polypeptide hormone, IAPP is conserved through evolution, and the molecule has been
characterized in mammals, birds, and teleostean fishes
(168, 230, 247, 268, 381). In particular, the NH2- and
COOH-terminal parts of IAPP are conserved (FIGURE 3).
The pathological deposition of IAPP-derived amyloid in
the islets of Langerhans occurs not only in humans but
also in some other mammalian species. One important
reason for the earlier relative lack of interest in islet amyloid
may be the fact that it does not occur in the animals commonly
used in diabetes research, such as the rat and mouse (401). Rat
and mouse IAPP (which are identical) lack fibrillogenicity in
vivo and in vitro. The reason for this is to be found in differences in the primary structure. Although IAPP is a conserved
molecule, there is an interspecies variation at some critical amino acid residues. Most obvious are the variations
detected in the IAPP20 –29 region, where five out of six
differences between rat and human IAPP are found (FIGURE 3). Notably, rat/mouse IAPP has three proline residues, known as ␤-sheet breakers, in this region. Whereas
synthetic human IAPP20 –29 is extremely fibrillogenic,
the corresponding rat peptide is not (398). The rat shares
this sequence characteristic with several rodents, while
species with amyloidogenic IAPP include humans, non-
human primates, and cats (26, 27). These differences
only explain why amyloid can develop, not why it does.
Later studies have indicated that although the IAPP20 –29
region is essential to amyloid formation, other parts of the
molecule are also important in fibrillogenesis (2, 125, 155,
192, 267). The IAPP14 –20 domain, which is within the
amphipathic helical region of the molecule (265), may be of
particular importance (118) (see below). It has been suggested that the structure of IAPP in the amyloid fibril form
may be a double ␤-hairpin (␤-serpentine) with three
␤-strands consisting of residues 12–37 (175) (FIGURE 4, A
AND B). These are then stacked and held together by Hbonds with the NH2-terminal part sticking out from the
core (FIGURE 4C) (175). In another model, partially based
on X-ray crystallography of short IAPP segments, the
basic unit is a hairpin, allowing interaction between
Phe23 and Tyr37 (412), which is in agreement with data
from fluorescence resonance energy transfer (FRET)
(284). A solid-state NMR study resulted in a similar although not identical model (213) (FIGURE 5). Based on
results with additional methods, Dupuis et al. (91) concluded that the ␤-hairpin structure is the direct amyloid
fibril precursor. The pathological aggregation may be
initiated in the helix region with conversion into ␤-sheet
structure and may be catalyzed by membranes (3, 190,
265). Results of a recent study indicated that human
IAPP dimerizes when in a high degree of ␣-helical state
(413). This dimer is an on-pathway intermediate in the
fibril formation.
C. The Three-Dimensional Structure of IAPP
and Amyloid Formation
The 37-amino acid residue peptide IAPP belongs to the
calcitonin family, which also contains calcitonin, CGRP,
adrenomedullin, and intermedin (312, 414). Human
IAPP has 43– 46% identity with the two CGRPs (404).
IAPP shares with the other peptides in the family a disulfide bridge between amino acid residues 2 and 7 and an
amidated COOH terminus, which are posttranslational
modifications important for biological function. IAPP
has more limited sequence identity with other members
of the CGRP family (414). IAPP has been mentioned as
having a random coil structure (179). However, both CD
(190) and NMR studies (265, 288, 411) have shown that
the peptide forms an at least transient amphipathic helix
in the NH2-terminal region (3), except for the very NH2terminal part, which forms a rigid ring structure, resulting from the disulfide bridge between residues 2 and 7. In
solution, the helix spans residues 5–23 (190). The
COOH-terminal part of the molecule is unstructured
(265). The helical part is believed to be important in
receptor binding and may also be deeply involved in the
pathological transformation to amyloid fibrils (see below). The quaternary structure of human and rat IAPP is
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Most of them are not related, and at present it is not
known why only certain proteins aggregate in this form.
Polypeptide hormones are overrepresented (379), possibly because of their small size, their low degree of native
secondary structure, and their local occurrence at high
concentration. Many small peptides and proteins are able
to create fibrils in vitro with amyloid-like properties (86,
310). However, the designation amyloid should be reserved for the material deposited in vivo which, in addition to its fibril core protein, has components including
proteoglycans and usually the glycoprotein serum amyloid P component (396). Thus fibrils made in vitro are not
amyloid but “amyloid-like” (39). The aggregation state
of the fibrils creates properties by which amyloid is recognized, including typical reactions with certain dyes
such as Congo red, a fine fibrillar ultrastructure, and a
characteristic X-ray diffraction pattern (122).
WESTERMARK ET AL.
essentially the same, but with some important differences
depending on the presence of three proline residues in the
rat sequence. These differences make human but not rat
IAPP amyloidogenic.
D. Impact of Islet Amyloid
The development of islet amyloid is difficult to study in
humans. Islet amyloidosis associated with diabetes much
FIGURE 5 The 3-dimensional structures of human
IAPP1–19 (A), human IAPP (B), rat IAPP (C), and rat
IAPP1–19 (D) were determined in the presence of dodecylphosphocholine (DPC) micelles. The structure of
rat IAPP consists of an NH2-terminal helical region spanning residues 5–23 and a flexible COOH-terminal region.
The structure of human IAPP resembles rat IAPP with
an ordered helical structure at the NH2 terminus and a
distorted COOH-terminal region. The NH2-terminal region in human IAPP is more flexible and is embedded
deeper into the membrane. This location is more favorable for aggregation leading to membrane destruction.
The hydrophobic residues that have been implicated in
coiled-coil interactions (blue) stabilize the IAPP oligomer.
[From Nanga et al. (265), with permission. Copyright
2009, American Chemical Society.]
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FIGURE 4 A and B: a proposed model of human IAPP in
its amyloid ␤-serpentine fold with three ␤-strands assigned to residues 12–17, 22–27, and 31–37. The
strands are linked by a 4- and a 3-residue turn, respectively. The 11 residues at the NH2 terminus that contains
the disulfide bond do not participate in the stacking of the
monomer. C: stereo view of the protofilament model of
human IAPP. The monomers are assembled in a parallel
manner with the NH2-terminal extension aligned in one
direction and the structure is supported by H-bonds.
Stacking of monomers results in a left-handed twist of 1°
per subunit. [From Kajava et al. (175), with permission
from Elsevier.]
Important information on the impact of IAPP aggregation
for the development of diabetes has come from studies with
animals, transgenic for human IAPP. A number of transgenic mouse strains have been developed, usually with human IAPP cDNA placed behind the rat insulin I or II promoter (68, 110, 151, 240, 420). Also, a transgenic rat expressing human IAPP behind the rat insulin II promoter
(HIP rat) has been created (38). The phenotypes have varied
(240), but in several strains diabetes has developed in association with the development of islet amyloid and loss of
␤-cell mass, comparable to events in human type 2 diabetes
(160, 239, 339). In some mouse strains, a diet high in fat or
induction of insulin insensitivity has been necessary for the
creation of the diabetic phenotype (152, 367). Hemizygous
HIP rats became diabetic with pronounced islet amyloidosis. In addition to the support for an important role of IAPP
aggregation in the pathogenesis of the ␤-cell lesion coming
from studies of transgenic animals, inhibition of proIAPP
expression by small interfering RNA (233) as well as treatment with a peptide inhibitor of IAPP aggregation (301)
enhanced ␤-cell survival in cultured human islets. Taken
together, all these studies firmly corroborate the impact of
aggregated IAPP in the pathogenesis of type 2 diabetes.
Islet amyloidosis is commonly found in ageing animals of
the hystricomorph rodent degu (Octodon degus), living in
South America (343). Interestingly, in this species the amyloid fibril is made up of insulin (137), which in this group of
animals has certain peculiar characteristics (137, 270). The
degu IAPP is not, however, amyloidogenic (270) (FIGURE 3).
IX. PATHOGENESIS OF TYPE 2 DIABETES
A. Insulin Resistance and ␤-Cell Function
The pathogenesis of type 2 diabetes is complex and multifactorial and a subject of continuous intense investigation
(80, 107, 351). It seems clear today that two main factors,
each based on a number of different mechanisms, are involved (170, 174). One is a decreased effectiveness of insu-
lin (“insulin resistance”), leading to an increased demand
for the hormone, and the second main factor is the pancreatic ␤-cell failure. This includes a reduction both in the
␤-cell mass (61, 188, 314, 399) and in the ␤-cell function
(169). Similar findings have been described in a cat model of
type 2 diabetes (277). Also the baboon (Papio hamadryas)
is a very promising model of type 2 diabetes, including
development of islet amyloid (49, 127).
B. Function of Islets From Type 2
Diabetic Individuals
Direct studies of the function of islets from individuals with
type 2 diabetes are sparse. In an interesting study by Deng et
al. (83), islets isolated from patients with type 2 diabetes
showed inferior insulin secretion compared with matched
controls and failed to make diabetic recipient animals normoglycemic after transplantation. Notably, the glucagon
response was normal in perifusion experiments (83). A concern in this study, however, is the finding that islets purified
from diabetic donors were smaller than those from the controls, which is not a general observation in histological
studies (61, 223). The authors also state that there was very
little amyloid in the diabetic specimens and none in the
controls. Knowing the difficulty in finding the small, but
widely spread amyloid deposits in almost all diabetic pancreata, it seems very likely that amyloid was indeed present
and played a role in the failure of the islets.
C. Association of Islet Amyloid
With Diabetes
Islet amyloid is clearly linked to type 2 diabetes (21, 61, 93,
394) but also occurs in nondiabetic individuals, although it
then usually affects fewer islets and to a less severe degree
(22, 394). The facts that islet amyloid could be found in
some individuals without diabetes, that the depositions
were not pronounced in all diabetic pancreata, and that
well-granulated ␤-cells were seen in islets with a large
amount of amyloid led to the somewhat premature conclusion some decades ago that islet amyloid is of no major
importance. Careful analyses showed, however, that amyloid deposition is associated with a reduced islet volume due
to a reduction of the ␤-cell mass (61, 399, 406). However,
the volume reduction in itself should hardly be an explanation for the insufficient insulin response in type 2 diabetes. It
was pointed out at an early date that ␤-cells in the proximity
of amyloid were penetrated by bundles of fibrils, ending
deep in the cells (391). It is reasonable to believe that the
function of such cells is disturbed. Interestingly, new knowledge indicates that interactions between amyloid fibrils and
the cell membrane can lead to unregulated Ca2⫹ influx,
which would seriously affect the function of the cells (178).
It is claimed that in type 1 diabetes clinical symptoms show
up when the ␤-cell mass is reduced to 10% of the normal. In
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resembling the human type 2 form occurs in the domestic
cat and in several monkey species (75, 143, 167). Careful
studies by Johnson et al. in domestic cats (163, 277, 278),
by Howard in black Celebes monkeys (143, 144), and recently by Guardado-Mendoza et al. in baboons (127) have
revealed evidence of the importance of islet amyloid for the
diabetic state, indicating that the deposits are not only the
result of the disease. The latter authors conclude: “Whether
islet amyloid (IA) is a cause or consequence of ␤-cell dysfunction/hyperglycemia is controversial, but we believe that
IA plays a causative role in the ␤-cell dysfunction/apoptosis
that is observed in T2DM in a manner that is similar to
other human diseases that are associated with amyloid deposits, causing dysfunction of the affected tissue and organs” (127).
WESTERMARK ET AL.
a recent study it was shown that in this disease, also, individual islets may still contain a considerable number of
insulin-containing cells (410). Likewise, islets with amyloid
in type 2 diabetes contain ␤-cells filled with insulin granules
(391). This does not mean, however, that the islets function
normally (406).
D. IAPP Gene Mutations, Type 2 Diabetes,
and Islet Amyloid
In a larger Japanese study, the IAPPS20G frequency was 40
of 1,538 among diabetic subjects and 9 of 1,108 among
nondiabetic controls (325). Furthermore, Lee et al. (204)
identified 7 of 462 Chinese type 2 diabetic patients with the
mutation but no individuals with the mutation in a control
population of 126 persons. In the same way as in the first
study (316), the majority had developed type 2 diabetes at a
comparatively young age. On the other hand, in three other
reports, one from Japan (422), one from China (58), and
one from Korea (53), the mutation showed no association
with diabetes. The studied series were relatively small, however. IAPPS20G has only been identified in Asian populations and not in Caucasians or Mexicans (273).
There is one more reported mutation in the IAPP gene leading to an amino acid substitution (IAPPQ10R); this was
It is obvious that the IAPPS20G mutation plays no major
role in the pathogenesis of type 2 diabetes. It is reasonable
to believe that IAPPS20G constitutes a risk factor for the
disease, the nature of which is not known at present. Position 20 lies within the most amyloidogenic part of IAPP
(398), but other parts of IAPP may also contribute to fibrillogenesis (2, 118). IAPPS20G exhibited increased fibrillogenicity in vitro compared with the wild-type protein (221,
315). As a result of the mutation there is a decreased entropy cost in the assembly process, which may explain the
increased amyloidogenicity (419). Insulin has been reported
to inhibit fibril formation of both IAPP variants, but there
was a tendency towards less effective inhibition with the
mutant protein (221). Hypothetically other common risk
factors leading to ␤-cell dysregulation may cause enhanced
amyloid formation in individuals with the IAPPS20G mutation.
E. Islet Amyloid Formation: Intraor Extracellular?
Typical of the deposits seen in the human type 2 diabetic islet
is their extracellular location, even when small (FIGURE 6A).
When the amount of amyloid increases, the number of endocrine cells, particularly ␤-cells, is reduced. In spite of this,
there is evidence that IAPP aggregation starts intracellularly. The problem is certainly not only an academic one but
may have fundamental consequences both for the mecha-
FIGURE 6 A: human pancreatic islet with extracellular amyloid deposits, a typical finding in type 2 diabetes.
The section is stained for amyloid with Congo red. B: electron micrograph of a part of a ␤-cell with intracellular
amyloid. Note the thin amyloid fibrils within the membrane-encircled compartments (black arrow). Amyloid
between two cells is indicated by red arrows. C: electron micrograph of ␤-cell granules from human IAPP
transgenic mouse fed a diet high in fat. Intragranular fibrils present in the halo region are immunolabeled with
proIAPP specific antibodies (red arrows).
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In 1996, Sakagashira et al. (316) described a mutation in
the IAPP gene found in 12 of 294 individuals with type 2
diabetes. The mutation was not found in type 1 diabetic
patients or healthy controls. The missense mutation at
amino acid position 20 created a glycine-for-serine substitution of mature IAPP. In another study of 308 Japanese
individuals with late-onset type 2 diabetes, the mutation
was found in three patients as well as in 1 of 149 controls
(135).
found in a single type 2 diabetic Mauri patient (298). The
mutation was not seen in any of the 258 controls. In addition, there are at least two other mutations associated with
type 2 diabetes, which have been identified in the promoter
region of the IAPP gene (274, 298). The functional significance for the development of diabetes is, however, unclear
(103).
nisms by which aggregated IAPP affects the ␤-cells and for
the way in which therapeutic interventions can act on the
aggregation process.
With the transgenic technique, different strains of human
IAPP-expressing mice were developed in the early 1990s
(68, 110, 420). Even though islet amyloid did not occur
spontaneously after establishment of these strains, reports
on islet amyloid appeared not long after (160, 367). Early
histological studies on islet amyloid in autopsy specimens
indicated that all deposited material was extracellular, and
the same was also true for other types of amyloid (391).
However, when islet amyloid was studied in systems in
which amyloid develops more rapidly such as isolated human islets transplanted into mice, or transgenic mice expressing human IAPP, initial intracellular deposition became evident (156, 160, 290, 382, 387, 397, 421). Similarly, in other fast-forming amyloid systems, ␤-cell tumors
(insulinomas), evidence of intracellular fibrillogenesis was
obtained (276). Also in type 2 diabetic baboons, amyloid
was found both extracellularly and within ␤-cells (120).
The exact location of the intracellular amyloid has been
difficult to determine. O’Brien et al. (276) noted fibrillar
material free in the cytoplasm, without any surrounding
membrane, as well as some membrane-bound aggregates.
Both extra- and intracellular amyloid was found in type 2
diabetic baboon islets (127). In human islets transplanted
into nude mice or cultured in vitro, early amyloid forms an
intracellular network, indicating its presence within the ER
(FIGURE 6B) (290, 397). In addition, however, tiny intragranular IAPP-immunoreactive fibrils were observed at an
early phase of amyloidogenesis (290, 421) (FIGURE 6C). The
most likely sites for their development are in the ER, Golgi,
and secretory granules.
In amyloidogenesis in general, the molecules deposited in
the fibrils have undergone some degree of proteolysis, and
only rarely are unprocessed proteins found (77, 102, 243).
In the early phase of type 2 diabetes, disproportionately
We have put forward the following hypothesis for the initiation of amyloid formation in an islet (FIGURE 7). The very
first amyloid forms within single ␤-cells, perhaps from insufficiently processed proIAPP (290). This leads to the
death of the cell, now leaving a small extracellular amyloid
particle. This acts as a seed for secreted mature IAPP, which
adds progressively and forms the extracellular amyloid
masses that are typically seen in type 2 diabetes. A primary
defect in the prohormone processing machinery has been
suggested as part of the pathogenesis of type 2 diabetes
(154).
F. Amyloid Fibrils in the Secretory Granules
In transmission EM analysis of ␤-cells from hIAPP transgenic mice, amyloid deposits appeared to a varying degree,
and some cells contained only minute amounts of fibrillar
material. This was then present as fibrils in the halo region
of the secretory granules (FIGURE 6C). The fibrils were recognized by antibodies raised against the NH2-terminal and
COOH-terminal processing sites of proIAPP (290). Hence,
the secretory granule is a putative compartment for initial
fibrillogenesis, and at this location proIAPP may participate
in the process. There can be multiple reasons for the increase in secretion of proinsulin and/or proinsulin processing intermediates during peripheral insulin resistance. Possible examples are an increased demand for secretion due to
a rapid turnover of secretory granules, aberrant processing
resulting from altered activity of the prohormone convertases PC1/3 or PC2 or of their activators such as 7B2 (33, 443)
and SAAS (205).
There is immunological evidence for the presence of
proIAPP in amyloid deposits (384), even though the detected amount constitutes only a minute proportion of the
total amyloid mass. In an in vitro study with only synthetic
materials, proIAPP was less amyloidogenic in the presence
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It was noted early after the discovery of IAPP that ␤-cells in
islets containing amyloid had completely or partly lost their
IAPP immunoreactivity (311, 407). This change was found
with several different polyclonal antisera and also in islets in
cats with and without islet amyloid (165). The reduction is
not due to lost expression of the polypeptide gene, since the
presence of mRNA was demonstrated (380). Surprisingly, a
monoclonal antibody against IAPP reacted with equal
strength to ␤-cells in islets with and without amyloid deposits (220), suggesting an aberrant structure or binding of
IAPP in amyloid-contaning islets. On the other hand, in a
cat model of type 2 diabetes, animals with impaired glucose
tolerance but without diabetes displayed increased IAPP
immunoreactivity versus normal in ␤-cells, indicating that a
transient overproduction of the peptide may precede the
diabetic state (165, 219).
elevated levels of unprocessed proinsulin and of the des.-31,
32 processing intermediates of proinsulin are present (374).
Since proIAPP processing takes place at the same location,
an increase in proIAPP and partially processed proIAPP is
expected to occur early in development of type 2 diabetes as
well, and this has recently been partly verified (441). When
IAPP was purified from an insulinoma and from human and
feline islet amyloid, only full-length molecules were identified (64, 403– 405). However, immune electron microscopic (EM) studies with antibodies specific for proIAPP
have shown that the intracellular amyloid, in addition to
mature IAPP contains proIAPP. ProIAPP as well as its two
possible processing intermediates are in themselves highly
amyloidogenic (see below), and an intracellular abnormality leading to aggregation of one of them may be the initial
event in amyloid formation (139, 290, 291). Also, prolonged hyperglycemia per se may lead to a higher proportion of proIAPP and intermediates in islets (142).
WESTERMARK ET AL.
of artificial lipid membranes (185). We have studied the
significance of proIAPP processing for amyloid formation
by expressing preproIAPP in cell lines with different patterns of prohormone convertase expression: in beta-TC-6
cells that express PC2 and PC1/3, in AtT-20 and GH3 that
express PC1/3 and PC2, respectively, and in GH4C1 and
Cos-7 cells that lack convertase expression (291). Intracellular amyloid accumulated in AtT-20, GH4C1, and Cos-7
cells, lines with aberrant prohormone convertase processing. The number of transfected cells decreased more rapidly
over time in cells where amyloid developed, a sign of amyloid toxicity. In cells with a larger intracellular amyloid
mass, Congo red staining was shown to colocalize with the
apoptosis marker M30. If ER stress-induced apoptosis is
linked to the formation of toxic oligomers (see below), amyloid formation might for a limited time serve as rescue
pathway. Proteomic analysis of the secretory granule content has revealed the presence of multiple chaperone proteins (138). Their possible role in preventing IAPP aggregation still needs to be elucidated.
G. IAPP and ␤-Cell Death
During development of type 2 diabetes, peripheral insulin
resistance is compensated for by increased insulin production. When the exhausted ␤-cells fail to produce insulin in
sufficient amounts, type 2 diabetes develops (115, 170,
438). Islet amyloid is the cardinal finding in the islets of
patients with type 2 diabetes, but the reported percentage of
patients with amyloid has varied from almost 100% down
to 40% or less (21, 226, 392, 440).
The general characteristics of amyloid include the presence
of unbranched fibrils of an indefinite length and with a
diameter of 7–10 nm (63). The built-in monomers are assembled into a ␤-sheet structure, arranged perpendicularly
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to the fibril axis (see above). Amyloid formation is a nucleation-dependent process that can be divided into three different phases. The first is the lag phase, the rate-limiting step
during which nucleation of monomeric peptides occurs.
The duration of this period varies from some minutes to a
lifetime, depending on the protein and other variables such
as concentration and temperature. The second phase is the
elongation phase, in which amyloid fibrils are propagated,
and the third phase, at least in in vitro systems, is the plateau
phase when the fibrillation has reached steady state and the
fibrillar mass is constant. Amyloid formation is a self-driven
process that after initiation continues as long as the precursor is present at a sufficient concentration.
There is little morphological difference between amyloid
fibrils made up of each of the hitherto almost 30 described
amyloid proteins. Nevertheless, it is known that the morphology of the fibrils may vary, even within a specific biochemical amyloid form, including that derived from IAPP
(389). Regarding systemic amyloidosis, where large amounts, often kilograms, are deposited in different tissues, such as the
liver, kidney, or heart, it is obvious that the amyloid masses
themselves are sufficient to cause severe disease (244, 295).
The mature amyloid fibril is presumed to be relatively inert
and to have no significant cell toxicity. Rather, smaller oligomeric intermediates formed during fibrillogenesis are
thought to be cytotoxic. The amyloid fibril protein in Alzheimer’s diseases is A␤, which is a 40 – 42 amino acid fragment of the much larger A␤ protein precursor (A␤PP) (for
review, see Ref. 77). The whole field of toxicity in the pathogenesis of amyloid-associated diseases started with studies
by Yankner and co-workers (424, 425), in which they
showed that a COOH-terminal fragment of the A␤-precursor and A␤ are neurotoxic in vitro. These findings created a
severe controversy in Alzheimer’s research, since a number
of researchers were not able to reproduce the results (232).
FIGURE 7 A hypothesis proposing how islet amyloid formation occurs. The initial amyloid accumulation
occurs intracellularly and leads to extracellular deposits. A: the initial aggregation is intracellular and takes
place in membrane-encircled compartments, e.g., secretory granules. At this location at least some of the
amyloid is made up by proIAPP. B: deposited amyloid perforates membrane structures and fuses into larger
deposits. C: in time the amyloid masses grow and replace the cytoplasmic compartment and induce apoptosis.
D: amyloid that escapes degradation will remain extracellularly. E: at this location, the extracellular amyloid
functions as a seed for propagation of deposits, which are now made up of mature IAPP, secreted from the
surrounding ␤-cells. [Modified from Paulsson et al. (290), with kind permission from Springer Science ⫹
Business Media.]
The issue of protein toxicity entered the diabetes field in
1994, again through a study by the Yankner group (211), in
which they showed that fibrils of human IAPP are toxic to
adult human and rat islet cells in vitro. They also reported
evidence that the toxic mechanism leads to apoptosis. These
initial studies indicated that amyloid fibrils constitute the
toxic forms of both A␤ and IAPP (212). Subsequent reports
have underlined that it is small, oligomeric IAPP aggregates
and not fibrils that constitute the toxic species (159). The
role of amyloid protein toxicity is presently an important
open question in the research of the pathogenesis of Alzheimer’s disease, and is also a central subject in the discussions
concerning the cause of the ␤-cell lesion in type 2 diabetes.
In preparations of oligomers produced in vitro, a variety of
prefibrillar structures can be detected, some of which are
annular in shape. They resemble the membrane-inserted
structures, but they lack the ability to permeabilize membranes (181). Instead, smaller prefibrillar oligomers seem to
be inserted into cell membranes. At these locations they
form annular structures that allow ions to leak. Oligomerspecific antibodies that are said to recognize common structures independently of the amyloid protein have been produced (180). This finding strengthens the view that amyloid
fibril formation is a specific process involving mechanisms
that are independent of the actual nature of the amyloid
protein (86, 122). However, weaknesses in all conclusions
drawn so far are that studies on oligomers are mainly performed in vitro and that the existence of toxic oligomers in
FIGURE 8 In response to an unknown signal, a natively folded protein may start to unfold and misfold. This
is a reversible event and occurs most likely intracellularly. If misfolding continues, it will initiate a large number
of processes, including ER stress, UPR, oxidative stress, and ROS production. If not dealt with properly, toxic
oligomers can develop. These can be inserted into membranes and at this location form ion-leaking pores. An
alternative toxic pathway is association of misfolded monomers or oligomers with membrane structures. A
continuation of fibril growth can lead to the frequently seen invaginations and disruptions of cell membranes.
Both intra- and extracellular aggregation can cause these latter cell toxic processes.
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A major problem in this area is that the oligomers are illdefined. These aggregation intermediates, often referred to
as prefibrillar oligomers, oligomers, protofibrils, intermediate-sized toxic amyloid particles, or amyloid oligomers
(120, 181), have been studied extensively in vitro. It was
suggested at an early date that they are inserted into the cell
membrane, wherein they form functioning ion channel-like
structures (10, 200, 246, 299). This pore forming capacity
has been proposed to be a universal cytotoxic mechanism
for all amyloid proteins, and analyses of the composition of
pores recovered from artificial lipid bilayers have revealed
oligomeric complexes of trimers up to octamers, depending
on the amyloid protein. For IAPP the major inserted complexes were of the trimeric and hexameric type (305). Suggested mechanisms by which IAPP may permeabilize membranes are either through formation of toroidal (doughnutlike) pores or by nonspecific membrane disruption due to
excessive negative curvature strain (337) (FIGURE 8).
WESTERMARK ET AL.
vivo has to be proven more than just indirectly. However,
evidence of soluble oligomers has been obtained from extracts of the brain of Alzheimer-model mice (208) and recently also from human brain tissue (355). Some evidence
for formation of toxic human IAPP oligomers in vivo has
also been obtained from studies in transgenic mice (209)
and recently in human pancreatic tissue (128). However,
the role of IAPP oligomers is still somewhat controversial,
and it is too early to rule out the importance of mature IAPP
amyloid fibrils in the pathogenesis of the ␤-cell failure in
type 2 diabetes (448).
Cholesterol and other lipids have been suggested to be involved in human IAPP amyloidogenesis and the resulting
cell death (162). Exogenic human IAPP aggregated into
cytotoxic fibrils in cholesterol- and ganglioside-rich rafts in
plasma membranes (369). On the other hand, cholesterol
inhibited human IAPP aggregation on synthetic membranes
(52). Results of one study indicated that human IAPP may
induce apoptosis by activation of acid sphingomyelinase,
which would lead to production of ceramide (439).
An interesting recent finding is that aggregated IAPP can
activate the inflammasome to produce processed interleukin-1␤, which may cause ␤-cell death (237). IAPP also induced release of interleukin-1␣ that might be of importance
for inflammation in pancreatic islets (237).
H. Can Amyloid Be Harmless
or Even Protective?
As mentioned above, the mature fibril in all forms of amyloid has been considered to be nontoxic, and therefore small
amyloid deposits such as those often seen widely spread in
islets in type 2 diabetes have been thought to have no significant impact on islet function. The correctness of this
assumption should certainly be questioned, since the pres-
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The pancreatic islet is a highly vascularized tissue with ␤-,
␣-, ␧-, ␦-, and PP-cells, and at least the ␤-cells make up an
electrically synchronized unit (126, 262), with pulsatory
release of insulin (129, 197, 341). The ␤-cell coupling seems
to be essential for sustaining optimal insulin gene expression, insulin synthesis (20), and proper oscillatory behavior
(9, 353). Gap junction channels made up of connexin-36
(327) form the cell-cell connection of ␤-cells, and in connexin-36-deficient mice, the synchronized glucose-induced
calcium and insulin oscillations are altered (306). Incubation of human islets with 40 ␮M human IAPP resulted in a
90% reduction of insulin secretion stimulated with 16 mM
glucose, and in an increase in islet diameter, a morphological change that was interpreted as resulting from disruption of cell-cell couplings and not from hypertrophy of individual ␤-cells (309). The synchronization of secretion was
found to be markedly disordered from islets incubated with
human IAPP and stimulated with 16 mM glucose. The question of whether IAPP oligomers exist in the islets of Langerhans in vivo remains to be answered, and if they do, for
how long will they remain as cell toxic species? It has been
suggested that formation of amyloid fibrils is a protective
mechanism of taking care of dangerous protein aggregates
and transforming them into inert deposits. It might be appropriate to ask whether amyloid formation is initially a
rescue pathway that acts to prolong cell survival (86).
X. ENDOPLASMIC RETICULUM STRESS
AND UNFOLDED PROTEIN RESPONSE
A common term for the dysfunction of ␤-cells in type 2
diabetes is “pancreatic ␤-cell exhaustion,” which in reality
may be equivalent to ␤-cell stress (11). For reviews on the
importance of ER stress in diabetes, reference should be
made to Eizirik et al. (95) and Fonseca et al. (109).
One important component of type 2 diabetes is peripheral
insulin resistance that for some time may be compensated
for by an enhanced insulin biosynthesis. The increased demand on the secretory machinery in the ␤-cells results in the
development of ER stress. An increase in insulin biosynthesis in the stressed ␤-cell is paralleled by an increase in synthesis of IAPP (257). Proteins destined for exocytosis are
transported through the ER and trans-Golgi complex and
stored in secretory granules prior to secretion. ER is a tubular and saclike system where proteins fold into their native structure and the posttranslational modifications are
In a proposed model on IAPP cytotoxicity, based on findings when IAPP was absorbed onto or inserted into a lipid
membrane, the 19 NH2-terminal amino acid residues are
inserted in the membrane (100, 184). Insertion in this way
leaves the amyloidogenic segment of residues 20 –29 free to
aggregate, and fibril growth will force the membrane to
rupture (100, 101). An important difference from other
models is that it is monomeric IAPP that initially interacts
with the membrane rather than oligomers or fibrils. Likewise, Soong et al. (342) have suggested that human IAPP
monomers associate with the cell membrane. In addition,
multiple factors such as protein concentration, other proteins including chaperones, temperature, and pH play a
crucial role for aggregation of a fibrillogenic protein into
amyloid (42). It is also possible that enrichment of amyloidogenic peptides in the vicinity of the membrane can
create microenvironments where the peptide concentration
is high enough to induce aggregation.
ence of amyloid, even in limited amounts, affects the cytoarchitecture of the islets, and insulin secretion is dependent
on cell-to-cell contacts (416). When human islets were
transplanted to a site under the kidney capsule of nude
mice, amyloid developed within 2 wk in 75% of the implants (397). At high resolution, thin streaks of amyloid
could be seen to protrude between ␤-cells, which then became separated.
Expression and activation of XBP-1 increases ER capacity
by upregulation of UPR genes such as the chaperone Bip
(203) and protein disulfide isomerase (PDI) and by expansion of rough ER (344). PDI is an enzyme that in addition to
catalyzing the native formation of disulfide bonds in peptides entering ER, also assists in folding of nascent peptides
and is classified as a foldase (36, 340). Activation of PERK
in response to ER stress inhibits overall new protein synthesis (54, 133) in favor of translation of selected mRNAs, e.g.,
chaperones that are important for persistent proper protein
folding.
Persistent ER stress activates apoptosis and IRE1 (372), PERK
(132), and ATF6 (431), all of which activate transcription of
CHOP (C/EBP homologous protein/GADD153). Under normal conditions, CHOP is present at very low concentrations
in the cytoplasm, but upon activation, synthesis increases
and CHOP translocates to the cell nucleus and induces cell
cycle arrest and DNA fragmentation (17, 94). IRE1 signaling can also activate cell death through activation of the
c-jun NH2-terminal kinase (JNK) pathway (364). Procaspase-12 in mice, equivalent to caspase-4 in humans
(133), is present in ER, and its activation during ER stress is
linked to an increase in apoptosis (263). Treatment of human cells with caspase-4 siRNA lowers ER stress-induced
apoptosis (133). The mechanism of the signaling cascade
downstream of caspase-12 is not fully resolved but might
relate to caspase-9-linked apoptosis. ER stress has been reported to occur in ␤-cells in patients with type 2 diabetes
and to result in apoptosis (201). Taken together and with
the knowledge that IAPP in vitro is one of the most aggregation-prone amyloid peptides and that islet amyloid is
present in pancreata of a great majority of patients with
type 2 diabetes, it is obvious that induction of IAPP aggregation as a cause of ER stress and of apoptosis, as proposed
by Peter Butler’s team, is highly relevant. This research
group showed that overexpression of human IAPP in the rat
triggers apoptosis and reduces the ␤-cell mass (38, 239). A
sixfold increase in CHOP-positive cell nuclei was detected
in human pancreatic sections of type 2 diabetic subjects, but
was not present in nonobese or obese nondiabetic subjects
(145). An increased production of the ER-stress markers
HSPA5, DDIT3, DNAJC3, and BCL2-associated X protein
was detected in human pancreas recovered from diabetic
subjects (201). However, in this immunological study,
CHOP reactivity was restricted to the cytosol without
translocation to the cell nucleus where it could mediate
ER-stress related apoptosis (238).
The ER density volume (calculated from the relative area
taken up by ER in electron micrographs) and apoptosis rate
were increased in ␤-cells from patients with type 2 diabetes
compared with those in islets from nondiabetic individuals
(227). Moreover, Bip and XBP-1 expression was upregulated in islets from type 2 diabetic individuals but not in
islets from nondiabetic subjects after culture in 11.1 mM
glucose for 24 h. This difference shows that islets from
patients with type 2 diabetes might be more vulnerable to
ER stress (227).
Consensus regarding the association between human IAPP
expression and induction of ER stress has not yet been
reached. Hull et al. (147), for instance, failed to detect ERstress induction in human islets and mouse islets expressing
human IAPP after culture at high and low glucose concentrations (147). The expression of Bip, ATF4, and CHOP
and splicing of XBP-1 mRNA were analyzed in islets isolated from human IAPP transgenic mice. Islet amyloid de-
809
started. There is a rigorous quality control system to ensure
that only correctly folded proteins are transported to the
Golgi compartment. A large variety of physiological and
pathological factors can perturb ER homeostasis and trigger ER stress as defined by the UPR. An increase in protein
synthesis (15, 131, 321) or obstruction of the ER-Golgi
transport (303) can lead to an accumulation of unfolded
proteins and trigger UPR. The UPR includes upregulation
of ER-located chaperones to assist folding of aggregationprone proteins; a selective inhibition of overall protein synthesis to reduce the ER work load, while selectively favoring
synthesis of proteins that augment the UPR; and transport
of misfolded proteins to the ubiquitin-proteasome system
(UPS) for degradation; and if these measures fail to reestablish homeostasis, induction of apoptosis (73, 228, 283,
323). The different pathways are regulated by the three
sensors ATF6 (activating transcription factor 6 alpha),
IRE1 (inositol requiring 1), and PERK (PKR like ER kinase). These pathways seem to function in concert (423,
430). In response to ER stress, the chaperone Bip/GRP78, a
negative regulator of ATF6, detaches from ATF6 inserted in
the ER-membrane, which leads to a translocation of ATF6
from ER to Golgi complexes (50). The cytosolic part of
ATF6 is proteolytically cleaved off from the membrane and
transferred to the cell nucleus, and activates transcription of
genes encoding for chaperones and folding enzymes and
proteins, active in the ER-associated degradation (ERAD).
Nuclear ATF6 initiates induction of the X-box binding protein (XBP-1). This second transcription factor becomes activated after mRNA splicing by ER-stress activated IRE1
(41, 141). XBP-1 enhances transcription of ER chaperone
genes, and the spliced form of XBP-1 can autoregulate its
transcription in the presence of activated IRE1 (203). Incubation of human pancreatic islets with freshly solubilized
human IAPP increased expression of hsp90 and splicing of
XBP-1. A reduction in the proteasome activity had occurred
after 1 h and contributed to accumulation of ubiquitinated
proteins in the cytosol, followed by a dysregulation of the
ubiquitin-proteasome pathway, thus contributing to apoptosis (45) (FIGURE 9). Ubiquitination of proteins marks
them for degradation by the proteasome, but they must be
deubiquitinated prior to insertion into the proteasome
(409). The polyubiquitine is removed by the ubiquitin
COOH-terminal hydrolases (198).
WESTERMARK ET AL.
veloped and was associated with a reduced ␤-cell area in a
glucose- and time-dependent manner. However, amyloid
formation was not associated with significant increases in
expression of ER stress markers (147). Furthermore, ␤-cell
apoptosis induced by IAPP amyloid was in short term independent of oxidative stress and antioxidant treatment inhibited rise in ROS, but did not prevent accumulation of
amyloid (446) (FIGURE 9).
810
XI. AUTOPHAGY
Autophagy is a well-preserved catabolic process that is
active in degradation and recycling of misfolded proteins
and excess of, or defective, organelles. The targeted material is encircled by a double membrane structure
(phagophore), which together with the engulfed material
is referred to as an autophagosome. The autophagosome
FIGURE 9 Hypothetical ways by which IAPP aggregates may develop and be toxic. Proteins destined for
secretion are transported through ER and Golgi compartments to undergo folding and posttranslational
modification. Protein misfolding in the ER compartment leads to ER stress that triggers the unfolding
protein response (UPR). UPR includes the upregulation of ER-located chaperones to assist refolding of
misfolded proteins and a selective inhibition of protein synthesis to reduce ER work load in favor of protein
synthesis that augments UPR. A: proteins that remain misfolded are transported over the ER membrane
to the ubiquitin-proteasome system (UPS) for degradation. B: cytotoxic oligomers develop in ER and Golgi
compartments after overexpression of proIAPP or IAPP in experimental models and in ␤-cells from
subjects with type 2 diabetes. These oligomers enter the cytosol, and at this new location they can
perforate membranes of other organelles, e.g., mitochondria, and cause oxidative stress and reactive
oxygen species (ROS) production. ROS damaged proteins might have a decreased activity that has an
impact in many vital cell pathways. Since proIAPP is processed to IAPP in the secretory granules, peptides
that enter the cytosol from ER and Golgi are most likely proIAPP. C: amyloid-like fibrillar structures are
frequently present in the halo-region of secretory granules in human IAPP transgenic mice. These fibrils
are to some extent recognized by proIAPP-specific antibodies. The amount of fibrillar material differs, but
in some cells a fraction of the secretory granules is replaced by fibrillar material and fusion of granules may
occur. In granules with a more advanced amyloid content, the membranes may disrupt and fibrillar
material can occupy almost the entire cytosol. D: aggregated proteins cannot be degraded by the
proteosome pathway. Instead, aggregates are degraded by the catabolic process autophagy. Aggrephagy
is a special form of autophagy used for degradation of ubiquitinated protein aggregates. Autophagosomes
will fuse with lysosomes, forming an autophagolysosomes. When the maturation of autophagolysosomes
is hampered, this leads to an increased accumulation of material in autophagic vacuoles, which disturbs
intracellular transport. Disturbance in any of the above pathways might have a dramatic impact on the
intracellular milieu and induce apoptosis. In the cartoon, proIAPP molecules and aggregates are red, IAPP
molecules and aggregates are green, ubiquitine is blue, ROS are maroon stars, lysosomes or lysosomal
material are yellow, and autophagosomes are purple.
Autophagy can be induced in response to ER stress. The ER
stress stimulates both phagophore and autophagosome formation. Atg1 kinase activity, which reflects initiation of
autophagy, is upregulated during ER stress-induced autophagy (427– 429).
Autophagy is connected to amyloid formation in situations
where the maturation of autophagolysosomes is hampered.
This leads to an increased accumulation of material in autophagic vacuoles, which is a sign of disturbance in the
lysosomal system (271). Autophagy-related gene becn1 (Beclin 1) is the mammalian ortholog of yeast Atg6. Beclin 1 is
localized in the trans-Golgi network and participates in the
formation of the autophagosome after forming a complex
with the class III phosphatidylinositol 3-kinase human vacuolar protein sorting factor protein (hVps34). The proautophagic interaction between hVps34 and Beclin 1 is inhibited by Beclin 1 interaction with antiapoptotic Bcl-2 localized in the ER (224). Binding between Beclin 1 and Bcl-2
requires binding of the redox-regulated NAF-1 (nutrientdeprivation autophagy factor-1) to Bcl-2 (47). Binding decreases under starving condition but may increase, e.g., under growth in the presence of nutrients. Therefore, binding
of Beclin 1 to Bcl-2 can either promote or prevent macroautophagy (289). Beclin 1 expression is decreased in degenerating neurons in Alzheimer’s disease, and Beclin 1 heterozygous deficiency in mice causes Alzheimer’s-like pathology
(297) (FIGURE 9). Beclin 1 deficiency might interfere with
the formation of autophagosomes and may well lead to an
increase in intracellular accumulation of aggregated proteins.
Aggrephagy is a special form of macroautophagy used for
degradation of protein aggregates present in the cytosol
(365, 376). The autophagy receptors p62 [also known as
sequestosome1 (SQSTM1)] and NBR1 (neighbor of BRCA
gene 1) bind to the ubiquitine present on protein aggregates
destined for degradation and to LC3-II present on the autophagosome membrane, and thereby direct and promote
degradation of the aggregate (187, 286, 376).
At present, the knowledge of the role (if any) of autophagy
in the formation of IAPP amyloid and the development of
the ␤-cell apoptosis that occurs in type 2 diabetes is limited,
but Masini et al. (235) detected accumulation of autophagic
vacuoles and autophagosomes in islets isolated from diabetic organ donors compared with nondiabetic donors
(235). Moreover, they found that the number of ␤-cells was
reduced. Quantitative RT-PCR analysis revealed unchanged expression of Beclin 1 and Atg1, while transcription of LAMP2 and cathepsins B and D was reduced. This
indicates a reduction of lysosomal activity (235).
It is reasonable to believe that a variety of mechanisms are
involved in amyloid-induced apoptosis. ER-stress, UPR,
and ERAD are activated by protein aggregation in the ER
compartment. Prefibrillar amyloid aggregates can disrupt
mitochondrial membrane (128, 287) and cause metabolic
dysfunction with induction of oxidative stress and ROS
production, consequently damaging proteins (320). Oxidative stress stimulates the ubiquitin-activating enzymes leading to a selective removal of damaged proteins (329). If the
ubiquitin pool is fixed, a change in UCH L-1 activity might
deplete ubiquitin available for ubiquitination, or the proteosome may be obstructed by polyubiquitinated proteins
(46). A reduction of UCH-L1 protein levels has been detected in islets from type 2 diabetic individuals (67). Atg4 is
redox-regulated, and low levels of H2O2 can cause a decrease in Atg4 deconjugating capacity of LC3-II, with an
increased accumulation of autophagosomes. An intracellular overload of autophagosomes induces type II cell death
(37). More advanced ROS production generates general
protein damage with a decrease in protein function that
affects different cellular pathways. Protein aggregates cannot be degraded by the proteosome pathway. Instead, intracellular amyloid can be ubiquitinated and degraded by
aggrephagy. Some general mechanisms have been summarized in FIGURE 9.
XII. AMYLOID FORMATION IN
TRANSPLANTED PANCREATIC ISLETS
Almost 15 years ago we conducted a study with the ultimate
aim of finding an appropriate experimental in vivo model to
investigate the pathophysiological relevance of islet amyloid formation for islet function. For that purpose we
grafted isolated human pancreatic islets from nondiabetic
subjects to a site beneath the renal capsule of nude mice
(397). Human islets survive for a long time at an ectopic site
as evidenced by studies regarding, for instance, susceptibility of human ␤-cells to agents known to be toxic to rodent
811
fuses with a lysosome and forms an autolysosome, and
degradation begins (14, 90, 104). This type of autophagy
is named macroautophagy (78). A panel of autophagyrelated genes (Atgs) participate in the autophagy process.
Atg1 is involved in the early steps of the formation of the
phagophore (356). Microtubule-associated protein 1
light chain 3 (LC3 or Atg8) and Atg12-Atg5 participate
in the formation of the autophagosome (281, 348). LC3
is cleaved at the COOH terminus by the protease Atg4
(186) to form cytosolic LC3-I. Atg7 and Atg3 convert it
into LC3-II by COOH-terminal conjugation of phosphatidylethanolamine (PE) (153, 350), and LC3-II is often used as a biological marker for autophagy induction
(249). Atg4 cleavage of LC3 is the first step for its conversion into LC3-II, but Atg4 is also responsible for the
deconjugation of LC3-II that releases LC3-I from the
mature autophagosome membrane (250). This deconjugation prevents fusion of the autophagosome with the
lysosome and further degradation, but it allows LC3-I to
be recycled.
WESTERMARK ET AL.
␤-cells (97). In that first study, we found that antisera
against insulin and IAPP stained the same cells in islet
grafts. More challenging was our finding of IAPP-positive
amyloid deposits in two-thirds of the islet grafts. This section describes how these findings have been extended to
include experiments with islets isolated from mice transgenic for human IAPP and to take into account evidence to
suggest that amyloid formation is indeed a likely candidate
as a cause of the long-term failures of clinically grafted
human islets.
A. Experimental Islet Transplantation
Comparisons of adjacent sections of human islet grafts that
had resided in nude mice for 2 wk and were then subsequently stained for insulin and for IAPP indicated that the
antisera stained the same cells (397). EM investigations
showed explicitly that IAPP immunoreactivity normally
was confined to the secretory granules of the ␤-cells, while
␣- and ␦-cells were negative. Our finding of a lower percentage of IAPP-positive cells in the grafts of hyperglycemic
mice was interpreted as indicating that the storage of the
substance was decreased after hyperglycemia. Interestingly,
we found amyloid deposits in human islet transplants by
means of Congo red stainings in six of eight normoglycemic
and two of four hyperglycemic recipients. The deposits
seemed to be extracellular, but small and very faintly
812
Our ultrastructural findings have recently been confirmed
in a study published by Davalli et al. (72). They grafted
human islets to a site under the renal capsule of streptozotocin diabetic nude mice. A great majority of them remained
hyperglycemic, and only recipients of islets from one donor
(“fully effective prep”) became normoglycemic. While the
number and ultrastructural appearance of the ␣-cells remained fairly intact, the ␤-cells decreased in number and
were often only sparsely granulated. The same group also
demonstrated densely packed IAPP-positive fibrillar deposits in the reticulum cisternae and in the extracellular spaces
of the ␤-cells (108). Exact information on how long the
grafts had resided under the renal capsule was not given in
their paper.
Essentially all clinical islet transplantation has so far been
carried out by intraportal infusion of the islet graft to the
diabetic patient. We were therefore interested in investigating the possible deposition of amyloid in intraportally
grafted islets. Nude mice were used as recipients of human
islets, and indeed, amyloid exhibiting affinity for Congo red
was found in a great majority of the islets of intraportally
grafted animals (387). We also found that intrasplenically
grafted islets contained amyloid with the same appearance
as in the intraportally implanted human islets. The same
study also showed that islets that had resided as long as 6
mo under the renal capsule most often contained fairly large
amyloid deposits, all of which were located extracellularly.
Since human islets are only irregularly offered for experimental use and their quality and biological origin vary considerably, it would be of great help if the islet availability
could be more predictable and quality assured. Obviously
transgenic mice overexpressing human IAPP would be of
benefit in this context. Most of the mouse strains expressing
human IAPP do not form islet amyloid in vivo unless hyperglycemia or hyperlipidemia is imposed on the islets (76,
367, 378). Normally, many months of exposure are necessary for amyloid to develop in these animals. We compared
the formation of amyloid in human and hIAPP transgenic
mouse islets grafted into nude mice, with the same mouse
serving as recipient of both human and mouse islets (386).
Again extensive deposition of amyloid occurred after only
Ever since the early 1970s, experimental islet transplantation has been successfully carried out with inbred mouse
and rat strains, using collagenase isolated islets as grafts.
The islets have been either freshly isolated or cultured for a
number of days. Although intraportal injections were
mostly used as the infusion route of choice in initial studies
(182), the subcapsular site of the kidneys has since become
more frequently preferred, mainly because of the fairly simple surgical procedure but also because of the possibility of
easily recovering the graft for histological and biochemical
investigations (96, 242, 359) or of performing perfusion
studies of the graft-bearing kidney (193). In the context of
islet xenografting, nude mice have been frequently used as
recipients of different preparations of endocrine pancreatic
material, such as, for instance, human fetal pancreas (317)
and fetal (194) or adult porcine islets (99). When human
islets, isolated by fairly reproducible techniques, became
available, such recipients, normoglycemic or made diabetic
by injections of alloxan or streptozotocin, were used in
studies of effects of hyperglycemia on human ␤-cell function (96, 161), replication (359, 361), or susceptibility to
␤-cell toxic agents (97, 358, 360). Keeping in mind the
difference in the IAPP amino acid sequence that prevents
amyloid formation in rodent islets, the availability of human islet specimens in an in vivo setting of this kind has
paved the way for experimental studies of the presence of
fibrillogenic IAPP and accompanying amyloid formation in
human islets.
stained deposits were obviously also present in the cytoplasm. There was, however, no clear difference in occurrence of amyloid between nondiabetic and alloxan-diabetic
recipients. As in the light microscopical study, our ultrastructural examinations showed accumulation of amyloid
material, strongly labeled with antisera to IAPP, in many
grafts. Large amounts of amyloid fibrils were easily recognized, but sometimes the amyloid material also had a granular appearance. The amyloidogenic process was obviously
quite rapid and took place in the islet grafts, since no amyloid was found in sections of the donor pancreata collected
before they were processed for islet isolation.
It is quite obvious from the data gathered so far on amyloid
formation in transplanted islets from nondiabetic subjects
that such a process never develops to the degree of amyloid
deposition seen in the islets of type 2 diabetes patients. The
reasons for this are still unknown, but clearly the present
experimental model should offer unique opportunities for
such studies. While awaiting further mechanistic studies, it
is tempting to speculate that the first amyloid is formed
intracellularly and that amyloid at a later stage acts as a
nidus for further, extracellular deposition. One circumstance that might explain the rapid deposition of amyloid in
the grafted islets is their fairly low vascular density compared with the endogenous islets in the pancreas (44). Such
a relative lack of blood vessels, counteracting an effective
export of secretory products from the islets, might facilitate
the accumulation of IAPP and, as a result, formation of
amyloid.
To test this hypothesis, we looked for the presence of amyloid deposits in microencapsulated islets. Such islets survive
for many weeks despite their existence as a totally nonvascularized islet graft (31). For that purpose we encapsulated
both human islets and hIAPP transgenic mouse islets in a
high-guluronic alginate solution (30). These capsules were
subsequently transplanted into the renal subcapsular space
of normoglycemic nude mice and retrieved 4 wk later (S.
Bohman, A. Andersson, and G.T. Westermark, unpublished data).
The preliminary results of that study suggest that considerable amounts of amyloid had been formed in the ␤-cells of
the encapsulated islets, probably much more than in nonencapsulated islets. This may be taken to indicate that a
distorted or at least malfunctioning blood perfusion of the
islets enhances amyloid formation. To analyze this further,
the encapsulation technology might offer unique opportunities for detailed molecular studies of the amyloid formation process in pancreatic islets.
B. Clinical Islet Transplantation
Trials with clinical islet transplantation were carried out in
the 1980s and 1990s, but the results were mainly disappointing (349). Thus overall only ⬃10% of islet recipients
achieved normoglycemia without insulin therapy. Almost
10 years ago the Edmonton group spread more enthusiasm
to this field of research when reporting that a handful of
diabetes patients had become normoglycemic and free from
insulin therapy after two or three intraportal implantations
of human islets (330). Most of these patients remained off
insulin therapy for at least 1 year when given transplants
with a higher number of islets and immunosuppression
lacking steroids. A detailed follow-up of subjects with type
1 diabetes having undergone this type of treatment showed
that ⬃80% of the patients had C-peptide production after 5
years, but that only ⬃10% maintained insulin independence (313). It was concluded that there was a progressive
loss of islet function in most subjects, all of whom had
become insulin-independent initially. We suggested that aggregation of IAPP may be an important cause of the loss of
␤-cell function in transplanted islets (395). Reports on the
pathology of clinically grafted islets are very sparse, but last
year two publications were added to the report by Davalli et
al. almost 10 years ago (71). Besides our own report specifically focusing on the presence of amyloid in the grafted
islets (385), there was one from the Boston group (338)
challenging immunological reasons for the loss of islet function. In our study we demonstrated widespread amyloid
deposition in the islets implanted in a patient with type 1
diabetes for more than 35 years. He died of myocardial
infarction 5 years after the first of three intraportal islet
infusions. In almost every second islet of a total of 89 islets
found in the liver tissue blocks, amyloid deposits were identified (FIGURE 10). Our light microscopic findings were corroborated by immunoelectron microscopic investigations.
Despite considerable technical difficulties, we were able to
demonstrate amyloid fibrils in the grafted ␤-cells that were
positive for antibodies against IAPP. In the Boston study, no
attempts were made to identify amyloid in the light microscopic study. Electron microscopy was performed on islets
derived from paraffin-embedded and Formalin-fixed tissue.
No amyloid fibrils were identified in such specimens. There
is a possibility that the amount of tissue scrutinized was too
small, keeping in mind our observation that only every
other islet contained amyloid. Evidently, the amount of tissue available for studies has been limited, since no light
microscopic examinations were carried out in attempts to
identify amyloid deposits. In the Italian study (71) amyloid
deposits were not looked for.
Long-term results of clinical islet transplantation are fairly
discouraging, although the reports on this matter are con-
813
14 days in the human islets, whereas amyloid deposition in
the transgenic mouse islets was sparse and only detected by
electron microscopy. It is worthy of note that the amyloid
deposition in islets of transgenic mice expressing hIAPP and
in human islets differed considerably. In the human islets
amyloid was mainly formed intracellularly, whilst in islets
from transgenic mice the amyloid was exclusively deposited
extracellularly. These animals carried eight copies of the
human IAPP gene but also expressed murine IAPP. Their
plasma IAPP levels were elevated fivefold (110). Later studies have shown, however, that in hIAPP transgenic animals
not expressing the mouse molecule, the first amyloid occurs
inside the ␤-cells (290). Furthermore, recent studies of human IAPP transgenic islets or control islets grafted into
streptozotocin-diabetic mice showed that hyperglycemia recurred only in mice that had received transgenic islets. Amyloid deposition occurred prior to the recurrence of hyperglycemia, and was accompanied by increased rates of ␤-cell
apoptosis and decreased ␤-cell replication (362). The accumulation of amyloid correlated with the loss of ␤-cells.
WESTERMARK ET AL.
filicting (183, 245, 366). There is strong evidence, however,
to suggest that there is a progressive loss of the grafted
␤-cells that is not compensated for by regeneration of new
␤-cells. Moreover, it is obvious from the three published
autopsy studies that a non-immune-mediated ␤-cell loss is
the cause of graft functional deterioration. But knowledge
on the nature of that process is meager, and the importance
of performing autopsies under the guidance of pathologists
experienced in different aspects of islet pathology, including
islet amyloidosis, cannot be sufficiently strongly underlined. By such means further insights into the nature of the
destructive process(es) should be gained. Taken together,
our combined experimental and clinical data and the recent
confirming publications (72, 362) make it very plausible to
suppose that amyloid formation in the grafted human islets
is a cause of their long-term failure. This idea was recently
supported by the finding that porcine islet grafts, which did
814
not develop amyloid, had much better long-term viability
than human islet grafts (300).
XIII. FUTURE RESEARCH
It is important to understand what aggregation states of
IAPP are devastating and how such aggregates exert their
toxicity. Almost all studies of IAPP fibrillogenesis and of the
toxic effects of IAPP oligomers have been performed in
vitro. There is an obvious lack of in vivo studies in animal
models and in humans (448). The latter are difficult to carry
out, but it should be possible to analyze different forms of
human IAPP aggregates, extracted from pancreatic specimens, when such are available, and very recently Gurlo et
al. (128) reported evidence for toxic IAPP oligomers in the
ER of human ␤-cells. Given this localization, these oligom-
FIGURE 10 Amyloid deposits in transplanted islets in a patient with type 1 diabetes. A and B show an islet with heavy amyloid
deposits, stained with Congo red and immunolabeled for insulin. Two insulin-containing
cells are present after immunolabeling. The
amyloid exhibits typical green birefringence in
polarized light and is pointed out with white
arrows. C and D display islets that are immunolabeled for glucagon (green) or C-peptide
(green), respectively, and then labeled for
amyloid with Congo red. Both islets show
widely spread amyloid deposits. In E there is
an islet with pronounced amyloid deposits,
immunolabeled for IAPP (green). F is an electron micrograph showing a small intracellular
amyloid deposit immunolabeled with antibodies against IAPP and visualized with gold particles. [From Westermark et al. (385). Copyright Massachusetts Medical Society.]
ers most likely consisted of proIAPP molecules. Additionally, methods to visualize IAPP amyloid deposits in situ in
living experimental animals and finally in humans may become available, and positron emission tomography is of
particular interest in this context. It has already been successfully used for the demonstration of cerebral amyloid in
Alzheimer’s disease (189).
No conflicts of interest, financial or otherwise, are declared
by the authors.
REFERENCES
1. Abedini A, Meng F, Raleigh DP. A single-point mutation converts the highly amyloidogenic human islet amyloid polypeptide into a potent fibrillization inhibitor. J Am Chem
Soc 129: 11300 –11301, 2007.
2. Abedini A, Raleigh DP. Destabilization of human IAPP amyloid fibrils by proline mutations outside of the putative amyloidogenic domain: is there a critical amyloidogenic
domain in human IAPP. J Mol Biol 355: 274 –281, 2006.
3. Abedini A, Raleigh DP. A role for helical intermediates in amyloid formation by natively
unfolded polypeptides? Phys Biol 6: 015005, 2009.
4. Abedini A, Singh G, Raleigh DP. Recovery and purification of highly aggregation-prone
disulfide-containing peptides: application to islet amyloid polypeptide. Anal Biochem
351: 181–186, 2006.
5. Ahrén B, Oosterwijk C, Lips CJ, Höppener JW. Transgenic overexpression of human
islet amyloid polypeptide inhibits insulin secretion and glucose elimination after gastric
glucose gavage in mice. Diabetologia 41: 1374 –1380, 1998.
XIV. CONCLUSION
6. Ahronheim JH. The nature of the hyaline material in the pancreatic islands in diabetes
mellitus. Am J Pathol 19: 873– 882, 1943.
Islet amyloid was a puzzling islet phenomenon for more
than 80 years until its polypeptide nature was unraveled in
1986 –1987. Since then, IAPP has been associated with a
double controversy. First, its importance in health and disease as a hormone has been vigorously discussed. Second,
the role of aggregated IAPP in the development of the ␤-cell
lesion in type 2 diabetes has not yet become generally accepted (60, 401). However, recent results from transplantation of human and transgenic animal islets firmly indicate
that IAPP fibrils or oligomers have a crucial role in the
progressive failure of ␤-cells in transplants and thereby also
indirectly support a similar mechanism in type 2 diabetes.
These results point to the possibility of development of new
treatments in type 2 diabetes (176) and the use of islets that
do not develop IAPP-amyloid, e.g., from the pig (300), in
clinical transplantation.
7. Aitken JF, Loomes KM, Scott DW, Reddy S, Phillips AR, Prijic G, Fernando C, Zhang
S, Broadhurst R, L’Huillier P, Cooper GJS. Tetracycline treatment retards the onset
and slows the progression of diabetes in human amylin/islet amyloid polypeptide
transgenic mice. Diabetes 59: 161–171, 2010.
8. Akesson B, Panagiotidis G, Westermark P, Lundquist I. Islet amyloid polypeptide
inhibits glucagon release and exerts a dual action on insulin release from isolated islets.
Regul Pept 111: 55– 60, 2003.
9. Andreu E, Soria B, Sanchez-Andres JV. Oscillation of gap junction electrical coupling in
the mouse pancreatic islets of Langerhans. J Physiol 498: 753–761, 1997.
10. Anguiano M, Nowak RJ, Lansbury PTJ. Protofibrillar islet amyloid polypeptide permeabilizes synthetic vesicles by a pore-like mechanism that may be relevant to type II
diabetes. Biochemistry 41: 11338 –11343, 2002.
11. Araki E, Oyadomari S, Mori M. Impact of endoplasmic reticulum stress pathway on
pancreatic ␤-cells and diabetes mellitus. Exp Biol Med 228: 1213–1217, 2003.
12. Arey JB. Nature of the hyaline changes in islands of Langerhans in diabetes mellitus.
Arch Pathol 36: 32–38, 1943.
13. Arnelo U, Permert J, Adrian TE, Larsson J, Westermark P, Reidelberger RD. Chronic
infusion of islet amyloid polypeptide causes anorexia in rats. Am J Physiol Regul Integr
Comp Physiol 271: R1654 –R1659, 1996.
ACKNOWLEDGMENTS
We thank Maud Marsden for kind linguistic revision.
Address for reprint requests and other correspondence:
G. T. Westermark, Dept. of Medical Cell Biology, Biomedical Center, Box 571, SE-751 23 Uppsala, Sweden (e-mail:
[email protected]).
14. Arstila AU, Trump BF. Studies on cellular autophagocytosis. The formation of autophagic vacuoles in the liver after glucagon administration. Am J Pathol 53: 687–733,
1968.
15. Atkin JD, Farg MA, Walker AK, McLean C, Tomas D, Horne MK. Endoplasmic reticulum stress and induction of the unfolded protein response in human sporadic amyotrophic lateral sclerosis. Neurobiol Dis 30: 400 – 407, 2008.
16. Bai JP, Hong HJ, Rothenberger DA, Wong WD, Buls JG. The presence of insulindegrading enzyme in human ileal and colonic mucosal cells. J Pharm Pharmacol 48:
1180 –1184, 1996.
GRANTS
Our own research, referred to in this review, was supported
by the Swedish Research Council, the European Framework 6 Program “EURAMY,” the Swedish Diabetes Association, the Swedish Juvenile Diabetes Fund, and the Family
Ernfors Fund.
17. Barone MV, Crozat A, Tabaee A, Philipson L, Ron D. CHOP (GADD153) and its
oncogenic variant, TLS-CHOP, have opposing effects on the induction of G1/S arrest.
Genes Dev 15: 453– 464, 1994.
18. Barth SW, Riediger T, Lutz TA, Rechkemmer G. Differential effects of amylin and
salmon calcitonin on neuropeptide gene expression in the lateral hypothalamic area
and the arcuate nucleus of the rat. Neurosci Lett 341: 131, 2003.
815
Inhibition of islet amyloid formation in vivo will become a
matter of considerable interest. Already a number of agents
have been suggested as having this inhibitory effect including small peptides (43, 176, 261, 352) and other small molecules (7, 40, 136). It will be most interesting to test such
substances in animal models of diabetes, e.g., in monkeys or
cats, characterized by their deposits of amyloid in the islets.
The use of different islet transplantation protocols will open
up hitherto unknown possibilities of conductiong such
studies. Hopefully, future research of this kind will finally
show whether IAPP aggregation is important for the loss of
␤-cell function ultimately leading to type 2 diabetes.
DISCLOSURES
WESTERMARK ET AL.
19. Barth SW, Riediger T, Lutz TA, Rechkemmer G. Peripheral amylin activates circumventricular organs expressing calcitonin receptor a/b subtypes and receptor-activity
modifying proteins in the rat. Brain Res 997: 97–102, 2004.
20. Bavamian S, Klee P, Britan A, Populaire C, Caille D, Cancela J, Charollais A, Meda P.
Islet-cell-to-cell communication as basis for normal insulin secretion. Diabetes Obes
Metab 9 Suppl 2: 118 –132, 2007.
21. Bell ET. Hyalinization of the islets of Langerhans in diabetes mellitus. Diabetes 1:
341–344, 1952.
22. Bell ET. Hyalinization of the islets of Langerhans in nondiabetic individuals. Am J Pathol
35: 801– 805, 1959.
23. Benditt EP, Eriksen N, Hermodson MA, Ericsson LH. The major proteins of human
and monkey amyloid substance: common properties including unusual N-terminal
amino acid sequences. FEBS Lett 19: 169 –173, 1971.
24. Bennett RG, Duckworth WC, Hamel FG. Degradation of amylin by insulin-degrading
enzyme. J Biol Chem 275: 36621–36625, 2000.
40. Cabaleiro-Lago C, Lynch I, Dawson KA, Linse S. Inhibition of IAPP and IAPP(20 –29)
fibrillation by polymeric nanoparticles. Langmuir 26: 3453–3461, 2010.
41. Calfon M, Zeng H, Urano F, Till JH, Hubbard SR, Harding HP, Clark SG, Ron D. IRE1
couples endoplasmic reticulum load to secretory capacity by processing the XBP-1
mRNA. Nature 415: 92–96, 2002.
42. Calloni G, Lendel C, Campioni S, Giannini S, Gliozzi A, Relini A, Vendruscolo M,
Dobson CM, Salvatella X, Chiti F. Structure and dynamics of a partially folded protein
are decoupled from its mechanism of aggregation. J Am Chem Soc 130: 13040 –13050,
2008.
43. Cao P, Meng F, Abedini A, Raleigh DP. The ability of rodent islet amyloid polypeptide
to inhibit amyloid formation by human islet amyloid polypeptide has important implications for the mechanism of amyloid formation and the design of inhibitors. Biochemistry 49: 872– 881, 2010.
44. Carlsson PO, Palm F, Mattsson G. Low revascularization of experimentally transplanted human pancreatic islets. J Clin Endocrinol Metab 87: 5418 –5423, 2002.
45. Casas S, Gomis R, Gribble FM, Altirriba J, Knuutila S, Novials A. Impairment of the
ubiquitin-proteasome pathway is a downstream endoplasmic reticulum stress response induced by extracellular human islet amyloid polypeptide and contributes to
pancreatic beta-cell apoptosis. Diabetes 56: 2284 –2294, 2007.
26. Betsholtz C, Christmanson L, Engström U, Rorsman F, Jordan K, O’Brien TD, Murtaugh M, Johnson KH, Westermark P. Structure of cat islet amyloid polypeptide and
identification of amino acid residues of potential significance for islet amyloid formation. Diabetes 39: 118 –122, 1990.
46. Castegna A, Aksenov M, Thongboonkerd V, Klein JB, Pierce WM, Booze R, Markesbery WR, Butterfield DA. Proteomic identification of oxidatively modified proteins in
Alzheimer’s disease brain. Part II: dihydropyrimidinase-related protein 2, alpha-enolase and heat shock cognate 71. J Neurochem 82: 1524 –1532, 2002.
27. Betsholtz C, Christmanson L, Engström U, Rorsman F, Svensson V, Johnson KH,
Westermark P. Sequence divergence in a specific region of islet amyloid polypeptide
(IAPP) explains differences in islet amyloid formation between species. FEBS Lett 251:
261–264, 1989.
47. Chang NC, Nguyen M, Germain M, Shore GC. Antagonism of Beclin 1-dependent
autophagy by BCL-2 at the endoplasmic reticulum requires NAF-1. EMBO J 29: 606 –
618, 2010.
28. Betsholtz C, Svensson V, Rorsman F, Engström U, Westermark GT, Wilander E,
Johnson KH, Westermark P. Islet amyloid polypeptide (IAPP): cDNA cloning and
identification of an amyloidogenic region associated with species-specific occurrence
of age-related diabetes mellitus. Exp Cell Res 183: 484 – 493, 1989.
29. Bini E, Knight DP, Kaplan DL. Mapping domain structures in silks from insects and
spiders related to protein assembly. J Mol Biol 339: 27– 40, 2004.
30. Bohman S, Andersson A, King A. No differences in efficacy between noncultured and
cultured islet in reducing hyperglycemia in a nonvascularized islet graft model. Diabetes Technol Ther 8: 536 –545, 2006.
31. Bohman S, Waern I, Andersson A, King A. Transient beneficial effects of exendin-4
treatment on the function of microencapsulated mouse pancreatic islets. Cell Transplant 16: 15–22, 2007.
32. Brain SD, Wimalawansa S, MacIntyre I, Williams TJ. The demonstration of vasodilator
activity of pancreatic amylin amide in the rabbit. Am J Pathol 136: 487– 490, 1990.
48. Chapman I, Parker B, Doran S, Feinle-Bisset C, Wishart J, Lush C, Chen K, Lacerte C,
Burns C, McKay R, Weyer C, Horowitz M. Low-dose pramlintide reduced food intake
and meal duration in healthy, normal-weight subjects. Obesity 15: 1179 –1186, 2007.
49. Chavez AO, Lopez-Alvarenga JC, Tejero ME, Triplitt C, RAB, Sriwijitkamol A, Tantiwong P, Voruganti VS, Musi N, Comuzzie AG, DeFronzo RA, Folli F. Physiological and
molecular determinants of insulin action in the baboon. Diabetes 57: 899 –908, 2008.
50. Chen X, Shen J, Prywes R. The luminal domain of ATF6 senses endoplasmic reticulum
(ER) stress and causes translocation of ATF6 from the ER to the Golgi. J Biol Chem 277:
13045–13052, 2002.
51. Chisalita SI, Lindström T, Eson Jennersjö P, Paulsson JF, Westermark GT, Olsson AG,
Arnqvist HJ. Differential lipid profile and hormonal response in type 2 diabetes by
exogenous insulin aspart versus the insulin secretagogue repaglinide, at the same
glycemic control. Acta Diabetol 46: 35– 42, 2009.
52. Cho WJ, Trikha S, Jeremic AM. Cholesterol regulates assembly of human islet amyloid
polypeptide on model membranes. J Mol Biol 393: 765–775, 2009.
33. Braks JA, Martens GJ. The neuroendocrine chaperone 7B2 can enhance in vitro
POMC cleavage by prohormone convertase PC2. FEBS Lett 371: 154 –158, 1995.
53. Cho YM, Kim M, Park KS, Kim SY, Lee HK. S20G mutation of the amylin gene is
associated with a lower body mass index in Korean type 2 diabetic patients. Diab Res
Clin Pract 60: 125–129, 2003.
34. Bretherton-Watt D, Gilbey SG, Ghatei MA, Beacham J, Macrae AD, Bloom SR. Very
high concentrations of islet amyloid polypeptide are necessary to alter the insulin
response to intravenous glucose in man. J Clin Endocrinol Metab 74: 1032–1035, 1992.
54. Chong KL, Feng L, Schappert K, Meurs E, Donahue TF, Friesen JD, Hovanessian AG,
Williams BR. Human p68 kinase exhibits growth suppression in yeast and homology to
the translational regulator GCN2. EMBO J 11: 1553–1562, 1992.
35. Broderick CL, Brooke GS, DiMarchi RD, Gold G. Human and rat amylin have no
effects on insulin secretion in isolated rat pancreatic islets. Biochem Biophys Res Commun 177: 932–938, 1991.
55. Christmanson L, Rorsman F, Stenman G, Westermark P, Betsholtz C. The human islet
amyloid polypeptide (IAPP) gene. Organization, chromosomal localization and functional identification of a promoter region. FEBS Lett 267: 160 –166, 1990.
36. Bulleid NJ, Freedman RB. Defective co-translational formation of disulphide bonds in
protein disulphide-isomerase-deficient microsomes. Nature 335: 649 – 651, 1988.
56. Christopoulos G, Paxinos G, Huang XF, Beaumont K, Toga AW, Sexton PM. Comparative distribution of receptors for amylin and the related peptides calcitonin gene
related peptide and calcitonin in rat and monkey brain. Can J Physiol Pharmacol 73:
1037–1041, 1995.
37. Bursch W, Ellinger A, Gerner C, Fröhwein U, Schulte-Hermann R. Programmed cell
death (PCD). Apoptosis, autophagic PCD, or others? Ann NY Acad Sci 926: 1–12,
2000.
38. Butler AE, Jang J, Gurlo T, Carty MD, Soeller WC, Butler PC. Diabetes due to a
progressive defect in beta-cell mass in rats transgenic for human islet amyloid polypeptide (HIP Rat): a new model for type 2 diabetes. Diabetes 53: 1509 –1516, 2004.
39. Buxbaum JN. Diseases of protein conformation: what do in vitro experiments tell us
about in vivo diseases? Trends Biochem Sci 28: 585–592, 2003.
816
57. Christopoulos G, Perry KJ, Morfis M, Tilakaratne N, Gao Y, Fraser NJ, Main MJ, Foord
SM, Sexton PM. Multiple amylin receptors arise from receptor activity-modifying
protein interaction with the calcitonin receptor gene product. Mol Pharmacol 56:
235–242, 1999.
58. Chuang LM, Lee KC, Huang CN, Wu HP, Tai TY, Lin BJ. Role of S20G mutation of
amylin gene in insulin secretion, insulin sensitivity, and type II diabetes mellitus in
Taiwanese patients. Diabetologia 41: 1250 –1251, 1998.
25. Bennett RG, Hamel FG, Duckworth WC. An insulin-degrading enzyme inhibitor decreases amylin degradation, increases amylin-induced cytotoxicity, and increases amyloid formation in insulinoma cell cultures. Diabetes 52: 2315–2320, 2003.
59. Clark A. Islet amyloid: an enigma of type-2 diabetes. Diab Metabol Rev 8: 117–132,
1992.
60. Clark A, Nilsson MR. Islet amyloid: a complication of islet dysfunction or an etiological
factor in type 2 diabetes. Diabetologia 47: 157–169, 2004.
79. Deems RO, Deacon RW, Young DA. Amylin activates glycogen phosphorylase and
inactivates glycogen synthase via a cAMP-independent mechanism. Biochem Biophys
Res Commun 174: 716 –720, 1991.
80. DeFronzo RA. Pathogenesis of type 2 diabetes mellitus. Med Clin N Am 88: 787– 835,
2004.
61. Clark A, Wells CA, Buley ID, Cruickshank JK, Vanhegan RI, Matthews DR, Cooper
GJS, Holman RR, Turner RC. Islet amyloid, increased A-cells, reduced B-cells and
exocrine fibrosis: quantitative changes in the pancreas in type 2 diabetes. Diab Res 9:
151–159, 1988.
81. Degano P, Silvestre RA, Salas M, Peiro E, JM. Amylin inhibits glucose-induced insulin
secretion in a dose-dependent manner. Study in the perfused rat pancreas. Regul Pept
43: 91–96, 1993.
62. Cluck MW, Chan CY, Adrian TE. The regulation of amylin and insulin gene expression
and secretion. Pancreas 30: 1–14, 2005.
82. Delledonne A, Kouri N, Reinstatler L, Sahara T, Li L, Zhao J, Dickson DW, ErtekinTaner N, Leissring MA. Development of monoclonal antibodies and quantitative ELISAs targeting insulin-degrading enzyme. Mol Neurodegener 4: 39, 2009.
63. Cohen AS, Calkins E. Electron microscopic observations on a fibrous component in
amyloid of diverse origins. Nature 183: 1202–1203, 1959.
64. Cooper GJ, Willis AC, Clark A, Turner RC, Sim RB, Reid KBM. Purification and
characterization of a peptide from amyloid-rich pancreases of type 2 diabetic patients.
Proc Natl Acad Sci USA 84: 8628 – 8632, 1987.
66. Cooper GJS, Leighton B, Dimitriadis GD, Parry-Billings M, Kowalchuk JM, Howland K,
Rothbard JB, Willis AC, Reid KBM. Amylin found in amyloid deposits in human type 2
diabetes mellitus may be a hormone that regulates glycogen metabolism in skeletal
muscle. Proc Natl Acad Sci USA 85: 7763–7767, 1988.
67. Costes S, Huang CJ, Gurlo T, Daval M, Matveyenko AV, Rizza RA, Butler AE, Butler
PC. Beta-cell dysfunctional ERAD/ubiquitin/proteasome system in type 2 diabetes
mediated by IAPP-induced UCH-L1 deficiency. Diabetes. In press.
68. D’Alessio DA, Verchere CB, Kahn SE, Hoagland V, Baskin DG, Palmiter RD, Ensinck
JW. Pancreatic expression and secretion of human islet amyloid polypeptide in a
transgenic mouse. Diabetes 43: 1457–1461, 1994.
69. D’Este L, Casini A, Wimalawansa SJ, Renda TG. Immunohistochemical localization of
amylin in rat brainstem. Peptides 21: 1743–1749, 2000.
70. D’Este L, Wimalawansa SJ, Renda TG. Distribution of amylin-immunoreactive neurons in the monkey hypothalamus and their relationships with the histaminergic system. Arch Histol Cytol 64: 295–303, 2001.
71. Davalli AM, Maffi P, Socci C, Sanvito F, Freschi M, Bertuzzi F, Falqui L, Di Carlo V,
Pozza G, Secchi A. Insights from a successful case of intrahepatic islet transplantation
into a type 1 diabetic patient. J Clin Endocrinol Metab 85: 3847–3852, 2000.
72. Davalli AM, Perego L, Bertuzzi F, Finzi G, La Rosa S, Blau A, Placidi C, Nano R,
Gregorini L, Perego C, Capella C, Folli F. Disproportionate hyperproinsulinemia,
beta-cell restricted prohormone convertase 2 deficiency, and cell cycle inhibitors
expression by human islets transplanted into athymic nude mice: insights into nonimmune-mediated mechanisms of delayed islet graft failure. Cell Transplant 17: 1323–
1336, 2008.
73. Davenport EL, Morgan GJ, Davies FE. Untangling the unfolded protein response. Cell
Cycle 7: 865– 869, 2008.
84. Dische FE, Wernstedt C, Westermark GT, Westermark P, Pepys MB, Rennie JA,
Gilbey SG, Watkins PJ. Insulin as an amyloid-fibril protein at sites of repeated insulin
injections in a diabetic patient. Diabetologia 31: 158 –161, 1988.
85. Dobolyi A. Central amylin expression and its induction in rat dams. J Neurochem 111:
1490 –1500, 2009.
86. Dobson CM. Principles of protein folding, misfolding and aggregation. Semin Cell Dev
Biol 15: 3–16, 2004.
87. Dobson CM. Protein misfolding, evolution and disease. Trends Biochem Sci 24: 329 –
332, 1999.
88. Dodson G, Steiner D. The role of assembly in insulin’s biosynthesis. Curr Opin Struct
Biol 8: 189 –194, 1998.
89. Duckworth WC, Hamel FG. Cellular and endosomal insulin degradation. Adv Second
Messenger Phosphoprotein Res 24: 521–528, 1990.
90. Dunn WAJ. Autophagy and related mechanisms of lysosome-mediated protein degradation. Trends Cell Biol 4: 139 –143, 1994.
91. Dupuis NF, Wu C, Shea JE, Bowers MT. Human islet amyloid polypeptide monomers
form ordered beta-hairpins: a possible direct amyloidogenic precursor. J Am Chem Soc
131: 18283–18292, 2009.
92. Ebrahim A, Hamel FG, Bennett RG, Duckworth WC. Identification of the metal
associated with the insulin degrading enzyme. Biochem Biophys Res Commun 181:
1398 –1406, 1991.
93. Ehrlich JC, Ratner IM. Amyloidosis of the islets of Langerhans. A restudy of islet hyalin
in diabetic and nondiabetic individuals. Am J Pathol 38: 49 –59, 1961.
94. Eizirik DL, Björklund A, Cagliero E. Genotoxic agents increase expression of growth
arrest and DNA damage–inducible genes gadd 153 and gadd 45 in rat pancreatic islets.
Diabetes 42: 738 –745, 1993.
95. Eizirik DL, Cardozo AK, Cnop M. The role of endoplasmic reticulum stress in diabetes
mellitus. Endocr Rev 29: 42– 61, 2008.
74. Davidson HW, Hutton JC. The insulin-secretory-granule carboxypeptidase H. Purification and demonstration of involvement in proinsulin processing. Biochem J 245:
575–582, 1987.
96. Eizirik DL, Jansson L, Flodström M, Hellerström C, Andersson A. Mechanisms of
defective glucose-induced insulin release in human pancreatic islets transplanted to
diabetic nude mice. J Clin Endocrinol Metab 82: 2660 –2663, 1997.
75. De Koning EJP, Bodkin NL, Hansen BC, Clark A. Diabetes mellitus in Macaca mulatta
monkeys is characterized by islet amyloidosis and reduction in beta-cell population.
Diabetologia 36: 378 –384, 1993.
97. Eizirik DL, Pipeleers DG, Ling Z, Welsh N, Hellerström C, Andersson A. Major
species differences between humans and rodents in the susceptibility to pancreatic
beta-cell injury. Proc Natl Acad Sci USA 91: 9253–9256, 1994.
76. De Koning EPJ, Morris ER, Hofhuis FMA, Posthuma G, Höppener JWM, Morris JF,
Capel PJA, Clark A, Verbeek JS. Intra- and extracellular amyloid fibrils are formed in
cultured pancreatic islets of transgenic mice expressing human islet amyloid polypeptide. Proc Natl Acad Sci USA 91: 8467– 8471, 1994.
98. Ekberg K, Brismar T, Johansson BL, Lindström P, Juntti-Berggren L, Norrby A, Berne
C, Arnqvist HJ, Bolinder J, Wahren J. C-Peptide replacement therapy and sensory
nerve function in type 1 diabetic neuropathy. Diabetes Care 30: 71–76, 2007.
77. De Strooper B. Proteases and proteolysis in Alzheimer disease: a multifactorial view
on the disease process. Physiol Rev 90: 465– 494, 2010.
99. Emamaullee JA, Merani S, Toso C, Kin T, Al-Saif F, Truong W, Pawlick R, Davis J,
Edgar R, Lock J, Bonner-Weir S, Knudsen LB, Shapiro AM. Porcine marginal mass islet
autografts resist metabolic failure over time and are enhanced by early treatment with
liraglutide. Endocrinology 150: 2145–2152, 2009.
78. De Waal EJ, Vreeling-Sindelárová H, Schellens JP, Houtkooper JM, James J. Quantitative changes in the lysosomal vacuolar system of rat hepatocytes during short-term
starvation. A morphometric analysis with special reference to macro- and microautophagy. Cell Tissue Res 243: 641– 648, 1986.
100. Engel MF, Yigittop H, Elgersma RC, Rijkers DT, Liskamp RM, de Kruijff B, Höppener
JW, Antoinette Killian J. Islet amyloid polypeptide inserts into phospholipid monolayers as monomer. J Mol Biol 356: 783–789, 2006.
817
65. Cooper GJS. Amylin compared with calcitonin gene-related peptide: structure, biology, and relevance to metabolic disease. Endocr Rev 15: 163–201, 1994.
83. Deng S, Vatamaniuk M, Huang X, Doliba N, Lian MM, Frank A, Velidedeoglu E, Desai
NM, Koeberlein B, Wolf B, Barker CF, Naji A, Matschinsky FM, Markmann JF. Structural and functional abnormalities in the islets isolated from type 2 diabetic subjects.
Diabetes 53: 624 – 632, 2004.
WESTERMARK ET AL.
101. Engel MFM, Khemtémourian L, Kleijer CC, Meeldijk HJ, Jacobs J, Verkleij AJ, de Kruijff
B, Killian JA, Höppener JW. Membrane damage by human islet amyloid polypeptide
through fibril growth at the membrane. Proc Natl Acad Sci USA 105: 6033– 6038, 2008.
102. Enqvist S, Sletten K, Stevens FJ, Hellman U, Westermark P. Germ line origin and
somatic mutations determine the target tissues in systemic AL-amyloidosis. PLoS ONE
2: e981, 2007.
103. Esapa C, Moffitt JH, Novials A, McNamara CM, Levy JC, Laakso M, Gomis R, Clark A.
Islet amyloid polypeptide gene promoter polymorphisms are not associated with type
2 diabetes or with the severity of islet amyloidosis. Biochim Biophys Acta 1740: 74 –78,
2005.
104. Eskelinen EL. Maturation of autophagic vacuoles in mammalian cells. Autophagy 1:
1–10, 2005.
121. Glenner GG. Amyloid deposits and amyloidosis. The ␤-fibrilloses. N Engl J Med 302:
1283–1292, 1980.
122. Glenner GG, Eanes ED, Bladen HA, Linke RP, Termine JD. ␤-Pleated sheet fibrils. A
comparison of native amyloid with synthetic protein fibrils. J Histochem Cytochem 22:
1141–1158, 1974.
123. Glenner GG, Terry W, Harada M, Isersky C, Page D. Amyloid fibril proteins: proof of
homology with immunoglobulin light chains by sequence analysis. Science 172: 1150 –
1151, 1971.
124. Goldfine ID, Williams JA, Bailey AC, Wong KY, Iwamoto Y, Yokono K, Baba S, Roth
RA. Degradation of insulin by isolated mouse pancreatic acini. Evidence for cell surface
protease activity. Diabetes 33: 64 –72, 1984.
125. Goldsbury C, Goldie K, Pellaud J, Seelig J, Frey P, Müller SA, Kistler J, Cooper GJS,
Aebi U. Amyloid fibril formation from full-length and fragments of amylin. J Struct Biol
130: 352–362, 2000.
106. Farris W, Mansourian S, Leissring MA, Eckman EA, Bertram L, Eckman CB, Tanzi RE,
Selkoe DJ. Partial loss-of-function mutations in insulin-degrading enzyme that induce
diabetes also impair degradation of amyloid beta-protein. Am J Pathol 164: 1425–
1434, 2004.
126. Göpel SO, Kanno T, Barg S, Eliasson L, Galvanovskis J, Renström E, Rorsman P.
Activation of Ca2⫹-dependent K⫹ channels contributes to rhythmic firing of action
potentials in mouse pancreatic beta cells. J Gen Physiol 114: 759 –770, 1999.
107. Federici M, Hribal M, Perego L, Ranalli M, Caradonna Z, Perego C, Usellini L, Nano R,
Bonini P, Bertuzzi F, Marlier LN, Davalli AM, Carandente O, Pontiroli AE, Melino G,
Marchetti P, Lauro R, Sesti G, Folli F. High glucose causes apoptosis in cultured human
pancreatic islets of Langerhans: a potential role for regulation of specific Bcl family
genes toward an apoptotic cell death program. Diabetes 50: 1290 –1301, 2001.
127. Guardado-Mendoza R, Davalli AM, Chavez AO, Hubbard GB, Dick EJ, Majluf-Cruz A,
Tene-Perez CE, Goldschmidt L, Hart J, Perego C, Comuzzie AG, Tejero ME, Finzi G,
Placidi C, La Rosa S, Capella C, Halff G, Gastaldelli A, Defronzo RA, Folli F. Pancreatic
islet amyloidosis, ␤-cell apoptosis, and ␣-cell proliferation are determinants of islet
remodeling in type-2 diabetic baboons. Proc Natl Acad Sci USA 106: 13992–13997,
2009.
108. Finzi G, Davalli A, Placidi C, Usellini L, La Rosa S, Folli F, Capella C. Morphological and
ultrastructural features of human islet grafts performed in diabetic nude mice. Ultrastruct Pathol 29: 525–533, 2005.
109. Fonseca SG, Burcin M, Gromada J, Urano F. Endoplasmic reticulum stress in beta-cells
and development of diabetes. Curr Opin Pharmacol 9: 763–770, 2009.
110. Fox N, Schrementi J, Nishi M, Ohagi S, Chan SJ, Heisserman JA, Westermark GT,
Leckström A, Westermark P, Steiner DF. Human islet amyloid polypeptide transgenic
mice as a model of non-insulin-dependent diabetes mellitus (NIDDM). FEBS Lett 323:
40 – 44, 1993.
111. Gardiner SM, Compton AM, Kemp PA, Bennett T, Bose C, Foulkes R, Hughes B.
Antagonistic effect of human alpha-calcitonin gene-related peptide (8 –37) on regional
hemodynamic actions of rat islet amyloid polypeptide in conscious Long-Evans rats.
Diabetes 40: 948 –951, 1991.
128. Gurlo T, Ryazantsev S, Huang CJ, Yeh MW, Reber HA, Hines OJ, O’Brien TD, Glabe
CG, Butler PC. Evidence for proteotoxicity in beta cells in type 2 diabetes: toxic islet
amyloid polypeptide oligomers form intracellularly in the secretory pathway. Am J
Pathol 176: 861– 869, 2010.
129. Gylfe E, Ahmed M, Bergsten P, Dansk H, Dyachok O, Eberhardson M, Grapengiesser
E, Hellman B, Lin JM, Sundsten T, Tengholm A, Vieira E, Westerlund J. Signaling
underlying pulsatile insulin secretion. Upsala J Med Sci 105: 35–51, 2000.
130. Hach T, Forst T, Kunt T, Ekberg K, Pfützner A, Wahren J. C-peptide and its C-terminal fragments improve erythrocyte deformability in type 1 diabetes patients. Exp
Diab Res 2008: 730594, 2008.
131. Harding HP, Calfon M, Urano F, Novoa I, Ron D. Transcriptional and translational
control in the Mammalian unfolded protein response. Annu Rev Cell Dev Biol 18:
575–599, 2002.
112. Gebre-Medhin S, Mulder H, Pekny M, Westermark G, Törnell J, Westermark P,
Sundler F, Ahrén B, Betsholtz C. Increased insulin secretion and glucose tolerance in
mice lacking islet amyloid polypeptide (amylin). Biochem Biophys Res Commun 250:
271–277, 1998.
132. Harding HP, Novoa I, Zhang Y, Zeng H, Wek R, Schapira M, Ron D. Regulated
translation initiation controls stress-induced gene expression in mammalian cells.
EMBO J 6: 1099 –1108, 2000.
113. Gebre-Medhin S, Mulder H, Zhang Y, Sundler F, Betsholtz C. Reduced nociceptive
behavior in islet amyloid polypeptide (amylin) knockout mice. Brain Res 63: 180 –183,
1998.
133. Harding HP, Zhang Y, Bertolotti A, Zeng H, Ron D. Perk is essential for translational
regulation and cell survival during the unfolded protein response. Mol Cell 5: 897–904,
2000.
114. Gellerstedt N. Die elektive, insuläre (Para-)Amyloidose der Bauchspeicheldrüse. Zugleich en Beitrag zur Kenntnis der “senilen Amyloidose.” Beitr Path Anat 101: 1–13,
1938.
134. Hay DL, Christopoulos G, Christopoulos A, Poyner DR, Sexton PM. Pharmacological
discrimination of calcitonin receptor: receptor activity-modifying protein complexes.
Mol Pharmacol 67: 1655–1665, 2005.
115. Gerich JE. The genetic basis of type 2 diabetes mellitus: impaired insulin secretion
versus impaired insulin sensitivity. Endocr Rev 19: 491–503, 1998.
135. Hayakawa T, Nagai Y, Ando H, Yamashita H, Takamura T, Abe T, Nomura G, Kobayashi KI. S20G mutation of the amylin gene in Japanese patients with type 2 diabetes. Diab Res Clin Pract 49: 195–197, 2000.
116. German M, Ashcroft S, Docherty K, Edlund H, Edlund T, Goodison S, Imura H,
Kennedy G, Madsen O, Melloul D. The insulin gene promoter. A simplified nomenclature. Diabetes 44: 1002–1004, 1995.
117. German MS, Moss LG, Wang J, Rutter WJ. The insulin and islet amyloid polypeptide
genes contain similar cell-specific promoter elements that bind identical beta-cell
nuclear complexes. Mol Cell Biol 12: 1777–1788, 1992.
118. Gilead S, Gazit E. The role of the 14 –20 domain of the islet amyloid polypeptide in
amyloid formation. Exp Diab Res 2008: 256954, 2008.
136. Hebda JA, Saraogi I, Magzoub M, Hamilton AD, Miranker AD. A peptidomimetic
approach to targeting pre-amyloidogenic states in type II diabetes. Chem Biol 16:
943–950, 2009.
137. Hellman U, Wernstedt C, Westermark P, O’Brien TD, Rathbun WB, Johnson KH.
Amino acid sequence from degu islet amyloid-derived insulin shows unique sequence
characteristics. Biochem Biophys Res Commun 169: 571–577, 1990.
119. Gilead S, Wolfenson H, Gazit E. Molecular mapping of the recognition interface
between the islet amyloid polypeptide and insulin. Angew Chem Int Ed 45: 6476 – 6480,
2006.
138. Hickey AJ, Bradley JW, Skea GL, Middleditch MJ, Buchanan CM, Phillips AR, Cooper
GJ. Proteins associated with immunopurified granules from a model pancreatic islet
beta-cell system: proteomic snapshot of an endocrine secretory granule. J Proteome
Res 8: 178 –186, 2009.
120. Glabe CG. Structural classification of toxic amyloid oligomers. J Biol Chem 283:
29639 –29643, 2008.
139. Higham CE, Hull RL, Lawrie L, Shennan KI, Morris JF, Birch NP, Docherty K, Clark A.
Processing of synthetic pro-islet amyloid polypeptide (proIAPP) “amylin” by recom-
818
105. Fan L, Westermark G, Chan SJ, Steiner DF. Altered gene structure and tissue expression on islet amyloid polypeptide in the chicken. Mol Endocrinol 8: 713–721, 1994.
binant prohormone convertase enzymes, PC2 and PC 3, in vitro. Eur J Biochem 267:
4998 –5004, 2000.
140. Higham CE, Jaikaran ETAS, Fraser PE, Gross M, Clark A. Preparation of synthetic
human islet amyloid polypeptide (IAPP) in a stable conformation to enable study of
conversion to amyloid-like fibrils. FEBS Lett 470: 55– 60, 2000.
141. Hirota M, Kitagaki M, Itagaki H, Aiba S. Quantitative measurement of spliced XBP1
mRNA as an indicator of endoplasmic reticulum stress. J Toxicol Sci 31: 149 –156,
2006.
142. Hou X, Ling Z, Quartier E, Foriers A, Schuit F, Pipeleers D, Van Schravendijk C.
Prolonged exposure of pancreatic beta cells to raised glucose concentrations results
in increased cellular content of islet amyloid polypeptide precursors. Diabetologia 42:
188 –194, 1999.
143. Howard CFJ. Insular amyloidosis and diabetes mellitus in Macaca nigra. Diabetes 27:
357–364, 1978.
160. Janson J, Soeller WC, Roche PC, Nelson RT, Torchia AJ, Kreutter DK, Butler PC.
Spontaneous diabetes mellitus in transgenic mice expressing human islet amyloid
polypeptide. Proc Natl Acad Sci USA 93: 7283–7288, 1996.
161. Jansson L, Eizirik DL, Pipeleers DG, Borg LA, Hellerström C, Andersson A. Impairment of glucose-induced insulin secretion in human pancreatic islets transplanted into
diabetic nude mice. J Clin Invest 96: 721–726, 1995.
162. Jean LLC, Lee C, Shaw M, Vaux DJ. Competing discrete interfacial effects are critical
for amyloidogenesis. FASEB J 24: 309 –317, 2010.
163. Johnson KH, O’Brien TD, Betsholtz C, Westermark P. Islet amyloid, islet-amyloid
polypeptide, and diabetes mellitus. N Engl J Med 321: 513–518, 1989.
164. Johnson KH, O’Brien TD, Hayden DW, Jordan K, Ghobrial HKG, Mahoney WC,
Westermark P. Immunolocalization of islet amyloid polypeptide (IAPP) in pancreatic
beta cells by means of peroxidase-antiperoxidase (PAP) and protein A-gold techniques. Am J Pathol 130: 1– 8, 1988.
165. Johnson KH, O’Brien TD, Jordan K, Westermark P. Impaired glucose tolerance is
associated with increased islet amyloid polypeptide (IAPP) immunoreactivity in pancreatic beta cells. Am J Pathol 135: 245–250, 1989.
145. Huang CJ, Lin CY, Haataja L, Gurlo T, Butler AE, Rizza RA, Butler PC. High expression
rates of human islet amyloid polypeptide induce endoplasmic reticulum stress mediated beta-cell apoptosis, a characteristic of humans with type 2 but not type 1 diabetes. Diabetes 56: 2016 –2027, 2007.
166. Johnson KH, O’Brien TD, Jordan KH, Betsholtz C, Westermark P. The putative
hormone islet amyloid polypeptide (IAPP) induces impaired glucose tolerance in cats.
Biochem Biophys Res Commun 167: 507–513, 1990.
146. Hull RL, Westermark GT, Westermark P, Kahn SE. Islet amyloid: a critical entity
in the pathogenesis of type 2 diabetes. J Clin Endocrinol Metab 89: 3629 –3643,
2004.
147. Hull RL, Zraika S, Udayasankar J, Aston-Mourney K, Subramanian SL, Kahn SE. Amyloid formation in human IAPP transgenic mouse islets and pancreas, and human
pancreas, is not associated with endoplasmic reticulum stress. Diabetologia 52: 1102–
1111, 2009.
148. Hutton JC. The insulin secretory granule. Diabetologia 32: 271–281, 1989.
149. Hutton JC. The internal pH and membrane potential of the insulin-secretory granule.
Biochem J 204: 171–178, 1982.
150. Hutton JC, Penn EJ, Peshavaria M. Isolation and characterisation of insulin secretory
granules from a rat islet cell tumour. Diabetologia 23: 365–373, 1982.
151. Höppener JW, Ahrén B, Lips CJ. Islet amyloid and type 2 diabetes mellitus. N Engl J
Med 343: 411– 419, 2000.
152. Höppener JWM, Oosterwijk;C, Nieuwenhuis MG, Posthuma G, Thijssen JHH,
Vroom TM, Ahrén B, Lips CJM. Extensive islet amyloid formation is induced by
development of type II diabetes mellitus and contributes to its progression: pathogenesis of diabetes in a mouse model. Diabetologia 42: 427– 434, 1999.
153. Ichimura Y, Kirisako T, Takao T, Satomi Y, Shimonishi Y, Ishihara N, Mizushima N,
Tanida I, Kominami E, Ohsumi M, Noda T, Ohsumi Y. A ubiquitin-like system mediates protein lipidation. Nature 408: 488 – 492, 2000.
154. Ionescu-Tirgoviste C, Guja C. Proinsulin, proamylin and the beta cell endoplasmic
reticulum: the key for the pathogenesis of different diabetes phenotypes. Proc Rom
Acad Series B 2: 113–139, 2007.
155. Jaikaran ET, Higham CE, Serpell LC, Zurdo J, Gross M, Clark A, Fraser PE. Identification of a novel human islet amyloid polypeptide beta-sheet domain and factors
influencing fibrillogenesis. J Mol Biol 308: 515–525, 2001.
167. Johnson KH, Stevens JB. Light and electron microscopic studies of islet amyloid in
diabetic cats. Diabetes 22: 81–90, 1973.
168. Johnson KH, Wernstedt C, O’Brien TD, Westermark P. Amyloid in the pancreatic
islets of the cougar (Felis concolor) is derived from islet amyloid polypeptide (IAPP).
Comp Biochem Physiol B Comp Biochem 98: 115–119, 1991.
169. Kahn SE. The importance of the ␤-cell in the pathogenesis of type 2 diabetes. Am J Med
108: 2S– 8S, 2000.
170. Kahn SE. The relative contributions of insulin resistance and beta-cell dysfunction to
the pathophysiology of Type 2 diabetes. Diabetologia 46: 3–19, 2003.
171. Kahn SE, Andrikopoulos S, Verchere CB. Islet amyloid, a long-recognized but underappreciated pathological feature of type 2 diabetes. Diabetes 48: 241–253, 1999.
172. Kahn SE, D’Alessio DA, Schwartz MW, Fujimoto WF, Ensinck JW, Taborsky GJJ, Porte
DJ. Evidence of cosecretion of islet amyloid polypeptide and insulin by ␤-cells. Diabetes 39: 634 – 638, 1990.
173. Kahn SE, Fujimoto WY, D’Alessio DA, Ensinck JW, Porte DJ. Glucose stimulates and
potentiates islet amyloid polypeptide secretion by the B-cell. Horm Metab Res 23:
577–580, 1991.
174. Kahn SE, Zraika S, Utzschneider KM, Hull RL. The beta cell lesion in type 2 diabetes:
there has to be a primary functional abnormality. Diabetologia 52: 1003–1012, 2009.
175. Kajava AV, Aebi U, Steven AC. The parallel superpleated beta-structure as a model
for amyloid fibrils of human amylin. J Mol Biol 248: 247–252, 2005.
176. Kapurniotu A, Schmauder A, Tenidis K. Structure-based design and study of nonamyloidogenic, double N-methylated IAPP amyloid core sequences as inhibitors of
IAPP amyloid formation and cytotoxicity. J Mol Biol 315: 339 –350, 2002.
177. Karlsson E. IAPP as a regulator of glucose homeostasis and pancreatic hormone
secretion. Int J Mol Med 3: 577–584, 1999.
156. Jaikaran ETAS, Clark A. Islet amyloid and type 2 diabetes: from molecular misfolding
to islet pathophysiology. Biochim Biophys Acta 1537: 179 –203, 2001.
178. Kawahara M, Kuroda Y, Arispe N, Rojas E. Alzheimer’s beta-amyloid, human islet
amylin, and prion protein fragment evoke intracellular free calcium elevations by a
common mechanism in a hypothalamic GnRH neuronal cell line. J Biol Chem 275:
14077–14083, 2000.
157. Jaikaran ETAS, Nilsson MR, Clark A. Pancreatic ␤-cell granule peptides form heteromolecular complexes which inhibit islet amyloid polypeptide fibril formation. Biochem
J 377: 709 –716, 2004.
179. Kayed R, Bernhagen J, Greenfield N, Sweimeh K, Brunner H, Voelter W, Kapurniotu
A. Conformational transitions of islet amyloid polypeptide (IAPP) in amyloid formation in vitro. J Mol Biol 287: 781–796, 1999.
158. Janciauskiene S, Eriksson S, Carlemalm E, Ahrén B. B cell granule peptides affect
human islet amyloid polypeptide (IAPP) fibril formation in vitro. Biochem Biophys Res
Commun 236: 580 –585, 1997.
180. Kayed R, Head E, Thompson JL, McIntire TM, Milton SC, Cotman CW, Glabe CG.
Common structure of soluble amyloid oligomers implies common mechanism of
pathogenesis. Science 300: 486 – 489, 2003.
159. Janson J, Ashley RH, Harrison D, McIntyre S, Butler PC. The mechanism of islet
amyloid polypeptide toxicity is membrane disruption by intermediate-sized toxic
amyloid particles. Diabetes 48: 491– 498, 1999.
181. Kayed R, Pensalfini A, Margol L, Sokolov Y, Sarsoza F, Head E, Hall JE, Glabe C.
Annular protofibrils are a structurally and functionally distinct type of amyloid oligomer. J Biol Chem 284: 4230 – 4237, 2009.
819
144. Howard CFJ. Longitudinal studies on the development of diabetes in individual
Macaca nigra. Diabetologia 29: 301–306, 1986.
WESTERMARK ET AL.
182. Kemp CB, Knight MJ, Scharp DW, Ballinger WF, Lacy PE. Effect of transplantation site
on the results of pancreatic islet isografts in diabetic rats. Diabetologia 9: 486 – 491,
1973.
203. Lee AH, Iwakoshi NN, Glimcher LH. XBP-1 regulates a subset of endoplasmic reticulum resident chaperone genes in the unfolded protein response. Mol Cell Biol 23:
7448 –7459, 2003.
183. Khan MH, Harlan DM. Counterpoint: clinical islet transplantation: not ready for prime
time. Diabetes Care 32: 1570 –1574, 2009.
204. Lee SC, Hashim Y, Li JKY, Ko GTC, Critchley JAJH, Cockram CS, Chan JCN. The islet
amyloid polypeptide (amylin) gene S20G mutation in Chinese subjects: evidence for
associations with type 2 diabetes and cholesterol levels. Clin Endocrinol 54: 541–546,
2001.
184. Khemtémourian L, Killian JA, Höppener JWM, Engel MFM. Recent insights in islet
amyloid polypeptide-induced membrane disruption and its role in ␤-cell death in type
2 diabetes mellitus. Exp Diab Res 2008: 1–9, 2008.
185. Khemtémourian L, Lahoz Casarramona G, Suylen DPL, Hackeng TM, Meeldijk JD, de
Kruijff B, Höppener JWM, Killian JA. Impaired processing of human pro-islet amyloid
polypeptide is not a causative factor for fibril formation or membrane damage in vitro.
Biochemistry 48: 10918 –10925, 2009.
187. Kirkin V, Lamark T, Johansen T, Dikic I. NBR1 cooperates with p62 in selective
autophagy of ubiquitinated targets. Autophagy 5: 732–733, 2009.
188. Klöppel G, Drenck CR. Immunzytochemische Morphometrie beim Typ-1- und Typ2-Diabetes mellitus. Deutsch Med Wschr 108: 188 –189, 1983.
189. Klunk WE, Engler H, Nordberg A, Wang Y, Blomqvist G, Holt DP, Bergström M,
Savitcheva I, Huang GF, Estrada S, Ausén B, Debnath ML, Barletta J, Price JC, Sandell
J, Lopresti BJ, Wall A, Koivisto P, Antoni G, Mathis CA, La˚ngström B. Imaging brain
amyloid in Alzheimer’s disease with Pittsburgh Compound-B. Ann Neurol 55: 306 –
319, 2004.
190. Knight JD, Hebda JA, Miranker AD. Conserved and cooperative assembly of membrane-bound a-helical states of islet amyloid polypeptide. Biochemistry 45: 9496 –
9508, 2006.
191. Kogire M, Ishizuka J, Thompson JC, Greeley GHJ. Inhibitory action of islet amyloid
polypeptide and calcitonin gene-related peptide on release of insulin from the isolated
perfused rat pancreas. Pancreas 6: 459 – 463, 1991.
192. Koo BW, Miranker AD. Contribution of the intrinsic disulfide to the assembly mechanism of islet amyloid. Protein Sci 14: 231–239, 2005.
193. Korsgren O, Jansson L, Andersson A. Effects of hyperglycemia on function of isolated
mouse pancreatic islets transplanted under kidney capsule. Diabetes 38: 510 –515,
1989.
194. Korsgren O, Sandler S, Landström AS, Jansson L, Andersson A. Large-scale production of fetal porcine pancreatic isletlike cell clusters. An experimental tool for studies
of islet cell differentiation and xenotransplantation. Transplantation 45: 509 –514,
1988.
195. Kudva YC, Mueske C, Butler PC, Eberhardt NL. A novel assay in vitro of human islet
amyloid polypeptide amyloidogenesis and effects of insulin secretory vesicle peptides
on amyloid formation. Biochem J 331: 809 – 813, 1998.
196. Lacy PE. The pancreatic beta cell. Structure and function. N Engl J Med 276: 187–195,
1967.
197. Lang DA, Matthews DR, Peto J, Turner RC. Cyclic oscillations of basal plasma glucose
and insulin concentrations in human beings. N Engl J Med 301: 1023–1027, 1979.
198. Larsen CN, Krantz BA, Wilkinson KD. Substrate specificity of deubiquitinating enzymes: ubiquitin C-terminal hydrolases. Biochemistry 37: 3358 –3368, 1998.
199. Larson JL, Miranker AD. The mechanism of insulin action on islet amyloid polypeptide
fiber formation. J Mol Biol 335: 221–231, 2004.
200. Lashuel HA, Hartley D, Petre BM, Walz T, Lansbury PTJ. Neurodegenerative disease:
amyloid pores from pathogenic mutations. Nature 418: 291, 2002.
206. Leissring MA, Farris W, Chang AY, Walsh DM, Wu X, Sun X, Frosch MP, Selkoe DJ.
Enhanced proteolysis of beta-amyloid in APP transgenic mice prevents plaque formation, secondary pathology, and premature death. Neuron 40: 1087–1093, 2003.
207. Leissring MA, Farris W, Wu X, Christodoulou DC, Haigis MC, Guarente L, Selkoe DJ.
Alternative translation initiation generates a novel isoform of insulin-degrading enzyme targeted to mitochondria. Biochem J 383: 439 – 446, 2004.
208. Lesné S, Koh MT, Kotilinek L, Kayed R, Glabe CG, Yang A, Gallagher M, Ashe KH. A
specific amyloid-beta protein assembly in the brain impairs memory. Nature 440:
352–357, 2006.
209. Lin CY, Gurlo T, Kayed R, Butler AE, Haataja L, Glabe CG, Butler PC. Toxic human
islet amyloid polypeptide (h-IAPP) oligomers are intracellular, and vaccination to
induce anti-toxic oligomer antibodies does not prevent h-IAPP-induced beta-cell apoptosis in h-IAPP transgenic mice. Diabetes 56: 1324 –1332, 2007.
210. Llorens-Cortes C, Giros B, Schwartz JC. A novel potential metallopeptidase derived
from the enkephalinase gene by alternative splicing. J Neurochem 55: 2146 –2148,
1990.
211. Lorenzo A, Razzaboni B, Weir GC, Yankner BA. Pancreatic islet cell toxicity of amylin
associated with type-2 diabetes mellitus. Nature 368: 756 –760, 1994.
212. Lorenzo A, Yankner BA. Amyloid fibril toxicity in Alzheimer’s disease and diabetes.
Ann NY Acad Sci 777: 89 –95, 1996.
213. Luca S, Yau WM, Leapman R, Tycko R. Peptide conformation and supramolecular
organization in amylin fibrils: constraints from solid-state NMR. Biochemistry 46:
13505–13522, 2007.
214. Ludwig G, Heitner H. Zur Häufigkeit der Inselamyloidose des Pankreas beim Diabetes mellitus. Zschr Inn Med 22: 814 – 818, 1967.
215. Ludvik B, Clodi M, Kautzky-Willer A, Schuller M, Graf H, Hartter E, Pacini G, Prager
R. Increased levels of circulating islet amyloid polypeptide in patients with chronic
renal failure have no effect on insulin secretion. J Clin Invest 94: 2045–2050, 1994.
216. Lukinius A, Wilander E, Westermark GT, Engström U, Westermark P. Co-localization
of islet amyloid polypeptide and insulin in the B cell secretory granules of the human
pancreatic islets. Diabetologia 32: 240 –244, 1989.
217. Lutz TA. Amylinergic control of food intake. Physiol Behav 89: 465– 471, 2006.
218. Lutz TA, Del Prete E, Scharrer E. Reduction of food intake in rats by intraperitoneal
injection of low doses of amylin. Physiol Behav 55: 891– 895, 1994.
219. Ma Z, Westermark GT, Johnson KH, O’Brien TD, Westermark P. Quantitative immunohistochemical analysis of islet amyloid polypeptide (IAPP) in normal, impaired
glucose tolerant, and diabetic cats. Amyloid 54: 255–261, 1998.
220. Ma Z, Westermark GT, Li ZC, Engström U, Westermark P. Altered immunoreactivity
of islet amyloid polypeptide (IAPP) may reflect major modifications of the IAPP molecule in the amyloidogenesis. Diabetologia 40: 793– 801, 1997.
221. Ma Z, Westermark GT, Sakagashira S, Sanke T, Gustavsson Å, Sakamoto H, Engström
U, Nanjo K, Westermark P. Enhanced in vitro production of amyloid-like fibrils from
mutant (S20G) islet amyloid polypeptide. Amyloid 8: 242–249, 2001.
222. MacIntyre I. Amylinamide, bone conservation, and pancreatic beta cells. Lancet 2:
1026 –1027, 1989.
201. Laybutt DR, Preston AM, Akerfeldt MC, Kench JG, Busch AK, Biankin AV, Biden TJ.
Endoplasmic reticulum stress contributes to beta cell apoptosis in type 2 diabetes.
Diabetologia 50: 752–763, 2007.
223. Maclean N, Ogilvie RF. Quantitative estimation of the pancreatic islet tissue in diabetic
subjects. Diabetes 4: 367–376, 1955.
202. Leckström A, Björklund K, Permert J, Larsson R, Westermark P. Renal elimination of
islet amyloid polypeptide. Biochem Biophys Res Commun 239: 265–268, 1997.
224. Maiuri MC, Le Toumelin G, Criollo A, Rain JC, Gautier F, Juin P, Tasdemir E, Pierron
G, Troulinaki K, Tavernarakis N, Hickman JA, Geneste O, Kroemer G. Functional and
820
186. Kirisako T, Ichimura Y, Okada H, Kabeya Y, Mizushima N, Yoshimori T, Ohsumi M,
Takao T, Noda T, Ohsumi Y. The reversible modification regulates the membranebinding state of Apg8/Aut7 essential for autophagy and the cytoplasm to vacuole
targeting pathway. J Cell Biol 151: 263–276, 2000.
205. Lee SN, Prodhomme E, Lindberg I. Prohormone convertase 1 (PC1) processing and
sorting: effect of PC1 propeptide and proSAAS. J Endocrinol 182: 353–364, 2004.
physical interaction between Bcl-X(L) and a BH3-like domain in Beclin-1. EMBO J 26:
2527–2539, 2007.
245. Mineo D, Pileggi A, Alejandro R, Ricordi C. Point: steady progress and current challenges in clinical islet transplantation. Diabetes Care 32: 1563–1569, 2009.
225. Maji SK, Perrin MH, Sawaya MR, Jessberger S, Vadodaria K, Rissman RA, Singru PS,
Nilsson KP, Simon R, Schubert D, Eisenberg D, Rivier J, Sawchenko P, Vale W, Riek R.
Functional amyloids as natural storage of peptide hormones in pituitary secretory
granules. Science 328 –332, 2009.
246. Mirzabekov TA, Lin M, Kagan BL. Pore formation by the cytotoxic islet amyloid
peptide amylin. J Biol Chem 271: 1988 –1992, 1996.
226. Maloy AL, Longnecker DS, Greenberg ER. The relation of islet amyloid to the clinical
type of diabetes. Hum Pathol 12: 917–922, 1981.
227. Marchetti P, Bugliani M, Lupi R, Marselli L, Masini M, Boggi U, Filipponi F, Weir GC,
Eizirik DL, Cnop M. The endoplasmic reticulum in pancreatic beta cells of type 2
diabetes patients. Diabetologia 50: 2486 –2494, 2007.
247. Miyazato M, Nakazato M, Shiomi K, Aburaya J, Kangawa K, Matsuo H, Matsukura S.
Molecular forms of islet amyloid polypeptide (IAPP/amylin) in four mammals. Diab Res
Clin Pract 31–36, 1992.
248. Miyazato M, Nakazato M, Shiomi K, Aburaya J, Toshimori H, Kangawa K, Matsuo H,
Matsukura S. Identification and characterization of islet amyloid polypeptide in mammalian gastrointestinal tract. Biochem Biophys Res Commun 181: 293–300, 1991.
249. Mizushima N, Yamamoto A, Matsui M, Yoshimori T, Ohsumi Y. In vivo analysis of
autophagy in response to nutrient starvation using transgenic mice expressing a fluorescent autophagosome marker. Mol Biol Cell 15: 1101–1111, 2004.
229. Marr RA, Guan H, Rockenstein E, Kindy M, Gage FH, Verma I, Masliah E, Hersh LB.
Neprilysin regulates amyloid beta peptide levels. J Mol Neurosci 22: 5–11, 2004.
250. Mizushima N, Yoshimori T, Ohsumi Y. Role of the Apg12 conjugation system in
mammalian autophagy. Int J Biochem Cell Biol 35: 553–561, 2003.
230. Martínez-Álvarez RM, Volkoff H, Munoz Cueto JA, Delgado MJ. Molecular characterization of calcitonin gene-related peptide (CGRP) related peptides (CGRP, amylin,
adrenomedullin and adrenomedullin-2/intermedin) in goldfish (Carassius auratus):
cloning and distribution. Peptides 29: 1534 –1543, 2008.
251. Mohajeri MH, Wollmer MA, Nitsch RM. Abeta 42-induced increase in neprilysin is
associated with prevention of amyloid plaque formation in vivo. J Biol Chem 277:
35460 –35465, 2002.
231. Martínez A, Kapas S, Miller M, Ward Y, Cuttitta F. Coexpression of receptors for
adrenomedullin, calcitonin gene-related peptide, and amylin in pancreatic beta-cells.
Endocrinology 141: 406 – 411, 2000.
232. Marx J. Alzheimer’s debate boils over. Science 257: 1336 –1338, 1992.
233. Marzban L, Tomas A, Becker TC, Rosenberg L, Oberholzer J, Fraser PE, Halban PA,
Verchere CB. Small interfering RNA-mediated suppression of proislet amyloid polypeptide expression inhibits islet amyloid formation and enhances survival of human
islets in culture. Diabetes 57: 3045–3055, 2008.
234. Marzban L, Trigo-Gonzalez G, Zhu X, Rhodes CJ, Halban PA, Steiner DF, Verchere
CB. Role of beta-cell prohormone convertase (PC)1/3 in processing of pro-islet amyloid polypeptide. Diabetes 53: 141–148, 2004.
235. Masini M, Bugliani M, Lupi R, del Guerra S, Boggi U, Filipponi F, Marselli L, Masiello P,
Marchetti P. Autophagy in human type 2 diabetes pancreatic beta cells. Diabetologia
52: 1083–1086, 2009.
236. Masters C, Simms G, Weinman NA, Multhaup G, McDonald BL, Beyreuther K. Amyloid plaque core protein in Alzheimer disease and Down syndrome. Proc Natl Acad
Sci USA 82: 4245– 4249, 1985.
237. Masters SL, Dunne A, Subramanian SL, Hull RL, Tannahill GM, Sharp FA, Becker C,
Franchi L, Yoshihara E, Chen Z, Mullooly N, Mielke LA, Harris J, Coll RC, Mills KH,
Mok KH, Newsholme P, Nuñez G, Yodoi J, Kahn SE, Lavelle EC, O’Neill LA. Activation of the NLRP3 inflammasome by islet amyloid polypeptide provides a mechanism
for enhanced IL-1␤ in type 2 diabetes. Nat Immunol 11: 897–904, 2010.
238. Matsumoto M, Minami M, Takeda K, Sakao Y, Akira S. Ectopic expression of CHOP
(GADD153) induces apoptosis in M1 myeloblastic leukemia cells. FEBS Lett 395:
143–147, 1996.
239. Matveyenko AV, Butler PC. Beta-cell deficit due to increased apoptosis in the human
islet amyloid polypeptide transgenic (HIP) rat recapitulates the metabolic defects
present in type 2 diabetes. Diabetes 55: 2106 –2114, 2006.
240. Matveyenko AV, Butler PC. Islet amyloid polypeptide (IAPP) transgenic rodents as
models for type 2 diabetes. ILAR J 47: 225–233, 2006.
241. McLatchie LM, Fraser NJ, Main MJ, Wise A, Brown J, Thompson N, Solari R, Lee MG,
Foord SM. RAMPs regulate the transport and ligand specificity of the calcitoninreceptor-like receptor. Nature 393: 333–339, 1998.
242. Mellgren A, Schnell Landström AH, Petersson B, Andersson A. The renal subcapsular
site offers better growth conditions for transplanted mouse pancreatic islet cells than
the liver or spleen. Diabetologia 29: 670 – 672, 1986.
243. Merlini G, Bellotti V. Molecular mechanisms of amyloidosis. N Engl J Med 349: 583–
596, 2003.
244. Merlini G, Westermark P. The systemic amyloidosis: clearer understanding of the
molecular mechanisms offer hope for more effective therapies. J Intern Med 255:
159 –178, 2004.
252. Morfis M, Tilakaratne N, Furness SG, Christopoulos G, Werry TD, Christopoulos A,
Sexton PM. Receptor activity-modifying proteins differentially modulate the G protein-coupling efficiency of amylin receptors. Endocrinology 149: 5423–5431, 2008.
253. Morita M, Kurochkin IV, Motojima K, Goto S, Takano T, Okamura S, Sato R, Yokota
S. Insulin-degrading enzyme exists inside of rat liver peroxisomes and degrades oxidized proteins. Cell Struct Funct 25: 309 –315, 2000.
254. Mosselman S, Höppener JWM, Lips CJM, Jansz HS. The complete islet amyloid polypeptide precursor is encoded by two exons. FEBS Lett 247: 154 –158, 1989.
255. Muff R, Bühlmann N, Fischer JA, Born W. An amylin receptor is revealed following
co-transfection of a calcitonin receptor with receptor activity modifying proteins-1 or
-3. Endocrinology 140: 2924 –2927, 1999.
256. Mulder H, Ahrén B, Sundler F. Differential expression of islet amyloid polypeptide
(amylin) and insulin in experimental diabetes in rodents. Mol Cell Endocrinol 114:
101–109, 1995.
257. Mulder H, Ahrén B, Sundler F. Islet amyloid polypeptide and insulin gene expression
are regulated in parallel by glucose in vivo in rats. Am J Physiol Endocrinol Metab 271:
E1008 –E1014, 1996.
258. Mulder H, Ekelund M, Ekblad E, Sundler F. Islet amyloid polypeptide in the gut and
pancreas: localization, ontogeny and gut motility effects. Peptides 18: 771–783, 1997.
259. Mulder H, Leckström A, Uddman R, Ekblad E, Westermark P, Sundler F. Islet amyloid
polypeptide (amylin) is expressed in sensory neurons. J Neurosci 15: 7625–7632,
1995.
260. Mulder H, Lindh AC, Ekblad E, Westermark P, Sundler F. Islet amyloid polypeptide is
expressed in endocrine cells of the gastric mucosa in the rat and mouse. Gastroenterology 107: 712–719, 1994.
261. Muthusamy K, Arvidsson PI, Govender P, Kruger HG, Maguire GE, Govender T.
Design and study of peptide-based inhibitors of amylin cytotoxicity. Bioorg Med Chem
Lett 20: 1360 –1362, 2010.
262. Nadal A, Quesada I, Soria B. Homologous and heterologous asynchronicity between
identified alpha-, beta- and delta-cells within intact islets of Langerhans in the mouse.
J Physiol 517: 85–93, 1999.
263. Nakagawa T, Zhu H, Morishima N, Li E, Xu J, Yankner BA, Yuan J. Caspase-12
mediates endoplasmic-reticulum-specific apoptosis and cytotoxicity by amyloid-beta.
Nature 403: 98 –103, 2000.
264. Nakazato M, Asai J, Miyazato M, Matsukura S, Kangawa K, Matsuo H. Isolation and
identification of islet amyloid polypeptide in normal human pancreas. Regul Pept 31:
179 –186, 1990.
265. Nanga RPR, Brender JR, Xu J, Hartman K, Subramanian V, Ramamoorthy A. Threedimensional structure and orientation of rat islet amyloid polypeptide protein in a
membrane environment by solution NMR spectroscopy. J Am Chem Soc 131: 8252–
8261, 2009.
821
228. Marciniak SJ, Ron D. Endoplasmic reticulum stress signaling in disease. Physiol Rev 86:
1133–1149, 2006.
WESTERMARK ET AL.
266. Naot D, Cornish J. The role of peptides and receptors of the calcitonin family in the
regulation of bone metabolism. Bone 43: 813– 818, 2008.
288. Patil SM, Xu S, Sheftic SR, Alexandrescu AT. Dynamic a-helix structure of micellebound human amylin. J Biol Chem 284: 11982–11991, 2009.
267. Nilsson MR, Raleigh DP. Analysis of amylin cleavage products provides new insights
into the amyloidogenic region of human amylin. J Mol Biol 294: 1375–1385, 1999.
289. Pattingre S, Tassa A, Qu X, Garuti R, Liang XH, Mizushima N, Packer M, Schneider
MD, Levine B. Bcl-2 antiapoptotic proteins inhibit Beclin 1-dependent autophagy. Cell
122: 927–939, 2005.
268. Nishi M, Chan SJ, Nagamatsu S, Bell GI, Steiner DF. Conservation of the sequence of
islet amyloid polypeptide in five mammals is consistent with its putative role as an islet
hormone. Proc Natl Acad Sci USA 86: 5738 –5742, 1989.
269. Nishi M, Sanke T, Seino S, Eddy RL, Fan YS, Byers MG, Shows TB, Bell GI, Steiner DF.
Human islet amyloid polypeptide gene: complete nucleotide sequence, chromosomal
localization, and evolutionary history. Mol Endocrinol 3: 1775–1781, 1989.
270. Nishi M, Steiner DF. Cloning of complementary DNAs encoding islet amyloid polypeptide, insulin, and glucagon precursors from a new world rodent, the degu, Octodon
degus. Mol Endocrinol 4: 1192, 1990.
271. Nixon RA. Autophagy, amyloidogenesis and Alzheimer disease. J Cell Science 120:
4081– 4091, 2007.
290. Paulsson JF, Andersson A, Westermark P, Westermark GT. Intracellular amyloid-like
deposits contain unprocessed pro islet amyloid polypeptide (proIAPP) in beta-cells of
transgenic mice overexpressing human IAPP and transplanted human islets. Diabetologia 49: 1237–1246, 2006.
291. Paulsson JF, Westermark GT. Aberrant processing of human proislet amyloid polypeptide results in increased amyloid production. Diabetes 54: 2117–2125, 2005.
292. Paulsson JF, Westermark GT. Differences in distribution of insulin and IAPP on the
cellular level. In: Amyloid and Amyloidosis. The Proceedings of the XIth International
Symposium on Aamyloidosis, edited by B´ely M, Apáthy Á. Budapest: Hungarian Academy of Science, 2001, p. 424 – 426.
293. Paxinos G, Chai SY, Christopoulos G, Huang XF, Toga AW, Wang HQ, Sexton PM. In
vitro autoradiographic localization of calcitonin and amylin binding sites in monkey
brain. J Chem Neuroanat 27: 217–236, 2004.
273. Novials A, Kistauri A, Chico A, Gomis R, Poa NR, Cooper GJS, Edgar PF. Amylin gene
promoter mutations predispose to Type 2 diabetes in New Zealand Maori. Diabetologia 46: 1708 –1709, 2003.
294. Pearse AGE, Ewen SWB, Polak JM. The genesis of apudamyloid in endocrine polypeptide tumours: histochemical distinction from immunamyloid. Virchows Arch Abt B
Zellpath 10: 93–107, 1972.
274. Novials A, Rojas I, Casamitjana R, Usac EF, Gomis R. A novel mutation in islet amyloid
polypeptide (IAPP) gene promoter is associated with Type II diabetes mellitus. Diabetologia 44: 1064 –1065, 2001.
295. Pepys MB. Amyloidosis. Annu Rev Med 57: 223–241, 2006.
275. O’Brien T, Westermark P, Johnson KH. Islet amyloid polypeptide and insulin secretion from isolated perfused pancreas of fed, fasted, glucose-treated, and dexamethasone-treated rats. Diabetes 40: 1701–1706, 1991.
276. O’Brien TD, Butler AE, Roche PC, Johnson KH, Butler PC. Islet amyloid polypeptide
in human insulinomas. Evidence for intracellular amyloidogenesis. Diabetes 43: 329 –
336, 1994.
277. O’Brien TD, Hayden DW, Johnson KH, Fletcher TF. Immunohistochemical morphometry of pancreatic endocrine cells in diabetic, normoglycaemic glucose-intolerant and normal cats. J Comp Pathol 96: 357–369, 1986.
278. O’Brien TD, Hayden DW, Johnson KH, Stevens JB. High dose intravenous glucose
tolerance test and serum insulin and glucagon levels in diabetic and non-diabetic cats:
relationships to insular amyloidosis. Vet Pathol 22: 250 –261, 1985.
279. O’Brien TD, Westermark P, Johnson KH. Islet amyloid polypeptide (IAPP) does not
inhibit glucose-stimulated insulin secretion from isolated perfused rat pancreas.
Biochem Biophys Res Commun 170: 1223–1228, 1990.
280. Ohlsson H, Karlsson K, Edlund T. IPF1, a homeodomain-containing transactivator of
the insulin gene. EMBO J 12: 4251– 4259, 1993.
281. Ohsumi Y. Molecular dissection of autophagy: two ubiquitin-like systems. Nat Rev Mol
Cell Biol 23: 211–216, 2001.
282. Opie EL. On relation of chronic interstitial pancreatitis to the islands of Langerhans
and to diabetes mellitus. J Exp Med 5: 397– 428, 1901.
283. Oyadomari S, Araki E, Mori M. Endoplasmic reticulum stress-mediated apoptosis in
pancreatic beta-cells. Apoptosis 7: 335–345, 2002.
296. Pettersson M, Ahrén B. Failure of islet amyloid polypeptide to inhibit basal and glucose-stimulated insulin secretion in model experiments in mice and rats. Acta Physiol
Scand 138: 389 –394, 1990.
297. Pickford F, Masliah E, Britschgi M, Lucin K, Narasimhan R, Jaeger PA, Small S, Spencer
B, Rockenstein E, Levine B, Wyss-Coray T. The autophagy-related protein beclin 1
shows reduced expression in early Alzheimer disease and regulates amyloid beta
accumulation in mice. J Clin Invest 118: 2190 –2199, 2008.
298. Poa NR, Cooper GJ, Edgar PF. Amylin gene promoter mutations predispose to Type
2 diabetes in New Zealand Maori. Diabetologia 46: 574 –578, 2003.
299. Porat Y, Kolusheva S, Jelinek R, Gazit E. The human islet amyloid polypeptide forms
transient membrane-active prefibrillar assemblies. Biochemistry 42: 10971–10977,
2003.
300. Potter KJ, Abedini A, Marek P, Klimek AM, Butterworth S, Driscoll M, Baker R,
Nilsson MR, Warnock GL, Oberholzer J, Bertera S, Trucco M, Korbutt GS, Fraser PE,
Raleigh DP, Verchere CB. Islet amyloid deposition limits the viability of human islet
grafts but not porcine islet grafts. Proc Natl Acad Sci USA 107: 4305– 4310, 2010.
301. Potter KJ, Scrocchi LA, Warnock GL, Ao Z, Younker MA, Rosenberg L, Lipsett M,
Verchere CB, Fraser PE. Amyloid inhibitors enhance survival of cultured human islets.
Biochim Biophys Acta 1790: 566 –574, 2009.
302. Poyner DR, Sexton PM, Marshall I, Smith DM, Quirion R, Born W, Muff R, Fischer JA,
Foord SM. International Union of Pharmacology. XXXII. The mammalian calcitonin
gene-related peptides, adrenomedullin, amylin, and calcitonin receptors. Pharmacol
Rev 54: 233–246, 2002.
303. Preston AM, Gurisik E, Bartley C, Laybutt DR, Biden TJ. Reduced endoplasmic reticulum (ER)-to-Golgi protein trafficking contributes to ER stress in lipotoxic mouse beta
cells by promoting protein overload. Diabetologia 52: 2369 –2373, 2009.
284. Padrick SB, Miranker AD. Islet amyloid polypeptide: identification of long-range contacts and local order on the fibrillogenesis pathway. J Mol Biol 308: 783–794, 2001.
304. Qi D, Cai K, Wang O, Li Z, Chen J, Deng B, Qian L, Le Y. Fatty acids induce amylin
expression and secretion by pancreatic ␤-cells. Am J Physiol Endocrinol Metab 298:
E99 –E107, 2010.
285. Panagiotidis G, Salehi AA, Westermark P, Lundquist I. Homologous islet amyloid
polypeptide: effects on plasma levels of glucagon, insulin and glucose in the mouse.
Diabetes Res Clin Pract 18: 167–171, 1992.
305. Quist A, Doudevski I, Lin H, Azimova R, Ng D, Frangione B, Kagan B, Ghiso J, Lal R.
Amyloid ion channels: a common structural link for protein-misfolding disease. Proc
Natl Acad Sci USA 102: 10427–10432, 2005.
286. Pankiv S, Clausen TH, Lamark T, Brech A, Bruun JA, Outzen H, Øvervatn A, Bjørkøy
G, Johansen T. p62/SQSTM1 binds directly to Atg8/LC3 to facilitate degradation of
ubiquitinated protein aggregates by autophagy. J Biol Chem 282: 24131–24145, 2007.
306. Ravier MA, Güldenagel M, Charollais A, Gjinovci A, Caille D, Söhl G, Wollheim CB,
Willecke K, Henquin JC, Meda P. Loss of connexin36 channels alters beta-cell coupling, islet synchronization of glucose-induced Ca2⫹ and insulin oscillations, and basal
insulin release. Diabetes 54: 1798 –1807, 2005.
287. Parks JK, Smith TS, Trimmer PA, Bennett JPJ, Parker WDJ. Neurotoxic Abeta peptides increase oxidative stress in vivo through NMDA-receptor and nitric-oxidesynthase mechanisms, and inhibit complex IV activity and induce a mitochondrial
permeability transition in vitro. J Neurochem 76: 1050 –1056, 2001.
822
307. Reidelberger RD, Arnelo U, Granqvist L, Permert J. Comparative effects of amylin and
cholecystokinin on food intake and gastric emptying in rats. Am J Physiol Regul Integr
Comp Physiol 280: R605–R611, 2001.
272. Nolan C, Margoliash E, Peterson JD, Steiner DF. The structure of bovine proinsulin. J
Biol Chem 246: 2780 –2795, 1971.
308. Rickels MR, Collins HW, Naji A. Amyloid and transplanted islets. N Engl J Med 359:
2729 –2731, 2008.
309. Ritzel RA, Meier JJ, Lin CY, Veldhuis JD, Butler PC. Human islet amyloid polypeptide
oligomers disrupt cell coupling, induce apoptosis, and impair insulin secretion in isolated human islets. Diabetes 56: 65–71, 2007.
310. Rochet JC, Lansbury PTJ. Amyloid fibrillogenesis: themes and variations. Curr Opin
Struct Biol 10: 60 – 68, 2000.
311. Röcken C, Linke RP, Saeger W. Immunohistology of islet amyloid polypeptide in
diabetes mellitus: semi-quantitative studies in a post-mortem series. Virchows Archiv A
421: 339 –344, 1992.
312. Roh J, Chang CL, Bhalla A, Klein C, Hsu SY. Intermedin is a calcitonin/calcitonin
gene-related peptide family peptide acting through the calcitonin receptor-like receptor/receptor activity-modifying protein receptor complexes. J Biol Chem 279: 7264 –
7274, 2004.
314. Saito K, Yaginuma N, Takahashi T. Differential volumetry of A, B and D cells in the
pancreatic islets of diabetic and nondiabetic subjects. Tohoku J Exp Med 129: 273–283,
1979.
329. Shang F, Gong X, Taylor A. Activity of ubiquitin-dependent pathway in response to
oxidative stress. Ubiquitin-activating enzyme is transiently up-regulated. J Biol Chem
272: 23086 –23093, 1997.
330. Shapiro AMJ, Lakey JRT, Ryan EA, Korbutt GS, Toth EL, Warnock GL, Kneteman NM,
Rajotte RV. Islet transplantation in seven patients with type 1 diabetes mellitus using a
glucocorticoid free immunosuppressive regiment. N Engl J Med 343: 230 –238, 2000.
331. Silvestre RA, Rodríguez-Gallardo J, Gutiérrez E, Marco J. Influence of glucose concentration on the inhibitory effect of amylin on insulin secretion. Study in the perfused rat
pancreas. Regul Pept 68: 31–35, 1997.
332. Silvestre RA, Rodríguez-Gallardo J, Jodka C, Parkes DG, Pittner RA, Young AA, Marco
J. Selective amylin inhibition of the glucagon response to arginine is extrinsic to the
pancreas. Am J Physiol Endocrinol Metab 280: E443–E449, 2001.
333. Skofitsch G, Wimalawansa SJ, Jacobowitz DM, Gubisch W. Comparative immunohistochemical distribution of amylin-like and calcitonin gene related peptide like immunoreactivity in the rat central nervous system. Can J Physiol Pharmacol 73: 945–956,
1995.
334. Sletten K, Westermark P, Natvig JB. Characterization of amyloid fibril proteins from
medullary carcinoma of the thyroid. J Exp Med 143: 993–998, 1976.
315. Sakagashira S, Hiddinga HJ, Tateishi K, Sanke T, Hanabusa T, Nanjo K, Eberhardt NL.
S20G mutant amylin exhibits increased in vitro amyloidogenicity and increased intracellular cytotoxicity compared with wild-type amylin. Am J Pathol 157: 2101–2109,
2000.
335. Smeekens SP, Chan SJ, Steiner DF. The biosynthesis and processing of neuroendocrine peptides: identification of proprotein convertases involved in intravesicular processing. Prog Brain Res 92: 235–246, 1992.
316. Sakagashira S, Sanke T, Hanabusa T, Shimomura H, Ohagi S, Kumagaye KY, Nakajima
K, Nanjo K. Missense mutation of amylin gene (S20G) in Japanese NIDDM patients.
Diabetes 45: 1279 –1281, 1996.
336. Smeekens SP, Montag Ag Thomas G, Albiges-Rizo C, Carrol R, Benig M, Phillips LA,
Martin S, Ohagi S, Gardner P, Swift HH, Steiner DF. Proinsulin processing by the
subtilisin-related proprotein convertases furin, PC2, and PC3. Proc Natl Acad Sci USA
89: 8822– 8826, 1992.
317. Sandler S, Andersson A, Schnel lA, Mellgren A, Tollemar J, Borg H, Petersson B, Groth
CG, Hellerström C. Tissue culture of human fetal pancreas. Development and function of B-cells in vitro and transplantation of explants to nude mice. Diabetes 34:
1113–1119, 1985.
337. Smith PES, Brender JR, Ramamoorthy A. Induction of negative curvature as a mechanism of cell toxicity by amyloidogenic peptides: the case of islet amyloid polypeptide.
J Am Chem Soc 131: 4470 – 4478, 2009.
318. Sandler S, Stridsberg M. Chronic exposure of cultured rat pancreatic islets to elevated
concentrations of islet amyloid polypeptide (IAPP) causes a decrease in islet DNA
content and medium insulin accumulation. Regul Pept 53: 103–109, 1994.
319. Sanke T, Bell GI, Sample C, Rubenstein AH, Steiner DF. An islet amyloid peptide is
derived from an 89-amino acid precursor by proteolytic processing. J Biol Chem 263:
17243–17246, 1988.
320. Scherz-Shouval R, Elazar Z. ROS, mitochondria and the regulation of autophagy.
Trends Cell Biol 17: 422– 427, 2007.
321. Scheuner D, Kaufman RJ. The unfolded protein response: a pathway that links insulin
demand with beta-cell failure and diabetes. Endocr Rev 29: 317–333, 2008.
322. Schmitz A, Schneider A, Kummer MP, Herzog V. Endoplasmic reticulum-localized
amyloid beta-peptide is degraded in the cytosol by two distinct degradation pathways.
Traffic 5: 89 –101, 2004.
323. Schröder M. Endoplasmic reticulum stress responses. Cell Mol Life Sci 65: 862– 894,
2008.
324. Schwartz P. New patho-anatomic observations on amyloidosis in the aged. Fluorescence microscopic investigations. In: Amyloidosis, edited by Mandema E, Ruinen L,
Scholten JH, Cohen AS. Amsterdam: Excerpta Medica, 1968, p. 400 – 415.
325. Seino S. S20G mutation of the amylin gene is associated with Type II diabetes in
Japanese. Diabetologia 44: 906 –909, 2001.
326. Sellin D, Yan LM, Kapurniotu A, Winter R. Suppression of IAPP fibrillation at anionic
lipid membranes via IAPP-derived amyloid inhibitors and insulin. Biophys Chem 150:
73–79, 2010.
327. Serre-Beinier V, Bosco D, Zulianello L, Charollais A, Caille D, Charpantier E, Gauthier
BR, Diaferia GR, Giepmans BN, Lupi R, Marchetti P, Deng S, Buhler L, Berney T,
Cirulli V, Meda P. Cx36 makes channels coupling human pancreatic beta-cells, and
correlates with insulin expression. Hum Mol Genet 18: 428 – 439, 2009.
338. Smith RN, Kent SC, Nagle J, Selig M, Iafrate AJ, Najafian N, Hafler DA, Auchincloss H,
Orban T, Cagliero E. Pathology of an islet transplant 2 years after transplantation:
evidence for a nonimmunological loss. Transplantation 86: 54 – 62, 2008.
339. Soeller WC, Janson J, Hart SE, Parker JC, Carty MD, Stevenson RW, Kreutter DK,
Butler PC. Islet amyloid-associated diabetes in obese Avy/a mice expressing human
islet amyloid polypeptide. Diabetes 47: 743–750, 1998.
340. Song JL, Wang CC. Chaperone-like activity of protein disulfide-isomerase in the refolding of rhodanese. Eur J Biochem 231: 312–316, 1995.
341. Song SH, Kjems L, Ritzel R, McIntyre SM, Johnson ML, Veldhuis JD, Butler PC.
Pulsatile insulin secretion by human pancreatic islets. J Clin Endocrinol Metab 87:
213–221, 2002.
342. Soong R, Brender JR, Macdonald PM, Ramamoorthy A. Association of highly compact
type II diabetes related islet amyloid polypeptide intermediate species at physiological
temperature revealed by diffusion NMR spectroscopy. J Am Chem Soc 131: 7079 –
7085, 2009.
343. Spear GS, Caple MV, Sutherland LR. The pancreas in the degu. Exp Mol Pathol 40:
295–310, 1984.
344. Sriburi R, Jackowski S, Mori K, Brewer JW. XBP1: a link between the unfolded protein
response, lipid biosynthesis, and biogenesis of the endoplasmic reticulum. J Cell Biol
167: 35– 41, 2004.
345. Steiner DF. The proinsulin C-peptide: a multirole model. Exp Diab Res 5: 7–14, 2004.
346. Stridsberg M, Tjälve H, Wilander E. Whole-body autoradiography of 123I-labelled islet
amyloid polypeptide (IAPP). Accumulation in the lung parenchyma and in the villi of
the intestinal mucosa in rats. Acta Oncol 32: 155–159, 1993.
347. Störkel S, Schneider HM, Müntefering H, Kashiwagi S. Iatrogenic, insulin-dependent,
local amyloidosis. Lab Invest 48: 108 –111, 1983.
348. Suzuki K, Ohsumi Y. Molecular machinery of autophagosome formation in yeast,
Saccharomyces cerevisiae. FEBS Lett 581: 2156 –2161, 2007.
823
313. Ryan EA, Paty BW, Senior PA, Bigam D, Alfadhli E, Kneteman NM, Lakey JRT, Shapiro
AMJ. Five-year follow up after clinical islet transplantation. Diabetes 54: 2060 –2069,
2005.
328. Sexton PM, Paxinos G, Kenney MA, Wookey PJ, Beaumont K. In vitro autoradiographic localization of amylin binding sites in rat brain. Neuroscience 62: 553–567,
1994.
WESTERMARK ET AL.
349. Swift SM, Clayton HA, London NJ, James RF. The potential contribution of rejection
to survival of transplanted human islets. Cell Transplant 7: 599 – 606, 1998.
350. Tanida I, Mizushima N, Kiyooka M, Ohsumi M, Ueno T, Ohsumi Y, Kominami E.
Apg7p/Cvt2p: a novel protein-activating enzyme essential for autophagy. Mol Biol Cell
10: 1367–1379, 1999.
351. Taniguchi CM, Emanuelli B, Kahn CR. Critical nodes in signalling pathways: insights
into insulin action. Nat Rev Mol Cell Biol 7: 85–96, 2006.
352. Tatarek-Nossol M, Yan LM, Schmauder A, Tenidis K, Westermark G, Kapurniotu A.
Inhibition of hIAPP amyloid-fibril formation and apoptotic cell death by a designed
hIAPP amyloid core-containing hexapeptide. Chem Biol 12: 797– 809, 2005.
353. Tengholm A, Gylfe E. Oscillatory control of insulin secretion. Mol Cell Endocrinol 297:
58 –72, 2009.
355. Tomic JL, Pensalfini A, Head E, Glabe CG. Soluble fibrillar oligomer levels are elevated
in Alzheimer’s disease brain and correlate with cognitive dysfunction. Neurobiol Dis
35: 352–358, 2009.
356. Tomoda T, Kim JH, Zhan C, Hatten ME. Role of Unc51.1 and its binding partners in
CNS axon outgrowth. Genes Dev 18: 541–558, 2004.
357. Toshimori H, Narita R, Nakazato M, Asai J, Mitsukawa T, Kangawa K, Matsuo H,
Matsukura S. Islet amyloid polypeptide (IAPP) in the gastrointestinal tract and pancreas of man and rat. Cell Tissue Res 262: 401– 406, 1990.
358. Tyrberg B, Andersson A, Borg LA. Species differences in susceptibility of transplanted
and cultured pancreatic islets to the beta-cell toxin alloxan. Gen Comp Endocrinol 122:
238 –251, 2001.
359. Tyrberg B, Eizirik DL, Hellerström C, Pipeleers DG, Andersson A. Human pancreatic
beta-cell deoxyribonucleic acid-synthesis in islet grafts decreases with increasing organ donor age but increases in response to glucose stimulation in vitro. Endocrinology
137: 5694 –5699, 1996.
360. Tyrberg B, Eizirik DL, Marklund SL, Olejnicka B, Madsen OD, Andersson A. Human
islets in mixed islet grafts protect mouse pancreatic beta-cells from alloxan toxicity.
Pharmacol Toxicol 85: 269 –275, 1999.
361. Tyrberg B, Ustinov J, Otonkoski T, Andersson A. Stimulated endocrine cell proliferation and differentiation in transplanted human pancreatic islets: effects of the ob gene
and compensatory growth of the implantation organ. Diabetes 50: 301–307, 2001.
362. Udayasankar J, Kodama K, Hull RL, Zraika S, Aston-Mourney K, Subramanian SL,
Tong J, Faulenbach MV, Vidal J, Kahn SE. Amyloid formation results in recurrence of
hyperglycaemia following transplantation of human IAPP transgenic mouse islets.
Diabetologia 52: 145–153, 2009.
363. Ueda T, Ugawa S, Saishin Y, Shimada S. Expression of receptor-activity modifying
protein (RAMP) mRNAs in the mouse brain. Mol Brain Res 931: 36 – 45, 2001.
364. Urano F, Wang X, Bertolotti A, Zhang Y, Chung P, Harding HP, Ron D. Coupling of
stress in the ER to activation of JNK protein kinases by transmembrane protein kinase
IRE1. Science 287: 664 – 666, 2000.
365. Van der Vaart A, Mari M, Reggiori F. A picky eater: exploring the mechanisms of
selective autophagy in human pathologies. Traffic 9: 281–289, 2008.
366. Vantyghem MC, Kerr-Conte J, Arnalsteen L, Sergent G, Defrance F, Gmyr V, Declerck N, Raverdy V, Vandewalle B, Pigny P, Noel C, Pattou F. Primary graft function,
metabolic control, and graft survival after islet transplantation. Diabetes Care 32:
1473–1478, 2009.
367. Verchere CB, D’Alessio DA, Palmiter RD, Weir GC, Bonner-Weir S, Baskin DG, Kahn
SE. Islet amyloid formation associated with hyperglycemia in transgenic mice with
pancreatic beta cell expression of human islet amyloid polypeptide. Proc Natl Acad Sci
USA 93: 3492–3496, 1996.
371. Wang J, Xu J, Finnerty J, Furuta M, Steiner DF, Verchere CB. The prohormone
convertase enzyme 2 (PC2) is essential for processing pro-islet amyloid polypeptide at
the NH2-terminal cleavage site. Diabetes 50: 534 –539, 2001.
372. Wang XZ, Harding HP, Zhang Y, Jolicoeur EM, Kuroda M, Ron D. Cloning of mammalian Ire1 reveals diversity in the ER stress responses. EMBO J 17: 5708 –5717, 1998.
373. Wang ZL, Bennet WM, Ghatei MA, Byfield PG, Smith DM, Bloom SR. Influence of islet
amyloid polypeptide and the 8 –37 fragment of islet amyloid polypeptide on insulin
release from perifused rat islets. Diabetes 42: 330 –335, 1993.
374. Ward WK, LaCava EC, Paquette TL, Beard JC, Wallum BJ, Porte DJ. Disproportionate
elevation of immunoreactive proinsulin in type 2 (non-insulin-dependent) diabetes
mellitus and in experimental insulin resistance. Diabetologia 30: 698 –702, 1987.
375. Watada H, Kajimoto Y, Kaneto H, Matsuoka T, Fujitani Y, Miyazaki J, Yamasaki Y.
Involvement of the homeodomain-containing transcription factor PDX-1 in islet amyloid polypeptide gene transcription. Biochem Biophys Res Commun 746 –751, 1996.
376. Waters S, Marchbank K, Solomon E, Whitehouse C, MG. Interactions with LC3 and
polyubiquitin chains link nbr1 to autophagic protein turnover. FEBS Lett 583: 1846 –
1852, 2009.
377. Weichselbaum A, Stangl E. Zur Kenntnis der feineren Veränderungen des Pankreas
bei Diabetes mellitus. Wien klin Wochenshr 14: 968 –972, 1901.
378. Westermark G, Benig Arora M, Fox N, Carroll R, Chan SJ, Westermark P, Steiner DF.
Amyloid formation in response to b cell stress occurs in vitro, but not in vivo, in islets
of transgenic mice expressing human islet amyloid polypeptide. Mol Med 1: 542–553,
1995.
379. Westermark GT. Endocrine amyloid. In: Amyloid Proteins. The Beta Sheet Conformation
and Disease, edited by Sipe JD. Weinheim, Germany: Wiley-VCH, 2005, p. 723–754.
380. Westermark GT, Christmanson L, Terenghi G, Permert J, Betsholtz C, Larsson J,
Polak JM, Westermark P. Islet amyloid polypeptide: demonstration of mRNA in human pancreatic islets by in situ hybridization in islets with and without amyloid deposits. Diabetologia 36: 323–328, 1993.
381. Westermark GT, Falkmer S, Steiner DF, Chan SJ, Engström U, Westermark P. Islet
amyloid polypeptide is expressed in the pancreatic islet parenchyma of the teleostean
fish, Myoxocephalus (Cottus) scorpius. Comp Biochem Physiol B Comp Biochem 133:
119 –125, 2002.
382. Westermark GT, Gebre-Medhin S, Steiner DF, Westermark P. Islet amyloid development in a mouse strain lacking endogenous islet amyloid polypeptide (IAPP) but
expressing human IAPP. Mol Med 6: 998 –1007, 2000.
383. Westermark GT, Leckström A, Zhi M, Westermark P. Increased release of IAPP in
response to long-term high fat intake in mice. Horm Metab Res 30: 256 –258, 1998.
384. Westermark GT, Steiner DF, Gebre-Medhin S, Engström U, Westermark P. Pro islet
amyloid polypeptide (proIAPP) immunoreactivity in amyloid formation in the islets of
Langerhans. Upsala J Med Sci 105: 97–106, 2000.
385. Westermark GT, Westermark P, Berne C, Korsgren O. Widespread amyloid deposition in transplanted human pancreatic islets. N Engl J Med 359: 977–979, 2008.
386. Westermark GT, Westermark P, Eizirik D, Hellerström C, Fox N, Steiner DF, Andersson A. Differences in amyloid deposition in islets of transgenic mice expressing
human islet amyloid polypeptide versus human islets implanted into nude mice. Metabolism 48: 448 – 454, 1999.
387. Westermark GT, Westermark P, Nordin A, Törnelius E, Andersson A. Formation of
amyloid in human pancreatic islets transplanted to the liver and spleen of nude mice.
Upsala J Med Sci 108: 193–204, 2003.
388. Westermark P. Amyloid of human islets of Langerhans. I. Isolation and some characteristics. Acta Pathol Microbiol Scand 83: 439 – 446, 1975.
368. Wahren J, Ekberg K, Jörnvall H. C-peptide is a bioactive peptide. Diabetologia 50:
503–509, 2007.
389. Westermark P. Amyloid of human islets of Langerhans. II. Electron microscopic analysis of isolated amyloid. Virchows Arch 373: 161–166, 1977.
369. Wakabayashi M, Matsuzaki K. Ganglioside-induced amyloid formation by human islet
amyloid polypeptide in lipid rafts. FEBS Lett 583: 2854 –2858, 2009.
390. Westermark P. Aspects on human amyloid forms and their fibril polypeptides. FEBS
Lett 272: 5942–5949, 2005.
824
354. Tilakaratne N, Christopoulos G, Zumpe ET, Foord SM, Sexton PM. Amylin receptor
phenotypes derived from human calcitonin receptor/RAMP coexpression exhibit
pharmacological differences dependent on receptor isoform and host cell environment. J Pharmacol Exp Ther 294: 61–72, 2000.
370. Wang F, Adrian TE, Westermark GT, Ding X, Gasslander T, Permert J. Islet amyloid
polypeptide tonally inhibits beta-, alpha-, and delta-cell secretion in isolated rat pancreatic islets. Am J Physiol Endocrinol Metab 276: E19 –E24, 1999.
391. Westermark P. Fine structure of islets of Langerhans in insular amyloidosis. Virchows
Arch A 359: 1–18, 1973.
392. Westermark P. Islet amyloid polypeptide and amyloid in the islets of Langerhans. In:
Diabetes: Clinical Science in Practice, edited by Leslie RDG, Robbins D. Cambridge,
UK: Cambridge Univ. Press, 1995, p. 189 –199.
393. Westermark P. Mast cells in the islets of Langerhans in insular amyloidosis. Virchows
Arch Pathol Anat 354: 17–23, 1971.
394. Westermark P. Quantitative studies of amyloid in the islets of Langerhans. Upsala J
Med Sci 77: 91–94, 1972.
413. Wiltzius JJW, Sievers SA, Sawaya MR, Eisenberg D. Atomic structures of IAPP (amylin)
fusions suggest a mechanism for fibrillation and the role of insulin in the process.
Protein Sci 18: 1521–1530, 2009.
414. Wimalawansa SJ. Amylin, calcitonin gene-related peptide, calcitonin, and adrenomedullin: a paptide superfamily. Crit Rev Neurobiol 11: 167–239, 1997.
415. Woerle HJ, Albrecht M, Linke R, Zschau S, Neumann C, Nicolaus M, Gerich JE, Göke
B, Schirra J. Impaired hyperglycemia-induced delay in gastric emptying in patients with
type 1 diabetes deficient for islet amyloid polypeptide. Diabetes Care 31: 2325–2331,
2008.
416. Wojtusciszyn A, Armanet M, Morel P, Berney T, Bosco D. Insulin secretion from
human beta cells is heterogeneous and dependent on cell-to-cell contacts. Diabetologia 51: 1843–1852, 2008.
396. Westermark P, Benson MD, Buxbaum JN, Cohen AS, Frangione B, Ikeda SI, Masters
CL, Merlini G, Saraiva MJ, Sipe JD. A primer of amyloid nomenclature. Amyloid 14:
179 –183, 2007.
417. Wookey PJ, Cao Z, Cooper ME. Interaction of the renal amylin and renin-angiotensin
systems in animal models of diabetes and hypertension. Miner Electrolyte Metab 24:
389 –399, 1998.
397. Westermark P, Eizirik DL, Pipeleers DG, Hellerström C, Andersson A. Rapid deposition of amyloid in human islets transplanted into nude mice. Diabetologia 38: 543–
549, 1995.
418. Wookey PJ, Tikellis C, Du HC, Qin HF, Sexton PM, Cooper ME. Amylin binding in rat
renal cortex, stimulation of adenylyl cyclase, and activation of plasma renin. Am J
Physiol Renal Fluid Electrolyte Physiol 270: F289 –F294, 1996.
398. Westermark P, Engström U, Johnson KH, Westermark GT, Betsholtz C. Islet amyloid
polypeptide: pinpointing amino acid residues linked to amyloid fibril formation. Proc
Natl Acad Sci USA 87: 5036 –5040, 1990.
419. Xu W, Jiang P, Mu Y. Conformation preorganization: effects of S20G mutation on the
structure of human islet amyloid polypeptide segment. J Phys Chem B 113: 7308 –
7314, 2009.
399. Westermark P, Grimelius L. The pancreatic islet cells in insular amyloidosis in human
diabetic and non-diabetic adults. Acta Pathol Microbiol Scand 81: 291–300, 1973.
420. Yagui K, Kanatsuka A, Makino H. Construction of transgenic mouse system expressing
human islet amyloid polypeptide (IAPP)/amylin. Nippon Rinsho 52: 2746 –2750, 1994.
400. Westermark P, Grimelius L, Polak JM, Larsson LI, van Noorden S, Wilander E, Pearse
AGE. Amyloid in polypeptide hormone-producing tumors. Lab Invest 37: 212–215,
1977.
421. Yagui K, Yamaguchi T, Kanatsuka A, Shimada F, Huang CI, Tokuyama Y, Ohsawa H,
Yamamura K, Miyazaki J, Mikata A, Yoshida S, Makino H. Formation of islet amyloid
fibrils in beta-secretory granules of transgenic mice expressing human islet amyloid
polypeptide/amylin. Eur J Endocrinol 132: 487– 496, 1995.
401. Westermark P, Johnson KH, O’Brien TD, Betsholtz C. Islet amyloid polypeptide: a
novel controversy in diabetes research. Diabetologia 35: 297–303, 1992.
402. Westermark P, Li ZC, Westermark GT, Leckström A, Steiner DF. Effects of beta cell
granule components on human islet amyloid polypeptide fibril formation. FEBS Lett
379: 203–206, 1996.
403. Westermark P, Wernstedt C, O’Brien TD, Hayden DW, Johnson KH. Islet amyloid in
type 2 human diabetes mellitus and adult diabetic cats contains a novel putative
polypeptide hormone. Am J Pathol 127: 414 – 417, 1987.
404. Westermark P, Wernstedt C, Wilander E, Hayden DW, O’Brien TD, Johnson KH.
Amyloid fibrils in human insulinoma and islets of Langerhans of the diabetic cat are
derived from a neuropeptide-like protein also present in normal islet cells. Proc Natl
Acad Sci USA 84: 3881–3885, 1987.
405. Westermark P, Wernstedt C, Wilander E, Sletten K. A novel peptide in the calcitonin
gene related peptide family as an amyloid fibril protein in the endocrine pancreas.
Biochem Biophys Res Commun 140: 827– 831, 1986.
406. Westermark P, Wilander E. The influence of amyloid deposits on the islet volume in
maturity onset diabetes mellitus. Diabetologia 15: 417– 421, 1978.
407. Westermark P, Wilander E, Westermark GT, Johnson KH. Islet amyloid polypeptidelike immunoreactivity in the islet B cells of Type 2 (non-insulin-dependent) diabetic
and nondiabetic individuals. Diabetologia 30: 887– 892, 1987.
408. Wickbom J, Herrington MK, Permert J, Jansson A, Arnelo U. Gastric emptying in
response to IAPP and CCK in rats with subdiaphragmatic afferent vagotomy. Regul
Pept 148: 21–25, 2008.
409. Wilkinson KD, Tashayev VL, O’Connor LB, Larsen CN, Kasperek E, Pickart C. Metabolism of the polyubiquitin degradation signal: structure, mechanism, and role of
isopeptidase T. Biochemistry 34: 14535–14546, 1995.
410. Willcox ARS, Bone AJ, Foulis AK, Morgan NG. Analysis of islet inflammation in human
type 1 diabetes. Clin Exp Immunol 155: 173–181, 2009.
411. Williamson JA, Miranker AD. Direct detection of transient a-helical states in islet
amyloid polypeptide. Protein Sci 16: 110 –117, 2007.
412. Wiltzius JJ, Sievers SA, Sawaya MR, Cascio D, Popov D, Riekel C, Eisenberg D. Atomic
structure of the cross-beta spine of islet amyloid polypeptide (amylin). Protein Sci 17:
1467–1474, 2008.
422. Yamada K, Yuan X, Ishiyama S, Nonaka K. Glucose tolerance in Japanese subjects with
S20G mutation of the amylin gene. Diabetologia 41: 125–126, 1998.
423. Yamamoto K, Sato T, Matsui T, Sato M, Okada T, Yoshida H, Harada A, Mori K.
Transcriptional induction of mammalian ER quality control proteins is mediated by
single or combined action of ATF6alpha and XBP1. Dev Cell 13: 365–376, 2007.
424. Yankner BA, Dawes LR, Fisher S, Villa-Komaroff L, Oster-Granite ML, Neve RL.
Neurotoxicity of a fragment of the amyloid precursor associated with Alzheimer’s
disease. Science 245: 417– 420, 1989.
425. Yankner BA, Duffy LK, Kirschner DA. Neurotrophic and neurotoxic effects of amyloid
␤ protein: reversal by tachykinin neuropeptides. Science 250: 279 –282, 1990.
426. Yasojima K, McGeer EG, McGeer PL. Relationship between beta amyloid peptide
generating molecules and neprilysin in Alzheimer disease and normal brain. Brain Res
919: 115–121, 2001.
427. Yorimitsu T, Klionsky DJ. Eating the endoplasmic reticulum: quality control by autophagy. Trends Cell Biol 17: 279 –285, 2007.
428. Yorimitsu T, Klionsky DJ. Endoplasmic reticulum stress: a new pathway to induce
autophagy. Autophagy 3: 160 –162, 2007.
429. Yorimitsu T, Nair U, Yang Z, Klionsky DJ. Endoplasmic reticulum stress triggers
autophagy. J Biol Chem 281: 30299 –30304, 2006.
430. Yoshida H, Matsui T, Yamamoto A, Okada T, Mori K. XBP1 mRNA is induced by
ATF6 and spliced by IRE1 in response to ER stress to produce a highly active transcription factor. Cell 107: 881– 891, 2001.
431. Yoshida H, Okada T, Haze K, Yanagi H, Yura T, Negishi M, Mori K. ATF6 activated by
proteolysis binds in the presence of NF-Y (CBF) directly to the cis-acting element
responsible for the mammalian unfolded protein response. Mol Cell Biol 20: 6755–
6767, 2000.
432. Young A. Historical background. Adv Pharmacol 52: 1–18, 2005.
433. Young A. Inhibition of gastric emptying. Adv Pharmacol 52: 99 –121, 2005.
434. Young A. Inhibition of glucagon secretion. Adv Pharmacol 52: 151–171, 2005.
435. Young A. Receptor pharmacology. Adv Pharmacol 52: 47– 65, 2005.
825
395. Westermark P, Andersson A, Westermark GT. Is aggregated IAPP a cause of beta-cell
failure in transplanted human pancreatic islets? Curr Diab Rep 5: 184 –188, 2005.
WESTERMARK ET AL.
436. Yumlu S, Barany R, Eriksson M, Röcken C. Localized insulin-derived amyloidosis in
patients with diabetes mellitus: a case report. Hum Pathol 40: 1655–1660, 2009.
437. Zaidi M, Datta HK, Bevis PJ, Wimalawansa SJ, MacIntyre I. Amylin-amide: a new
bone-conserving peptide from the pancreas. Exp Physiol 75: 529 –536, 1990.
438. Zethelius B, Berglund L, Hänni A, Berne C. The interaction between impaired acute
insulin response and insulin resistance predicts type 2 diabetes and impairment of
fasting glucose. Upsala J Med Sci 113: 117–130, 2008.
439. Zhang Y, Ranta F, Tang C, Shumilina E, Mahmud H, Föller M, Ullrich S, Häring HU,
Lang F. Sphingomyelinase dependent apoptosis following treatment of pancreatic
beta-cells with amyloid peptides Abeta(1– 42) or IAPP. Apoptosis 14: 878 – 889, 2009.
440. Zhao HL, Lai FM, Tong PC, Zhong DR, Yang D, Tomlinson B, Chan JC. Prevalence
and clinicopathological characteristics of islet amyloid in chinese patients with type 2
diabetes. Diabetes 52: 2759 –2766, 2003.
442. Zhu T, Wang Y, He B, Zang J, He Q, Zhang W. Islet amyloid polypeptide acts on
glucose-stimulated beta cells to reduce voltage-gated calcium channel activation, intracellular Ca2⫹ concentration, and insulin secretion. Diabetes Metab Res Rev. In
press.
826
444. Zierath JR, Galuska D, Engström Å, Johnson KH, Betsholtz C, Westermark P, Wallberg-Henriksson H. Human islet amyloid polypeptide at pharmacological levels inhibits insulin and phorbol ester-stimulated glucose transport in in vitro incubated human
muscle strips. Diabetologia 35: 26 –31, 1992.
445. Zraika S, Aston-Mourney K, Marek P, Hull RL, Green PS, Udayasankar J, Subramanian
SL, Raleigh DP, Kahn SE. Neprilysin impedes islet amyloid formation by inhibition of
fibril formation rather than peptide degradation. J Biol Chem 285: 18177–18183, 2010.
446. Zraika S, Hull RL, Udayasankar J, Aston-Mourney K, Subramanian SL, Kisilevsky R,
Szarek WA, Kahn SE. Oxidative stress is induced by islet amyloid formation and
time-dependently mediates amyloid-induced beta cell apoptosis. Diabetologia 52:
626 – 635, 2009.
447. Zraika S, Hull RL, Udayasankar J, Clark A, Utzschneider KM, Tong J, Gerchman F,
Kahn SE. Identification of the amyloid-degrading enzyme neprilysin in mouse islets and
potential role in islet amyloidogenesis. Diabetes 56: 304 –310, 2007.
448. Zraika S, Hull RL, Verchere CB, Clark A, Potter KJ, Fraser PE, Raleigh DP, Kahn SE.
Toxic oligomers and islet beta cell death: guilty by association or convicted by circumstantial evidence? Diabetologia 53: 1046 –1056, 2010.
441. Zheng X, Ren W, Zhang S, Liu J, Li S, Li J, Yang P, He J, Su S, Li P. Serum levels of
proamylin and amylin in normal subjects and patients with impaired glucose regulation
and type 2 diabetes mellitus. Acta Diabetol 47: 265–270, 2010.
443. Zhu X, Rouille Y, Lamango NS, Steiner DF, Lindberg I. Internal cleavage of the
inhibitory 7B2 carboxyl-terminal peptide by PC2: a potential mechanism for its inactivation. Proc Natl Acad Sci USA 93: 4919 – 4924, 1996.

islet amyloid polypeptide, islet amyloid, and diabetes mellitus

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