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The Protein Journal Feb 2020Control of amylin agglomeration is of interest for both the study of pathophysiology and the design of amylin-based pharmaceutical products. Here we report the effects...
Control of amylin agglomeration is of interest for both the study of pathophysiology and the design of amylin-based pharmaceutical products. Here we report the effects of a large set of common buffering agents, aminoacids and nucleoside phosphates over the amylin amyloid aggregation. Circular dichroism showed no apparent effects of the co-solutes over the secondary-structure of soluble amylin. Instead, we found a large dependence of the fibrillation process on the total amount of co-solute charged groups. The amyloid nature of the aggregates was confirmed by transmission electron microscopy, X-ray diffraction and infrared spectroscopy. While acidic pH and low-ionic co-solutes shows the largest size effect in hampering aggregation, no further effect was observed that could identify a single compound as a major direct heterotropic determinants of the amyloid process. These data suggest a more physico-chemical effect of co-solutes over the modulation of amylin instead of a chemical entity-related causal factor.
Topics: Amyloid; Buffers; Circular Dichroism; Diabetes Mellitus; Humans; Hydrogen-Ion Concentration; Islet Amyloid Polypeptide; Microscopy, Electron, Transmission; Protein Aggregation, Pathological; Protein Structure, Secondary; Spectrophotometry, Infrared; X-Ray Diffraction
PubMed: 31808036
DOI: 10.1007/s10930-019-09877-w -
Scientific Reports Jul 2019Recent evidence supports involvement of amylin and the amylin receptor in the pathogenesis of Alzheimer's disease (AD). We have previously shown that amylin receptor...
Recent evidence supports involvement of amylin and the amylin receptor in the pathogenesis of Alzheimer's disease (AD). We have previously shown that amylin receptor antagonist, AC253, improves spatial memory in AD mouse models. Herein, we generated and screened a peptide library and identified two short sequence amylin peptides (12-14 aa) that are proteolytically stable, brain penetrant when administered intraperitoneally, neuroprotective against Aβ toxicity and restore diminished levels of hippocampal long term potentiation in AD mice. Systemic administration of the peptides for five weeks in aged 5XFAD mice improved spatial memory, reduced amyloid plaque burden, and neuroinflammation. The common residue SQELHRLQTY within the peptides is an essential sequence for preservation of the beneficial effects of the fragments that we report here and constitutes a new pharmacological target. These findings suggest that the amylin receptor antagonism may represent a novel therapy for AD.
Topics: Alzheimer Disease; Animals; Female; Hippocampus; Islet Amyloid Polypeptide; Long-Term Potentiation; Male; Mice; Mice, Inbred C57BL; Neuroprotective Agents; Peptide Fragments; Receptors, Islet Amyloid Polypeptide; Spatial Memory
PubMed: 31358858
DOI: 10.1038/s41598-019-47255-9 -
FASEB Journal : Official Publication of... Jan 2012Amylin, a 37-aa pancreatic peptide, was found to be expressed in the preoptic area of mother rats in our recent microarray study. Here, we report a marked increase in...
Amylin, a 37-aa pancreatic peptide, was found to be expressed in the preoptic area of mother rats in our recent microarray study. Here, we report a marked increase in amylin expression around parturition and show that amylin mRNA level remains elevated as long as the pups are not removed from the dams. Amylin expression is also induced in maternally behaving (sensitized) nonlactating but not in nonsensitized nulliparous females or in females that did not become maternal despite the sensitization procedure. Immunohistochemistry verified the increased amylin peptide expression in maternally behaving rats and demonstrated the same expression pattern of amylin as in situ hybridization histochemistry. Ovariectomy had no effect on the activation of amylin neurons, suggesting sexual steroid-independent mechanisms. In subsequent functional experiments, mothers were separated from their pups for 22 h. On return of the pups, neuronal activation was found in the mother's preoptic area, with a distribution pattern similar to amylin-expressing neurons. Subsequent double labeling revealed that 86-93% of amylin neurons were activated by pup exposure. The results implicate amylin in the control of maternal adaptations, possibly exerting its actions on maternal behaviors via amylin receptors present in brain regions to which preoptic neurons project.
Topics: Animals; Animals, Suckling; Behavior, Animal; Female; Islet Amyloid Polypeptide; Maternal Behavior; Maternal Deprivation; Neural Pathways; Neurons; Ovariectomy; Peripartum Period; Postpartum Period; Pregnancy; Preoptic Area; Proto-Oncogene Proteins c-fos; RNA, Messenger; Rats; Rats, Wistar
PubMed: 21965599
DOI: 10.1096/fj.11-191841 -
Redox Biology Sep 2023Diabetes mellitus currently affects ∼10% of the population worldwide, with Type 2 predominating, and this incidence is increasing steadily. Both Type 1 and 2 are...
Diabetes mellitus currently affects ∼10% of the population worldwide, with Type 2 predominating, and this incidence is increasing steadily. Both Type 1 and 2 are complex diseases, involving β-cell death and chronic inflammation, but the pathways involved are unresolved. Chronic inflammation is characterized by increased oxidant formation, with this inducing protein modification, altered function and immunogenicity. Amylin, a peptide hormone co-secreted with insulin by β-cells, has attracted considerable interest for its amyloidogenic properties, however, the effects that oxidants have on amylin aggregation and function are poorly understood. Amylin was exposed in vitro to hypochlorous acid, hydrogen peroxide and peroxynitrous acid/peroxynitrite to investigate the formation of post-translational oxidative modifications (oxPTMs, via mass spectrometry) and fibril formation (via transmission electron microscopy). Amylin free acid (AFA) was also examined to investigate the role of the C-terminal amide in amylin. Oxidant exposure led to changes in aggregate morphology and abundance of oxPTMs in a concentration-dependent manner. The toxicity and immunogenic potential of oxidant-modified amylin or AFA on pancreatic islet cells (INS-1E), human monocyte cell line (THP-1) and monocyte-derived dendritic cells (moDCs) were examined using metabolic activity and cytokine assays, and flow cytometry. No significant changes in vitality or viability were detected, but exposure to oxidant-modified amylin or AFA resulted in altered immunogenicity when compared to the native proteins. THP-1 and moDCs show altered expression of activation markers and changes in cytokine secretion. Furthermore, oxidant-treated amylin and AFA promoted maturation of THP-1 and pre-mature moDCs, as determined by changes in size, and maturation markers.
Topics: Humans; Islet Amyloid Polypeptide; Oxidants; Amyloid; Islets of Langerhans; Myeloid Cells; Cytokines
PubMed: 37544243
DOI: 10.1016/j.redox.2023.102835 -
Anatomia, Histologia, Embryologia Jul 2024In this study, we investigated amylin-like substance distribution in the pancreas of Japanese quail (Coturnix japonica) using a specific anti-rat amylin serum. We...
In this study, we investigated amylin-like substance distribution in the pancreas of Japanese quail (Coturnix japonica) using a specific anti-rat amylin serum. We detected amylin-immunoreactive cells dispersed in the pancreatic extra-islet region but not in the islet region. The synthetic rat amylin-containing serum pre-absorption abolished the staining profile. Almost all amylin-immunoreactive cells were immuno-positive for peptide YY (PYY). In addition, certain amylin-immunoreactive cells stained immuno-positive for glucagon. Amylin and PYY co-secreted from the extra-islet cells might participate in the insulin and glucagon release regulation in the pancreas and food intake modulation through the central nervous system.
Topics: Animals; Peptide YY; Islet Amyloid Polypeptide; Coturnix; Glucagon; Pancreas; Immunohistochemistry; Islets of Langerhans; Male; Rats
PubMed: 38864153
DOI: 10.1111/ahe.13074 -
JOP : Journal of the Pancreas Jul 2001Amyloid deposits within the islet of the pancreas have been known for a century. In 1987, the islet amyloid precursor polypeptide (IAPP) amylin (a 37 amino acid) was... (Review)
Review
Amyloid deposits within the islet of the pancreas have been known for a century. In 1987, the islet amyloid precursor polypeptide (IAPP) amylin (a 37 amino acid) was discovered. Recently there has been an explosion of amylin's importance in the development of type 2 diabetes mellitus (T2DM). This review is intended to share what is understood about amylin derived amyloid and the role it plays in T2DM. Whether islet amyloid is an epiphenomenona, a tombstone, or a trigger it leaves an indelible footprint in greater that 70% of the patients with T2DM. There is current data supporting the damaging role of intermediate sized toxic amyloid particles to the beta cell resulting in a beta cell defect which contributes to a relative deficiency or loss of insulin secretion. Within the islet there is an intense redox stress which may be associated with the unfolding of amylin's native secondary structure compounding its amyloidogenic properties. In addition to the beta cell defect there may be an absorptive defect as a result of amyloid deposition in the basement membranes which form an envelope around the inta-islet capillary endothelium. We have an opportunity to change our current treatment modalities with newer medications and we should attempt to diagnose T2DM earlier and use these newer treatment strategies in combination to decrease glucotoxicity without elevating endogenous insulin and amylin. In the 21st century our goal should be to prevent remodeling, save the pancreatic islet, conquer islet amyloid, and amyloid diabetes.
Topics: Amino Acid Sequence; Amyloid; Diabetes Mellitus, Type 2; Humans; Islet Amyloid Polypeptide; Molecular Sequence Data
PubMed: 11875249
DOI: No ID Found -
Neuropsychopharmacology : Official... Dec 2014Amylin is a peptide co-secreted with insulin that penetrates into the brain, and produces satiation-like effects via actions in the brainstem, hypothalamus, and...
Amylin is a peptide co-secreted with insulin that penetrates into the brain, and produces satiation-like effects via actions in the brainstem, hypothalamus, and mesencephalon. Little is known, however, about the effects of amylin in the nucleus accumbens shell (AcbSh), where a circumscribed zone of intense amylin receptor (AMY-R) binding overlaps reported mappings of a 'hotspot' for μ-opioid receptor (μ-OR) amplification of food reward. Here, the ability of intra-AcbSh AMY-R signaling to modulate μ-OR-driven feeding was explored. Amylin (1-30 ng) was administered with the μ-OR agonist, D-Ala2, N-MePhe4, Gly-ol]-enkephalin (DAMGO) (0.25 μg), directly into the AcbSh of ad libitum-maintained rats. Amylin dose-dependently reversed DAMGO-induced hyperphagia; 3 ng of amylin reduced DAMGO-mediated feeding by nearly 50%. This dose was, however, completely ineffective at altering DAMGO-induced feeding in the anterior dorsal striatum. Intra-AcbSh amylin alone (3-30 ng) modestly suppressed 10% sucrose intake in ad libitum-maintained rats, and chow in food-deprived rats, but only at the 30-ng dose. This result indicates that reversal of AcbSh DAMGO-induced feeding at a 10-fold lower dose was neither due to malaise nor motoric impairment. Finally, intra-AcbSh infusion of the AMY-R antagonist, AC187 (20 μg), significantly attenuated the ability of prefeeding to suppress DAMGO-induced food intake, with no effects in non-prefed rats. Hence, AMY-R signaling negatively modulates μ-OR-mediated appetitive responses at the level of the AcbSh. The results with AC187 indicate that endogenous AMY-R transmission in the AcbSh curtails opioid function in the postprandial period, suggesting a novel pathway for peripheral-central integration in the control of appetitive motivation and opioid reward.
Topics: Analgesics, Opioid; Analysis of Variance; Animals; Dose-Response Relationship, Drug; Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; Feeding Behavior; Food Preferences; Islet Amyloid Polypeptide; Male; Nucleus Accumbens; Peptide Fragments; Rats; Rats, Sprague-Dawley; Receptors, Islet Amyloid Polypeptide; Receptors, Opioid, mu; Signal Transduction
PubMed: 24957819
DOI: 10.1038/npp.2014.153 -
Annals of Neurology Oct 2013Hyperamylinemia, a common pancreatic disorder in obese and insulin-resistant patients, is known to cause amylin oligomerization and cytotoxicity in pancreatic islets,...
OBJECTIVE
Hyperamylinemia, a common pancreatic disorder in obese and insulin-resistant patients, is known to cause amylin oligomerization and cytotoxicity in pancreatic islets, leading to β-cell mass depletion and development of type 2 diabetes. Recent data has revealed that hyperamylinemia also affects the vascular system, heart, and kidneys. We therefore hypothesized that oligomerized amylin might accumulate in the cerebrovascular system and brain parenchyma of diabetic patients.
METHODS
Amylin accumulation in the brain of diabetic patients with vascular dementia or Alzheimer disease (AD), nondiabetic patients with AD, and age-matched healthy controls was assessed by quantitative real time polymerase chain reaction, immunohistochemistry, Western blot, and enzyme-linked immunosorbent assay.
RESULTS
Amylin oligomers and plaques were identified in the temporal lobe gray matter from diabetic patients, but not controls. In addition, extensive amylin deposition was found in blood vessels and perivascular spaces. Intriguingly, amylin deposition was also detected in blood vessels and brain parenchyma of patients with late onset AD without clinically apparent diabetes. Mixed amylin and amyloid β (Aβ) deposits were occasionally observed. However, amylin accumulation leads to amyloid formation independent of Aβ deposition. Tissues infiltrated by amylin showed increased interstitial space, vacuolation, spongiform change, and capillaries bent at amylin accumulation sites. Unlike the pancreas, there was no evidence of amylin synthesis in the brain.
INTERPRETATION
Metabolic disorders and aging promote accumulation of amylin amyloid in the cerebrovascular system and gray matter, altering microvasculature and tissue structure. Amylin amyloid formation in the wall of cerebral blood vessels may also induce failure of elimination of Aβ from the brain, thus contributing to the etiology of AD.
Topics: Aged; Aged, 80 and over; Alzheimer Disease; Amyloid beta-Peptides; Brain; Diabetic Angiopathies; Female; Humans; Islet Amyloid Polypeptide; Male; RNA, Messenger
PubMed: 23794448
DOI: 10.1002/ana.23956 -
Inorganic Chemistry Feb 2020Protein aggregation has attracted substantial interest because of its role in causing many serious illnesses, such as neurodegenerative diseases and type II diabetes....
Protein aggregation has attracted substantial interest because of its role in causing many serious illnesses, such as neurodegenerative diseases and type II diabetes. Recent studies have shown that protein aggregation can be prevented by forming metal ion complexes with a target protein, which affects their conformation in solution and their physical properties, such as aggregation. Thus, understanding the interactions between aggregating molecules and bioactive metal ions such as Cu is beneficial for new drug discovery. Pramlintide, a synthetic peptide drug, and its natural counterpart rat amylin are known to be resistant to aggregation because of the presence of proline residues, which are usually β-sheet "breakers" within their amino acid sequence. Here, we investigate the Cu coordination properties of pramlintide and rat amylin using nuclear magnetic resonance, circular dichroism, electron paramagnetic resonance, ultraviolet-visible spectroscopy, potentiometry, and mass spectrometry. We test the influence of Cu on the aggregation properties of these amylin analogues with thioflavin T assays. We find that both peptides form stable complexes with Cu with similar affinities at a 1:1 ratio. The N-termini of both peptides are involved in Cu binding; His18 imidazole is an equally attractive binding site in the case of pramlintide. Our results show that Cu ions influence the aggregation of pramlintide, but not that of rat amylin.
Topics: Amino Acid Sequence; Animals; Binding Sites; Coordination Complexes; Copper; Islet Amyloid Polypeptide; Protein Binding; Protein Multimerization; Rats
PubMed: 32027132
DOI: 10.1021/acs.inorgchem.9b03498 -
Scientific Reports Jun 2020Human pancreatic islet amyloid polypeptide (hIAPP) and beta amyloid (Aβ) can accumulate in Type 2 diabetes (T2D) and Alzheimer's disease (AD) brains and evidence...
Human pancreatic islet amyloid polypeptide (hIAPP) and beta amyloid (Aβ) can accumulate in Type 2 diabetes (T2D) and Alzheimer's disease (AD) brains and evidence suggests that interaction between the two amyloidogenic proteins can lead to the formation of heterocomplex aggregates. However, the structure and consequences of the formation of these complexes remains to be determined. The main objective of this study was to characterise the different types and morphology of Aβ-hIAPP heterocomplexes and determine if formation of such complexes exacerbate neurotoxicity. We demonstrate that hIAPP promotes Aβ oligomerization and formation of small oligomer and large aggregate heterocomplexes. Co-oligomerized Aβ42-hIAPP mixtures displayed distinct amorphous structures and a 3-fold increase in neuronal cell death as compared to Aβ and hIAPP alone. However, in contrast to hIAPP, non-amyloidogenic rat amylin (rIAPP) reduced oligomer Aβ-mediated neuronal cell death. rIAPP exhibited reductions in Aβ induced neuronal cell death that was independent of its ability to interact with Aβ and form heterocomplexes; suggesting mediation by other pathways. Our findings reveal distinct effects of IAPP peptides in modulating Aβ aggregation and toxicity and provide new insight into the potential pathogenic effects of Aβ-IAPP hetero-oligomerization and development of IAPP based therapies for AD and T2D.
Topics: Alzheimer Disease; Amyloid beta-Peptides; Animals; Brain; Cell Line, Tumor; Diabetes Mellitus, Type 2; Humans; Islet Amyloid Polypeptide; Microscopy, Electron, Transmission; Neurons; Nuclear Magnetic Resonance, Biomolecular; Pancreas; Peptide Fragments; Protein Aggregates; Protein Aggregation, Pathological; Protein Multimerization; Rats
PubMed: 32587390
DOI: 10.1038/s41598-020-66602-9