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Zhang XX, Pan YH, Huang YM, Zhao HL. Neuroendocrine hormone amylin in diabetes. World J Diabetes 2016; 7:189-97. [PMID: 27162583 PMCID: PMC4856891 DOI: 10.4239/wjd.v7.i9.189] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Revised: 03/16/2016] [Accepted: 04/05/2016] [Indexed: 02/05/2023] Open
Abstract
The neuroendocrine hormone amylin, also known as islet amyloid polypeptide, is co-localized, co-packaged and co-secreted with insulin from adult pancreatic islet β cells to maintain glucose homeostasis. Specifically, amylin reduces secretion of nutrient-stimulated glucagon, regulates blood pressure with an effect on renin-angiotensin system, and delays gastric emptying. The physiological actions of human amylin attribute to the conformational α-helix monomers whereas the misfolding instable oligomers may be detrimental to the islet β cells and further transform to β-sheet fibrils as amyloid deposits. No direct evidence proves that the amylin fibrils in amyloid deposits cause diabetes. Here we also have performed a systematic review of human amylin gene changes and reported the S20G mutation is minor in the development of diabetes. In addition to the metabolic effects, human amylin may modulate autoimmunity and innate inflammation through regulatory T cells to impact on both human type 1 and type 2 diabetes.
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Apoptosis induced by islet amyloid polypeptide soluble oligomers is neutralized by diabetes-associated specific antibodies. Sci Rep 2014; 4:4267. [PMID: 24589570 PMCID: PMC3940978 DOI: 10.1038/srep04267] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Accepted: 02/05/2014] [Indexed: 11/24/2022] Open
Abstract
Soluble oligomeric assemblies of amyloidal proteins appear to act as major pathological agents in several degenerative disorders. Isolation and characterization of these oligomers is a pivotal step towards determination of their pathological relevance. Here we describe the isolation of Type 2 diabetes-associated islet amyloid polypeptide soluble cytotoxic oligomers; these oligomers induced apoptosis in cultured pancreatic cells, permeated model lipid vesicles and interacted with cell membranes following complete internalization. Moreover, antibodies which specifically recognized these assemblies, but not monomers or amyloid fibrils, were exclusively identified in diabetic patients and were shown to neutralize the apoptotic effect induced by these oligomers. Our findings support the notion that human IAPP peptide can form highly toxic oligomers. The presence of antibodies identified in the serum of diabetic patients confirms the pathological relevance of the oligomers. In addition, the newly identified structural epitopes may also provide new mechanistic insights and a molecular target for future therapy.
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Abstract
Gut microbiota is an assortment of microorganisms inhabiting the length and width of the mammalian gastrointestinal tract. The composition of this microbial community is host specific, evolving throughout an individual's lifetime and susceptible to both exogenous and endogenous modifications. Recent renewed interest in the structure and function of this "organ" has illuminated its central position in health and disease. The microbiota is intimately involved in numerous aspects of normal host physiology, from nutritional status to behavior and stress response. Additionally, they can be a central or a contributing cause of many diseases, affecting both near and far organ systems. The overall balance in the composition of the gut microbial community, as well as the presence or absence of key species capable of effecting specific responses, is important in ensuring homeostasis or lack thereof at the intestinal mucosa and beyond. The mechanisms through which microbiota exerts its beneficial or detrimental influences remain largely undefined, but include elaboration of signaling molecules and recognition of bacterial epitopes by both intestinal epithelial and mucosal immune cells. The advances in modeling and analysis of gut microbiota will further our knowledge of their role in health and disease, allowing customization of existing and future therapeutic and prophylactic modalities.
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Affiliation(s)
- Inna Sekirov
- Michael Smith Laboratories, Department of Microbiology and Immunology, The University of British Columbia, Vancouver, British Columbia, Canada
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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 2009; 113:7308-14. [DOI: 10.1021/jp8106827] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Weixin Xu
- School of Biological Sciences, Nanyang Technological University, Singapore 637551
| | - Ping Jiang
- School of Biological Sciences, Nanyang Technological University, Singapore 637551
| | - Yuguang Mu
- School of Biological Sciences, Nanyang Technological University, Singapore 637551
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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. Diabetes Res Clin Pract 2003; 60:125-9. [PMID: 12706321 DOI: 10.1016/s0168-8227(03)00019-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Islet amyloid deposition, which is mainly composed of amylin, is a characteristic pathological finding in patients with type 2 diabetes mellitus. A missense mutation in amylin at amino acid 20 from Serine to Glycine (S20G) has been shown to be associated with type 2 diabetes. In this study, the frequency and clinical characteristics of the S20G mutation in Korean was examined with 364 unrelated type 2 diabetic and 151 non-diabetic subjects. The S20G mutation was found in seven out of 364 diabetic patients (1.92%) and in three out of 151 non-diabetic subjects (1.99%). The body mass index (BMI) of the patients with the S20G mutation was lower than those with the wild type (21.2+/-1.8 vs. 24.3+/-3.0 kg/m(2); P<0.01). The prediabetic maximum BMI was also lower in patients with the S20G mutation (22.4+/-2.3 vs. 26.4+/-3.2 kg/m(2); P<0.01). Patients with the S20G mutation had a higher HbA(1c) level than those with the wild type (9.3+/-1.4 vs. 7.7+/-1.3%; P<0.01). In summary, the frequency of the S20G mutation in the amylin gene is 1.92% in unrelated Korean type 2 diabetic patients and this mutation is associated with a lower BMI and a higher HbA(1c) level.
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Affiliation(s)
- Young Min Cho
- Department of Internal Medicine, Seoul National University College of Medicine, 28 Yongon-Dong, Chongno-Gu, South Korea
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Rojas I, Gomis R, Casals E, Quintó LI, Franco C, Novials A. Polymorphism in intron 2 of islet amyloid polypeptide gene is associated with lower low-density lipoprotein cholesterol in nondiabetic subjects and in type 2 diabetic patients. Endocrine 2002; 19:185-9. [PMID: 12588049 DOI: 10.1385/endo:19:2:185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The aim of this study was to investigate the presence of mutations in the islet amyloid polypeptide (IAPP) gene in a Spanish population with type 2 diabetes and gestational diabetes mellitus (GDM). Using polymerase chain reaction single-stranded conformation polymorphism, we examined the coding region and the 5'-untranslated region (UTR) of the IAPP gene in 177 unrelated type 2 diabetic patients, 110 healthy control subjects, 38 women with GDM, and 38 gestational control subjects. Mutations were confirmed by DNA sequencing. A heterozygous C-to-A nucleotide substitution at +79 bp in intron 2 of the IAPP gene was detected. The frequencies of the +79-bp polymorphism (A allele) were 6.8% in type 2 diabetic patients, 7.7% in nondiabetic control subjects, 11.8% in women with GDM, and 9.2% in gestational control subjects. No AA genotypes were detected. Nondiabetic subjects and patients with type 2 diabetes bearing the CA genotype had lower low-density lipoprotein (LDL) cholesterol levels than subjects bearing wild genotype. Multivariate logistic regression analysis showed an independent association (p < 0.001; odds ratio: 0.33; 95% confidence interval: 0.17-0.63). We did not detect any sequence variant within exons 1 or 2. One diabetic patient was heterozygous for a silent mutation at codon 31 of exon 3 (Asn31 AAC --> AAT). Our findings indicate that the presence of the +79-bp polymorphism of the IAPP gene in nondiabetic subjects and in patients with type 2 diabetes is associated with lower levels of LDL cholesterol. Furthermore, abnormalities of the coding regions or the 5'-UTR of the IAPP gene are not associated with type 2 diabetes or GDM in the Spanish population.
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Affiliation(s)
- I Rojas
- Diabetes Institute, Fundació Sardà Farriol, Barcelona, Spain
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Lee SC, Hashim Y, Li JK, Ko GT, Critchley JA, Cockram CS, Chan JC. The islet amyloid polypeptide (amylin) gene S20G mutation in Chinese subjects: evidence for associations with type 2 diabetes and cholesterol levels. Clin Endocrinol (Oxf) 2001; 54:541-6. [PMID: 11318791 DOI: 10.1046/j.1365-2265.2001.01244.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND AND OBJECTIVES There has been evidence that the S20G mutation in the islet amyloid polypeptide (amylin) gene may be associated with type 2 diabetes. In the present study, we investigated the distribution of the mutation in Hong Kong Chinese, and examined whether there was evidence for associations between the mutation and type 2 diabetes and/or metabolic profiles. SUBJECTS AND METHODS This study involved 227 early and 235 late-onset (defined as onset age < or = 40 and > 40 years, respectively) type 2 diabetic patients, as well as 126 nondiabetic subjects. The mutation was detected using a PCR-RFLP method. RESULTS We identified six (2.6%) and one (0.4%) patients heterozygous for the mutation from the early and late-onset groups, respectively (P = 0.05). None of the nondiabetic subjects had the mutation. Insulin deficiency and poor glycaemic control were not common findings amongst carriers of the mutation. In the early onset group, the patients with the mutation had lower plasma levels of total (4.3 +/- 0.9 mmol/l vs. 5.3 +/- 1.1 mmol/l, P = 0.02) and low density lipoprotein (LDL)-cholesterol (2.3 +/- 0.7 mmol/l vs. 3.2 +/- 0.9 mmol/l, P = 0.01) than those without the mutation. CONCLUSIONS Our data suggest that the islet amyloid polypeptide gene mutation might be associated with early occurrence of type 2 diabetes and lower plasma levels of total and low density lipoprotein-cholesterol in the Chinese population.
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Affiliation(s)
- S C Lee
- Department of Medicine and Therapeutics, The Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China.
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Ng MC, Lee SC, Ko GT, Li JK, So WY, Hashim Y, Barnett AH, Mackay IR, Critchley JA, Cockram CS, Chan JC. Familial early-onset type 2 diabetes in Chinese patients: obesity and genetics have more significant roles than autoimmunity. Diabetes Care 2001; 24:663-71. [PMID: 11315828 DOI: 10.2337/diacare.24.4.663] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE We examined the prevalence of different forms of diabetes in Hong Kong Chinese patients with familial early-onset type 2 diabetes and compared their clinical features with patients with familial late-onset type 2 diabetes. RESEARCH DESIGN AND METHODS A total of 145 young patients with early-onset diabetes (age and age at diagnosis < or = 40 years) and a family history of diabetes were studied. They were screened for mutations in the genes encoding glucokinase, hepatocyte nuclear factor (HNF)-4alpha, and HNF-1alpha. The mitochondrial DNA A-->G at nucleotide 3243 (mt3243) and amyLin S20G mutations were studied, and antibodies to GAD (anti-GADs) were also examined. RESULTS The prevalence of putative diabetogenic gene mutations and autoimmune markers were 4% for glucokinase, 0% for HNF-4alpha, 5% for HNF-1alpha, 3% for mt3243, 2% for amylin 520G, and 4% for anti-GAD. Compared with late-onset patients, the patients with early-onset diabetes had a higher prevalence of a parental history of diabetes and were generally more obese. When classified by obesity indexes (BMI and waist circumference), the obese patients, especially those with early-onset diabetes, had a clustering of cardiovascular risk factors and increased rates of retinopathy and albuminuria. CONCLUSIONS; Genetic factors (up to 14%) and obesity (55%) play more significant roles than autoimmunity (4%) in familial type 2 diabetes in young Chinese patients. The significance of obesity-related genes and other gene-gene and gene-environment interactions in these young patients remains to be determined.
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Affiliation(s)
- M C Ng
- Department of Medicine and Therapeutics, Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, SAR.
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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 to wild-type amylin. THE AMERICAN JOURNAL OF PATHOLOGY 2000; 157:2101-9. [PMID: 11106582 PMCID: PMC1885776 DOI: 10.1016/s0002-9440(10)64848-1] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Human amylin, a major constituent of pancreatic amyloid deposits, may be a pathogenetic factor for noninsulin-dependent diabetes mellitus (NIDDM). We demonstrated that the human amylin S20G gene mutation (S20G) was associated with a history of early onset, more severe type of NIDDM, linking the amylin gene to this disease. Also, we demonstrated that expression of human wild-type (WT) amylin in COS-1 cells leads to intracellular amyloidogenesis and induction of apoptosis, suggesting a possible mechanism for disease induction. Therefore we compared the abilities of S20G and WT amylin to induce apoptosis in transfected COS-1 cells and form amyloid in vitro. We transfected the rat (RAT), mutated human (MUT), WT, and S20G amylin genes into COS-1 cells and measured apoptosis using fluorescent-activated cell sorting analysis at 48, 72, and 96 hours. At 96 hours apoptosis increased significantly (P < 0.01) in cells transfected with WT and S20G over RAT or MUT (WT, 19%; S20G, 25%; RAT, 13%; and MUT, 12%) and the difference between WT and S20G was significant (P < 0.05). Synthetic WT and S20G monomeric peptides were used to generate amyloid fibrils in vitro as measured by the thioflavin T binding assay. The S20G amylin formed approximately twofold more amyloid at a rate approximately threefold higher than WT. Electron micrography indicated that the in vitro amyloid generated by WT and S20G amylins were morphologically indistinguishable. The results suggest that increased cytotoxicity by S20G is because of increased amyloidogenicity, which may be a causative factor in the early development of NIDDM, possibly through loss of ss cell mass.
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Affiliation(s)
- S Sakagashira
- Departments of Medicine, Biochemistry and Molecular Biology, and Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, USA
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Affiliation(s)
- J W Höppener
- Department of Internal Medicine, University Medical Center, Utrecht, The Netherlands.
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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. Diabetes Res Clin Pract 2000; 49:195-7. [PMID: 10963832 DOI: 10.1016/s0168-8227(00)00142-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- T Hayakawa
- First Department of Internal Medicine, School of Medicine, Kanazawa University, 13-1 Takara-machi, Kanazawa, 920-8641, Ishikawa, Japan
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Hart LM, Stolk RP, Dekker JM, Nijpels G, Grobbee DE, Heine RJ, Maassen JA. Prevalence of variants in candidate genes for type 2 diabetes mellitus in The Netherlands: the Rotterdam study and the Hoorn study. J Clin Endocrinol Metab 1999; 84:1002-6. [PMID: 10084586 DOI: 10.1210/jcem.84.3.5563] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We have analyzed the association of variants in the genes for amylin, insulin receptor, insulin receptor substrate-1 (IRS-1), and coagulation factor V with type 2 diabetes mellitus. Random samples of subjects with type 2 diabetes and controls were taken from two population-based studies, the Hoorn and Rotterdam studies, to reduce the risk of artifactual associations. No association was found for variants in the genes for amylin, IRS-1, and coagulation factor V, nor was there any evidence for epistatic interactions between these gene variants. A significant difference in the frequency of the Arg972 allele of the IRS-1 gene was observed between control subjects from Hoorn and Rotterdam (9.4% vs. 18.6%; P < 0.05). The insulin receptor Met985 variant was found at frequencies of 4.4% and 1.8%, respectively, in type 2 diabetic (n = 433) and normoglycemic patients (n = 799; P < 0.02). Inclusion of data from two other studies yielded a summarized odds ratio of 1.87 (95% confidence interval, 1.06-3.29; P = 0.03). We conclude that the association between the Met985 variant in the insulin receptor gene and type 2 diabetes, which we previously reported in the Rotterdam study, is supported by thejoint analysis with a second population-based study and other studies. The large regional differences in allele frequency of the Arg972 allele of IRS-1 gene makes genetic association studies of this gene less reliable.
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Affiliation(s)
- L M Hart
- Department of Molecular Cell Biology, Leiden University Medical Center, The Netherlands
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