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Martínez-Navarro I, Díaz-Molina R, Pulido-Capiz A, Mas-Oliva J, Luna-Reyes I, Rodríguez-Velázquez E, Rivero IA, Ramos-Ibarra MA, Alatorre-Meda M, García-González V. Lipid Modulation in the Formation of β-Sheet Structures. Implications for De Novo Design of Human Islet Amyloid Polypeptide and the Impact on β-Cell Homeostasis. Biomolecules 2020; 10:biom10091201. [PMID: 32824918 PMCID: PMC7563882 DOI: 10.3390/biom10091201] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 08/03/2020] [Accepted: 08/04/2020] [Indexed: 12/25/2022] Open
Abstract
Human islet amyloid polypeptide (hIAPP) corresponds to a 37-residue hormone present in insulin granules that maintains a high propensity to form β-sheet structures during co-secretion with insulin. Previously, employing a biomimetic approach, we proposed a panel of optimized IAPP sequences with only one residue substitution that shows the capability to reduce amyloidogenesis. Taking into account that specific membrane lipids have been considered as a key factor in the induction of cytotoxicity, in this study, following the same design strategy, we characterize the effect of a series of lipids upon several polypeptide domains that show the highest aggregation propensity. The characterization of the C-native segment of hIAPP (residues F23-Y37), together with novel variants F23R and I26A allowed us to demonstrate an effect upon the formation of β-sheet structures. Our results suggest that zwitterionic phospholipids promote adsorption of the C-native segments at the lipid-interface and β-sheet formation with the exception of the F23R variant. Moreover, the presence of cholesterol did not modify this behavior, and the β-sheet structural transitions were not registered when the N-terminal domain of hIAPP (K1-S20) was characterized. Considering that insulin granules are enriched in phosphatidylserine (PS), the property of lipid vesicles containing negatively charged lipids was also evaluated. We found that these types of lipids promote β-sheet conformational transitions in both the C-native segment and the new variants. Furthermore, these PS/peptides arrangements are internalized in Langerhans islet β-cells, localized in the endoplasmic reticulum, and trigger critical pathways such as unfolded protein response (UPR), affecting insulin secretion. Since this phenomenon was associated with the presence of cytotoxicity on Langerhans islet β-cells, it can be concluded that the anionic lipid environment and degree of solvation are critical conditions for the stability of segments with the propensity to form β-sheet structures, a situation that will eventually affect the structural characteristics and stability of IAPP within insulin granules, thus modifying the insulin secretion.
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Affiliation(s)
- Israel Martínez-Navarro
- Departamento de Bioquímica, Facultad de Medicina Mexicali, Universidad Autónoma de Baja California, Mexicali 21000, Baja California, Mexico; (I.M.-N.); (R.D.-M.); (A.P.-C.)
| | - Raúl Díaz-Molina
- Departamento de Bioquímica, Facultad de Medicina Mexicali, Universidad Autónoma de Baja California, Mexicali 21000, Baja California, Mexico; (I.M.-N.); (R.D.-M.); (A.P.-C.)
| | - Angel Pulido-Capiz
- Departamento de Bioquímica, Facultad de Medicina Mexicali, Universidad Autónoma de Baja California, Mexicali 21000, Baja California, Mexico; (I.M.-N.); (R.D.-M.); (A.P.-C.)
- Laboratorio de Biología Molecular, Facultad de Medicina Mexicali, Universidad Autónoma de Baja California, Mexicali 21000, Baja California, Mexico
| | - Jaime Mas-Oliva
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Ciudad de Mexico 04510, Mexico; (J.M.-O.); (I.L.-R.)
| | - Ismael Luna-Reyes
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Ciudad de Mexico 04510, Mexico; (J.M.-O.); (I.L.-R.)
| | - Eustolia Rodríguez-Velázquez
- Facultad de Odontología, Universidad Autónoma de Baja California, Tijuana 22390, Mexico;
- Tecnológico Nacional de México/I.T. Tijuana, Centro de Graduados e Investigación en Química-Grupo de Biomateriales y Nanomedicina, Tijuana 22510, Mexico
| | - Ignacio A. Rivero
- Tecnológico Nacional de México/Instituto Tecnológico de Tijuana, Centro de Graduados e Investigación en Química, Tijuana 22510, Baja California, Mexico;
| | - Marco A. Ramos-Ibarra
- Facultad de Ciencias Químicas e Ingeniería, Universidad Autónoma de Baja California, Tijuana 22390, Baja California, Mexico;
| | - Manuel Alatorre-Meda
- Cátedras CONACyT- Tecnológico Nacional de México/I.T. Tijuana, Centro de Graduados e Investigación en Química-Grupo de Biomateriales y Nanomedicina, Tijuana 22510, Mexico;
| | - Victor García-González
- Departamento de Bioquímica, Facultad de Medicina Mexicali, Universidad Autónoma de Baja California, Mexicali 21000, Baja California, Mexico; (I.M.-N.); (R.D.-M.); (A.P.-C.)
- Correspondence: ; Tel.: +52-68-6557-1622
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Cervantes A, Waymouth EK, Petrov MS. African-Americans and Indigenous Peoples Have Increased Burden of Diseases of the Exocrine Pancreas: A Systematic Review and Meta-Analysis. Dig Dis Sci 2019; 64:249-261. [PMID: 30259278 DOI: 10.1007/s10620-018-5291-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Accepted: 09/14/2018] [Indexed: 12/12/2022]
Abstract
Ethnic health disparity is a well-acknowledged issue in many disease settings, but not diseases of the exocrine pancreas. A systematic review and meta-analysis was conducted to explore the race- and ethnicity-specific burden of diseases of the exocrine pancreas. Studies that compared health-related endpoints between two or more ethnicities were eligible for inclusion. Proportion meta-analyses were conducted to compare burden between groups. A total of 42 studies (24 on pancreatic cancer, 17 on pancreatitis, and one on pancreatic cyst) were included in the systematic review, of which 19 studies were suitable for meta-analyses. The incidence of pancreatic cancer was 1.4-fold higher among African-Americans, while the incidence of acute pancreatitis was 4.8-fold higher among an indigenous population (New Zealand Māori) compared with Caucasians. The prevalence of post-pancreatitis diabetes mellitus was up to 3.0-fold higher among certain ethnicities, including Asians, Pacific Islanders, and indigenous populations compared with Caucasians. The burden of diseases of the exocrine pancreas differs between ethnicities, with African-Americans and certain indigenous populations being at the greatest risk of developing these diseases. Development of race- and ethnicity-specific screening as well as protocols for lifestyle modifications may need to be considered with a view to reducing the disparities in burden of diseases of the exocrine pancreas.
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Affiliation(s)
- Aya Cervantes
- School of Medicine, University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand
| | - Ellen K Waymouth
- School of Medicine, University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand
| | - Maxim S Petrov
- School of Medicine, University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand.
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Merriman TR, Wilcox PL. Cardio-metabolic disease genetic risk factors among Māori and Pacific Island people in Aotearoa New Zealand: current state of knowledge and future directions. Ann Hum Biol 2018; 45:202-214. [PMID: 29877153 DOI: 10.1080/03014460.2018.1461929] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
CONTEXT Cardio-metabolic conditions in Aotearoa New Zealand (NZ) Māori and non-indigenous Polynesian (Pacific) populations have been increasing in prevalence and severity, especially over the last two decades. OBJECTIVES To assess knowledge on genetic and non-genetic risk factors for cardio-metabolic disease in the Māori and Pacific populations residing in Aotearoa NZ by a semi-systematic review of the PubMed database. To outline possible future directions in genetic epidemiological research with Māori and Pacific communities. RESULTS There have been few studies to confirm that risk factors in other populations also associate with cardio-metabolic conditions in Māori and Pacific populations. Such data are important when interventions are considered. Genetic studies have been sporadic, with no genome-wide association studies done. CONCLUSIONS Biomedical research with Māori and Pacific communities is important to reduce the prevalence and impact of the cardio-metabolic diseases, as precision medicine is implemented in other Aotearoa NZ populations using overseas findings. Genuine engagement with Māori and Pacific communities is needed to ensure positive outcomes for genetic studies, from data collection through to analysis and dissemination. Important is building trust, understanding by researchers of fundamental cultural concepts and implementing protocols that minimise risks and maximise benefits. Approaches that utilise information such as genealogical information and whole genome sequencing technologies will provide new insights into cardio-metabolic conditions-and new interventions for affected individuals and families.
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Affiliation(s)
- Tony R Merriman
- a Biochemistry Department , University of Otago , Dunedin , Aotearoa , New Zealand
| | - Phillip L Wilcox
- b Department of Mathematics and Statistics , University of Otago , Dunedin , Aotearoa , New Zealand
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IAPP in type II diabetes: Basic research on structure, molecular interactions, and disease mechanisms suggests potential intervention strategies. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018. [DOI: 10.1016/j.bbamem.2018.02.020] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Pulido-Capiz A, Díaz-Molina R, Martínez-Navarro I, Guevara-Olaya LA, Casanueva-Pérez E, Mas-Oliva J, Rivero IA, García-González V. Modulation of Amyloidogenesis Controlled by the C-Terminal Domain of Islet Amyloid Polypeptide Shows New Functions on Hepatocyte Cholesterol Metabolism. Front Endocrinol (Lausanne) 2018; 9:331. [PMID: 29988450 PMCID: PMC6026639 DOI: 10.3389/fendo.2018.00331] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 05/31/2018] [Indexed: 12/30/2022] Open
Abstract
The islet amyloid polypeptide (IAPP) or amylin maintains a key role in metabolism. This 37-residues-peptide could form pancreatic amyloids, which are a characteristic feature of diabetes mellitus type 2. However, some species do not form amyloid fibril structures. By employing a biomimetic approach, we generated an extensive panel of optimized sequences of IAPP, which could drastically reduce aggregation propensity. A structural and cellular characterization analysis was performed on the C-terminal domain with the highest aggregation propensity. This allowed the observation of an aggregative phenomenon dependent of the lipid environment. Evaluation of the new F23R variant demonstrated inhibition of β-sheet structure and, therefore, amyloid formation on the native C-terminal, phenomenon that was associated with functional optimization in calcium and cholesterol management coupled with the optimization of insulin secretion by beta cells. When F23R variant was evaluated in microglia cells, a model of amyloidosis, cytotoxic conditions were not registered. In addition, it was found that C-terminal sequences of IAPP could modulate cholesterol metabolism in hepatocytes through regulation of SREBP-2, apoA-1, ABCA1, and LDLR, mechanism that may represent a new function of IAPP on the metabolism of cholesterol, increasing the LDL endocytosis in hepatocytes. Optimized sequences with only one residue modification in the C-terminal core aggregation could diminish β-sheet formation and represent a novel strategy adaptable to other pharmacological targets. Our data suggest a new IAPP function associated with rearrangements on metabolism of cholesterol in hepatocytes.
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Affiliation(s)
- Angel Pulido-Capiz
- Departamento de Bioquímica, Facultad de Medicina Mexicali, Universidad Autónoma de Baja California, Mexicali, Mexico
| | - Raúl Díaz-Molina
- Departamento de Bioquímica, Facultad de Medicina Mexicali, Universidad Autónoma de Baja California, Mexicali, Mexico
| | - Israel Martínez-Navarro
- Departamento de Bioquímica, Facultad de Medicina Mexicali, Universidad Autónoma de Baja California, Mexicali, Mexico
- Facultad de Enfermería, Universidad Autónoma de Baja California, Mexico City, Mexico
| | - Lizbeth A. Guevara-Olaya
- Departamento de Bioquímica, Facultad de Medicina Mexicali, Universidad Autónoma de Baja California, Mexicali, Mexico
| | - Enrique Casanueva-Pérez
- Departamento de Bioquímica, Facultad de Medicina Mexicali, Universidad Autónoma de Baja California, Mexicali, Mexico
| | - Jaime Mas-Oliva
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
| | - Ignacio A. Rivero
- Centro de Graduados e Investigación en Química, Instituto Tecnológico de Tijuana, Tijuana, Mexico
| | - Victor García-González
- Departamento de Bioquímica, Facultad de Medicina Mexicali, Universidad Autónoma de Baja California, Mexicali, Mexico
- *Correspondence: Victor García-González,
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Smaoui MR, Waldispühl J. Complete characterization of the mutation landscape reveals the effect on amylin stability and amyloidogenicity. Proteins 2015; 83:1014-26. [PMID: 25809921 DOI: 10.1002/prot.24795] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2014] [Revised: 03/08/2015] [Accepted: 03/10/2015] [Indexed: 12/25/2022]
Abstract
Type-II diabetes is believed to be partially aggravated by the emergence of toxic amylin protein deposits in the extracellular space of the pancreas β-cells. Amylin, the regulatory hormone that is co-secreted with insulin, has been observed to misfold into toxic structures. Pramlintide, an FDA approved injectable amylin analog mutated at positions 25, 28, and 29 was therefore developed to create a more stable, soluble, less-aggregating, and equipotent peptide that is used as an adjunctive therapy for diabetes. However, because Pramlintide is not ideal, researchers have been exploring other amylin analogs as therapeutic replacements. In this work, we assist the finding of optimal analogs by computationally revealing the mutational landscape of amylin. We computed the structure energies of all possible single-point mutations and studied the effect they have on amylin stability and amyloidogenicity. Each of the 37 amylin residues was mutated in silico into the 19 canonical amino acids and an energy function computing the Lennard-Jones, Coulomb and solvation energy was used to analyze changes in stability. The mutation landscape identified amylin's conserved stable regions, residues that can be tweaked to further stabilize structure, regions that are susceptible to mutations, and mutations that are amyloidogenic. We used the single-point mutational landscape data to generate estimations for higher-order multiple-point mutational landscapes and discovered millions of three-point mutations that are more stable and less amyloidogenic than Pramlintide. The landscapes provided an explanation for the effect of the S20G and Q10R mutations on the onset of diabetes of the Chinese and Maori populations, respectively.
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Affiliation(s)
- Mohamed Raef Smaoui
- School of Computer Science, McGill University, Montreal, Quebec, Canada.,McGill Center for Bioinformatics, McGill University, Montreal, Quebec, Canada
| | - Jérôme Waldispühl
- School of Computer Science, McGill University, Montreal, Quebec, Canada.,McGill Center for Bioinformatics, McGill University, Montreal, Quebec, Canada
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Poppitt SD, Silvestre MP, Liu A. Etiology of Obesity Over the Life Span: Ecologic and Genetic Highlights from New Zealand Cohorts. Curr Obes Rep 2014; 3:38-45. [PMID: 26626466 DOI: 10.1007/s13679-013-0079-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The origins of the New Zealand population are highly diverse. New Zealand Māori are the indigenous peoples with a population of approximately half a million (~12 %), with the remainder comprising predominantly European/Caucasian (~50 %), Pacific Island Polynesian (~28 %) and Asian (~10 %) peoples. With a prevalence of overweight and obesity of 65 % for adults >15 years of age, of which 28 % have a BMI > 30 kg/m(2), New Zealand has been ranked third highest in a global OECD obesity review, behind only the US and Mexico. Levels of childhood obesity are also significant, with 31 % of New Zealand's children either overweight or obese. Few gender differences exist, but there are significant differences between ethnicities (Asian > European Caucasian > Māori > Pacific) with disproportionate representation by those poorer and with less formal education. A high 62 % of Pacifika are obese and virtually the entire adult population has a BMI >25 kg/m(2). Public health measures to limit progressive increases in weight are unsuccessful, and clearly should be priority for government focused on disease prevention.
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Affiliation(s)
- S D Poppitt
- Human Nutrition Unit, University of Auckland, 18 Carrick Place, Mt Eden, Auckland, 1024, New Zealand.
- School of Biological Sciences, University of Auckland, Auckland, New Zealand.
- Department of Medicine, University of Auckland, Auckland, New Zealand.
- Riddet Institute, Palmerston North, New Zealand.
| | - M P Silvestre
- Human Nutrition Unit, University of Auckland, 18 Carrick Place, Mt Eden, Auckland, 1024, New Zealand
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - A Liu
- Human Nutrition Unit, University of Auckland, 18 Carrick Place, Mt Eden, Auckland, 1024, New Zealand
- Department of Medicine, University of Auckland, Auckland, New Zealand
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Histopathological correlations of islet amyloidosis with apolipoprotein E polymorphisms in type 2 diabetic Chinese patients. Pancreas 2013; 42:1129-37. [PMID: 24005233 DOI: 10.1097/mpa.0b013e3182965e6e] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
OBJECTIVE Islet amyloidosis and arteriosclerosis are histopathological hallmarks in type 2 diabetes. Apolipoprotein E (ApoE) is a common component of amyloidosis. ApoE [Latin Small Letter Open E]4 allele is associated with arteriosclerosis and cerebral amyloidosis in Alzheimer disease. We examined the correlations of ApoE polymorphisms with islet amyloidosis in type 2 diabetes. METHODS Genomic DNA samples were obtained from 117 autopsy cases with type 2 diabetes and 209 nondiabetic cases. ApoE genotypes and amylin gene mutations were determined by polymerase chain reaction-ligase detection reaction analysis. Islet amyloidosis and arteriosclerosis were evaluated by staining of thioflavin T, amylin, ApoE, and amyloid P component. RESULTS In the diabetic group, 33.3% in group [Latin Small Letter Open E]2 ([Latin Small Letter Open E]2[Latin Small Letter Open E]2, [Latin Small Letter Open E]2[Latin Small Letter Open E]3), 23.6% in group [Latin Small Letter Open E]3 ([Latin Small Letter Open E]3[Latin Small Letter Open E]3), and 62.5% in group [Latin Small Letter Open E]4 ([Latin Small Letter Open E]4[Latin Small Letter Open E]4, [Latin Small Letter Open E]3[Latin Small Letter Open E]4) had islet amyloidosis. After adjustment for confounders, group [Latin Small Letter Open E]4 had an odds ratio of 7.0 (95% confidence interval, 1.3-38.0; P = 0.023) in having islet amyloidosis compared to group [Latin Small Letter Open E]3. Diabetic cases with islet amyloidosis had more severe arteriosclerosis (P = 0.0111), arteriolar hyalinosis (P = 0.0369), and interstitial fibrosis (P = 0.0188) than those without amyloidosis. Immunoreactivity of both ApoE and amyloid P component was detected in islet amyloid deposits and arteriosclerotic lesions. CONCLUSIONS In type 2 diabetes, islet amyloidosis and arteriosclerosis share common pathophysiological features with ApoE [Latin Small Letter Open E]4 as a probable linking factor.
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Ahmad E, Ahmad A, Singh S, Arshad M, Khan AH, Khan RH. A mechanistic approach for islet amyloid polypeptide aggregation to develop anti-amyloidogenic agents for type-2 diabetes. Biochimie 2011; 93:793-805. [DOI: 10.1016/j.biochi.2010.12.012] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2010] [Accepted: 12/19/2010] [Indexed: 10/18/2022]
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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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Novials A, Rodriguez-Mañas L, Chico A, El Assar M, Casas S, Gomis R. Amylin and hypertension: association of an amylin -G132A gene mutation and hypertension in humans and amylin-induced endothelium dysfunction in rats. J Clin Endocrinol Metab 2007; 92:1446-50. [PMID: 17213278 DOI: 10.1210/jc.2006-1980] [Citation(s) in RCA: 7] [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
CONTEXT Amylin has been linked to the development of hypertension in several pathological states related to hypertension and insulin resistance, although there is scant data regarding its potential mechanisms of action. The -132 G/A mutation located within an activator domain of the amylin gene's promoter was first identified in a small cohort of Spanish patients with type 2 diabetes. OBJECTIVE The objective of the study was to test the interference of amylin peptide with endothelium-dependent responses as an added potential mechanism for amylin-induced hypertension. DESIGN A total of 384 patients with type 2 diabetes and 207 healthy controls were subjected to clinical analysis and genetic screening for the -132 G/A mutation of the amylin gene. The effect of amylin on endothelium-dependent responses was analyzed in aortic rings and mesenteric microvessels from nondiabetic rats. RESULTS The prevalence of the mutation was 10.1 vs. 0.9% in the control population (P<0.001). Hypertension was higher in a diabetic population carrying the mutation than in diabetic noncarriers (74 vs. 57%; P<0.05). Diabetic carriers showed higher fasting amylin levels than diabetic noncarriers (11.4+/-7 vs. 8.2+/-3 pmol/liter; P<0.05). Preincubation with 20 pmol/liter amylin impaired the relaxant responses induced by acetylcholine in rat aorta and mesenteric microvessels. This effect was abolished in both vascular beds in the presence of 100 micromol/liter NG-nitro-L-arginine methyl ester. CONCLUSIONS We propose that amylin levels and hypertension may be linked by a novel mechanism involving the capacity of amylin to induce endothelial dysfunction by interfering with nitric oxide-mediated responses.
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Affiliation(s)
- Anna Novials
- Institute of Diabetes, Sardà Farriol Foundation, Passeig Bonanova 69, 6th floor, 08017 Barcelona, Spain.
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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 Mol Basis Dis 2005; 1740:74-8. [PMID: 15878744 DOI: 10.1016/j.bbadis.2005.02.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2004] [Revised: 01/10/2005] [Accepted: 02/01/2005] [Indexed: 11/26/2022]
Abstract
The over-expression of the islet amyloid polypeptide (IAPP) gene could be a causal factor for islet amyloidosis and beta-cell destruction in Type 2 diabetes (T2DM). An IAPP gene promoter polymorphism, IAPP-132G to A, has been associated with T2DM in Spain. To investigate this polymorphism in other cohorts and in relation to therapy, DNA from 425 T2DM and 279 unrelated, non-diabetic UK subjects (ND) and 102 T2DM and 80 ND Finnish subjects was examined. The relationship of amyloid severity (percent amyloid/islet) to prevalence (number of islets affected) and the association of IAPP-132G/A with amyloid was determined in post-mortem pancreas from 38 T2DM subjects. The -132G/A was not associated with T2DM in the UK cohorts (4.5% T2DM; 3.2% ND) or associated with requirement for insulin therapy by 6 years. The mutation was and undetected in the Finnish samples but a new variant, -166T/C, was identified in 2 Finnish T2DM subjects. -132G/A was found in 2/38 diabetic, amyloid-containing and 3/19 ND, amyloid-free subjects. The islet amyloid severity was linearly correlated with the prevalence in T2DM. The IAPP-132G/A promoter polymorphism is not associated with T2DM, a requirement for insulin therapy or with the degree of islet amyloidosis in cohorts from the UK or Finland.
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Affiliation(s)
- Christopher Esapa
- Diabetes Research Laboratories, Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, Oxford, OX3 7LJ, UK
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Shepherd LMA, Campbell SC, Macfarlane WM. Transcriptional regulation of the IAPP gene in pancreatic beta-cells. ACTA ACUST UNITED AC 2005; 1681:28-37. [PMID: 15566941 DOI: 10.1016/j.bbaexp.2004.09.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2004] [Revised: 07/09/2004] [Accepted: 09/27/2004] [Indexed: 11/19/2022]
Abstract
Islet amyloid polypeptide (IAPP or amylin) is co-secreted with insulin from the pancreatic beta-cells. Transcription of the IAPP gene is controlled by a complex promoter region, spanning from -2798 to +450 relative to the transcriptional start site. In the present study, we have used reporter gene analysis and semi-quantitative RT-PCR to establish that insulin, glucagon, glucagon-like peptide-1 (GLP-1) and the GLP-1 derivatives GLP(7-36)Amide and Exendin-4 all stimulate IAPP promoter activity, as well as endogenous IAPP mRNA levels in isolated islets of Langerhans. In contrast, somatostatin had no effect, and whilst the inflammatory cytokines TNF-alpha, IL-1alpha and IL-1beta had no effect on promoter activity, they all decreased IAPP mRNA levels in isolated islets. Finally, utilising a series of deletion reporter gene constructs of the human IAPP gene promoter, we used overexpression studies to establish that HNF-3beta (FoxA2) negatively regulates the IAPP promoter, whilst the MODY3 transcription factor HNF-1alpha positively regulates promoter activity.
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Affiliation(s)
- Louisa M A Shepherd
- School of Cell and Molecular Biosciences, University of Newcastle upon Tyne, The Medical School, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
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Novials A, Mato E, Lucas M, Franco C, Rivas M, Santisteban P, Gomis R. Mutation at position -132 in the islet amyloid polypeptide ( IAPP) gene promoter enhances basal transcriptional activity through a new CRE-like binding site. Diabetologia 2004; 47:1167-1174. [PMID: 15243700 DOI: 10.1007/s00125-004-1439-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2003] [Accepted: 04/17/2004] [Indexed: 12/30/2022]
Abstract
AIMS/HYPOTHESIS Mutations in the islet amyloid polypeptide ( IAPP) gene may play a potential role in the abnormal regulation or expression of the peptide. The aim of this study was to determine the functional role of the -132 G/A mutation reported in the promoter region of the IAPP gene in a population of Spanish Type 2 diabetic patients. METHODS We investigated the transcriptional activity using MIN6 cells and luciferase reporter plasmids in several culture conditions. Key regulatory elements of the IAPP promoter region were also analysed by electrophoretic mobility shift assays (EMSA). RESULTS The mutant construct doubled IAPP transcriptional activity ( p<0.001). Both constructs showed severely reduced promoter activity (four-fold decrease) in the presence of verapamil and diazoxide. In contrast, IAPP promoter activity was doubled after incubation with forskolin or dexamethasone, regardless of the glucose concentrations in the culture media. EMSA revealed that the -132 G/A mutation increased the binding affinity through two DNA-protein complexes. In addition, a cAMP-responsive element binding protein (CREB) was identified by super-shift EMSA. CONCLUSIONS/INTERPRETATION Our studies show that the wild-type and the mutant constructs are regulated in a similar pattern under all conditions, strongly indicating that the -132 G/A mutation increases basal but not inducible transcription. These results may be explained by new binding to the mutant region through CREB and other transcription factors not yet identified.
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Affiliation(s)
- A Novials
- Diabetes Institute Sarda Farriol Foundation, Barcelona, Spain
| | - E Mato
- Diabetes Institute Sarda Farriol Foundation, Barcelona, Spain
- Endocrinology and Diabetes Unit, Department of Medicine, Hospital Clinic, Biomedical Research Institute August Pi Sunyer (IDIBAPS), University of Barcelona, Villarroel 170, 08036, Barcelona, Spain
| | - M Lucas
- Diabetes Institute Sarda Farriol Foundation, Barcelona, Spain
- Endocrinology and Diabetes Unit, Department of Medicine, Hospital Clinic, Biomedical Research Institute August Pi Sunyer (IDIBAPS), University of Barcelona, Villarroel 170, 08036, Barcelona, Spain
| | - C Franco
- Endocrinology and Diabetes Unit, Department of Medicine, Hospital Clinic, Biomedical Research Institute August Pi Sunyer (IDIBAPS), University of Barcelona, Villarroel 170, 08036, Barcelona, Spain
| | - M Rivas
- Biomedical Research Institute Alberto Sols (CSIC), Autonomous University of Madrid, Madrid, Spain
| | - P Santisteban
- Biomedical Research Institute Alberto Sols (CSIC), Autonomous University of Madrid, Madrid, Spain
| | - R Gomis
- Endocrinology and Diabetes Unit, Department of Medicine, Hospital Clinic, Biomedical Research Institute August Pi Sunyer (IDIBAPS), University of Barcelona, Villarroel 170, 08036, Barcelona, Spain.
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