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Ramzy A, Kieffer TJ. Altered islet prohormone processing: A cause or consequence of diabetes? Physiol Rev 2021; 102:155-208. [PMID: 34280055 DOI: 10.1152/physrev.00008.2021] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Peptide hormones are first produced as larger precursor prohormones that require endoproteolytic cleavage to liberate the mature hormones. A structurally conserved but functionally distinct family of nine prohormone convertase enzymes (PCs) are responsible for cleavage of protein precursors of which PC1/3 and PC2 are known to be exclusive to neuroendocrine cells and responsible for prohormone cleavage. Differential expression of PCs within tissues define prohormone processing; whereas glucagon is the major product liberated from proglucagon via PC2 in pancreatic α-cells, proglucagon is preferentially processed by PC1/3 in intestinal L cells to produce glucagon-like peptides 1 and 2 (GLP-1, GLP-2). Beyond our understanding of processing of islet prohormones in healthy islets, there is convincing evidence that proinsulin, proIAPP, and proglucagon processing is altered during prediabetes and diabetes. There is predictive value of elevated circulating proinsulin or proinsulin : C-peptide ratio for progression to type 2 diabetes and elevated proinsulin or proinsulin : C-peptide is predictive for development of type 1 diabetes in at risk groups. After onset of diabetes, patients have elevated circulating proinsulin and proIAPP and proinsulin may be an autoantigen in type 1 diabetes. Further, preclinical studies reveal that α-cells have altered proglucagon processing during diabetes leading to increased GLP-1 production. We conclude that despite strong associative data, current evidence is inconclusive on the potential causal role of impaired prohormone processing in diabetes, and suggest that future work should focus on resolving the question of whether altered prohormone processing is a causal driver or merely a consequence of diabetes pathology.
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Affiliation(s)
- Adam Ramzy
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Timothy J Kieffer
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada.,Department of Surgery, University of British Columbia, Vancouver, BC, Canada.,School of Biomedical Engineering, University of British Columbia, Vancouver, BC, Canada
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Sanchez Caballero L, Gorgogietas V, Arroyo MN, Igoillo-Esteve M. Molecular mechanisms of β-cell dysfunction and death in monogenic forms of diabetes. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2021; 359:139-256. [PMID: 33832649 DOI: 10.1016/bs.ircmb.2021.02.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Monogenetic forms of diabetes represent 1%-5% of all diabetes cases and are caused by mutations in a single gene. These mutations, that affect genes involved in pancreatic β-cell development, function and survival, or insulin regulation, may be dominant or recessive, inherited or de novo. Most patients with monogenic diabetes are very commonly misdiagnosed as having type 1 or type 2 diabetes. The severity of their symptoms depends on the nature of the mutation, the function of the affected gene and, in some cases, the influence of additional genetic or environmental factors that modulate severity and penetrance. In some patients, diabetes is accompanied by other syndromic features such as deafness, blindness, microcephaly, liver and intestinal defects, among others. The age of diabetes onset may also vary from neonatal until early adulthood manifestations. Since the different mutations result in diverse clinical presentations, patients usually need different treatments that range from just diet and exercise, to the requirement of exogenous insulin or other hypoglycemic drugs, e.g., sulfonylureas or glucagon-like peptide 1 analogs to control their glycemia. As a consequence, awareness and correct diagnosis are crucial for the proper management and treatment of monogenic diabetes patients. In this chapter, we describe mutations causing different monogenic forms of diabetes associated with inadequate pancreas development or impaired β-cell function and survival, and discuss the molecular mechanisms involved in β-cell demise.
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Affiliation(s)
- Laura Sanchez Caballero
- ULB Center for Diabetes Research (UCDR), Université Libre de Bruxelles, Brussels, Belgium. http://www.ucdr.be/
| | - Vyron Gorgogietas
- ULB Center for Diabetes Research (UCDR), Université Libre de Bruxelles, Brussels, Belgium. http://www.ucdr.be/
| | - Maria Nicol Arroyo
- ULB Center for Diabetes Research (UCDR), Université Libre de Bruxelles, Brussels, Belgium. http://www.ucdr.be/
| | - Mariana Igoillo-Esteve
- ULB Center for Diabetes Research (UCDR), Université Libre de Bruxelles, Brussels, Belgium. http://www.ucdr.be/.
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Wang T, Ding S, Li S, Guo H, Chen X, Huang Y, Huang J, Wu J, Hu C, Fang C, Hu J. A novel mutation in INS gene linked to permanent neonatal diabetes mellitus. Endocrine 2019; 64:719-723. [PMID: 30915639 DOI: 10.1007/s12020-019-01905-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2019] [Accepted: 03/14/2019] [Indexed: 12/14/2022]
Abstract
PURPOSE Neonatal diabetes mellitus (NDM) is caused by mutations in the genes responsible for pancreatic β cell mass or function. This study aimed to screen the mutations in the KCNJ11, ABCC8, and INS genes in a Chinese patient with clinical features of NDM. METHODS The entire coding sequence and exon/intron boundaries of KCNJ11, ABCC8, and INS genes were detected by Sanger sequencing. The pathogenicity of the mutation was determined by using online prediction programs SIFT and Mutation Taser. The conformational alterations which contribute to the change of protein function were analyzed at the structural level. RESULTS A novel mutation L35Q (B11) of the INS gene was discovered in the patient. As L35 residue contributes to its hydrophobic core of the protein, the L35Q substitution is predicated to affect B19-A20 disulfide bond and therefore disrupt the folding of the proinsulin, which ultimately results in beta cell apoptosis by inducing ER stress. CONCLUSIONS This case could help us understand the role of the INS mutation in the development of diabetes.
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Affiliation(s)
- Tao Wang
- Department of Endocrinology, The Second Affiliated Hospital of Soochow University, 215004, Suzhou, China
| | - Sisi Ding
- Jiangsu Institute of Clinical Immunology & Jiangsu Key Laboratory of Clinical Immunology, Jiangsu Key Laboratory of Clinical Immunology, First Affiliated Hospital of Soochow University, No.708 Ren-min Road, Suzhou, China
| | - Sicheng Li
- Department of Endocrinology, The Second Affiliated Hospital of Soochow University, 215004, Suzhou, China
| | - Heming Guo
- Department of Endocrinology, The Second Affiliated Hospital of Soochow University, 215004, Suzhou, China
| | - Xiaohong Chen
- Department of Endocrinology, The Second Affiliated Hospital of Soochow University, 215004, Suzhou, China
| | - Yun Huang
- Department of Endocrinology, The Second Affiliated Hospital of Soochow University, 215004, Suzhou, China
| | - Jian Huang
- School of Basic Medicine and Biological Sciences, Medical College of Soochow University, 215123, Suzhou, China
| | - Jianwu Wu
- Department of General Surgery, Affiliated Suzhou Hospital of Nanjing Medical University, Suzhou Municipal Hospital, 26 Daoqian Street, Gusu District, 215002, Suzhou, China
| | - Cheng Hu
- Shanghai Diabetes Institute, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Clinical Centre for Diabetes, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 200233, Shanghai, China
| | - Chen Fang
- Department of Endocrinology, The Second Affiliated Hospital of Soochow University, 215004, Suzhou, China.
| | - Ji Hu
- Department of Endocrinology, The Second Affiliated Hospital of Soochow University, 215004, Suzhou, China.
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Røder ME. Hyperproinsulinemia in obesity and in type 2 diabetes and its relation to cardiovascular disease. Expert Rev Endocrinol Metab 2017; 12:227-239. [PMID: 30058886 DOI: 10.1080/17446651.2017.1331735] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Disproportionately elevated fasting levels of proinsulin immunoreactive material (PIM)relative to insulin immunoreactivity (IRI) are a well-established abnormality in type 2 diabetes. Thesignificance of this abnormality has been investigated and discussed in several studies. Areas covered: The present review focuses on the role of proinsulin and its conversion intermediates inthe development of type 2 diabetes, obesity and insulin resistance, and the potential role as a marker ofcardiovascular risk, including the most important studies in this field. Expert commentary: The composition of plasma PIM is heterogeneous comprising des(31,32)-proinsulin,intact proinsulin and small amounts of des(64,65)-proinsulin. Disproportionate hyperproinsulinemiaseems to occur early in the development and before the diagnosis of type 2 diabetes, and seemsassociated to disease progression. Obesity and insulin resistance does not influence fasting PIM/IRI levels in type 2 diabetes. Fasting PIM/IRI levels in type 2 diabetes are closely associated with the degree of impairment in insulin secretory capacity. Different type 2 diabetes alleles have been described associated with elevated PIM/IRI levels. Recent data suggests that proinsulin and its conversion intermediates may have a role as markers of increased risk of cardiovascular disease in glucose intolerance and type 2 diabetes.
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Affiliation(s)
- Michael E Røder
- a Center for Diabetes Research , Gentofte Hospital , Hellerup , Denmark
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Liu M, Sun J, Cui J, Chen W, Guo H, Barbetti F, Arvan P. INS-gene mutations: from genetics and beta cell biology to clinical disease. Mol Aspects Med 2014; 42:3-18. [PMID: 25542748 DOI: 10.1016/j.mam.2014.12.001] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Revised: 12/02/2014] [Accepted: 12/04/2014] [Indexed: 02/06/2023]
Abstract
A growing list of insulin gene mutations causing a new form of monogenic diabetes has drawn increasing attention over the past seven years. The mutations have been identified in the untranslated regions of the insulin gene as well as the coding sequence of preproinsulin including within the signal peptide, insulin B-chain, C-peptide, insulin A-chain, and the proteolytic cleavage sites both for signal peptidase and the prohormone convertases. These mutations affect a variety of different steps of insulin biosynthesis in pancreatic beta cells. Importantly, although many of these mutations cause proinsulin misfolding with early onset autosomal dominant diabetes, some of the mutant alleles appear to engage different cellular and molecular mechanisms that underlie beta cell failure and diabetes. In this article, we review the most recent advances in the field and discuss challenges as well as potential strategies to prevent/delay the development and progression of autosomal dominant diabetes caused by INS-gene mutations. It is worth noting that although diabetes caused by INS gene mutations is rare, increasing evidence suggests that defects in the pathway of insulin biosynthesis may also be involved in the progression of more common types of diabetes. Collectively, the (pre)proinsulin mutants provide insightful molecular models to better understand the pathogenesis of all forms of diabetes in which preproinsulin processing defects, proinsulin misfolding, and ER stress are involved.
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Affiliation(s)
- Ming Liu
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, 300052, China; Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical School, Ann Arbor, MI, 48105, USA.
| | - Jinhong Sun
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical School, Ann Arbor, MI, 48105, USA
| | - Jinqiu Cui
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, 300052, China
| | - Wei Chen
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical School, Ann Arbor, MI, 48105, USA
| | - Huan Guo
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical School, Ann Arbor, MI, 48105, USA
| | - Fabrizio Barbetti
- Department of Experimental Medicine, University of Tor Vergata, Rome and Bambino Gesù Children's Hospital, Rome, Italy
| | - Peter Arvan
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical School, Ann Arbor, MI, 48105, USA.
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The role of the unfolded protein response in diabetes mellitus. Semin Immunopathol 2013; 35:333-50. [PMID: 23529219 DOI: 10.1007/s00281-013-0369-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Accepted: 03/13/2013] [Indexed: 12/13/2022]
Abstract
The endoplasmic reticulum (ER) plays a key role in the synthesis and modification of secretory and membrane proteins in all eukaryotic cells. Under normal conditions, these proteins are correctly folded and assembled in the ER. However, when cells are exposed to environmental factors such as overproduction of ER proteins, viral infections, or glucose deprivation, the secretory and membrane proteins can accumulate in unfolded or misfolded forms in the lumen of the ER, and consequently, cause stress in the ER. To maintain cellular homeostasis, cells induce several responses to ER stress. In mammalian cells, ER stress responses are induced by a diversity of signal pathways. There are three ER-located transmembrane proteins that play important roles in mammalian ER stress responses: activating transcription factor 6, inositol-requiring protein 1, and protein kinase RNA-like endoplasmic reticulum kinase. ER stress is linked to various diseases, including diabetes. This review highlights the particular importance of ER stress-responsive molecules in insulin biosynthesis, glyconeogenesis, insulin resistance, glucose intolerance, and pancreatic β-cell apoptosis. An understanding of the pathogenic mechanism of diabetes from the aspect of ER stress is crucial in formulating therapeutic strategies.
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Oran PE, Jarvis JW, Borges CR, Sherma ND, Nelson RW. Mass spectrometric immunoassay of intact insulin and related variants for population proteomics studies. Proteomics Clin Appl 2011; 5:454-9. [PMID: 21656909 DOI: 10.1002/prca.201000112] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2010] [Revised: 02/24/2011] [Accepted: 03/03/2011] [Indexed: 11/10/2022]
Abstract
PURPOSE The purpose of the work presented herein was to develop a high-throughput assay for the quantification of human insulin in plasma samples while simultaneously detecting, with high mass accuracy, any additional variant forms of insulin that might be present in each sample. EXPERIMENTAL DESIGN A mass spectrometric immunoassay (MSIA) was designed in which anti-human insulin antibodies were immobilized to commercially available mass spectrometric immunoassay pipette tips and used to capture insulin and related protein variants from human plasma. RESULTS Standard curves for insulin exhibited linearity (average R(2) for three days of analysis=0.99) and assay concentration limits of detection and limits of quantification for insulin were found to be 1 and 15 pM, respectively. Estimated coefficient of variations for inter-day experiments (n=3 days) were <8%. Simultaneously, the assay was shown to detect and identify insulin metabolites and synthetic insulin analogs (e.g. Lantus). Notably, insulin variants not known to exist in plasma were detected in diabetics. CONCLUSIONS AND CLINICAL RELEVANCE This introductory study sets a foundation toward the screening of large populations to investigate insulin isoforms, isoform frequencies, and their quantification.
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Affiliation(s)
- Paul E Oran
- Molecular Biomarkers, The Biodesign Institute at Arizona State University, Tempe, AZ 85287, USA
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Abstract
Some mutations of the insulin gene cause hyperinsulinemia or hyperproinsulinemia. Replacement of biologically important amino acid leads to defective receptor binding, longer half-life and hyperinsulinemia. Three mutant insulins have been identified: (i) insulin Chicago (F49L or PheB25Leu); (ii) insulin Los Angeles (F48S or PheB24Ser); (iii) and insulin Wakayama (V92L or ValA3Leu). Replacement of amino acid is necessary for proinsulin processing results in hyperproinsulinemia. Four types have been identified: (i) proinsulin Providence (H34D); (ii) proinsulin Tokyo (R89H); (iii) proinsulin Kyoto (R89L); and (iv) proinsulin Oxford (R89P). Three of these are processing site mutations. The mutation of proinsulin Providence, in contrast, is thought to cause sorting abnormality. Compared with normal proinsulin, a significant amount of proinsulin Providence enters the constitutive pathway where processing does not occur. These insulin gene mutations with hyper(pro)insulinemia were very rare, showed only mild diabetes or glucose intolerance, and hyper(pro)insulinemia was the key for their diagnosis. However, this situation changed dramatically after the identification of insulin gene mutations as a cause of neonatal diabetes. This class of insulin gene mutations does not show hyper(pro)insulinemia. Mutations at the cysteine residue or creating a new cysteine will disturb the correct disulfide bonding and proper conformation, and finally will lead to misfolded proinsulin accumulation, endoplasmic reticulum stress and apoptosis of pancreatic β-cells. Maturity-onset diabetes of the young (MODY) or an autoantibody-negative type 1-like phenotype has also been reported. Very recently, recessive mutations with reduced insulin biosynthesis have been reported. The importance of insulin gene mutation in the pathogenesis of diabetes will increase a great deal and give us a new understanding of β-cell biology and diabetes. (J Diabetes Invest, doi: 10.1111/j.2040-1124.2011.00100.x, 2011).
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Affiliation(s)
- Masahiro Nishi
- Department of Metabolism and Clinical Nutrition, Wakayama Medical University
| | - Kishio Nanjo
- Research Center of Rural Medicine, Nachi‐Katsuura Spa Hospital, Wakayama, Japan
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Musshoff F, Hess C, Madea B. Disorders of glucose metabolism: post mortem analyses in forensic cases–part II. Int J Legal Med 2010; 125:171-80. [DOI: 10.1007/s00414-010-0510-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Accepted: 08/24/2010] [Indexed: 11/24/2022]
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Støy J, Steiner DF, Park SY, Ye H, Philipson LH, Bell GI. Clinical and molecular genetics of neonatal diabetes due to mutations in the insulin gene. Rev Endocr Metab Disord 2010; 11:205-15. [PMID: 20938745 PMCID: PMC2974937 DOI: 10.1007/s11154-010-9151-3] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Abstract
Over the last decade our insight into the causes of neonatal diabetes has greatly expanded. Neonatal diabetes was once considered a variant of type 1 diabetes that presented early in life. Recent advances in our understanding of this disorder have established that neonatal diabetes is not an autoimmune disease, but rather is a monogenic form of diabetes resulting from mutations in a number of different genes encoding proteins that play a key role in the normal function of the pancreatic beta-cell. Moreover, a correct genetic diagnosis can affect treatment and clinical outcome. This is especially true for patients with mutations in the genes KCNJ11 or ABCC8 that encode the two protein subunits (Kir6.2 and SUR1, respectively) of the ATP-sensitive potassium channel. These patients can be treated with oral sulfonylurea drugs with better glycemic control and quality of life. Recently, mutations in the insulin gene (INS) itself have been identified as another cause of neonatal diabetes. In this article, we review the role of INS mutations in the pathophysiology of neonatal diabetes.
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Affiliation(s)
- Julie Støy
- Department of Internal Medicine and Endocrinology, Aarhus University Hospital, Nørrebrogade 44, 8000, Aarhus C, Denmark.
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Meur G, Simon A, Harun N, Virally M, Dechaume A, Bonnefond A, Fetita S, Tarasov AI, Guillausseau PJ, Boesgaard TW, Pedersen O, Hansen T, Polak M, Gautier JF, Froguel P, Rutter GA, Vaxillaire M. Insulin gene mutations resulting in early-onset diabetes: marked differences in clinical presentation, metabolic status, and pathogenic effect through endoplasmic reticulum retention. Diabetes 2010; 59:653-61. [PMID: 20007936 PMCID: PMC2828668 DOI: 10.2337/db09-1091] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE Heterozygous mutations in the human preproinsulin (INS) gene are a cause of nonsyndromic neonatal or early-infancy diabetes. Here, we sought to identify INS mutations associated with maturity-onset diabetes of the young (MODY) or nonautoimmune diabetes in mid-adult life, and to explore the molecular mechanisms involved. RESEARCH DESIGN AND METHODS The INS gene was sequenced in 16 French probands with unexplained MODY, 95 patients with nonautoimmune early-onset diabetes (diagnosed at <35 years) and 292 normoglycemic control subjects of French origin. Three identified insulin mutants were generated by site-directed mutagenesis of cDNA encoding a preproinsulin-green fluorescent protein (GFP) (C-peptide) chimera. Intracellular targeting was assessed in clonal beta-cells by immunocytochemistry and proinsulin secretion, by radioimmunoassay. Spliced XBP1 and C/EBP homologous protein were quantitated by real-time PCR. RESULTS A novel coding mutation, L30M, potentially affecting insulin multimerization, was identified in five diabetic individuals (diabetes onset 17-36 years) in a single family. L30M preproinsulin-GFP fluorescence largely associated with the endoplasmic reticulum (ER) in MIN6 beta-cells, and ER exit was inhibited by approximately 50%. Two additional mutants, R55C (at the B/C junction) and R6H (in the signal peptide), were normally targeted to secretory granules, but nonetheless caused substantial ER stress. CONCLUSIONS We describe three INS mutations cosegregating with early-onset diabetes whose clinical presentation is compatible with MODY. These led to the production of (pre)proinsulin molecules with markedly different trafficking properties and effects on ER stress, demonstrating a range of molecular defects in the beta-cell.
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Affiliation(s)
- Gargi Meur
- Section of Cell Biology, Division of Medicine, Imperial College London, London, U.K
| | - Albane Simon
- Universite Paris Descartes, INSERM U845, Pediatric Endocrinology, Hopital Necker Enfants Malades Paris, Paris, France
| | - Nasret Harun
- Section of Cell Biology, Division of Medicine, Imperial College London, London, U.K
| | - Marie Virally
- Department of Endocrinology and Diabetes, Lariboisière Hospital, University Paris-Diderot Paris-7, Paris, France
| | - Aurélie Dechaume
- Centre National de la Recherche Scientifique-UMR8090, Lille Institute of Biology, Lille 2 University, Pasteur Institute, Lille, France
| | - Amélie Bonnefond
- Centre National de la Recherche Scientifique-UMR8090, Lille Institute of Biology, Lille 2 University, Pasteur Institute, Lille, France
| | - Sabrina Fetita
- Department of Endocrinology and Diabetes, Clinical Investigation Center CIC9504, Saint-Louis Hospital, INSERM, U872, University Paris-Diderot Paris-7, Paris, France
| | - Andrei I. Tarasov
- Section of Cell Biology, Division of Medicine, Imperial College London, London, U.K
| | - Pierre-Jean Guillausseau
- Department of Endocrinology and Diabetes, Lariboisière Hospital, University Paris-Diderot Paris-7, Paris, France
| | | | - Oluf Pedersen
- Hagedorn Research Institute and Steno Diabetes Center, Gentofte, Denmark
- Faculty of Health Science, University of Aarhus, Aarhus, Denmark
- Institute of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Torben Hansen
- Hagedorn Research Institute and Steno Diabetes Center, Gentofte, Denmark
- Faculty of Health Sciences, University of Southern Denmark, Odense, Denmark
| | - Michel Polak
- Universite Paris Descartes, INSERM U845, Pediatric Endocrinology, Hopital Necker Enfants Malades Paris, Paris, France
| | - Jean-François Gautier
- Department of Endocrinology and Diabetes, Clinical Investigation Center CIC9504, Saint-Louis Hospital, INSERM, U872, University Paris-Diderot Paris-7, Paris, France
| | - Philippe Froguel
- Centre National de la Recherche Scientifique-UMR8090, Lille Institute of Biology, Lille 2 University, Pasteur Institute, Lille, France
- Genomic Medicine, Hammersmith Hospital, Imperial College, London, U.K
| | - Guy A. Rutter
- Section of Cell Biology, Division of Medicine, Imperial College London, London, U.K
- Corresponding authors: Guy A. Rutter, , or Philippe Froguel,
| | - Martine Vaxillaire
- Centre National de la Recherche Scientifique-UMR8090, Lille Institute of Biology, Lille 2 University, Pasteur Institute, Lille, France
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Abstract
The preeminent role of the beta cell is to manufacture, store and release insulin. The mature insulin molecule is composed of two polypeptide chains designated as A and B that are joined by two pairs of disulfide bonds with an additional intramolecular disulfide bond in the A chain. However, the two chains of the insulin molecule are not synthesized as separate polypeptide chains but rather are generated by specific proteolytic processing of a larger precursor, proinsulin. This discovery in 1967 and the concept of prohormones changed our view of the biosynthesis of hormones and neuropeptides. It allowed studies of the regulation of insulin biosynthesis that highlighted the key role of glucose. In addition, the C-peptide, the polypeptide that joins the A and B chains in proinsulin and is stored with insulin in the secretory granules and secreted in equimolar amounts, allowed studies of pancreatic beta cell function in vivo including in patients with diabetes. Subsequent studies have identified the specific proteases, prohormone convertases 1/3 and 2 and carboxypeptidase E, that are involved in the conversion of proinsulin to proinsulin intermediates and then to insulin. Disorders of (pro)insulin biosynthesis continue to illuminate important aspects of this pathway, revealing important connections to diabetes pathogenesis. Recent studies of patients with insulin gene mutations that cause permanent neonatal diabetes have identified key residues affecting the folding and structural organization of the preproinsulin molecule and its subsequent processing. These findings have renewed interest in the key role of endoplasmic reticulum function in insulin biosynthesis and the maintainance of normal beta cell health.
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Affiliation(s)
- D F Steiner
- Department of Biochemistry, The University of Chicago, IL 60637, USA.
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Wen JH, Chen YY, Song SJ, Ding J, Gao Y, Hu QK, Feng RP, Liu YZ, Ren GC, Zhang CY, Hong TP, Gao X, Li LS. Paired box 6 (PAX6) regulates glucose metabolism via proinsulin processing mediated by prohormone convertase 1/3 (PC1/3). Diabetologia 2009; 52:504-13. [PMID: 19034419 DOI: 10.1007/s00125-008-1210-x] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2008] [Accepted: 08/20/2008] [Indexed: 11/30/2022]
Abstract
AIMS/HYPOTHESIS Human patients with aniridia caused by heterozygous PAX6 mutations display abnormal glucose metabolism, but the underlying molecular mechanism is largely unknown. Disturbed islet architecture has been proposed as the reason why mice with complete inactivation of paired box 6 (PAX6) in the pancreas develop diabetes. This is not, however, the case in human aniridia patients with heterozygous PAX6 deficiency and no apparent defects in pancreatic development. We investigated the molecular mechanism underlying the development of abnormal glucose metabolism in these patients. METHODS A human aniridia pedigree with a PAX6 R240Stop mutation was examined for abnormal glucose metabolism using an OGTT. The underlying mechanism was further investigated using Pax6 R266Stop mutant small-eye mice, which also have abnormal glucose metabolism similar to that in PAX6 R240Stop mutation human aniridia patients. RESULTS Paired box 6 (PAX6) deficiency, both in aniridia patients with a heterozygous PAX6 R240Stop mutation and in mice with a heterozygous Pax6 R266Stop mutation, causes defective proinsulin processing and abnormal glucose metabolism. PAX6 can bind to the promoter and directly upregulate production of prohormone convertase (PC)1/3, an enzyme essential for conversion of proinsulin to insulin. Pax6 mutations lead to PC1/3 deficiency, resulting in defective proinsulin processing and abnormal glucose metabolism. CONCLUSIONS/INTERPRETATION This study indicates a novel function for PAX6 in the regulation of proinsulin processing and glucose metabolism via modulation of PC1/3 production. It also provides an insight into the abnormal glucose metabolism caused by heterozygous PAX6 mutations in humans and mice.
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Affiliation(s)
- J H Wen
- Peking University Stem Cell Research Center, China-Australian Center of Excellence for Stem Cell Sciences, Beijing, People's Republic of China
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14
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Colombo C, Porzio O, Liu M, Massa O, Vasta M, Salardi S, Beccaria L, Monciotti C, Toni S, Pedersen O, Hansen T, Federici L, Pesavento R, Cadario F, Federici G, Ghirri P, Arvan P, Iafusco D, Barbetti F. Seven mutations in the human insulin gene linked to permanent neonatal/infancy-onset diabetes mellitus. J Clin Invest 2008; 118:2148-56. [PMID: 18451997 DOI: 10.1172/jci33777] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2007] [Accepted: 03/19/2008] [Indexed: 11/17/2022] Open
Abstract
Permanent neonatal diabetes mellitus (PNDM) is a rare disorder usually presenting within 6 months of birth. Although several genes have been linked to this disorder, in almost half the cases documented in Italy, the genetic cause remains unknown. Because the Akita mouse bearing a mutation in the Ins2 gene exhibits PNDM associated with pancreatic beta cell apoptosis, we sequenced the human insulin gene in PNDM subjects with unidentified mutations. We discovered 7 heterozygous mutations in 10 unrelated probands. In 8 of these patients, insulin secretion was detectable at diabetes onset, but rapidly declined over time. When these mutant proinsulins were expressed in HEK293 cells, we observed defects in insulin protein folding and secretion. In these experiments, expression of the mutant proinsulins was also associated with increased Grp78 protein expression and XBP1 mRNA splicing, 2 markers of endoplasmic reticulum stress, and with increased apoptosis. Similarly transfected INS-1E insulinoma cells had diminished viability compared with those expressing WT proinsulin. In conclusion, we find that mutations in the insulin gene that promote proinsulin misfolding may cause PNDM.
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Affiliation(s)
- Carlo Colombo
- Laboratory of Molecular Endocrinology and Metabolism, Bambino Gesù Children's Hospital, Scientific Institute and Department of Internal Medicine, University of Tor Vergata, Rome, Italy
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15
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Affiliation(s)
- Benjamin Glaser
- Endocrinology and Metabolism Service, Internal Medicine Department, Hadassah-Hebrew University Medical School, Jerusalem, Israel.
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16
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Wan ZL, Huang K, Xu B, Hu SQ, Wang S, Chu YC, Katsoyannis PG, Weiss MA. Diabetes-Associated Mutations in Human Insulin: Crystal Structure and Photo-Cross-Linking Studies of A-Chain Variant InsulinWakayama†,‡. Biochemistry 2005; 44:5000-16. [PMID: 15794638 DOI: 10.1021/bi047585k] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Naturally occurring mutations in insulin associated with diabetes mellitus identify critical determinants of its biological activity. Here, we describe the crystal structure of insulin Wakayama, a clinical variant in which a conserved valine in the A chain (residue A3) is substituted by leucine. The substitution occurs within a crevice adjoining the classical receptor-binding surface and impairs receptor binding by 500-fold, an unusually severe decrement among mutant insulins. To resolve whether such decreased activity is directly or indirectly mediated by the variant side chain, we have determined the crystal structure of Leu(A3)-insulin and investigated the photo-cross-linking properties of an A3 analogue containing p-azidophenylalanine. The structure, characterized in a novel crystal form as an R(6) zinc hexamer at 2.3 A resolution, is essentially identical to that of the wild-type R(6) hexamer. The variant side chain remains buried in a nativelike crevice with small adjustments in surrounding side chains. The corresponding photoactivatable analogue, although of low affinity, exhibits efficient cross-linking to the insulin receptor. The site of photo-cross-linking lies within a 14 kDa C-terminal domain of the alpha-subunit. This domain, unrelated in sequence to the major insulin-binding region in the N-terminal L1 beta-helix, is also contacted by photoactivatable probes at positions A8 and B25. Packing of Val(A3) at this interface may require a conformational change in the B chain to expose the A3-related crevice. The structure of insulin Wakayama thus evokes the reasoning of Sherlock Holmes in "the curious incident of the dog in the night": the apparent absence of structural perturbations (like the dog that did not bark) provides a critical clue to the function of a hidden receptor-binding surface.
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Affiliation(s)
- Zhu-li Wan
- Department of Biochemistry, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4935, USA
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17
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Dhanvantari S, Shen FS, Adams T, Snell CR, Zhang C, Mackin RB, Morris SJ, Loh YP. Disruption of a receptor-mediated mechanism for intracellular sorting of proinsulin in familial hyperproinsulinemia. Mol Endocrinol 2003; 17:1856-67. [PMID: 12829804 DOI: 10.1210/me.2002-0380] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
In familial hyperproinsulinemia, specific mutations in the proinsulin gene are linked with a profound increase in circulating plasma proinsulin levels. However, the molecular and cellular basis for this disease remains uncharacterized. Here we investigated how these mutations may disrupt the sorting signal required to target proinsulin to the secretory granules of the regulated secretory pathway, resulting in the unregulated release of proinsulin. Using a combination of molecular modeling and site-directed mutagenesis, we have identified structural molecular motifs in proinsulin that are necessary for correct sorting into secretory granules of endocrine cells. We show that membrane carboxypeptidase E (CPE), previously identified as a prohormone-sorting receptor, is essential for proinsulin sorting. This was demonstrated through short interfering RNA-mediated depletion of CPE and transfection with a dominant negative mutant of CPE in a beta-cell line. Mutant proinsulins found in familial hyperproinsulinemia failed to bind to CPE and were not sorted efficiently. These findings provide evidence that the elevation of plasma proinsulin levels found in patients with familial hyperproinsulinemia is caused by the disruption of CPE-mediated sorting of mutant proinsulins to the regulated secretory pathway.
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Affiliation(s)
- Savita Dhanvantari
- Section on Cellular Neurobiology, National Institutes of Health, Bethesda, Maryland 20892-4480, USA
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18
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Liu Y, Shen W, Brubaker PL, Kaestner KH, Drucker DJ. Foxa3 (HNF-3gamma) binds to and activates the rat proglucagon gene promoter but is not essential for proglucagon gene expression. Biochem J 2002; 366:633-41. [PMID: 12000309 PMCID: PMC1222783 DOI: 10.1042/bj20020095] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2002] [Revised: 04/19/2002] [Accepted: 05/09/2002] [Indexed: 12/13/2022]
Abstract
Members of the Forkhead box a (Foxa) transcription factor family are expressed in the liver, pancreatic islets and intestine and both Foxa1 and Foxa2 regulate proglucagon gene transcription. As Foxa proteins exhibit overlapping DNA-binding specificities, we examined the role of Foxa3 [hepatocyte nuclear factor (HNF)-3gamma] in control of proglucagon gene expression. Foxa3 was detected by reverse transcriptase PCR in glucagon-producing cell lines and binds to the rat proglucagon gene G2 promoter element in GLUTag enteroendocrine cells. Although Foxa3 increased rat proglucagon promoter activity in BHK fibroblasts, augmentation of Foxa3 expression did not increase proglucagon promoter activity in GLUTag cells. Furthermore, adenoviral Foxa3 expression did not affect endogenous proglucagon gene expression in islet or intestinal endocrine cell lines. Although Foxa3(-/-) mice exhibit mild hypoglycaemia during a prolonged fast, the levels of proglucagon-derived peptides and proglucagon mRNA transcripts were comparable in tissues from wild-type and Foxa3(-/-) mice. These findings identify Foxa3 as a member of the proglucagon gene G2 element binding-protein family that, unlike Foxa1, is not essential for control of islet or intestinal proglucagon gene expression in vivo.
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Affiliation(s)
- Yuanfang Liu
- Department of Medicine, Banting and Best Diabetes Centre, Toronto General Hospital, University of Toronto, 101 College Street CCRW3-845, Toronto, Canada M5G 2C4
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19
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20
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Abstract
Processing of proproteins to biologically active peptides and, in the case of peptide hormones and neuropeptides, their sorting to granules of the regulated secretory pathway, requires the concerted action of a cascade of enzymes and chaperones. The purpose of this review is to summarize the recent emerging knowledge of how these molecules affect specific endocrine systems. This has come about through the study of gene knockout mice as well as endocrinopathies resulting from mutated genes in humans.
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Affiliation(s)
- L Canaff
- Department of Medicine, McGill University, Montreal, Quebec, Canada
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21
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Pathogenesis of non-insulin-dependent (type II) diabetes mellitus (NIDDM) - genetic predisposition and metabolic abnormalities. Adv Drug Deliv Rev 1999; 35:157-177. [PMID: 10837696 DOI: 10.1016/s0169-409x(98)00071-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Non-insulin-dependent diabetes mellitus (NIDDM), also known as type II diabetes, is characterized by abnormal glucose homeostasis, resulting in hyperglycemia, and is associated with microvascular, macrovascular, and neuropathic complications. NIDDM is a complex disease with many causes. Both genetic and environmental factors play important roles in the pathogenesis of NIDDM. Cumulative evidence on the high prevalence of NIDDM in certain ethnic groups, the high concordance rate for the disease in monozygotic twins, familial aggregation, and familial transmission patterns suggests that the genetic component plays an important etiological role in the development of NIDDM. In genetically predisposed individuals, there is a slow progression from a normal state to hyperglycemia, largely due to a combination of insulin resistance and defects in insulin secretion. Although numerous candidate genes responsible for insulin resistance and for the defects in insulin secretion have been reported, no specific gene(s) accounting for the majority of cases of the common type of NIDDM has been identified. Considerable evidence indicates that environmental and other factors, including diet, stress, physical activity, obesity and aging, also play an important role in the development of the disease. In conclusion, the pathogenic process of NIDDM depends on a complex interaction between genetic and environmental factors.
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22
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Abstract
The majority of peptide hormones and neuropeptides are synthesized as precursors, which are cleaved in a sequence-specific and tissue-specific manner to yield the biologically active peptides. There has been considerable progress in the past ten years in understanding the nature and mechanism of action of the prohormone convertases that cleave these prohormones. Evidence from knockout technology and clinical examples of gene mutations has provided functional information on disruption of prohormone cleavage and the bioactivity of prohormones. There are specific examples of the clinical relevance of circulating prohormones, such as adrenocorticotrophin (ACTH) precursors and proinsulin. The central issues that still remain are: (1) What is the relative importance of each of the different processing pathways and processing enzymes in regulating hormone action? (2) How do the serum concentrations of prohormones compare with the mature hormone levels? (3) What are the biological consequences of prohormones in the circulation?
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Affiliation(s)
- H E Wilson
- Endocrine Sciences Research Group, and Departments of Medicine and Child Health, University of Manchester, Manchester, UK
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23
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Houssa P, Dinesen B, Deberg M, Frank BH, Van Schravendijk C, Sodoyez-Goffaux F, Sodoyez JC. First direct assay for intact human proinsulin. Clin Chem 1998. [DOI: 10.1093/clinchem/44.7.1514] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
AbstractWe describe a sensitive two-site sandwich enzyme-linked immunosorbent assay for the measurement of intact human proinsulin in 100 μL of serum or plasma. The assay is based on the use of two monoclonal antibodies specific for epitopes at the C-peptide/insulin A chain junction and at the insulin B chain/C-peptide junction, respectively. Cross-reactivities with insulin, C-peptide, and the four proinsulin conversion intermediates were negligible. The detection limit in buffer was 0.2 pmol/L (3 standard deviations from zero). The working range was 0.2–100 pmol/L. The mean intra- and interassay coefficients of variation were 2.4% and 8.9%, respectively. The mean recovery of added proinsulin was 103%. Dilution curves of 40 serum samples are parallel to the proinsulin calibration curve. Proinsulin concentrations in 20 fasting healthy subjects were all above the limit of detection: median (range), 2.7 pmol/L (1.1–6.9 pmol/L). Six fasting non-insulin-dependent diabetes mellitus and five insulinoma patients had proinsulin concentrations significantly higher than healthy subjects: median (range), 7.7 pmol/L (3.2–18 pmol/L) and 153 pmol/L (98–320 pmol/L), respectively.
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Affiliation(s)
- Paule Houssa
- University of Liège, Division of Nuclear Pediatrics, Sart Tilman, 4000 Liège, Belgium
| | - Bo Dinesen
- Steno Diabetes Center, Niels Steensens Vej 2, 2820 Gentofte, Denmark
| | - Michelle Deberg
- University of Liège, Division of Nuclear Pediatrics, Sart Tilman, 4000 Liège, Belgium
| | - Bruce H Frank
- Lilly Research Laboratories, 307 East Mccarty Street, Indianapolis, IN 46285
| | - Chris Van Schravendijk
- Fakulteit Geneeskunde in Farmacie, Laarbeeklaan 103, Vrije Universiteit, 1000 Brussels, Belgium
| | | | - Jean-Claude Sodoyez
- University of Liège, Division of Nuclear Pediatrics, Sart Tilman, 4000 Liège, Belgium
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24
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Nara Y, Gao M, Ikeda K, Sato T, Sawamura M, Kawano K, Yamori Y. Genetic analysis of non-insulin-dependent diabetes mellitus in the Otsuka Long-Evans Tokushima Fatty rat. Biochem Biophys Res Commun 1997; 241:200-4. [PMID: 9405257 DOI: 10.1006/bbrc.1997.7347] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The Otsuka Long-Evans Tokushima Fatty (OLETF) rat is an animal model for obese NIDDM. We performed a genome wide scan in F2 progenies obtained by crossing OLETF rats with two control strains, Long-Evans Tokushima Otsuka (LETO) and Fisher-344(F-344) rats. Since diabetes develops only in male progenies, we used only male F2 rats for the linkage studies.Highly significant linkage was observed between the phenotype, postprandial hyperglycemia and P-450ald locus on chromosome 1 and D7Mit 11 locus on chromosome 7. In addition, suggestive linkage was found between fasting glucose level and body weight and these two loci. Four other regions (D1Mit12, D2Mit11, D5Mgh14, and D17Arb1) on chromosome 1, 2, 5, and 17 were detected to influence body weight, fasting glucose level or postprandial hyperglycemia independently. We concluded that non-insulin-dependent diabetes mellitus(NIDDM) in OLETF rats is regulated by multiple genes which affect fasting, postprandial hyperglycemia, and obesity differently.
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Affiliation(s)
- Y Nara
- Department of Enviromental Conservation and Development, Kyoto University, Kyoto, 606, Japan
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25
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Warren-Perry MG, Manley SE, Ostrega D, Polonsky K, Mussett S, Brown P, Turner RC. A novel point mutation in the insulin gene giving rise to hyperproinsulinemia. J Clin Endocrinol Metab 1997; 82:1629-31. [PMID: 9141561 DOI: 10.1210/jcem.82.5.3914] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A 58-yr-old obese white Caucasian male type 2 diabetic, entered into the UK Prospective Diabetes Study, was found to have raised fasting total proinsulin levels 708 pmol/L(-1) (normal range, 3-16 pmol/L(-1)) and normal specific plasma insulin level 29 pmol/L(-1) (normal range, 21-75 pmol/L(-1)). Immunoreactive plasma insulin, measured by RIA, was 503 pmol/L(-1). DNA was extracted, the insulin gene amplified by the PCR, and by direct sequencing, a novel point mutation, G1552C, was identified, which resulted in the substitution of proline (CCT) for arginine (CGT) at position 65. This prevented cleavage of the C-peptide A-chain dibasic cleavage site (lys-arg) by the processing protease in the pancreatic beta-cells. The plasma proinsulin and insulin levels were in accord with expression of both the wild-type and the mutant alleles. The G1552C mutation was not linked with diabetes, because it was present in a 37-yr-old nondiabetic daughter and not in a 35-yr-old daughter who had had gestational diabetes.
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Affiliation(s)
- M G Warren-Perry
- Diabetes Research Laboratories, Radcliffe Infirmary, Oxford, England
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26
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Barbetti F. Pathophysiology of non-insulin-dependent diabetes and the search for candidate genes: dangerous liaisons? Acta Diabetol 1996; 33:257-62. [PMID: 9033964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- F Barbetti
- H. San Raffaele Scientific Institute, Milan, Italy
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27
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Ura S, Araki E, Kishikawa H, Shirotani T, Todaka M, Isami S, Shimoda S, Yoshimura R, Matsuda K, Motoyoshi S, Miyamura N, Kahn CR, Shichiri M. Molecular scanning of the insulin receptor substrate-1 (IRS-1) gene in Japanese patients with NIDDM: identification of five novel polymorphisms. Diabetologia 1996; 39:600-8. [PMID: 8739921 DOI: 10.1007/bf00403308] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Since the insulin receptor substrate-1 (IRS-1) is the major substrate of the insulin receptor tyrosine kinase and has been shown to activate phosphatidylinositol (PI) 3-kinase and promote GLUT4 translocation, the IRS-1 gene is a potential candidate for development of non-insulin-dependent diabetes mellitus (NIDDM). In this study, we have identified IRS-1 gene polymorphisms, evaluated their frequencies in Japanese subjects, and analysed the contribution of these polymorphisms to the development of NIDDM. The entire coding region of the IRS-1 gene of 94 subjects (47 NIDDM and 47 control subjects) was screened by polymerase chain reaction-single stranded conformation polymorphism (PCR-SSCP) analysis. Seven SSCP polymorphisms were identified. These corresponded to two previously identified polymorphisms [Gly971 --> Arg (GGG --> AGG) and Ala804 (GCA --> GCG)] as well as five novel polymorphisms [Pro190 --> Arg (CCC --> CGC), Met209 --> Thr (ATG --> ACG), Ser809 --> Phe (TCT --> TTT), Leu142 (CTT --> CTC), and Gly625 (GGC --> GGT)]. Although the prevalence of each of these polymorphisms was not statistically different between NIDDM and control subjects, the prevalence of the four IRS-1 polymorphisms with an amino acid substitution together was significantly higher in NIDDM than in control subjects (23.4 vs 8.5%, p < 0.05), and two substitutions (Met 209 --> Thr and Ser809 --> Phe) were found only in NIDDM patients. Equilibrium glucose infusion rates during a euglycaemic clamp in NIDDM and control subjects with the IRS-1 polymorphisms decreased by 29.5 and 22.0%, respectively on the average when compared to those in comparable groups without polymorphisms, although they were not statistically significant. Thus, IRS-1 polymorphisms may contribute in part to the insulin resistance and development of NIDDM in Japanese subjects; however, they do not account for the major part of the decrease in insulin-stimulated glucose uptake which is observed in subjects with clinically apparent NIDDM.
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Affiliation(s)
- S Ura
- Department of Metabolic Medicine, Kumamoto University School of Medicine, Japan
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28
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O'Rahilly S, Gray H, Humphreys PJ, Krook A, Polonsky KS, White A, Gibson S, Taylor K, Carr C. Brief report: impaired processing of prohormones associated with abnormalities of glucose homeostasis and adrenal function. N Engl J Med 1995; 333:1386-90. [PMID: 7477119 DOI: 10.1056/nejm199511233332104] [Citation(s) in RCA: 144] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- S O'Rahilly
- Department of Medicine, University of Cambridge, Addenbrooke's Hospital, United Kingdom
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29
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Villard E, Lalau JD, van Hooft IS, Derkx FH, Houot AM, Pinet F, Corvol P, Soubrier F. A mutant renin gene in familial elevation of prorenin. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(18)43813-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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30
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Kim DY, Choi JH, Woo JT, Paeng JR, Yang IM, Kim SW, Kim JW, Kim YS, Kim KW, Choi YK. Polymorphism of glucokinase gene in non-insulin dependent diabetes mellitus. Korean J Intern Med 1994; 9:25-31. [PMID: 7913622 PMCID: PMC4532057 DOI: 10.3904/kjim.1994.9.1.25] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Several lines of evidence suggest a strong genetic component to NIDDM. To clarify the role of glucokinase gene in the development of NIDDM, restriction fragment length polymorphism (RFLP) of glucokinase gene and 3' microsatellite polymorphism analyses by polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP) were performed in NIDDM and control subjects. Compared to NIDDM with 1.3 kb allele/Pvu I digestion of glucokinase, 10% of NIDDM did not demonstrate 1.3 kb allele and these patients were characterized by increased insulin secretion. In 3' microsatellite polymorphism analysis, autoradiography of PCR products revealed three different alleles, including Z, Z + 2 and Z + 4. Z was the most common allele in both NIDDM and nondiabetic controls. There was no significant allele associated with NIDDM. Frequency of the homozygote Z/Z genotype was significantly lower in NIDDM subjects (16.7%) compared to normal control (46.7%)(p < 0.05). There was no difference in clinical findings according to 3' microsatellite genotypes in NIDDM. These data suggest that there does not appear to be a significant glucokinase allele associated with NIDDM but Z/Z genotype may play a suppressive role in the pathogenesis of a certain type of NIDDM in Korea. Further studies may be required to identify the molecular basis of this association.
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Affiliation(s)
- D Y Kim
- Department of Internal Medicine, School of Medicine Kyung-Hee University, Seoul, Korea
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31
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Bolander FF. Molecular Bases of Endocrinopathies. Mol Endocrinol 1994. [DOI: 10.1016/b978-0-12-111231-8.50022-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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32
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Linde S, Welinder BS, Nielsen JH. Analysis of proinsulin and its conversion products by reversed-phase high-performance liquid chromatography. JOURNAL OF CHROMATOGRAPHY 1993; 614:185-204. [PMID: 8314931 DOI: 10.1016/0378-4347(93)80309-r] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Proinsulin is synthesized in the beta-cells of the endocrine pancreas, one of the four cell types found in the islets of Langerhans. Specific enzymatic cleavage of proinsulin results in the formation of equimolar amounts of insulin and C-peptide, via several intermediate split-proinsulin forms. Most mammals produce a single insulin, but in rodents two non-allelic insulin genes are expressed. There is an inverse ratio between the two insulins in rats and mice, the reason for this being unknown. It has been suggested that differences in transcription, translation (biosynthesis) and/or posttranslational processes (enzymatic conversion, intracellular degradation) could be possible explanations. Elevated amounts of proinsulin-immunoreactive material (PIM) have been described to occur in various conditions/diseases, suggesting alterations in beta-cell function, but the composition of the secreted PIM (intact proinsulin or its intermediates) has been incompletely determined. Studies of the biosynthesis of proinsulins and their conversion with the purpose of revealing some of these points depend on accessible reversed-phase high-performance liquid chromatographic (RP-HPLC) analyses capable of separating all the relevant, closely related polypeptides involved. This review will deal with the optimization of the RP-HPLC separations as well as sample preparation and recovery. Applications of the selected methods in the study of proinsulin biosynthesis and its conversion will also be presented.
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Affiliation(s)
- S Linde
- Immunochemical Department, Novo Nordisk A/S, Bagsvaerd, Denmark
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33
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Shimada F, Makino H, Hashimoto N, Taira M, Seino S, Bell GI, Kanatsuka A, Yoshida S. Type 2 (non-insulin-dependent) diabetes mellitus associated with a mutation of the glucokinase gene in a Japanese family. Diabetologia 1993; 36:433-7. [PMID: 8314448 DOI: 10.1007/bf00402280] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Mutations were screened for in the glucokinase gene of 25 Japanese patients with Type 2 (non-insulin-dependent) diabetes mellitus. Each exon was scanned by electrophoresis of enzymatically amplified DNA segments under non-denaturing conditions and variants were sequenced. A variant pattern was detected in exon 5 of one patient. Direct sequencing of this exon revealed a single nucleotide substitution in codon 188 (GCT-->ACT) of one of two alleles resulting in the mutation of Ala188-->Thr, an invariant residue in the sequence of all mammalian glucokinases and hexokinases. This mutation was not found in 40 normal control subjects. The proband had been diagnosed with Type 2 diabetes at the age of 62 years. Four other members of her family have the same mutation and all have Type 2 diabetes or impaired glucose tolerance. The youngest age at diagnosis of Type 2 diabetes in these other members was 13 years, suggesting that her pedigree was maturity-onset diabetes of the young (MODY). All subjects with the Thr188 mutation show a decreased insulin secretory response during oral glucose tolerance testing. Mutations in the glucokinase gene associated with Type 2 diabetes have been previously identified in Caucasian (French and British) subjects. This study indicates that mutations in this gene are also implicated in the development of Type 2 diabetes in Asians. Further studies are required to determine the frequency of mutations in glucokinase among Japanese patients with Type 2 diabetes.
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Affiliation(s)
- F Shimada
- Second Department of Internal Medicine, Chiba, Japan
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34
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Bell GI, Froguel P, Nishi S, Pilkis SJ, Stoffel M, Takeda J, Vionnet N, Yasuda K. Mutations of the human glucokinase gene and diabetes mellitus. Trends Endocrinol Metab 1993; 4:86-90. [PMID: 18407139 DOI: 10.1016/1043-2760(93)90084-r] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The enzyme glucokinase catalyzes the phosphorylation of glucose and plays a key role in the regulation o f insulin secretion by pancreatic beta cells and glucose disposal in hepatocytes. Recent studies have shown that mutations in the gene encoding this key regulatory enzyme of glycolysis are a common cause of an autosomal dominant form of non-insulin-dependent (type 2) diabetes mellitus that has an onset often during childhood. The association of mutations in the glucokinase gene with impaired pancreatic cell function underscores the importance of glycolysis in the regulation of insulin secretion and suggests that mutations in other genes expressed in the beta-cell that also control rate-limiting steps in glucose metabolism may lead to diabetes.
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Affiliation(s)
- G I Bell
- Howard Hughes Medical Institute and Departments of Biochemistry and Molecular Biology and Medicine, The University of Chicago, Chicago, IL 60637, USA
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