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Catli G, Abaci A, Flanagan SE, Anik A, Ellard S, Bober E. Permanent neonatal diabetes caused by a novel mutation in the INS gene. Diabetes Res Clin Pract 2013; 99:e5-8. [PMID: 23107109 DOI: 10.1016/j.diabres.2012.10.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Accepted: 10/04/2012] [Indexed: 11/16/2022]
Abstract
Neonatal diabetes mellitus (DM) is a rare condition that can be either transient or permanent. In this case report, we describe a novel mutation (p.L30Q) in the INS gene resulting in permanent DM in a four-month-old female who presented with polyphagia, polyuria, irritability, and hyperglycemia with glucosuria and ketonuria without acidosis.
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Affiliation(s)
- Gonul Catli
- Department of Pediatric Endocrinology, Dokuz Eylul University, Izmir, Turkey
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52
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Eames SC, Kinkel MD, Rajan S, Prince VE, Philipson LH. Transgenic zebrafish model of the C43G human insulin gene mutation. J Diabetes Investig 2012; 4:157-67. [PMID: 24843647 PMCID: PMC4019270 DOI: 10.1111/jdi.12015] [Citation(s) in RCA: 10] [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: 06/12/2012] [Revised: 08/05/2012] [Accepted: 08/22/2012] [Indexed: 02/06/2023] Open
Abstract
Aims/Introduction The human insulin gene/preproinsulin protein mutation C43G disrupts disulfide bond formation and causes diabetes in humans. Previous in vitro studies showed that these mutant proteins are retained in the endoplasmic reticulum (ER), are not secreted and are associated with decreased secretion of wild‐type insulin. The current study extends this work to an in vivo zebrafish model. We hypothesized that C43G‐green fluorescent protein (GFP) would be retained in the ER, disrupt β‐cell function and lead to impaired glucose homeostasis. Materials and Methods Islets from adult transgenic zebrafish expressing GFP‐tagged human proinsulin mutant C43G (C43G‐GFP) or wild‐type human proinsulin (Cpep‐GFP) were analyzed histologically across a range of ages. Blood glucose concentration was determined under fasting conditions and in response to glucose injection. Insulin secretion was assessed by measuring circulating GFP and endogenous C‐peptide levels after glucose injection. Results The majority of β‐cells expressing C43G proinsulin showed excessive accumulation of C43G‐GFP in the ER. Western blotting showed that C43G‐GFP was present only as proinsulin, indicating defective processing. GFP was poorly secreted in C43G mutants compared with controls. Despite these defects, blood glucose homeostasis was normal. Mutant fish maintained β‐cell mass well into maturity and secreted endogenous C‐peptide. Conclusions In this model, the C43G proinsulin mutation does not impair glucose homeostasis or cause significant loss of β‐cell mass. This model might be useful for identifying potential therapeutic targets for proper trafficking of intracellular insulin or for maintenance of β‐cell mass in early‐stage diabetic patients.
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Affiliation(s)
- Stefani C Eames
- Department of Organismal Biology and Anatomy Chicago IL USA ; Committee on Molecular Metabolism and Nutrition Chicago IL USA
| | - Mary D Kinkel
- Department of Organismal Biology and Anatomy Chicago IL USA
| | - Sindhu Rajan
- Department of Medicine University of Chicago Chicago, Illinois, USA IL USA
| | - Victoria E Prince
- Department of Organismal Biology and Anatomy Chicago IL USA ; Committee on Molecular Metabolism and Nutrition Chicago IL USA
| | - Louis H Philipson
- Committee on Molecular Metabolism and Nutrition Chicago IL USA ; Department of Medicine University of Chicago Chicago, Illinois, USA IL USA
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Rachmiel M, Rubio-Cabezas O, Ellard S, Hattersley AT, Perlman K. Early-onset, severe lipoatrophy in a patient with permanent neonatal diabetes mellitus secondary to a recessive mutation in the INS gene. Pediatr Diabetes 2012; 13:e26-9. [PMID: 21910811 DOI: 10.1111/j.1399-5448.2011.00809.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
We describe a case of neonatal diabetes due to a homozygous mutation (c.3 G>T) at the INS gene, leading to lack of insulin expression and severe hyperglycemia from day one of life requiring permanent insulin replacement therapy. The genetic loss of endogenous insulin production likely led to lack of immune tolerance to insulin, with resultant autoantibody production against exogenous insulin and progressive immune-mediated lipoatrophy at injection sites.
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Affiliation(s)
- Marianna Rachmiel
- Department of Pediatrics, Assaf Harofeh Medical Center, Zerifin (affiliated to Sackler Faculty of Medicine, Tel Aviv University), Israel.
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Vaxillaire M, Bonnefond A, Froguel P. The lessons of early-onset monogenic diabetes for the understanding of diabetes pathogenesis. Best Pract Res Clin Endocrinol Metab 2012; 26:171-87. [PMID: 22498247 DOI: 10.1016/j.beem.2011.12.001] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Monogenic diabetes consists of different subtypes of single gene disorders comprising a large spectrum of phenotypes, namely neonatal diabetes mellitus or monogenic diabetes of infancy, dominantly inherited familial forms of early-onset diabetes (called Maturity-Onset Diabetes of the Young) and rarer diabetes-associated syndromic diseases. All these forms diagnosed at a very-young age are unrelated to auto-immunity. Their genetic dissection has revealed major genes in developmental and/or functional processes of the pancreatic β-cell physiology, and various molecular mechanisms underlying the primary pancreatic defects. Most of these discoveries have had remarkable consequences on the patients care and patient's long-term condition with outstanding examples of successful genomic medicine, which are highlighted in this chapter. Increasing evidence also shows that frequent polymorphisms in or near monogenic diabetes genes may contribute to adult polygenic type 2 diabetes. In this regard, unelucidated forms of monogenic diabetes represent invaluable models for identifying new targets of β-cell dysfunction.
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Affiliation(s)
- Martine Vaxillaire
- Centre National de la Recherche Scientifique UMR, Genomics and Metabolic Diseases, Lille Pasteur Institute, Lille Nord de France University, France.
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Liu M, Lara-Lemus R, Shan SO, Wright J, Haataja L, Barbetti F, Guo H, Larkin D, Arvan P. Impaired cleavage of preproinsulin signal peptide linked to autosomal-dominant diabetes. Diabetes 2012; 61:828-37. [PMID: 22357960 PMCID: PMC3314357 DOI: 10.2337/db11-0878] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Recently, missense mutations upstream of preproinsulin's signal peptide (SP) cleavage site were reported to cause mutant INS gene-induced diabetes of youth (MIDY). Our objective was to understand the molecular pathogenesis using metabolic labeling and assays of proinsulin export and insulin and C-peptide production to examine the earliest events of insulin biosynthesis, highlighting molecular mechanisms underlying β-cell failure plus a novel strategy that might ameliorate the MIDY syndrome. We find that whereas preproinsulin-A(SP23)S is efficiently cleaved, producing authentic proinsulin and insulin, preproinsulin-A(SP24)D is inefficiently cleaved at an improper site, producing two subpopulations of molecules. Both show impaired oxidative folding and are retained in the endoplasmic reticulum (ER). Preproinsulin-A(SP24)D also blocks ER exit of coexpressed wild-type proinsulin, accounting for its dominant-negative behavior. Upon increased expression of ER-oxidoreductin-1, preproinsulin-A(SP24)D remains blocked but oxidative folding of wild-type proinsulin improves, accelerating its ER export and increasing wild-type insulin production. We conclude that the efficiency of SP cleavage is linked to the oxidation of (pre)proinsulin. In turn, impaired (pre)proinsulin oxidation affects ER export of the mutant as well as that of coexpressed wild-type proinsulin. Improving oxidative folding of wild-type proinsulin may provide a feasible way to rescue insulin production in patients with MIDY.
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Affiliation(s)
- Ming Liu
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical Center, Ann Arbor, Michigan
- Tianjin Medical University General Hospital, Tianjin, China
| | - Roberto Lara-Lemus
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical Center, Ann Arbor, Michigan
| | - Shu-ou Shan
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California
| | - Jordan Wright
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical Center, Ann Arbor, Michigan
| | - Leena Haataja
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical Center, Ann Arbor, Michigan
| | - Fabrizio Barbetti
- Laboratory of Molecular Endocrinology and Metabolism, Bambino Gesù Children’s Hospital, Scientific Institute (Istituto Di Ricovero e Cura a Carattere Scientifico), Rome, Italy
| | - Huan Guo
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical Center, Ann Arbor, Michigan
| | - Dennis Larkin
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical Center, Ann Arbor, Michigan
| | - Peter Arvan
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical Center, Ann Arbor, Michigan
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Garin I, Perez de Nanclares G, Gastaldo E, Harries LW, Rubio-Cabezas O, Castaño L. Permanent neonatal diabetes caused by creation of an ectopic splice site within the INS gene. PLoS One 2012; 7:e29205. [PMID: 22235272 PMCID: PMC3250427 DOI: 10.1371/journal.pone.0029205] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Accepted: 11/22/2011] [Indexed: 02/06/2023] Open
Abstract
Background The aim of this study was to characterize the genetic etiology in a patient who presented with permanent neonatal diabetes at 2 months of age. Methodology/Principal Findings Regulatory elements and coding exons 2 and 3 of the INS gene were amplified and sequenced from genomic and complementary DNA samples. A novel heterozygous INS mutation within the terminal intron of the gene was identified in the proband and her affected father. This mutation introduces an ectopic splice site leading to the insertion of 29 nucleotides from the intronic sequence into the mature mRNA, which results in a longer and abnormal transcript. Conclusions/Significance This study highlights the importance of routinely sequencing the exon-intron boundaries and the need to carry out additional studies to confirm the pathogenicity of any identified intronic genetic variants.
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Affiliation(s)
- Intza Garin
- Endocrinology and Diabetes Research Group, Hospital de Cruces, Universitat Politècnica de València/Euskal Herriko Unibertsitateko, Barakaldo, Bizkaia, Spain
- Centro de Investingación Biomèdica en Red de Diabetes y Endermedades Metabólicas (CIBERDM), Centro de investigación Biomèdica en Red de Endermedads Raras (CIBERER), Barakaldo, Bizkaia, Spain
| | - Guiomar Perez de Nanclares
- Endocrinology and Diabetes Research Group, Hospital de Cruces, Universitat Politècnica de València/Euskal Herriko Unibertsitateko, Barakaldo, Bizkaia, Spain
- Centro de Investingación Biomèdica en Red de Diabetes y Endermedades Metabólicas (CIBERDM), Centro de investigación Biomèdica en Red de Endermedads Raras (CIBERER), Barakaldo, Bizkaia, Spain
| | - Elena Gastaldo
- Pediatric Endocrinology, Hospital de La Ribera, Alzira, Valencia, Spain
| | - Lorna W. Harries
- Institute of Biomedical and Clinical Science, Peninsula College of Medicine and Dentistry, Exeter, United Kingdom
| | - Oscar Rubio-Cabezas
- Department of Pediatric Endocrinology, Hospital Infantil Universitario Niño Jesús, Madrid, Spain
- Centro de Investigación Biomédica en Red Fisiopatogía se la obesidad y Nutrición, Instituto de Salud Carlos III, Madrid, Spain
| | - Luis Castaño
- Endocrinology and Diabetes Research Group, Hospital de Cruces, Universitat Politècnica de València/Euskal Herriko Unibertsitateko, Barakaldo, Bizkaia, Spain
- Centro de Investingación Biomèdica en Red de Diabetes y Endermedades Metabólicas (CIBERDM), Centro de investigación Biomèdica en Red de Endermedads Raras (CIBERER), Barakaldo, Bizkaia, Spain
- * E-mail:
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Greeley SAW, Naylor RN, Philipson LH, Bell GI. Neonatal diabetes: an expanding list of genes allows for improved diagnosis and treatment. Curr Diab Rep 2011; 11:519-32. [PMID: 21993633 PMCID: PMC3226065 DOI: 10.1007/s11892-011-0234-7] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
There has been major progress in recent years uncovering the genetic causes of diabetes presenting in the first year of life. Twenty genes have been identified to date. The most common causes accounting for the majority of cases are mutations in the genes encoding the two subunits of the ATP-sensitive potassium channel (K(ATP)), KCNJ11 and ABCC8, and the insulin gene (INS), as well as abnormalities in chromosome 6q24. Patients with activating mutations in KCNJ11 and ABCC8 can be treated with oral sulfonylureas in lieu of insulin injections. This compelling example of personalized genetic medicine leading to improved glucose regulation and quality of life may-with continued research-be repeated for other forms of neonatal diabetes in the future.
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Affiliation(s)
- Siri Atma W Greeley
- Section of Adult and Pediatric Endocrinology, Diabetes and Metabolism, Kovler Diabetes Center, The University of Chicago, Chicago, IL 60637, USA.
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58
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Haldorsen IS, Ræder H, Vesterhus M, Molven A, Njølstad PR. The role of pancreatic imaging in monogenic diabetes mellitus. Nat Rev Endocrinol 2011; 8:148-59. [PMID: 22124438 DOI: 10.1038/nrendo.2011.197] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
In neonatal diabetes mellitus resulting from mutations in EIF2AK3, PTF1A, HNF1B, PDX1 or RFX6, pancreatic aplasia or hypoplasia is typical. In maturity-onset diabetes mellitus of the young (MODY), mutations in HNF1B result in aplasia of pancreatic body and tail, and mutations in CEL lead to lipomatosis. The pancreas is not readily accessible for histopathological investigations and pancreatic imaging might, therefore, prove important for diagnosis, treatment, and research into these β-cell diseases. Advanced imaging techniques can identify the pancreatic features that are characteristic of inherited diabetes subtypes, including alterations in organ size (diffuse atrophy and complete or partial pancreatic agenesis), lipomatosis and calcifications. Consequently, in patients with suspected monogenic diabetes mellitus, the results of pancreatic imaging could help guide the molecular and genetic investigation. Imaging findings also highlight the critical roles of specific genes in normal pancreatic development and differentiation and provide new insight into alterations in pancreatic structure that are relevant for β-cell disease.
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Affiliation(s)
- Ingfrid S Haldorsen
- Department of Radiology, Haukeland University Hospital, N-5021 Bergen, Norway
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59
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Abstract
Diabetes mellitus diagnosed during the first 2 years of life differs from the disease in older children regarding its causes, clinical characteristics, treatment options and needs in terms of education and psychosocial support. Over the past decade, new genetic causes of neonatal diabetes mellitus have been elucidated, including monogenic β-cell defects and chromosome 6q24 abnormalities. In patients with KCNJ11 or ABCC8 mutations and diabetes mellitus, oral sulfonylurea offers an easy and effective treatment option. Type 1 diabetes mellitus in infants is characterized by a more rapid disease onset, poorer residual β-cell function and lower rate of partial remission than in older children. Insulin therapy in infants with type 1 diabetes mellitus or other monogenic causes of diabetes mellitus is a challenge, and novel data highlight the value of continuous subcutaneous insulin infusion in this very young patient population. Infants are entirely dependent on caregivers for insulin therapy, nutrition and glucose monitoring, which emphasizes the need for appropriate education and psychosocial support of parents. To achieve optimal long-term metabolic control with low rates of acute and chronic complications, continuous and structured diabetes care should be provided by a multidisciplinary health-care team.
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Affiliation(s)
- Beate Karges
- Division of Endocrinology and Diabetes, RWTH Aachen University, Pauwelsstraße 30, D-52074 Aachen, Germany.
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60
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Abstract
PURPOSE OF REVIEW The goal of this review is to provide an update on the different forms of monogenic diabetes, including maturity-onset diabetes of the young (MODY) and neonatal diabetes (permanent and transient neonatal diabetes). RECENT FINDINGS Monogenic diabetes accounts for approximately 1-2% of diabetes cases and results from mutations that primarily reduce β-cell function. Individuals with islet autoantibody negative youth-onset forms of diabetes should be evaluated for either glucokinase-MODY or transcription factors MODY. The mild-fasting hyperglycemia found in glucokinase-MODY typically does not necessitate pharmacological treatment, whereas patients with MODY caused by transcription factor mutations can often be successfully treated with low-dose sulfonylurea. Neonatal diabetes is defined as diabetes onset within the first 6 months of life and most individuals with permanent neonatal diabetes can be treated with high-dose sulfonylurea. SUMMARY The discovery of the genetic cause of monogenic diabetes has greatly advanced our understanding and management of these uncommon forms of diabetes.
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Affiliation(s)
- Andrea K Steck
- Barbara Davis Center for Childhood Diabetes, University of Colorado Denver, Aurora, Colorado 80045-6511, USA
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Raile K, O'Connell M, Galler A, Werther G, Kühnen P, Krude H, Blankenstein O. Diabetes caused by insulin gene (INS) deletion: clinical characteristics of homozygous and heterozygous individuals. Eur J Endocrinol 2011; 165:255-60. [PMID: 21566073 DOI: 10.1530/eje-11-0208] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND Mutations of the preproinsulin gene (INS) account for both permanent neonatal diabetes (PND) and adult-onset diabetes. The molecular mechanism of complete INS deletion has recently been published and we now add clinical data of homozygous and heterozygous subjects as well as the detailed mapping of the 646 bp deletion of the INS gene. METHODS Location and size of the INS deletion was mapped in one case with PND and INS genotype of the whole family was further characterized by breakpoint-spanning PCR. The phenotype of monoallelic loss of INS was studied in 33 adult family members of a large consanguineous kindred with INS deletion. RESULTS The 646 bp deletion was found in two individuals with PND that included exons 1 and 2 of the INS gene (chr11: g.2138434_2139080del646) and results in loss of approximately half of the preproinsulin protein. The two boys with homozygous INS deletion (D/D) presented with reduced birth weight, PND within the first 24 h of life and complete absence of C-peptide. Adult family members with the N/D had diabetes onset with earliest 25 years, while the oldest subject without diabetes was 45 years. INS-deletion-diabetes was initially treated with oral antidiabetic drugs but then transferred to insulin within 5-16 years. Overall, N/D-subjects (n=11) had a higher risk to develop insulin-dependent diabetes up to the fifth decade, if compared with normal subjects (n=22). CONCLUSION Complete loss of the human INS gene results in neonatal diabetes, while heterozygous INS deletion is a strong risk factor for developing insulin-dependent diabetes at adult age.
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Affiliation(s)
- Klemens Raile
- Department of Pediatric Endocrinology and Diabetes, Charité Children's Hospital, Universitätsmedizin Berlin, Charité Campus Virchow, Augustenburger Platz 1, D-13353 Berlin, Germany.
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Molven A, Njølstad PR. Role of molecular genetics in transforming diagnosis of diabetes mellitus. Expert Rev Mol Diagn 2011; 11:313-20. [PMID: 21463240 DOI: 10.1586/erm.10.123] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Most common diseases also run in families as rare, monogenic forms. Diabetes is no exception. Mutations in approximately 20 different genes are now known to cause monogenic diabetes, a disease group that can be subclassified into maturity-onset diabetes of the young, neonatal diabetes and mitochondrial diabetes. In some families, additional features, such as urogenital malformations, exocrine pancreatic dysfunction and neurological abnormalities, are present and may aid the diagnostic classification. The finding of a mutation in monogenic diabetes may have implications for the prediction of prognosis and choice of treatment. Mutations in the GCK gene cause a mild form of diabetes, which seldom needs insulin and has a low risk for complications. By contrast, HNF1A mutations lead to a diabetes form that in severity, treatment and complication risk resembles Type 1 diabetes, although these patients may experience a good effect of sulfonylurea treatment. The majority of neonatal diabetes cases are caused by mutations in the K(ATP) channel genes ABCC8 and KCNJ11, and sulfonylurea therapy is then usually superior to insulin. Diseases with a considerable genetic component may now be explored by genome-wide approaches using next-generation DNA sequencing technology. We expect that within a few years important breakthroughs will be made in mapping cases of diabetes with a suspected, but still unsolved monogenic basis.
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Affiliation(s)
- Anders Molven
- The Gade Institute, University of Bergen, N-5020 Bergen, Norway
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Thomas SE, Dalton L, Malzer E, Marciniak SJ. Unravelling the story of protein misfolding in diabetes mellitus. World J Diabetes 2011; 2:114-8. [PMID: 21860696 PMCID: PMC3158865 DOI: 10.4239/wjd.v2.i7.114] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2011] [Revised: 06/30/2011] [Accepted: 07/07/2011] [Indexed: 02/05/2023] Open
Abstract
Both environmental and genetic factors contribute to the development of diabetes mellitus and although monogenic disorders are rare, they offer unique insights into the fundamental biology underlying the disease. Mutations of the insulin gene or genes involved in the response to protein misfolding cause early onset diabetes. These have revealed an important role for endoplasmic reticulum stress in β-cell survival. This form of cellular stress occurs when secretory proteins fail to fold efficiently. Of all the professional secretory cells we possess, β-cells are the most sensitive to endoplasmic reticulum stress because of the large fluctuations in protein synthesis they face daily. Studies of endoplasmic reticulum stress signaling therefore offer the potential to identify new drug targets to treat diabetes.
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Affiliation(s)
- Sally E Thomas
- Sally E Thomas, Lucy Dalton, Elke Malzer, Stefan J Marciniak, Department of Medicine, University of Cambridge, Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Hills Road, Cambridge CB0 2XY, United Kingdom
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Abstract
Neonatal diabetes mellitus (NDM) is the term commonly used to describe diabetes with onset before 6 months-of-age. It occurs in approximately one out of every 100,000-300,000 live births. Although this term encompasses diabetes of any etiology, it is recognized that NDM diagnosed before 6 months-of-age is most often monogenic in nature. Clinically, NDM subgroups include transient (TNDM) and permanent NDM (PNDM), as well as syndromic cases of NDM. TNDM often develops within the first few weeks of life and remits by a few months of age. However, relapse occurs in 50% of cases, typically in adolescence or adulthood. TNDM is most frequently caused by abnormalities in the imprinted region of chromosome 6q24, leading to overexpression of paternally derived genes. Mutations in KCNJ11 and ABCC8, encoding the two subunits of the adenosine triphosphate-sensitive potassium channel on the β-cell membrane, can cause TNDM, but more often result in PNDM. NDM as a result of mutations in KCNJ11 and ABCC8 often responds to sulfonylureas, allowing transition from insulin therapy. Mutations in other genes important to β-cell function and regulation, and in the insulin gene itself, also cause NDM. In 40% of NDM cases, the genetic cause remains unknown. Correctly identifying monogenic NDM has important implications for appropriate treatment, expected disease course and associated conditions, and genetic testing for at-risk family members. Early recognition of monogenic NDM allows for the implementation of appropriate therapy, leading to improved outcomes and potential societal cost savings. (J Diabetes Invest, doi:10.1111/j.2040-1124.2011.00106.x, 2011).
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Affiliation(s)
| | | | - Graeme I Bell
- Medicine, Section of Adult and Pediatric Endocrinology, Diabetes and Metabolism, The University of Chicago, Chicago, Illinois, USA
| | - Louis H Philipson
- Departments of Pediatrics
- Medicine, Section of Adult and Pediatric Endocrinology, Diabetes and Metabolism, The University of Chicago, Chicago, Illinois, USA
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65
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Quan Y, Barszczyk A, Feng ZP, Sun HS. Current understanding of K ATP channels in neonatal diseases: focus on insulin secretion disorders. Acta Pharmacol Sin 2011; 32:765-80. [PMID: 21602835 PMCID: PMC4009965 DOI: 10.1038/aps.2011.57] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2011] [Accepted: 04/13/2011] [Indexed: 12/25/2022] Open
Abstract
ATP-sensitive potassium (K(ATP)) channels are cell metabolic sensors that couple cell metabolic status to electric activity, thus regulating many cellular functions. In pancreatic beta cells, K(ATP) channels modulate insulin secretion in response to fluctuations in plasma glucose level, and play an important role in glucose homeostasis. Recent studies show that gain-of-function and loss-of-function mutations in K(ATP) channel subunits cause neonatal diabetes mellitus and congenital hyperinsulinism respectively. These findings lead to significant changes in the diagnosis and treatment for neonatal insulin secretion disorders. This review describes the physiological and pathophysiological functions of K(ATP) channels in glucose homeostasis, their specific roles in neonatal diabetes mellitus and congenital hyperinsulinism, as well as future perspectives of K(ATP) channels in neonatal diseases.
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Affiliation(s)
- Yi Quan
- Departments of Physiology, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada, M5S 1A8
| | - Andrew Barszczyk
- Departments of Physiology, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada, M5S 1A8
| | - Zhong-ping Feng
- Departments of Physiology, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada, M5S 1A8
| | - Hong-shuo Sun
- Departments of Physiology, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada, M5S 1A8
- Departments of Surgery, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada, M5S 1A8
- Departments of Pharmacology, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada, M5S 1A8
- Institute of Medical Science, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada, M5S 1A8
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66
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Bonnefond A, Lomberk G, Buttar N, Busiah K, Vaillant E, Lobbens S, Yengo L, Dechaume A, Mignot B, Simon A, Scharfmann R, Neve B, Tanyolaç S, Hodoglugil U, Pattou F, Cavé H, Iovanna J, Stein R, Polak M, Vaxillaire M, Froguel P, Urrutia R. Disruption of a novel Kruppel-like transcription factor p300-regulated pathway for insulin biosynthesis revealed by studies of the c.-331 INS mutation found in neonatal diabetes mellitus. J Biol Chem 2011; 286:28414-24. [PMID: 21592955 PMCID: PMC3151084 DOI: 10.1074/jbc.m110.215822] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Krüppel-like transcription factors (KLFs) have elicited significant attention because of their regulation of essential biochemical pathways and, more recently, because of their fundamental role in the mechanisms of human diseases. Neonatal diabetes mellitus is a monogenic disorder with primary alterations in insulin secretion. We here describe a key biochemical mechanism that underlies neonatal diabetes mellitus insulin biosynthesis impairment, namely a homozygous mutation within the insulin gene (INS) promoter, c.-331C>G, which affects a novel KLF-binding site. The combination of careful expression profiling, electromobility shift assays, reporter experiments, and chromatin immunoprecipitation demonstrates that, among 16 different KLF proteins tested, KLF11 is the most reliable activator of this site. Congruently, the c.-331C>G INS mutation fails to bind KLF11, thus inhibiting activation by this transcription factor. Klf11−/− mice recapitulate the disruption in insulin production and blood levels observed in patients. Thus, these data demonstrate an important role for KLF11 in the regulation of INS transcription via the novel c.-331 KLF site. Lastly, our screening data raised the possibility that other members of the KLF family may also regulate this promoter under distinct, yet unidentified, cellular contexts. Collectively, this study underscores a key role for KLF proteins in biochemical mechanisms of human diseases, in particular, early infancy onset diabetes mellitus.
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Affiliation(s)
- Amélie Bonnefond
- CNRS-UMR-8199, Lille Pasteur Institute, Lille Nord de France University, F-59800 Lille, France
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67
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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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68
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Pearl EJ, Jarikji Z, Horb ME. Functional analysis of Rfx6 and mutant variants associated with neonatal diabetes. Dev Biol 2011; 351:135-45. [PMID: 21215266 DOI: 10.1016/j.ydbio.2010.12.043] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Revised: 12/13/2010] [Accepted: 12/23/2010] [Indexed: 11/30/2022]
Abstract
Mutations in rfx6 were recently associated with Mitchell-Riley syndrome, which involves neonatal diabetes, and other digestive system defects. To better define the function of Rfx6 in early endoderm development we cloned the Xenopus homologue. Expression of rfx6 begins early, showing broad expression throughout the anterior endoderm; at later stages rfx6 expression becomes restricted to the endocrine cells of the gut and pancreas. Morpholino knockdown of rfx6 caused a loss of pancreas marker expression, as well as other abnormalities. Co-injection of exogenous wild-type rfx6 rescued the morpholino phenotype in Xenopus tadpoles, whereas attempts to rescue the loss-of-function phenotype using mutant rfx6 based on Mitchell-Riley patients were unsuccessful. To better define the pleiotropic effects, we performed microarray analyses of gene expression in knockdown foregut tissue. In addition to pancreatic defects, the microarray analyses revealed downregulation of lung, stomach and heart markers and an upregulation of kidney markers. We verified these results using RT-PCR and in situ hybridization. Based on the different rfx6 expression patterns and our functional analyses, we propose that rfx6 has both early and late functions. In early development Rfx6 plays a broad role, being essential for development of most anterior endodermal organs. At later stages however, Rfx6 function is restricted to endocrine cells.
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Affiliation(s)
- Esther J Pearl
- Laboratory of Molecular Organogenesis, Institut de recherches cliniques de Montréal, 110 avenue des Pins Ouest, Montreal, QC H2V4K1, Canada.
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69
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Aycan Z, Cetinkaya S, Oğuz SS, Ceylaner S. A new variant of a known mutation in two siblings with permanent neonatal diabetes mellitus. J Pediatr Endocrinol Metab 2011; 24:373-5. [PMID: 21823539 DOI: 10.1515/jpem.2011.187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Permanent neonatal diabetes mellitus is a rare disorder usually presenting within the first few weeks or months of life. This disorder is genetically heterogeneous and has been associated with mutations in various genes. The genetic cause remains mostly unknown although several genes have been linked to this disorder. Mutations in KCNJ11, ABCC8, or INS are the cause of permanent neonatal diabetes mellitus in about 50%-60% of the patients. With genetic studies, we hope to increase our knowledge of neonatal diabetes, whereby new treatment models can become possible. Here, we defined a new variant of a known mutation, INS Exon 1-3 homozygous deletion, in two siblings diagnosed with permanent neonatal diabetes mellitus.
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Affiliation(s)
- Zehra Aycan
- Dr Sami Ulus Obstetrics and Gynecology, Children's Health and Disease Training and Research Hospital, Ankara, Turkey
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70
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Liu M, Hodish I, Haataja L, Lara-Lemus R, Rajpal G, Wright J, Arvan P. Proinsulin misfolding and diabetes: mutant INS gene-induced diabetes of youth. Trends Endocrinol Metab 2010; 21:652-9. [PMID: 20724178 PMCID: PMC2967602 DOI: 10.1016/j.tem.2010.07.001] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2010] [Revised: 07/07/2010] [Accepted: 07/08/2010] [Indexed: 12/23/2022]
Abstract
Type 1B diabetes (typically with early onset and without islet autoantibodies) has been described in patients bearing small coding sequence mutations in the INS gene. Not all mutations in the INS gene cause the autosomal dominant Mutant INS-gene Induced Diabetes of Youth (MIDY) syndrome, but most missense mutations affecting proinsulin folding produce MIDY. MIDY patients are heterozygotes, with the expressed mutant proinsulins exerting dominant-negative (toxic gain of function) behavior in pancreatic beta cells. Here we focus primarily on proinsulin folding in the endoplasmic reticulum, providing insight into perturbations of this folding pathway in MIDY. Accumulated evidence indicates that, in the molecular pathogenesis of the disease, misfolded proinsulin exerts dominant effects that initially inhibit insulin production, progressing to beta cell demise with diabetes.
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Affiliation(s)
| | | | | | | | | | | | - Peter Arvan
- To whom correspondence may be addressed: Division of Metabolism, Endocrinology & Diabetes University of Michigan, 5560 MSRB2 1150 W. Medical Center Drive Ann Arbor, MI 48109-0678 Telephone: 734-936-5006 FAX: 734-936-6684
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71
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Bonnefond A, Durand E, Sand O, De Graeve F, Gallina S, Busiah K, Lobbens S, Simon A, Bellanné-Chantelot C, Létourneau L, Scharfmann R, Delplanque J, Sladek R, Polak M, Vaxillaire M, Froguel P. Molecular diagnosis of neonatal diabetes mellitus using next-generation sequencing of the whole exome. PLoS One 2010; 5:e13630. [PMID: 21049026 PMCID: PMC2964316 DOI: 10.1371/journal.pone.0013630] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2010] [Accepted: 09/30/2010] [Indexed: 11/18/2022] Open
Abstract
Background Accurate molecular diagnosis of monogenic non-autoimmune neonatal diabetes mellitus (NDM) is critical for patient care, as patients carrying a mutation in KCNJ11 or ABCC8 can be treated by oral sulfonylurea drugs instead of insulin therapy. This diagnosis is currently based on Sanger sequencing of at least 42 PCR fragments from the KCNJ11, ABCC8, and INS genes. Here, we assessed the feasibility of using the next-generation whole exome sequencing (WES) for the NDM molecular diagnosis. Methodology/Principal Findings We carried out WES for a patient presenting with permanent NDM, for whom mutations in KCNJ11, ABCC8 and INS and abnormalities in chromosome 6q24 had been previously excluded. A solution hybridization selection was performed to generate WES in 76 bp paired-end reads, by using two channels of the sequencing instrument. WES quality was assessed using a high-resolution oligonucleotide whole-genome genotyping array. From our WES with high-quality reads, we identified a novel non-synonymous mutation in ABCC8 (c.1455G>C/p.Q485H), despite a previous negative sequencing of this gene. This mutation, confirmed by Sanger sequencing, was not present in 348 controls and in the patient's mother, father and young brother, all of whom are normoglycemic. Conclusions/Significance WES identified a novel de novo ABCC8 mutation in a NDM patient. Compared to the current Sanger protocol, WES is a comprehensive, cost-efficient and rapid method to identify mutations in NDM patients. We suggest WES as a near future tool of choice for further molecular diagnosis of NDM cases, negative for chr6q24, KCNJ11 and INS abnormalities.
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Affiliation(s)
| | | | - Olivier Sand
- CNRS-UMR-8199, Univ Lille Nord de France, UDSL, Lille, France
| | | | - Sophie Gallina
- CNRS-UMR-8199, Univ Lille Nord de France, UDSL, Lille, France
| | - Kanetee Busiah
- Inserm-U845, Department of Pediatric Endocrinology, Necker Enfants Malades Hospital, Université Paris Descartes, Paris, France
| | | | - Albane Simon
- Inserm-U845, Department of Pediatric Endocrinology, Necker Enfants Malades Hospital, Université Paris Descartes, Paris, France
| | | | - Louis Létourneau
- Department of Human Genetics, Faculty of Medicine, McGill University, Montreal, and Genome Quebec Innovation Centre, Montreal, Canada
| | - Raphael Scharfmann
- Inserm-U845, Department of Pediatric Endocrinology, Necker Enfants Malades Hospital, Université Paris Descartes, Paris, France
| | | | - Robert Sladek
- Department of Human Genetics, Faculty of Medicine, McGill University, Montreal, and Genome Quebec Innovation Centre, Montreal, Canada
| | - Michel Polak
- Inserm-U845, Department of Pediatric Endocrinology, Necker Enfants Malades Hospital, Université Paris Descartes, Paris, France
| | | | - Philippe Froguel
- CNRS-UMR-8199, Univ Lille Nord de France, UDSL, Lille, France
- Department of Genomics of Common Disease, School of Public Health, Imperial College London, Hammersmith Hospital, London, United Kingdom
- * E-mail:
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72
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Liu M, Haataja L, Wright J, Wickramasinghe NP, Hua QX, Phillips NF, Barbetti F, Weiss MA, Arvan P. Mutant INS-gene induced diabetes of youth: proinsulin cysteine residues impose dominant-negative inhibition on wild-type proinsulin transport. PLoS One 2010; 5:e13333. [PMID: 20948967 PMCID: PMC2952628 DOI: 10.1371/journal.pone.0013333] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2010] [Accepted: 09/13/2010] [Indexed: 02/06/2023] Open
Abstract
Recently, a syndrome of Mutant INS-gene-induced Diabetes of Youth (MIDY, derived from one of 26 distinct mutations) has been identified as a cause of insulin-deficient diabetes, resulting from expression of a misfolded mutant proinsulin protein in the endoplasmic reticulum (ER) of insulin-producing pancreatic beta cells. Genetic deletion of one, two, or even three alleles encoding insulin in mice does not necessarily lead to diabetes. Yet MIDY patients are INS-gene heterozygotes; inheritance of even one MIDY allele, causes diabetes. Although a favored explanation for the onset of diabetes is that insurmountable ER stress and ER stress response from the mutant proinsulin causes a net loss of beta cells, in this report we present three surprising and interlinked discoveries. First, in the presence of MIDY mutants, an increased fraction of wild-type proinsulin becomes recruited into nonnative disulfide-linked protein complexes. Second, regardless of whether MIDY mutations result in the loss, or creation, of an extra unpaired cysteine within proinsulin, Cys residues in the mutant protein are nevertheless essential in causing intracellular entrapment of co-expressed wild-type proinsulin, blocking insulin production. Third, while each of the MIDY mutants induces ER stress and ER stress response; ER stress and ER stress response alone appear insufficient to account for blockade of wild-type proinsulin. While there is general agreement that ultimately, as diabetes progresses, a significant loss of beta cell mass occurs, the early events described herein precede cell death and loss of beta cell mass. We conclude that the molecular pathogenesis of MIDY is initiated by perturbation of the disulfide-coupled folding pathway of wild-type proinsulin.
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Affiliation(s)
- Ming Liu
- Division of Metabolism, Endocrinology and Diabetes, University of Michigan Medical Center, Ann Arbor, Michigan, United States of America
| | - Leena Haataja
- Division of Metabolism, Endocrinology and Diabetes, University of Michigan Medical Center, Ann Arbor, Michigan, United States of America
| | - Jordan Wright
- Division of Metabolism, Endocrinology and Diabetes, University of Michigan Medical Center, Ann Arbor, Michigan, United States of America
| | - Nalinda P. Wickramasinghe
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Qing-Xin Hua
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Nelson F. Phillips
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Fabrizio Barbetti
- Laboratory of Molecular Endocrinology and Metabolism, Bambino Gesù Children's Hospital, Scientific Institute (IRCCS), Rome, Italy
- Department of Internal Medicine, University of Tor Vergata, Rome, Italy
| | - Michael A. Weiss
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio, United States of America
- * E-mail: (PA); (MAW)
| | - Peter Arvan
- Division of Metabolism, Endocrinology and Diabetes, University of Michigan Medical Center, Ann Arbor, Michigan, United States of America
- * E-mail: (PA); (MAW)
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73
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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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74
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Abstract
The elucidation of several genetic etiologies of both monogenic and polygenic type 2 diabetes (T2D) has revealed several key regulators of glucose homeostasis and insulin secretion in humans. Genome-wide association studies (GWAS) have been instrumental in most of these recent discoveries. The T2D susceptibility genes identified so far are mainly involved in pancreatic beta-cell maturation or function. However, common DNA variants in those genes only explain approximately 10% of T2D heritability. The resequencing of whole exomes and whole genomes with next-generation technologies should identify additional genetic changes that contribute to the monogenic forms of diabetes and possibly provide novel clues to the genetic architecture of common adult T2D.
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75
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Greeley SAW, Tucker SE, Naylor RN, Bell GI, Philipson LH. Neonatal diabetes mellitus: a model for personalized medicine. Trends Endocrinol Metab 2010; 21:464-72. [PMID: 20434356 PMCID: PMC2914172 DOI: 10.1016/j.tem.2010.03.004] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2009] [Revised: 03/19/2010] [Accepted: 03/19/2010] [Indexed: 01/30/2023]
Abstract
Neonatal diabetes mellitus occurs in approximately 1 out of every 100,000 live births. It can be either permanent or transient, and recent studies indicate that is likely to have an underlying genetic cause, particularly when diagnosed before 6 months of age. Permanent neonatal diabetes is most commonly due to activating mutations in either of the genes encoding the two subunits of the ATP-sensitive potassium channel. In most of these patients, switching from insulin to oral sulfonylurea therapy leads to improved metabolic control, as well as possible amelioration of occasional associated neurodevelopmental disabilities. It remains to be determined what is the most appropriate treatment of other causes. The diagnosis and treatment of neonatal diabetes, therefore, represents a model for personalized medicine.
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Affiliation(s)
- Siri Atma W Greeley
- Department of Pediatrics, Section of Adult and Pediatric Endocrinology, Diabetes and Metabolism, University of Chicago Pritzker School of Medicine, 5841 S Maryland Ave, MC 1027, Chicago, IL 60637, USA.
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76
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Ben Hamouda H, Chioukh F, Boussetta B, Mahjoub B, Ayadi A, Belkhir Y, Boussoffara R, Soua H, Sfar MT. [Long-term follow-up of permanent neonatal diabetes in Tunisian infant]. ANNALES D'ENDOCRINOLOGIE 2010; 71:314-9. [PMID: 20554266 DOI: 10.1016/j.ando.2009.12.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2009] [Revised: 12/01/2009] [Accepted: 12/28/2009] [Indexed: 10/19/2022]
Abstract
Neonatal diabetes mellitus is a rare entity defined as hyperglycaemia occurring within the first 3 months of life that lasts for at least 2 weeks and requiring insulin therapy for unforeseeable duration. We report the case of a full-term female infant with permanent neonatal diabetes mellitus, stemming from consanguineous parents, born with severe intra-uterine growth retardation and birth weight of 1400 g. The patient presented on the 15th day of life a severe dehydration with a fever and ponderal loss of 14 %. The biology showed hyperglycaemia to 15 mmol/L, moderate metabolic acidosis, glucosuria and ketonuria. The diagnosis of neonatal diabetes mellitus was reserved, justifying its stake under insulin. Etiologic investigation showed a type HLA-DR4/DR8; anti-insulin antibodies were weakly positive, Langerhans islet cell and anti-GAD antibodies were negative. Abdominal magnetic resonance imaging scans, karyotype, molecular biology and chromatography of amino and organic acids did not show any abnormalities. During the first 2 years of age, the patient presented a big instability of glycaemia having required several hospitalizations. After 12 years of age, the patient is still under insulin with a satisfactory glycaemia balance and her growth is normal. Besides, she presents a microcephaly with a spastic walking. The search of neonatal diabetes mellitus must be systematic in front of any fetal hypotrophy allowing a premature coverage and a good prognosis.
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Affiliation(s)
- H Ben Hamouda
- Unité de néonatalogie, service de pédiatrie, hôpital universitaire Tahar Sfar, 5111 Mahdia, Tunisie.
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77
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Vasanwala R, Yap F, Lim SH, Lim PK, Lim ST, Hui A. Identification of First Case of Neonatal Diabetes in Singapore and Successful Conversion from Insulin to Sulphonylurea. PROCEEDINGS OF SINGAPORE HEALTHCARE 2010. [DOI: 10.1177/201010581001900205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Introduction: To date Neonatal Diabetes Mellitus (NDM) has not been reported in Singapore. Neonatal diabetes is a rare (1 in 100,00–300,000 live births) insulin-requiring form of diabetes with well defined subgroups, permanent neonatal diabetes (PND) and transient neonatal diabetes (TND), each accounting for approximately 50% of patients. Genotyping NDM identifies the exact unique molecular aetiology of very early onset insulin requiring diabetes and has the potential to dramatically alter the management of the patient, who would otherwise be insulin dependent for life. Method: We identified a child who presented at 3 and half months of age with diabetic ketoacidosis and determined the phenotypic and genotypic characteristics. Blood samples for molecular genetic analysis were sent to Royal Devon and Exeter Foundation Trust, UK. We determined her Continuous Glucose Monitoring profiles after initiation of sulphonylurea therapy. Results: The patient was diagnosed as a heterozygous for a missense mutation R201H, in the KCNJ11 gene. Results confirmed a diagnosis of permanent neonatal diabetes due to a mutation in the Kir6.2 subunit of the KATP channel. We initiated sulphonylurea therapy and subsequently ceased insulin treatment successfully. Currently 2 years old, this patient is no longer insulin dependent. Conclusion: This is the first case report of neonatal diabetes in Singapore. It describes the importance of correct identification of the case, and successful conversion of therapy from insulin to sulphonylureas with optimal blood glucose control. We emphasise the need for medical practitioners to consider molecular testing for all patients who present with diabetes below 6 months of age as this will facilitate accurate diagnosis and appropriate therapy.
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Affiliation(s)
- Rashida Vasanwala
- Department of Paediatric Medicine, KK Women's and Children's Hospital, Singapore
| | - Fabian Yap
- Department of Paediatric Medicine, KK Women's and Children's Hospital, Singapore
| | - Song Hai Lim
- Department of Paediatric Medicine, KK Women's and Children's Hospital, Singapore
| | - Pei Kwee Lim
- Department of Paediatric Medicine, KK Women's and Children's Hospital, Singapore
| | - Soo Ting Lim
- Department of Paediatric Medicine, KK Women's and Children's Hospital, Singapore
| | - Angela Hui
- Department of Paediatric Medicine, KK Women's and Children's Hospital, Singapore
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78
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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: 106] [Impact Index Per Article: 7.6] [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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79
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Rajan S, Eames SC, Park SY, Labno C, Bell GI, Prince VE, Philipson LH. In vitro processing and secretion of mutant insulin proteins that cause permanent neonatal diabetes. Am J Physiol Endocrinol Metab 2010; 298:E403-10. [PMID: 19952343 PMCID: PMC2838531 DOI: 10.1152/ajpendo.00592.2009] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Permanent neonatal diabetes mellitus is a rare form of insulin-requiring diabetes presenting within the first few weeks or months of life. Mutations in the insulin gene are the second most common cause of this form of diabetes. These mutations are located in critical regions of preproinsulin and are likely to prevent normal processing or folding of the preproinsulin/proinsulin molecule. To characterize these mutations, we transiently expressed proinsulin-GFP fusion proteins in MIN6 mouse insulinoma cells. Our study revealed three groups of mutant proteins: 1) mutations that result in retention of proinsulin in the endoplasmic reticulum (ER) and attenuation of secretion of cotransfected wild-type insulin: C43G, F48C, and C96Y; 2) mutations with partial ER retention, partial recruitment to granules, and attenuation of secretion of wild-type insulin: G32R, G32S, G47V, G90C, and Y108C; and 3) similar to (2) but with no significant attenuation of wild-type insulin secretion: A24D and R89C. The mutant insulin proteins do not prevent targeting of wild-type insulin to secretory granules, but most appear to lead to decreased secretion of wild-type insulin. Each of the mutants triggers the expression of the proapoptotic gene Chop, indicating the presence of ER stress.
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Affiliation(s)
- Sindhu Rajan
- Department of Medicine, Univ. of Chicago, IL 60637, USA
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80
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Abstract
PURPOSE OF REVIEW Here we give context to new data on neonatal diabetes mellitus, a rare group of insulin-requiring monogenic forms of diabetes presenting at birth or shortly thereafter. Genetic studies are critical in the diagnosis and treatment of these patients. The most common causes of neonatal diabetes are activating mutations in the two protein subunits of the ATP-sensitive potassium channel. These are responsible for about half of all cases of permanent neonatal diabetes and some cases of transient neonatal diabetes. Identification of these mutations allows patients treated with insulin to be transferred to sulfonylureas, but associated conditions and other causes must be considered. RECENT FINDINGS Recent data suggest that neonatal diabetes is more common than previously thought, with variable presentations. Continued studies provide further evidence for amelioration of developmental and neurological dysfunction exhibited by a significant proportion of patients. Abnormalities of chromosome 6q24 remain the most common cause of transient neonatal diabetes. Other causes of neonatal diabetes being studied include mutations in proinsulin, FOXP3 mutations in immunodysregulation, polyendocrinopathy, enteropathy, X-linked syndrome, homozygous glucokinase mutations, and Wolcott-Rallinson/EIF2AK3 diabetes. SUMMARY We still have much to learn about the different forms of neonatal diabetes, their associated clinical features, and the optimization of therapy using a growing number of available therapeutic agents.
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Affiliation(s)
- Siri Atma W Greeley
- Department of Medicine, The University of Chicago, Chicago, Illinois 60637, USA
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81
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Recessive mutations in the INS gene result in neonatal diabetes through reduced insulin biosynthesis. Proc Natl Acad Sci U S A 2010; 107:3105-10. [PMID: 20133622 DOI: 10.1073/pnas.0910533107] [Citation(s) in RCA: 145] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Heterozygous coding mutations in the INS gene that encodes preproinsulin were recently shown to be an important cause of permanent neonatal diabetes. These dominantly acting mutations prevent normal folding of proinsulin, which leads to beta-cell death through endoplasmic reticulum stress and apoptosis. We now report 10 different recessive INS mutations in 15 probands with neonatal diabetes. Functional studies showed that recessive mutations resulted in diabetes because of decreased insulin biosynthesis through distinct mechanisms, including gene deletion, lack of the translation initiation signal, and altered mRNA stability because of the disruption of a polyadenylation signal. A subset of recessive mutations caused abnormal INS transcription, including the deletion of the C1 and E1 cis regulatory elements, or three different single base-pair substitutions in a CC dinucleotide sequence located between E1 and A1 elements. In keeping with an earlier and more severe beta-cell defect, patients with recessive INS mutations had a lower birth weight (-3.2 SD score vs. -2.0 SD score) and were diagnosed earlier (median 1 week vs. 10 weeks) compared to those with dominant INS mutations. Mutations in the insulin gene can therefore result in neonatal diabetes as a result of two contrasting pathogenic mechanisms. Moreover, the recessively inherited mutations provide a genetic demonstration of the essential role of multiple sequence elements that regulate the biosynthesis of insulin in man.
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82
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Park SY, Ye H, Steiner DF, Bell GI. Mutant proinsulin proteins associated with neonatal diabetes are retained in the endoplasmic reticulum and not efficiently secreted. Biochem Biophys Res Commun 2009; 391:1449-54. [PMID: 20034470 DOI: 10.1016/j.bbrc.2009.12.090] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2009] [Accepted: 12/16/2009] [Indexed: 11/17/2022]
Abstract
Mutations in the preproinsulin protein that affect processing of preproinsulin to proinsulin or lead to misfolding of proinsulin are associated with diabetes. We examined the subcellular localization and secretion of 13 neonatal diabetes-associated human proinsulin proteins (A24D, G32R, G32S, L35P, C43G, G47V, F48C, G84R, R89C, G90C, C96Y, S101C and Y108C) in rat INS-1 insulinoma cells. These mutant proinsulin proteins accumulate in the endoplasmic reticulum (ER) and are poorly secreted except for G84R and in contrast to wild-type and hyperproinsulinemia-associated mutant proteins (H34D and R89H) which were sorted to secretory granules and efficiently secreted. We also examined the effect of C96Y mutant proinsulin on the synthesis and secretion of wild-type insulin and observed a dominant-negative effect of the mutant proinsulin on the synthesis and secretion of wild-type insulin due to induction of the unfolded protein response and resulting attenuation of overall translation.
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Affiliation(s)
- Soo-Young Park
- Department of Medicine, The University of Chicago, 5841 S. Maryland Avenue, MC 1027, Chicago, IL 60637, USA.
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83
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Vaxillaire M, Froguel P. Monogenic forms of diabetes mellitus: an update. ENDOCRINOLOGIA Y NUTRICION : ORGANO DE LA SOCIEDAD ESPANOLA DE ENDOCRINOLOGIA Y NUTRICION 2009; 56S4:26-29. [PMID: 20542223 DOI: 10.1016/s1575-0922(09)73513-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Martine Vaxillaire
- Genomics and Molecular Physiology of Metabolic Diseases. CNRS UMR8090. Lille Institute of Biology. Lille. France
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84
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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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85
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Hodish I, Liu M, Rajpal G, Larkin D, Holz RW, Adams A, Liu L, Arvan P. Misfolded proinsulin affects bystander proinsulin in neonatal diabetes. J Biol Chem 2009; 285:685-94. [PMID: 19880509 DOI: 10.1074/jbc.m109.038042] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
It has previously been shown that misfolded mutant Akita proinsulin in the endoplasmic reticulum engages directly in protein complexes either with nonmutant proinsulin or with "hProCpepGFP" (human proinsulin bearing emerald-GFP within the C-peptide), impairing the trafficking of these "bystander" proinsulin molecules (Liu, M., Hodish, I., Rhodes, C. J., and Arvan, P. (2007) Proc. Natl. Acad. Sci. U.S.A. 104, 15841-15846). Herein, we generated transgenic mice, which, in addition to expressing endogenous proinsulin, exhibit beta-cell-specific expression of hProCpepGFP via the Ins1 promoter. In these mice, hProCpepGFP protein levels are physiologically regulated, and hProCpepGFP is packaged and processed to CpepGFP that is co-stored in beta-secretory granules. Visualization of CpepGFP fluorescence provides a quantifiable measure of pancreatic islet insulin content that can be followed in live animals in states of health and disease. We examined loss of pancreatic insulin in hProCpepGFP transgenic mice mated to Akita mice that develop neonatal diabetes because of the expression of misfolded proinsulin. Loss of bystander insulin in Akita animals is detected initially as a block in CpepGFP/insulin production with intracellular accumulation of the precursor, followed ultimately by loss of pancreatic beta-cells. The data support that misfolded proinsulin perturbs bystander proinsulin in the endoplasmic reticulum, leading to beta-cell failure.
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Affiliation(s)
- Israel Hodish
- Division of Metabolism, Endocrinology, and Diabetes, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0678, USA
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86
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Rubio-Cabezas O, Edghill EL, Argente J, Hattersley AT. Testing for monogenic diabetes among children and adolescents with antibody-negative clinically defined Type 1 diabetes. Diabet Med 2009; 26:1070-4. [PMID: 19900242 DOI: 10.1111/j.1464-5491.2009.02812.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
AIMS Monogenic diabetes is frequently misdiagnosed as Type 1 diabetes. We aimed to screen for undiagnosed monogenic diabetes in a cohort of children who had a clinical diagnosis of Type 1 diabetes but were pancreatic autoantibody-negative. METHODS We studied 252 patients diagnosed clinically with Type 1 diabetes between 6 months and 17 years of age. Pancreatic autoantibodies [islet cell autoantibodies (ICA), glutamic acid decarboxylase antibodies (GADA) and/or insulinoma-associated antigen-2 antibodies (IA2A)] were absent in 25 cases (9.9%). The most frequent genes involved in monogenic diabetes [KCNJ11 and INS for neonatal diabetes and HNF1A and HNF4A for maturity-onset diabetes of the young (MODY)] were directly sequenced. RESULTS Two of the 25 (8%) antibody-negative patients had de novo heterozygous mutations in INS; c.94G>A (G32S) and c.265C>T (R89C). The two patients presented with non-ketotic hyperglycaemia at 8 and 11 months of age. In contrast, the four antibody-positive patients who presented at a similar age (6-12 months) had a more severe metabolic derangement, manifested as ketosis in all four cases, with ketoacidosis in two. At ages 15 and 5 years, both INS mutation patients were prescribed a replacement dose of insulin with good glycaemic control [glycated haemoglobin (HbA(1c)) 7.0 and 7.2%]. No mutations were found in KCNJ11, HNF1A or HNF4A. CONCLUSIONS The identification of patients with monogenic diabetes from children with clinically defined Type 1 diabetes may be helped by clinical criteria including the absence of pancreatic autoantibodies.
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Affiliation(s)
- O Rubio-Cabezas
- Department of Endocrinology, Hospital Infantil Universitario Niño Jesús, Madrid, Spain.
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87
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Abstract
Crystal structures of insulin are remarkable for a long-range reorganization among three families of hexamers (designated T(6), T(3)R(3)(f), and R(6)). Although these structures are well characterized at atomic resolution, the biological implications of the TR transition remain the subject of speculation. Recent studies indicate that such allostery reflects a structural switch between distinct folding-competent and active conformations. Stereospecific modulation of this switch by corresponding d- and l-amino-acid substitutions yields reciprocal effects on protein stability and receptor-binding activity. Naturally occurring human mutations at the site of conformational change impair the folding of proinsulin and cause permanent neonatal-onset diabetes mellitus. The repertoire of classical structures thus foreshadows the conformational lifecycle of insulin in vivo. By highlighting the richness of information provided by protein crystallography-even in a biological realm far removed from conditions of crystallization-these findings validate the prescient insights of the late D. C. Hodgkin. Future studies of the receptor-bound structure of insulin may enable design of novel agonists for the treatment of diabetes mellitus.
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88
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Malecki MT, Mlynarski W, Skupien J. Can geneticists help clinicians to understand and treat non-autoimmune diabetes? Diabetes Res Clin Pract 2008; 82 Suppl 2:S83-93. [PMID: 19010562 DOI: 10.1016/j.diabres.2008.09.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Approximately, a few percent of the European population suffers from diabetes. Scientific evidence showed that specific treatment of this disease could be successfully tailored on the basis of proper differential diagnosis that in many instances also requires genetic testing. This may be helpful in achieving metabolic control of the disease, increasing quality of life and potentially reducing the prevalence of chronic complications. Identification of the molecular background of these specific forms of diabetes gives new insight into the underlying aetiology. This knowledge helps to optimize treatment in specific clinical situations. Monogenic diabetes is an excellent example of a clinical area where new advances in molecular genetics can aid patient care and treatment decisions. The most frequently diagnosed forms of monogenic diabetes are MODY, mitochondrial diabetes, permanent and transient neonatal diabetes (PNDM and TNDM). These rare forms probably constitute at least a few percent of all diabetes cases seen in diabetic clinics. The proper differential diagnosis also helps to predict the progress of diabetes in affected individuals and defines the prognosis in the family. Recently, several genome wide association studies added new facts to the knowledge on complex forms of type 2 diabetes mellitus (T2DM) as the scientists substantially extended the short list of previously identified genes. Most newly identified variants influence beta-cell insulin secretion, while a few modulate peripheral insulin action. It is not clear whether in the future the genetic testing of frequent polymorphisms will influence the treatment of T2DM. In this review, we present the clinical application of genetic testing in non-autoimmune diabetes, mostly monogenic forms of disease.
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Affiliation(s)
- Maciej T Malecki
- Department of Metabolic Diseases, Jagiellonian University, Medical College, 15 Kopernika Street, 31-501 Krakow, Poland.
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89
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Støy J, Greeley SAW, Paz VP, Ye H, Pastore AN, Skowron KB, Lipton RB, Cogen FR, Bell GI, Philipson LH. Diagnosis and treatment of neonatal diabetes: a United States experience. Pediatr Diabetes 2008; 9:450-9. [PMID: 18662362 PMCID: PMC2574846 DOI: 10.1111/j.1399-5448.2008.00433.x] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND/OBJECTIVE Mutations in KCNJ11, ABCC8, or INS are the cause of permanent neonatal diabetes mellitus in about 50% of patients diagnosed with diabetes before 6 months of age and in a small fraction of those diagnosed between 6 and 12 months. The aim of this study was to identify the genetic cause of diabetes in 77 consecutive patients referred to the University of Chicago with diabetes diagnosed before 1 yr of age. METHODS We used Oragene DNA Self-Collection kit to obtain a saliva sample for DNA. We sequenced the protein-coding regions of KCNJ11, ABCC8, and INS using standard methods. RESULTS We enrolled 32 patients diagnosed with diabetes before 6 months of age and 45 patients diagnosed between 6 and 12 months. We identified a mutation in KCNJ11 in 14 patients from 12 families and in INS in 7 patients from 4 families. Three of the patients with an INS mutation were diagnosed with diabetes between 6 and 12 months of age. Finally, we found that two patients had an abnormality of chromosome 6q24 associated with transient neonatal diabetes mellitus. CONCLUSIONS We were able to establish a genetic cause of diabetes in 63% of patients diagnosed with diabetes before 6 months of age and in 7% of patients diagnosed between 6 and 12 months. Genetic testing, which is critical for guiding appropriate management, should be considered in patients diagnosed with diabetes before 1 yr of age, especially if they are autoantibody negative, although the presence of autoantibodies does not rule out a monogenic cause.
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Affiliation(s)
- Julie Støy
- Department of Medicine, The University of Chicago, Chicago, IL 60637, USA
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90
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Abstract
The UPR (unfolded protein response) or ER (endoplasmic reticulum) stress response was first described 20 years ago. The field of ER stress has expanded tremendously since, moving from basic biology in yeast to human neurodegenerative, inflammatory, cardiovascular and neoplastic diseases. The ER stress response has also been implicated in diabetes development, affecting both insulin production by pancreatic β-cells and insulin sensitivity in peripheral tissues. In the present mini-review, we focus on recent progress in the field of ER stress in pancreatic β-cells. Recent advances in the understanding of lipotoxic ER stress and β-cell recovery from ER stress are discussed.
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91
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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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92
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Abstract
An explosion of work over the last decade has produced insight into the multiple hereditary causes of a nonimmunological form of diabetes diagnosed most frequently within the first 6 months of life. These studies are providing increased understanding of genes involved in the entire chain of steps that control glucose homeostasis. Neonatal diabetes is now understood to arise from mutations in genes that play critical roles in the development of the pancreas, of beta-cell apoptosis and insulin processing, as well as the regulation of insulin release. For the basic researcher, this work is providing novel tools to explore fundamental molecular and cellular processes. For the clinician, these studies underscore the need to identify the genetic cause underlying each case. It is increasingly clear that the prognosis, therapeutic approach, and genetic counseling a physician provides must be tailored to a specific gene in order to provide the best medical care.
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Affiliation(s)
- Lydia Aguilar-Bryan
- Pacific Northwest Diabetes Research Institute, 720 Broadway, Seattle, Washington 98122, USA.
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93
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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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