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Elangeeb ME, Elfaki I, Eleragi AMS, Ahmed EM, Mir R, Alzahrani SM, Bedaiwi RI, Alharbi ZM, Mir MM, Ajmal MR, Tayeb FJ, Barnawi J. Molecular Dynamics Simulation of Kir6.2 Variants Reveals Potential Association with Diabetes Mellitus. Molecules 2024; 29:1904. [PMID: 38675722 PMCID: PMC11054064 DOI: 10.3390/molecules29081904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2024] [Revised: 04/13/2024] [Accepted: 04/18/2024] [Indexed: 04/28/2024] Open
Abstract
Diabetes mellitus (DM) represents a problem for the healthcare system worldwide. DM has very serious complications such as blindness, kidney failure, and cardiovascular disease. In addition to the very bad socioeconomic impacts, it influences patients and their families and communities. The global costs of DM and its complications are huge and expected to rise by the year 2030. DM is caused by genetic and environmental risk factors. Genetic testing will aid in early diagnosis and identification of susceptible individuals or populations using ATP-sensitive potassium (KATP) channels present in different tissues such as the pancreas, myocardium, myocytes, and nervous tissues. The channels respond to different concentrations of blood sugar, stimulation by hormones, or ischemic conditions. In pancreatic cells, they regulate the secretion of insulin and glucagon. Mutations in the KCNJ11 gene that encodes the Kir6.2 protein (a major constituent of KATP channels) were reported to be associated with Type 2 DM, neonatal diabetes mellitus (NDM), and maturity-onset diabetes of the young (MODY). Kir6.2 harbors binding sites for ATP and phosphatidylinositol 4,5-diphosphate (PIP2). The ATP inhibits the KATP channel, while the (PIP2) activates it. A Kir6.2 mutation at tyrosine330 (Y330) was demonstrated to reduce ATP inhibition and predisposes to NDM. In this study, we examined the effect of mutations on the Kir6.2 structure using bioinformatics tools and molecular dynamic simulations (SIFT, PolyPhen, SNAP2, PANTHER, PhD&SNP, SNP&Go, I-Mutant, MuPro, MutPred, ConSurf, HOPE, and GROMACS). Our results indicated that M199R, R201H, R206H, and Y330H mutations influence Kir6.2 structure and function and therefore may cause DM. We conclude that MD simulations are useful techniques to predict the effects of mutations on protein structure. In addition, the M199R, R201H, R206H, and Y330H variant in the Kir6.2 protein may be associated with DM. These results require further verification in protein-protein interactions, Kir6.2 function, and case-control studies.
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Affiliation(s)
- Mohamed E. Elangeeb
- Department of Basic Medical Sciences, College of Applied Medical Sciences, University of Bisha, Bisha 61922, Saudi Arabia
| | - Imadeldin Elfaki
- Department of Biochemistry, Faculty of Science, University of Tabuk, Tabuk 71491, Saudi Arabia; (S.M.A.); (M.R.A.)
| | - Ali M. S. Eleragi
- Department of Microbiology, College of Medicine, University of Bisha, Bisha 61922, Saudi Arabia;
| | - Elsadig Mohamed Ahmed
- Department of Medical Laboratory Sciences, College of Applied Medical Sciences, University of Bisha, Bisha 61922, Saudi Arabia;
- Department of Clinical Chemistry, Faculty of Medical Laboratory Sciences, University of El Imam El Mahdi, Kosti 27711, Sudan
| | - Rashid Mir
- Department of Medical Laboratory Technology, Prince Fahad Bin Sultan Chair for Biomedical Research, Faculty of Applied Medical Sciences, University of Tabuk, Tabuk 71491, Saudi Arabia; (R.M.); (R.I.B.); (Z.M.A.); (F.J.T.); (J.B.)
| | - Salem M. Alzahrani
- Department of Biochemistry, Faculty of Science, University of Tabuk, Tabuk 71491, Saudi Arabia; (S.M.A.); (M.R.A.)
| | - Ruqaiah I. Bedaiwi
- Department of Medical Laboratory Technology, Prince Fahad Bin Sultan Chair for Biomedical Research, Faculty of Applied Medical Sciences, University of Tabuk, Tabuk 71491, Saudi Arabia; (R.M.); (R.I.B.); (Z.M.A.); (F.J.T.); (J.B.)
| | - Zeyad M. Alharbi
- Department of Medical Laboratory Technology, Prince Fahad Bin Sultan Chair for Biomedical Research, Faculty of Applied Medical Sciences, University of Tabuk, Tabuk 71491, Saudi Arabia; (R.M.); (R.I.B.); (Z.M.A.); (F.J.T.); (J.B.)
| | - Mohammad Muzaffar Mir
- Department of Clinical Biochemistry, College of Medicine, University of Bisha, Bisha 61922, Saudi Arabia;
| | - Mohammad Rehan Ajmal
- Department of Biochemistry, Faculty of Science, University of Tabuk, Tabuk 71491, Saudi Arabia; (S.M.A.); (M.R.A.)
| | - Faris Jamal Tayeb
- Department of Medical Laboratory Technology, Prince Fahad Bin Sultan Chair for Biomedical Research, Faculty of Applied Medical Sciences, University of Tabuk, Tabuk 71491, Saudi Arabia; (R.M.); (R.I.B.); (Z.M.A.); (F.J.T.); (J.B.)
| | - Jameel Barnawi
- Department of Medical Laboratory Technology, Prince Fahad Bin Sultan Chair for Biomedical Research, Faculty of Applied Medical Sciences, University of Tabuk, Tabuk 71491, Saudi Arabia; (R.M.); (R.I.B.); (Z.M.A.); (F.J.T.); (J.B.)
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Ashcroft FM. KATP Channels and the Metabolic Regulation of Insulin Secretion in Health and Disease: The 2022 Banting Medal for Scientific Achievement Award Lecture. Diabetes 2023; 72:693-702. [PMID: 37815796 PMCID: PMC10202764 DOI: 10.2337/dbi22-0030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Accepted: 02/28/2023] [Indexed: 10/11/2023]
Abstract
Diabetes is characterized by elevation of plasma glucose due to an insufficiency of the hormone insulin and is associated with both inadequate insulin secretion and impaired insulin action. The Banting Medal for Scientific Achievement Commemorates the work of Sir Frederick Banting, a member of the team that first used insulin to treat a patient with diabetes almost exactly one hundred years ago on 11 January 1922. This article is based on my Banting lecture of 2022 and concerns the mechanism of glucose-stimulated insulin secretion from pancreatic β-cells, with an emphasis on the metabolic regulation of the KATP channel. This channel plays a central role in insulin release. Its closure in response to metabolically generated changes in the intracellular concentrations of ATP and MgADP stimulates β-cell electrical activity and insulin granule exocytosis. Activating mutations in KATP channel genes that impair the ability of the channel to respond to ATP give rise to neonatal diabetes. Impaired KATP channel regulation may also play a role in type 2 diabetes. I conjecture that KATP channel closure in response to glucose is reduced because of impaired glucose metabolism, which fails to generate a sufficient increase in ATP. Consequently, glucose-stimulated β-cell electrical activity is less. As ATP is also required for insulin granule exocytosis, both reduced exocytosis and less β-cell electrical activity may contribute to the reduction in insulin secretion. I emphasize that what follows is not a definitive review of the topic but a personal account of the contribution of my team to the field that is based on my Banting lecture.
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Affiliation(s)
- Frances M. Ashcroft
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, U.K
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Samadli S, Zhou Q, Zheng B, Gu W, Zhang A. From glucose sensing to exocytosis: takes from maturity onset diabetes of the young. Front Endocrinol (Lausanne) 2023; 14:1188301. [PMID: 37255971 PMCID: PMC10226665 DOI: 10.3389/fendo.2023.1188301] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Accepted: 04/28/2023] [Indexed: 06/01/2023] Open
Abstract
Monogenic diabetes gave us simplified models of complex molecular processes occurring within β-cells, which allowed to explore the roles of numerous proteins from single protein perspective. Constellation of characteristic phenotypic features and wide application of genetic sequencing techniques to clinical practice, made the major form of monogenic diabetes - the Maturity Onset Diabetes of the Young to be distinguishable from type 1, type 2 as well as neonatal diabetes mellitus and understanding underlying molecular events for each type of MODY contributed to the advancements of antidiabetic therapy and stem cell research tremendously. The functional analysis of MODY-causing proteins in diabetes development, not only provided better care for patients suffering from diabetes, but also enriched our comprehension regarding the universal cellular processes including transcriptional and translational regulation, behavior of ion channels and transporters, cargo trafficking, exocytosis. In this review, we will overview structure and function of MODY-causing proteins, alterations in a particular protein arising from the deleterious mutations to the corresponding gene and their consequences, and translation of this knowledge into new treatment strategies.
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Affiliation(s)
- Sama Samadli
- Nanjing Key Laboratory of Pediatrics, Children’s Hospital of Nanjing Medical University, Nanjing, China
- Department of Pediatric Diseases II, Azerbaijan Medical University, Baku, Azerbaijan
| | - Qiaoli Zhou
- Department of Endocrinology, Children’s Hospital of Nanjing Medical University, Nanjing, China
| | - Bixia Zheng
- Nanjing Key Laboratory of Pediatrics, Children’s Hospital of Nanjing Medical University, Nanjing, China
| | - Wei Gu
- Department of Endocrinology, Children’s Hospital of Nanjing Medical University, Nanjing, China
| | - Aihua Zhang
- Nanjing Key Laboratory of Pediatrics, Children’s Hospital of Nanjing Medical University, Nanjing, China
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Bohuslavova R, Fabriciova V, Lebrón-Mora L, Malfatti J, Smolik O, Valihrach L, Benesova S, Zucha D, Berkova Z, Saudek F, Evans SM, Pavlinkova G. ISL1 controls pancreatic alpha cell fate and beta cell maturation. Cell Biosci 2023; 13:53. [PMID: 36899442 PMCID: PMC9999528 DOI: 10.1186/s13578-023-01003-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 03/01/2023] [Indexed: 03/12/2023] Open
Abstract
BACKGROUND Glucose homeostasis is dependent on functional pancreatic α and ß cells. The mechanisms underlying the generation and maturation of these endocrine cells remain unclear. RESULTS We unravel the molecular mode of action of ISL1 in controlling α cell fate and the formation of functional ß cells in the pancreas. By combining transgenic mouse models, transcriptomic and epigenomic profiling, we uncover that elimination of Isl1 results in a diabetic phenotype with a complete loss of α cells, disrupted pancreatic islet architecture, downregulation of key ß-cell regulators and maturation markers of ß cells, and an enrichment in an intermediate endocrine progenitor transcriptomic profile. CONCLUSIONS Mechanistically, apart from the altered transcriptome of pancreatic endocrine cells, Isl1 elimination results in altered silencing H3K27me3 histone modifications in the promoter regions of genes that are essential for endocrine cell differentiation. Our results thus show that ISL1 transcriptionally and epigenetically controls α cell fate competence, and ß cell maturation, suggesting that ISL1 is a critical component for generating functional α and ß cells.
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Affiliation(s)
- Romana Bohuslavova
- Laboratory of Molecular Pathogenetics, Institute of Biotechnology CAS, 25250, Vestec, Czechia.
| | - Valeria Fabriciova
- Laboratory of Molecular Pathogenetics, Institute of Biotechnology CAS, 25250, Vestec, Czechia
| | - Laura Lebrón-Mora
- Laboratory of Molecular Pathogenetics, Institute of Biotechnology CAS, 25250, Vestec, Czechia
| | - Jessica Malfatti
- Laboratory of Molecular Pathogenetics, Institute of Biotechnology CAS, 25250, Vestec, Czechia
| | - Ondrej Smolik
- Laboratory of Molecular Pathogenetics, Institute of Biotechnology CAS, 25250, Vestec, Czechia
| | - Lukas Valihrach
- Laboratory of Gene Expression, Institute of Biotechnology CAS, 25250, Vestec, Czechia
| | - Sarka Benesova
- Laboratory of Gene Expression, Institute of Biotechnology CAS, 25250, Vestec, Czechia
| | - Daniel Zucha
- Laboratory of Gene Expression, Institute of Biotechnology CAS, 25250, Vestec, Czechia
| | - Zuzana Berkova
- Laboratory of Pancreatic Islets, Institute for Clinical and Experimental Medicine, 14021, Prague, Czechia
| | - Frantisek Saudek
- Laboratory of Pancreatic Islets, Institute for Clinical and Experimental Medicine, 14021, Prague, Czechia
| | - Sylvia M Evans
- Department of Pharmacology; Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California at San Diego, La Jolla, CA, USA
| | - Gabriela Pavlinkova
- Laboratory of Molecular Pathogenetics, Institute of Biotechnology CAS, 25250, Vestec, Czechia.
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Elashi AA, Toor SM, Diboun I, Al-Sarraj Y, Taheri S, Suhre K, Abou-Samra AB, Albagha OME. The Genetic Spectrum of Maturity-Onset Diabetes of the Young (MODY) in Qatar, a Population-Based Study. Int J Mol Sci 2022; 24:ijms24010130. [PMID: 36613572 PMCID: PMC9820507 DOI: 10.3390/ijms24010130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 12/09/2022] [Accepted: 12/14/2022] [Indexed: 12/24/2022] Open
Abstract
Maturity-onset diabetes of the young (MODY) is a rare monogenic form of diabetes mellitus. In this study, we estimated the prevalence and genetic spectrum of MODY in the Middle Eastern population of Qatar using whole-genome sequencing (WGS) of 14,364 subjects from the population-based Qatar biobank (QBB) cohort. We focused our investigations on 14 previously identified genes ascribed to the cause of MODY and two potentially novel MODY-causing genes, RFX6 and NKX6-1. Genetic variations within the 16 MODY-related genes were assessed for their pathogenicity to identify disease-causing mutations. Analysis of QBB phenotype data revealed 72 subjects (0.5%) with type 1 diabetes, 2915 subjects (20.3%) with type 2 diabetes and 11,377 (79.2%) without diabetes. We identified 22 mutations in 67 subjects that were previously reported in the Human Genetic Mutation Database (HGMD) as disease-causing (DM) or likely disease causing (DM?) for MODY. We also identified 28 potentially novel MODY-causing mutations, predicted to be among the top 1% most deleterious mutations in the human genome, which showed complete (100%) disease penetrance in 34 subjects. Overall, we estimated that MODY accounts for around 2.2-3.4% of diabetes patients in Qatar. This is the first population-based study to determine the genetic spectrum and estimate the prevalence of MODY in the Middle East. Further research to characterize the newly identified mutations is warranted.
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Affiliation(s)
- Asma A. Elashi
- College of Health and Life Sciences (CHLS), Hamad Bin Khalifa University (HBKU), Qatar Foundation (QF), Doha P.O. Box 34110, Qatar
| | - Salman M. Toor
- College of Health and Life Sciences (CHLS), Hamad Bin Khalifa University (HBKU), Qatar Foundation (QF), Doha P.O. Box 34110, Qatar
| | - Ilhame Diboun
- College of Health and Life Sciences (CHLS), Hamad Bin Khalifa University (HBKU), Qatar Foundation (QF), Doha P.O. Box 34110, Qatar
- Medical and Population Genomics Lab, Sidra Medicine, Doha P.O. Box 26999, Qatar
| | - Yasser Al-Sarraj
- Qatar Genome Program (QGP), Qatar Foundation Research, Development and Innovation, Qatar Foundation (QF), Doha P.O. Box 5825, Qatar
| | - Shahrad Taheri
- Qatar Metabolic Institute, Hamad Medical Corporation, Doha P.O. Box 3050, Qatar
| | - Karsten Suhre
- Bioinformatics Core, Weill Cornell Medicine-Qatar, Education City, Doha P.O. Box 24144, Qatar
- Department of Biophysics and Physiology, Weill Cornell Medicine, New York, NY 10065, USA
| | | | - Omar M. E. Albagha
- College of Health and Life Sciences (CHLS), Hamad Bin Khalifa University (HBKU), Qatar Foundation (QF), Doha P.O. Box 34110, Qatar
- Centre for Genomic and Experimental Medicine, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh EH4 2XU, UK
- Correspondence: ; Tel.: +974-4454-2974
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Tran NQ, Truong SD, Ma PT, Hoang CK, Le BH, Dinh TTN, Van Tran L, Tran TV, Le LHG, Le KT, Nguyen HT, Vu HA, Mai TP, Do MD. Association of KCNJ11 and ABCC8 single-nucleotide polymorphisms with type 2 diabetes mellitus in a Kinh Vietnamese population. Medicine (Baltimore) 2022; 101:e31653. [PMID: 36401380 PMCID: PMC9678638 DOI: 10.1097/md.0000000000031653] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Type 2 diabetes mellitus (T2DM) is a genetically influenced disease, but few studies have been performed to investigate the genetic basis of T2DM in Vietnamese subjects. Thus, the potential associations of KCNJ11 and ABCC8 single nucleotide polymorphisms (SNPs) with T2DM were investigated in a Kinh Vietnamese population. A cross-sectional study consisting of 404 subjects including 202 T2DM cases and 202 non-T2DM controls was designed to examine the potential associations of 4 KCNJ11 and ABCC8 SNPs (rs5219, rs2285676, rs1799859, and rs757110) with T2DM. Genotypes were identified based on restriction fragment length polymorphism and tetra-primer amplification refractory mutation system polymerase chain reaction. After statistically adjusting for age, sex, and BMI, rs5219 was found to be associated with an increased risk of T2DM under 2 inheritance models: codominant (OR = 2.15, 95% confidence intervals [CI] = 1.09-4.22) and recessive (OR = 2.08, 95%CI = 1.09-3.94). On the other hand, rs2285676, rs1799859, and rs757110 were not associated with an increased risk of T2DM. Haplotype analysis elucidated a strong linkage disequilibrium between the 3 SNPs, rs5219, rs2285676, and rs757110. The haplotype rs5219(A)/rs2285676(T)/rs757110(G) was associated with an increased risk of T2DM (OR = 1.42, 95%CI = 1.01-1.99). The results show that rs5219 is a lead candidate SNP associated with an increased risk of developing T2DM in the Kinh Vietnamese population. Further functional characterization is needed to uncover the mechanism underlying the potential genotype-phenotype associations.
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Affiliation(s)
- Nam Quang Tran
- Department of Endocrinology, Faculty of Medicine, University of Medicine and Pharmacy at Ho Chi Minh City, Vietnam
- Department of Endocrinology, University Medical Center, University of Medicine and Pharmacy at Ho Chi Minh City, Vietnam
| | - Steven D. Truong
- Department of Medicine, School of Medicine, Stanford University, USA
| | - Phat Tung Ma
- Department of Endocrinology, Faculty of Medicine, University of Medicine and Pharmacy at Ho Chi Minh City, Vietnam
- Department of Endocrinology, University Medical Center, University of Medicine and Pharmacy at Ho Chi Minh City, Vietnam
| | - Chi Khanh Hoang
- Department of Endocrinology, University Medical Center, University of Medicine and Pharmacy at Ho Chi Minh City, Vietnam
| | - Bao Hoang Le
- Department of Endocrinology, University Medical Center, University of Medicine and Pharmacy at Ho Chi Minh City, Vietnam
| | - Thang Tat Ngo Dinh
- Department of Endocrinology, University Medical Center, University of Medicine and Pharmacy at Ho Chi Minh City, Vietnam
| | - Luong Van Tran
- Department of Endocrinology, University Medical Center, University of Medicine and Pharmacy at Ho Chi Minh City, Vietnam
| | - Thang Viet Tran
- Department of Endocrinology, Faculty of Medicine, University of Medicine and Pharmacy at Ho Chi Minh City, Vietnam
- Department of Endocrinology, University Medical Center, University of Medicine and Pharmacy at Ho Chi Minh City, Vietnam
| | - Linh Hoang Gia Le
- Center for Molecular Biomedicine, University of Medicine and Pharmacy at Ho Chi Minh City, Vietnam
| | - Khuong Thai Le
- Center for Molecular Biomedicine, University of Medicine and Pharmacy at Ho Chi Minh City, Vietnam
| | - Hien Thanh Nguyen
- Department of Medical Laboratory Technology, University of Medicine and Pharmacy at Ho Chi Minh City, Vietnam
| | - Hoang Anh Vu
- Center for Molecular Biomedicine, University of Medicine and Pharmacy at Ho Chi Minh City, Vietnam
| | - Thao Phuong Mai
- Department of Physiology-Pathophysiology-Immunology, Faculty of Medicine, University of Medicine and Pharmacy at Ho Chi Minh City, Vietnam
| | - Minh Duc Do
- Center for Molecular Biomedicine, University of Medicine and Pharmacy at Ho Chi Minh City, Vietnam
- * Correspondence: Minh Duc Do, Center for Molecular Biomedicine, University of Medicine and Pharmacy at Ho Chi Minh City, 217 Hong Bang, District 5, Ho Chi Minh City 700000, Vietnam (e-mail: )
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Role of Actionable Genes in Pursuing a True Approach of Precision Medicine in Monogenic Diabetes. Genes (Basel) 2022; 13:genes13010117. [PMID: 35052457 PMCID: PMC8774614 DOI: 10.3390/genes13010117] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 01/04/2022] [Accepted: 01/05/2022] [Indexed: 12/16/2022] Open
Abstract
Monogenic diabetes is a genetic disorder caused by one or more variations in a single gene. It encompasses a broad spectrum of heterogeneous conditions, including neonatal diabetes, maturity onset diabetes of the young (MODY) and syndromic diabetes, affecting 1-5% of patients with diabetes. Some of these variants are harbored by genes whose altered function can be tackled by specific actions ("actionable genes"). In suspected patients, molecular diagnosis allows the implementation of effective approaches of precision medicine so as to allow individual interventions aimed to prevent, mitigate or delay clinical outcomes. This review will almost exclusively concentrate on the clinical strategy that can be specifically pursued in carriers of mutations in "actionable genes", including ABCC8, KCNJ11, GCK, HNF1A, HNF4A, HNF1B, PPARG, GATA4 and GATA6. For each of them we will provide a short background on what is known about gene function and dysfunction. Then, we will discuss how the identification of their mutations in individuals with this form of diabetes, can be used in daily clinical practice to implement specific monitoring and treatments. We hope this article will help clinical diabetologists carefully consider who of their patients deserves timely genetic testing for monogenic diabetes.
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Ali Khan I. Do second generation sequencing techniques identify documented genetic markers for neonatal diabetes mellitus? Heliyon 2021; 7:e07903. [PMID: 34584998 PMCID: PMC8455689 DOI: 10.1016/j.heliyon.2021.e07903] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 01/15/2021] [Accepted: 08/27/2021] [Indexed: 12/24/2022] Open
Abstract
Neonatal diabetes mellitus (NDM) is noted as a genetic, heterogeneous, and rare disease in infants. NDM occurs due to a single-gene mutation in neonates. A common source for developing NDM in an infant is the existence of mutations/variants in the KCNJ11 and ABCC8 genes, encoding the subunits of the voltage-dependent potassium channel. Both KCNJ11 and ABCC8 genes are useful in diagnosing monogenic diabetes during infancy. Genetic analysis was previously performed using first-generation sequencing techniques, such as DNA-Sanger sequencing, which uses chain-terminating inhibitors. Sanger sequencing has certain limitations; it can screen a limited region of exons in one gene, but it cannot screen large regions of the human genome. In the last decade, first generation sequencing techniques have been replaced with second-generation sequencing techniques, such as next-generation sequencing (NGS), which sequences nucleic-acids more rapidly and economically than Sanger sequencing. NGS applications are involved in whole exome sequencing (WES), whole genome sequencing (WGS), and targeted gene panels. WES characterizes a substantial breakthrough in human genetics. Genetic testing for custom genes allows the screening of the complete gene, including introns and exons. The aim of this review was to confirm if the 22 genetic variations previously documented to cause NDM by Sanger sequencing could be detected using second generation sequencing techniques. The author has cross-checked global studies performed in NDM using NGS, ES/WES, WGS, and targeted gene panels as second-generation sequencing techniques; WES confirmed the similar variants, which have been previously documented with Sanger sequencing. WES is documented as a powerful tool and WGS as the most comprehensive test for verified the documented variants, as well as novel enhancers. This review recommends for the future studies should be performed with second generation sequencing techniques to identify the verified 22 genetic and novel variants by screening in NDM (PNDM or TNMD) children.
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Affiliation(s)
- Imran Ali Khan
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, King Saud University, PO Box-10219, Riyadh, 11433, Saudi Arabia
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Abstract
OBJECTIVE To describe the spectrum of neonatal diabetes mellitus (NDM), document new mutations, and review published Indian literature on the etiology of NDM. METHODS Retrospective analysis of the clinical and genetic profile of 12 NDM patients. RESULTS Eight patients presented with NDM before the age of 6 mo. Three other patients, including 2 siblings presented in later part of infancy. An additional patient was diagnosed at age 5 y with the same etiology as her infant sibling. Four patients had transient diabetes [TNDM:1 each with a mutation in KCNJ11 and INS gene, 2 with ABCC8 mutation], 7 had permanent diabetes [PNDM: 2 siblings with complete glucokinase deficiency, 2 siblings with thiamine responsive megaloblastic anemia (TRMA), 1 with Immune dysregulation, Polyendocrinopathy, Enteropathy, X-linked (IPEX) syndrome and 2 with Wolcott Rallison syndrome, (WRS)]. Four patients had 5 novel mutations. Genetic etiology could not be established in 1 patient with features of insulin resistance. Poorly controlled blood glucose in the TRMA patient led to hyperglycemia-induced hemichorea-hemiballismus, a rare manifestation in children. CONCLUSIONS The authors describe 5 novel mutations, in the EIF2AK3, ABCC8, and GCK genes, a homozygous mutation at the ABCC8 locus presenting as TNDM, an obscure phenotype of the GCK gene mutation, and hyperglycemia-induced hemichorea-hemiballismus in a patient with TRMA. In India, PNDM is most commonly due to WRS similar to Middle Eastern countries with high consanguinity rates.
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Sachse G, Haythorne E, Hill T, Proks P, Joynson R, Terrón-Expósito R, Bentley L, Tucker SJ, Cox RD, Ashcroft FM. The KCNJ11-E23K Gene Variant Hastens Diabetes Progression by Impairing Glucose-Induced Insulin Secretion. Diabetes 2021; 70:1145-1156. [PMID: 33568422 DOI: 10.2337/db20-0691] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 02/05/2021] [Indexed: 11/13/2022]
Abstract
The ATP-sensitive K+ (KATP) channel controls blood glucose levels by coupling glucose metabolism to insulin secretion in pancreatic β-cells. E23K, a common polymorphism in the pore-forming KATP channel subunit (KCNJ11) gene, has been linked to increased risk of type 2 diabetes. Understanding the risk-allele-specific pathogenesis has the potential to improve personalized diabetes treatment, but the underlying mechanism has remained elusive. Using a genetically engineered mouse model, we now show that the K23 variant impairs glucose-induced insulin secretion and increases diabetes risk when combined with a high-fat diet (HFD) and obesity. KATP-channels in β-cells with two K23 risk alleles (KK) showed decreased ATP inhibition, and the threshold for glucose-stimulated insulin secretion from KK islets was increased. Consequently, the insulin response to glucose and glycemic control was impaired in KK mice fed a standard diet. On an HFD, the effects of the KK genotype were exacerbated, accelerating diet-induced diabetes progression and causing β-cell failure. We conclude that the K23 variant increases diabetes risk by impairing insulin secretion at threshold glucose levels, thus accelerating loss of β-cell function in the early stages of diabetes progression.
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Affiliation(s)
- Gregor Sachse
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, U.K.
| | - Elizabeth Haythorne
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, U.K
| | - Thomas Hill
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, U.K
| | - Peter Proks
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, U.K
- Department of Physics, University of Oxford, Oxford, U.K
| | - Russell Joynson
- Mammalian Genetics Unit and Mary Lyon Centre, MRC Harwell Institute, Oxfordshire, U.K
| | - Raul Terrón-Expósito
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, U.K
| | - Liz Bentley
- Mammalian Genetics Unit and Mary Lyon Centre, MRC Harwell Institute, Oxfordshire, U.K
| | | | - Roger D Cox
- Mammalian Genetics Unit and Mary Lyon Centre, MRC Harwell Institute, Oxfordshire, U.K
| | - Frances M Ashcroft
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, U.K
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Abstract
The endoderm is the innermost germ layer that forms the linings of the respiratory and gastrointestinal tracts, and their associated organs, during embryonic development. Xenopus embryology experiments have provided fundamental insights into how the endoderm develops in vertebrates, including the critical role of TGFβ-signaling in endoderm induction,elucidating the gene regulatory networks controlling germ layer development and the key molecular mechanisms regulating endoderm patterning and morphogenesis. With new genetic, genomic, and imaging approaches, Xenopus is now routinely used to model human disease, discover mechanisms underlying endoderm organogenesis, and inform differentiation protocols for pluripotent stem cell differentiation and regenerative medicine applications. In this chapter, we review historical and current discoveries of endoderm development in Xenopus, then provide examples of modeling human disease and congenital defects of endoderm-derived organs using Xenopus.
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Affiliation(s)
- Nicole A Edwards
- Division of Developmental Biology, Center for Stem Cell and Organoid Medicine, Perinatal Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States.
| | - Aaron M Zorn
- Division of Developmental Biology, Center for Stem Cell and Organoid Medicine, Perinatal Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, United States.
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12
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Pipatpolkai T, Usher S, Stansfeld PJ, Ashcroft FM. New insights into K ATP channel gene mutations and neonatal diabetes mellitus. Nat Rev Endocrinol 2020; 16:378-393. [PMID: 32376986 DOI: 10.1038/s41574-020-0351-y] [Citation(s) in RCA: 72] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/17/2020] [Indexed: 12/12/2022]
Abstract
The ATP-sensitive potassium channel (KATP channel) couples blood levels of glucose to insulin secretion from pancreatic β-cells. KATP channel closure triggers a cascade of events that results in insulin release. Metabolically generated changes in the intracellular concentrations of adenosine nucleotides are integral to this regulation, with ATP and ADP closing the channel and MgATP and MgADP increasing channel activity. Activating mutations in the genes encoding either of the two types of KATP channel subunit (Kir6.2 and SUR1) result in neonatal diabetes mellitus, whereas loss-of-function mutations cause hyperinsulinaemic hypoglycaemia of infancy. Sulfonylurea and glinide drugs, which bind to SUR1, close the channel through a pathway independent of ATP and are now the primary therapy for neonatal diabetes mellitus caused by mutations in the genes encoding KATP channel subunits. Insight into the molecular details of drug and nucleotide regulation of channel activity has been illuminated by cryo-electron microscopy structures that reveal the atomic-level organization of the KATP channel complex. Here we review how these structures aid our understanding of how the various mutations in the genes encoding Kir6.2 (KCNJ11) and SUR1 (ABCC8) lead to a reduction in ATP inhibition and thereby neonatal diabetes mellitus. We also provide an update on known mutations and sulfonylurea therapy in neonatal diabetes mellitus.
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Affiliation(s)
- Tanadet Pipatpolkai
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Samuel Usher
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Phillip J Stansfeld
- Department of Biochemistry, University of Oxford, Oxford, UK
- School of Life Sciences, University of Warwick, Coventry, UK
- Department of Chemistry, University of Warwick, Coventry, UK
| | - Frances M Ashcroft
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.
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13
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Webb DR, Davies MJ, Jarvis J, Seidu S, Khunti K. The right place for Sulphonylureas today. Diabetes Res Clin Pract 2019; 157:107836. [PMID: 31479704 DOI: 10.1016/j.diabres.2019.107836] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 08/22/2019] [Indexed: 12/28/2022]
Abstract
The place of Sulphonylurea based insulin secretagogues in the management of Type 2 diabetes appears as controversial today as it was fifty years ago. Newer therapies are associated with less hypoglycaemia and weight gain than Sulphonylureas but currently cost more and lack assurances which come with long-term exposure. Emergence of recent CVOT data for SGLT-2 inhibitors and GLP-1 receptor agonists is likely to influence therapeutic choices and guidance is now supportive of their earlier use in cases at high risk of cardiovascular disease. Meta-analyses of Sulphonylurea trials have failed to indicate a consistent effect (positive or negative) on cardiovascular disease or mortality, although are limited by the relative scarcity of studies directly reporting these outcomes. The CAROLINA trial is reassuring in demonstrating cardiovascular safety for the Sulphonylurea Glimepiride when compared directly with the DPP-4 inhibitor Linagliptin, suggesting either of these agents would be relatively safe second line options after Metformin in the majority of patients. This review provides a balanced assessment of available Sulphonylurea treatments in the context of current cardiovascular outcome trial data (CVOT) data and hopefully assists informed decision making about the place of these drugs in contemporary glucose lowering practice.
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Affiliation(s)
- David R Webb
- University of Leicester, Diabetes Research Centre, Leicester Diabetes Centre, Leicester General Hospital, Gwendolen Road, Leicester LE5 4PW, UK.
| | - Melanie J Davies
- University of Leicester, Diabetes Research Centre, Leicester Diabetes Centre, Leicester General Hospital, Gwendolen Road, Leicester LE5 4PW, UK.
| | - Janet Jarvis
- University Hospitals of Leicester NHS Trust, Leicester Diabetes Centre, Leicester General Hospital, Gwendolen Road, Leicester LE5 4PW, UK.
| | - Sam Seidu
- University of Leicester, Diabetes Research Centre, Leicester Diabetes Centre, Leicester General Hospital, Gwendolen Road, Leicester LE5 4PW, UK.
| | - Kamlesh Khunti
- University of Leicester, Diabetes Research Centre, Leicester Diabetes Centre, Leicester General Hospital, Gwendolen Road, Leicester LE5 4PW, UK.
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14
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Balamurugan K, Kavitha B, Yang Z, Mohan V, Radha V, Shyng SL. Functional characterization of activating mutations in the sulfonylurea receptor 1 (ABCC8) causing neonatal diabetes mellitus in Asian Indian children. Pediatr Diabetes 2019; 20:397-407. [PMID: 30861254 PMCID: PMC11423867 DOI: 10.1111/pedi.12843] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2018] [Revised: 01/28/2019] [Accepted: 02/24/2019] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND Gain-of-function of ATP-sensitive K+ (KATP ) channels because of mutations in the genes encoding SUR1 (ABCC8) or Kir6.2 (KCNJ11) is a major cause of neonatal diabetes mellitus (NDM). Our aim is to determine molecular defects in KATP channels caused by ABCC8 mutations in Asian Indian children with NDM by in vitro functional studies. METHODS Wild-type (WT; NM_000352.4) or mutant sulfonylurea receptor 1 (SUR1) and Kir6.2 were co-expressed in COSm6 cells. Biogenesis efficiency and surface expression of mutant channels were assessed by immunoblotting and immunostaining. The response of mutant channels to cytoplasmic ATP and ADP was assessed by inside-out patch-clamp recordings. The response of mutant channels to known KATP inhibitors in intact cells were determined by 86 Rb efflux assays. RESULTS Five SUR1 missense mutations, D212Y, P254S, R653Q, R992C, and Q1224H, were studied and showed increased activity in MgATP/MgADP. Two of the mutants, D212Y and P254S, also showed reduced response to ATP4- inhibition, as well as markedly reduced surface expression. Moreover, all five mutants were inhibited by the KATP channel inhibitors glibenclamide and carbamazepine. CONCLUSIONS The study shows the mechanisms by which five SUR1 mutations identified in Asian Indian NDM patients affect KATP channel function to cause the disease. The reduced ATP4- sensitivity caused by the D212Y and P254S mutations in the L0 of SUR1 provides novel insight into the role of L0 in channel inhibition by ATP. The results also explain why sulfonylurea therapy is effective in two patients and inform how it should be effective for the other three patients.
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Affiliation(s)
- Kandasamy Balamurugan
- Department of Molecular Genetics, Madras Diabetes Research Foundation, ICMR Advanced Centre for Genomics of Type 2 Diabetes and Dr. Mohan's Diabetes Specialties Centre, WHO Collaborating Centre for Non-Communicable Diseases Prevention & Control, IDF Centre of Education, Chennai, India
- Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, Oregon
| | - Babu Kavitha
- Department of Molecular Genetics, Madras Diabetes Research Foundation, ICMR Advanced Centre for Genomics of Type 2 Diabetes and Dr. Mohan's Diabetes Specialties Centre, WHO Collaborating Centre for Non-Communicable Diseases Prevention & Control, IDF Centre of Education, Chennai, India
| | - Zhongying Yang
- Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, Oregon
| | - Viswanathan Mohan
- Department of Molecular Genetics, Madras Diabetes Research Foundation, ICMR Advanced Centre for Genomics of Type 2 Diabetes and Dr. Mohan's Diabetes Specialties Centre, WHO Collaborating Centre for Non-Communicable Diseases Prevention & Control, IDF Centre of Education, Chennai, India
| | - Venkatesan Radha
- Department of Molecular Genetics, Madras Diabetes Research Foundation, ICMR Advanced Centre for Genomics of Type 2 Diabetes and Dr. Mohan's Diabetes Specialties Centre, WHO Collaborating Centre for Non-Communicable Diseases Prevention & Control, IDF Centre of Education, Chennai, India
| | - Show-Ling Shyng
- Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, Oregon
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15
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Ion Transporters, Channelopathies, and Glucose Disorders. Int J Mol Sci 2019; 20:ijms20102590. [PMID: 31137773 PMCID: PMC6566632 DOI: 10.3390/ijms20102590] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 05/21/2019] [Accepted: 05/22/2019] [Indexed: 01/19/2023] Open
Abstract
Ion channels and transporters play essential roles in excitable cells including cardiac, skeletal and smooth muscle cells, neurons, and endocrine cells. In pancreatic beta-cells, for example, potassium KATP channels link the metabolic signals generated inside the cell to changes in the beta-cell membrane potential, and ultimately regulate insulin secretion. Mutations in the genes encoding some ion transporter and channel proteins lead to disorders of glucose homeostasis (hyperinsulinaemic hypoglycaemia and different forms of diabetes mellitus). Pancreatic KATP, Non-KATP, and some calcium channelopathies and MCT1 transporter defects can lead to various forms of hyperinsulinaemic hypoglycaemia (HH). Mutations in the genes encoding the pancreatic KATP channels can also lead to different types of diabetes (including neonatal diabetes mellitus (NDM) and Maturity Onset Diabetes of the Young, MODY), and defects in the solute carrier family 2 member 2 (SLC2A2) leads to diabetes mellitus as part of the Fanconi–Bickel syndrome. Variants or polymorphisms in some ion channel genes and transporters have been reported in association with type 2 diabetes mellitus.
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16
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Cordiner RLM, Pearson ER. Reflections on the sulphonylurea story: A drug class at risk of extinction or a drug class worth reviving? Diabetes Obes Metab 2019; 21:761-771. [PMID: 30471177 DOI: 10.1111/dom.13596] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2018] [Revised: 11/15/2018] [Accepted: 11/20/2018] [Indexed: 01/12/2023]
Abstract
The role of sulphonylureas (SUs) in modern clinical practice poses ongoing clinical debate. With the advent of newer agents in diabetes management, there is an increasing shift away from the prescribing of SUs, but not necessarily to more effective agents. This review provides a different perspective on the debate, reflecting in depth upon the physiology of SUs, drawing on insights gained from monogenic diabetes to highlight the potential benefit of lower doses of SUs, and the probable benefit of gliclazide over most other, if not all SUs, in terms of sulphonylurea failure and cardiovascular outcomes.
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17
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Tinker A, Aziz Q, Li Y, Specterman M. ATP‐Sensitive Potassium Channels and Their Physiological and Pathophysiological Roles. Compr Physiol 2018; 8:1463-1511. [DOI: 10.1002/cphy.c170048] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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18
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Rorsman P, Ashcroft FM. Pancreatic β-Cell Electrical Activity and Insulin Secretion: Of Mice and Men. Physiol Rev 2018; 98:117-214. [PMID: 29212789 PMCID: PMC5866358 DOI: 10.1152/physrev.00008.2017] [Citation(s) in RCA: 456] [Impact Index Per Article: 76.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 05/30/2017] [Accepted: 06/18/2017] [Indexed: 12/14/2022] Open
Abstract
The pancreatic β-cell plays a key role in glucose homeostasis by secreting insulin, the only hormone capable of lowering the blood glucose concentration. Impaired insulin secretion results in the chronic hyperglycemia that characterizes type 2 diabetes (T2DM), which currently afflicts >450 million people worldwide. The healthy β-cell acts as a glucose sensor matching its output to the circulating glucose concentration. It does so via metabolically induced changes in electrical activity, which culminate in an increase in the cytoplasmic Ca2+ concentration and initiation of Ca2+-dependent exocytosis of insulin-containing secretory granules. Here, we review recent advances in our understanding of the β-cell transcriptome, electrical activity, and insulin exocytosis. We highlight salient differences between mouse and human β-cells, provide models of how the different ion channels contribute to their electrical activity and insulin secretion, and conclude by discussing how these processes become perturbed in T2DM.
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Affiliation(s)
- Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, United Kingdom; Department of Neuroscience and Physiology, Metabolic Research Unit, Göteborg, Sweden; and Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Frances M Ashcroft
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, United Kingdom; Department of Neuroscience and Physiology, Metabolic Research Unit, Göteborg, Sweden; and Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
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19
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McClenaghan C, Hanson A, Sala-Rabanal M, Roessler HI, Josifova D, Grange DK, van Haaften G, Nichols CG. Cantu syndrome-associated SUR2 (ABCC9) mutations in distinct structural domains result in K ATP channel gain-of-function by differential mechanisms. J Biol Chem 2017; 293:2041-2052. [PMID: 29275331 DOI: 10.1074/jbc.ra117.000351] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 12/20/2017] [Indexed: 12/25/2022] Open
Abstract
The complex disorder Cantu syndrome (CS) arises from gain-of-function mutations in either KCNJ8 or ABCC9, the genes encoding the Kir6.1 and SUR2 subunits of ATP-sensitive potassium (KATP) channels, respectively. Recent reports indicate that such mutations can increase channel activity by multiple molecular mechanisms. In this study, we determined the mechanism by which KATP function is altered by several substitutions in distinct structural domains of SUR2: D207E in the intracellular L0-linker and Y985S, G989E, M1060I, and R1154Q/R1154W in TMD2. We engineered substitutions at their equivalent positions in rat SUR2A (D207E, Y981S, G985E, M1056I, and R1150Q/R1150W) and investigated functional consequences using macroscopic rubidium (86Rb+) efflux assays and patch-clamp electrophysiology. Our results indicate that D207E increases KATP channel activity by increasing intrinsic stability of the open state, whereas the cluster of Y981S/G985E/M1056I substitutions, as well as R1150Q/R1150W, augmented Mg-nucleotide activation. We also tested the responses of these channel variants to inhibition by the sulfonylurea drug glibenclamide, a potential pharmacotherapy for CS. None of the D207E, Y981S, G985E, or M1056I substitutions had a significant effect on glibenclamide sensitivity. However, Gln and Trp substitution at Arg-1150 significantly decreased glibenclamide potency. In summary, these results provide additional confirmation that mutations in CS-associated SUR2 mutations result in KATP gain-of-function. They help link CS genotypes to phenotypes and shed light on the underlying molecular mechanisms, including consequences for inhibitory drug sensitivity, insights that may inform the development of therapeutic approaches to manage CS.
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Affiliation(s)
| | - Alex Hanson
- From the Departments of Cell Biology and Physiology and
| | | | - Helen I Roessler
- the Department of Medical Genetics, University Medical Center Utrecht, Postbus 85500, 3508 GA Utrecht, The Netherlands, and
| | - Dragana Josifova
- the Guy's and St. Thomas NHS Trust, Clinical Genetics Department, Great Maze Pond, London SE1 9RT, United Kingdom
| | - Dorothy K Grange
- Pediatrics, Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, Saint Louis, Missouri 63110
| | - Gijs van Haaften
- the Department of Medical Genetics, University Medical Center Utrecht, Postbus 85500, 3508 GA Utrecht, The Netherlands, and
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20
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Yang YY, Long RK, Ferrara CT, Gitelman SE, German MS, Yang SB. A new familial form of a late-onset, persistent hyperinsulinemic hypoglycemia of infancy caused by a novel mutation in KCNJ11. Channels (Austin) 2017; 11:636-647. [PMID: 29087246 PMCID: PMC5786184 DOI: 10.1080/19336950.2017.1393131] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The ATP-sensitive potassium channel (KATP) functions as a metabo-electric transducer in regulating insulin secretion from pancreatic β-cells. The pancreatic KATP channel is composed of a pore-forming inwardly-rectifying potassium channel, Kir6.2, and a regulatory subunit, sulphonylurea receptor 1 (SUR1). Loss-of-function mutations in either subunit often lead to the development of persistent hyperinsulinemic hypoglycemia of infancy (PHHI). PHHI is a rare genetic disease and most patients present with immediate onset within the first few days after birth. In this study, we report an unusual form of PHHI, in which the index patient developed hyperinsulinemic hypoglycemia after 1 year of age. The patient failed to respond to routine medication for PHHI and underwent a complete pancreatectomy. Genotyping of the index patient and his immediate family members showed that the patient and other family members with hypoglycemic episodes carried a heterozygous novel mutation in KCNJ11 (C83T), which encodes Kir6.2 (A28V). Electrophysiological and cell biological experiments revealed that A28V hKir6.2 is a dominant-negative, loss-of-function mutation and that KATP channels carrying this mutation failed to reach the cell surface. De novo protein structure prediction indicated that this A28V mutation reoriented the ER retention motif located at the C-terminal of the hKir6.2, and this result may explain the trafficking defect caused by this point mutation. Our study is the first report of a novel form of late-onset PHHI that is caused by a dominant mutation in KCNJ11 and exhibits a defect in proper surface expression of Kir6.2.
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Affiliation(s)
- Yen-Yu Yang
- a Institute of Biomedical Sciences, Academia Sinica , Taipei , Taiwan
| | - Roger K Long
- b Department of Pediatrics , University of California San Francisco , USA
| | | | - Stephen E Gitelman
- b Department of Pediatrics , University of California San Francisco , USA.,c Diabetes Center , University of California San Francisco , USA
| | - Michael S German
- c Diabetes Center , University of California San Francisco , USA.,d Department of Medicine and Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research , University of California San Francisco , USA
| | - Shi-Bing Yang
- a Institute of Biomedical Sciences, Academia Sinica , Taipei , Taiwan
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21
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Abstract
Since the discovery of the KATP channel in 1983, numerous studies have revealed its physiological functions. The KATP channel is expressed in various organs, including the pancreas, brain and skeletal muscles. It functions as a "metabolic sensor" that converts the metabolic status to electrical activity. In pancreatic beta-cells, the KATP channel regulates the secretion of insulin by sensing a change in the blood glucose level and thus maintains glucose homeostasis. In 2004, heterozygous gain-of-function mutations in the KCNJ11 gene, which encodes the Kir6.2 subunit of the KATP channel, were found to cause neonatal diabetes. In some mutations, diabetes is accompanied by severe neurological symptoms [developmental delay, epilepsy, neonatal diabetes (DEND) syndrome]. This review focuses on mutations of Kir6.2, the pore-forming subunit and sulfonylurea receptor (SUR) 1, the regulatory subunit of the KATP channel, which cause neonatal diabetes/DEND syndrome and also discusses the findings of the pathological mechanisms that are associated with neonatal diabetes, and its neurological features.
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Affiliation(s)
- Kenju Shimomura
- Department of Medical Electrophysiology, Fukushima Medical University School of Medicine, Japan
| | - Yuko Maejima
- Department of Medical Electrophysiology, Fukushima Medical University School of Medicine, Japan
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22
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Flanagan SE, Dũng VC, Houghton JAL, De Franco E, Ngoc CTB, Damhuis A, Ashcroft FM, Harries LW, Ellard S. An ABCC8 Nonsense Mutation Causing Neonatal Diabetes Through Altered Transcript Expression. J Clin Res Pediatr Endocrinol 2017; 9:260-264. [PMID: 28663158 PMCID: PMC5596808 DOI: 10.4274/jcrpe.4624] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The pancreatic ATP-sensitive K+ (K-ATP) channel is a key regulator of insulin secretion. Gain-of-function mutations in the genes encoding the Kir6.2 (KCNJ11) and SUR1 (ABCC8) subunits of the channel cause neonatal diabetes, whilst loss-of-function mutations in these genes result in congenital hyperinsulinism. We report two patients with neonatal diabetes in whom we unexpectedly identified recessively inherited loss-of-function mutations. The aim of this study was to investigate how a homozygous nonsense mutation in ABCC8 could result in neonatal diabetes. The ABCC8 p.Glu747* was identified in two unrelated Vietnamese patients. This mutation is located within the in-frame exon 17 and RNA studies confirmed (a) the absence of full length SUR1 mRNA and (b) the presence of the alternatively spliced transcript lacking exon 17. Successful transfer of both patients to sulphonylurea treatment suggests that the altered transcript expression enhances the sensitivity of the K-ATP channel to Mg-ADP/ATP. This is the first report of an ABCC8 nonsense mutation causing a gain-of-channel function and these findings extend the spectrum of K-ATP channel mutations observed in patients with neonatal diabetes.
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Affiliation(s)
- Sarah E. Flanagan
- University of Exeter Medical School, Institute of Biomedical and Clinical Science, Department of Molecular Genetics, Exeter, United Kingdom
,* Address for Correspondence: University of Exeter Medical School, Institute of Biomedical and Clinical Science, Department of Molecular Genetics, Exeter, United Kingdom E-mail:
| | - Vũ Chí Dũng
- National Children’s Hospital, Department of Endocrinology, Metabolism and Genetics, Hanoi, Vietnam
| | - Jayne A. L. Houghton
- University of Exeter Medical School, Institute of Biomedical and Clinical Science, Department of Molecular Genetics, Exeter, United Kingdom
| | - Elisa De Franco
- University of Exeter Medical School, Institute of Biomedical and Clinical Science, Department of Molecular Genetics, Exeter, United Kingdom
| | - Can Thi Bich Ngoc
- National Children’s Hospital, Department of Endocrinology, Metabolism and Genetics, Hanoi, Vietnam
| | - Annet Damhuis
- University of Exeter Medical School, Institute of Biomedical and Clinical Science, Department of Molecular Genetics, Exeter, United Kingdom
| | - Frances M. Ashcroft
- University of Oxford, Henry Wellcome Centre for Gene Function, Department of Physiology, Anatomy and Genetics, Oxford, United Kingdom
| | - Lorna W. Harries
- University of Exeter Medical School, Institute of Biomedical and Clinical Science, Department of Molecular Genetics, Exeter, United Kingdom
| | - Sian Ellard
- University of Exeter Medical School, Institute of Biomedical and Clinical Science, Department of Molecular Genetics, Exeter, United Kingdom
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23
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Zammit MA, Agius SM, Calleja-Agius J. Transient Neonatal Diabetes Mellitus: A Challenge and Opportunity for Specialized Nursing Care. Neonatal Netw 2017; 36:196-205. [PMID: 28764822 DOI: 10.1891/0730-0832.36.4.196] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Transient neonatal diabetes mellitus (TNDM) is a rare disorder, with a reported incidence of approximately 1 in 450,000 live births. It is characterized by insulin-requiring hyperglycemia in the neonatal period. The disease improves by early childhood, but the patient may relapse in later life. Diagnosis is made after genetic testing following presentation with hyperglycemia not conforming to Type 1 or Type 2 diabetes. Management is based on insulin and possible sulfonylurea administration. Three genetically distinct subtypes of TNDM are recognized. Type 1 TNDM is due to overexpression of genes at the 6q24 locus, whereas the 11p15 locus is involved in Type 2 and 3 TNDM. In this article the clinical presentation, management, and genetics of TNDM are discussed, particularly emphasizing the role of the neonatal nurse.
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24
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Ashcroft FM, Puljung MC, Vedovato N. Neonatal Diabetes and the K ATP Channel: From Mutation to Therapy. Trends Endocrinol Metab 2017; 28:377-387. [PMID: 28262438 PMCID: PMC5582192 DOI: 10.1016/j.tem.2017.02.003] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Revised: 01/30/2017] [Accepted: 02/01/2017] [Indexed: 12/25/2022]
Abstract
Activating mutations in one of the two subunits of the ATP-sensitive potassium (KATP) channel cause neonatal diabetes (ND). This may be either transient or permanent and, in approximately 20% of patients, is associated with neurodevelopmental delay. In most patients, switching from insulin to oral sulfonylurea therapy improves glycemic control and ameliorates some of the neurological disabilities. Here, we review how KATP channel mutations lead to the varied clinical phenotype, how sulfonylureas exert their therapeutic effects, and why their efficacy varies with individual mutations.
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Affiliation(s)
- Frances M Ashcroft
- Henry Wellcome Centre for Gene Function, Department of Physiology, Anatomy and Genetics, University of Oxford, OX1 3PT, UK.
| | - Michael C Puljung
- Henry Wellcome Centre for Gene Function, Department of Physiology, Anatomy and Genetics, University of Oxford, OX1 3PT, UK
| | - Natascia Vedovato
- Henry Wellcome Centre for Gene Function, Department of Physiology, Anatomy and Genetics, University of Oxford, OX1 3PT, UK
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25
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Velasco M, Díaz-García CM, Larqué C, Hiriart M. Modulation of Ionic Channels and Insulin Secretion by Drugs and Hormones in Pancreatic Beta Cells. Mol Pharmacol 2016; 90:341-57. [PMID: 27436126 DOI: 10.1124/mol.116.103861] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 07/18/2016] [Indexed: 12/11/2022] Open
Abstract
Pancreatic beta cells, unique cells that secrete insulin in response to an increase in glucose levels, play a significant role in glucose homeostasis. Glucose-stimulated insulin secretion (GSIS) in pancreatic beta cells has been extensively explored. In this mechanism, glucose enters the cells and subsequently the metabolic cycle. During this process, the ATP/ADP ratio increases, leading to ATP-sensitive potassium (KATP) channel closure, which initiates depolarization that is also dependent on the activity of TRP nonselective ion channels. Depolarization leads to the opening of voltage-gated Na(+) channels (Nav) and subsequently voltage-dependent Ca(2+) channels (Cav). The increase in intracellular Ca(2+) triggers the exocytosis of insulin-containing vesicles. Thus, electrical activity of pancreatic beta cells plays a central role in GSIS. Moreover, many growth factors, incretins, neurotransmitters, and hormones can modulate GSIS, and the channels that participate in GSIS are highly regulated. In this review, we focus on the principal ionic channels (KATP, Nav, and Cav channels) involved in GSIS and how classic and new proteins, hormones, and drugs regulate it. Moreover, we also discuss advances on how metabolic disorders such as metabolic syndrome and diabetes mellitus change channel activity leading to changes in insulin secretion.
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Affiliation(s)
- Myrian Velasco
- Department of Neurodevelopment and Physiology, Neuroscience Division, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Carlos Manlio Díaz-García
- Department of Neurodevelopment and Physiology, Neuroscience Division, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Carlos Larqué
- Department of Neurodevelopment and Physiology, Neuroscience Division, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Marcia Hiriart
- Department of Neurodevelopment and Physiology, Neuroscience Division, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
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