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Abu Aqel Y, Alnesf A, Aigha II, Islam Z, Kolatkar PR, Teo A, Abdelalim EM. Glucokinase (GCK) in diabetes: from molecular mechanisms to disease pathogenesis. Cell Mol Biol Lett 2024; 29:120. [PMID: 39245718 PMCID: PMC11382428 DOI: 10.1186/s11658-024-00640-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2024] [Accepted: 08/23/2024] [Indexed: 09/10/2024] Open
Abstract
Glucokinase (GCK), a key enzyme in glucose metabolism, plays a central role in glucose sensing and insulin secretion in pancreatic β-cells, as well as glycogen synthesis in the liver. Mutations in the GCK gene have been associated with various monogenic diabetes (MD) disorders, including permanent neonatal diabetes mellitus (PNDM) and maturity-onset diabetes of the young (MODY), highlighting its importance in maintaining glucose homeostasis. Additionally, GCK gain-of-function mutations lead to a rare congenital form of hyperinsulinism known as hyperinsulinemic hypoglycemia (HH), characterized by increased enzymatic activity and increased glucose sensitivity in pancreatic β-cells. This review offers a comprehensive exploration of the critical role played by the GCK gene in diabetes development, shedding light on its expression patterns, regulatory mechanisms, and diverse forms of associated monogenic disorders. Structural and mechanistic insights into GCK's involvement in glucose metabolism are discussed, emphasizing its significance in insulin secretion and glycogen synthesis. Animal models have provided valuable insights into the physiological consequences of GCK mutations, although challenges remain in accurately recapitulating human disease phenotypes. In addition, the potential of human pluripotent stem cell (hPSC) technology in overcoming current model limitations is discussed, offering a promising avenue for studying GCK-related diseases at the molecular level. Ultimately, a deeper understanding of GCK's multifaceted role in glucose metabolism and its dysregulation in disease states holds implications for developing targeted therapeutic interventions for diabetes and related disorders.
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Affiliation(s)
- Yasmin Abu Aqel
- Laboratory of Pluripotent Stem Cell Disease Modeling, Translational Medicine Division, Research Branch, Sidra Medicine, P.O. Box 26999, Doha, Qatar
| | - Aldana Alnesf
- Laboratory of Pluripotent Stem Cell Disease Modeling, Translational Medicine Division, Research Branch, Sidra Medicine, P.O. Box 26999, Doha, Qatar
- College of Health and Life Sciences, Hamad Bin Khalifa University (HBKU), Qatar Foundation, Education City, Doha, Qatar
| | - Idil I Aigha
- Laboratory of Pluripotent Stem Cell Disease Modeling, Translational Medicine Division, Research Branch, Sidra Medicine, P.O. Box 26999, Doha, Qatar
| | - Zeyaul Islam
- Diabetes Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation (QF), PO Box 34110, Doha, Qatar
| | - Prasanna R Kolatkar
- College of Health and Life Sciences, Hamad Bin Khalifa University (HBKU), Qatar Foundation, Education City, Doha, Qatar
- Diabetes Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation (QF), PO Box 34110, Doha, Qatar
| | - Adrian Teo
- Stem Cells and Diabetes Laboratory, Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A*STAR), Proteos, Singapore, Singapore
- Department of Biochemistry and Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Precision Medicine Translational Research Programme (PM TRP), Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Essam M Abdelalim
- Laboratory of Pluripotent Stem Cell Disease Modeling, Translational Medicine Division, Research Branch, Sidra Medicine, P.O. Box 26999, Doha, Qatar.
- College of Health and Life Sciences, Hamad Bin Khalifa University (HBKU), Qatar Foundation, Education City, Doha, Qatar.
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Cho J, Horikawa Y, Oiwa Y, Hosomichi K, Yabe D, Imai T. Glucokinase Variant Proteins Are Resistant to Fasting-Induced Uridine Diphosphate Glucose-Dependent Degradation in Maturity-Onset Diabetes of the Young Type 2 Patients. Int J Mol Sci 2023; 24:15842. [PMID: 37958824 PMCID: PMC10649437 DOI: 10.3390/ijms242115842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 10/27/2023] [Accepted: 10/29/2023] [Indexed: 11/15/2023] Open
Abstract
We previously reported that glucokinase undergoes ubiquitination and subsequent degradation, a process mediated by cereblon, particularly in the presence of uridine diphosphate glucose (UDP-glucose). In this context, we hereby present evidence showcasing the resilience of variant glucokinase proteins of maturity-onset diabetes of the young type 2 (MODY2) against degradation and, concomitantly, their influence on insulin secretion, both in cell lines and in the afflicted MODY2 patient. Hence, glucose-1-phodphate promotes UDP-glucose production by UDP-glucose pyrophosphorylase 2; consequently, UDP-glucose-dependent glucokinase degradation may occur during fasting. Next, we analyzed glucokinase variant proteins from MODY2 or persistent hyperinsulinemic hypoglycemia in infancy (PHHI). Among the eleven MODY2 glucokinase-mutated proteins tested, those with a lower glucose-binding affinity exhibited resistance to UDP-glucose-dependent degradation. Conversely, the glucokinaseA456V-mutated protein from PHHI had a higher glucose affinity and was sensitive to UDP-glucose-dependent degradation. Furthermore, in vitro studies involving UDP-glucose-dependent glucokinase variant proteins and insulin secretion during fasting in Japanese MODY2 patients revealed a strong correlation and a higher coefficient of determination. This suggests that UDP-glucose-dependent glucokinase degradation plays a significant role in the pathogenesis of glucose-homeostasis-related hereditary diseases, such as MODY2 and PHHI.
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Affiliation(s)
- Jaeyong Cho
- Department of Chemical Biology, National Center for Geriatrics and Gerontology, Obu 474-8511, Japan; (J.C.); (Y.O.)
| | - Yukio Horikawa
- Departments of Diabetes, Endocrinology and Metabolism, Gifu University Graduate School of Medicine, Gifu 501-1194, Japan; (Y.H.); (D.Y.)
| | - Yuki Oiwa
- Department of Chemical Biology, National Center for Geriatrics and Gerontology, Obu 474-8511, Japan; (J.C.); (Y.O.)
| | - Kazuyoshi Hosomichi
- Laboratory of Computational Genomics, School of Life Science, Tokyo University of Pharmacy and Life Sciences, Tokyo 192-0392, Japan;
| | - Daisuke Yabe
- Departments of Diabetes, Endocrinology and Metabolism, Gifu University Graduate School of Medicine, Gifu 501-1194, Japan; (Y.H.); (D.Y.)
- Department of Rheumatology and Clinical Immunology, Gifu University Graduate School of Medicine, Gifu 501-1194, Japan
| | - Takeshi Imai
- Department of Chemical Biology, National Center for Geriatrics and Gerontology, Obu 474-8511, Japan; (J.C.); (Y.O.)
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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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Gersing S, Cagiada M, Gebbia M, Gjesing AP, Coté AG, Seesankar G, Li R, Tabet D, Weile J, Stein A, Gloyn AL, Hansen T, Roth FP, Lindorff-Larsen K, Hartmann-Petersen R. A comprehensive map of human glucokinase variant activity. Genome Biol 2023; 24:97. [PMID: 37101203 PMCID: PMC10131484 DOI: 10.1186/s13059-023-02935-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 04/10/2023] [Indexed: 04/28/2023] Open
Abstract
BACKGROUND Glucokinase (GCK) regulates insulin secretion to maintain appropriate blood glucose levels. Sequence variants can alter GCK activity to cause hyperinsulinemic hypoglycemia or hyperglycemia associated with GCK-maturity-onset diabetes of the young (GCK-MODY), collectively affecting up to 10 million people worldwide. Patients with GCK-MODY are frequently misdiagnosed and treated unnecessarily. Genetic testing can prevent this but is hampered by the challenge of interpreting novel missense variants. RESULT Here, we exploit a multiplexed yeast complementation assay to measure both hyper- and hypoactive GCK variation, capturing 97% of all possible missense and nonsense variants. Activity scores correlate with in vitro catalytic efficiency, fasting glucose levels in carriers of GCK variants and with evolutionary conservation. Hypoactive variants are concentrated at buried positions, near the active site, and at a region of known importance for GCK conformational dynamics. Some hyperactive variants shift the conformational equilibrium towards the active state through a relative destabilization of the inactive conformation. CONCLUSION Our comprehensive assessment of GCK variant activity promises to facilitate variant interpretation and diagnosis, expand our mechanistic understanding of hyperactive variants, and inform development of therapeutics targeting GCK.
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Affiliation(s)
- Sarah Gersing
- The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, 2200, Copenhagen, Denmark
| | - Matteo Cagiada
- The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, 2200, Copenhagen, Denmark
| | - Marinella Gebbia
- Donnelly Centre, University of Toronto, Toronto, ON, M5S 3E1, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON, M5S 1A8, Canada
- Lunenfeld-Tanenbaum Research Institute, Sinai Health, Toronto, ON, M5G 1X5, Canada
| | - Anette P Gjesing
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Atina G Coté
- Donnelly Centre, University of Toronto, Toronto, ON, M5S 3E1, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON, M5S 1A8, Canada
- Lunenfeld-Tanenbaum Research Institute, Sinai Health, Toronto, ON, M5G 1X5, Canada
| | - Gireesh Seesankar
- Donnelly Centre, University of Toronto, Toronto, ON, M5S 3E1, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON, M5S 1A8, Canada
- Lunenfeld-Tanenbaum Research Institute, Sinai Health, Toronto, ON, M5G 1X5, Canada
| | - Roujia Li
- Donnelly Centre, University of Toronto, Toronto, ON, M5S 3E1, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON, M5S 1A8, Canada
- Lunenfeld-Tanenbaum Research Institute, Sinai Health, Toronto, ON, M5G 1X5, Canada
- Department of Computer Science, University of Toronto, Toronto, ON, M5T 3A1, Canada
| | - Daniel Tabet
- Donnelly Centre, University of Toronto, Toronto, ON, M5S 3E1, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON, M5S 1A8, Canada
- Lunenfeld-Tanenbaum Research Institute, Sinai Health, Toronto, ON, M5G 1X5, Canada
- Department of Computer Science, University of Toronto, Toronto, ON, M5T 3A1, Canada
| | - Jochen Weile
- Donnelly Centre, University of Toronto, Toronto, ON, M5S 3E1, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON, M5S 1A8, Canada
- Lunenfeld-Tanenbaum Research Institute, Sinai Health, Toronto, ON, M5G 1X5, Canada
- Department of Computer Science, University of Toronto, Toronto, ON, M5T 3A1, Canada
| | - Amelie Stein
- The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, 2200, Copenhagen, Denmark
| | - Anna L Gloyn
- Division of Endocrinology, Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, USA
- Stanford Diabetes Research Center, Stanford University, Stanford, CA, USA
| | - Torben Hansen
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Frederick P Roth
- Donnelly Centre, University of Toronto, Toronto, ON, M5S 3E1, Canada.
- Department of Molecular Genetics, University of Toronto, Toronto, ON, M5S 1A8, Canada.
- Lunenfeld-Tanenbaum Research Institute, Sinai Health, Toronto, ON, M5G 1X5, Canada.
- Department of Computer Science, University of Toronto, Toronto, ON, M5T 3A1, Canada.
| | - Kresten Lindorff-Larsen
- The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, 2200, Copenhagen, Denmark.
| | - Rasmus Hartmann-Petersen
- The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, 2200, Copenhagen, Denmark.
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Dai T, Yang Y, Zhang J, Ma X, Chen L, Zhang C, Lv S, Li L, Tang R, Zhen N, Lu W, Li C, Hu R, Xiao Y, Dong Z. GCK exonic mutations induce abnormal biochemical activities and result in GCK-MODY. Front Genet 2023; 14:1120153. [PMID: 37082200 PMCID: PMC10110986 DOI: 10.3389/fgene.2023.1120153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Accepted: 03/21/2023] [Indexed: 04/07/2023] Open
Abstract
Objective: Glucokinase-maturity-onset diabetes of the young (GCK-MODY; MODY2) is a rare genetic disorder caused by mutations in the glucokinase (GCK) gene. It is often under- or misdiagnosed in clinical practice, but correct diagnosis can be facilitated by genetic testing. In this study, we examined the genes of three patients diagnosed with GCK-MODY and tested their biochemical properties, such as protein stability and half-life, to explore the function of the mutant proteins and identify the pathogenic mechanism of GCK-MODY.Methods: Three patients with increased blood glucose levels were diagnosed with MODY2 according to the diagnostic guidelines of GCK-MODY proposed by the International Society for Pediatric and Adolescent Diabetes (ISPAD) in 2018. Next-generation sequencing (whole exome detection) was performed to detect gene mutations. The GCK gene and its mutations were introduced into the pCDNA3.0 and pGEX-4T-1 vectors. Following protein purification, enzyme activity assay, and protein immunoblotting, the enzyme activity of GCK was determined, along with the ubiquitination level of the mutant GCK protein.Results: Genetic testing revealed three mutations in the GCK gene of the three patients, including c.574C>T (p.R192W), c.758G>A (p.C253Y), and c.794G>A (p.G265D). The biochemical characteristics of the protein encoded by wild-type GCK and mutant GCK were different, compared to wild-type GCK, the enzyme activity encoded by the mutant GCK was reduced, suggesting thermal instability of the mutant GST-GCK. The protein stability and expression levels of the mutant GCK were reduced, and the enzyme activity of GCK was negatively correlated with the levels of fasting blood glucose and HbA1c. In addition, ubiquitination of the mutant GCK protein was higher than that of the wild-type, suggesting a higher degradation rate of mutant GCK than WT-GCK.Conclusion:GCK mutations lead to changes in the biochemical characteristics of its encoded proteins. The enzyme activities, protein expression, and protein stability of GCK may be reduced in patients with GCK gene mutations, which further causes glucose metabolism disorders and induces MODY2.
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Affiliation(s)
- Tongtong Dai
- Department of Pediatrics, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Yun Yang
- School of Medicine, Guizhou University, Guiyang, China
| | - Juanjuan Zhang
- Department of Pediatrics, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Xiaoyu Ma
- Department of Pediatrics, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Lifen Chen
- Department of Pediatrics, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Caiping Zhang
- Department of Pediatrics, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Sheng Lv
- Department of Pediatrics, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Lin Li
- Department of Pediatrics, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Renqiao Tang
- Department of Pediatrics, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Ni Zhen
- Department of Pediatrics, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Wenli Lu
- Department of Pediatrics, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Chuanyin Li
- Cancer Center, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Ronggui Hu
- State Key Laboratory of Molecular Biology, Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, China
| | - Yuan Xiao
- Department of Pediatrics, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Zhiya Dong
- Department of Pediatrics, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
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Jung SY, Sobel EM, Pellegrini M, Yu H, Papp JC. Synergistic Effects of Genetic Variants of Glucose Homeostasis and Lifelong Exposures to Cigarette Smoking, Female Hormones, and Dietary Fat Intake on Primary Colorectal Cancer Development in African and Hispanic/Latino American Women. Front Oncol 2021; 11:760243. [PMID: 34692549 PMCID: PMC8529283 DOI: 10.3389/fonc.2021.760243] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 09/22/2021] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Disparities in cancer genomic science exist among racial/ethnic minorities. Particularly, African American (AA) and Hispanic/Latino American (HA) women, the 2 largest minorities, are underrepresented in genetic/genome-wide studies for cancers and their risk factors. We conducted on AA and HA postmenopausal women a genomic study for insulin resistance (IR), the main biologic mechanism underlying colorectal cancer (CRC) carcinogenesis owing to obesity. METHODS With 780 genome-wide IR-specific single-nucleotide polymorphisms (SNPs) among 4,692 AA and 1,986 HA women, we constructed a CRC-risk prediction model. Along with these SNPs, we incorporated CRC-associated lifestyles in the model of each group and detected the topmost influential genetic and lifestyle factors. Further, we estimated the attributable risk of the topmost risk factors shared by the groups to explore potential factors that differentiate CRC risk between these groups. RESULTS In both groups, we detected IR-SNPs in PCSK1 (in AA) and IFT172, GCKR, and NRBP1 (in HA) and risk lifestyles, including long lifetime exposures to cigarette smoking and endogenous female hormones and daily intake of polyunsaturated fatty acids (PFA), as the topmost predictive variables for CRC risk. Combinations of those top genetic- and lifestyle-markers synergistically increased CRC risk. Of those risk factors, dietary PFA intake and long lifetime exposure to female hormones may play a key role in mediating racial disparity of CRC incidence between AA and HA women. CONCLUSIONS Our results may improve CRC risk prediction performance in those medically/scientifically underrepresented groups and lead to the development of genetically informed interventions for cancer prevention and therapeutic effort, thus contributing to reduced cancer disparities in those minority subpopulations.
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Affiliation(s)
- Su Yon Jung
- Translational Sciences Section, Jonsson Comprehensive Cancer Center, School of Nursing, University of California, Los Angeles, Los Angeles, CA, United States
| | - Eric M. Sobel
- Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
- Department of Computational Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
| | - Matteo Pellegrini
- Department of Molecular, Cell and Developmental Biology, Life Sciences Division, University of California, Los Angeles, Los Angeles, CA, United States
| | - Herbert Yu
- Cancer Epidemiology Program, University of Hawaii Cancer Center, Honolulu, HI, United States
| | - Jeanette C. Papp
- Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
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A Comprehensive Analysis of Hungarian MODY Patients-Part II: Glucokinase MODY Is the Most Prevalent Subtype Responsible for about 70% of Confirmed Cases. Life (Basel) 2021; 11:life11080771. [PMID: 34440516 PMCID: PMC8400228 DOI: 10.3390/life11080771] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 07/20/2021] [Accepted: 07/27/2021] [Indexed: 01/22/2023] Open
Abstract
MODY2 is caused by heterozygous inactivating mutations in the glucokinase (GCK) gene that result in persistent, stable and mild fasting hyperglycaemia (5.6–8.0 mmol/L, glycosylated haemoglobin range of 5.6–7.3%). Patients with GCK mutations usually do not require any drug treatment, except during pregnancy. The GCK gene is considered to be responsible for about 20% of all MODY cases, transcription factors for 67% and other genes for 13% of the cases. Based on our findings, GCK and HNF1A mutations together are responsible for about 90% of the cases in Hungary, this ratio being higher than the 70% reported in the literature. More than 70% of these patients have a mutation in the GCK gene, this means that GCK-MODY is the most prevalent form of MODY in Hungary. In the 91 index patients and their 72 family members examined, we have identified a total of 65 different pathogenic (18) and likely pathogenic (47) GCK mutations of which 28 were novel. In two families, de novo GCK mutations were detected. About 30% of the GCK-MODY patients examined were receiving unnecessary OAD or insulin therapy at the time of requesting their genetic testing, therefore the importance of having a molecular genetic diagnosis can lead to a major improvement in their quality of life.
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Ivanoshchuk DE, Shakhtshneider EV, Rymar OD, Ovsyannikova AK, Mikhailova SV, Fishman VS, Valeev ES, Orlov PS, Voevoda MI. The Mutation Spectrum of Maturity Onset Diabetes of the Young (MODY)-Associated Genes among Western Siberia Patients. J Pers Med 2021; 11:57. [PMID: 33477506 PMCID: PMC7831070 DOI: 10.3390/jpm11010057] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 01/13/2021] [Accepted: 01/13/2021] [Indexed: 12/13/2022] Open
Abstract
Maturity onset diabetes of the young (MODY) is a congenital form of diabetes characterized by onset at a young age and a primary defect in pancreatic-β-cell function. Currently, 14 subtypes of MODY are known, and each is associated with mutations in a specific gene: HNF4A, GCK, HNF1A, PDX1, HNF1B, NEUROD1, KLF11, CEL, PAX4, INS, BLK, KCNJ11, ABCC8, and APPL1. The most common subtypes of MODY are associated with mutations in the genes GCK, HNF1A, HNF4A, and HNF1B. Among them, up to 70% of cases are caused by mutations in GCK and HNF1A. Here, an analysis of 14 MODY genes was performed in 178 patients with a MODY phenotype in Western Siberia. Multiplex ligation-dependent probe amplification analysis of DNA samples from 50 randomly selected patients without detectable mutations did not reveal large rearrangements in the MODY genes. In 38 patients (37% males) among the 178 subjects, mutations were identified in HNF4A, GCK, HNF1A, and ABCC8. We identified novel potentially causative mutations p.Lys142*, Leu146Val, Ala173Glnfs*30, Val181Asp, Gly261Ala, IVS7 c.864 -1G>T, Cys371*, and Glu443Lys in GCK and Ser6Arg, IVS 2 c.526 +1 G>T, IVS3 c.713 +2 T>A, and Arg238Lys in HNF1A.
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Affiliation(s)
- Dinara E. Ivanoshchuk
- Federal Research Center Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences (SB RAS), Prospekt Lavrentyeva 10, 630090 Novosibirsk, Russia; (E.V.S.); (S.V.M.); (V.S.F.); (E.S.V.); (P.S.O.); (M.I.V.)
- Institute of Internal and Preventive Medicine—Branch of Institute of Cytology and Genetics, SB RAS, Bogatkova Str. 175/1, 630004 Novosibirsk, Russia; (O.D.R.); (A.K.O.)
| | - Elena V. Shakhtshneider
- Federal Research Center Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences (SB RAS), Prospekt Lavrentyeva 10, 630090 Novosibirsk, Russia; (E.V.S.); (S.V.M.); (V.S.F.); (E.S.V.); (P.S.O.); (M.I.V.)
- Institute of Internal and Preventive Medicine—Branch of Institute of Cytology and Genetics, SB RAS, Bogatkova Str. 175/1, 630004 Novosibirsk, Russia; (O.D.R.); (A.K.O.)
| | - Oksana D. Rymar
- Institute of Internal and Preventive Medicine—Branch of Institute of Cytology and Genetics, SB RAS, Bogatkova Str. 175/1, 630004 Novosibirsk, Russia; (O.D.R.); (A.K.O.)
| | - Alla K. Ovsyannikova
- Institute of Internal and Preventive Medicine—Branch of Institute of Cytology and Genetics, SB RAS, Bogatkova Str. 175/1, 630004 Novosibirsk, Russia; (O.D.R.); (A.K.O.)
| | - Svetlana V. Mikhailova
- Federal Research Center Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences (SB RAS), Prospekt Lavrentyeva 10, 630090 Novosibirsk, Russia; (E.V.S.); (S.V.M.); (V.S.F.); (E.S.V.); (P.S.O.); (M.I.V.)
| | - Veniamin S. Fishman
- Federal Research Center Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences (SB RAS), Prospekt Lavrentyeva 10, 630090 Novosibirsk, Russia; (E.V.S.); (S.V.M.); (V.S.F.); (E.S.V.); (P.S.O.); (M.I.V.)
| | - Emil S. Valeev
- Federal Research Center Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences (SB RAS), Prospekt Lavrentyeva 10, 630090 Novosibirsk, Russia; (E.V.S.); (S.V.M.); (V.S.F.); (E.S.V.); (P.S.O.); (M.I.V.)
| | - Pavel S. Orlov
- Federal Research Center Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences (SB RAS), Prospekt Lavrentyeva 10, 630090 Novosibirsk, Russia; (E.V.S.); (S.V.M.); (V.S.F.); (E.S.V.); (P.S.O.); (M.I.V.)
- Institute of Internal and Preventive Medicine—Branch of Institute of Cytology and Genetics, SB RAS, Bogatkova Str. 175/1, 630004 Novosibirsk, Russia; (O.D.R.); (A.K.O.)
| | - Mikhail I. Voevoda
- Federal Research Center Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences (SB RAS), Prospekt Lavrentyeva 10, 630090 Novosibirsk, Russia; (E.V.S.); (S.V.M.); (V.S.F.); (E.S.V.); (P.S.O.); (M.I.V.)
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9
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Vincent O, Gutierrez-Nogués A, Trejo-Herrero A, Navas MA. A novel reverse two-hybrid method for the identification of missense mutations that disrupt protein-protein binding. Sci Rep 2020; 10:21043. [PMID: 33273586 PMCID: PMC7713115 DOI: 10.1038/s41598-020-77992-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Accepted: 11/19/2020] [Indexed: 01/26/2023] Open
Abstract
The reverse two-hybrid system is a powerful method to select mutations that disrupt the interaction between two proteins and therefore to identify the residues involved in this interaction. However, the usefulness of this technique has been limited by its relative complexity when compared to the classical two-hybrid system, since an additional selection step is required to eliminate the high background of uninformative truncation mutants. We have developed a new method that combines the classical and reverse two-hybrid systems to select loss-of-binding missense mutations in a single step. The strategy used to select against truncation mutants is based on the two-hybrid interaction between a C-terminal fusion peptide and the Tsg101 protein. We have applied this method to identify mutations in human glucokinase (GK) that disrupt glucokinase regulatory protein (GKRP) binding. Our results indicate that this method is very efficient and eliminates all the truncation mutants and false positives. The mutated residues identified in GK are involved in the GKRP binding interface or in stabilizing the super-open conformation of GK that binds GKRP. This technique offers an improvement over existing methods in terms of speed, efficiency and simplicity and can be used to study any detectable protein interaction in the two-hybrid system.
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Affiliation(s)
- Olivier Vincent
- Instituto de Investigaciones Biomédicas Alberto Sols CSIC-UAM, 28029, Madrid, Spain.
| | - Angel Gutierrez-Nogués
- Departamento de Bioquímica y Biología Molecular, Facultad de Medicina, Universidad Complutense de Madrid, Madrid, Spain
| | - Adrían Trejo-Herrero
- Departamento de Bioquímica y Biología Molecular, Facultad de Medicina, Universidad Complutense de Madrid, Madrid, Spain
| | - María-Angeles Navas
- Departamento de Bioquímica y Biología Molecular, Facultad de Medicina, Universidad Complutense de Madrid, Madrid, Spain.
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10
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Liang H, Zhang Y, Li M, Yan J, Yang D, Luo S, Zheng X, Yang G, Li Z, Xu W, Groop L, Weng J. Recognition of maturity-onset diabetes of the young in China. J Diabetes Investig 2020; 12:501-509. [PMID: 32741144 PMCID: PMC8015824 DOI: 10.1111/jdi.13378] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 07/15/2020] [Accepted: 07/27/2020] [Indexed: 12/14/2022] Open
Abstract
Aims/Introduction Given that mutations related to maturity‐onset diabetes of the young (MODY) are rarely found in Chinese populations, we aim to characterize the mutation spectrum of MODY pedigrees. Materials and Methods Maturity‐onset diabetes of the young candidate gene‐ or exome‐targeted capture sequencing was carried out in 76 probands from unrelated families fulfilling the clinical diagnostic criteria for MODY. MAF <0.01 in the GnomAD or ExAC database was used to filter significant variants. Sanger sequencing was then carried out to validate findings. Function prediction by SIFT, PolyPhen‐2 and PROVEAN or CADD was carried out in missense mutations. Results A total of 32 mutations in six genes were identified in 31 families, accounting for 40.79% of the potential MODY families. The MODY subtype detection rate was 18.42% for GCK, 15.79% for HNF1A, 2.63% for HNF4A, and 1.32% for KLF11, PAX4 and NEUROG3. Seven nonsense/frameshift mutations and four missense mutations with damaging prediction were newly identified novel mutations. The clinical features of MODY2, MODY3/1 and MODYX are similar to previous reports. Clinical phenotype of NEUROG3 p.Arg55Glufs*23 is characterized by hyperglycemia and mild intermittent abdominal pain. Conclusions This study adds to the emerging pattern of MODY epidemiology that the proportion of MODY explained by known pathogenic genes is higher than that previously reported, and found NEUROG3 as a new causative gene for MODY.
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Affiliation(s)
- Hua Liang
- Department of Endocrinology and Metabolism, The Third Affiliated Hospital of Sun Yat-sen University, Guangdong Provincial Key Laboratory of Diabetology, Guangzhou, China
| | - Yanan Zhang
- Department of Infertility and Sexual Medicine, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China
| | - Maixinyue Li
- Department of Clinical Laboratory, Nanning Children's Hospital, Nanning, China
| | - Jinhua Yan
- Department of Endocrinology and Metabolism, The Third Affiliated Hospital of Sun Yat-sen University, Guangdong Provincial Key Laboratory of Diabetology, Guangzhou, China
| | - Daizhi Yang
- Department of Endocrinology and Metabolism, The Third Affiliated Hospital of Sun Yat-sen University, Guangdong Provincial Key Laboratory of Diabetology, Guangzhou, China
| | - Sihui Luo
- Division of Life Sciences and Medicine, Department of Endocrinology, The First Affiliated Hospital, University of Science and Technology of China, Hefei, China
| | - Xueying Zheng
- Division of Life Sciences and Medicine, Department of Endocrinology, The First Affiliated Hospital, University of Science and Technology of China, Hefei, China
| | - Guoqing Yang
- Department of Endocrinology, Chinese PLA General Hospital, Beijing, China
| | - Zhuo Li
- Department of Endocrinology and Metabolism, The Third Affiliated Hospital of Sun Yat-sen University, Guangdong Provincial Key Laboratory of Diabetology, Guangzhou, China
| | - Wen Xu
- Department of Endocrinology and Metabolism, The Third Affiliated Hospital of Sun Yat-sen University, Guangdong Provincial Key Laboratory of Diabetology, Guangzhou, China
| | - Leif Groop
- Department of Clinical Sciences, Lund University Diabetes Center, Lund University, Malmö, Sweden
| | - Jianping Weng
- Department of Endocrinology and Metabolism, The Third Affiliated Hospital of Sun Yat-sen University, Guangdong Provincial Key Laboratory of Diabetology, Guangzhou, China.,Division of Life Sciences and Medicine, Department of Endocrinology, The First Affiliated Hospital, University of Science and Technology of China, Hefei, China
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11
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Affiliation(s)
- Miriam S Udler
- From the Departments of Medicine (M.S.U., C.E.P.) and Pathology (C.A.A.-T.), Massachusetts General Hospital, and the Departments of Medicine (M.S.U., C.E.P.) and Pathology (C.A.A.-T.), Harvard Medical School - both in Boston
| | - Camille E Powe
- From the Departments of Medicine (M.S.U., C.E.P.) and Pathology (C.A.A.-T.), Massachusetts General Hospital, and the Departments of Medicine (M.S.U., C.E.P.) and Pathology (C.A.A.-T.), Harvard Medical School - both in Boston
| | - Christina A Austin-Tse
- From the Departments of Medicine (M.S.U., C.E.P.) and Pathology (C.A.A.-T.), Massachusetts General Hospital, and the Departments of Medicine (M.S.U., C.E.P.) and Pathology (C.A.A.-T.), Harvard Medical School - both in Boston
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12
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Shidler KL, Letourneau LR, Novak LM. Uncommon Presentations of Diabetes: Zebras in the Herd. Clin Diabetes 2020; 38:78-92. [PMID: 31975755 PMCID: PMC6969666 DOI: 10.2337/cd19-0019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The majority of patients with diabetes are diagnosed as having either type 1 or type 2 diabetes. However, when encountered in clinical practice, some patients may not match the classic diagnostic criteria or expected clinical presentation for either type of the disease. Latent autoimmune, ketosis-prone, and monogenic diabetes are nonclassical forms of diabetes that are often misdiagnosed as either type 1 or type 2 diabetes. Recognizing the distinguishing clinical characteristics and understanding the diagnostic criteria for each will lead to appropriate treatment, facilitate personalized medicine, and improve patient outcomes.
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Affiliation(s)
- Karen L. Shidler
- North Central Indiana Area Health Education Center, Rochester, IN
| | | | - Lucia M. Novak
- Riverside Diabetes Center, Riverside Medical Associates, Riverdale, MD
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13
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Jang HB, Go MJ, Park SI, Lee HJ, Cho SB. Chronic heavy alcohol consumption influences the association between genetic variants of GCK or INSR and the development of diabetes in men: A 12-year follow-up study. Sci Rep 2019; 9:20029. [PMID: 31882596 PMCID: PMC6934767 DOI: 10.1038/s41598-019-56011-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Accepted: 12/03/2019] [Indexed: 12/17/2022] Open
Abstract
Chronic heavy alcohol consumption is a risk factor for diabetes, which is characterized by impaired β-cell function and insulin resistance. We aimed to determine whether the longitudinal associations between genetic variants of glucokinase (GCK) and insulin receptor (INSR) and the risk of developing diabetes were influenced by chronic heavy alcohol consumption. Data were obtained from the Korean Genome and Epidemiology Study. To identify candidate variants, 1,520 subjects (726 non-drinkers and 794 heavy drinkers) were included in the baseline cross-sectional study. After excluding patients with diabetes at baseline and those with insufficient data on diabetes incidence, prospective analyses were conducted in 773 subjects (353 non-drinkers and 420 heavy drinkers). In the baseline cross-sectional study, one SNP (rs758989) in GCK and four SNPs (rs7245757, rs1035942, rs1035940, and rs2042901) in INSR were selected as candidate SNPs that interact with alcohol to affect prediabetes and diabetes. We identified that these GCK and INSR polymorphisms are affected by chronic heavy alcohol consumption and have an effect on the incidence of diabetes. The incidence of diabetes was increased in chronic heavy alcohol drinkers carrying the C allele of GCK compared with never-drinkers with the C allele (HR, 2.15; 95% CI 1.30-3.57), and was increased in chronic heavy alcohol drinkers who were not carrying the INSR haplotype (-/-) compared with never-drinkers carrying the AACT haplotype (HR, 1.98; 95% CI 1.24-3.18). Moreover, we observed that the aggravating effects on the late insulin secretion (I/G120 and I/G AUC 60-120) in individuals who were chronic heavy drinkers with C allele of GCK. In the INSR haplotype, chronic heavy drinkers not carrying AACT were associated with lower disposition index. These results potentially suggest that chronic heavy alcohol consumption induce β-cell dysfunction partially mediated by decreased GCK expression or decline of insulin sensitivity via inhibition of INSR, thereby contributing to the development of diabetes.
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Affiliation(s)
- Han Byul Jang
- Center for Biomedical Science, Korea National Institute of Health, Cheongju, Chungcheongbuk-do, Republic of Korea
| | - Min Jin Go
- Center for Genome Science, Korea National Institute of Health, Cheongju, Chungcheongbuk-do, Republic of Korea
| | - Sang Ick Park
- Center for Biomedical Science, Korea National Institute of Health, Cheongju, Chungcheongbuk-do, Republic of Korea
| | - Hye-Ja Lee
- Center for Biomedical Science, Korea National Institute of Health, Cheongju, Chungcheongbuk-do, Republic of Korea.
| | - Seong Beom Cho
- Center for Genome Science, Korea National Institute of Health, Cheongju, Chungcheongbuk-do, Republic of Korea.
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14
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Dwulet JM, Ludin NWF, Piscopio RA, Schleicher WE, Moua O, Westacott MJ, Benninger RKP. How Heterogeneity in Glucokinase and Gap-Junction Coupling Determines the Islet [Ca 2+] Response. Biophys J 2019; 117:2188-2203. [PMID: 31753287 PMCID: PMC6895742 DOI: 10.1016/j.bpj.2019.10.037] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 09/20/2019] [Accepted: 10/25/2019] [Indexed: 11/24/2022] Open
Abstract
Understanding how cell subpopulations in a tissue impact overall system function is challenging. There is extensive heterogeneity among insulin-secreting β-cells within islets of Langerhans, including their insulin secretory response and gene expression profile, and this heterogeneity can be altered in diabetes. Several studies have identified variations in nutrient sensing between β-cells, including glucokinase (GK) levels, mitochondrial function, or expression of genes important for glucose metabolism. Subpopulations of β-cells with defined electrical properties can disproportionately influence islet-wide free-calcium activity ([Ca2+]) and insulin secretion via gap-junction electrical coupling. However, it is poorly understood how subpopulations of β-cells with altered glucose metabolism may impact islet function. To address this, we utilized a multicellular computational model of the islet in which a population of cells deficient in GK activity and glucose metabolism was imposed on the islet or in which β-cells were heterogeneous in glucose metabolism and GK kinetics were altered. This included simulating GK gene (GCK) mutations that cause monogenic diabetes. We combined these approaches with experimental models in which gck was genetically deleted in a population of cells or GK was pharmacologically inhibited. In each case, we modulated gap-junction electrical coupling. Both the simulated islet and the experimental system required 30-50% of the cells to have near-normal glucose metabolism, fewer than cells with normal KATP conductance. Below this number, the islet lacked any glucose-stimulated [Ca2+] elevations. In the absence of electrical coupling, the change in [Ca2+] was more gradual. As such, electrical coupling allows a large minority of cells with normal glucose metabolism to promote glucose-stimulated [Ca2+]. If insufficient numbers of cells are present, which we predict can be caused by a subset of GCK mutations that cause monogenic diabetes, electrical coupling exacerbates [Ca2+] suppression. This demonstrates precisely how metabolically heterogeneous β-cell populations interact to impact islet function.
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Affiliation(s)
- JaeAnn M Dwulet
- Department of Bioengineering, University of Colorado, Aurora, Colorado
| | - Nurin W F Ludin
- Department of Bioengineering, University of Colorado, Aurora, Colorado
| | - Robert A Piscopio
- Department of Bioengineering, University of Colorado, Aurora, Colorado
| | | | - Ong Moua
- Department of Bioengineering, University of Colorado, Aurora, Colorado
| | | | - Richard K P Benninger
- Department of Bioengineering, University of Colorado, Aurora, Colorado; Barbara Davis Center for Childhood Diabetes, Anschutz Medical Campus, University of Colorado, Aurora, Colorado.
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15
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Wang Z, Diao C, Liu Y, Li M, Zheng J, Zhang Q, Yu M, Zhang H, Ping F, Li M, Xiao X. Identification and functional analysis of GCK gene mutations in 12 Chinese families with hyperglycemia. J Diabetes Investig 2019; 10:963-971. [PMID: 30592380 PMCID: PMC6626954 DOI: 10.1111/jdi.13001] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Revised: 12/22/2018] [Accepted: 12/26/2018] [Indexed: 01/07/2023] Open
Abstract
AIMS/INTRODUCTION To investigate the clinical and genetic characteristics of Chinese patients with a phenotype consistent with maturity-onset diabetes of the young type 2 and explore the pathogenic mechanism of their hyperglycemia. MATERIALS AND METHODS We studied 12 probands and their extended families referred to our center for screening mutations in the glucokinase gene (GCK). Clinical data were collected and genetic analysis was carried out. The recombinant wild-type and mutant glucokinase were generated in Escherichia coli. The kinetic parameters and thermal stability of the enzymes were determined in vitro. RESULTS In the 12 families, 11 GCK mutations (R43C, T168A, K169N, R191W, Y215X, E221K, M235T, R250H, W257X, G261R and A379E) and one variant of uncertain significance (R275H) were identified. R191W was detected in two unrelated families. Of the 11 GCK mutations, three mutations (c.507G>C, K169N; c.645C>A, Y215X; c.771G>A, W257X; NM_000162.3, NP_000153.1) are novel. Basic kinetics analysis explained the pathogenicity of the five mutants (R43C, K169N, R191W, E221K and A379E), which showed reduced enzyme activity with relative activity indexes between ~0.001 and 0.5 compared with the wild-type (1.0). In addition, the thermal stabilities of these five mutants were also decreased to varying degrees. However, for R250H and R275H, there was no significant difference in the enzyme activity and thermal stability between the mutants and the wild type. CONCLUSIONS We have identified 11 GCK mutations and one variant of uncertain significance in 12 Chinese families with hyperglycemia. For five GCK mutations (R43C, K169N, R191W, E221K and A379E), the changes in enzyme kinetics and thermostability might be the pathogenic mechanisms by which mutations cause hyperglycemia.
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Affiliation(s)
- Zhixin Wang
- Key Laboratory of EndocrinologyTranslational Medicine CenterMinistry of HealthDepartment of EndocrinologyPeking Union Medical College HospitalDiabetes Research Center of Chinese Academy of Medical Sciences & Peking Union Medical CollegeBeijingChina
- Present address:
Department of EndocrinologyBeijing Jishuitan HospitalBeijingChina
| | - Chengming Diao
- Key Laboratory of EndocrinologyTranslational Medicine CenterMinistry of HealthDepartment of EndocrinologyPeking Union Medical College HospitalDiabetes Research Center of Chinese Academy of Medical Sciences & Peking Union Medical CollegeBeijingChina
| | - Yijing Liu
- Key Laboratory of EndocrinologyTranslational Medicine CenterMinistry of HealthDepartment of EndocrinologyPeking Union Medical College HospitalDiabetes Research Center of Chinese Academy of Medical Sciences & Peking Union Medical CollegeBeijingChina
| | - Mingmin Li
- Key Laboratory of EndocrinologyTranslational Medicine CenterMinistry of HealthDepartment of EndocrinologyPeking Union Medical College HospitalDiabetes Research Center of Chinese Academy of Medical Sciences & Peking Union Medical CollegeBeijingChina
| | - Jia Zheng
- Key Laboratory of EndocrinologyTranslational Medicine CenterMinistry of HealthDepartment of EndocrinologyPeking Union Medical College HospitalDiabetes Research Center of Chinese Academy of Medical Sciences & Peking Union Medical CollegeBeijingChina
| | - Qian Zhang
- Key Laboratory of EndocrinologyTranslational Medicine CenterMinistry of HealthDepartment of EndocrinologyPeking Union Medical College HospitalDiabetes Research Center of Chinese Academy of Medical Sciences & Peking Union Medical CollegeBeijingChina
| | - Miao Yu
- Key Laboratory of EndocrinologyTranslational Medicine CenterMinistry of HealthDepartment of EndocrinologyPeking Union Medical College HospitalDiabetes Research Center of Chinese Academy of Medical Sciences & Peking Union Medical CollegeBeijingChina
| | - Huabing Zhang
- Key Laboratory of EndocrinologyTranslational Medicine CenterMinistry of HealthDepartment of EndocrinologyPeking Union Medical College HospitalDiabetes Research Center of Chinese Academy of Medical Sciences & Peking Union Medical CollegeBeijingChina
| | - Fan Ping
- Key Laboratory of EndocrinologyTranslational Medicine CenterMinistry of HealthDepartment of EndocrinologyPeking Union Medical College HospitalDiabetes Research Center of Chinese Academy of Medical Sciences & Peking Union Medical CollegeBeijingChina
| | - Ming Li
- Key Laboratory of EndocrinologyTranslational Medicine CenterMinistry of HealthDepartment of EndocrinologyPeking Union Medical College HospitalDiabetes Research Center of Chinese Academy of Medical Sciences & Peking Union Medical CollegeBeijingChina
| | - Xinhua Xiao
- Key Laboratory of EndocrinologyTranslational Medicine CenterMinistry of HealthDepartment of EndocrinologyPeking Union Medical College HospitalDiabetes Research Center of Chinese Academy of Medical Sciences & Peking Union Medical CollegeBeijingChina
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16
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Siddiqui S, Waghdhare S, Gopi S, Bhargava A, Panda M, Radha V, Mohan V, Dubey S, Jha S. GCK Gene Screening and Association of GCK Variants With Gestational Diabetes in North Indian Population. CLINICAL MEDICINE INSIGHTS-ENDOCRINOLOGY AND DIABETES 2018; 11:1179551418806896. [PMID: 30386132 PMCID: PMC6204622 DOI: 10.1177/1179551418806896] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 09/20/2018] [Indexed: 11/23/2022]
Abstract
Background: GCK gene variants have been reported to be associated with gestational diabetes mellitus (GDM) in the Caucasian population. There are no reports exploring this association in the Indian population. Methods: This cross-sectional study included subjects from Max Super Speciality Hospital, New Delhi, India, over a span of 6 months. Females diagnosed with GDM as per the International Association of the Diabetes and Pregnancy Study Groups (IADPSG) criteria were enrolled. Direct gene sequencing was performed to screen all 10 exons and promoter region of GCK gene. Results: Out of the total 1000 females screened, 154 subjects had any degree of hyperglycemia. GCK gene screening was done and we observed 11 variants in 80.4% (41/51) of the GDM subset and 89.6% (43/48) of the controls. Allele frequencies of observed variants were not different between the control subjects (12.5%) and those diagnosed with GDM (8.4%). Conclusion: To the best of our knowledge, this is the first report from north India exploring association of GCK variants with GDM and we do not observe any association of GCK variants with GDM in our study population. CTRI Registration No: CTRI/2017/07/008964
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Affiliation(s)
- Samreen Siddiqui
- Institute of Endocrinology, Diabetes & Metabolism, Max Healthcare Institute Ltd., New Delhi, India.,Amity Institute of Virology and Immunology, Amity University Uttar Pradesh (AUUP), Noida, India
| | - Swati Waghdhare
- Institute of Endocrinology, Diabetes & Metabolism, Max Healthcare Institute Ltd., New Delhi, India
| | - Sundaramoorthy Gopi
- Madras Diabetes Research Foundation, ICMR Centre for Advanced Research on Diabetes, Chennai, India
| | - Amit Bhargava
- Institute of Endocrinology, Diabetes & Metabolism, Max Healthcare Institute Ltd., New Delhi, India
| | - Manju Panda
- Institute of Endocrinology, Diabetes & Metabolism, Max Healthcare Institute Ltd., New Delhi, India
| | - Venkatesan Radha
- Madras Diabetes Research Foundation, ICMR Centre for Advanced Research on Diabetes, Chennai, India
| | - Viswanathan Mohan
- Madras Diabetes Research Foundation, ICMR Centre for Advanced Research on Diabetes, Chennai, India.,Dr. Mohan's Diabetes Specialities Centre, WHO Collaborating Centre for Non Communicable Diseases Prevention & Control, IDF Centre of Excellence in Diabetes Care, Chennai, India
| | - Shweta Dubey
- Amity Institute of Virology and Immunology, Amity University Uttar Pradesh (AUUP), Noida, India
| | - Sujeet Jha
- Institute of Endocrinology, Diabetes & Metabolism, Max Healthcare Institute Ltd., New Delhi, India
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17
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Vadakedath S, Kandi V. Probable Potential Role of Urate Transporter Genes in the Development of Metabolic Disorders. Cureus 2018; 10:e2382. [PMID: 29850377 PMCID: PMC5973493 DOI: 10.7759/cureus.2382] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Metabolic disorders are a group of interrelated conditions which increases the risk of developing heart diseases, stroke, and diabetes. These usually occur as a consequence of deficiency of enzymes involved in biochemical reactions in the body. The dietary habits, lack of physical exercise, stress, and genetic susceptibility leads to an increased risk of developing metabolic disorders. A diet rich in processed food items containing high calories aggravates the production of a purine metabolite, the uric acid (UA). UA functions as an antioxidant, protects against inflammation, aging, and cancer. It exists as urate ions in the circulation and blood level of UA is maintained by a balance between its production in the liver and its excretion by the renal tubules. The regular excretion of UA through the kidneys is necessary to maintain optimum blood levels of UA (3-7 mg/dl). There are various transporters of uric acid present around the renal tubules, which help in reabsorption of UA into the blood. These urate transporters (UT) are proteins coded in the genes. Mutations in these genes may prompt disturbances in UA reabsorption, and could lead to the development of hyperuricaemia, insulin resistance, endothelial dysfunction, diabetes and other metabolic diseases. This paper reviews eight such genes coding for UTs and attempts to unravel the link between the activities of UA, UTs, and the consequences during mutations in the genes coding for the UTs in the development of metabolic disorders. The genes reviewed included SLC2A9, SLC17A1, SLC22A12, SLC16A9, GCKR, LRRC16A, PDZK1, and ABCG2.
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18
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Johansson BB, Fjeld K, Solheim MH, Shirakawa J, Zhang E, Keindl M, Hu J, Lindqvist A, Døskeland A, Mellgren G, Flatmark T, Njølstad PR, Kulkarni RN, Wierup N, Aukrust I, Bjørkhaug L. Nuclear import of glucokinase in pancreatic beta-cells is mediated by a nuclear localization signal and modulated by SUMOylation. Mol Cell Endocrinol 2017. [PMID: 28648619 DOI: 10.1016/j.mce.2017.06.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The localization of glucokinase in pancreatic beta-cell nuclei is a controversial issue. Although previous reports suggest such a localization, the mechanism for its import has so far not been identified. Using immunofluorescence, subcellular fractionation and mass spectrometry, we present evidence in support of glucokinase localization in beta-cell nuclei of human and mouse pancreatic sections, as well as in human and mouse isolated islets, and murine MIN6 cells. We have identified a conserved, seven-residue nuclear localization signal (30LKKVMRR36) in the human enzyme. Substituting the residues KK31,32 and RR35,36 with AA led to a loss of its nuclear localization in transfected cells. Furthermore, our data indicates that SUMOylation of glucokinase modulates its nuclear import, while high glucose concentrations do not significantly alter the enzyme nuclear/cytosolic ratio. Thus, for the first time, we provide data in support of a nuclear import of glucokinase mediated by a redundant mechanism, involving a nuclear localization signal, and which is modulated by its SUMOylation. These findings add new knowledge to the functional role of glucokinase in the pancreatic beta-cell.
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Affiliation(s)
- Bente Berg Johansson
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Norway; Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway; Department of Pediatrics, Haukeland University Hospital, Bergen, Norway
| | - Karianne Fjeld
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Norway; Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
| | - Marie Holm Solheim
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Norway; Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway; Section on Integrative Physiology and Metabolism, Joslin Diabetes Center and Harvard Medical School, Boston, MA, USA
| | - Jun Shirakawa
- Section on Islet Cell and Regenerative Biology, Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School and Harvard Stem Cell Institute, Boston, MA, USA; Department of Endocrinology and Metabolism, Yokohama City University, Yokohama, Japan
| | | | - Magdalena Keindl
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Norway; Hormone Laboratory, Haukeland University Hospital, Bergen, Norway
| | - Jiang Hu
- Section on Islet Cell and Regenerative Biology, Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School and Harvard Stem Cell Institute, Boston, MA, USA
| | | | - Anne Døskeland
- Proteomics Unit (PROBE), Department of Biomedicine, University of Bergen, Norway
| | - Gunnar Mellgren
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Norway; Hormone Laboratory, Haukeland University Hospital, Bergen, Norway; Department of Clinical Science, University of Bergen, Bergen, Norway
| | | | - Pål Rasmus Njølstad
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Norway; Department of Pediatrics, Haukeland University Hospital, Bergen, Norway
| | - Rohit N Kulkarni
- Section on Islet Cell and Regenerative Biology, Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School and Harvard Stem Cell Institute, Boston, MA, USA
| | - Nils Wierup
- Lund University Diabetes Centre, Malmö, Sweden
| | - Ingvild Aukrust
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Norway; Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
| | - Lise Bjørkhaug
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Norway; Department of Biomedicine, University of Bergen, Bergen, Norway; Department of Biomedical Laboratory Sciences and Chemical Engineering, Western Norway University of Applied Sciences, Bergen, Norway.
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19
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Šimčíková D, Kocková L, Vackářová K, Těšínský M, Heneberg P. Evidence-based tailoring of bioinformatics approaches to optimize methods that predict the effects of nonsynonymous amino acid substitutions in glucokinase. Sci Rep 2017; 7:9499. [PMID: 28842611 PMCID: PMC5573313 DOI: 10.1038/s41598-017-09810-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 07/28/2017] [Indexed: 11/29/2022] Open
Abstract
Computational methods that allow predicting the effects of nonsynonymous substitutions are an integral part of exome studies. Here, we validated and improved their specificity by performing a comprehensive bioinformatics analysis combined with experimental and clinical data on a model of glucokinase (GCK): 8835 putative variations, including 515 disease-associated variations from 1596 families with diagnoses of monogenic diabetes (GCK-MODY) or persistent hyperinsulinemic hypoglycemia of infancy (PHHI), and 126 variations with available or newly reported (19 variations) data on enzyme kinetics. We also proved that high frequency of disease-associated variations found in patients is closely related to their evolutionary conservation. The default set prediction methods predicted correctly the effects of only a part of the GCK-MODY-associated variations and completely failed to predict the normoglycemic or PHHI-associated variations. Therefore, we calculated evidence-based thresholds that improved significantly the specificity of predictions (≤75%). The combined prediction analysis even allowed to distinguish activating from inactivating variations and identified a group of putatively highly pathogenic variations (EVmutation score <−7.5 and SNAP2 score >70), which were surprisingly underrepresented among MODY patients and thus under negative selection during molecular evolution. We suggested and validated the first robust evidence-based thresholds, which allow improved, highly specific predictions of disease-associated GCK variations.
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Affiliation(s)
- Daniela Šimčíková
- Charles University, Third Faculty of Medicine, Prague, Czech Republic
| | - Lucie Kocková
- Charles University, Third Faculty of Medicine, Prague, Czech Republic
| | | | - Miroslav Těšínský
- Charles University, Third Faculty of Medicine, Prague, Czech Republic
| | - Petr Heneberg
- Charles University, Third Faculty of Medicine, Prague, Czech Republic.
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20
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Johansson BB, Irgens HU, Molnes J, Sztromwasser P, Aukrust I, Juliusson PB, Søvik O, Levy S, Skrivarhaug T, Joner G, Molven A, Johansson S, Njølstad PR. Targeted next-generation sequencing reveals MODY in up to 6.5% of antibody-negative diabetes cases listed in the Norwegian Childhood Diabetes Registry. Diabetologia 2017; 60:625-635. [PMID: 27913849 DOI: 10.1007/s00125-016-4167-1] [Citation(s) in RCA: 87] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 11/09/2016] [Indexed: 12/18/2022]
Abstract
AIMS/HYPOTHESIS MODY can be wrongly diagnosed as type 1 diabetes in children. We aimed to find the prevalence of MODY in a nationwide population-based registry of childhood diabetes. METHODS Using next-generation sequencing, we screened the HNF1A, HNF4A, HNF1B, GCK and INS genes in all 469 children (12.1%) negative for both GAD and IA-2 autoantibodies and 469 antibody-positive matched controls selected from the Norwegian Childhood Diabetes Registry (3882 children). Variants were classified using clinical diagnostic criteria for pathogenicity ranging from class 1 (neutral) to class 5 (pathogenic). RESULTS We identified 58 rare exonic and splice variants in cases and controls. Among antibody-negative patients, 6.5% had genetic variants of classes 3-5 (vs 2.4% in controls; p = 0.002). For the stricter classification (classes 4 and 5), the corresponding number was 4.1% (vs 0.2% in controls; p = 1.6 × 10-5). HNF1A showed the strongest enrichment of class 3-5 variants, with 3.9% among antibody-negative patients (vs 0.4% in controls; p = 0.0002). Antibody-negative carriers of variants in class 3 had a similar phenotype to those carrying variants in classes 4 and 5. CONCLUSIONS/INTERPRETATION This is the first study screening for MODY in all antibody-negative children in a nationwide population-based registry. Our results suggest that the prevalence of MODY in antibody-negative childhood diabetes may reach 6.5%. One-third of these MODY cases had not been recognised by clinicians. Since a precise diagnosis is important for treatment and genetic counselling, molecular screening of all antibody-negative children should be considered in routine diagnostics.
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Affiliation(s)
- Bente B Johansson
- K. G. Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, N-5020, Bergen, Norway
- Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
| | - Henrik U Irgens
- K. G. Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, N-5020, Bergen, Norway
- Department of Paediatrics, Haukeland University Hospital, Bergen, Norway
| | - Janne Molnes
- K. G. Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, N-5020, Bergen, Norway
- Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
| | - Paweł Sztromwasser
- Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
- Computational Biology Unit, Department of Informatics, University of Bergen, Bergen, Norway
- Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Ingvild Aukrust
- K. G. Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, N-5020, Bergen, Norway
- Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
| | - Petur B Juliusson
- Department of Paediatrics, Haukeland University Hospital, Bergen, Norway
- Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Oddmund Søvik
- K. G. Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, N-5020, Bergen, Norway
- Department of Paediatrics, Haukeland University Hospital, Bergen, Norway
| | - Shawn Levy
- Hudson Alpha Institute for Biotechnology, Huntsville, AL, USA
| | - Torild Skrivarhaug
- Division of Paediatric and Adolescent Medicine, Oslo University Hospital, Oslo, Norway
| | - Geir Joner
- Division of Paediatric and Adolescent Medicine, Oslo University Hospital, Oslo, Norway
- Institute of Health and Society, University of Oslo, Oslo, Norway
| | - Anders Molven
- K. G. Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, N-5020, Bergen, Norway
- Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway
- Department of Pathology, Haukeland University Hospital, Bergen, Norway
| | - Stefan Johansson
- K. G. Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, N-5020, Bergen, Norway
- Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
| | - Pål R Njølstad
- K. G. Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, N-5020, Bergen, Norway.
- Department of Paediatrics, Haukeland University Hospital, Bergen, Norway.
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21
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Carmody D, Naylor RN, Bell CD, Berry S, Montgomery JT, Tadie EC, Hwang JL, Greeley SAW, Philipson LH. GCK-MODY in the US National Monogenic Diabetes Registry: frequently misdiagnosed and unnecessarily treated. Acta Diabetol 2016; 53:703-8. [PMID: 27106716 PMCID: PMC5016218 DOI: 10.1007/s00592-016-0859-8] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 03/19/2016] [Indexed: 12/29/2022]
Abstract
AIMS GCK-MODY leads to mildly elevated blood glucose typically not requiring therapy. It has been described in all ethnicities, but mainly in Caucasian Europeans. Here we describe our US cohort of GCK-MODY. METHODS We examined the rates of detection of heterozygous mutations in the GCK gene in individuals referred to the US Monogenic Diabetes Registry with a phenotype consistent with GCK-MODY. We also assessed referral patterns, treatment and demography, including ethnicity, of the cohort. RESULTS Deleterious heterozygous GCK mutations were found in 54.7 % of Registry probands selected for GCK sequencing for this study. Forty-nine percent were previously unnecessarily treated with glucose-lowering agents, causing hypoglycemia and other adverse effects in some of the subjects. The proportion of probands found to have a GCK mutation through research-based testing was similar across each ethnic group. However, together African-American, Latino and Asian subjects represented only 20.5 % of screened probands and 17.2 % of those with GCK-MODY, despite higher overall diabetes prevalence in these groups. CONCLUSIONS Our data show that a high detection rate of GCK-MODY is possible based on clinical phenotype and that prior to genetic diagnosis, a large percentage are inappropriately treated with glucose-lowering therapies. We also find low minority representation in our Registry, which may be due to disparities in diagnostic diabetes genetic testing and is an area needing further investigation.
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Affiliation(s)
- David Carmody
- Address correspondence to: Rochelle Naylor MD, Department of Pediatrics, The University of Chicago, 5841 S Maryland Ave, MC 5053, Chicago, Illinois 60637, , 773-702-6309
| | - Rochelle N Naylor
- Address correspondence to: Rochelle Naylor MD, Department of Pediatrics, The University of Chicago, 5841 S Maryland Ave, MC 5053, Chicago, Illinois 60637, , 773-702-6309
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22
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Kim JY, Lee DY, Lee YJ, Park KJ, Kim KH, Kim JW, Kim WH. Chronic alcohol consumption potentiates the development of diabetes through pancreatic β-cell dysfunction. World J Biol Chem 2015; 6:1-15. [PMID: 25717351 PMCID: PMC4317634 DOI: 10.4331/wjbc.v6.i1.1] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2014] [Revised: 10/29/2014] [Accepted: 12/10/2014] [Indexed: 02/05/2023] Open
Abstract
Chronic ethanol consumption is well established as a major risk factor for type-2 diabetes (T2D), which is evidenced by impaired glucose metabolism and insulin resistance. However, the relationships between alcohol consumption and the development of T2D remain controversial. In particular, the direct effects of ethanol consumption on proliferation of pancreatic β-cell and the exact mechanisms associated with ethanol-mediated β-cell dysfunction and apoptosis remain elusive. Although alcoholism and alcohol consumption are prevalent and represent crucial public health problems worldwide, many people believe that low-to-moderate ethanol consumption may protect against T2D and cardiovascular diseases. However, the J- or U-shaped curves obtained from cross-sectional and large prospective studies have not fully explained the relationship between alcohol consumption and T2D. This review provides evidence for the harmful effects of chronic ethanol consumption on the progressive development of T2D, particularly with respect to pancreatic β-cell mass and function in association with insulin synthesis and secretion. This review also discusses a conceptual framework for how ethanol-produced peroxynitrite contributes to pancreatic β-cell dysfunction and metabolic syndrome.
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23
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Raimondo A, Chakera AJ, Thomsen SK, Colclough K, Barrett A, De Franco E, Chatelas A, Demirbilek H, Akcay T, Alawneh H, Flanagan SE, Van De Bunt M, Hattersley AT, Gloyn AL, Ellard S. Phenotypic severity of homozygous GCK mutations causing neonatal or childhood-onset diabetes is primarily mediated through effects on protein stability. Hum Mol Genet 2014; 23:6432-40. [PMID: 25015100 PMCID: PMC4240195 DOI: 10.1093/hmg/ddu360] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Mutations in glucokinase (GCK) cause a spectrum of glycemic disorders. Heterozygous loss-of-function mutations cause mild fasting hyperglycemia irrespective of mutation severity due to compensation from the unaffected allele. Conversely, homozygous loss-of-function mutations cause permanent neonatal diabetes requiring lifelong insulin treatment. This study aimed to determine the relationship between in vitro mutation severity and clinical phenotype in a large international case series of patients with homozygous GCK mutations. Clinical characteristics for 30 patients with diabetes due to homozygous GCK mutations (19 unique mutations, including 16 missense) were compiled and assigned a clinical severity grade (CSG) based on birth weight and age at diagnosis. The majority (28 of 30) of subjects were diagnosed before 9 months, with the remaining two at 9 and 15 years. These are the first two cases of a homozygous GCK mutation diagnosed outside infancy. Recombinant mutant GCK proteins were analyzed for kinetic and thermostability characteristics and assigned a relative activity index (RAI) or relative stability index (RSI) value. Six of 16 missense mutations exhibited severe kinetic defects (RAI ≤ 0.01). There was no correlation between CSG and RAI (r(2) = 0.05, P = 0.39), indicating that kinetics alone did not explain the phenotype. Eighty percent of the remaining mutations showed reduced thermostability, the exceptions being the two later-onset mutations which exhibited increased thermostability. Comparison of CSG with RSI detected a highly significant correlation (r(2) = 0.74, P = 0.002). We report the largest case series of homozygous GCK mutations to date and demonstrate that they can cause childhood-onset diabetes, with protein instability being the major determinant of mutation severity.
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Affiliation(s)
- Anne Raimondo
- Oxford Centre for Diabetes Endocrinology & Metabolism, University of Oxford, Oxford OX3 7LE, UK
| | - Ali J Chakera
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter EX2 5DW, UK, Macleod Diabetes and Endocrine Centre and
| | - Soren K Thomsen
- Oxford Centre for Diabetes Endocrinology & Metabolism, University of Oxford, Oxford OX3 7LE, UK
| | - Kevin Colclough
- Molecular Genetics Laboratory, Royal Devon and Exeter NHS Foundation Trust, Exeter EX2 5DW, UK
| | - Amy Barrett
- Oxford Centre for Diabetes Endocrinology & Metabolism, University of Oxford, Oxford OX3 7LE, UK
| | - Elisa De Franco
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter EX2 5DW, UK
| | - Alisson Chatelas
- Oxford Centre for Diabetes Endocrinology & Metabolism, University of Oxford, Oxford OX3 7LE, UK
| | - Huseyin Demirbilek
- Department of Paediatric Endocrinology, Diyarbakir Children State Hospital, Diyarbakir 21100, Turkey
| | - Teoman Akcay
- Division of Pediatric Endocrinology, Dr Sadi Konuk Education and Research Hospital, Bakirkoy, Istanbul 34147, Turkey
| | - Hussein Alawneh
- Pediatric Endocrine Division, Queen Rania Al Abdullah Hospital for Children, King Hussein Medical Center, Royal Medical Services, Amman 11814, Jordan and
| | | | - Sarah E Flanagan
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter EX2 5DW, UK
| | - Martijn Van De Bunt
- Oxford Centre for Diabetes Endocrinology & Metabolism, University of Oxford, Oxford OX3 7LE, UK
| | - Andrew T Hattersley
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter EX2 5DW, UK, Macleod Diabetes and Endocrine Centre and
| | - Anna L Gloyn
- Oxford Centre for Diabetes Endocrinology & Metabolism, University of Oxford, Oxford OX3 7LE, UK, Oxford NIHR Biomedical Research Centre, Churchill Hospital, Oxford OX3 7LE, UK
| | - Sian Ellard
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter EX2 5DW, UK, Molecular Genetics Laboratory, Royal Devon and Exeter NHS Foundation Trust, Exeter EX2 5DW, UK
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24
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Chen K, Michelsen K, Kurzeja RJM, Han J, Vazir M, St Jean DJ, Hale C, Wahl RC. Discovery of Small-Molecule Glucokinase Regulatory Protein Modulators That Restore Glucokinase Activity. ACTA ACUST UNITED AC 2014; 19:1014-23. [PMID: 24717911 DOI: 10.1177/1087057114530468] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Accepted: 03/01/2014] [Indexed: 11/16/2022]
Abstract
In the nuclei of hepatocytes, glucokinase regulatory protein (GKRP) modulates the activity of glucokinase (GK), a key regulator of glucose homeostasis. Currently, direct activators of GK (GKAs) are in development for the treatment of type 2 diabetes. However, this approach is generally associated with a risk of hypoglycemia. To mitigate such risk, we target the GKRP regulation, which indirectly restores GK activity. Here we describe a screening strategy to look specifically for GKRP modulators, in addition to traditional GKAs. Two high-throughput screening campaigns were performed with our compound libraries using a luminescence assay format, one with GK alone and the other with a GK/GKRP complex in the presence of sorbitol-6-phosphate (S6P). By a subtraction method in the hit triage process of these campaigns, we discovered two close analogs that bind GKRP specifically with sub-µM potency to a site distinct from where fructose-1-phosphate binds. These small molecules are first-in-class allosteric modulators of the GK/GKRP interaction and are fully active even in the presence of S6P. Activation of GK by this particular mechanism, without altering the enzymatic profile, represents a novel pharmacologic modality of intervention in the GK/GKRP pathway.
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Affiliation(s)
- Kui Chen
- Amgen, Inc, Molecular Structure and Characterization, Thousand Oaks, CA, USA
| | - Klaus Michelsen
- Amgen, Inc, Molecular Structure and Characterization, Cambridge, MA, USA
| | | | - Joon Han
- Amgen, Inc, Biologic Discovery, Thousand Oaks, CA, USA
| | - Mukta Vazir
- Amgen, Inc, Protein Technologies, Thousand Oaks, CA, USA
| | | | - Clarence Hale
- Amgen, Inc, Metabolic Disorders, Thousand Oaks, CA, USA
| | - Robert C Wahl
- Amgen, Inc, Molecular Structure and Characterization, Thousand Oaks, CA, USA
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25
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Negahdar M, Aukrust I, Molnes J, Solheim MH, Johansson BB, Sagen JV, Dahl-Jørgensen K, Kulkarni RN, Søvik O, Flatmark T, Njølstad PR, Bjørkhaug L. GCK-MODY diabetes as a protein misfolding disease: the mutation R275C promotes protein misfolding, self-association and cellular degradation. Mol Cell Endocrinol 2014; 382:55-65. [PMID: 24001579 DOI: 10.1016/j.mce.2013.08.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Revised: 08/22/2013] [Accepted: 08/23/2013] [Indexed: 11/28/2022]
Abstract
GCK-MODY, dominantly inherited mild hyperglycemia, is associated with more than 600 mutations in the glucokinase gene. Different molecular mechanisms have been shown to explain GCK-MODY. Here, we report a Pakistani family harboring the glucokinase mutation c.823C>T (p.R275C). The recombinant and in cellulo expressed mutant pancreatic enzyme revealed slightly increased enzyme activity (kcat) and normal affinity for α-D-glucose, and resistance to limited proteolysis by trypsin comparable with wild-type. When stably expressed in HEK293 cells and MIN6 β-cells (at different levels), the mutant protein appeared misfolded and unstable with a propensity to form dimers and aggregates. Its degradation rate was increased, involving the lysosomal and proteasomal quality control systems. On mutation, a hydrogen bond between the R275 side-chain and the carbonyl oxygen of D267 is broken, destabilizing the F260-L271 loop structure and the protein. This promotes the formation of dimers/aggregates and suggests that an increased cellular degradation is the molecular mechanism by which R275C causes GCK-MODY.
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Affiliation(s)
- Maria Negahdar
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway; Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
| | - Ingvild Aukrust
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway; Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway; Department of Biomedicine, University of Bergen, Bergen, Norway; Section of Islet Cell Biology and Regenerative Medicine, Joslin Diabetes Center, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Janne Molnes
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway; Department of Biomedicine, University of Bergen, Bergen, Norway; Department of Pediatrics, Haukeland University Hospital, Bergen, Norway
| | - Marie H Solheim
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway; Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway; Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Bente B Johansson
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway; Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway; Department of Pediatrics, Haukeland University Hospital, Bergen, Norway
| | - Jørn V Sagen
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway; Institute of Medicine, University of Bergen, Bergen, Norway; Hormone Laboratory, Haukeland University Hospital, Bergen, Norway
| | - Knut Dahl-Jørgensen
- Pediatric Department Ullevaal, Oslo University Hospital, Oslo, Norway; Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Rohit N Kulkarni
- Section of Islet Cell Biology and Regenerative Medicine, Joslin Diabetes Center, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Oddmund Søvik
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway
| | | | - Pål R Njølstad
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway; Department of Pediatrics, Haukeland University Hospital, Bergen, Norway.
| | - Lise Bjørkhaug
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway; Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway; Department of Biomedicine, University of Bergen, Bergen, Norway
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26
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The ubiquitin-proteasome system regulates the stability and activity of the glucose sensor glucokinase in pancreatic β-cells. Biochem J 2014; 456:173-84. [PMID: 24028089 DOI: 10.1042/bj20130262] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The ubiquitin-proteasome system is important to maintain pancreatic β-cell function. Inhibition of the proteasome significantly reduced glucose-induced insulin secretion. Key regulators of the stimulus/secretion cascade seem to be affected by protein misfolding if the proteasome is down-regulated as recently reported in humans with Type 2 diabetes. It remains unknown, however, whether the glucose sensor enzyme glucokinase is involved in this process. A direct interaction between glucokinase and ubiquitin could be shown in vivo by FRET, suggesting regulation of glucokinase by the proteasome. After proteasome inhibition glucokinase activity was significantly reduced in MIN6 cells, whereas the protein content was increased, indicating protein misfolding. Enhancing the availability of chaperones by cyclohexamide could induce refolding and restored glucokinase activity. Glucokinase aggregation due to proteasome blocking with MG132, bortezomib, epoxomicin or lactacystin could be detected in MIN6 cells, primary β-cells and hepatocytes using fluorescence-based assays. Glucokinase aggresome formation proceeded microtubule-assisted and was avoided by cyclohexamide. Thus the results of the present study provide support for glucokinase misfolding and aggregation in case of a diminished capacity of the ubiquitin-proteasome system in pancreatic β-cells. In the Type 2 diabetic situation this could contribute to reduced glucose-induced insulin secretion.
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27
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Flannick J, Beer NL, Bick AG, Agarwala V, Molnes J, Gupta N, Burtt NP, Florez JC, Meigs JB, Taylor H, Lyssenko V, Irgens H, Fox E, Burslem F, Johansson S, Brosnan MJ, Trimmer JK, Newton-Cheh C, Tuomi T, Molven A, Wilson JG, O'Donnell CJ, Kathiresan S, Hirschhorn JN, Njølstad PR, Rolph T, Seidman J, Gabriel S, Cox DR, Seidman C, Groop L, Altshuler D. Assessing the phenotypic effects in the general population of rare variants in genes for a dominant Mendelian form of diabetes. Nat Genet 2013; 45:1380-5. [PMID: 24097065 PMCID: PMC4051627 DOI: 10.1038/ng.2794] [Citation(s) in RCA: 105] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Accepted: 09/13/2013] [Indexed: 12/25/2022]
Abstract
Genome sequencing can identify individuals in the general population who harbor rare coding variants in genes for Mendelian disorders and who may consequently have increased disease risk. Previous studies of rare variants in phenotypically extreme individuals display ascertainment bias and may demonstrate inflated effect-size estimates. We sequenced seven genes for maturity-onset diabetes of the young (MODY) in well-phenotyped population samples (n = 4,003). We filtered rare variants according to two prediction criteria for disease-causing mutations: reported previously in MODY or satisfying stringent de novo thresholds (rare, conserved and protein damaging). Approximately 1.5% and 0.5% of randomly selected individuals from the Framingham and Jackson Heart Studies, respectively, carry variants from these two classes. However, the vast majority of carriers remain euglycemic through middle age. Accurate estimates of variant effect sizes from population-based sequencing are needed to avoid falsely predicting a substantial fraction of individuals as being at risk for MODY or other Mendelian diseases.
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Affiliation(s)
- Jason Flannick
- Program in Medical and Population Genetics, Broad Institute of Harvard and MIT, Cambridge, MA, USA
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA
- Diabetes Unit, Massachusetts General Hospital, Boston, MA, USA
| | - Nicola L Beer
- Program in Medical and Population Genetics, Broad Institute of Harvard and MIT, Cambridge, MA, USA
| | - Alexander G Bick
- Program in Medical and Population Genetics, Broad Institute of Harvard and MIT, Cambridge, MA, USA
- Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Vineeta Agarwala
- Program in Medical and Population Genetics, Broad Institute of Harvard and MIT, Cambridge, MA, USA
- Harvard-MIT Division of Health Sciences and Technology, MIT, Cambridge, MA, USA
- Program in Biophysics, Graduate School of Arts and Sciences, Harvard University, Cambridge, MA, USA
| | - Janne Molnes
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Namrata Gupta
- Program in Medical and Population Genetics, Broad Institute of Harvard and MIT, Cambridge, MA, USA
| | - Noel P Burtt
- Program in Medical and Population Genetics, Broad Institute of Harvard and MIT, Cambridge, MA, USA
| | - Jose C Florez
- Program in Medical and Population Genetics, Broad Institute of Harvard and MIT, Cambridge, MA, USA
- Center for Human Genetic Research, Massachusetts General Hospital, Boston, MA, USA
- Department of Medicine, Harvard Medical School, Boston, MA, USA
| | - James B Meigs
- Department of Medicine, Harvard Medical School, Boston, MA, USA
- General Medicine Division, Massachusetts General Hospital, Boston, MA, USA
| | - Herman Taylor
- Department of Medicine, University of Mississippi Medical Center, Jackson, MS, USA
- Jackson State University, Jackson, MS, USA
- Tougaloo College, Tougaloo MS, USA
| | - Valeriya Lyssenko
- Department of Clinical Sciences, Diabetes and Endocrinology, Clinical Research Centre, Lund University, Malmö, Sweden
| | - Henrik Irgens
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway
- Department of Pediatrics, Haukeland University Hospital, Bergen, Norway
| | - Ervin Fox
- Department of Medicine, University of Mississippi Medical Center, Jackson, MS, USA
| | - Frank Burslem
- Cardiovascular and Metabolic Diseases Practice, Prescient Life Sciences, London, UK
| | - Stefan Johansson
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway
- Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
| | - M Julia Brosnan
- Cardiovascular and Metabolic Diseases Research Unit, Pfizer Inc., Cambridge, MA, USA
| | - Jeff K Trimmer
- Cardiovascular and Metabolic Diseases Research Unit, Pfizer Inc., Cambridge, MA, USA
| | - Christopher Newton-Cheh
- Program in Medical and Population Genetics, Broad Institute of Harvard and MIT, Cambridge, MA, USA
- Center for Human Genetic Research, Massachusetts General Hospital, Boston, MA, USA
- National Heart, Lung, and Blood Institute's Framingham Heart Study, Framingham, MA, USA
- Cardiology Division, Massachusetts General Hospital, Boston, MA, USA
| | - Tiinamaija Tuomi
- Department of General Practice and Primary Health Care, University of Helsinki, Helsinki, Finland
- Department of Medicine, Helsinki University Central Hospital and Research Program for Molecular Medicine
| | - Anders Molven
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway
- Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway
- Department of Pathology, Haukeland University Hospital, Bergen, Norway
| | - James G Wilson
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS, USA
| | - Christopher J O'Donnell
- National Heart, Lung, and Blood Institute's Framingham Heart Study, Framingham, MA, USA
- Cardiology Division, Massachusetts General Hospital, Boston, MA, USA
- Division of Intramural Research, National Heart, Lung, and Blood Institute, Bethesda, MD, USA
| | - Sekar Kathiresan
- Program in Medical and Population Genetics, Broad Institute of Harvard and MIT, Cambridge, MA, USA
- Center for Human Genetic Research, Massachusetts General Hospital, Boston, MA, USA
- Cardiology Division, Massachusetts General Hospital, Boston, MA, USA
| | - Joel N Hirschhorn
- Program in Medical and Population Genetics, Broad Institute of Harvard and MIT, Cambridge, MA, USA
- Department of Genetics, Harvard Medical School, Boston, MA, USA
- Divisions of Genetics and Endocrinology and Program in Genomics, Children's Hospital, Boston, MA, USA
| | - Pål R Njølstad
- Program in Medical and Population Genetics, Broad Institute of Harvard and MIT, Cambridge, MA, USA
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway
- Department of Pediatrics, Haukeland University Hospital, Bergen, Norway
| | - Tim Rolph
- Cardiovascular and Metabolic Diseases Research Unit, Pfizer Inc., Cambridge, MA, USA
| | - J.G. Seidman
- Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Stacey Gabriel
- Program in Medical and Population Genetics, Broad Institute of Harvard and MIT, Cambridge, MA, USA
| | - David R Cox
- Applied Quantitative Genotherapeutics, Pfizer Inc., South San Francisco, CA, USA
| | - Christine Seidman
- Department of Genetics, Harvard Medical School, Boston, MA, USA
- Division of Cardiovascular Medicine, Brigham and Women’s Hospital, Boston, MA, USA
- Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Leif Groop
- Department of Clinical Sciences, Diabetes and Endocrinology, Clinical Research Centre, Lund University, Malmö, Sweden
- Finnish Institute for Molecular Medicine (FIMM), Helsinki University, Helsinki, Finland
| | - David Altshuler
- Program in Medical and Population Genetics, Broad Institute of Harvard and MIT, Cambridge, MA, USA
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA
- Department of Genetics, Harvard Medical School, Boston, MA, USA
- Department of Medicine, Harvard Medical School, Boston, MA, USA
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28
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Oh YS, Lee YJ, Park K, Choi HH, Yoo S, Jun HS. Treatment with glucokinase activator, YH-GKA, increases cell proliferation and decreases glucotoxic apoptosis in INS-1 cells. Eur J Pharm Sci 2013; 51:137-45. [PMID: 24056026 DOI: 10.1016/j.ejps.2013.09.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Revised: 08/31/2013] [Accepted: 09/09/2013] [Indexed: 12/17/2022]
Abstract
Glucokinase (GK), an enzyme that phosphorylates glucose to form glucose-6-phosphate, has a role in regulating insulin secretion and proliferation in beta cells. GK activators (GKAs) have been developed as new therapies for type 2 diabetes. In this study, we evaluated the proliferation and anti-apoptotic actions of YH-GKA, a novel and potent GKA, in INS-1 pancreatic β-cells. YH-GKA treatment increased cell numbers at 3 mM glucose via upregulation of insulin receptor substrate-2 and subsequent activation of AKT/protein kinase B phosphorylation. YH-GKA also increased beta-catenin and cyclin D2 mRNA expression and inactivated GSK3β by increasing phosphorylation. These proliferative effects of YH-GKA were attenuated by IRS-2 downregulation. Moreover, YH-GKA reduced annexin-V-stained cells and expression levels of cleaved poly (ADP-ribose) polymerase and caspase-3 induced by glucotoxicity. YH-GKA inhibited apoptotic signaling via induction of ATP content, mitochondrial membrane potential, and citrate synthase activity and was correlated with changes of the mitochondrial function-related genes. YH-GKA also increased interaction between GK and voltage-dependent anion-selective channel protein. Our results suggest that the novel GKA, YH-GKA, promotes beta cell growth and prevents glucotoxic beta cell apoptosis. Therefore, YH-GKA may provide a therapy that compensates for beta cell loss in patients with type 2 diabetes.
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Affiliation(s)
- Yoon Sin Oh
- Lee Gil Ya Cancer and Diabetes Institute, Gachon University, 7-45 Songdo-dong, Yeonsu-ku, Incheon, Republic of Korea; Gachon Medical Research Institute, Gil Hospital, 1198, Guwol-dong, Namdong-Gu, Incheon, Republic of Korea
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29
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Aukrust I, Bjørkhaug L, Negahdar M, Molnes J, Johansson BB, Müller Y, Haas W, Gygi SP, Søvik O, Flatmark T, Kulkarni RN, Njølstad PR. SUMOylation of pancreatic glucokinase regulates its cellular stability and activity. J Biol Chem 2013; 288:5951-62. [PMID: 23297408 DOI: 10.1074/jbc.m112.393769] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Glucokinase is the predominant hexokinase expressed in hepatocytes and pancreatic β-cells, with a pivotal role in regulating glucose-stimulated insulin secretion, illustrated by glucokinase gene mutations causing monogenic diabetes and congenital hyperinsulinemic hypoglycemia. A complex tissue-specific network of mechanisms regulates this enzyme, and a major unanswered question in glucokinase biology is how post-translational modifications control the function of the enzyme. Here, we show that the pancreatic isoform of human glucokinase is SUMOylated in vitro, using recombinant enzymes, and in insulin-secreting model cells. Three N-terminal lysines unique for the pancreatic isoform (Lys-12/Lys-13 and/or Lys-15) may represent one SUMOylation site, with an additional site (Lys-346) common for the pancreatic and the liver isoform. SUMO-1 and E2 overexpression stabilized preferentially the wild-type human pancreatic enzyme in MIN6 β-cells, and SUMOylation increased the catalytic activity of recombinant human glucokinase in vitro and also of glucokinase in target cells. Small ubiquitin-like modifier conjugation represents a novel form of post-translational modification of the enzyme, and it may have an important regulatory function in pancreatic β-cells.
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Affiliation(s)
- Ingvild Aukrust
- KG Jebsen Center for Diabetes Research, Department of Clinical Medicine, N-5020 Bergen, Norway
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30
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Negahdar M, Aukrust I, Johansson BB, Molnes J, Molven A, Matschinsky FM, Søvik O, Kulkarni RN, Flatmark T, Njølstad PR, Bjørkhaug L. GCK-MODY diabetes associated with protein misfolding, cellular self-association and degradation. Biochim Biophys Acta Mol Basis Dis 2012; 1822:1705-15. [PMID: 22820548 DOI: 10.1016/j.bbadis.2012.07.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2012] [Revised: 06/17/2012] [Accepted: 07/12/2012] [Indexed: 12/31/2022]
Abstract
GCK-MODY, dominantly inherited mild fasting hyperglycemia, has been associated with >600 different mutations in the glucokinase (GK)-encoding gene (GCK). When expressed as recombinant pancreatic proteins, some mutations result in enzymes with normal/near-normal catalytic properties. The molecular mechanism(s) of GCK-MODY due to these mutations has remained elusive. Here, we aimed to explore the molecular mechanisms for two such catalytically 'normal' GCK mutations (S263P and G264S) in the F260-L270 loop of GK. When stably overexpressed in HEK293 cells and MIN6 β-cells, the S263P- and G264S-encoded mutations generated misfolded proteins with an increased rate of degradation (S263P>G264S) by the protein quality control machinery, and a propensity to self-associate (G264S>S263P) and form dimers (SDS resistant) and aggregates (partly Triton X-100 insoluble), as determined by pulse-chase experiments and subcellular fractionation. Thus, the GCK-MODY mutations S263P and G264S lead to protein misfolding causing destabilization, cellular dimerization/aggregation and enhanced rate of degradation. In silico predicted conformational changes of the F260-L270 loop structure are considered to mediate the dimerization of both mutant proteins by a domain swapping mechanism. Thus, similar properties may represent the molecular mechanisms for additional unexplained GCK-MODY mutations, and may also contribute to the disease mechanism in other previously characterized GCK-MODY inactivating mutations.
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Affiliation(s)
- Maria Negahdar
- Department of Clinical Medicine, University of Bergen, N-5020 Bergen, Norway
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31
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Identification and functional characterisation of novel glucokinase mutations causing maturity-onset diabetes of the young in Slovakia. PLoS One 2012; 7:e34541. [PMID: 22493702 PMCID: PMC3321013 DOI: 10.1371/journal.pone.0034541] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Accepted: 03/01/2012] [Indexed: 11/19/2022] Open
Abstract
Heterozygous glucokinase (GCK) mutations cause a subtype of maturity-onset diabetes of the young (GCK-MODY). Over 600 GCK mutations have been reported of which ∼65% are missense. In many cases co-segregation has not been established and despite the importance of functional studies in ascribing pathogenicity for missense variants these have only been performed for <10% of mutations. The aim of this study was to determine the minimum prevalence of GCK-MODY amongst diabetic subjects in Slovakia by sequencing GCK in 100 Slovakian probands with a phenotype consistent with GCK-MODY and to explore the pathogenicity of identified variants through family and functional studies. Twenty-two mutations were identified in 36 families (17 missense) of which 7 (I110N, V200A, N204D, G258R, F419S, c.580-2A>C, c.1113-1114delGC) were novel. Parental DNA was available for 22 probands (covering 14/22 mutations) and co-segregation established in all cases. Bioinformatic analysis predicted all missense mutations to be damaging. Nine (I110N, V200A, N204D, G223S, G258R, F419S, V244G, L315H, I436N) mutations were functionally evaluated. Basic kinetic analysis explained pathogenicity for 7 mutants which showed reduced glucokinase activity with relative activity indices (RAI) between 0.6 to <0.001 compared to wild-type GCK (1.0). For the remaining 2 mutants additional molecular mechanisms were investigated. Differences in glucokinase regulatory protein (GKRP) -mediated-inhibition of GCK were observed for both L315H & I436N when compared to wild type (IC(50) 14.6±0.1 mM & 20.3±1.6 mM vs.13.3±0.1 mM respectively [p<0.03]). Protein instability as assessed by thermal lability studies demonstrated that both L315H and I436N show marked thermal instability compared to wild-type GCK (RAI at 55°C 8.8±0.8% & 3.1±0.4% vs. 42.5±3.9% respectively [p<0.001]). The minimum prevalence of GCK-MODY amongst Slovakian patients with diabetes was 0.03%. In conclusion, we have identified 22 GCK mutations in 36 Slovakian probands and demonstrate that combining family, bioinformatic and functional studies can aid the interpretation of variants identified by molecular diagnostic screening.
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32
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Zelent B, Buettger C, Grimsby J, Sarabu R, Vanderkooi JM, Wand AJ, Matschinsky FM. Thermal stability of glucokinase (GK) as influenced by the substrate glucose, an allosteric glucokinase activator drug (GKA) and the osmolytes glycerol and urea. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2012; 1824:769-84. [PMID: 22446163 DOI: 10.1016/j.bbapap.2012.03.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Revised: 02/15/2012] [Accepted: 03/05/2012] [Indexed: 11/27/2022]
Abstract
We investigated how glycerol, urea, glucose and a GKA influence kinetics and stability of wild-type and mutant GK. Glycerol and glucose stabilized GK additively. Glycerol barely affected the TF spectra of all GKs but decreased k(cat), glucose S(0.5) and K(D) values and ATP K(M) while leaving cooperativity unchanged. Glycerol sensitized all GKs to GKA as shown by TF. Glucose increased TF of GKs without influence of glycerol on the effect. Glycerol and GKA affected kinetics and binding additively. The activation energies for thermal denaturation of GK were a function of glucose with K(D)s of 3 and 1mM without and with glycerol, respectively. High urea denatured wild type GK reversibly at 20 and 60°C and urea treatment of irreversibly heat denatured GK allowed refolding as demonstrated by TF including glucose response. We concluded: Glycerol stabilizes GK indirectly without changing the folding structure of the apoenzyme, by restructuring the surface water of the protein, whereas glucose stabilizes GK directly by binding to its substrate site and inducing a compact conformation. Glucose or glycerol (alone or combined) is unable to prevent irreversible heat denaturation above 40°C. However, urea denatures GK reversibly even at 60°C by binding to the protein backbone and directly interacting with hydrophobic side chains. It prevents irreversible aggregation allowing complete refolding when urea is removed. This study establishes the foundation for exploring numerous instability mutants among the more than 600 variant GKs causing diabetes in animals and humans.
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Affiliation(s)
- B Zelent
- Department of Biochemistry and Biophysics and Diabetes Research Center, University of Pennsylvania, Philadelphia, PA 19104, USA
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Larion M, Miller BG. Homotropic allosteric regulation in monomeric mammalian glucokinase. Arch Biochem Biophys 2012; 519:103-11. [PMID: 22107947 PMCID: PMC3294010 DOI: 10.1016/j.abb.2011.11.007] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Revised: 11/03/2011] [Accepted: 11/04/2011] [Indexed: 11/30/2022]
Abstract
Glucokinase catalyzes the ATP-dependent phosphorylation of glucose, a chemical transformation that represents the rate-limiting step of glycolytic metabolism in the liver and pancreas. Glucokinase is a central regulator of glucose homeostasis as evidenced by its association with two disease states, maturity onset diabetes of the young (MODY) and persistent hyperinsulinemia of infancy (PHHI). Mammalian glucokinase is subject to homotropic allosteric regulation by glucose-the steady-state velocity of glucose-6-phosphate production is not hyperbolic, but instead displays a sigmoidal response to increasing glucose concentrations. The positive cooperativity displayed by glucokinase is intriguing since the enzyme functions as a monomer under physiological conditions and contains only a single binding site for glucose. Despite the existence of several models of kinetic cooperativity in monomeric enzymes, a consensus has yet to be reached regarding the mechanism of allosteric regulation in glucokinase. Experimental evidence collected over the last 45 years by a number of investigators supports a link between cooperativity and slow conformational reorganizations of the glucokinase scaffold. In this review, we summarize advances in our understanding of glucokinase allosteric regulation resulting from recent X-ray crystallographic, pre-equilibrium kinetic and high-resolution nuclear magnetic resonance investigations. We conclude with a brief discussion of unanswered questions regarding the mechanistic basis of kinetic cooperativity in mammalian glucokinase.
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Affiliation(s)
- Mioara Larion
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306-4390, USA
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García-Herrero CM, Rubio-Cabezas O, Azriel S, Gutierrez-Nogués A, Aragonés A, Vincent O, Campos-Barros A, Argente J, Navas MA. Functional characterization of MODY2 mutations highlights the importance of the fine-tuning of glucokinase and its role in glucose sensing. PLoS One 2012; 7:e30518. [PMID: 22291974 PMCID: PMC3265476 DOI: 10.1371/journal.pone.0030518] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Accepted: 12/17/2011] [Indexed: 11/19/2022] Open
Abstract
Glucokinase (GK) acts as a glucose sensor in the pancreatic beta-cell and regulates insulin secretion. Heterozygous mutations in the human GK-encoding GCK gene that reduce the activity index increase the glucose-stimulated insulin secretion threshold and cause familial, mild fasting hyperglycaemia, also known as Maturity Onset Diabetes of the Young type 2 (MODY2). Here we describe the biochemical characterization of five missense GK mutations: p.Ile130Thr, p.Asp205His, p.Gly223Ser, p.His416Arg and p.Ala449Thr. The enzymatic analysis of the corresponding bacterially expressed GST-GK mutant proteins show that all of them impair the kinetic characteristics of the enzyme. In keeping with their position within the protein, mutations p.Ile130Thr, p.Asp205His, p.Gly223Ser, and p.His416Arg strongly decrease the activity index of GK, affecting to one or more kinetic parameters. In contrast, the p.Ala449Thr mutation, which is located in the allosteric activator site, does not affect significantly the activity index of GK, but dramatically modifies the main kinetic parameters responsible for the function of this enzyme as a glucose sensor. The reduced Kcat of the mutant (3.21±0.28 s(-1) vs 47.86±2.78 s(-1)) is balanced by an increased glucose affinity (S(0.5) = 1.33±0.08 mM vs 7.86±0.09 mM) and loss of cooperativity for this substrate. We further studied the mechanism by which this mutation impaired GK kinetics by measuring the differential effects of several competitive inhibitors and one allosteric activator on the mutant protein. Our results suggest that this mutation alters the equilibrium between the conformational states of glucokinase and highlights the importance of the fine-tuning of GK and its role in glucose sensing.
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Affiliation(s)
- Carmen-María García-Herrero
- Departamento de Bioquímica y Biología Molecular III, Facultad de Medicina, Universidad Complutense de Madrid and Instituto de Investigación Sanitaria del Hospital Clínico San Carlos, Madrid, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas (CIBERDEM), www.ciberdem.net, Instituto de Salud Carlos III, Madrid, Spain
| | - Oscar Rubio-Cabezas
- Servicio de Endocrinología, Hospital Infantil Universitario Niño Jesús, Instituto de Investigación La Princesa and Departamento de Pediatría, Universidad Autónoma de Madrid, Madrid, Spain
- Centro de Investigación Biomédica en Red de la Fisiopatología de la Obesidad y Nutrición (CIBEROBN), www.ciberobn.es, Instituto de Salud Carlos III, Madrid, Spain
| | - Sharona Azriel
- Servicio de Endocrinología, Hospital Universitario Infanta Sofía, San Sebastián de los Reyes, Madrid, Spain
| | - Angel Gutierrez-Nogués
- Departamento de Bioquímica y Biología Molecular III, Facultad de Medicina, Universidad Complutense de Madrid and Instituto de Investigación Sanitaria del Hospital Clínico San Carlos, Madrid, Spain
| | - Angel Aragonés
- Servicio de Pediatría, Hospital Virgen de la Salud, Toledo, Spain
| | - Olivier Vincent
- Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, Madrid, Spain
| | - Angel Campos-Barros
- Servicio de Endocrinología, Hospital Infantil Universitario Niño Jesús, Instituto de Investigación La Princesa and Departamento de Pediatría, Universidad Autónoma de Madrid, Madrid, Spain
| | - Jesús Argente
- Servicio de Endocrinología, Hospital Infantil Universitario Niño Jesús, Instituto de Investigación La Princesa and Departamento de Pediatría, Universidad Autónoma de Madrid, Madrid, Spain
- Centro de Investigación Biomédica en Red de la Fisiopatología de la Obesidad y Nutrición (CIBEROBN), www.ciberobn.es, Instituto de Salud Carlos III, Madrid, Spain
| | - María-Angeles Navas
- Departamento de Bioquímica y Biología Molecular III, Facultad de Medicina, Universidad Complutense de Madrid and Instituto de Investigación Sanitaria del Hospital Clínico San Carlos, Madrid, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas (CIBERDEM), www.ciberdem.net, Instituto de Salud Carlos III, Madrid, Spain
- * E-mail:
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Abstract
GK (glucokinase) is activated by glucose binding to its substrate site, is inhibited by GKRP (GK regulatory protein) and stimulated by GKAs (GK activator drugs). To explore further the mechanisms of these processes we studied pure recombinant human GK (normal enzyme and a selection of 31 mutants) using steady-state kinetics of the enzyme and TF (tryptophan fluorescence). TF studies of the normal binary GK-glucose complex corroborate recent crystallography studies showing that it exists in a closed conformation greatly different from the open conformation of the ligand-free structure, but indistinguishable from the ternary GK-glucose-GKA complex. GKAs did activate and GKRP did inhibit normal GK, whereas its TF was doubled by glucose saturation. However, the enzyme kinetics, GKRP inhibition, TF enhancement by glucose and responsiveness to GKA of the selected mutants varied greatly. Two predominant response patterns were identified accounting for nearly all mutants: (i) GK mutants with a normal or close to normal response to GKA, normally low basal TF (indicating an open conformation), some variability of kinetic parameters (k(cat), glucose S(0.5), h and ATP K(m)), but usually strong GKRP inhibition (13/31); and (ii) GK mutants that are refractory to GKAs, exhibit relatively high basal TF (indicating structural compaction and partial closure), usually show strongly enhanced catalytic activity primarily due to lowering of the glucose S(0.5), but with reduced or no GKRP inhibition in most cases (14/31). These results and those of previous studies are best explained by envisioning a common allosteric regulator region with spatially non-overlapping GKRP- and GKA-binding sites.
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36
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Genes related to diabetes may be associated with pancreatic cancer in a population-based case-control study in Minnesota. Pancreas 2012; 41:50-3. [PMID: 22015968 PMCID: PMC3241825 DOI: 10.1097/mpa.0b013e3182247625] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
OBJECTIVES Type 2 diabetes is associated with increased pancreatic cancer risk; however, the nature of this relationship is not clear. We examined the link between 10 diabetes-related single-nucleotide polymorphisms and pancreatic cancer in a case-control study conducted in 1994 to 1998. METHODS Cases (n = 162) were ascertained from hospitals in the Twin Cities and Mayo Clinic, Minn. Controls (n = 540) from the general population were frequency matched by age, sex, and race. Unconditional logistic regression provided odds ratios of pancreatic cancer and 95% confidence intervals (95% CIs). RESULTS In a multivariate-adjusted model, a significant association was observed only for rs780094 in the glucokinase regulator (GCKR) gene: odds ratios for pancreatic cancer were 1.00 for TT, 1.35 (95% CI, 0.71-2.58) for CT, and 2.14 (95% CI, 1.12-4.08) for CC genotypes (P trend = 0.01) and did not change after the adjustment for diabetes. CONCLUSIONS This study provides the first evidence that GCKR rs780094, a single-nucleotide polymorphism related to diabetes, may be associated with pancreatic cancer risk. Although the results from this analysis are preliminary, there is a biologic plausibility for such an association.
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Doliba NM, Qin W, Najafi H, Liu C, Buettger CW, Sotiris J, Collins HW, Li C, Stanley CA, Wilson DF, Grimsby J, Sarabu R, Naji A, Matschinsky FM. Glucokinase activation repairs defective bioenergetics of islets of Langerhans isolated from type 2 diabetics. Am J Physiol Endocrinol Metab 2012; 302:E87-E102. [PMID: 21952036 PMCID: PMC3328091 DOI: 10.1152/ajpendo.00218.2011] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Accepted: 09/20/2011] [Indexed: 12/31/2022]
Abstract
It was reported previously that isolated human islets from individuals with type 2 diabetes mellitus (T2DM) show reduced glucose-stimulated insulin release. To assess the possibility that impaired bioenergetics may contribute to this defect, glucose-stimulated respiration (Vo(2)), glucose usage and oxidation, intracellular Ca(2+), and insulin secretion (IS) were measured in pancreatic islets isolated from three healthy and three type 2 diabetic organ donors. Isolated mouse and rat islets were studied for comparison. Islets were exposed to a "staircase" glucose stimulus, whereas IR and Vo(2) were measured. Vo(2) of human islets from normals and diabetics increased sigmoidally from equal baselines of 0.25 nmol/100 islets/min as a function of glucose concentration. Maximal Vo(2) of normal islets at 24 mM glucose was 0.40 ± 0.02 nmol·min(-1)·100 islets(-1), and the glucose S(0.5) was 4.39 ± 0.10 mM. The glucose stimulation of respiration of islets from diabetics was lower, V(max) of 0.32 ± 0.01 nmol·min(-1)·100 islets(-1), and the S(0.5) shifted to 5.43 ± 0.13 mM. Glucose-stimulated IS and the rise of intracellular Ca(2+) were also reduced in diabetic islets. A clinically effective glucokinase activator normalized the defective Vo(2), IR, and free calcium responses during glucose stimulation in islets from type 2 diabetics. The body of data shows that there is a clear relationship between the pancreatic islet energy (ATP) production rate and IS. This relationship was similar for normal human, mouse, and rat islets and the data for all species fitted a single sigmoidal curve. The shared threshold rate for IS was ∼13 pmol·min(-1)·islet(-1). Exendin-4, a GLP-1 analog, shifted the ATP production-IS curve to the left and greatly potentiated IS with an ATP production rate threshold of ∼10 pmol·min(-1)·islet(-1). Our data suggest that impaired β-cell bioenergetics resulting in greatly reduced ATP production is critical in the molecular pathogenesis of type 2 diabetes mellitus.
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Affiliation(s)
- Nicolai M Doliba
- Department of Biochemistry and Biophysics, University of Pennsylvania, 415 Curie Blvd., Philadelphia, PA 19104-6140, USA
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38
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Cullen KS, Matschinsky FM, Agius L, Arden C. Susceptibility of glucokinase-MODY mutants to inactivation by oxidative stress in pancreatic β-cells. Diabetes 2011; 60:3175-85. [PMID: 22028181 PMCID: PMC3219952 DOI: 10.2337/db11-0423] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Accepted: 08/31/2011] [Indexed: 12/19/2022]
Abstract
OBJECTIVE The posttranslational regulation of glucokinase (GK) differs in hepatocytes and pancreatic β-cells. We tested the hypothesis that GK mutants that cause maturity-onset diabetes of the young (GK-MODY) show compromised activity and posttranslational regulation in β-cells. RESEARCH DESIGN AND METHODS Activity and protein expression of GK-MODY and persistent hyperinsulinemic hypoglycemia of infancy (PHHI) mutants were studied in β-cell (MIN6) and non-β-cell (H4IIE) models. Binding of GK to phosphofructo-2-kinase, fructose-2,6-bisphosphatase (PFK2/FBPase2) was studied by bimolecular fluorescence complementation in cell-based models. RESULTS Nine of 11 GK-MODY mutants that have minimal effect on enzyme kinetics in vitro showed decreased specific activity relative to wild type when expressed in β-cells. A subset of these were stable in non-β-cells but showed increased inactivation in conditions of oxidative stress and partial reversal of inactivation by dithiothreitol. Unlike the GK-MODY mutants, four of five GK-PHHI mutants had similar specific activity to wild type and Y214C had higher activity than wild type. The GK-binding protein PFK2/FBPase2 protected wild-type GK from oxidative inactivation and the decreased stability of GK-MODY mutants correlated with decreased interaction with PFK2/FBPase2. CONCLUSIONS Several GK-MODY mutants show posttranslational defects in β-cells characterized by increased susceptibility to oxidative stress and/or protein instability. Regulation of GK activity through modulation of thiol status may be a physiological regulatory mechanism for the control of GK activity in β-cells.
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Affiliation(s)
- Kirsty S. Cullen
- Institute of Cellular Medicine, Newcastle University, Newcastle Upon Tyne, U.K
| | - Franz M. Matschinsky
- Department of Biochemistry and Biophysics and Institute for Diabetes, Obesity and Metabolism, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Loranne Agius
- Institute of Cellular Medicine, Newcastle University, Newcastle Upon Tyne, U.K
| | - Catherine Arden
- Institute of Cellular Medicine, Newcastle University, Newcastle Upon Tyne, U.K
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Fenner D, Odili S, Hong HK, Kobayashi Y, Kohsaka A, Siepka SM, Vitaterna MH, Chen P, Zelent B, Grimsby J, Takahashi JS, Matschinsky FM, Bass J. Generation of N-ethyl-N-nitrosourea (ENU) diabetes models in mice demonstrates genotype-specific action of glucokinase activators. J Biol Chem 2011; 286:39560-72. [PMID: 21921030 PMCID: PMC3234779 DOI: 10.1074/jbc.m111.269100] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Revised: 08/16/2011] [Indexed: 11/06/2022] Open
Abstract
We performed genome-wide mutagenesis in C57BL/6J mice using N-ethyl-N-nitrosourea to identify mutations causing high blood glucose early in life and to produce new animal models of diabetes. Of a total of 13 new lines confirmed by heritability testing, we identified two semi-dominant pedigrees with novel missense mutations (Gck(K140E) and Gck(P417R)) in the gene encoding glucokinase (Gck), the mammalian glucose sensor that is mutated in human maturity onset diabetes of the young type 2 and the target of emerging anti-hyperglycemic agents that function as glucokinase activators (GKAs). Diabetes phenotype corresponded with genotype (mild-to-severe: Gck(+/+) < Gck(P417R/+), Gck(K140E)(/+) < Gck(P417R/P417R), Gck(P417R/K140E), and Gck(K140E/K140E)) and with the level of expression of GCK in liver. Each mutant was produced as the recombinant enzyme in Escherichia coli, and analysis of k(cat) and tryptophan fluorescence (I(320/360)) during thermal shift unfolding revealed a correlation between thermostability and the severity of hyperglycemia in the whole animal. Disruption of the glucokinase regulatory protein-binding site (GCK(K140E)), but not the ATP binding cassette (GCK(P417R)), prevented inhibition of enzyme activity by glucokinase regulatory protein and corresponded with reduced responsiveness to the GKA drug. Surprisingly, extracts from liver of diabetic GCK mutants inhibited activity of the recombinant enzyme, a property that was also observed in liver extracts from mice with streptozotocin-induced diabetes. These results indicate a relationship between genotype, phenotype, and GKA efficacy. The integration of forward genetic screening and biochemical profiling opens a pathway for preclinical development of mechanism-based diabetes therapies.
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Affiliation(s)
- Deborah Fenner
- From the Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
- the Department of Neurobiology and Physiology and
| | - Stella Odili
- the Department of Biochemistry and Biophysics, Children's Hospital of Pennsylvania and Diabetes Center, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104
| | - Hee-Kyung Hong
- the Department of Neurobiology and Physiology and
- the Center for Sleep and Circadian Biology, Northwestern University, Evanston, Illinois 60208
| | - Yumiko Kobayashi
- From the Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
- the Department of Neurobiology and Physiology and
| | - Akira Kohsaka
- the Department of Neurobiology and Physiology and
- the Departments of Medicine and Physiology II, Wakayama Medical University, Wakayama City, 640-8265, Japan
| | - Sandra M. Siepka
- the Department of Neurobiology and Physiology and
- the Center for Sleep and Circadian Biology, Northwestern University, Evanston, Illinois 60208
| | - Martha H. Vitaterna
- the Department of Neurobiology and Physiology and
- the Center for Sleep and Circadian Biology, Northwestern University, Evanston, Illinois 60208
| | - Pan Chen
- the Department of Biochemistry and Biophysics, Children's Hospital of Pennsylvania and Diabetes Center, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104
| | - Bogumil Zelent
- the Department of Biochemistry and Biophysics, Children's Hospital of Pennsylvania and Diabetes Center, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104
| | - Joseph Grimsby
- the Department of Metabolic Diseases, Hoffmann-La Roche, Nutley, New Jersey 07110
| | - Joseph S. Takahashi
- the Department of Neurobiology and Physiology and
- the Department of Neuroscience and Howard Hughes Medical Institute, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390, and
| | - Franz M. Matschinsky
- the Department of Biochemistry and Biophysics, Children's Hospital of Pennsylvania and Diabetes Center, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104
| | - Joseph Bass
- From the Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
- the Department of Neurobiology and Physiology and
- the Center for Sleep and Circadian Biology, Northwestern University, Evanston, Illinois 60208
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Steele AM, Tribble ND, Caswell R, Wensley KJ, Hattersley AT, Gloyn AL, Ellard S. The previously reported T342P GCK missense variant is not a pathogenic mutation causing MODY. Diabetologia 2011; 54:2202-5. [PMID: 21604084 DOI: 10.1007/s00125-011-2194-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Accepted: 04/21/2011] [Indexed: 10/18/2022]
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41
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Molnes J, Teigen K, Aukrust I, Bjørkhaug L, Søvik O, Flatmark T, Njølstad PR. Binding of ATP at the active site of human pancreatic glucokinase--nucleotide-induced conformational changes with possible implications for its kinetic cooperativity. FEBS J 2011; 278:2372-86. [PMID: 21569204 PMCID: PMC3531626 DOI: 10.1111/j.1742-4658.2011.08160.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Glucokinase (GK) is the central player in glucose-stimulated insulin release from pancreatic β-cells, and catalytic activation by α-d-glucose binding has a key regulatory function. Whereas the mechanism of this activation is well understood, on the basis of crystal structures of human GK, there are no similar structural data on ATP binding to the ligand-free enzyme and how it affects its conformation. Here, we report on a conformational change induced by the binding of adenine nucleotides to human pancreatic GK, as determined by intrinsic tryptophan fluorescence, using the catalytically inactive mutant form T228M to correct for the inner filter effect. Adenosine-5′-(β,γ-imido)triphosphate and ATP bind to the wild-type enzyme with apparent [L]0.5 (ligand concentration at half-maximal effect) values of 0.27 ± 0.02 mm and 0.78 ± 0.14 mm, respectively. The change in protein conformation was further supported by ATP inhibition of the binding of the fluorescent probe 8-anilino-1-naphthalenesulfonate and limited proteolysis by trypsin, and by molecular dynamic simulations. The simulations provide a first insight into the dynamics of the binary complex with ATP, including motion of the flexible surface/active site loop and partial closure of the active site cleft. In the complex, the adenosine moiety is packed between two α-helices and stabilized by hydrogen bonds (with Thr228, Thr332, and Ser336) and hydrophobic interactions (with Val412 and Leu415). Combined with enzyme kinetic analyses, our data indicate that the ATP-induced changes in protein conformation may have implications for the kinetic cooperativity of the enzyme.
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Affiliation(s)
- Janne Molnes
- Department of Pediatrics, Haukeland University Hospital, Bergen, Norway
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42
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Beer NL, van de Bunt M, Colclough K, Lukacs C, Arundel P, Chik CL, Grimsby J, Ellard S, Gloyn AL. Discovery of a novel site regulating glucokinase activity following characterization of a new mutation causing hyperinsulinemic hypoglycemia in humans. J Biol Chem 2011; 286:19118-26. [PMID: 21454522 DOI: 10.1074/jbc.m111.223362] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Type 2 diabetes is a global problem, and current ineffective therapeutic strategies pave the way for novel treatments like small molecular activators targeting glucokinase (GCK). GCK activity is fundamental to beta cell and hepatocyte glucose metabolism, and heterozygous activating and inactivating GCK mutations cause hyperinsulinemic hypoglycemia (HH) and maturity onset diabetes of the young (MODY) respectively. Over 600 naturally occurring inactivating mutations have been reported, whereas only 13 activating mutations are documented to date. We report two novel GCK HH mutations (V389L and T103S) at residues where MODY mutations also occur (V389D and T103I). Using recombinant proteins with in vitro assays, we demonstrated that both HH mutants had a greater relative activity index than wild type (6.0 for V389L, 8.4 for T103S, and 1.0 for wild type). This was driven by an increased affinity for glucose (S(0.5), 3.3 ± 0.1 and 3.5 ± 0.1 mm, respectively) versus wild type (7.5 ± 0.1 mm). Correspondingly, the V389D and T103I MODY mutants had markedly reduced relative activity indexes (<0.1). T103I had an altered affinity for glucose (S(0.5), 24.9 ± 0.6 mm), whereas V389D also exhibited a reduced affinity for ATP and decreased catalysis rate (S(0.5), 78.6 ± 4.5 mm; ATP(K(m)), 1.5 ± 0.1 mm; K(cat), 10.3 ± 1.1s(-1)) compared with wild type (ATP(K(m)), 0.4 ± <0.1; K(cat), 62.9 ± 1.2). Both Thr-103 mutants showed reduced inhibition by the endogenous hepatic inhibitor glucokinase regulatory protein. Molecular modeling demonstrated that Thr-103 maps to the allosteric activator site, whereas Val-389 is located remotely to this position and all other previously reported activating mutations, highlighting α-helix 11 as a novel region regulating GCK activity. Our data suggest that pharmacological manipulation of GCK activity at locations distal from the allosteric activator site is possible.
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Affiliation(s)
- Nicola L Beer
- Oxford Centre for Diabetes Endocrinology and Metabolism, University of Oxford, Oxford OX3 7LJ, United Kingdom
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Matschinsky FM, Zelent B, Doliba NM, Kaestner KH, Vanderkooi JM, Grimsby J, Berthel SJ, Sarabu R. Research and development of glucokinase activators for diabetes therapy: theoretical and practical aspects. Handb Exp Pharmacol 2011:357-401. [PMID: 21484579 DOI: 10.1007/978-3-642-17214-4_15] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Glucokinase Glucokinase (GK GK ; EC 2.7.1.1.) phosphorylates and regulates glucose metabolism in insulin-producing pancreatic beta-cells, hepatocytes, and certain cells of the endocrine and nervous systems allowing it to play a central role in glucose homeostasis glucose homeostasis . Most importantly, it serves as glucose sensor glucose sensor in pancreatic beta-cells mediating glucose-stimulated insulin biosynthesis and release and it governs the capacity of the liver to convert glucose to glycogen. Activating and inactivating mutations of the glucokinase gene cause autosomal dominant hyperinsulinemic hypoglycemia and hypoinsulinemic hyperglycemia in humans, respectively, illustrating the preeminent role of glucokinase in the regulation of blood glucose and also identifying the enzyme as a potential target for developing antidiabetic drugs antidiabetic drugs . Small molecules called glucokinase activators (GKAs) glucokinase activators (GKAs) which bind to an allosteric activator allosteric activator site of the enzyme have indeed been discovered and hold great promise as new antidiabetic agents. GKAs increase the enzyme's affinity for glucose and also its maximal catalytic rate. Consequently, they stimulate insulin biosynthesis and secretion, enhance hepatic glucose uptake, and augment glucose metabolism and related processes in other glucokinase-expressing cells. Manifestations of these effects, most prominently a lowering of blood glucose, are observed in normal laboratory animals and man but also in animal models of diabetes and patients with type 2 diabetes mellitus (T2DM T2DM ) type 2 diabetes mellitus (T2DM) . These compelling concepts and results sustain a strong R&D effort by many pharmaceutical companies to generate GKAs with characteristics allowing for a novel drug treatment of T2DM.
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Affiliation(s)
- Franz M Matschinsky
- Department of Biochemistry and Biophysics, University of Pennsylvania, Institute for Diabetes, Obesity and Metabolism, 415 Curie Blvd, 605 CRB, Philadelphia, PA 19104, USA.
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Insight into the biochemical characteristics of a novel glucokinase gene mutation. Hum Genet 2010; 129:231-8. [DOI: 10.1007/s00439-010-0914-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Accepted: 11/05/2010] [Indexed: 10/18/2022]
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Kim JY, Song EH, Lee HJ, Oh YK, Park YS, Park JW, Kim BJ, Kim DJ, Lee I, Song J, Kim WH. Chronic ethanol consumption-induced pancreatic {beta}-cell dysfunction and apoptosis through glucokinase nitration and its down-regulation. J Biol Chem 2010; 285:37251-62. [PMID: 20855893 DOI: 10.1074/jbc.m110.142315] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Chronic ethanol consumption is known as an independent risk factor for type 2 diabetes, which is characterized by impaired glucose homeostasis and insulin resistance; however, there is a great deal of controversy concerning the relationships between alcohol consumption and the development of type 2 diabetes. We investigated the effects of chronic ethanol consumption on pancreatic β-cell dysfunction and whether generated peroxynitrite participates in the impaired glucose homeostasis. Here we show that chronic ethanol feeding decreases the ability of pancreatic β-cells to mediate insulin secretion and ATP production in coordination with the decrease of glucokinase, Glut2, and insulin expression. Specific blockade of ATF3 using siRNA or C-terminally deleted ATF3(ΔC) attenuated ethanol-induced pancreatic β-cell apoptosis or dysfunction and restored the down-regulation of glucokinase (GCK), insulin, and pancreatic duodenal homeobox-1 induced by ethanol. GCK inactivation and down-regulation were predominantly mediated by ethanol metabolism-generated peroxynitrite, which were suppressed by the peroxynitrite scavengers N(γ)-monomethyl-L-arginine, uric acid, and deferoxamine but not by the S-nitrosylation inhibitor DTT, indicating that tyrosine nitration is the predominant modification associated with GCK down-regulation and inactivation rather than S-nitrosylation of cysteine. Tyrosine nitration of GCK prevented its association with pBad, and GCK translocation into the mitochondria results in subsequent proteasomal degradation of GCK following ubiquitination. This study identified a novel and efficient pathway by which chronic ethanol consumption may induce GCK down-regulation and inactivation by inducing tyrosine nitration of GCK, resulting in pancreatic β-cell apoptosis and dysfunction. Peroxynitrite-induced ATF3 may also serve as a potent upstream regulator of GCK down-regulation and β-cell apoptosis.
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Affiliation(s)
- Ji Yeon Kim
- Divisions of Metabolic Diseases, National Institutes of Health, Eunpyeong-gu, Seoul 122-701, Korea
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Ralph EC, Sun S. Biochemical characterization of MODY2 glucokinase variants V62M and G72R reveals reduced enzymatic activities relative to wild type. Biochemistry 2010; 48:2514-21. [PMID: 19187021 DOI: 10.1021/bi900020n] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The glucokinase V62M and G72R mutations are naturally occurring and known to associate with hyperglycemia in humans. Structurally, V62 and G72 residues are located in close proximity to the allosteric site where hypoglycemia-linked activating mutations are clustered. To address the mechanism by which these variants alter the physiological phenotype, we characterized the biochemical and biophysical properties of the enzymes. Recombinant proteins were purified without affinity tags, and their steady-state kinetics and glucose binding affinities were determined. Both enzymes showed reduced rates of turnover (k(cat)) and reduced glucose affinity (i.e., increased K(0.5) and K(D) values). Their thermal stability did not largely differ from that of wild-type glucokinase. However, V62M and G72R lost the stabilizing protein interactions with glucokinase regulatory protein, which may contribute to lower activity in vivo. Both mutants were subject to activation by small molecule activators. In conclusion, the decreased enzyme activities of V62M and G72R observed in this study are consistent with the hyperglycemic phenotype.
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Affiliation(s)
- Erik C Ralph
- Department of Biochemical Pharmacology, La Jolla Laboratories, Pfizer Global Research and Development, San Diego, California 92121, USA
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van Bürck L, Blutke A, Kautz S, Rathkolb B, Klaften M, Wagner S, Kemter E, Hrabé de Angelis M, Wolf E, Aigner B, Wanke R, Herbach N. Phenotypic and pathomorphological characteristics of a novel mutant mouse model for maturity-onset diabetes of the young type 2 (MODY 2). Am J Physiol Endocrinol Metab 2010; 298:E512-23. [PMID: 19952346 DOI: 10.1152/ajpendo.00465.2009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Several mutant mouse models for human diseases such as diabetes mellitus have been generated in the large-scale Munich ENU (N-ethyl-N-nitrosourea) mouse mutagenesis project. The aim of this study was to identify the causal mutation of one of these strains and to characterize the resulting diabetic phenotype. Mutants exhibit a T to G transversion mutation at nt 629 in the glucokinase (Gck) gene, leading to an amino acid exchange from methionine to arginine at position 210. Adult Munich Gck(M210R) mutant mice demonstrated a significant reduction of hepatic glucokinase enzyme activity but equal glucokinase mRNA and protein abundances. While homozygous mutant mice exhibited growth retardation and died soon after birth in consequence of severe hyperglycemia, heterozygous mutant mice displayed only slightly elevated blood glucose levels, present from birth, with development of disturbed glucose tolerance and glucose-induced insulin secretion. Additionally, insulin sensitivity and fasting serum insulin levels were slightly reduced in male mutant mice from an age of 90 days onward. While beta-cell mass was unaltered in neonate heterozygous and homozygous mutant mice, the total islet and beta-cell volumes and the total volume of isolated beta-cells were significantly decreased in 210-day-old male, but not female heterozygous mutant mice despite undetectable apoptosis. These findings indicate that reduced total islet and beta-cell volumes of male mutants might emerge from disturbed postnatal islet neogenesis. Considering the lack of knowledge about the pathomorphology of maturity-onset diabetes of the young type 2 (MODY 2), this glucokinase mutant model of reduced total islet and total beta-cell volume provides the opportunity to elucidate the impact of a defective glucokinase on development and maintenance of beta-cell mass and its relevance in MODY 2 patients.
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Affiliation(s)
- L van Bürck
- Inst. of Veterinary Pathology, Center for Clinical Veterinary Medicine, Munich, Germany.
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Osbak KK, Colclough K, Saint-Martin C, Beer NL, Bellanné-Chantelot C, Ellard S, Gloyn AL. Update on mutations in glucokinase (GCK), which cause maturity-onset diabetes of the young, permanent neonatal diabetes, and hyperinsulinemic hypoglycemia. Hum Mutat 2010; 30:1512-26. [PMID: 19790256 DOI: 10.1002/humu.21110] [Citation(s) in RCA: 339] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Glucokinase is a key regulatory enzyme in the pancreatic beta-cell. It plays a crucial role in the regulation of insulin secretion and has been termed the glucose sensor in pancreatic beta-cells. Given its central role in the regulation of insulin release it is understandable that mutations in the gene encoding glucokinase (GCK) can cause both hyper- and hypoglycemia. Heterozygous inactivating mutations in GCK cause maturity-onset diabetes of the young (MODY) subtype glucokinase (GCK), characterized by mild fasting hyperglycemia, which is present at birth but often only detected later in life during screening for other purposes. Homozygous inactivating GCK mutations result in a more severe phenotype presenting at birth as permanent neonatal diabetes mellitus (PNDM). A growing number of heterozygous activating GCK mutations that cause hypoglycemia have also been reported. A total of 620 mutations in the GCK gene have been described in a total of 1,441 families. There are no common mutations, and the mutations are distributed throughout the gene. The majority of activating mutations cluster in a discrete region of the protein termed the allosteric activator site. The identification of a GCK mutation in patients with both hyper- and hypoglycemia has implications for the clinical course and clinical management of their disorder.
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Affiliation(s)
- Kara K Osbak
- Diabetes Research Laboratories, Oxford Centre for Diabetes Endocrinology & Metabolism, University of Oxford, United Kingdom
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Abstract
Glucokinase, a unique isoform of the hexokinase enzymes, which are known to phosphorylate D-glucose and other hexoses, was identified during the past three to four decades as a new, promising drug target for type 2 diabetes. Glucokinase serves as a glucose sensor of the insulin-producing pancreatic islet beta-cells, controls the conversion of glucose to glycogen in the liver and regulates hepatic glucose production. Guided by this fundamental knowledge, several glucokinase activators are now being developed, and have so far been shown to lower blood glucose in several animal models of type 2 diabetes and in initial trials in humans with the disease. Here, the scientific basis and current status of this new approach to diabetes therapy are discussed.
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Sagen JV, Bjørkhaug L, Molnes J, Raeder H, Grevle L, Søvik O, Molven A, Njølstad PR. Diagnostic screening of MODY2/GCK mutations in the Norwegian MODY Registry. Pediatr Diabetes 2008; 9:442-9. [PMID: 18399931 DOI: 10.1111/j.1399-5448.2008.00399.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND Maturity-onset diabetes of the young, type 2 (MODY2) is caused by mutations in the glucokinase gene (GCK). The aim of our study was to determine the prevalence of GCK mutations in the Norwegian MODY Registry and to delineate the clinical phenotype of identified GCK mutation carriers. METHODS We screened 122 probands referred to the MODY Registry for mutations in GCK and studied extended families with MODY2. RESULTS We found 2 novel (S76Y and N231S) and 13 previously reported (V62A, G72R, L146R, R191W, A208T, M210K, Y215X, M235T, R275C, E339G, R377C, S453L, and IVS5+1G>C) GCK mutations in 23 probands and in their 33 family members. The prevalence of MODY2 was 12% in the Norwegian MODY Registry. The subjects with GCK mutations had features of mild diabetes. Yet, 15 of 56 MODY2 subjects were treated with oral drugs or insulin. Three subjects had retinopathy and one had macrovascular disease. Also, a limited number of cases had elevated fasting serum triglyceride values. Moreover, two GCK mutation carriers were diagnosed with type 1 diabetes. CONCLUSIONS According to our diagnostic screening of GCK in the MODY Registry, MODY2 is less prevalent than MODY3 in Norway but is likely to be underreported. Recognizing MODY2 in diabetic patients is important in order to prevent overtreatment. Finally, our study demonstrates the co-occurrence of MODY2 in families with type 1 or type 2 diabetes.
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Affiliation(s)
- Jørn V Sagen
- Section for Endocrinology, Institute of Medicine, University of Bergen, Bergen, Norway
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