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Galli A, Moretti S, Dule N, Di Cairano ES, Castagna M, Marciani P, Battaglia C, Bertuzzi F, Fiorina P, Pastore I, La Rosa S, Davalli A, Folli F, Perego C. Hyperglycemia impairs EAAT2 glutamate transporter trafficking and glutamate clearance in islets of Langerhans: implications for type 2 diabetes pathogenesis and treatment. Am J Physiol Endocrinol Metab 2024; 327:E27-E41. [PMID: 38690938 PMCID: PMC11390119 DOI: 10.1152/ajpendo.00069.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Revised: 04/18/2024] [Accepted: 04/21/2024] [Indexed: 05/03/2024]
Abstract
Pancreatic endocrine cells employ a sophisticated system of paracrine and autocrine signals to synchronize their activities, including glutamate, which controls hormone release and β-cell viability by acting on glutamate receptors expressed by endocrine cells. We here investigate whether alteration of the excitatory amino acid transporter 2 (EAAT2), the major glutamate clearance system in the islet, may occur in type 2 diabetes mellitus and contribute to β-cell dysfunction. Increased EAAT2 intracellular localization was evident in islets of Langerhans from T2DM subjects as compared with healthy control subjects, despite similar expression levels. Chronic treatment of islets from healthy donors with high-glucose concentrations led to the transporter internalization in vesicular compartments and reduced [H3]-d-glutamate uptake (65 ± 5% inhibition), phenocopying the findings in T2DM pancreatic sections. The transporter relocalization was associated with decreased Akt phosphorylation protein levels, suggesting an involvement of the phosphoinositide 3-kinase (PI3K)/Akt pathway in the process. In line with this, PI3K inhibition by a 100-µM LY294002 treatment in human and clonal β-cells caused the transporter relocalization in intracellular compartments and significantly reduced the glutamate uptake compared to control conditions, suggesting that hyperglycemia changes the trafficking of the transporter to the plasma membrane. Upregulation of the glutamate transporter upon treatment with the antibiotic ceftriaxone rescued hyperglycemia-induced β-cells dysfunction and death. Our data underscore the significance of EAAT2 in regulating islet physiology and provide a rationale for potential therapeutic targeting of this transporter to preserve β-cell survival and function in diabetes.NEW & NOTEWORTHY The glutamate transporter SLC1A2/excitatory amino acid transporter 2 (EAAT2) is expressed on the plasma membrane of pancreatic β-cells and controls islet glutamate clearance and β-cells survival. We found that the EAAT2 membrane expression is lost in the islets of Langerhans from type 2 diabetes mellitus (T2DM) patients due to hyperglycemia-induced downregulation of the phosphoinositide 3-kinase/Akt pathway and modification of its intracellular trafficking. Pharmacological rescue of EAAT2 expression prevents β-cell dysfunction and death, suggesting EAAT2 as a new potential target of intervention in T2DM.
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Affiliation(s)
- Alessandra Galli
- Laboratory of Molecular and Cellular Physiology, Department of Excellence of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Milan, Italy
| | - Stefania Moretti
- Laboratory of Molecular and Cellular Physiology, Department of Excellence of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Milan, Italy
| | - Nevia Dule
- Laboratory of Molecular and Cellular Physiology, Department of Excellence of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Milan, Italy
| | - Eliana Sara Di Cairano
- Laboratory of Molecular and Cellular Physiology, Department of Excellence of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Milan, Italy
| | - Michela Castagna
- Laboratory of Molecular and Cellular Physiology, Department of Excellence of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Milan, Italy
| | - Paola Marciani
- Laboratory of Molecular and Cellular Physiology, Department of Excellence of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Milan, Italy
| | - Cristina Battaglia
- Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano, Milan, Italy
| | | | - Paolo Fiorina
- Department of Biomedical and Clinical Sciences "L. Sacco,"Università degli Studi di Milano, Milan, Italy
- Endocrinology Unit, ASST Fatebenefratelli-Sacco, Milan, Italy
| | - Ida Pastore
- Endocrinology Unit, ASST Fatebenefratelli-Sacco, Milan, Italy
| | - Stefano La Rosa
- Unit of Pathology, Department of Oncology, ASST Sette Laghi, Varese, Italy
- Department of Medicine and Technological Innovation, Università degli Studi dell'Insubria, Varese, Italy
| | - Alberto Davalli
- Diabetes and Endocrinology Unit, Department of Internal Medicine, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Franco Folli
- Department of Health Sciences, Università degli Studi di Milano, Milan, Italy
| | - Carla Perego
- Laboratory of Molecular and Cellular Physiology, Department of Excellence of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Milan, Italy
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2
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Grandl G, Collden G, Feng J, Bhattacharya S, Klingelhuber F, Schomann L, Bilekova S, Ansarullah, Xu W, Far FF, Tost M, Gruber T, Bastidas-Ponce A, Zhang Q, Novikoff A, Liskiewicz A, Liskiewicz D, Garcia-Caceres C, Feuchtinger A, Tschöp MH, Krahmer N, Lickert H, Müller TD. Global, neuronal or β cell-specific deletion of inceptor improves glucose homeostasis in male mice with diet-induced obesity. Nat Metab 2024; 6:448-457. [PMID: 38418586 DOI: 10.1038/s42255-024-00991-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 01/19/2024] [Indexed: 03/01/2024]
Abstract
Insulin resistance is an early complication of diet-induced obesity (DIO)1, potentially leading to hyperglycaemia and hyperinsulinaemia, accompanied by adaptive β cell hypertrophy and development of type 2 diabetes2. Insulin not only signals via the insulin receptor (INSR), but also promotes β cell survival, growth and function via the insulin-like growth factor 1 receptor (IGF1R)3-6. We recently identified the insulin inhibitory receptor (inceptor) as the key mediator of IGF1R and INSR desensitization7. But, although β cell-specific loss of inceptor improves β cell function in lean mice7, it warrants clarification whether inceptor signal inhibition also improves glycaemia under conditions of obesity. We assessed the glucometabolic effects of targeted inceptor deletion in either the brain or the pancreatic β cells under conditions of DIO in male mice. In the present study, we show that global and neuronal deletion of inceptor, as well as its adult-onset deletion in the β cells, improves glucose homeostasis by enhancing β cell health and function. Moreover, we demonstrate that inceptor-mediated improvement in glucose control does not depend on inceptor function in agouti-related protein-expressing or pro-opiomelanocortin neurons. Our data demonstrate that inceptor inhibition improves glucose homeostasis in mice with DIO, hence corroborating that inceptor is a crucial regulator of INSR and IGF1R signalling.
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Affiliation(s)
- Gerald Grandl
- Institute of Diabetes and Obesity, Helmholtz Center Munich, Neuherberg, Germany
- German Center for Diabetes Research, Neuherberg, Germany
| | - Gustav Collden
- Institute of Diabetes and Obesity, Helmholtz Center Munich, Neuherberg, Germany
- German Center for Diabetes Research, Neuherberg, Germany
| | - Jin Feng
- German Center for Diabetes Research, Neuherberg, Germany
- Institute of Diabetes and Regeneration Research, Helmholtz Center Munich, Neuherberg, Germany
- School of Medicine, Technische Universität München, Munich, Germany
| | - Sreya Bhattacharya
- German Center for Diabetes Research, Neuherberg, Germany
- Institute of Diabetes and Regeneration Research, Helmholtz Center Munich, Neuherberg, Germany
- School of Medicine, Technische Universität München, Munich, Germany
| | - Felix Klingelhuber
- Institute of Diabetes and Obesity, Helmholtz Center Munich, Neuherberg, Germany
- German Center for Diabetes Research, Neuherberg, Germany
| | - Leopold Schomann
- German Center for Diabetes Research, Neuherberg, Germany
- Institute of Diabetes and Regeneration Research, Helmholtz Center Munich, Neuherberg, Germany
| | - Sara Bilekova
- German Center for Diabetes Research, Neuherberg, Germany
- Institute of Diabetes and Regeneration Research, Helmholtz Center Munich, Neuherberg, Germany
| | - Ansarullah
- German Center for Diabetes Research, Neuherberg, Germany
- Institute of Diabetes and Regeneration Research, Helmholtz Center Munich, Neuherberg, Germany
| | - Weiwei Xu
- German Center for Diabetes Research, Neuherberg, Germany
- Institute of Diabetes and Regeneration Research, Helmholtz Center Munich, Neuherberg, Germany
| | - Fataneh Fathi Far
- German Center for Diabetes Research, Neuherberg, Germany
- Institute of Diabetes and Regeneration Research, Helmholtz Center Munich, Neuherberg, Germany
| | - Monica Tost
- Core Facility Pathology & Tissue Analytics, Helmholtz Center Munich, Munich, Germany
| | - Tim Gruber
- Institute of Diabetes and Obesity, Helmholtz Center Munich, Neuherberg, Germany
- German Center for Diabetes Research, Neuherberg, Germany
| | - Aimée Bastidas-Ponce
- German Center for Diabetes Research, Neuherberg, Germany
- Institute of Diabetes and Regeneration Research, Helmholtz Center Munich, Neuherberg, Germany
| | - Qian Zhang
- Institute of Diabetes and Obesity, Helmholtz Center Munich, Neuherberg, Germany
- German Center for Diabetes Research, Neuherberg, Germany
| | - Aaron Novikoff
- Institute of Diabetes and Obesity, Helmholtz Center Munich, Neuherberg, Germany
- German Center for Diabetes Research, Neuherberg, Germany
| | - Arkadiusz Liskiewicz
- Institute of Diabetes and Obesity, Helmholtz Center Munich, Neuherberg, Germany
- German Center for Diabetes Research, Neuherberg, Germany
| | - Daniela Liskiewicz
- Institute of Diabetes and Obesity, Helmholtz Center Munich, Neuherberg, Germany
- German Center for Diabetes Research, Neuherberg, Germany
| | - Cristina Garcia-Caceres
- Institute of Diabetes and Obesity, Helmholtz Center Munich, Neuherberg, Germany
- German Center for Diabetes Research, Neuherberg, Germany
- Medizinische Klinik und Poliklinik IV, Klinikum der Universität, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Annette Feuchtinger
- Core Facility Pathology & Tissue Analytics, Helmholtz Center Munich, Munich, Germany
| | - Matthias H Tschöp
- German Center for Diabetes Research, Neuherberg, Germany
- School of Medicine, Technische Universität München, Munich, Germany
- Helmholtz Zentrum München, Neuherberg, Germany
| | - Natalie Krahmer
- Institute of Diabetes and Obesity, Helmholtz Center Munich, Neuherberg, Germany
- German Center for Diabetes Research, Neuherberg, Germany
| | - Heiko Lickert
- German Center for Diabetes Research, Neuherberg, Germany.
- Institute of Diabetes and Regeneration Research, Helmholtz Center Munich, Neuherberg, Germany.
- School of Medicine, Technische Universität München, Munich, Germany.
| | - Timo D Müller
- Institute of Diabetes and Obesity, Helmholtz Center Munich, Neuherberg, Germany.
- German Center for Diabetes Research, Neuherberg, Germany.
- Walther-Straub Institute of Pharmacology and Toxicology, LMU Munich, Munich, Germany.
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3
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Yu SS, Du JL. Current views on selenoprotein S in the pathophysiological processes of diabetes-induced atherosclerosis: potential therapeutics and underlying biomarkers. Diabetol Metab Syndr 2024; 16:5. [PMID: 38172976 PMCID: PMC10763436 DOI: 10.1186/s13098-023-01247-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 12/24/2023] [Indexed: 01/05/2024] Open
Abstract
Atherosclerotic cardiovascular disease (ASCVD) consistently ranks as the primary mortality factor among diabetic people. A thorough comprehension of the pathophysiological routes and processes activated by atherosclerosis (AS) caused by diabetes mellitus (DM), together with the recognition of new contributing factors, could lead to the discovery of crucial biomarkers and the development of innovative drugs against atherosclerosis. Selenoprotein S (SELENOS) has been implicated in the pathology and progression of numerous conditions, including diabetes, dyslipidemia, obesity, and insulin resistance (IR)-all recognized contributors to endothelial dysfunction (ED), a precursor event to diabetes-induced AS. Hepatic-specific deletion of SELENOS accelerated the onset and progression of obesity, impaired glucose tolerance and insulin sensitivity, and increased hepatic triglycerides (TG) and diacylglycerol (DAG) accumulation; SELENOS expression in subcutaneous and omental adipose tissue was elevated in obese human subjects, and act as a positive regulator for adipogenesis in 3T3-L1 preadipocytes; knockdown of SELENOS in Min6 β-cells induced β-cell apoptosis and reduced cell proliferation. SELENOS also participates in the early stages of AS, notably by enhancing endothelial function, curbing the expression of adhesion molecules, and lessening leukocyte recruitment-actions that collectively reduce the formation of foam cells. Furthermore, SELENOS forestalls the apoptosis of vascular smooth muscle cells (VSMCs) and macrophages, mitigates vascular calcification, and alleviates inflammation in macrophages and CD4+ T cells. These actions help stifle the creation of unstable plaque characterized by thinner fibrous caps, larger necrotic cores, heightened inflammation, and more extensive vascular calcification-features seen in advanced atherosclerotic lesion development. Additionally, serum SELENOS could function as a potential biomarker, and SELENOS single nucleotide polymorphisms (SNPs) rs4965814, rs28628459, and rs9806366, might be effective gene markers for atherosclerosis-related diseases in diabetes. This review accentuates the pathophysiological processes of atherosclerosis in diabetes and amasses current evidence on SELENOS's potential therapeutic benefits or as predictive biomarkers in the various stages of diabetes-induced atherosclerosis.
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Affiliation(s)
- Shan-Shan Yu
- Department of Endocrinology and Metabolism, The First Affiliated Hospital of Dalian Medical University, Dalian, 116011, Liaoning, China
- Dalian Key Laboratory of Prevention and Treatment of Metabolic Diseases and the Vascular Complications, Dalian, 116011, Liaoning, China
| | - Jian-Ling Du
- Department of Endocrinology and Metabolism, The First Affiliated Hospital of Dalian Medical University, Dalian, 116011, Liaoning, China.
- Dalian Key Laboratory of Prevention and Treatment of Metabolic Diseases and the Vascular Complications, Dalian, 116011, Liaoning, China.
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4
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Cota P, Caliskan ÖS, Bastidas-Ponce A, Jing C, Jaki J, Saber L, Czarnecki O, Taskin D, Blöchinger AK, Kurth T, Sterr M, Burtscher I, Krahmer N, Lickert H, Bakhti M. Insulin regulates human pancreatic endocrine cell differentiation in vitro. Mol Metab 2024; 79:101853. [PMID: 38103636 PMCID: PMC10765254 DOI: 10.1016/j.molmet.2023.101853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 11/21/2023] [Accepted: 12/11/2023] [Indexed: 12/19/2023] Open
Abstract
OBJECTIVE The consequences of mutations in genes associated with monogenic forms of diabetes on human pancreas development cannot be studied in a time-resolved fashion in vivo. More specifically, if recessive mutations in the insulin gene influence human pancreatic endocrine lineage formation is still an unresolved question. METHODS To model the extremely reduced insulin levels in patients with recessive insulin gene mutations, we generated a novel knock-in H2B-Cherry reporter human induced pluripotent stem cell (iPSC) line expressing no insulin upon differentiation to stem cell-derived (SC-) β cells in vitro. Differentiation of iPSCs into the pancreatic and endocrine lineage, combined with immunostaining, Western blotting and proteomics analysis phenotypically characterized the insulin gene deficiency in SC-islets. Furthermore, we leveraged FACS analysis and confocal microscopy to explore the impact of insulin shortage on human endocrine cell induction, composition, differentiation and proliferation. RESULTS Interestingly, insulin-deficient SC-islets exhibited low insulin receptor (IR) signaling when stimulated with glucose but displayed increased IR sensitivity upon treatment with exogenous insulin. Furthermore, insulin shortage did not alter neurogenin-3 (NGN3)-mediated endocrine lineage induction. Nevertheless, lack of insulin skewed the SC-islet cell composition with an increased number in SC-β cell formation at the expense of SC-α cells. Finally, insulin deficiency reduced the rate of SC-β cell proliferation but had no impact on the expansion of SC-α cells. CONCLUSIONS Using iPSC disease modelling, we provide first evidence of insulin function in human pancreatic endocrine lineage formation. These findings help to better understand the phenotypic impact of recessive insulin gene mutations during pancreas development and shed light on insulin gene function beside its physiological role in blood glucose regulation.
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Affiliation(s)
- Perla Cota
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany; School of Medicine, Technical University of Munich (TUM), Munich, Germany
| | - Özüm Sehnaz Caliskan
- German Center for Diabetes Research (DZD), Neuherberg, Germany; Institute of Diabetes and Obesity, Helmholtz Munich, Neuherberg, Germany
| | - Aimée Bastidas-Ponce
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - Changying Jing
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany; Munich medical research school (MMRS), Ludwig Maximilian University (LMU), Munich, Germany
| | - Jessica Jaki
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - Lama Saber
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany; School of Medicine, Technical University of Munich (TUM), Munich, Germany
| | - Oliver Czarnecki
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany; School of Medicine, Technical University of Munich (TUM), Munich, Germany
| | - Damla Taskin
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany
| | - Anna Karolina Blöchinger
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - Thomas Kurth
- Center for Molecular and Cellular Bioengineering (CMCB), Technology Platform Core Facility Electron Microscopy and Histology, Technische Universität Dresden, Dresden, Germany
| | - Michael Sterr
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - Ingo Burtscher
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - Natalie Krahmer
- German Center for Diabetes Research (DZD), Neuherberg, Germany; Institute of Diabetes and Obesity, Helmholtz Munich, Neuherberg, Germany
| | - Heiko Lickert
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany; School of Medicine, Technical University of Munich (TUM), Munich, Germany.
| | - Mostafa Bakhti
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany.
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Marafie SK, Al-Mulla F. An Overview of the Role of Furin in Type 2 Diabetes. Cells 2023; 12:2407. [PMID: 37830621 PMCID: PMC10571965 DOI: 10.3390/cells12192407] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Accepted: 09/27/2023] [Indexed: 10/14/2023] Open
Abstract
Post-translational modifications (PTMs) play important roles in regulating several human diseases, like cancer, neurodegenerative disorders, and metabolic disorders. Investigating PTMs' contribution to protein functions is critical for modern biology and medicine. Proprotein convertases (PCs) are irreversible post-translational modifiers that have been extensively studied and are considered as key targets for novel therapeutics. They cleave proteins at specific sites causing conformational changes affecting their functions. Furin is considered as a PC model in regulating growth factors and is involved in regulating many pro-proteins. The mammalian target of the rapamycin (mTOR) signaling pathway is another key player in regulating cellular processes and its dysregulation is linked to several diseases including type 2 diabetes (T2D). The role of furin in the context of diabetes has been rarely explored and is currently lacking. Moreover, furin variants have altered activity that could have implications on overall health. In this review, we aim to highlight the role of furin in T2D in relation to mTOR signaling. We will also address furin genetic variants and their potential effect on T2D and β-cell functions. Understanding the role of furin in prediabetes and dissecting it from other confounding factors like obesity is crucial for future therapeutic interventions in metabolic disorders.
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Affiliation(s)
- Sulaiman K. Marafie
- Biochemistry and Molecular Biology Department, Dasman Diabetes Institute, P.O. Box 1180, Dasman 15462, Kuwait
| | - Fahd Al-Mulla
- Genetics and Bioinformatics Department, Dasman Diabetes Institute, P.O. Box 1180, Dasman 15462, Kuwait
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6
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Biondi G, Marrano N, Dipaola L, Borrelli A, Rella M, D'Oria R, Genchi VA, Caccioppoli C, Porreca I, Cignarelli A, Perrini S, Marchetti P, Vincenti L, Laviola L, Giorgino F, Natalicchio A. The p66Shc Protein Mediates Insulin Resistance and Secretory Dysfunction in Pancreatic β-Cells Under Lipotoxic Conditions. Diabetes 2022; 71:1763-1771. [PMID: 35612429 DOI: 10.2337/db21-1066] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 05/16/2022] [Indexed: 11/13/2022]
Abstract
We evaluated the role of the p66Shc redox adaptor protein in pancreatic β-cell insulin resistance that develops under lipotoxic conditions and with excess body fat. Prolonged exposure to palmitate in vitro or the presence of overweight/obesity augmented p66Shc expression levels and caused an impaired ability of exogenous insulin to increase cellular insulin content and secreted C-peptide levels in INS-1E cells and human and murine islets. In INS-1E cells, p66Shc knockdown resulted in enhanced insulin-induced augmentation of insulin content and C-peptide secretion and prevented the ability of palmitate to impair these effects of insulin. Conversely, p66Shc overexpression impaired insulin-induced augmentation of insulin content and C-peptide secretion in both the absence and presence of palmitate. Under lipotoxic condition, the effects of p66Shc are mediated by a p53-induced increase in p66Shc protein levels and JNK-induced p66Shc phosphorylation at Ser36 and appear to involve the phosphorylation of the ribosomal protein S6 kinase at Thr389 and of insulin receptor substrate 1 at Ser307, resulting in the inhibition of insulin-stimulated protein kinase B phosphorylation at Ser473. Thus, the p66Shc protein mediates the impaired β-cell function and insulin resistance induced by saturated fatty acids and excess body fat.
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Affiliation(s)
- Giuseppina Biondi
- Department of Emergency and Organ Transplantation, University of Bari, Bari, Italy
| | - Nicola Marrano
- Department of Emergency and Organ Transplantation, University of Bari, Bari, Italy
| | - Lucia Dipaola
- Department of Emergency and Organ Transplantation, University of Bari, Bari, Italy
| | - Anna Borrelli
- Department of Emergency and Organ Transplantation, University of Bari, Bari, Italy
| | - Martina Rella
- Department of Emergency and Organ Transplantation, University of Bari, Bari, Italy
| | - Rossella D'Oria
- Department of Emergency and Organ Transplantation, University of Bari, Bari, Italy
| | - Valentina A Genchi
- Department of Emergency and Organ Transplantation, University of Bari, Bari, Italy
| | - Cristina Caccioppoli
- Department of Emergency and Organ Transplantation, University of Bari, Bari, Italy
| | - Immacolata Porreca
- Genetic Research Centre "Gaetano Salvatore" BioGeM, Ariano Irpino, Italy
| | - Angelo Cignarelli
- Department of Emergency and Organ Transplantation, University of Bari, Bari, Italy
| | - Sebastio Perrini
- Department of Emergency and Organ Transplantation, University of Bari, Bari, Italy
| | - Piero Marchetti
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Leonardo Vincenti
- Division of General Surgery, University Hospital Polyclinic, Bari, Italy
| | - Luigi Laviola
- Department of Emergency and Organ Transplantation, University of Bari, Bari, Italy
| | - Francesco Giorgino
- Department of Emergency and Organ Transplantation, University of Bari, Bari, Italy
| | - Annalisa Natalicchio
- Department of Emergency and Organ Transplantation, University of Bari, Bari, Italy
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Dos Santos T, Galipeau M, Schukarucha Gomes A, Greenberg M, Larsen M, Lee D, Maghera J, Mulchandani CM, Patton M, Perera I, Polishevska K, Ramdass S, Shayeganpour K, Vafaeian K, Van Allen K, Wang Y, Weisz T, Estall JL, Mulvihill EE, Screaton RA. Islet Biology During COVID-19: Progress and Perspectives. Can J Diabetes 2022; 46:419-427. [PMID: 35589534 PMCID: PMC8608413 DOI: 10.1016/j.jcjd.2021.11.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 09/28/2021] [Accepted: 11/01/2021] [Indexed: 01/08/2023]
Abstract
The coronavirus-2019 (COVID-19) pandemic has had significant impact on research directions and productivity in the past 2 years. Despite these challenges, since 2020, more than 2,500 peer-reviewed articles have been published on pancreatic islet biology. These include updates on the roles of isocitrate dehydrogenase, pyruvate kinase and incretin hormones in insulin secretion, as well as the discovery of inceptor and signalling by circulating RNAs. The year 2020 also brought advancements in in vivo and in vitro models, including a new transgenic mouse for assessing beta-cell proliferation, a "pancreas-on-a-chip" to study glucose-stimulated insulin secretion and successful genetic editing of primary human islet cells. Islet biologists evaluated the functionality of stem-cell-derived islet-like cells coated with semipermeable biomaterials to prevent autoimmune attack, revealing the importance of cell maturation after transplantation. Prompted by observations that COVID-19 symptoms can worsen for people with obesity or diabetes, researchers examined how islets are directly affected by severe acute respiratory syndrome coronavirus 2. Herein, we highlight novel functional insights, technologies and therapeutic approaches that emerged between March 2020 and July 2021, written for both scientific and lay audiences. We also include a response to these advancements from patient stakeholders, to help lend a broader perspective to developments and challenges in islet research.
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Affiliation(s)
- Theodore Dos Santos
- Alberta Diabetes Institute & Department of Pharmacology, Li Ka Shing Centre for Health Research Innovation, University of Alberta, Edmonton, Alberta, Canada
| | - Maria Galipeau
- Department of Molecular Biology, Faculté de Médecine, Université de Montréal, Montréal, Québec, Canada; Institut de recherches cliniques de Montréal, Cardiometabolic Disease Centre, Montréal, Québec, Canada
| | - Amanda Schukarucha Gomes
- Alberta Diabetes Institute & Department of Pharmacology, Li Ka Shing Centre for Health Research Innovation, University of Alberta, Edmonton, Alberta, Canada
| | | | | | - Daniel Lee
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta, Canada
| | - Jasmine Maghera
- Alberta Diabetes Institute & Department of Pharmacology, Li Ka Shing Centre for Health Research Innovation, University of Alberta, Edmonton, Alberta, Canada
| | | | - Megan Patton
- Toronto General Hospital, Toronto, Ontario, Canada
| | - Ineli Perera
- Department of Biology and Institute of Biochemistry, Carleton University, Ottawa, Ontario, Canada
| | - Kateryna Polishevska
- Alberta Diabetes Institute and Department of Surgery, University of Alberta, Edmonton, Alberta, Canada
| | | | - Kasra Shayeganpour
- Alberta Diabetes Institute and Department of Surgery, University of Alberta, Edmonton, Alberta, Canada
| | | | - Kyle Van Allen
- Department of Biology and Institute of Biochemistry, Carleton University, Ottawa, Ontario, Canada
| | - Yufeng Wang
- University Health Network, Institute of Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
| | - Tom Weisz
- Toronto General Hospital, Toronto, Ontario, Canada
| | - Jennifer L Estall
- Department of Molecular Biology, Faculté de Médecine, Université de Montréal, Montréal, Québec, Canada; Institut de recherches cliniques de Montréal, Cardiometabolic Disease Centre, Montréal, Québec, Canada
| | - Erin E Mulvihill
- Energy Substrate Laboratory, University of Ottawa Heart Institute, Ottawa, Ontario, Canada; Department of Biochemistry, Immunology and Microbiology, University of Ottawa, Ottawa, Ontario, Canada
| | - Robert A Screaton
- Sunnybrook Research Institute, Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada.
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8
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Inceptor counteracts insulin signalling in β-cells to control glycaemia. Nature 2021; 590:326-331. [DOI: 10.1038/s41586-021-03225-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 12/14/2020] [Indexed: 12/13/2022]
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9
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Nagao M, Esguerra JLS, Asai A, Ofori JK, Edlund A, Wendt A, Sugihara H, Wollheim CB, Oikawa S, Eliasson L. Potential Protection Against Type 2 Diabetes in Obesity Through Lower CD36 Expression and Improved Exocytosis in β-Cells. Diabetes 2020; 69:1193-1205. [PMID: 32198214 PMCID: PMC7243297 DOI: 10.2337/db19-0944] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Accepted: 03/09/2020] [Indexed: 12/18/2022]
Abstract
Obesity is a risk factor for type 2 diabetes (T2D); however, not all obese individuals develop the disease. In this study, we aimed to investigate the cause of differential insulin secretion capacity of pancreatic islets from donors with T2D and non-T2D (ND), especially obese donors (BMI ≥30 kg/m2). Islets from obese donors with T2D had reduced insulin secretion, decreased β-cell exocytosis, and higher expression of fatty acid translocase CD36. We tested the hypothesis that CD36 is a key molecule in the reduced insulin secretion capacity. Indeed, CD36 overexpression led to decreased insulin secretion, impaired exocytosis, and reduced granule docking. This was accompanied by reduced expression of the exocytotic proteins SNAP25, STXBP1, and VAMP2, likely because CD36 induced downregulation of the insulin receptor substrate (IRS) proteins, suppressed the insulin-signaling phosphatidylinositol 3-kinase/AKT pathway, and increased nuclear localization of the transcription factor FoxO1. CD36 antibody treatment of the human β-cell line EndoC-βH1 increased IRS1 and exocytotic protein levels, improved granule docking, and enhanced insulin secretion. Our results demonstrate that β-cells from obese donors with T2D have dysfunctional exocytosis likely due to an abnormal lipid handling represented by differential CD36 expression. Hence, CD36 could be a key molecule to limit β-cell function in T2D associated with obesity.
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Affiliation(s)
- Mototsugu Nagao
- Department of Clinical Sciences, Malmö, Islet Cell Exocytosis, Lund University Diabetes Centre, Lund University, Clinical Research Centre, Malmö, Sweden
- Department of Endocrinology, Diabetes and Metabolism, Graduate School of Medicine, Nippon Medical School, Tokyo, Japan
| | - Jonathan L S Esguerra
- Department of Clinical Sciences, Malmö, Islet Cell Exocytosis, Lund University Diabetes Centre, Lund University, Clinical Research Centre, Malmö, Sweden
| | - Akira Asai
- Department of Clinical Sciences, Malmö, Islet Cell Exocytosis, Lund University Diabetes Centre, Lund University, Clinical Research Centre, Malmö, Sweden
- Department of Endocrinology, Diabetes and Metabolism, Graduate School of Medicine, Nippon Medical School, Tokyo, Japan
- Food and Health Science Research Unit, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Jones K Ofori
- Department of Clinical Sciences, Malmö, Islet Cell Exocytosis, Lund University Diabetes Centre, Lund University, Clinical Research Centre, Malmö, Sweden
| | - Anna Edlund
- Department of Clinical Sciences, Malmö, Islet Cell Exocytosis, Lund University Diabetes Centre, Lund University, Clinical Research Centre, Malmö, Sweden
| | - Anna Wendt
- Department of Clinical Sciences, Malmö, Islet Cell Exocytosis, Lund University Diabetes Centre, Lund University, Clinical Research Centre, Malmö, Sweden
| | - Hitoshi Sugihara
- Department of Endocrinology, Diabetes and Metabolism, Graduate School of Medicine, Nippon Medical School, Tokyo, Japan
| | - Claes B Wollheim
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Shinichi Oikawa
- Department of Endocrinology, Diabetes and Metabolism, Graduate School of Medicine, Nippon Medical School, Tokyo, Japan
| | - Lena Eliasson
- Department of Clinical Sciences, Malmö, Islet Cell Exocytosis, Lund University Diabetes Centre, Lund University, Clinical Research Centre, Malmö, Sweden
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10
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Toubal S, Oiry C, Bayle M, Cros G, Neasta J. Urolithin C increases glucose-induced ERK activation which contributes to insulin secretion. Fundam Clin Pharmacol 2020; 34:571-580. [PMID: 32083757 DOI: 10.1111/fcp.12551] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 02/14/2020] [Accepted: 02/20/2020] [Indexed: 12/31/2022]
Abstract
Polyphenols exert pharmacological actions through protein-mediated mechanisms and by modulating intracellular signalling pathways. We recently showed that a gut-microbial metabolite of ellagic acid named urolithin C is a glucose-dependent activator of insulin secretion acting by facilitating L-type Ca2+ channel opening and Ca2+ influx into pancreatic β-cells. However, it is still unknown whether urolithin C regulates key intracellular signalling proteins in β-cells. Here, we report that urolithin C enhanced glucose-induced extracellular signal-regulated kinases 1/2 (ERK1/2) activation as shown by higher phosphorylation levels in INS-1 β-cells. Interestingly, inhibition of ERK1/2 with two structurally distinct inhibitors led to a reduction in urolithin C effect on insulin secretion. Finally, we provide data to suggest that urolithin C-mediated ERK1/2 phosphorylation involved insulin signalling in INS-1 cells. Together, these data indicate that the pharmacological action of urolithin C on insulin secretion relies, in part, on its capacity to enhance glucose-induced ERK1/2 activation. Therefore, our study extends our understanding of the pharmacological action of urolithin C in β-cells. More generally, our findings revealed that urolithin C modulated the activation of key multifunctional intracellular signalling kinases which participate in the regulation of numerous biological processes.
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Affiliation(s)
- Slimane Toubal
- IBMM, Université de Montpellier, CNRS, ENSCM, Montpellier, France
| | - Catherine Oiry
- IBMM, Université de Montpellier, CNRS, ENSCM, Montpellier, France
| | - Morgane Bayle
- IBMM, Université de Montpellier, CNRS, ENSCM, Montpellier, France
| | - Gérard Cros
- IBMM, Université de Montpellier, CNRS, ENSCM, Montpellier, France
| | - Jérémie Neasta
- IBMM, Université de Montpellier, CNRS, ENSCM, Montpellier, France
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11
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Marafie SK, Al-Shawaf EM, Abubaker J, Arefanian H. Palmitic acid-induced lipotoxicity promotes a novel interplay between Akt-mTOR, IRS-1, and FFAR1 signaling in pancreatic β-cells. Biol Res 2019; 52:44. [PMID: 31426858 PMCID: PMC6699284 DOI: 10.1186/s40659-019-0253-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 08/12/2019] [Indexed: 01/05/2023] Open
Abstract
Background Free fatty acid receptor 1 (FFAR1) is G-protein coupled receptor predominantly expressed in pancreatic β-cells that is activated by a variety of free fatty acids (FFAs). Once activated, it promotes glucose-stimulated insulin secretion (GSIS). However, increased levels of FFAs lead to lipotoxicity, inducing loss of β-cell function. FFAR1 plays a key role in the development of type 2 diabetes (T2D), and previous studies have indicated the importance of developing anti-diabetic therapies against FFAR1, although its role in the regulation of β-cell function remains unclear. The present study investigated the role of FFAR1 under lipotoxic conditions using palmitic acid (PA). The rat insulinoma 1 clone 832/13 (INS-1 832/13) cell line was used as a model as it physiologically resembles native pancreatic β-cells. Key players of the insulin signaling pathway, such as mTOR, Akt, IRS-1, and the insulin receptor (INSR1β), were selected as candidates to be analyzed under lipotoxic conditions. Results We revealed that PA-induced lipotoxicity affected GSIS in INS-1 cells and negatively modulated the activity of both IRS-1 and Akt. Reduced phosphorylation of both IRS-1 S636/639 and Akt S473 was observed, in addition to decreased expression of both INSR1β and FFAR1. Moreover, transient knockdown of FFAR1 led to a reduction in IRS-1 mRNA expression and an increase in INSR1β mRNA. Finally, PA affected localization of FFAR1 from the cytoplasm to the perinucleus. Conclusions In conclusion, our study suggests a novel regulatory involvement of FFAR1 in crosstalk with mTOR–Akt and IRS-1 signaling in β-cells under lipotoxic conditions.
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Affiliation(s)
- Sulaiman K Marafie
- Biochemistry & Molecular Biology Department, Dasman Diabetes Institute, P. O. Box 1180, 15462, Dasman, Kuwait.
| | - Eman M Al-Shawaf
- Biochemistry & Molecular Biology Department, Dasman Diabetes Institute, P. O. Box 1180, 15462, Dasman, Kuwait
| | - Jehad Abubaker
- Biochemistry & Molecular Biology Department, Dasman Diabetes Institute, P. O. Box 1180, 15462, Dasman, Kuwait
| | - Hossein Arefanian
- Microbiology & Immunology Department, Dasman Diabetes Institute, P. O. Box 1180, 15462, Dasman, Kuwait.
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12
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Najjar SM, Perdomo G. Hepatic Insulin Clearance: Mechanism and Physiology. Physiology (Bethesda) 2019; 34:198-215. [PMID: 30968756 DOI: 10.1152/physiol.00048.2018] [Citation(s) in RCA: 120] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Upon its secretion from pancreatic β-cells, insulin reaches the liver through the portal circulation to exert its action and eventually undergo clearance in the hepatocytes. In addition to insulin secretion, hepatic insulin clearance regulates the homeostatic level of insulin that is required to reach peripheral insulin target tissues to elicit proper insulin action. Receptor-mediated insulin uptake followed by its degradation constitutes the basic mechanism of insulin clearance. Upon its phosphorylation by the insulin receptor tyrosine kinase, carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) takes part in the insulin-insulin receptor complex to increase the rate of its endocytosis and targeting to the degradation pathways. This review summarizes how this process is regulated and how it is associated with insulin-degrading enzyme in the liver. It also discusses the physiological implications of impaired hepatic insulin clearance: Whereas reduced insulin clearance cooperates with increased insulin secretion to compensate for insulin resistance, it can also cause hepatic insulin resistance. Because chronic hyperinsulinemia stimulates hepatic de novo lipogenesis, impaired insulin clearance also causes hepatic steatosis. Thus impaired insulin clearance can underlie the link between hepatic insulin resistance and hepatic steatosis. Delineating these regulatory pathways should lead to building more effective therapeutic strategies against metabolic syndrome.
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Affiliation(s)
- Sonia M Najjar
- Department of Biomedical Sciences, Ohio University , Athens, Ohio.,Diabetes Institute, Heritage College of Osteopathic Medicine, Ohio University , Athens, Ohio
| | - Germán Perdomo
- Departamento de Ciencias de la Salud, Universidad de Burgos , Burgos , Spain
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13
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Paschen M, Moede T, Valladolid-Acebes I, Leibiger B, Moruzzi N, Jacob S, García-Prieto CF, Brismar K, Leibiger IB, Berggren PO. Diet-induced β-cell insulin resistance results in reversible loss of functional β-cell mass. FASEB J 2018; 33:204-218. [PMID: 29957055 PMCID: PMC6355083 DOI: 10.1096/fj.201800826r] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Although convincing in genetic models, the relevance of β-cell insulin resistance in diet-induced type 2 diabetes (T2DM) remains unclear. Exemplified by diabetes-prone, male, C57B1/6J mice being fed different combinations of Western-style diet, we show that β-cell insulin resistance occurs early during T2DM progression and is due to a combination of lipotoxicity and increased β-cell workload. Within 8 wk of being fed a high-fat, high-sucrose diet, mice became obese, developed impaired insulin and glucose tolerances, and displayed noncompensatory insulin release, due, at least in part, to reduced expression of syntaxin-1A. Through reporter islets transplanted to the anterior chamber of the eye, we demonstrated a concomitant loss of functional β-cell mass. When mice were changed from diabetogenic diet to normal chow diet, the diabetes phenotype was reversed, suggesting a remarkable plasticity of functional β-cell mass in the early phase of T2DM development. Our data reinforce the relevance of diet composition as an environmental factor determining different routes of diabetes progression in a given genetic background. Employing the in vivo reporter islet–monitoring approach will allow researchers to define key times in the dynamics of reversible loss of functional β-cell mass and, thus, to investigate the underlying, molecular mechanisms involved in the progression toward T2DM manifestation.—Paschen, M., Moede, T., Valladolid-Acebes, I., Leibiger, B., Moruzzi, N., Jacob, S., García-Prieto, C. F., Brismar, K., Leibiger, I. B., Berggren, P.-O. Diet-induced β-cell insulin resistance results in reversible loss of functional β-cell mass.
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Affiliation(s)
- Meike Paschen
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Tilo Moede
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Ismael Valladolid-Acebes
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Barbara Leibiger
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Noah Moruzzi
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Stefan Jacob
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Concha F García-Prieto
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Kerstin Brismar
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Ingo B Leibiger
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Per-Olof Berggren
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
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14
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Palmitate and insulin counteract glucose-induced thioredoxin interacting protein (TXNIP) expression in insulin secreting cells via distinct mechanisms. PLoS One 2018; 13:e0198016. [PMID: 29813102 PMCID: PMC5973613 DOI: 10.1371/journal.pone.0198016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Accepted: 05/12/2018] [Indexed: 01/20/2023] Open
Abstract
Glucose and palmitate synergistically stimulate insulin secretion, but chronically elevated they induce apoptotic β-cell death. The glucotoxic effect has been attributed, at least partly, to the upregulation of the oxidative stress marker thioredoxin interacting protein (TXNIP). Palmitate downregulates TXNIP expression, the functional significance of which is still under debate. This study examines the mechanism and consequence of palmitate-mediated TXNIP regulation in insulin secreting cells. Palmitate (600 μM) reduced TXNIP mRNA levels in isolated human and mouse islets independently of FFAR1/GPR40. Similar effects of palmitate were observed in INS-1E cells and mimicked by other long chain fatty acids. The lowering of TXNIP mRNA was significant already 1 h after addition of palmitate, persisted for 24 h and was directly translated to changes in TXNIP protein. The pharmacological inhibition of palmitate-induced phosphorylation of AMPK, ERK1/2, JNK and PKCα/β by BML-275, PD98059, SP600125 and Gö6976, respectively, did not abolish palmitate-mediated TXNIP downregulation. The effect of palmitate was superimposed by a time-dependent (8 h and 24 h) decline of TXNIP mRNA and protein. This decline correlated with accumulation of secreted insulin into the medium. Accordingly, exogenously added insulin reduced TXNIP mRNA and protein levels, an effect counteracted by the insulin/IGF-1 receptor antagonist linsitinib. The inhibition of PI3K and Akt/PKB increased TXNIP mRNA levels. The histone deacetylase (HDAC1/2/3) inhibitor MS-275 completely abrogated the time-dependent, insulin-mediated reduction of TXNIP, leaving the effect of palmitate unaltered. Acute stimulation of insulin secretion and chronic accentuation of cell death by palmitate occurred independently of TXNIP regulation. On the contrary, palmitate antagonized glucose-augmented ROS production. In conclusion, glucose-induced TXNIP expression is efficiently antagonized by two independent mechanisms, namely via an autocrine activation of insulin/IGF-1 receptors involving HDAC and by palmitate attenuating oxidative stress of β-cells.
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15
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Torii S, Kubota C, Saito N, Kawano A, Hou N, Kobayashi M, Torii R, Hosaka M, Kitamura T, Takeuchi T, Gomi H. The pseudophosphatase phogrin enables glucose-stimulated insulin signaling in pancreatic β cells. J Biol Chem 2018; 293:5920-5933. [PMID: 29483197 DOI: 10.1074/jbc.ra117.000301] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 02/14/2018] [Indexed: 12/18/2022] Open
Abstract
Autocrine insulin signaling is critical for pancreatic β-cell growth and activity and is at least partially controlled by protein-tyrosine phosphatases (PTPs) that act on insulin receptors (IRs). The receptor-type PTP phogrin primarily localizes on insulin secretory granules in pancreatic β cells. We recently reported that phogrin knockdown decreases the protein levels of insulin receptor substrate 2 (IRS2), whereas high-glucose stimulation promotes formation of a phogrin-IR complex that stabilizes IRS2. However, the underlying molecular mechanisms by which phogrin affects IRS2 levels are unclear. Here, we found that relative to wildtype mice, IRS2 levels in phogrin-knockout mice islets decreased by 44%. When phogrin was silenced by shRNA in pancreatic β-cell lines, glucose-induced insulin signaling led to proteasomal degradation of IRS2 via a negative feedback mechanism. Phogrin overexpression in a murine hepatocyte cell line consistently prevented chronic insulin treatment-induced IRS2 degradation. In vitro, phogrin directly bound the IR without the assistance of other proteins and protected recombinant PTP1B from oxidation to potentiate its activity toward the IR. Furthermore, phogrin expression suppressed insulin-induced local generation of hydrogen peroxide and subsequent PTP1B oxidation, which allowed progression of IR dephosphorylation. Together, these results suggest that a transient interaction of phogrin with the IR enables glucose-stimulated autocrine insulin signaling through the regulation of PTP1B activity, which is essential for suppressing feedback-mediated IRS2 degradation in pancreatic β cells.
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Affiliation(s)
| | | | | | | | - Ni Hou
- From the Biosignal Research Center and
| | - Masaki Kobayashi
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8512, Japan
| | | | - Masahiro Hosaka
- the Department of Biotechnology, Akita Prefectural University, Akita 010-0195, Japan
| | - Tadahiro Kitamura
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8512, Japan
| | - Toshiyuki Takeuchi
- From the Biosignal Research Center and.,the Administration Office, Gunma University, Maebashi, Gunma 371-8512, Japan, and
| | - Hiroshi Gomi
- the Department of Veterinary Anatomy, College of Bioresource Sciences, Nihon University, Fujisawa, Kanagawa 252-8510, Japan
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16
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Kim SY, Lee JH, Merrins MJ, Gavrilova O, Bisteau X, Kaldis P, Satin LS, Rane SG. Loss of Cyclin-dependent Kinase 2 in the Pancreas Links Primary β-Cell Dysfunction to Progressive Depletion of β-Cell Mass and Diabetes. J Biol Chem 2017; 292:3841-3853. [PMID: 28100774 DOI: 10.1074/jbc.m116.754077] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 01/13/2017] [Indexed: 11/06/2022] Open
Abstract
The failure of pancreatic islet β-cells is a major contributor to the etiology of type 2 diabetes. β-Cell dysfunction and declining β-cell mass are two mechanisms that contribute to this failure, although it is unclear whether they are molecularly linked. Here, we show that the cell cycle regulator, cyclin-dependent kinase 2 (CDK2), couples primary β-cell dysfunction to the progressive deterioration of β-cell mass in diabetes. Mice with pancreas-specific deletion of Cdk2 are glucose-intolerant, primarily due to defects in glucose-stimulated insulin secretion. Accompanying this loss of secretion are defects in β-cell metabolism and perturbed mitochondrial structure. Persistent insulin secretion defects culminate in progressive deficits in β-cell proliferation, reduced β-cell mass, and diabetes. These outcomes may be mediated directly by the loss of CDK2, which binds to and phosphorylates the transcription factor FOXO1 in a glucose-dependent manner. Further, we identified a requirement for CDK2 in the compensatory increases in β-cell mass that occur in response to age- and diet-induced stress. Thus, CDK2 serves as an important nexus linking primary β-cell dysfunction to progressive β-cell mass deterioration in diabetes.
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Affiliation(s)
- So Yoon Kim
- From the Cell Growth and Metabolism Section, Diabetes, Endocrinology, and Obesity Branch and
| | - Ji-Hyeon Lee
- From the Cell Growth and Metabolism Section, Diabetes, Endocrinology, and Obesity Branch and
| | - Matthew J Merrins
- the Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin, Madison, Wisconsin 53705
| | - Oksana Gavrilova
- the Mouse Metabolism Core Laboratory, NIDDK, National Institutes of Health, Clinical Research Center, Bethesda, Maryland 20892
| | - Xavier Bisteau
- the Institute of Molecular and Cell Biology (IMCB), A*STAR (Agency for Science, Technology and Research), 61 Biopolis Drive, Proteos#3-09, Singapore 138673, Singapore
| | - Philipp Kaldis
- the Institute of Molecular and Cell Biology (IMCB), A*STAR (Agency for Science, Technology and Research), 61 Biopolis Drive, Proteos#3-09, Singapore 138673, Singapore.,the Department of Biochemistry, National University of Singapore, Singapore 117597, Singapore, and
| | - Leslie S Satin
- the Department of Pharmacology and Brehm Center for Diabetes Research, University of Michigan Medical School, Ann Arbor, Michigan 48105
| | - Sushil G Rane
- From the Cell Growth and Metabolism Section, Diabetes, Endocrinology, and Obesity Branch and
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17
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Mizgier ML, Cataldo LR, Gutierrez J, Santos JL, Casas M, Llanos P, Contreras-Ferrat AE, Moro C, Bouzakri K, Galgani JE. Effect of Human Myotubes-Derived Media on Glucose-Stimulated Insulin Secretion. J Diabetes Res 2017; 2017:1328573. [PMID: 28286777 PMCID: PMC5329672 DOI: 10.1155/2017/1328573] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2016] [Revised: 01/01/2017] [Accepted: 01/17/2017] [Indexed: 12/11/2022] Open
Abstract
Fasting to postprandial transition requires a tight adjustment of insulin secretion to its demand, so tissue (e.g., skeletal muscle) glucose supply is assured while hypo-/hyperglycemia are prevented. High muscle glucose disposal after meals is pivotal for adapting to increased glycemia and might drive insulin secretion through muscle-released factors (e.g., myokines). We hypothesized that insulin influences myokine secretion and then increases glucose-stimulated insulin secretion (GSIS). In conditioned media from human myotubes incubated with/without insulin (100 nmol/L) for 24 h, myokines were qualitatively and quantitatively characterized using an antibody-based array and ELISA-based technology, respectively. C57BL6/J mice islets and Wistar rat beta cells were incubated for 24 h with control and conditioned media from noninsulin- and insulin-treated myotubes prior to GSIS determination. Conditioned media from insulin-treated versus nontreated myotubes had higher RANTES but lower IL6, IL8, and MCP1 concentration. Qualitative analyses revealed that conditioned media from noninsulin- and insulin-treated myotubes expressed 32 and 23 out of 80 myokines, respectively. Islets incubated with conditioned media from noninsulin-treated myotubes had higher GSIS versus control islets (p < 0.05). Meanwhile, conditioned media from insulin-treated myotubes did not influence GSIS. In beta cells, GSIS was similar across conditions. In conclusion, factors being present in noninsulin-stimulated muscle cell-derived media appear to influence GSIS in mice islets.
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Affiliation(s)
- Maria L. Mizgier
- Departamento de Nutrición, Diabetes y Metabolismo, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Luis R. Cataldo
- Departamento de Nutrición, Diabetes y Metabolismo, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Juan Gutierrez
- Departamento de Nutrición, Diabetes y Metabolismo, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - José L. Santos
- Departamento de Nutrición, Diabetes y Metabolismo, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Mariana Casas
- Centro de Estudios Moleculares de la Célula, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Paola Llanos
- Centro de Estudios Moleculares de la Célula, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
- Institute for Research in Dental Sciences, Facultad de Odontología, Universidad de Chile, Santiago, Chile
| | - Ariel E. Contreras-Ferrat
- Exercise Science Laboratory, School of Kinesiology, Faculty of Medicine, Universidad Finis Terrae, Santiago, Chile
| | - Cedric Moro
- INSERM UMR1048, Institut des Maladies Métaboliques et Cardiovasculaires, Université Paul Sabatier, Toulouse, France
| | - Karim Bouzakri
- Departement de Génétique et Développement, CMU, Université de Genève, Genève, Switzerland
- UMR DIATHEC, EA 7294, Centre Européen d'Etude du Diabète, Université de Strasbourg, Strasbourg, France
| | - Jose E. Galgani
- Departamento de Nutrición, Diabetes y Metabolismo, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
- UDA-Ciencias de la Salud, Carrera de Nutrición y Dietética, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
- *Jose E. Galgani:
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18
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Mezza T, Shirakawa J, Martinez R, Hu J, Giaccari A, Kulkarni RN. Nuclear Export of FoxO1 Is Associated with ERK Signaling in β-Cells Lacking Insulin Receptors. J Biol Chem 2016; 291:21485-21495. [PMID: 27535223 DOI: 10.1074/jbc.m116.735738] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 08/06/2016] [Indexed: 12/17/2022] Open
Abstract
The insulin/insulin-like growth factor (IGF) signaling pathway plays a critical role in the regulation of islet cell biology. However, the signaling pathway(s) utilized by insulin to directly modulate β-cells is unclear. To interrogate whether insulin exerts endocrine effects in regulating proteins in the insulin/IGF-1 signaling cascade in vivo in physiological states via the insulin receptor, we designed two experimental approaches: 1) glucose gavage and 2) hyperinsulinemic intravenous infusion, for studies in either β-cell specific insulin receptor knock-out (βIRKO) or control mice. Immunostaining of sections of pancreas (collected immediately after glucose gavage or insulin infusion) from controls showed significant increases in pAKT+, p-p70S6K+, and pERK+ β-cells and a significant decrease in % nuclear FoxO1+ β-cells compared with corresponding vehicle-treated groups. In contrast, in βIRKOs, we observed no significant changes in pAKT+ or p-p70S6K+ β-cells in either experiment; however, pERK+ β-cells were significantly increased, and an attenuated decrease in % nuclear FoxO1+ β cells was evident in response to glucose gavage or insulin infusion. Treatment of control and βIRKO β-cell lines with glucose or insulin showed significantly decreased % nuclear FoxO1+ β-cells suggesting direct effects. Furthermore, blocking MAPK signaling had virtually no effect on FoxO1 nuclear export in controls, in contrast to attenuated export in βIRKO β-cells. These data suggest insulin acts on β-cells in an endocrine manner in the normal situation; and that in β-cells lacking insulin receptors, insulin and glucose minimally activate the Akt pathway, while ERK phosphorylation and FoxO1 nuclear export occur independently of insulin signaling.
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Affiliation(s)
- Teresa Mezza
- From the Islet Cell and Regenerative Biology, Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Stem Cell Institute, Harvard Medical School, Boston, Massachusetts 02215 and.,Center for Endocrine and Metabolic Diseases, Policlinico Gemelli, Università Cattolica del Sacro Cuore, 00168 Rome, Italy
| | - Jun Shirakawa
- From the Islet Cell and Regenerative Biology, Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Stem Cell Institute, Harvard Medical School, Boston, Massachusetts 02215 and
| | - Rachael Martinez
- From the Islet Cell and Regenerative Biology, Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Stem Cell Institute, Harvard Medical School, Boston, Massachusetts 02215 and
| | - Jiang Hu
- From the Islet Cell and Regenerative Biology, Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Stem Cell Institute, Harvard Medical School, Boston, Massachusetts 02215 and
| | - Andrea Giaccari
- Center for Endocrine and Metabolic Diseases, Policlinico Gemelli, Università Cattolica del Sacro Cuore, 00168 Rome, Italy
| | - Rohit N Kulkarni
- From the Islet Cell and Regenerative Biology, Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Stem Cell Institute, Harvard Medical School, Boston, Massachusetts 02215 and
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Mezza T, Sorice GP, Conte C, Sun VA, Cefalo CMA, Moffa S, Pontecorvi A, Mari A, Kulkarni RN, Giaccari A. β-Cell Glucose Sensitivity Is Linked to Insulin/Glucagon Bihormonal Cells in Nondiabetic Humans. J Clin Endocrinol Metab 2016; 101:470-5. [PMID: 26649619 PMCID: PMC4880124 DOI: 10.1210/jc.2015-2802] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 11/30/2015] [Indexed: 11/19/2022]
Abstract
CONTEXT Insulin resistance impacts virtually all tissues, including pancreatic β cells. Individuals with insulin resistance, but without diabetes, exhibit an increased islet size because of an elevated number of both β and α cells. Neogenesis from duct cells and transdifferentiation of α cells have been postulated to contribute to the β-cell compensatory response to insulin resistance. OBJECTIVE Our objective was to explore parameters that could potentially predict altered islet morphology. METHODS We investigated 16 nondiabetic subjects by a 2-hour hyperglycemic clamp to evaluate β-cell secretory function. We analyzed pancreas samples obtained during pancreatoduodenectomy in the same patients to examine glucagon and insulin double+ cells to assess islet morphology. RESULTS Among all the functional in vivo parameters of insulin secretion that were explored (basal, first phase and total secretion, glucose sensitivity, arginine-stimulated insulin secretion), β-cell glucose sensitivity was unique in exhibiting a significant correlation with both islet size and α-β double+ islet cells. CONCLUSIONS Our data suggest that poor β-cell glucose sensitivity is linked to islet transdifferentiation, possibly from α cells to β cells, in an attempt to cope with higher demands for insulin secretion. Understanding the mechanism(s) that underlies the adaptive response of the islet cells to insulin resistance is a potential approach to design tools to enhance functional β-cell mass for diabetes therapy.
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Affiliation(s)
- Teresa Mezza
- Endo-Metabolic Diseases Unit (T.M., G.P.S., C.C., V.A.S., C.M.A.C., S.M., A.P., A. G.), Università Cattolica del Sacro Cuore, Rome, Italy; Islet Cell & Regenerative Biology (T.M., R.H.K.), Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02215; Institute of Neuroscience (A.M.), National Research Council, Padua, Italy
| | - Gian P Sorice
- Endo-Metabolic Diseases Unit (T.M., G.P.S., C.C., V.A.S., C.M.A.C., S.M., A.P., A. G.), Università Cattolica del Sacro Cuore, Rome, Italy; Islet Cell & Regenerative Biology (T.M., R.H.K.), Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02215; Institute of Neuroscience (A.M.), National Research Council, Padua, Italy
| | - Caterina Conte
- Endo-Metabolic Diseases Unit (T.M., G.P.S., C.C., V.A.S., C.M.A.C., S.M., A.P., A. G.), Università Cattolica del Sacro Cuore, Rome, Italy; Islet Cell & Regenerative Biology (T.M., R.H.K.), Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02215; Institute of Neuroscience (A.M.), National Research Council, Padua, Italy
| | - Vinsin A Sun
- Endo-Metabolic Diseases Unit (T.M., G.P.S., C.C., V.A.S., C.M.A.C., S.M., A.P., A. G.), Università Cattolica del Sacro Cuore, Rome, Italy; Islet Cell & Regenerative Biology (T.M., R.H.K.), Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02215; Institute of Neuroscience (A.M.), National Research Council, Padua, Italy
| | - Chiara M A Cefalo
- Endo-Metabolic Diseases Unit (T.M., G.P.S., C.C., V.A.S., C.M.A.C., S.M., A.P., A. G.), Università Cattolica del Sacro Cuore, Rome, Italy; Islet Cell & Regenerative Biology (T.M., R.H.K.), Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02215; Institute of Neuroscience (A.M.), National Research Council, Padua, Italy
| | - Simona Moffa
- Endo-Metabolic Diseases Unit (T.M., G.P.S., C.C., V.A.S., C.M.A.C., S.M., A.P., A. G.), Università Cattolica del Sacro Cuore, Rome, Italy; Islet Cell & Regenerative Biology (T.M., R.H.K.), Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02215; Institute of Neuroscience (A.M.), National Research Council, Padua, Italy
| | - Alfredo Pontecorvi
- Endo-Metabolic Diseases Unit (T.M., G.P.S., C.C., V.A.S., C.M.A.C., S.M., A.P., A. G.), Università Cattolica del Sacro Cuore, Rome, Italy; Islet Cell & Regenerative Biology (T.M., R.H.K.), Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02215; Institute of Neuroscience (A.M.), National Research Council, Padua, Italy
| | - Andrea Mari
- Endo-Metabolic Diseases Unit (T.M., G.P.S., C.C., V.A.S., C.M.A.C., S.M., A.P., A. G.), Università Cattolica del Sacro Cuore, Rome, Italy; Islet Cell & Regenerative Biology (T.M., R.H.K.), Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02215; Institute of Neuroscience (A.M.), National Research Council, Padua, Italy
| | - Rohit N Kulkarni
- Endo-Metabolic Diseases Unit (T.M., G.P.S., C.C., V.A.S., C.M.A.C., S.M., A.P., A. G.), Università Cattolica del Sacro Cuore, Rome, Italy; Islet Cell & Regenerative Biology (T.M., R.H.K.), Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02215; Institute of Neuroscience (A.M.), National Research Council, Padua, Italy
| | - Andrea Giaccari
- Endo-Metabolic Diseases Unit (T.M., G.P.S., C.C., V.A.S., C.M.A.C., S.M., A.P., A. G.), Università Cattolica del Sacro Cuore, Rome, Italy; Islet Cell & Regenerative Biology (T.M., R.H.K.), Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02215; Institute of Neuroscience (A.M.), National Research Council, Padua, Italy
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20
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Bedinger DH, Adams SH. Metabolic, anabolic, and mitogenic insulin responses: A tissue-specific perspective for insulin receptor activators. Mol Cell Endocrinol 2015; 415:143-56. [PMID: 26277398 DOI: 10.1016/j.mce.2015.08.013] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 08/05/2015] [Accepted: 08/09/2015] [Indexed: 12/17/2022]
Abstract
Insulin acts as the major regulator of the fasting-to-fed metabolic transition by altering substrate metabolism, promoting energy storage, and helping activate protein synthesis. In addition to its glucoregulatory and other metabolic properties, insulin can also act as a growth factor. The metabolic and mitogenic responses to insulin are regulated by divergent post-receptor signaling mechanisms downstream from the activated insulin receptor (IR). However, the anabolic and growth-promoting properties of insulin require tissue-specific inter-relationships between the two pathways, and the nature and scope of insulin-regulated processes vary greatly across tissues. Understanding the nuances of this interplay between metabolic and growth-regulating properties of insulin would have important implications for development of novel insulin and IR modulator therapies that stimulate insulin receptor activation in both pathway- and tissue-specific manners. This review will provide a unique perspective focusing on the roles of "metabolic" and "mitogenic" actions of insulin signaling in various tissues, and how these networks should be considered when evaluating selective pharmacologic approaches to prevent or treat metabolic disease.
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Affiliation(s)
| | - Sean H Adams
- Arkansas Children's Nutrition Center and University of Arkansas for Medical Sciences, Department of Pediatrics, Little Rock, AR, USA
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21
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Kapodistria K, Tsilibary EP, Politis P, Moustardas P, Charonis A, Kitsiou P. Nephrin, a transmembrane protein, is involved in pancreatic beta-cell survival signaling. Mol Cell Endocrinol 2015; 400:112-28. [PMID: 25448064 DOI: 10.1016/j.mce.2014.11.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 10/15/2014] [Accepted: 11/03/2014] [Indexed: 01/15/2023]
Abstract
Nephrin, a cell surface signaling receptor, regulates podocyte function in health and disease. We study the role of nephrin in β-cell survival signaling. We report that in mouse islet β-cells and the mouse pancreatic beta-cell line (βTC-6 cells) nephrin is associated and partly co-localized with PI3-kinase. Incubation of cells with functional anti-nephrin antibodies induced nephrin clustering at the plasma membrane, nephrin phosphorylation and recruitment of PI3-kinase to nephrin thus resulting in increased PI3K-dependent Akt phosphorylation and augmented phosphorylation/inhibition of pro-apoptotic Bad and FoxO. Nephrin silencing abolished Akt activation and increased susceptibility of cells to apoptosis. High glucose impaired nephrin signaling, increased nephrin internalization and up-regulated PKCα expression. Interestingly, a marked decrease in nephrin expression and phosphorylated Akt was observed in pancreatic islets of db/db lepr-/- diabetic mice. Our findings revealed that nephrin is involved in β-cell survival and suggest that glucose-induced changes in nephrin signaling may contribute to gradual pancreatic β-cell loss in type 2 diabetes.
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Affiliation(s)
- Katerina Kapodistria
- Institute of Biosciences and Applications, National Centre for Scientific Research, N.C.S.R. "Demokritos", Terma Patriarchou Grigoriou & Neapoleos, 15310 Agia Paraskevi, Attiki, Greece
| | - Effie-Photini Tsilibary
- Institute of Biosciences and Applications, National Centre for Scientific Research, N.C.S.R. "Demokritos", Terma Patriarchou Grigoriou & Neapoleos, 15310 Agia Paraskevi, Attiki, Greece
| | - Panagiotis Politis
- Center for Basic Research, Biomedical Research Foundation Academy of Athens (BRFAA), 4 Soranou Ephessiou, Athens 115 27, Greece
| | - Petros Moustardas
- Center for Clinical, Experimental Surgery and Translational Research, Biomedical Research Foundation Academy of Athens (BRFAA), 4 Soranou Ephessiou, Athens 115 27, Greece
| | - Aristidis Charonis
- Center for Clinical, Experimental Surgery and Translational Research, Biomedical Research Foundation Academy of Athens (BRFAA), 4 Soranou Ephessiou, Athens 115 27, Greece
| | - Paraskevi Kitsiou
- Institute of Biosciences and Applications, National Centre for Scientific Research, N.C.S.R. "Demokritos", Terma Patriarchou Grigoriou & Neapoleos, 15310 Agia Paraskevi, Attiki, Greece.
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De Jesus DF, Kulkarni RN. Epigenetic modifiers of islet function and mass. Trends Endocrinol Metab 2014; 25:628-36. [PMID: 25246382 DOI: 10.1016/j.tem.2014.08.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 08/22/2014] [Accepted: 08/25/2014] [Indexed: 01/28/2023]
Abstract
Type 2 diabetes (T2D) is associated with insulin resistance in target tissues including the β-cell, leading to significant β-cell loss and secretory dysfunction. T2D is also associated with aging, and the underlying mechanisms that increase susceptibility of an individual to develop the disease implicate epigenetics: interactions between susceptible loci and the environment. In this review, we discuss the effects of aging on β-cell function and adaptation, besides the significance of mitochondria in islet bioenergetics and epigenome. We highlight three important modulators of the islet epigenome, namely: metabolites, hormones, and the nutritional state. Unraveling the signaling pathways that regulate the islet epigenome during aging will help to better understand the development of disease progression and to design novel therapies for diabetes prevention.
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Affiliation(s)
- Dario F De Jesus
- Section of Islet Cell and Regenerative Biology, Joslin Diabetes Center, Harvard Medical School, Boston, MA 02215, USA; Graduate Program in Areas of Basic and Applied Biology (GABBA), Abdel Salazar Biomedical Sciences Institute, University of Porto, 5000 Porto, Portugal
| | - Rohit N Kulkarni
- Section of Islet Cell and Regenerative Biology, Joslin Diabetes Center, Harvard Medical School, Boston, MA 02215, USA; Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02215, USA.
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23
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Imatinib mesylate stimulates low-density lipoprotein receptor-related protein 1-mediated ERK phosphorylation in insulin-producing cells. Clin Sci (Lond) 2014; 128:17-28. [DOI: 10.1042/cs20130560] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The PDGF receptor and c-Abl inhibitor imatinib has previously been reported to counteract β-cell death and diabetes. Our findings show that imatinib might promote β-cell survival by enhancing basal LRP1 activity.
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Xu X, Wang G, Zhou T, Chen L, Chen J, Shen X. Novel approaches to drug discovery for the treatment of type 2 diabetes. Expert Opin Drug Discov 2014; 9:1047-58. [PMID: 25054271 DOI: 10.1517/17460441.2014.941352] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
INTRODUCTION Type 2 diabetes mellitus (T2DM) is a chronic, complex and multifactorial metabolic disorder, which has become a serious global health problem. The side effects of known drugs and the deficiency of long-term safety data, in addition to the already determined adverse effects for the current preclinical drugs against T2DM, have largely called upon the urgent exploration of novel therapeutic and preventative strategies against this disease. AREAS COVERED The authors highlight the potential approaches for anti-T2DM drug discovery by focusing on: the restoration of pancreatic β-cell mass, the promotion of insulin secretion, the regulation of oxidative stress and endoplasmic reticulum (ER) stress and the modulation of autophagy. EXPERT OPINION T2DM is based on the gradual development of insulin resistance and β-cell dysfunction. Thus, the restoration of β-cell function is considered as one of the promising therapeutic strategies against T2DM. The stress factors, such as oxidative stress, ER stress and autophagy, play potent roles in the regulation of β-cell apoptosis, insulin secretion and sensitivity in the development of T2DM involving complicated cross-talks. Based on multiplex stress-involved regulatory networks, more and more novel potential targets have been discovered and the multi-targeted drug leads are expected to help develop more effective clinical agents for the treatment of T2DM.
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Affiliation(s)
- Xing Xu
- Shanghai Institute of Materia Medica, Key Laboratory of Receptor Research, Chinese Academy of Sciences , 555 Zuchongzhi Road, Shanghai 201203 , China ; ;
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25
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Shirakawa J, Okuyama T, Yoshida E, Shimizu M, Horigome Y, Tuno T, Hayasaka M, Abe S, Fuse M, Togashi Y, Terauchi Y. Effects of the antitumor drug OSI-906, a dual inhibitor of IGF-1 receptor and insulin receptor, on the glycemic control, β-cell functions, and β-cell proliferation in male mice. Endocrinology 2014; 155:2102-11. [PMID: 24712877 DOI: 10.1210/en.2013-2032] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The IGF-1 receptor has become a therapeutic target for the treatment of cancer. The efficacy of OSI-906 (linstinib), a dual inhibitor of IGF-1 receptor and insulin receptor, for solid cancers has been examined in clinical trials. The effects of OSI-906, however, on the blood glucose levels and pancreatic β-cell functions have not yet been reported. We investigated the impact of OSI-906 on glycemic control, insulin secretion, β-cell mass, and β-cell proliferation in male mice. Oral administration of OSI-906 worsened glucose tolerance in a dose-dependent manner in the wild-type mice. OSI-906 at a dose equivalent to the clinical daily dose (7.5 mg/kg) transiently evoked glucose intolerance and hyperinsulinemia. Insulin receptor substrate (IRS)-2-deficient mice and mice with diet-induced obesity, both models of peripheral insulin resistance, exhibited more severe glucose intolerance after OSI-906 administration than glucokinase-haploinsufficient mice, a model of impaired insulin secretion. Phloridzin improved the hyperglycemia induced by OSI-906 in mice. In vitro, OSI-906 showed no effect on insulin secretion from isolated islets. After daily administration of OSI-906 for a week to mice, the β-cell mass and β-cell proliferation rate were significantly increased. The insulin signals in the β-cells were apparently unaffected in those mice. Taken together, the results suggest that OSI-906 could exacerbate diabetes, especially in patients with insulin resistance. On the other hand, the results suggest that the β-cell mass may expand in response to chemotherapy with this drug.
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Affiliation(s)
- Jun Shirakawa
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama-City University, Yokohama 236-0004, Japan
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Thabit H, Kumareswaran K, Haidar A, Leelarathna L, Caldwell K, Elleri D, Allen JM, Nodale M, Wilinska ME, Jackson NC, Umpleby AM, Evans ML, Hovorka R. Glucose turnover after replacement of usual therapy by insulin in insulin-naive type 2 diabetes subjects. J Clin Endocrinol Metab 2014; 99:2225-32. [PMID: 24606105 DOI: 10.1210/jc.2013-4519] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
CONTEXT Discontinuation of anti-hyperglycemic oral agents and initiation of insulin is recommended in certain clinical situations for inpatients with type 2 diabetes (T2D). The effects on glucose turnover when these agents are acutely withdrawn are poorly understood and may be of importance when insulin therapy is initiated. OBJECTIVE Our objective was to investigate alterations in glucose turnover after acute withdrawal of noninsulin therapy. DESIGN AND SETTING This was a randomized crossover study at a clinical research facility. PARTICIPANTS Participants included 12 insulin-naive subjects with T2D. METHODS Subjects attended two 24-hour visits. Standard therapy was discontinued and replaced by closed-loop insulin delivery during the intervention visit. Usual anti-hyperglycemic therapy was continued during the control visit. Systemic glucose appearance (Ra) and glucose disposal (Rd) were measured using a tracer dilution technique with iv [6,6-(2)H2]glucose. RESULTS Plasma glucose profiles during both visits were comparable (P = .48). Glucose Ra increased during the day (21.4 [19.5, 23.5] vs 18.6 [17.0, 21.6) μmol/kg/min, P = .019) and decreased overnight (9.7 [8.5, 11.4] vs 11.6 [10.3, 12.9] μmol/kg/min, P = .004) when the usual therapy was discontinued and replaced with insulin. Increased daytime glucose Rd (21.2 [19.4, 23.9] vs 18.8 [18.3, 21.7] μmol/kg/min, P = .002) and decreased overnight Rd (10.4 [9.1, 12.0] vs 11.8 [10.7, 13.7] μmol/kg/min, P = .005) were observed when the usual therapy was discontinued, whereas daytime peripheral insulin sensitivity was reduced (47.8 [24.8, 66.1] vs 62.5 [34.8, 75.8] nmol/kg/min per pmol/L, P = .034). CONCLUSION In T2D, acute discontinuation of anti-hyperglycemic therapy and replacement with insulin increases postprandial Ra and reduces peripheral insulin sensitivity. Insulin dose initiation may need to compensate for these alterations.
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Affiliation(s)
- H Thabit
- Metabolic Research Laboratories (H.T., K.K., L.L., K.C., D.E., J.M.A., M.N., M.E.W., M.L.E., R.H.), Wellcome Trust-Medical Research Council Institute of Metabolic Science, and Department of Paediatrics (D.E., J.M.A., M.E.W., R.H.), University of Cambridge, Cambridge CB2 0QQ, United Kingdom; Centre for Intelligent Machines (A.H.), McGill University, Montreal, Quebec H3A 0E9, Canada; and Postgraduate Medical School (N.C.J., A.M.U.), University of Surrey, Guildford GU2 7TE, United Kingdom
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Ravier MA, Leduc M, Richard J, Linck N, Varrault A, Pirot N, Roussel MM, Bockaert J, Dalle S, Bertrand G. β-Arrestin2 plays a key role in the modulation of the pancreatic beta cell mass in mice. Diabetologia 2014; 57:532-41. [PMID: 24317793 DOI: 10.1007/s00125-013-3130-7] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Accepted: 11/13/2013] [Indexed: 01/09/2023]
Abstract
AIMS/HYPOTHESIS Beta cell failure due to progressive secretory dysfunction and limited expansion of beta cell mass is a key feature of type 2 diabetes. Beta cell function and mass are controlled by glucose and hormones/neurotransmitters that activate G protein-coupled receptors or receptor tyrosine kinases. We have investigated the role of β-arrestin (ARRB)2, a scaffold protein known to modulate such receptor signalling, in the modulation of beta cell function and mass, with a specific interest in glucagon-like peptide-1 (GLP-1), muscarinic and insulin receptors. METHODS β-arrestin2-knockout mice and their wild-type littermates were fed a normal or a high-fat diet (HFD). Glucose tolerance, insulin sensitivity and insulin secretion were assessed in vivo. Beta cell mass was evaluated in pancreatic sections. Free cytosolic [Ca(2+)] and insulin secretion were determined using perifused islets. The insulin signalling pathway was evaluated by western blotting. RESULTS Arrb2-knockout mice exhibited impaired glucose tolerance and insulin secretion in vivo, but normal insulin sensitivity compared with wild type. Surprisingly, the absence of ARRB2 did not affect glucose-stimulated insulin secretion or GLP-1- and acetylcholine-mediated amplifications from perifused islets, but it decreased the islet insulin content and beta cell mass. Additionally, there was no compensatory beta cell mass expansion through proliferation in response to the HFD. Furthermore, Arrb2 deletion altered the islet insulin signalling pathway. CONCLUSIONS/INTERPRETATION ARRB2 is unlikely to be involved in the regulation of insulin secretion, but it is required for beta cell mass plasticity. Additionally, we provide new insights into the mechanisms involved in insulin signalling in beta cells.
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Affiliation(s)
- Magalie A Ravier
- CNRS, UMR-5203, Institut de Génomique Fonctionnelle, 141 Rue de la Cardonille, 34094, Montpellier, France
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Veras K, Almeida FN, Nachbar RT, de Jesus DS, Camporez JP, Carpinelli AR, Goedecke JH, de Oliveira Carvalho CR. DHEA supplementation in ovariectomized rats reduces impaired glucose-stimulated insulin secretion induced by a high-fat diet. FEBS Open Bio 2014; 4:141-6. [PMID: 24490138 PMCID: PMC3907747 DOI: 10.1016/j.fob.2014.01.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Revised: 12/28/2013] [Accepted: 01/13/2014] [Indexed: 12/16/2022] Open
Abstract
Dehydroepiandrosterone (DHEA) and the dehydroepiandrosterone sulfate (DHEA-S) are steroids produced mainly by the adrenal cortex. There is evidence from both human and animal models suggesting beneficial effects of these steroids for obesity, diabetes mellitus, hypertension, and osteoporosis, conditions associated with the post-menopausal period. Accordingly, we hypothesized that DHEA supplementation in ovariectomized (OVX) female rats fed a high-fat diet would maintain glucose-induced insulin secretion (GSIS) and pancreatic islet function. OVX resulted in a 30% enlargement of the pancreatic islets area compared to the control rats, which was accompanied by a 50% reduction in the phosphorylation of AKT protein in the pancreatic islets. However, a short-term high-fat diet induced insulin resistance, accompanied by impaired GSIS in isolated pancreatic islets. These effects were reversed by DHEA treatment, with improved insulin sensitivity to levels similar to the control group, and with increased serine phosphorylation of the AKT protein. These data confirm the protective effect of DHEA on the endocrine pancreas in a situation of diet-induced overweight and low estrogen concentrations, a phenotype similar to that of the post-menopausal period. Dehydroepiandrosterone (DHEA) is a physiological precursor of androgens and estrogens. Ovariectomized rats fed a high-fat diet showed insulin resistance and impaired glucose-induced insulin secretion. These effects were reversed by DHEA treatment, with improved insulin secretion and sensitivity.
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Key Words
- DHEA, dehydroepiandrosterone
- DHEA-S, dehydroepiandrosterone sulfate
- GSIS, glucose-induced insulin secretion
- GTT, glucose tolerance test
- HFD, high-fat diet
- High fat diet
- Insulin secretion
- Insulin sensitivity
- Kitt, glucose disappearance rate
- Menopause
- OHL, ovariectomized rats fed HFD
- OHLD, ovariectomized rats fed a HFD and treated with DHEA
- OVX, ovariectomized rats
- PI, propidium iodide
- PI3K, phosphatidylinositol-3-kinase
- PI3K-PDK1-Akt, PI3K-3-phosphoinositide dependent kinase-Akt
- Pancreatic islets
- SDS–PAGE, sodium dodecyl sulfate poly-acrylamide electrophoresis
- SHAM, sham-operated rats
- SHL, sham rats fed a HFD
- p-Akt/Akt
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Affiliation(s)
- Katherine Veras
- Department of Physiology and Biophysics, ICB 1, USP, São Paulo, SP, Brazil
| | | | | | | | | | | | - Julia H Goedecke
- South African Medical Research Council and Department of Human Biology, University of Cape Town, Cape Town, South Africa
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Abstract
In recent years there has been a growing interest in the possibility of a direct autocrine effect of insulin on the pancreatic β-cell. Indeed, there have been numerous intriguing articles and several eloquent reviews written on the subject (1-3); however, the concept is still controversial. Although many in vitro experiments, a few transgenic mouse studies, and some human investigations would be supportive of the notion, there exist different insights, other studies, and circumstantial evidence that question the concept. Therefore, the idea of autocrine action of insulin remains a conundrum. Here we outline a series of thoughts, insights, and alternative interpretations of the available experimental evidence. We ask, how convincing are these, and what are the confusing issues? We agree that there is a clear contribution of certain downstream elements in the insulin signaling pathway for β-cell function and survival, but the question of whether insulin itself is actually the physiologically relevant ligand that triggers this signal transduction remains unsettled.
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Affiliation(s)
- Christopher J Rhodes
- Kovler Diabetes Center, Department of Medicine, University of Chicago, Chicago, Illinois, USA.
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Minze MG, Klein MS, Terrell BT. Saxagliptin and Metformin in Fixed Combination for the Treatment of Type 2 Diabetes in Adults. Clin Med Insights Endocrinol Diabetes 2013; 6:15-24. [PMID: 23966808 PMCID: PMC3738378 DOI: 10.4137/cmed.s8510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Type 2 diabetes affects millions of people worldwide and significantly contributes to morbidity and mortality of those affected by it. Current guidelines recommend individualized treatment regimens following first line metformin therapy. Saxagliptin, a dipeptidyl-peptidase 4 inhibitor, provides a secondary mechanism of action to decrease hyperglycemia when used in combination with metformin. The combination of metformin and saxagliptin has shown improvements in hemoglobin A1c and fasting plasma glucose in greater efficacy than when either agent is used alone. Adverse effects of combination therapy are similar to when these agents are used individually, and are rated as tolerable by patient satisfaction scores. Overall, the combination use of saxagliptin in addition to metformin is an attractive option for clinicians to use in the treatment of type 2 diabetes.
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Affiliation(s)
- Molly G. Minze
- School of Pharmacy, Texas Tech University Health Sciences Center, Abilene, Texas
| | - Mary S. Klein
- School of Pharmacy, Texas Tech University Health Sciences Center, Abilene, Texas
| | - Brian T. Terrell
- School of Pharmacy, Texas Tech University Health Sciences Center, Abilene, Texas
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