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Stamateris RE, Landa-Galvan HV, Sharma RB, Darko C, Redmond D, Rane SG, Alonso LC. Noncanonical CDK4 signaling rescues diabetes in a mouse model by promoting β cell differentiation. J Clin Invest 2023; 133:e166490. [PMID: 37712417 PMCID: PMC10503800 DOI: 10.1172/jci166490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Accepted: 07/27/2023] [Indexed: 09/16/2023] Open
Abstract
Expanding β cell mass is a critical goal in the fight against diabetes. CDK4, an extensively characterized cell cycle activator, is required to establish and maintain β cell number. β cell failure in the IRS2-deletion mouse type 2 diabetes model is, in part, due to loss of CDK4 regulator cyclin D2. We set out to determine whether replacement of endogenous CDK4 with the inhibitor-resistant mutant CDK4-R24C rescued the loss of β cell mass in IRS2-deficient mice. Surprisingly, not only β cell mass but also β cell dedifferentiation was effectively rescued, despite no improvement in whole body insulin sensitivity. Ex vivo studies in primary islet cells revealed a mechanism in which CDK4 intervened downstream in the insulin signaling pathway to prevent FOXO1-mediated transcriptional repression of critical β cell transcription factor Pdx1. FOXO1 inhibition was not related to E2F1 activity, to FOXO1 phosphorylation, or even to FOXO1 subcellular localization, but rather was related to deacetylation and reduced FOXO1 abundance. Taken together, these results demonstrate a differentiation-promoting activity of the classical cell cycle activator CDK4 and support the concept that β cell mass can be expanded without compromising function.
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Affiliation(s)
- Rachel E. Stamateris
- MD/PhD Program, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Huguet V. Landa-Galvan
- Division of Endocrinology, Diabetes and Metabolism and the Joan and Sanford I. Weill Center for Metabolic Health and
| | - Rohit B. Sharma
- Division of Endocrinology, Diabetes and Metabolism and the Joan and Sanford I. Weill Center for Metabolic Health and
| | - Christine Darko
- Division of Endocrinology, Diabetes and Metabolism and the Joan and Sanford I. Weill Center for Metabolic Health and
| | - David Redmond
- Hartman Institute for Therapeutic Regenerative Medicine, Division of Regenerative Medicine, Department of Medicine, Weill Cornell Medicine, New York, New York, USA
| | - Sushil G. Rane
- Integrative Cellular Metabolism Section, Diabetes, Endocrinology and Obesity Branch, National Institute for Diabetes, Digestive and Kidney Diseases, NIH, Bethesda, Maryland, USA
| | - Laura C. Alonso
- Division of Endocrinology, Diabetes and Metabolism and the Joan and Sanford I. Weill Center for Metabolic Health and
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2
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Oger F, Bourouh C, Friano ME, Courty E, Rolland L, Gromada X, Moreno M, Carney C, Rabhi N, Durand E, Amanzougarene S, Berberian L, Derhourhi M, Blanc E, Hannou SA, Denechaud PD, Benfodda Z, Meffre P, Fajas L, Kerr-Conte J, Pattou F, Froguel P, Pourcet B, Bonnefond A, Collombat P, Annicotte JS. β-Cell-Specific E2f1 Deficiency Impairs Glucose Homeostasis, β-Cell Identity, and Insulin Secretion. Diabetes 2023; 72:1112-1126. [PMID: 37216637 DOI: 10.2337/db22-0604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 05/01/2023] [Indexed: 05/24/2023]
Abstract
The loss of pancreatic β-cell identity has emerged as an important feature of type 2 diabetes development, but the molecular mechanisms are still elusive. Here, we explore the cell-autonomous role of the cell-cycle regulator and transcription factor E2F1 in the maintenance of β-cell identity, insulin secretion, and glucose homeostasis. We show that the β-cell-specific loss of E2f1 function in mice triggers glucose intolerance associated with defective insulin secretion, altered endocrine cell mass, downregulation of many β-cell genes, and concomitant increase of non-β-cell markers. Mechanistically, epigenomic profiling of the promoters of these non-β-cell upregulated genes identified an enrichment of bivalent H3K4me3/H3K27me3 or H3K27me3 marks. Conversely, promoters of downregulated genes were enriched in active chromatin H3K4me3 and H3K27ac histone marks. We find that specific E2f1 transcriptional, cistromic, and epigenomic signatures are associated with these β-cell dysfunctions, with E2F1 directly regulating several β-cell genes at the chromatin level. Finally, the pharmacological inhibition of E2F transcriptional activity in human islets also impairs insulin secretion and the expression of β-cell identity genes. Our data suggest that E2F1 is critical for maintaining β-cell identity and function through sustained control of β-cell and non-β-cell transcriptional programs. ARTICLE HIGHLIGHTS β-Cell-specific E2f1 deficiency in mice impairs glucose tolerance. Loss of E2f1 function alters the ratio of α- to β-cells but does not trigger β-cell conversion into α-cells. Pharmacological inhibition of E2F activity inhibits glucose-stimulated insulin secretion and alters β- and α-cell gene expression in human islets. E2F1 maintains β-cell function and identity through control of transcriptomic and epigenetic programs.
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Affiliation(s)
- Frédérik Oger
- INSERM, U1283 - UMR8199 - European Genomic Institute for Diabetes (EGID), CNRS, Institut Pasteur de Lille, CHU Lille, Université de Lille, Lille, France
| | - Cyril Bourouh
- INSERM, U1283 - UMR8199 - European Genomic Institute for Diabetes (EGID), CNRS, Institut Pasteur de Lille, CHU Lille, Université de Lille, Lille, France
| | - Marika Elsa Friano
- INSERM, CNRS, Institut de Biologie Valrose, Université Côte d'Azur, Nice, France
| | - Emilie Courty
- INSERM, U1167 - RID-AGE - Facteurs de Risque et Déterminants Moléculaires des Maladies Liées au Vieillissement, Institut Pasteur de Lille, CHU Lille, Université de Lille, Lille, France
| | - Laure Rolland
- INSERM, U1167 - RID-AGE - Facteurs de Risque et Déterminants Moléculaires des Maladies Liées au Vieillissement, Institut Pasteur de Lille, CHU Lille, Université de Lille, Lille, France
| | - Xavier Gromada
- INSERM, U1283 - UMR8199 - European Genomic Institute for Diabetes (EGID), CNRS, Institut Pasteur de Lille, CHU Lille, Université de Lille, Lille, France
| | - Maeva Moreno
- INSERM, U1283 - UMR8199 - European Genomic Institute for Diabetes (EGID), CNRS, Institut Pasteur de Lille, CHU Lille, Université de Lille, Lille, France
| | - Charlène Carney
- INSERM, U1283 - UMR8199 - European Genomic Institute for Diabetes (EGID), CNRS, Institut Pasteur de Lille, CHU Lille, Université de Lille, Lille, France
| | - Nabil Rabhi
- Department of Biochemistry, Boston University School of Medicine, Boston, MA
| | - Emmanuelle Durand
- INSERM, U1283 - UMR8199 - European Genomic Institute for Diabetes (EGID), CNRS, Institut Pasteur de Lille, CHU Lille, Université de Lille, Lille, France
| | - Souhila Amanzougarene
- INSERM, U1283 - UMR8199 - European Genomic Institute for Diabetes (EGID), CNRS, Institut Pasteur de Lille, CHU Lille, Université de Lille, Lille, France
| | - Lionel Berberian
- INSERM, U1283 - UMR8199 - European Genomic Institute for Diabetes (EGID), CNRS, Institut Pasteur de Lille, CHU Lille, Université de Lille, Lille, France
| | - Mehdi Derhourhi
- INSERM, U1283 - UMR8199 - European Genomic Institute for Diabetes (EGID), CNRS, Institut Pasteur de Lille, CHU Lille, Université de Lille, Lille, France
| | - Etienne Blanc
- INSERM, U1283 - UMR8199 - European Genomic Institute for Diabetes (EGID), CNRS, Institut Pasteur de Lille, CHU Lille, Université de Lille, Lille, France
| | - Sarah Anissa Hannou
- INSERM, U1283 - UMR8199 - European Genomic Institute for Diabetes (EGID), CNRS, Institut Pasteur de Lille, CHU Lille, Université de Lille, Lille, France
| | | | | | | | - Lluis Fajas
- Center for Integrative Genomics, Université de Lausanne, Lausanne, Switzerland
| | - Julie Kerr-Conte
- INSERM, U1190 - EGID, Institut Pasteur de Lille, CHU Lille, Université de Lille, Lille, France
| | - François Pattou
- INSERM, U1190 - EGID, Institut Pasteur de Lille, CHU Lille, Université de Lille, Lille, France
| | - Philippe Froguel
- INSERM, U1283 - UMR8199 - European Genomic Institute for Diabetes (EGID), CNRS, Institut Pasteur de Lille, CHU Lille, Université de Lille, Lille, France
- Department of Metabolism, Hammersmith Hospital, Imperial College London, London, U.K
| | - Benoit Pourcet
- INSERM, U1011 - EGID, Institut Pasteur de Lille, CHU Lille, Université de Lille, Lille, France
| | - Amélie Bonnefond
- INSERM, U1283 - UMR8199 - European Genomic Institute for Diabetes (EGID), CNRS, Institut Pasteur de Lille, CHU Lille, Université de Lille, Lille, France
- Department of Metabolism, Hammersmith Hospital, Imperial College London, London, U.K
| | - Patrick Collombat
- INSERM, CNRS, Institut de Biologie Valrose, Université Côte d'Azur, Nice, France
| | - Jean-Sébastien Annicotte
- INSERM, U1167 - RID-AGE - Facteurs de Risque et Déterminants Moléculaires des Maladies Liées au Vieillissement, Institut Pasteur de Lille, CHU Lille, Université de Lille, Lille, France
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3
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Ahmed SM, Elshenawy SE, Sedky S, Elmehrath AO, El-Badri N. Pancreatic β-Cell Senescence: Mechanisms and Association with Diabetes. EUROPEAN MEDICAL JOURNAL 2021. [DOI: 10.33590/emj/20-00128] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Senescence occurs as a part of the cellular response to different stressors. With increasing age, continuous exposure to stressors leads to age-induced senescence. Pancreatic β-cell proliferation and glucose homeostasis also decrease with age, which results in a decrease in β cell mass and, eventually, the possible development of diabetes. This process is mediated through impaired cell cycle regulators, along with specific increases in cell cycle inhibitors, telomere shortening, and defective DNA repair mechanisms. Diabetes contributes to β-cell senescence through hyperglycaemia, dyslipidaemia, oxidative stress, and inflammation. β cells isolated from patients with Type 2 diabetes mellitus have been shown to have senescence markers, such as senescence-associated secretory phenotype genes and β-galactosidase. In this paper, the authors discuss the mechanisms of cellular senescence, how senescence is impacted by the diabetic microenvironment, and the possible mechanisms and factors contributing to β-cell senescence.
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Affiliation(s)
- Sara M Ahmed
- Center of Excellence for Stem Cells and Regenerative Medicine (CESC), Zewail City of Science and Technology, Giza, Egypt
| | - Shimaa E Elshenawy
- Center of Excellence for Stem Cells and Regenerative Medicine (CESC), Zewail City of Science and Technology, Giza, Egypt
| | - Sara Sedky
- Center of Excellence for Stem Cells and Regenerative Medicine (CESC), Zewail City of Science and Technology, Giza, Egypt
| | - Ahmed O Elmehrath
- Center of Excellence for Stem Cells and Regenerative Medicine (CESC), Zewail City of Science and Technology, Giza, Egypt; Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Nagwa El-Badri
- Center of Excellence for Stem Cells and Regenerative Medicine (CESC), Zewail City of Science and Technology, Giza, Egypt
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4
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Lopez-Mejia IC, Castillo-Armengol J, Lagarrigue S, Fajas L. Role of cell cycle regulators in adipose tissue and whole body energy homeostasis. Cell Mol Life Sci 2018; 75:975-987. [PMID: 28988292 PMCID: PMC11105252 DOI: 10.1007/s00018-017-2668-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 09/01/2017] [Accepted: 09/26/2017] [Indexed: 05/22/2024]
Abstract
In the course of the last decades, metabolism research has demonstrated that adipose tissue is not an inactive tissue. Rather, adipocytes are key actors of whole body energy homeostasis. Numerous novel regulators of adipose tissue differentiation and function have been identified. With the constant increase of obesity and associated disorders, the interest in adipose tissue function alterations in the XXIst century has become of paramount importance. Recent data suggest that adipocyte differentiation, adipose tissue browning and mitochondrial function, lipogenesis and lipolysis are strongly modulated by the cell division machinery. This review will focus on the function of cell cycle regulators in adipocyte differentiation, adipose tissue function and whole body energy homeostasis; with particular attention in mouse studies.
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Affiliation(s)
- I C Lopez-Mejia
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
- Department of Physiology, University of Lausanne, Lausanne, Switzerland
| | - J Castillo-Armengol
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
- Department of Physiology, University of Lausanne, Lausanne, Switzerland
| | - S Lagarrigue
- Department of Physiology, University of Lausanne, Lausanne, Switzerland
| | - L Fajas
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland.
- Department of Physiology, University of Lausanne, Lausanne, Switzerland.
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5
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Alonso-Magdalena P, García-Arévalo M, Quesada I, Nadal Á. Bisphenol-A treatment during pregnancy in mice: a new window of susceptibility for the development of diabetes in mothers later in life. Endocrinology 2015; 156:1659-70. [PMID: 25830705 DOI: 10.1210/en.2014-1952] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Evidence now exists supporting the hypothesis that endocrine-disrupting chemicals (EDCs) can harmfully impact glucose metabolism. Thus, EDCs are beginning to be considered important contributors to the increased incidence of diabetes, obesity, or both. The possible effect of exposure to EDCs during pregnancy on glucose homeostasis in mothers later in life is presently unknown. Here we show that several months after delivery, mothers treated with the widespread EDC bisphenol-A (BPA) during gestation, at environmentally relevant doses, exhibit profound glucose intolerance and altered insulin sensitivity as well as increased body weight. These mice presented a decreased insulin secretion both in vivo and in vitro together with reduced pancreatic β-cell mass. The proliferation capacity was decreased in association with a diminished expression of the cell cycle activators: cyclin D2 and cyclin-dependent kinase-4. In addition, the rate of β-cells apoptosis was increased as well as the expression of the cell cycle inhibitors p16 and p53. Conversely, no effects on glucose metabolism or insulin sensitivity were observed when female nonpregnant mice were treated with BPA at the same doses. Taken together, these findings reveal that BPA exposure during gestation has harmful long-term implications in glucose metabolism for the mother. This finding highlights a new window of susceptibility for EDC exposure that may be important for the development of type 2 diabetes.
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Affiliation(s)
- Paloma Alonso-Magdalena
- Departamento de Biología Aplicada (P.A.-M., I.Q.), Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM) (P.A.-M., M.G.-A., I.Q., A.N.), Universidad Miguel Hernández de Elche, Elche 03202, Alicante, Spain
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6
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Alejandro EU, Gregg B, Blandino-Rosano M, Cras-Méneur C, Bernal-Mizrachi E. Natural history of β-cell adaptation and failure in type 2 diabetes. Mol Aspects Med 2014; 42:19-41. [PMID: 25542976 DOI: 10.1016/j.mam.2014.12.002] [Citation(s) in RCA: 163] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Revised: 11/04/2014] [Accepted: 12/05/2014] [Indexed: 02/07/2023]
Abstract
Type 2 diabetes mellitus (T2D) is a complex disease characterized by β-cell failure in the setting of insulin resistance. The current evidence suggests that genetic predisposition, and environmental factors can impair the capacity of the β-cells to respond to insulin resistance and ultimately lead to their failure. However, genetic studies have demonstrated that known variants account for less than 10% of the overall estimated T2D risk, suggesting that additional unidentified factors contribute to susceptibility of this disease. In this review, we will discuss the different stages that contribute to the development of β-cell failure in T2D. We divide the natural history of this process in three major stages: susceptibility, β-cell adaptation and β-cell failure, and provide an overview of the molecular mechanisms involved. Further research into mechanisms will reveal key modulators of β-cell failure and thus identify possible novel therapeutic targets and potential interventions to protect against β-cell failure.
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Affiliation(s)
- Emilyn U Alejandro
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan, Ann Arbor, MI, USA
| | - Brigid Gregg
- Department of Pediatrics, University of Michigan, Ann Arbor, MI, USA
| | - Manuel Blandino-Rosano
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan, Ann Arbor, MI, USA
| | - Corentin Cras-Méneur
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan, Ann Arbor, MI, USA
| | - Ernesto Bernal-Mizrachi
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan, Ann Arbor, MI, USA; VA Ann Arbor Healthcare System, Ann Arbor, MI, USA.
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7
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Tavana O, Puebla-Osorio N, Kim J, Sang M, Jang S, Zhu C. Ku70 functions in addition to nonhomologous end joining in pancreatic β-cells: a connection to β-catenin regulation. Diabetes 2013; 62:2429-38. [PMID: 23474484 PMCID: PMC3712041 DOI: 10.2337/db12-1218] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The genesis of β-cells predominantly occurs through self-replication; therefore, understanding the regulation of cell proliferation is essential. We previously showed that the lack of nonhomologous end joining (NHEJ) DNA repair factor ligase IV leads to an accumulation of DNA damage that permanently halts β-cell proliferation and dramatically decreases insulin production, causing overt diabetes in a hypomorphic p53(R172P) background. In the present study, to further delineate the function of NHEJ, we analyzed mice deficient for another key NHEJ factor, Ku70, to discover the effect of cellular responses to DNA damage in pancreatic β-cells on cellular proliferation and glucose homeostasis. Analysis of Ku70(-/-) pancreatic β-cells revealed an accumulation of DNA damage and activation of p53-dependent cellular senescence similar to the results found in our earlier ligase IV deficiency study. To our surprise, Ku70(-/-) mice had significantly increased β-cell proliferation and islet expansion, heightened insulin levels, and decreased glycemia. This augmented β-cell proliferation was accompanied by an increased β-catenin level, which we propose to be responsible for this phenotype. This study highlights Ku70 as an important player not only in maintaining genomic stability through NHEJ-dependent functions, but also in regulating pancreatic β-cell proliferation, a novel NHEJ-independent function.
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Affiliation(s)
- Omid Tavana
- Department of Immunology, The University of Texas MD Anderson Cancer Center, Houston, Texas
- The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas
| | - Nahum Puebla-Osorio
- Department of Immunology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Jiseong Kim
- Department of Immunology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Mei Sang
- Department of Immunology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Stella Jang
- Department of Immunology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Chengming Zhu
- Department of Immunology, The University of Texas MD Anderson Cancer Center, Houston, Texas
- The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas
- Corresponding author: Chengming Zhu,
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8
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Kobayashi M, Kikuchi O, Sasaki T, Kim HJ, Yokota-Hashimoto H, Lee YS, Amano K, Kitazumi T, Susanti VY, Kitamura YI, Kitamura T. FoxO1 as a double-edged sword in the pancreas: analysis of pancreas- and β-cell-specific FoxO1 knockout mice. Am J Physiol Endocrinol Metab 2012; 302:E603-13. [PMID: 22215655 DOI: 10.1152/ajpendo.00469.2011] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Diabetes is characterized by an absolute or relative deficiency of pancreatic β-cells. New strategies to accelerate β-cell neogenesis or maintain existing β-cells are desired for future therapies against diabetes. We previously reported that forkhead box O1 (FoxO1) inhibits β-cell growth through a Pdx1-mediated mechanism. However, we also reported that FoxO1 protects against β-cell failure via the induction of NeuroD and MafA. Here, we investigate the physiological roles of FoxO1 in the pancreas by generating the mice with deletion of FoxO1 in the domains of the Pdx1 promoter (P-FoxO1-KO) or the insulin 2 promoter (β-FoxO1-KO) and analyzing the metabolic parameters and pancreatic morphology under two different conditions of increased metabolic demand: high-fat high-sucrose diet (HFHSD) and db/db background. P-FoxO1-KO, but not β-FoxO1-KO, showed improved glucose tolerance with HFHSD. Immunohistochemical analysis revealed that P-FoxO1-KO had increased β-cell mass due to increased islet number rather than islet size, indicating accelerated β-cell neogenesis. Furthermore, insulin-positive pancreatic duct cells were increased in P-FoxO1-KO but not β-FoxO1-KO. In contrast, db/db mice crossed with P-FoxO1-KO or β-FoxO1-KO showed more severe glucose intolerance than control db/db mice due to decreased glucose-responsive insulin secretion. Electron microscope analysis revealed fewer insulin granules in FoxO1 knockout db/db mice. We conclude that FoxO1 functions as a double-edged sword in the pancreas; FoxO1 essentially inhibits β-cell neogenesis from pancreatic duct cells but is required for the maintenance of insulin secretion under metabolic stress.
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Affiliation(s)
- Masaki Kobayashi
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma, Japan
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9
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Lagarrigue S, Blanchet É, Annicotte JS, Fajas L. Le double jeu des régulateurs du cycle cellulaire. Med Sci (Paris) 2011; 27:508-13. [DOI: 10.1051/medsci/2011275016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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10
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Sun G, Tarasov AI, McGinty JA, French PM, McDonald A, Leclerc I, Rutter GA. LKB1 deletion with the RIP2.Cre transgene modifies pancreatic beta-cell morphology and enhances insulin secretion in vivo. Am J Physiol Endocrinol Metab 2010; 298:E1261-73. [PMID: 20354156 PMCID: PMC2886523 DOI: 10.1152/ajpendo.00100.2010] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The tumor suppressor liver kinase B1 (LKB1), also called STK11, is a protein kinase mutated in Peutz-Jeghers syndrome. LKB1 phosphorylates AMP-activated protein kinase (AMPK) and several related protein kinases. Whereas deletion of both catalytic isoforms of AMPK from the pancreatic beta-cell and hypothalamic neurons using the rat insulin promoter (RIP2).Cre transgene (betaAMPKdKO) diminishes insulin secretion in vivo, deletion of LKB1 in the beta-cell with an inducible Pdx-1.CreER transgene enhances insulin secretion in mice. To determine whether the differences between these models reflect genuinely distinct roles for the two kinases in the beta-cell or simply differences in the timing and site(s) of deletion, we have therefore created mice deleted for LKB1 with the RIP2.Cre transgene. In marked contrast to betaAMPKdKO mice, betaLKB1KO mice showed diminished food intake and weight gain, enhanced insulin secretion, unchanged insulin sensitivity, and improved glucose tolerance. In line with the phenotype of Pdx1-CreER mice, total beta-cell mass and the size of individual islets and beta-cells were increased and islet architecture was markedly altered in betaLKB1KO islets. Signaling by mammalian target of rapamycin (mTOR) to eIF4-binding protein-1 and ribosomal S6 kinase was also enhanced. In contrast to Pdx1-CreER-mediated deletion, the expression of Glut2, glucose-induced changes in membrane potential and intracellular Ca(2+) were sharply reduced in betaLKB1KO mouse islets and the stimulation of insulin secretion was modestly inhibited. We conclude that LKB1 and AMPK play distinct roles in the control of insulin secretion and that the timing of LKB1 deletion, and/or its loss from extrapancreatic sites, influences the final impact on beta-cell function.
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Affiliation(s)
- Gao Sun
- Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, London, UK
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11
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Current literature in diabetes. Diabetes Metab Res Rev 2009; 25:i-xii. [PMID: 19405078 DOI: 10.1002/dmrr.973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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12
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Sachdeva MM, Stoffers DA. Minireview: Meeting the demand for insulin: molecular mechanisms of adaptive postnatal beta-cell mass expansion. Mol Endocrinol 2009; 23:747-58. [PMID: 19196831 DOI: 10.1210/me.2008-0400] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Type 2 diabetes results from pancreatic ss-cell failure in the setting of insulin resistance. This model of disease progression has received recent support from the results of genome-wide association studies that identify genes potentially regulating ss-cell growth and function as type 2 diabetes susceptibility loci. Normal ss-cell compensation for an increased insulin demand includes both enhanced insulin-secretory capacity and an expansion of morphological ss-cell mass, due largely to changes in the balance between ss-cell proliferation and apoptosis. Recent years have brought significant progress in the understanding of both extrinsic signals stimulating ss-cell growth as well as mediators intrinsic to the ss-cell that regulate the compensatory response. Here, we review the current knowledge of mechanisms underlying adaptive expansion of ss-cell mass, focusing on lessons learned from experimental models of physiologically occurring insulin-resistant states including diet-induced obesity and pregnancy, and highlighting the potential importance of interorgan cross talk. The identification of critical mediators of islet compensation may direct the development of future therapeutic strategies to enhance the response of ss-cells to insulin resistance.
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Affiliation(s)
- Mira M Sachdeva
- Department of Medicine, Institute for Diabetes, Obesity, and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, 19104, USA
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