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Zaïmia N, Obeid J, Varrault A, Sabatier J, Broca C, Gilon P, Costes S, Bertrand G, Ravier MA. GLP-1 and GIP receptors signal through distinct β-arrestin 2-dependent pathways to regulate pancreatic β cell function. Cell Rep 2023; 42:113326. [PMID: 37897727 DOI: 10.1016/j.celrep.2023.113326] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 09/14/2023] [Accepted: 10/07/2023] [Indexed: 10/30/2023] Open
Abstract
Glucagon-like peptide 1 (GLP-1R) and glucose-dependent insulinotropic polypeptide (GIPR) receptors are G-protein-coupled receptors involved in glucose homeostasis. Diabetogenic conditions decrease β-arrestin 2 (ARRB2) levels in human islets. In mouse β cells, ARRB2 dampens insulin secretion by partially uncoupling cyclic AMP (cAMP)/protein kinase A (PKA) signaling at physiological doses of GLP-1, whereas at pharmacological doses, the activation of extracellular signal-related kinase (ERK)/cAMP-responsive element-binding protein (CREB) requires ARRB2. In contrast, GIP-potentiated insulin secretion needs ARRB2 in mouse and human islets. The GIPR-ARRB2 axis is not involved in cAMP/PKA or ERK signaling but does mediate GIP-induced F-actin depolymerization. Finally, the dual GLP-1/GIP agonist tirzepatide does not require ARRB2 for the potentiation of insulin secretion. Thus, ARRB2 plays distinct roles in regulating GLP-1R and GIPR signaling, and we highlight (1) its role in the physiological context and the possible functional consequences of its decreased expression in pathological situations such as diabetes and (2) the importance of assessing the signaling pathways engaged by the agonists (biased/dual) for therapeutic purposes.
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Affiliation(s)
- Nour Zaïmia
- IGF, Université Montpellier, CNRS, INSERM, Montpellier, France
| | - Joelle Obeid
- IGF, Université Montpellier, CNRS, INSERM, Montpellier, France
| | - Annie Varrault
- IGF, Université Montpellier, CNRS, INSERM, Montpellier, France
| | | | | | - Patrick Gilon
- Université Catholique de Louvain, Institut de Recherche Expérimental et Clinique, Pôle d'Endocrinologie, Diabète, et Nutrition, Brussels, Belgium
| | - Safia Costes
- IGF, Université Montpellier, CNRS, INSERM, Montpellier, France
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2
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Martin-Vega A, Cobb MH. Navigating the ERK1/2 MAPK Cascade. Biomolecules 2023; 13:1555. [PMID: 37892237 PMCID: PMC10605237 DOI: 10.3390/biom13101555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Revised: 10/16/2023] [Accepted: 10/18/2023] [Indexed: 10/29/2023] Open
Abstract
The RAS-ERK pathway is a fundamental signaling cascade crucial for many biological processes including proliferation, cell cycle control, growth, and survival; common across all cell types. Notably, ERK1/2 are implicated in specific processes in a context-dependent manner as in stem cells and pancreatic β-cells. Alterations in the different components of this cascade result in dysregulation of the effector kinases ERK1/2 which communicate with hundreds of substrates. Aberrant activation of the pathway contributes to a range of disorders, including cancer. This review provides an overview of the structure, activation, regulation, and mutational frequency of the different tiers of the cascade; with a particular focus on ERK1/2. We highlight the importance of scaffold proteins that contribute to kinase localization and coordinate interaction dynamics of the kinases with substrates, activators, and inhibitors. Additionally, we explore innovative therapeutic approaches emphasizing promising avenues in this field.
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Affiliation(s)
- Ana Martin-Vega
- Department of Pharmacology, UT Southwestern Medical Center, 6001 Forest Park Rd., Dallas, TX 75390, USA;
| | - Melanie H. Cobb
- Department of Pharmacology, UT Southwestern Medical Center, 6001 Forest Park Rd., Dallas, TX 75390, USA;
- Simmons Comprehensive Cancer Center, UT Southwestern Medical Center, 6001 Forest Park Rd., Dallas, TX 75390, USA
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3
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Basu L, Bhagat V, Ching MEA, Di Giandomenico A, Dostie S, Greenberg D, Greenberg M, Hahm J, Hilton NZ, Lamb K, Jentz EM, Larsen M, Locatelli CAA, Maloney M, MacGibbon C, Mersali F, Mulchandani CM, Najam A, Singh I, Weisz T, Wong J, Senior PA, Estall JL, Mulvihill EE, Screaton RA. Recent Developments in Islet Biology: A Review With Patient Perspectives. Can J Diabetes 2023; 47:207-221. [PMID: 36481263 PMCID: PMC9640377 DOI: 10.1016/j.jcjd.2022.11.003] [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: 09/01/2022] [Revised: 10/24/2022] [Accepted: 11/02/2022] [Indexed: 11/09/2022]
Abstract
Navigating the coronavirus disease-2019 (COVID-19, now COVID) pandemic has required resilience and creativity worldwide. Despite early challenges to productivity, more than 2,000 peer-reviewed articles on islet biology were published in 2021. Herein, we highlight noteworthy advances in islet research between January 2021 and April 2022, focussing on 5 areas. First, we discuss new insights into the role of glucokinase, mitogen-activated protein kinase-kinase/extracellular signal-regulated kinase and mitochondrial function on insulin secretion from the pancreatic β cell, provided by new genetically modified mouse models and live imaging. We then discuss a new connection between lipid handling and improved insulin secretion in the context of glucotoxicity, focussing on fatty acid-binding protein 4 and fetuin-A. Advances in high-throughput "omic" analysis evolved to where one can generate more finely tuned genetic and molecular profiles within broad classifications of type 1 diabetes and type 2 diabetes. Next, we highlight breakthroughs in diabetes treatment using stem cell-derived β cells and innovative strategies to improve islet survival posttransplantation. Last, we update our understanding of the impact of severe acute respiratory syndrome-coronavirus-2 infection on pancreatic islet function and discuss current evidence regarding proposed links between COVID and new-onset diabetes. We address these breakthroughs in 2 settings: one for a scientific audience and the other for the public, particularly those living with or affected by diabetes. Bridging biomedical research in diabetes to the community living with or affected by diabetes, our partners living with type 1 diabetes or type 2 diabetes also provide their perspectives on these latest advances in islet biology.
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Affiliation(s)
- Lahari Basu
- Department of Biology and Institute of Biochemistry, Carleton University, Ottawa, Ontario, Canada
| | - Vriti Bhagat
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada; BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada
| | - Ma Enrica Angela Ching
- Department of Biology and Institute of Biochemistry, Carleton University, Ottawa, Ontario, Canada
| | | | - Sylvie Dostie
- Diabetes Action Canada, Toronto General Hospital, Toronto, Ontario, Canada
| | - Dana Greenberg
- Diabetes Action Canada, Toronto General Hospital, Toronto, Ontario, Canada
| | - Marley Greenberg
- Diabetes Action Canada, Toronto General Hospital, Toronto, Ontario, Canada
| | - Jiwon Hahm
- Department of Physiology and Pharmacology, Western University, London, Ontario, Canada
| | - N Zoe Hilton
- Diabetes Action Canada, Toronto General Hospital, Toronto, Ontario, Canada
| | - Krista Lamb
- Diabetes Action Canada, Toronto General Hospital, Toronto, Ontario, Canada
| | - Emelien M Jentz
- School of Pharmacy, University of Waterloo, Kitchener, Ontario, Canada
| | - Matt Larsen
- Diabetes Action Canada, Toronto General Hospital, Toronto, Ontario, Canada
| | - Cassandra A A Locatelli
- University of Ottawa Heart Institute, Energy Substrate Laboratory, Ottawa, Ontario, Canada; Department of Biochemistry, Immunology and Microbiology, University of Ottawa, Ottawa, Ontario, Canada
| | - MaryAnn Maloney
- Diabetes Action Canada, Toronto General Hospital, Toronto, Ontario, Canada
| | | | - Farida Mersali
- Diabetes Action Canada, Toronto General Hospital, Toronto, Ontario, Canada
| | | | - Adhiyat Najam
- Diabetes Action Canada, Toronto General Hospital, Toronto, Ontario, Canada
| | - Ishnoor Singh
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Tom Weisz
- Diabetes Action Canada, Toronto General Hospital, Toronto, Ontario, Canada
| | - Jordan Wong
- Alberta Diabetes Institute and Department of Pharmacology, Li Ka Shing Centre for Health Research Innovation, University of Alberta, Edmonton, Alberta, Canada; Alberta Diabetes Institute and Department of Surgery, University of Alberta, Edmonton, Alberta, Canada
| | - Peter A Senior
- Alberta Diabetes Institute and Department of Medicine, Edmonton, Alberta, Canada
| | - Jennifer L Estall
- Faculté de Médecine, Université de Montréal, Montréal, Québec, Canada; Institut de recherches cliniques de Montréal, Center for Cardiometabolic Health, Montréal, Québec, Canada
| | - Erin E Mulvihill
- University of Ottawa Heart Institute, Energy Substrate Laboratory, Ottawa, Ontario, Canada; Department of Biochemistry, Immunology and Microbiology, University of Ottawa, Ottawa, Ontario, Canada
| | - Robert A Screaton
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada; Sunnybrook Research Institute, Toronto, Ontario, Canada.
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Al-Romaiyan A, Masocha W, Oyedemi S, Marafie SK, Huang GC, Jones PM, Persaud SJ. Commiphora myrrha stimulates insulin secretion from β-cells through activation of atypical protein kinase C and mitogen-activated protein kinase. JOURNAL OF ETHNOPHARMACOLOGY 2023; 302:115937. [PMID: 36410575 DOI: 10.1016/j.jep.2022.115937] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2022] [Revised: 08/22/2022] [Accepted: 11/11/2022] [Indexed: 06/16/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Ayurvedic medicine has been used in the treatment of diabetes mellitus for centuries. In Arabia and some areas of Africa, Commiphora myrrha (CM) has been extensively used as a plant-based remedy. We have previously shown that an aqueous CM resin solution directly stimulates insulin secretion from MIN6 cells, a mouse β-cell line, and isolated mouse and human islets. However, the signaling pathways involved in CM-induced insulin secretion are completely unknown. Insulin secretion is normally triggered by elevations in intracellular Ca2+ ([Ca2+]i) through voltage gated Ca2+ channels (VGCC) and activation of protein kinases. Protein and lipid kinases such as protein kinase A (PKA), Ca2+-calmodulin dependent protein kinase II (CaMKII), phosphoinositide 3-kinases (PI3Ks), protein kinase C (PKC) and mitogen-activated protein kinase (MAPK), specifically extracellular signal-regulated kinases (ERK1/2), may be involved in receptor-operated insulin secretion. Therefore, we hypothesized that CM may induce insulin secretion by modulating the activity of VGCC and/or one or more of the above kinases. AIM OF THE STUDY To investigate the possible molecular mechanism of action of CM-induced insulin secretion. The effects of aqueous CM resin extract on [Ca2+]i and protein kinase activation from β-cells were examined. METHODS The effect of aqueous CM resin solution on [Ca2+]i was assessed using Ca2+ microfluorimetry. The involvement of VGCC in CM-induced insulin secretion was investigated using static and perifusion insulin secretion experiments in the presence of either EGTA, a Ca2+ chelator, or nifedipine, a blocker of VGCC. The involvement of kinase activation in the stimulatory effect of CM on insulin secretion was examined by using static and perifusion insulin secretion experiments in the presence of known pharmacological inhibitors and/or downregulation of specific kinases. The effects of CM on phosphorylation of PKCζ and ERK1/2 were also assessed using the Wes™ capillary-based protein electrophoresis. RESULTS Ca2+ microfluorimetry measurements showed that exposing MIN6 cells to CM (0.5-2 mg/mL) was not associated with changes in [Ca2+]i. Similarly, incubating MIN6 cells and mouse islets with EGTA and nifedipine, respectively, did not attenuate the insulin secretion induced by CM. However, incubating mouse and human islets with CM in the presence of staurosporine, a non-selective protein kinase inhibitor, completely blocked the effect of CM on insulin secretion. Exposing mouse islets to CM in the presence of H89, KN62 and LY294002, inhibitors of PKA, CaMKII and PI3K, respectively, did not reduce CM-induced insulin secretion. However, incubating mouse and human islets with CM in the presence of Ro 31-8220, a pan-PKC inhibitor, diminished insulin secretion stimulated by CM, whereas inhibiting the action of typical PKC (with Go6976) and PLCβ (with U73122) did not affect CM-stimulated insulin secretion. Similarly, downregulating typical and novel PKC by chronic exposure of mouse islets to phorbol 12-myristate 13-acetate (PMA) was also not associated with a decrease in the stimulatory effect of CM on insulin secretion. Interestingly, CM-induced insulin secretion from mouse islets was inhibited in the presence of the PKCζ inhibitor ZIP and a MAPK inhibitor PD 98059. In addition, Wes™ capillary-based protein electrophoresis indicated that expression of the phosphorylated forms of PKCζ and ERK1/2, a MAPK, was significantly increased following exposure of INS-1832/13 cells, a rat insulinoma cell line, to CM. CONCLUSIONS Our data indicate that CM directly stimulates insulin secretion through activating known downstream effectors of insulin-stimulus secretion coupling. Indeed, the increase in insulin secretion seen with CM is independent of changes in [Ca2+]i and does not involve activation of VGCC. Instead, the CM stimulatory effect on insulin secretion is completely dependent on protein kinase activation. Our findings indicate that CM could induce insulin exocytosis by stimulating the phosphorylation and activation of PKCζ, which in turn phosphorylates and activates ERK1/2.
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Affiliation(s)
- Altaf Al-Romaiyan
- Department of Pharmacology & Therapeutics, Faculty of Pharmacy, Kuwait University, Kuwait.
| | - Willias Masocha
- Department of Pharmacology & Therapeutics, Faculty of Pharmacy, Kuwait University, Kuwait.
| | - Sunday Oyedemi
- School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham, NG11 8NS, UK.
| | - Sulaiman K Marafie
- Biochemistry and Molecular Biology Department, Dasman Diabetes Institute, Kuwait.
| | - Guo-Cai Huang
- Department of Diabetes, School of Cardiovascular Medicine &Sciences, Faculty of Life Sciences and Medicine, King's College London, UK.
| | - Peter M Jones
- Department of Diabetes, School of Cardiovascular Medicine &Sciences, Faculty of Life Sciences and Medicine, King's College London, UK.
| | - Shanta J Persaud
- Department of Diabetes, School of Cardiovascular Medicine &Sciences, Faculty of Life Sciences and Medicine, King's College London, UK.
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RyR2/IRBIT regulates insulin gene transcript, insulin content, and secretion in the insulinoma cell line INS-1. Sci Rep 2022; 12:7713. [PMID: 35562179 PMCID: PMC9095623 DOI: 10.1038/s41598-022-11276-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 03/31/2022] [Indexed: 12/01/2022] Open
Abstract
The role of ER Ca2+ release via ryanodine receptors (RyR) in pancreatic β-cell function is not well defined. Deletion of RyR2 from the rat insulinoma INS-1 (RyR2KO) enhanced IP3 receptor activity stimulated by 7.5 mM glucose, coincident with reduced levels of the protein IP3Receptor Binding protein released with Inositol 1,4,5 Trisphosphate (IRBIT). Insulin content, basal (2.5 mM glucose) and 7.5 mM glucose-stimulated insulin secretion were reduced in RyR2KO and IRBITKO cells compared to controls. INS2 mRNA levels were reduced in both RyR2KO and IRBITKO cells, but INS1 mRNA levels were specifically decreased in RyR2KO cells. Nuclear localization of S-adenosylhomocysteinase (AHCY) was increased in RyR2KO and IRBITKO cells. DNA methylation of the INS1 and INS2 gene promotor regions was very low, and not different among RyR2KO, IRBITKO, and controls, but exon 2 of the INS1 and INS2 genes was more extensively methylated in RyR2KO and IRBITKO cells. Exploratory proteomic analysis revealed that deletion of RyR2 or IRBIT resulted in differential regulation of 314 and 137 proteins, respectively, with 41 in common. These results suggest that RyR2 regulates IRBIT levels and activity in INS-1 cells, and together maintain insulin content and secretion, and regulate the proteome, perhaps via DNA methylation.
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6
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Darden CM, Vasu S, Mattke J, Liu Y, Rhodes CJ, Naziruddin B, Lawrence MC. Calcineurin/NFATc2 and PI3K/AKT signaling maintains β-cell identity and function during metabolic and inflammatory stress. iScience 2022; 25:104125. [PMID: 35402865 PMCID: PMC8983383 DOI: 10.1016/j.isci.2022.104125] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 12/02/2021] [Accepted: 03/16/2022] [Indexed: 11/19/2022] Open
Abstract
Pancreatic islets respond to metabolic and inflammatory stress by producing hormones and other factors that induce adaptive cellular and systemic responses. Here we show that intracellular Ca2+ ([Ca2+]i) and ROS signals generated by high glucose and cytokine-induced ER stress activate calcineurin (CN)/NFATc2 and PI3K/AKT to maintain β-cell identity and function. This was attributed in part by direct induction of the endocrine differentiation gene RFX6 and suppression of several β-cell "disallowed" genes, including MCT1. CN/NFATc2 targeted p300 and HDAC1 to RFX6 and MCT1 promoters to induce and suppress gene transcription, respectively. In contrast, prolonged exposure to stress, hyperstimulated [Ca2+]i, or perturbation of CN/NFATc2 resulted in downregulation of RFX6 and induction of MCT1. These findings reveal that CN/NFATc2 and PI3K/AKT maintain β-cell function during acute stress, but β-cells dedifferentiate to a dysfunctional state upon loss or exhaustion of Ca2+/CN/NFATc2 signaling. They further demonstrate the utility of targeting CN/NFATc2 to restore β-cell function.
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Affiliation(s)
- Carly M. Darden
- Islet Cell Laboratory, Baylor Scott & White Research Institute, Dallas, TX 75204, USA
- Institute of Biomedical Studies, Baylor University, Waco, TX 76706, USA
| | - Srividya Vasu
- Islet Cell Laboratory, Baylor Scott & White Research Institute, Dallas, TX 75204, USA
| | - Jordan Mattke
- Islet Cell Laboratory, Baylor Scott & White Research Institute, Dallas, TX 75204, USA
- Institute of Biomedical Studies, Baylor University, Waco, TX 76706, USA
| | - Yang Liu
- Annette C. and Harold C. Simmons Transplant Institute, Baylor University Medical Center, Dallas, TX 75246, USA
| | - Christopher J. Rhodes
- Kovler Diabetes Center, Department of Medicine, Section of Endocrinology, Diabetes & Metabolism, University of Chicago, Chicago, IL 60637, USA
- Research and Early Development, Cardiovascular, Renal and Metabolic Diseases, BioPharmaceuticals R&D, AstraZeneca Ltd, Gaithersburg, MD 20878, USA
| | - Bashoo Naziruddin
- Annette C. and Harold C. Simmons Transplant Institute, Baylor University Medical Center, Dallas, TX 75246, USA
| | - Michael C. Lawrence
- Islet Cell Laboratory, Baylor Scott & White Research Institute, Dallas, TX 75204, USA
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7
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Rodriguez-Rodriguez AE, Porrini E, Torres A. Beta-Cell Dysfunction Induced by Tacrolimus: A Way to Explain Type 2 Diabetes? Int J Mol Sci 2021; 22:ijms221910311. [PMID: 34638652 PMCID: PMC8509035 DOI: 10.3390/ijms221910311] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 09/01/2021] [Accepted: 09/14/2021] [Indexed: 01/01/2023] Open
Abstract
The combination of insulin resistance and β-cells dysfunction leads to the onset of type-2 diabetes mellitus (T2DM). This process can last for decades, as β-cells are able to compensate the demand for insulin and maintain normoglycemia. Understanding the adaptive capacity of β-cells during this process and the causes of its failure is essential to the limit onset of diabetes. Post-transplant diabetes mellitus (PTDM) is a common and serious disease that affects 30% of renal transplant recipients. With the exception of immunosuppressive therapy, the risk factors for T2D are the same as for PTDM: obesity, dyslipidaemia, insulin resistance and metabolic syndrome. Tacrolimus (TAC) is the immunosuppressant of choice after renal transplantation but it has the highest rates of PTDM. Our group has shown that insulin resistance and glucolipotoxicity, without favouring the appearance of apoptosis, modify key nuclear factors for the maintenance of identity and functionality of β-cells. In this context, TAC accelerates or enhances these changes. Our hypothesis is that the pathways that are affected in the progression from pre-diabetes to diabetes in the general population are the same pathways that are affected by TAC. So, TAC can be considered a tool to study the pathogenesis of T2DM. Here, we review the common pathways of β-cells dysfunction on T2DM and TAC-induced diabetes.
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Affiliation(s)
- Ana Elena Rodriguez-Rodriguez
- Research Unit, Hospital Universitario de Canarias, 38320 La Laguna, Santa Cruz de Tenerife, Spain;
- Fundación General de la Universidad, Universidad de La Laguna, 38204 La Laguna, Santa Cruz de Tenerife, Spain
| | - Esteban Porrini
- Unidad Ensayos Clinicos-UCICEC, Hospital Universitario de Canarias, 38320 La Laguna, Santa Cruz de Tenerife, Spain;
- Instituto Tecnologías Biomédicas (ITB), Universidad de La Laguna, 38200 La Laguna, Santa Cruz de Tenerife, Spain
- Correspondence: ; Tel.: +34-922-678-116
| | - Armando Torres
- Unidad Ensayos Clinicos-UCICEC, Hospital Universitario de Canarias, 38320 La Laguna, Santa Cruz de Tenerife, Spain;
- Nephrology Department, Hospital Universitario de Canarias, 38320 La Laguna, Santa Cruz de Tenerife, Spain
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8
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Madec AM, Perrier J, Panthu B, Dingreville F. Role of mitochondria-associated endoplasmic reticulum membrane (MAMs) interactions and calcium exchange in the development of type 2 diabetes. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2021; 363:169-202. [PMID: 34392929 DOI: 10.1016/bs.ircmb.2021.06.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Glucotoxicity-induced β-cell dysfunction in type 2 diabetes is associated with alterations of mitochondria and the endoplasmic reticulum (ER). Mitochondria and ER form a network in cells that controls cell function and fate. Mitochondria of the pancreatic β cell play a central role in the secretion of insulin in response to glucose through their ability to produce ATP. Both organelles interact at contact sites, defined as mitochondria-associated membranes (MAMs), which were recently implicated in the regulation of glucose homeostasis. Here, we review MAM functions in the cell and we focus on the crosstalk between the ER and Mitochondria in the context of T2D, highlighting the pivotal role played by MAMs especially in β cells through inter-organelle calcium exchange and glucotoxicity-associated β cell dysfunction.
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Affiliation(s)
| | - Johan Perrier
- CarMeN Laboratory, INSERM U1060, INRA U1397, Lyon, France
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9
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Ikushima YM, Awazawa M, Kobayashi N, Osonoi S, Takemiya S, Kobayashi H, Suwanai H, Morimoto Y, Soeda K, Adachi J, Muratani M, Charron J, Mizukami H, Takahashi N, Ueki K. MEK/ERK Signaling in β-Cells Bifunctionally Regulates β-Cell Mass and Glucose-Stimulated Insulin Secretion Response to Maintain Glucose Homeostasis. Diabetes 2021; 70:1519-1535. [PMID: 33906910 DOI: 10.2337/db20-1295] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 04/23/2021] [Indexed: 11/13/2022]
Abstract
In diabetic pathology, insufficiency in β-cell mass, unable to meet peripheral insulin demand, and functional defects of individual β-cells in production of insulin are often concurrently observed, collectively causing hyperglycemia. Here we show that the phosphorylation of ERK1/2 is significantly decreased in the islets of db/db mice as well as in those of a cohort of subjects with type 2 diabetes. In mice with abrogation of ERK signaling in pancreatic β-cells through deletion of Mek1 and Mek2, glucose intolerance aggravates under high-fat diet-feeding conditions due to insufficient insulin production with lower β-cell proliferation and reduced β-cell mass, while in individual β-cells dampening of the number of insulin exocytosis events is observed, with the molecules involved in insulin exocytosis being less phosphorylated. These data reveal bifunctional roles for MEK/ERK signaling in β-cells for glucose homeostasis, i.e., in regulating β-cell mass as well as in controlling insulin exocytosis in individual β-cells, thus providing not only a novel perspective for the understanding of diabetes pathophysiology but also a potential clue for new drug development for diabetes treatment.
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Affiliation(s)
- Yoshiko Matsumoto Ikushima
- Department of Molecular Diabetic Medicine, Diabetes Research Center, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan
| | - Motoharu Awazawa
- Department of Molecular Diabetic Medicine, Diabetes Research Center, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan
| | - Naoki Kobayashi
- Department of Molecular Diabetic Medicine, Diabetes Research Center, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan
| | - Sho Osonoi
- Department of Pathology and Molecular Medicine, Hirosaki University Graduate School of Medicine, Hirosaki, Japan
| | - Seiichi Takemiya
- Department of Molecular Diabetic Medicine, Diabetes Research Center, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan
| | - Hiroshi Kobayashi
- Department of Stem Cell Biology, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan
| | - Hirotsugu Suwanai
- Department of Diabetes, Metabolism and Endocrinology, Tokyo Medical University, Tokyo, Japan
| | - Yuichi Morimoto
- Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, Faculty of Medicine, The University of Tokyo, Tokyo, Japan
- International Research Center for Neurointelligence (WPI-IRCN), University of Tokyo Institutes for Advanced Study (UTIAS), The University of Tokyo, Tokyo, Japan
| | - Kotaro Soeda
- Department of Molecular Diabetic Medicine, Diabetes Research Center, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan
| | - Jun Adachi
- Laboratory of Proteome Research, Laboratory of Proteomics for Drug Discovery, Center for Drug Design Research, National Institutes of Biomedical Innovation, Health and Nutrition, Osaka, Japan
| | - Masafumi Muratani
- Department of Genome Biology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Jean Charron
- Centre de Recherche sur le Cancer de l'Université Laval, L'Hôtel-Dieu de Québec, Quebec City, Quebec, Canada
| | - Hiroki Mizukami
- Department of Pathology and Molecular Medicine, Hirosaki University Graduate School of Medicine, Hirosaki, Japan
| | - Noriko Takahashi
- Department of Physiology, Kitasato University School of Medicine, Sagamihara, Japan
| | - Kohjiro Ueki
- Department of Molecular Diabetic Medicine, Diabetes Research Center, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan
- Department of Molecular Diabetology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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10
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Xiao F, Li H, Feng Z, Huang L, Kong L, Li M, Wang D, Liu F, Zhu Z, Wei Y, Zhang W. Intermedin facilitates hepatocellular carcinoma cell survival and invasion via ERK1/2-EGR1/DDIT3 signaling cascade. Sci Rep 2021; 11:488. [PMID: 33436794 PMCID: PMC7803743 DOI: 10.1038/s41598-020-80066-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Accepted: 12/14/2020] [Indexed: 02/06/2023] Open
Abstract
As one of the most malignant cancer types, hepatocellular carcinoma (HCC) is highly invasive and capable of metastasizing to distant organs. Intermedin (IMD), an endogenous peptide belonging to the calcitonin family, has been suggested playing important roles in cancer cell survival and invasion, including in HCC. However, how IMD affects the behavior of HCC cells and the underlying mechanisms have not been fully elucidated. Here, we show that IMD maintains an important homeostatic state by activating the ERK1/2-EGR1 (early growth response 1) signaling cascade, through which HCC cells acquire a highly invasive ability via significantly enhanced filopodia formation. The inhibition of IMD blocks the phosphorylation of ERK1/2, resulting in EGR1 downregulation and endoplasmic reticulum stress (ER) stress, which is evidenced by the upregulation of ER stress marker DDIT3 (DNA damage-inducible transcript 3). The high level of DDIT3 induces HCC cells into an ER-stress related apoptotic pathway. Along with our previous finding that IMD plays critical roles in the vascular remodeling process that improves tumor blood perfusion, IMD may facilitate the acquisition of increased invasive abilities and a survival benefit by HCC cells, and it is easier for HCC cells to obtain blood supply via the vascular remodeling activities of IMD. According to these results, blockade of IMD activity may have therapeutic potential in the treatment of HCC.
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Affiliation(s)
- Fei Xiao
- Department of Intensive Care Unit of Gynecology and Obstetrics, West China Second University Hospital, Sichuan University, Chengdu, People's Republic of China
| | - Hongyu Li
- Liver Transplantation Center, Beijing Friendship Hospital, Capital Medical University, Beijing, People's Republic of China
| | - Zhongxue Feng
- Department of Critical Care Medicine, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center of Biotherapy, No. 1, Ke Yuan 4th Road, Gao Peng Street, Chengdu, 610041, Sichuan, People's Republic of China
| | - Luping Huang
- Department of Critical Care Medicine, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center of Biotherapy, No. 1, Ke Yuan 4th Road, Gao Peng Street, Chengdu, 610041, Sichuan, People's Republic of China
| | - Lingmiao Kong
- Department of Critical Care Medicine, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center of Biotherapy, No. 1, Ke Yuan 4th Road, Gao Peng Street, Chengdu, 610041, Sichuan, People's Republic of China
| | - Min Li
- Department of Critical Care Medicine, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center of Biotherapy, No. 1, Ke Yuan 4th Road, Gao Peng Street, Chengdu, 610041, Sichuan, People's Republic of China
| | - Denian Wang
- Department of Critical Care Medicine, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center of Biotherapy, No. 1, Ke Yuan 4th Road, Gao Peng Street, Chengdu, 610041, Sichuan, People's Republic of China
| | - Fei Liu
- Department of Liver Surgery, West China Hospital, Sichuan University, No. 1, Ke Yuan 4th Road, Gao Peng Street, Chengdu, 610041, Sichuan, People's Republic of China
| | - Zhijun Zhu
- Liver Transplantation Center, Beijing Friendship Hospital, Capital Medical University, Beijing, People's Republic of China.
| | - Yong'gang Wei
- Department of Liver Surgery, West China Hospital, Sichuan University, No. 1, Ke Yuan 4th Road, Gao Peng Street, Chengdu, 610041, Sichuan, People's Republic of China.
| | - Wei Zhang
- Department of Critical Care Medicine, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center of Biotherapy, No. 1, Ke Yuan 4th Road, Gao Peng Street, Chengdu, 610041, Sichuan, People's Republic of China.
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11
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Kalwat MA, Huang Z, Binns DD, McGlynn K, Cobb MH. α 2-Adrenergic Disruption of β Cell BDNF-TrkB Receptor Tyrosine Kinase Signaling. Front Cell Dev Biol 2020; 8:576396. [PMID: 33178692 PMCID: PMC7593622 DOI: 10.3389/fcell.2020.576396] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 09/14/2020] [Indexed: 12/11/2022] Open
Abstract
Adrenergic signaling is a well-known input into pancreatic islet function. Specifically, the insulin-secreting islet β cell expresses the Gi/o-linked α2-adrenergic receptor, which upon activation suppresses insulin secretion. The use of the adrenergic agonist epinephrine at micromolar doses may have supraphysiological effects. We found that pretreating β cells with micromolar concentrations of epinephrine differentially inhibited activation of receptor tyrosine kinases. We chose TrkB as an example because of its relative sensitivity to the effects of epinephrine and due to its potential regulatory role in the β cell. Our characterization of brain-derived neurotrophic factor (BDNF)-TrkB signaling in MIN6 β cells showed that TrkB is activated by BDNF as expected, leading to canonical TrkB autophosphorylation and subsequent downstream signaling, as well as chronic effects on β cell growth. Micromolar, but not nanomolar, concentrations of epinephrine blocked BDNF-induced TrkB autophosphorylation and downstream mitogen-activated protein kinase pathway activation, suggesting an inhibitory phenomenon at the receptor level. We determined epinephrine-mediated inhibition of TrkB activation to be Gi/o-dependent using pertussis toxin, arguing against an off-target effect of high-dose epinephrine. Published data suggested that inhibition of potassium channels or phosphoinositide-3-kinase signaling may abrogate the negative effects of epinephrine; however, these did not rescue TrkB signaling in our experiments. Taken together, these results show that (1) TrkB kinase signaling occurs in β cells and (2) use of epinephrine in studies of insulin secretion requires careful consideration of concentration-dependent effects. BDNF-TrkB signaling in β cells may underlie pro-survival or growth signaling and warrants further study.
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Affiliation(s)
- Michael A. Kalwat
- Department of Pharmacology, UT Southwestern Medical Center, Dallas, TX, United States
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12
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Hu W, Ding Y, Li Q, shi R, He Y. Transient receptor potential vanilloid 4 channels as therapeutic targets in diabetes and diabetes-related complications. J Diabetes Investig 2020; 11:757-769. [PMID: 32129549 PMCID: PMC7378409 DOI: 10.1111/jdi.13244] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 01/21/2020] [Accepted: 02/27/2020] [Indexed: 12/12/2022] Open
Abstract
With an estimated 425 million diabetes patients worldwide in 2019, type 2 diabetes has reached a pandemic proportion and represents a major unmet medical need. A key determinant of the development and progression of type 2 diabetes is pancreatic -cell dysfunction, including the loss of cell mass, the impairment of insulin biosynthesis and inadequate exocytosis. Recent studies have shown that transient receptor potential vanilloid 4 (TRPV4), a Ca2+ -permeable non-selective cation channel, is involved in -cell replication, insulin production and secretion. TRPV4 agonists have insulinotropic activity in pancreatic -cell lines, but the prolonged activation of TRPV4 leads to -cell dysfunction and death. In addition, TRPV4 is involved in a wide variety of pathophysiological activities, and has been reported to play an important role in diabetes-related complications, such as obesity, cardiovascular diseases, diabetic retinopathy, nephropathy and neuropathy. In a rodent type 2 diabetes model, Trpv4 agonists promote vasodilation and improve cardiovascular function, whereas Trpv4 antagonists reduce high-fat diet-induced obesity, insulin resistance, diabetic nephropathy, retinopathy and neuropathy. These findings raise interest in using TRPV4 as a therapeutic target for type 2 diabetes. In this review, we intend to summarize the latest findings regarding the role of TRPV4 in diabetes as well as diabetes-related conditions, and to evaluate its potential as a therapeutic target for diabetes and diabetes-related diseases.
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Affiliation(s)
- Wei Hu
- Department of Epidemiology and Medical StatisticsInstitute of Medical Systems BiologyGuangdong Medical UniversityDongguanChina
| | - Yuanlin Ding
- Department of Epidemiology and Medical StatisticsInstitute of Medical Systems BiologyGuangdong Medical UniversityDongguanChina
| | - Qingqing Li
- Department of Epidemiology and Medical StatisticsInstitute of Medical Systems BiologyGuangdong Medical UniversityDongguanChina
| | - Rou shi
- Department of Epidemiology and Medical StatisticsInstitute of Medical Systems BiologyGuangdong Medical UniversityDongguanChina
| | - Yuqing He
- Department of Epidemiology and Medical StatisticsInstitute of Medical Systems BiologyGuangdong Medical UniversityDongguanChina
- Liaobu HospitalGuangdong Medical UniversityDongguanChina
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13
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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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14
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Emamgholipour S, Ebrahimi R, Bahiraee A, Niazpour F, Meshkani R. Acetylation and insulin resistance: a focus on metabolic and mitogenic cascades of insulin signaling. Crit Rev Clin Lab Sci 2020:1-19. [DOI: 10.1080/10408363.2019.1699498] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Solaleh Emamgholipour
- Department of Clinical Biochemistry, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Reyhane Ebrahimi
- Department of Clinical Biochemistry, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
- Students’ Scientific Research Center (SSRC), Tehran University of Medical Sciences, Tehran, Iran
| | - Alireza Bahiraee
- Department of Medical Genetics, Faculty of Medicine, Hormozgan University of Medical Sciences, Bandar Abbas, Iran
| | - Farshad Niazpour
- Department of Clinical Biochemistry, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Reza Meshkani
- Department of Clinical Biochemistry, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
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15
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Đorđević M, Grdović N, Mihailović M, Arambašić Jovanović J, Uskoković A, Rajić J, Sinadinović M, Tolić A, Mišić D, Šiler B, Poznanović G, Vidaković M, Dinić S. Centaurium erythraea extract improves survival and functionality of pancreatic beta-cells in diabetes through multiple routes of action. JOURNAL OF ETHNOPHARMACOLOGY 2019; 242:112043. [PMID: 31252092 DOI: 10.1016/j.jep.2019.112043] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 06/24/2019] [Accepted: 06/24/2019] [Indexed: 06/09/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Centaurium erythraea Rafn (CE) is used as a traditional medicinal plant in Serbia to treat different ailments due to its antidiabetic, antipyretic, antiflatulent and detoxification effects. AIM OF THE STUDY Elucidation of the mechanisms that underlie the antioxidant and pro-survival effects of the CE extract (CEE) in beta-cells and pancreatic islets from streptozotocin (STZ)-treated diabetic rats. MATERIAL AND METHODS Diabetes was induced in rats by multiple applications of low doses of STZ (40 mg/kg intraperitoneally (i.p.), for five consecutive days). CEE (100 mg/kg) was administered orally, in the pre-treated group for two weeks before diabetes induction, during the treatments with STZ and for four weeks after diabetes onset, and in the post-treatment group for four weeks after diabetes induction. The impact of CEE on diabetic islets was estimated by histological and immunohistochemical examination of the pancreas. Molecular mechanisms of the effects of CEE were also analyzed in insulinoma Rin-5F cells treated with STZ (12 mM) and CEE (0.25 mg/mL). Oxidative stress was evaluated by assessing the levels of DNA damage, lipid peroxidation, protein S-glutathionylation and enzymatic activities and expression of CAT, MnSOD, CuZnSOD, GPx and GR in beta-cells. The presence and activities of the redox-sensitive and islet-enriched regulatory proteins were also analyzed. RESULTS Treatment with CEE ameliorated the insulin level and glycemic control in STZ-induced diabetic rats by improving the structural and functional properties of pancreatic islets through multiple routes of action. The disturbance of islet morphology and islet cell contents in diabetes was reduced by the CEE treatment and was associated with a protective effect of CEE on the levels of insulin, GLUT-2 and p-Akt in diabetic islets. The antioxidant effect of CEE on STZ-treated beta-cells was displayed as reduced DNA damage, lipid peroxidation, protein S-glutathionylation and alleviation of STZ-induced disruption in MnSOD, CuZnSOD and CAT enzyme activities. The oxidative stress-induced disturbance of the transcriptional regulation of CAT, MnSOD, CuZnSOD, GPx and GR enzymes in beta-cells was improved after the CEE treatment, and was observed as readjustment of the presence and activities of redox-sensitive NFκB-p65, FOXO3A, Sp1 and Nrf-2 transcription factors. The observed CEE-mediated induction of proliferative and pro-survival pathways and insulin expression/secretion after STZ-induced oxidative stress in beta-cells could be partially attributed to a fine-tuned modulation of the activities of pro-survival Akt, ERK and p38 kinases and islet-enriched Pdx-1 and MafA regulatory factors. CONCLUSIONS The results of this study provide evidence that CEE improves the structural and functional properties of pancreatic beta-cells by correcting the endogenous antioxidant regulatory mechanisms and by promoting proliferative and pro-survival pathways in beta-cells.
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Affiliation(s)
- Miloš Đorđević
- Department of Molecular Biology, Institute for Biological Research "Siniša Stanković", University of Belgrade, Bulevar despota Stefana 142, 11060, Belgrade, Serbia.
| | - Nevena Grdović
- Department of Molecular Biology, Institute for Biological Research "Siniša Stanković", University of Belgrade, Bulevar despota Stefana 142, 11060, Belgrade, Serbia.
| | - Mirjana Mihailović
- Department of Molecular Biology, Institute for Biological Research "Siniša Stanković", University of Belgrade, Bulevar despota Stefana 142, 11060, Belgrade, Serbia.
| | - Jelena Arambašić Jovanović
- Department of Molecular Biology, Institute for Biological Research "Siniša Stanković", University of Belgrade, Bulevar despota Stefana 142, 11060, Belgrade, Serbia.
| | - Aleksandra Uskoković
- Department of Molecular Biology, Institute for Biological Research "Siniša Stanković", University of Belgrade, Bulevar despota Stefana 142, 11060, Belgrade, Serbia.
| | - Jovana Rajić
- Department of Molecular Biology, Institute for Biological Research "Siniša Stanković", University of Belgrade, Bulevar despota Stefana 142, 11060, Belgrade, Serbia.
| | - Marija Sinadinović
- Department of Molecular Biology, Institute for Biological Research "Siniša Stanković", University of Belgrade, Bulevar despota Stefana 142, 11060, Belgrade, Serbia.
| | - Anja Tolić
- Department of Molecular Biology, Institute for Biological Research "Siniša Stanković", University of Belgrade, Bulevar despota Stefana 142, 11060, Belgrade, Serbia.
| | - Danijela Mišić
- Department of Plant Physiology, Institute for Biological Research "Siniša Stanković", University of Belgrade, Bulevar despota Stefana 142, 11060, Belgrade, Serbia.
| | - Branislav Šiler
- Department of Plant Physiology, Institute for Biological Research "Siniša Stanković", University of Belgrade, Bulevar despota Stefana 142, 11060, Belgrade, Serbia.
| | - Goran Poznanović
- Department of Molecular Biology, Institute for Biological Research "Siniša Stanković", University of Belgrade, Bulevar despota Stefana 142, 11060, Belgrade, Serbia.
| | - Melita Vidaković
- Department of Molecular Biology, Institute for Biological Research "Siniša Stanković", University of Belgrade, Bulevar despota Stefana 142, 11060, Belgrade, Serbia.
| | - Svetlana Dinić
- Department of Molecular Biology, Institute for Biological Research "Siniša Stanković", University of Belgrade, Bulevar despota Stefana 142, 11060, Belgrade, Serbia.
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16
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Ebrahimi R, Bahiraee A, Niazpour F, Emamgholipour S, Meshkani R. The role of microRNAs in the regulation of insulin signaling pathway with respect to metabolic and mitogenic cascades: A review. J Cell Biochem 2019; 120:19290-19309. [PMID: 31364207 DOI: 10.1002/jcb.29299] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 06/27/2019] [Indexed: 12/18/2022]
Abstract
Insulin resistance (IR) is a shared pathological condition among type 2 diabetes, obesity, cardiovascular disease, and other metabolic disorders. It is growing significantly all over the world and consequently, a substantial effort is needed for developing the potential novel diagnostics and therapeutics. An insulin signaling pathway is tightly modulated by different mechanisms including the epigenetic modifications. Today, a deal of great attention has been shifted towards the regulatory role of noncoding RNAs on target proteins of the insulin signaling pathway. Noncoding RNAs are a major area of the epigenetics which control gene expression at the posttranscriptional levels and include a large class of microRNAs (miRNAs). With this in view, many studies have implicated the mediatory effects of miRNAs on the downstream metabolic and mitogenic proteins of the insulin signaling pathway. Since providing new biomarkers for the early diagnosis of IR and related metabolic traits are very significant, we intended to review the possible role of miRNAs in the regulation of the insulin signaling pathway, with a primary focus on the downstream target proteins of the metabolic and mitogenic cascades.
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Affiliation(s)
- Reyhane Ebrahimi
- Department of Clinical Biochemistry, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.,Students' Scientific Research Center (SSRC), Tehran University of Medical Sciences, Tehran, Iran
| | - Alireza Bahiraee
- Department of Medical Genetics, Faculty of Medicine, Hormozgan University of Medical Sciences, Bandar Abbas, Iran
| | - Farshad Niazpour
- Department of Clinical Biochemistry, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Solaleh Emamgholipour
- Department of Clinical Biochemistry, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Reza Meshkani
- Department of Clinical Biochemistry, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
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17
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Lee T, Yun S, Jeong JH, Jung TW. Asprosin impairs insulin secretion in response to glucose and viability through TLR4/JNK-mediated inflammation. Mol Cell Endocrinol 2019; 486:96-104. [PMID: 30853600 DOI: 10.1016/j.mce.2019.03.001] [Citation(s) in RCA: 87] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 03/02/2019] [Accepted: 03/04/2019] [Indexed: 01/02/2023]
Abstract
Severe inflammation in the islets is observed in obese patients with type 2 diabetes. Inflammation in the islets is caused by obesity-induced serum free fatty acids. Asprosin is a fasting-induced adipokine, which contributes to hepatic glucose production. However, the effects of asprosin on inflammation and cellular dysfunction in pancreatic β-cells remain to be elucidated. Here, we demonstrated that treatment of mouse insulinoma MIN6 cells and human primary islets containing β-cells with palmitate increased asprosin expression and secretion. Treatment of MIN6 cells and human primary islets with palmitate increased phosphorylation of the inflammatory marker nuclear factor-kappa B (NFκB) and the release of pro-inflammatory cytokines including TNF and MCP-1 and decreased glucose-stimulated insulin secretion and cell viability. However, siRNA-mediated suppression of asprosin reversed these changes. Recombinant asprosin treatment of MIN6 cells and human primary islets augmented the inflammation response, cellular dysfunction, and apoptosis in a dose-dependent manner. Asprosin induced toll-like receptor (TLR) 4 expression and JNK phosphorylation. siRNA for TLR4 or JNK mitigated the effects of asprosin on inflammation and cellular dysfunction. These results suggest that palmitate-derived asprosin secretion from β-cells results in their inflammation and dysfunction through a TLR4/JNK-mediated pathway. This report suggests asprosin as a novel therapeutic target for the treatment of type 2 diabetes through preservation of β-cell function.
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Affiliation(s)
- Taeseung Lee
- Department of Surgery, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, South Korea; Department of Surgery, Seoul National University College of Medicine, Seoul, South Korea
| | - Subin Yun
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY, USA
| | - Ji Hoon Jeong
- Department of Pharmacology, College of Medicine, Chung-Ang University, Seoul, South Korea
| | - Tae Woo Jung
- Department of Pharmacology, College of Medicine, Chung-Ang University, Seoul, South Korea.
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18
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Michael ES, Covic L, Kuliopulos A. Trace amine-associated receptor 1 (TAAR1) promotes anti-diabetic signaling in insulin-secreting cells. J Biol Chem 2019; 294:4401-4411. [PMID: 30670596 DOI: 10.1074/jbc.ra118.005464] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 01/16/2019] [Indexed: 12/25/2022] Open
Abstract
Pancreatic β-cell failure in type 2 diabetes mellitus is a serious challenge that results in an inability of the pancreas to produce sufficient insulin to properly regulate blood glucose levels. Trace amine-associated receptor 1 (TAAR1) is a G protein-coupled receptor expressed by β-cells that has recently been proposed as a potential target for improving glycemic control and suppressing binge eating behaviors. We discovered that TAAR1 is coupled to Gαs-signaling pathways in insulin-secreting β-cells to cause protein kinase A (PKA)/exchange protein activated by cAMP (Epac)-dependent release of insulin, activation of RAF proto-oncogene, Ser/Thr kinase (Raf)-mitogen-activated protein kinase (MAPK) signaling, induction of cAMP response element-binding protein (CREB)-insulin receptor substrate 2 (Irs-2), and increased β-cell proliferation. Interestingly, TAAR1 triggered cAMP-mediated calcium influx and release from internal stores, both of which were required for activation of a MAPK cascade utilizing calmodulin-dependent protein kinase II (CaMKII), Raf, and MAPK/ERK kinase 1/2 (MEK1/2). Together, these data identify TAAR1/Gαs-mediated signaling pathways that promote insulin secretion, improved β-cell function and proliferation, and highlight TAAR1 as a promising new target for improving β-cell health in type 2 diabetes mellitus.
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Affiliation(s)
- Emily S Michael
- From the Center for Hemostasis and Thrombosis Research, Tufts Medical Center, Department of Medicine, Tufts University School of Graduate Biomedical Sciences/Biochemistry, Tufts University School of Medicine, Boston, Massachusetts 02111
| | - Lidija Covic
- From the Center for Hemostasis and Thrombosis Research, Tufts Medical Center, Department of Medicine, Tufts University School of Graduate Biomedical Sciences/Biochemistry, Tufts University School of Medicine, Boston, Massachusetts 02111
| | - Athan Kuliopulos
- From the Center for Hemostasis and Thrombosis Research, Tufts Medical Center, Department of Medicine, Tufts University School of Graduate Biomedical Sciences/Biochemistry, Tufts University School of Medicine, Boston, Massachusetts 02111
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19
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Li J, Wang Z, Ren L, Fan L, Liu W, Jiang Y, Lau HK, Liu R, Wang Q. Antagonistic interaction between Nodal and insulin modulates pancreatic β-cell proliferation and survival. Cell Commun Signal 2018; 16:79. [PMID: 30409165 PMCID: PMC6225724 DOI: 10.1186/s12964-018-0288-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Accepted: 10/25/2018] [Indexed: 12/21/2022] Open
Abstract
Background Insulin signaling pathway in β-cell is essential to promote β-cells proliferation and survival, while Nodal–ALK7–Smad3 signaling involves β-cells apoptosis. We attempted to address inter-relationship between Nodal and insulin in modulating β-cell proliferation and apoptosis. Methods Using INS-1 β-cells and isolated rat islets, we examined the effects of Nodal, insulin, or the two combined on β-cell proliferation and/or apoptosis. Results The β-cells under high-glucose or palmitate conditions showed significant up-regulation of Nodal expression and activation of its downstream signaling pathway resulted in increased cleaved caspase-3. Insulin treatment led to significantly attenuated Nodal-induced cell apoptotic pathway. Similar results were found in directly Nodal-treated β-cell that insulin could partially block Nodal-induced up-regulation of ALK7–Smad3–caspase-3 signaling pathways with significantly attenuated β-cell apoptosis. Interestingly, we found that insulin-induced Akt activation and downstream molecules including GSK-3β, β-catenin and ERK1/2 was significantly attenuated by the co-treatment with Nodal, resulted in decreased cell proliferation. Furthermore, Nodal decreased glucose-evoked calcium influx and played a negative role during glucose-stimulated insulin secretion in the β-cells. Immunocytochemistry studies showed that Nodal treatment translocated Smad3 from cytosol mostly to the nucleus; however, co-treatment with insulin significantly decreased Smad3 nuclear localization. Co-immunoprecipitation experiments showed a directly interaction between Smad3 and Akt, and this interaction was enhanced by co-treatment with insulin. Conclusions Our data suggest that the antagonistic interaction between Nodal and insulin has a role in the regulation of β-cell mass and secretion. Electronic supplementary material The online version of this article (10.1186/s12964-018-0288-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Junfeng Li
- Department of Endocrinology and Metabolism, Huashan Hospital, Fudan University, Shanghai, China.,Department of Endocrinology, Renmin Hospital of Wuhan University, Wuhan, China
| | - Zhihong Wang
- Department of Endocrinology and Metabolism, Huashan Hospital, Fudan University, Shanghai, China
| | - Liwei Ren
- Department of Endocrinology and Metabolism, Huashan Hospital, Fudan University, Shanghai, China
| | - Linling Fan
- Department of Endocrinology and Metabolism, Huashan Hospital, Fudan University, Shanghai, China
| | - Wenjuan Liu
- Department of Endocrinology and Metabolism, Huashan Hospital, Fudan University, Shanghai, China
| | - Yaojing Jiang
- Department of Endocrinology and Metabolism, Huashan Hospital, Fudan University, Shanghai, China
| | - Harry K Lau
- Division of Endocrinology and Metabolism, Keenan Research Centre for Biomedical Science of St. Michael's Hospital, Toronto, Ontario, Canada.,Department of Physiology and Medicine, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Rui Liu
- Department of Endocrinology and Metabolism, Huashan Hospital, Fudan University, Shanghai, China
| | - Qinghua Wang
- Department of Endocrinology and Metabolism, Huashan Hospital, Fudan University, Shanghai, China. .,Division of Endocrinology and Metabolism, Keenan Research Centre for Biomedical Science of St. Michael's Hospital, Toronto, Ontario, Canada. .,Department of Physiology and Medicine, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
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20
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Rachdaoui N, Polo-Parada L, Ismail-Beigi F. Prolonged Exposure to Insulin Inactivates Akt and Erk 1/2 and Increases Pancreatic Islet and INS1E β-Cell Apoptosis. J Endocr Soc 2018; 3:69-90. [PMID: 30697602 PMCID: PMC6344346 DOI: 10.1210/js.2018-00140] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 10/29/2018] [Indexed: 12/18/2022] Open
Abstract
Chronic hyperinsulinemia, in vivo, increases the resistance of peripheral tissues to insulin by desensitizing insulin signaling. Insulin, in a heterologous manner, can also cause IGF-1 resistance. The aim of the current study was to investigate whether insulin-mediated insulin and IGF-1 resistance develops in pancreatic β-cells and whether this resistance results in β-cell decompensation. Chronic exposure of rat islets or INS1E β-cells to increasing concentrations of insulin decreased AktS473 phosphorylation in response to subsequent acute stimulation with 10 nM insulin or IGF-1. Prolonged exposure to high insulin levels not only inhibited AktS473 phosphorylation, but it also resulted in a significant inhibition of the phosphorylation of P70S6 kinase and Erk1/2 phosphorylation in response to the acute stimulation by glucose, insulin, or IGF-1. Decreased activation of Akt, P70S6K, and Erk1/2 was associated with decreased insulin receptor substrate 2 tyrosine phosphorylation and insulin receptor β-subunit abundance; neither IGF receptor β-subunit content nor its phosphorylation were affected. These signaling impairments were associated with decreased SERCA2 expression, perturbed plasma membrane calcium current and intracellular calcium handling, increased endoplasmic reticulum stress markers such as eIF2αS51 phosphorylation and Bip (GRP78) expression, and increased islet and β-cell apoptosis. We demonstrate that prolonged exposure to high insulin levels induces not only insulin resistance, but in a heterologous manner causes resistance to IGF-1 in rat islets and insulinoma cells resulting in decreased cell survival. These findings suggest the possibility that chronic exposure to hyperinsulinemia may negatively affect β-cell mass by increasing β-cell apoptosis.
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Affiliation(s)
- Nadia Rachdaoui
- Division of Clinical and Molecular Endocrinology, Department of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - Luis Polo-Parada
- Department of Medical Pharmacology and Physiology, Dalton Cardiovascular Research Center, University of Missouri-Columbia, Columbia, Missouri
| | - Faramarz Ismail-Beigi
- Division of Clinical and Molecular Endocrinology, Department of Medicine, Case Western Reserve University, Cleveland, Ohio
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Sidarala V, Kowluru A. The Regulatory Roles of Mitogen-Activated Protein Kinase (MAPK) Pathways in Health and Diabetes: Lessons Learned from the Pancreatic β-Cell. ACTA ACUST UNITED AC 2017; 10:76-84. [PMID: 27779078 DOI: 10.2174/1872214810666161020154905] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 10/17/2016] [Accepted: 10/17/2016] [Indexed: 01/14/2023]
Abstract
BACKGROUND Glucose-stimulated insulin secretion (GSIS) from the pancreatic β-cell involves several intracellular metabolic events which lead to the translocation of insulin granules towards the membrane for fusion and release. It is well established that loss of β-cell function and decreased GSIS underlie the pathogenesis of diabetes. Evidence from several laboratories, including our own, demonstrated requisite roles of Rac1 and phagocyte-like NADPH oxidase (Nox2)-derived reactive oxygen species (ROS) in optimal function of the pancreatic β-cell, including GSIS. However, it is becoming increasingly clear that prolonged exposure of β-cells to hyperglycemic conditions, leads to sustained activation of Rac1-Nox2 signaling axis culminating in excessive generation of intracellular ROS (oxidative stress) and β-cell dysregulation and demise. Such "cytotoxic" effects of ROS appear to be mediated via the stress-activated protein kinases/mitogen-activated protein kinases (SAPK/MAPK) signaling pathways. OBJECTIVE This review discusses our current understanding of regulation and functions of the conventional MAPKs, namely, ERK1/2, JNK1/2 and p38MAPK. CONCLUSION The MAPK pathways are activated in the presence of various stress stimuli including intracellular ROS, via distinct signaling cascades. Once activated, MAPKs participate in specific intracellular signaling processes via interaction with several downstream kinases including the MAPKactivated protein kinases (MAPKAPKs) and transcription factors including c-jun and p53. We have provided an overview of existing evidence in the islet β-cell on the regulatory roles of these MAPKs in mediating cellular responses to alterations in intracellularly generated ROS, which is mediated by the Rac1-Nox2 signaling module. Additionally, we enlisted recent patents developed to improve β-cell function in diabetes and novel pharmacological agents that target oxidative stress and MAPK pathways.
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Affiliation(s)
- Vaibhav Sidarala
- Beta-Cell Biochemistry Laboratory, John D. Dingell VA Medical Center, Department of Pharmaceutical Sciences, Wayne State University, Detroit, MI 48201. United States
| | - Anjaneyulu Kowluru
- B-4237 Research Service, John D. Dingell VA Medical Center, 4646 John R, Detroit, MI 48201. United States
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Leduc M, Richard J, Costes S, Muller D, Varrault A, Compan V, Mathieu J, Tanti JF, Pagès G, Pouyssegur J, Bertrand G, Dalle S, Ravier MA. ERK1 is dispensable for mouse pancreatic beta cell function but is necessary for glucose-induced full activation of MSK1 and CREB. Diabetologia 2017; 60:1999-2010. [PMID: 28721437 DOI: 10.1007/s00125-017-4356-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 06/02/2017] [Indexed: 11/24/2022]
Abstract
AIMS/HYPOTHESIS Insufficient insulin secretion from pancreatic beta cells, which is associated with a decrease in beta cell mass, is a characteristic of type 2 diabetes. Extracellular signal-related kinase 1 and 2 (ERK1/2) inhibition in beta cells has been reported to affect insulin secretion, gene transcription and survival, although whether ERK1 and ERK2 play distinct roles is unknown. The aim of this study was to assess the individual roles of ERK1 and ERK2 in beta cells using ERK1 (also known as Mapk3)-knockout mice (Erk1 -/- mice) and pharmacological approaches. METHODS NAD(P)H, free cytosolic Ca2+ concentration and insulin secretion were determined in islets. ERK1 and ERK2 subplasmalemmal translocation and activity was monitored using total internal reflection fluorescence microscopy. ERK1/2, mitogen and stress-activated kinase1 (MSK1) and cAMP-responsive element-binding protein (CREB) activation were evaluated by western blot and/or immunocytochemistry. The islet mass was determined from pancreatic sections. RESULTS Glucose induced rapid subplasmalemmal recruitment of ERK1 and ERK2. When both ERK1 and ERK2 were inhibited simultaneously, the rapid transient peak of the first phase of glucose-induced insulin secretion was reduced by 40% (p < 0.01), although ERK1 did not appear to be involved in this process. By contrast, ERK1 was required for glucose-induced full activation of several targets involved in beta cell survival; MSK1 and CREB were less active in Erk1 -/- mouse beta cells (p < 0.01) compared with Erk1 +/+ mouse beta cells, and their phosphorylation could only be restored when ERK1 was re-expressed and not when ERK2 was overexpressed. Finally, the islet mass of Erk1 -/- mice was slightly increased in young animals (4-month-old mice) vs Erk1 +/+ mice (section occupied by islets [mean ± SEM]: 0.74% ± 0.03% vs 0.62% ± 0.04%; p < 0.05), while older mice (10 months old) were less prone to age-associated pancreatic peri-insulitis (infiltrated islets [mean ± SEM]: 7.51% ± 1.34% vs 2.03% ± 0.51%; p < 0.001). CONCLUSIONS/INTERPRETATION ERK1 and ERK2 play specific roles in beta cells. ERK2 cannot always compensate for the lack of ERK1 but the absence of a clear-cut phenotype in Erk1 -/- mice shows that ERK1 is dispensable in normal conditions.
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Affiliation(s)
- Michele Leduc
- Institut de Génomique Fonctionnelle, Centre National de la Recherche Scientifique (CNRS), Inserm, Université de Montpellier, 141 Rue de la Cardonille, 34094, Montpellier CEDEX 5, France
| | - Joy Richard
- Institut de Génomique Fonctionnelle, Centre National de la Recherche Scientifique (CNRS), Inserm, Université de Montpellier, 141 Rue de la Cardonille, 34094, Montpellier CEDEX 5, France
| | - Safia Costes
- Institut de Génomique Fonctionnelle, Centre National de la Recherche Scientifique (CNRS), Inserm, Université de Montpellier, 141 Rue de la Cardonille, 34094, Montpellier CEDEX 5, France
| | - Dany Muller
- Institut de Génomique Fonctionnelle, Centre National de la Recherche Scientifique (CNRS), Inserm, Université de Montpellier, 141 Rue de la Cardonille, 34094, Montpellier CEDEX 5, France
| | - Annie Varrault
- Institut de Génomique Fonctionnelle, Centre National de la Recherche Scientifique (CNRS), Inserm, Université de Montpellier, 141 Rue de la Cardonille, 34094, Montpellier CEDEX 5, France
| | - Vincent Compan
- Institut de Génomique Fonctionnelle, Centre National de la Recherche Scientifique (CNRS), Inserm, Université de Montpellier, 141 Rue de la Cardonille, 34094, Montpellier CEDEX 5, France
| | - Julia Mathieu
- Institut de Génomique Fonctionnelle, Centre National de la Recherche Scientifique (CNRS), Inserm, Université de Montpellier, 141 Rue de la Cardonille, 34094, Montpellier CEDEX 5, France
| | - Jean-François Tanti
- Faculté de Médecine, Centre Méditerranéen de Médecine Moléculaire, Inserm U1065, Université de Nice Sophia Antipolis, Nice, France
| | - Gilles Pagès
- Institute for Research on Cancer and Aging, Nice (IRCAN), Centre Antoine Lacassagne, Université de Nice Sophia Antipolis, Nice, France
| | - Jacques Pouyssegur
- Institute for Research on Cancer and Aging, Nice (IRCAN), Centre Antoine Lacassagne, Université de Nice Sophia Antipolis, Nice, France
- Medical Biology Department, Centre Scientifique de Monaco (CSM), Monaco, Principality of Monaco
| | - Gyslaine Bertrand
- Institut de Génomique Fonctionnelle, Centre National de la Recherche Scientifique (CNRS), Inserm, Université de Montpellier, 141 Rue de la Cardonille, 34094, Montpellier CEDEX 5, France
| | - Stéphane Dalle
- Institut de Génomique Fonctionnelle, Centre National de la Recherche Scientifique (CNRS), Inserm, Université de Montpellier, 141 Rue de la Cardonille, 34094, Montpellier CEDEX 5, France
| | - Magalie A Ravier
- Institut de Génomique Fonctionnelle, Centre National de la Recherche Scientifique (CNRS), Inserm, Université de Montpellier, 141 Rue de la Cardonille, 34094, Montpellier CEDEX 5, France.
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23
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Niu B, Li C, Su H, Li Q, He Q, Liu L, Xue Y, Shen T, Xia X. Glucagon-like peptide-1 receptor agonist exendin-4 protects against interleukin-1β-mediated inhibition of glucose-stimulated insulin secretion by mouse insulinoma β cells. Exp Ther Med 2017; 14:2671-2676. [PMID: 28947919 DOI: 10.3892/etm.2017.4803] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2015] [Accepted: 11/04/2016] [Indexed: 01/01/2023] Open
Abstract
The aim of the present study was to investigate the protective effect of the glucagon-like peptide-1 receptor agonist exendin-4 on the interleukin (IL)-1β-induced impairment of glucose-stimulated insulin secretion (GSIS) in β-TC-6 cells. β-TC-6 cells were pretreated with various concentrations of IL-1β (0.15, 1.5 or 15 ng/ml) and exendin-4 (0.1 or 1 mM). Exendin-4 was administered to β-TC-6 cells prior to, during and following pretreatment. Cells were stimulated with various concentrations of glucose (0, 1.38, 5.5 and 11.1 mM), and insulin was measured via radioimmunoassay of the supernatant; furthermore, western blot analysis was used to detect phosphorylated extracellular receptor kinase (ERK)1/2. The insulin levels (151.08±14.34 µIU/ml) and ERK1/2 phosphorylation in β-TC-6 cells peaked in response to 1.38 mM glucose stimulation compared with 0, 5.5 and 11.1 mM glucose stimulation. IL-1β inhibited GSIS in a dose-dependent manner: Insulin levels were 83.76±1.16 µIU/ml when 0.15 ng/ml IL-1β was added under GSIS, 59.46±3.20 µIU/ml when 1.5 ng/ml IL-1β was added under GSIS, and 56.98±1.19 µIU/ml when 15 ng/ml IL-1β was added under GSIS. Exendin-4 exerted a protective effect against IL-1β-induced GSIS inhibition in a dose-dependent manner. The greatest protective effect was observed when exendin-4 was added prior to IL-1β pretreatment, which was statistically significant (P<0.05). These findings suggested that exendin-4 was able to reverse the IL-1β-induced inhibition of ERK1/2 phosphorylation and serves a protective role by impairing GSIS induced by IL-1β in β-TC-6 cells. This mechanism may be associated with the recovery of ERK1/2 activation.
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Affiliation(s)
- Ben Niu
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650500, P.R. China.,Department of Endocrinology, The Affiliated Hospital of Kunming University of Science and Technology, The First People's Hospital of Yunnan, Kunming, Yunnan 650032, P.R. China
| | - Chao Li
- Department of Emergency Medicine, The People's Hospital of Yuxi City, Yuxi, Yunnan 653100, P.R. China
| | - Heng Su
- Department of Endocrinology, The Affiliated Hospital of Kunming University of Science and Technology, The First People's Hospital of Yunnan, Kunming, Yunnan 650032, P.R. China
| | - Qingzhu Li
- Department of Endocrinology, The Affiliated Hospital of Kunming University of Science and Technology, The First People's Hospital of Yunnan, Kunming, Yunnan 650032, P.R. China
| | - Qiu He
- Department of Endocrinology, The Affiliated Hospital of Kunming University of Science and Technology, The First People's Hospital of Yunnan, Kunming, Yunnan 650032, P.R. China
| | - Lijuan Liu
- Department of Cadre Ward, WISCO General Hospital, Wuhan, Hubei 430080, P.R. China
| | - Yuanming Xue
- Department of Endocrinology, The Affiliated Hospital of Kunming University of Science and Technology, The First People's Hospital of Yunnan, Kunming, Yunnan 650032, P.R. China
| | - Tao Shen
- Institute of Basic and Clinical Medicine, Center of Clinical Molecular Biology of Yunnan, Affiliated Hospital of Kunming University of Science and Technology, First People's Hospital of Yunnan, Kunming, Yunnan 650032, P.R. China
| | - Xueshan Xia
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan 650500, P.R. China
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24
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Emery AC, Xu W, Eiden MV, Eiden LE. Guanine nucleotide exchange factor Epac2-dependent activation of the GTP-binding protein Rap2A mediates cAMP-dependent growth arrest in neuroendocrine cells. J Biol Chem 2017; 292:12220-12231. [PMID: 28546426 DOI: 10.1074/jbc.m117.790329] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 05/23/2017] [Indexed: 11/06/2022] Open
Abstract
First messenger-dependent activation of MAP kinases in neuronal and endocrine cells is critical for cell differentiation and function and requires guanine nucleotide exchange factor (GEF)-mediated activation of downstream Ras family small GTPases, which ultimately lead to ERK, JNK, and p38 phosphorylation. Because there are numerous GEFs and also a host of Ras family small GTPases, it is important to know which specific GEF-small GTPase dyad functions in a given cellular process. Here we investigated the upstream activators and downstream effectors of signaling via the GEF Epac2 in the neuroendocrine NS-1 cell line. Three cAMP sensors, Epac2, PKA, and neuritogenic cAMP sensor-Rapgef2, mediate distinct cellular outputs: p38-dependent growth arrest, cAMP response element-binding protein-dependent cell survival, and ERK-dependent neuritogenesis, respectively, in these cells. Previously, we found that cAMP-induced growth arrest of PC12 and NS-1 cells requires Epac2-dependent activation of p38 MAP kinase, which posed the important question of how Epac2 engages p38 without simultaneously activating other MAP kinases in neuronal and endocrine cells. We now show that the small GTP-binding protein Rap2A is the obligate effector for, and GEF substrate of, Epac2 in mediating growth arrest through p38 activation in NS-1 cells. This new pathway is distinctly parcellated from the G protein-coupled receptor → Gs → adenylate cyclase → cAMP → PKA → cAMP response element-binding protein pathway mediating cell survival and the G protein-coupled receptor → Gs → adenylate cyclase → cAMP → neuritogenic cAMP sensor-Rapgef2 → B-Raf → MEK → ERK pathway mediating neuritogenesis in NS-1 cells.
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Affiliation(s)
- Andrew C Emery
- Section on Molecular Neuroscience, National Institute of Mental Health Intramural Research Program, Bethesda, Maryland 20892
| | - Wenqin Xu
- Section on Molecular Neuroscience, National Institute of Mental Health Intramural Research Program, Bethesda, Maryland 20892
| | - Maribeth V Eiden
- Office of the Scientific Director, National Institute of Mental Health Intramural Research Program, Bethesda, Maryland 20892
| | - Lee E Eiden
- Section on Molecular Neuroscience, National Institute of Mental Health Intramural Research Program, Bethesda, Maryland 20892.
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25
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Niu B, Su H, Xia XS, He Q, Xue YM, Yan XM. The role of interleukin-1β and extracellular signal-regulated kinase 1/2 in glucose-stimulated insulin secretion. Kaohsiung J Med Sci 2017; 33:224-228. [DOI: 10.1016/j.kjms.2017.02.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Revised: 01/28/2017] [Accepted: 02/13/2017] [Indexed: 01/17/2023] Open
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26
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Skrzypski M, Billert M, Mergler S, Khajavi N, Nowak KW, Strowski MZ. Role of TRPV channels in regulating various pancreatic β-cell functions: Lessons from in vitro studies. Biosci Trends 2017; 11:9-15. [PMID: 28154245 DOI: 10.5582/bst.2016.01226] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Pancreatic β-cell functions are regulated by a variety of endogenous and exogenous factors. Calcium is one of the most potent triggers of β-cell growth, insulin production and exocytosis. Recently, others and we showed that TRPV channels are expressed in insulin producing cell lines and/or primary β-cells. These channels modulate calcium ions, insulin secretion and cell proliferation. Besides the classical roles of TRPV channels in the sensory system, there are also novel functions described in non-excitable cells such as in insulin-producing β-cells. This review summarises the current knowledge about the expression and the role of TRPV channels in controlling β-cell functions based upon studies performed in isolated primary β-cells as well as permanent β-cell models.
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Affiliation(s)
- Marek Skrzypski
- Department of Animal Physiology and Biochemistry, Poznań University of Life Sciences
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27
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Niu B, Liu L, Su H, Xia X, He Q, Feng Y, Xue Y, Yan X. Role of extracellular signal‑regulated kinase 1/2 signal transduction pathway in insulin secretion by β‑TC6 cells. Mol Med Rep 2016; 13:4451-4. [PMID: 27035884 DOI: 10.3892/mmr.2016.5053] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2015] [Accepted: 02/29/2016] [Indexed: 11/06/2022] Open
Abstract
The present study aimed to investigate the role of the extracellular signal-regulated kinase (ERK)1/2 signal transduction pathway in glucose‑stimulated insulin secretion in β‑TC6 mouse pancreatic cells. Insulin production by β‑TC6 cells was stimulated with various concentrations of glucose, which was dose-dependently inhibited by mitogen‑activated protein kinase inhibitor PD98059, as indicated by a radioimmunoassay. Furthermore, glucose stimulation enhanced the phosphorylation of ERK1/2, which was dose-dependently inhibited by PD98059, as indicated by western blot analysis. These results indicated that the activation of the ERK1/2 signal transduction pathway may have an important role in glucose‑stimulated insulin secretion in β‑TC6 cells.
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Affiliation(s)
- Ben Niu
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan 650500, P.R. China
| | - Lijuan Liu
- Department of Cadre Ward, WISCO General Hospital, Wuhan, Hubei 430080, P.R. China
| | - Heng Su
- Department of Endocrinology, The Affiliated Hospital of Kunming University of Science and Technology, The First People's Hospital of Yunnan, Kunming, Yunnan 650032, P.R. China
| | - Xueshan Xia
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan 650500, P.R. China
| | - Qiu He
- Department of Endocrinology, The Affiliated Hospital of Kunming University of Science and Technology, The First People's Hospital of Yunnan, Kunming, Yunnan 650032, P.R. China
| | - Yue Feng
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan 650500, P.R. China
| | - Yuanming Xue
- Department of Endocrinology, The Affiliated Hospital of Kunming University of Science and Technology, The First People's Hospital of Yunnan, Kunming, Yunnan 650032, P.R. China
| | - Xinming Yan
- Institute of Basic and Clinical Medicine, Center of Clinical Molecular Biology of Yunnan, The Affiliated Hospital of Kunming University of Science and Technology, The First People's Hospital of Yunnan, Kunming, Yunnan 650032, P.R. China
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28
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Pratt EPS, Salyer AE, Guerra ML, Hockerman GH. Ca2+ influx through L-type Ca2+ channels and Ca2+-induced Ca2+ release regulate cAMP accumulation and Epac1-dependent ERK 1/2 activation in INS-1 cells. Mol Cell Endocrinol 2016; 419:60-71. [PMID: 26435461 PMCID: PMC4684454 DOI: 10.1016/j.mce.2015.09.034] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 08/28/2015] [Accepted: 09/29/2015] [Indexed: 02/09/2023]
Abstract
We previously reported that INS-1 cells expressing the intracellular II-III loop of the L-type Ca(2+) channel Cav1.2 (Cav1.2/II-III cells) are deficient in Ca(2+)-induced Ca(2+) release (CICR). Here we show that glucose-stimulated ERK 1/2 phosphorylation (GSEP) is slowed and reduced in Cav1.2/II-III cells compared to INS-1 cells. This parallels a decrease in glucose-stimulated cAMP accumulation (GS-cAMP) in Cav1.2/II-III cells. Influx of Ca(2+) via L-type Ca(2+) channels and CICR play roles in both GSEP and GS-cAMP in INS-1 cells since both are inhibited by nicardipine or ryanodine. Further, the Epac1-selective inhibitor CE3F4 abolishes glucose-stimulated ERK activation in INS-1 cells, as measured using the FRET-based sensor EKAR. The non-selective Epac antagonist ESI-09 but not the Epac2-selective antagonist ESI-05 nor the PKA antagonist Rp-cAMPs inhibits GSEP in both INS-1 and Cav1.2/II-III cells. We conclude that L-type Ca(2+) channel-dependent cAMP accumulation, that's amplified by CICR, activates Epac1 and drives GSEP in INS-1 cells.
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Affiliation(s)
- Evan P S Pratt
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA; Purdue University Life Sciences Graduate Program, Purdue University, West Lafayette, IN, USA
| | - Amy E Salyer
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA
| | - Marcy L Guerra
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA
| | - Gregory H Hockerman
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA.
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Islet Neogenesis Associated Protein (INGAP) induces the differentiation of an adult human pancreatic ductal cell line into insulin-expressing cells through stepwise activation of key transcription factors for embryonic beta cell development. Differentiation 2015; 90:77-90. [DOI: 10.1016/j.diff.2015.10.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 10/13/2015] [Accepted: 10/22/2015] [Indexed: 01/13/2023]
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30
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Ning SL, Zheng WS, Su J, Liang N, Li H, Zhang DL, Liu CH, Dong JH, Zhang ZK, Cui M, Hu QX, Chen CC, Liu CH, Wang C, Pang Q, Chen YX, Yu X, Sun JP. Different downstream signalling of CCK1 receptors regulates distinct functions of CCK in pancreatic beta cells. Br J Pharmacol 2015; 172:5050-67. [PMID: 26248680 DOI: 10.1111/bph.13271] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Revised: 07/18/2015] [Accepted: 07/26/2015] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND AND PURPOSE Cholecystokinin (CCK) is secreted by intestinal I cells and regulates important metabolic functions. In pancreatic islets, CCK controls beta cell functions primarily through CCK1 receptors, but the signalling pathways downstream of these receptors in pancreatic beta cells are not well defined. EXPERIMENTAL APPROACH Apoptosis in pancreatic beta cell apoptosis was evaluated using Hoechst-33342 staining, TUNEL assays and Annexin-V-FITC/PI staining. Insulin secretion and second messenger production were monitored using ELISAs. Protein and phospho-protein levels were determined by Western blotting. A glucose tolerance test was carried out to examine the functions of CCK-8s in streptozotocin-induced diabetic mice. KEY RESULTS The sulfated carboxy-terminal octapeptide CCK26-33 amide (CCK-8s) activated CCK1 receptors and induced accumulation of both IP3 and cAMP. Whereas Gq -PLC-IP3 signalling was required for the CCK-8s-induced insulin secretion under low-glucose conditions, Gs -PKA/Epac signalling contributed more strongly to the CCK-8s-mediated insulin secretion in high-glucose conditions. CCK-8s also promoted formation of the CCK1 receptor/β-arrestin-1 complex in pancreatic beta cells. Using β-arrestin-1 knockout mice, we demonstrated that β-arrestin-1 is a key mediator of both CCK-8s-mediated insulin secretion and of its the protective effect against apoptosis in pancreatic beta cells. The anti-apoptotic effects of β-arrestin-1 occurred through cytoplasmic late-phase ERK activation, which activates the 90-kDa ribosomal S6 kinase-phospho-Bcl-2-family protein pathway. CONCLUSIONS AND IMPLICATIONS Knowledge of different CCK1 receptor-activated downstream signalling pathways in the regulation of distinct functions of pancreatic beta cells could be used to identify biased CCK1 receptor ligands for the development of new anti-diabetic drugs.
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Affiliation(s)
- Shang-lei Ning
- Department of Biochemistry and Molecular Biology and Key Laboratory Experimental Teratology of the Ministry of Education, Jinan, Shandong, China.,Qilu Hospital, Shandong University, Jinan, Shandong, China.,Department of Biochemistry and Molecular Biology, Shandong University School of Medicine, Jinan, Shandong, China
| | - Wen-shuai Zheng
- Shandong Provincial School Key laboratory for Protein Science of Chronic degenerative diseases, Jinan, Shandong, China.,Department of Physiology, Shandong University School of Medicine, Jinan, Shandong, China
| | - Jing Su
- Shandong Provincial School Key laboratory for Protein Science of Chronic degenerative diseases, Jinan, Shandong, China.,Department of Physiology, Shandong University School of Medicine, Jinan, Shandong, China
| | - Nan Liang
- Department of Biochemistry and Molecular Biology and Key Laboratory Experimental Teratology of the Ministry of Education, Jinan, Shandong, China.,Department of Biochemistry and Molecular Biology, Shandong University School of Medicine, Jinan, Shandong, China
| | - Hui Li
- Shandong Provincial School Key laboratory for Protein Science of Chronic degenerative diseases, Jinan, Shandong, China.,Department of Physiology, Shandong University School of Medicine, Jinan, Shandong, China
| | - Dao-lai Zhang
- Department of Biochemistry and Molecular Biology and Key Laboratory Experimental Teratology of the Ministry of Education, Jinan, Shandong, China.,Shandong Provincial School Key laboratory for Protein Science of Chronic degenerative diseases, Jinan, Shandong, China
| | - Chun-hua Liu
- Shandong Provincial School Key laboratory for Protein Science of Chronic degenerative diseases, Jinan, Shandong, China.,Department of Physiology, Shandong University School of Medicine, Jinan, Shandong, China
| | - Jun-hong Dong
- Department of Biochemistry and Molecular Biology and Key Laboratory Experimental Teratology of the Ministry of Education, Jinan, Shandong, China.,Department of Physiology, Shandong University School of Medicine, Jinan, Shandong, China
| | - Zheng-kui Zhang
- Department of Physiology, Shandong University School of Medicine, Jinan, Shandong, China
| | - Min Cui
- Department of Physiology, Shandong University School of Medicine, Jinan, Shandong, China
| | - Qiao-Xia Hu
- Department of Biochemistry and Molecular Biology and Key Laboratory Experimental Teratology of the Ministry of Education, Jinan, Shandong, China.,Department of Biochemistry and Molecular Biology, Shandong University School of Medicine, Jinan, Shandong, China
| | - Chao-chao Chen
- Shandong Provincial School Key laboratory for Protein Science of Chronic degenerative diseases, Jinan, Shandong, China.,Department of Physiology, Shandong University School of Medicine, Jinan, Shandong, China
| | - Chang-hong Liu
- Shandong Provincial Qianfoshan, Shandong University, Jinan, Shandong, China
| | - Chuan Wang
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, Hebei, China
| | - Qi Pang
- Shandong Provincial Hospital, Shandong University, Jinan, Shandong, China
| | - Yu-xin Chen
- Qilu Hospital, Shandong University, Jinan, Shandong, China
| | - Xiao Yu
- Department of Biochemistry and Molecular Biology and Key Laboratory Experimental Teratology of the Ministry of Education, Jinan, Shandong, China.,Qilu Hospital, Shandong University, Jinan, Shandong, China.,Shandong Provincial School Key laboratory for Protein Science of Chronic degenerative diseases, Jinan, Shandong, China.,Department of Physiology, Shandong University School of Medicine, Jinan, Shandong, China
| | - Jin-peng Sun
- Department of Biochemistry and Molecular Biology and Key Laboratory Experimental Teratology of the Ministry of Education, Jinan, Shandong, China.,Shandong Provincial School Key laboratory for Protein Science of Chronic degenerative diseases, Jinan, Shandong, China.,Department of Biochemistry and Molecular Biology, Shandong University School of Medicine, Jinan, Shandong, China.,Shandong Provincial Hospital, Shandong University, Jinan, Shandong, China
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SALVATIERRA CRISTIANAS, REIS SÍLVIAR, PESSOA ANAF, SOUZA LETÍCIAMDE, STOPPIGLIA LUIZF, VELOSO ROBERTOV, REIS MARISEA, CARNEIRO EVERARDOM, BOSCHERO ANTONIOC, COLODEL EDSONM, ARANTES VANESSAC, LATORRACA MÁRCIAQ. Short-term low-protein diet during pregnancy alters islet area and protein content of phosphatidylinositol 3-kinase pathway in rats. ACTA ACUST UNITED AC 2015; 87:1007-18. [DOI: 10.1590/0001-3765201520140251] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Accepted: 12/15/2014] [Indexed: 12/31/2022]
Abstract
The phosphatidylinositol 3-kinase and mitogen-activated protein kinase pathways mediate β cell growth, proliferation, survival and death. We investigated whether protein restriction during pregnancy alters islet morphometry or the expression and phosphorylation of several proteins involved in the phosphatidylinositol 3-kinase and mitogen-activated protein kinase pathways. As controls, adult pregnant and non-pregnant rats were fed a normal-protein diet (17%). Pregnant and non-pregnant rats in the experimental groups were fed a low-protein diet (6%) for 15 days. Low protein diet during pregnancy increased serum prolactin level, reduced serum corticosterone concentration and the expression of both protein kinase B/AKT1 (AKT1) and p70 ribosomal protein S6 kinase (p70S6K), as well as the islets area, but did not alter the insulin content of pancreatic islets. Pregnancy increased the expression of the Src homology/collagen (SHC) protein and the extracellular signal-regulated kinases 1/2 (ERK1/2) independent of diet. ERK1/2 phosphorylation (pERK1/2) was similar in islets from pregnant and non-pregnant rats fed a low-protein diet, and was higher in islets from pregnant rats than in islets from non-pregnant rats fed a normal-protein diet. Thus, a short-term, low-protein diet during pregnancy was sufficient to reduce the levels of proteins in the phosphatidylinositol 3-kinase pathway and affect islet morphometry.
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Manyes L, Arribas M, Gomez C, Calzada N, Fernandez-Medarde A, Santos E. Transcriptional profiling reveals functional links between RasGrf1 and Pttg1 in pancreatic beta cells. BMC Genomics 2014; 15:1019. [PMID: 25421944 PMCID: PMC4301450 DOI: 10.1186/1471-2164-15-1019] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Accepted: 11/06/2014] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Our prior characterization of RasGrf1 deficient mice uncovered significant defects in pancreatic islet count and size as well as beta cell development and signaling function, raising question about the mechanisms linking RasGrf1 to the generation of those "pancreatic" phenotypes. RESULTS Here, we compared the transcriptional profile of highly purified pancreatic islets from RasGrf1 KO mice to that of WT control animals using commercial oligonucleotide microarrays. RasGrf1 elimination resulted in differential gene expression of numerous components of MAPK- and Calcium-signaling pathways, suggesting a relevant contribution of this GEF to modulation of cellular signaling in the cell lineages integrating the pancreatic islets. Whereas the overall transcriptional profile of pancreatic islets was highly specific in comparison to other organs of the same KO mice, a significant specific repression of Pttg1 was a common transcriptional alteration shared with other tissues of neuroectodermal origin. This observation, together with the remarkable pancreatic phenotypic similarities between RasGrf1 KO and Pttg1 KO mice suggested the possibility of proximal functional regulatory links between RasGrf1 and Pttg1 in pancreatic cell lineages expressing these proteins.Analysis of the mPttg1 promoter region identified specific recognition sites for numerous transcription factors which were also found to be differentially expressed in RasGrf1 KO pancreatic islets and are known to be relevant for Ras-ERK signaling as well as beta cell function. Reporter luciferase assays in BT3 insulinoma cells demonstrated the ability of RasGrf1 to modulate mPttg1 promoter activity through ERK-mediated signals. Analysis of the phenotypic interplay between RasGrf1 and Pttg1 in double knockout RasGrf1/Pttg1 mice showed that combined elimination of the two loci resulted in dramatically reduced values of islet and beta cell count and glucose homeostasis function which neared those measured in single Pttg1 KO mice and were significantly lower than those observed in individual RasGrf1 KO mice. CONCLUSIONS The specific transcriptional profile and signaling behavior of RasgGrf1 KO pancreatic islets, together with the dominance of Pttg1 over RasGrf1 with regards to the generation of these phenotypes in mouse pancreas, suggest that RasGrf1 is an important upstream component of signal transduction pathways regulating Pttg1 expression and controlling beta cell development and physiological responses.
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Affiliation(s)
| | | | | | | | - Alberto Fernandez-Medarde
- Centro de Investigación del Cáncer, IBMCC (CSIC-USAL), University of Salamanca, Campus Unamuno, 37007 Salamanca, Spain.
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Li Y, Guo Y, Tang J, Jiang J, Chen Z. New insights into the roles of CHOP-induced apoptosis in ER stress. Acta Biochim Biophys Sin (Shanghai) 2014; 46:629-40. [PMID: 25016584 DOI: 10.1093/abbs/gmu048] [Citation(s) in RCA: 319] [Impact Index Per Article: 31.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Endoplasmic reticulum stress (ER stress) is triggered due to a loss of homeostasis in the ER, resulting in accumulation of misfolded proteins in the ER lumen. ER stress activates a series of adaptive mechanisms known as the unfolded protein response. Perturbation of the ER is a powerful inducer of the transcription factor C/EBP homologous protein (CHOP). Although it has been proved that excessive or adverse stress to the ER triggers apoptosis, the specific mechanisms underlying these processes induced by CHOP remain unclear. By now, CHOP-induced apoptosis in ER stress has been implicated in numerous human diseases, such as neurodegenerative diseases, diabetes, ischemic diseases, tumor, and so on. In this review, we summarized the current understanding of the roles of CHOP in the development of several diseases from the laboratory to the clinic.
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Luo Y, He F, Hu L, Hai L, Huang M, Xu Z, Zhang J, Zhou Z, Liu F, Dai YS. Transcription factor Ets1 regulates expression of thioredoxin-interacting protein and inhibits insulin secretion in pancreatic β-cells. PLoS One 2014; 9:e99049. [PMID: 24897113 PMCID: PMC4045976 DOI: 10.1371/journal.pone.0099049] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Accepted: 05/08/2014] [Indexed: 11/18/2022] Open
Abstract
Long-term activation of extracellular-regulated kinase (ERK1/2) pathway has been shown to cause glucotoxicity and inhibit insulin gene expression in β-cells. Transcription factor Ets1 is activated by ERK1/2-mediated phosphorylation at the Thr38 residue. We hypothesize that Ets1 plays an important role in mediating ERK1/2 induced glucotoxicity in β-cells. We determined the role of Ets1 in Min6 cells and isolated mouse islets using overexpression and siRNA mediated knockdown of Ets1. The results show that Ets1 was localized in insulin-staining positive cells but not in glucagon-staining positive cells. Overexpression of Ets1 reduced glucose-stimulated insulin secretion in primary mouse islets. Overexpression of Ets1 in Min6 β-cells and mouse islets increased expression of thioredoxin-interacting protein (TXNIP). Conversely, knockdown of Ets1 by siRNA reduced expression of TXNIP in Min6 cells. Ets1 was associated with the txnip promoter in min6 cells and transfection of 293 cells with Ets1 and p300 synergistically increased txnip promoter reporter activity. Moreover, overexpression of Ets1 inhibited Min6 cell proliferation. Our results suggest that Ets1, by promoting TXNIP expression, negatively regulates β-cell function. Thus, over-activation of Ets1 may contribute to diet-induced β-cell dysfunction.
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Affiliation(s)
- Yan Luo
- Metabolic Syndrome Research Center, Key Laboratory of Diabetes Immunology, Ministry of Education, the Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Fengli He
- Metabolic Syndrome Research Center, Key Laboratory of Diabetes Immunology, Ministry of Education, the Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Li Hu
- Metabolic Syndrome Research Center, Key Laboratory of Diabetes Immunology, Ministry of Education, the Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Luo Hai
- Metabolic Syndrome Research Center, Key Laboratory of Diabetes Immunology, Ministry of Education, the Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Meifeng Huang
- Metabolic Syndrome Research Center, Key Laboratory of Diabetes Immunology, Ministry of Education, the Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Zhipeng Xu
- Metabolic Syndrome Research Center, Key Laboratory of Diabetes Immunology, Ministry of Education, the Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Jingjing Zhang
- Metabolic Syndrome Research Center, Key Laboratory of Diabetes Immunology, Ministry of Education, the Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Zhiguang Zhou
- Metabolic Syndrome Research Center, Key Laboratory of Diabetes Immunology, Ministry of Education, the Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Feng Liu
- Metabolic Syndrome Research Center, Key Laboratory of Diabetes Immunology, Ministry of Education, the Second Xiangya Hospital, Central South University, Changsha, Hunan, China
- Department of Pharmacology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Yan-Shan Dai
- Metabolic Syndrome Research Center, Key Laboratory of Diabetes Immunology, Ministry of Education, the Second Xiangya Hospital, Central South University, Changsha, Hunan, China
- * E-mail:
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Riopel M, Stuart W, Wang R. Fibrin improves beta (INS-1) cell function, proliferation and survival through integrin αvβ3. Acta Biomater 2013; 9:8140-8. [PMID: 23747317 DOI: 10.1016/j.actbio.2013.05.035] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Revised: 05/06/2013] [Accepted: 05/30/2013] [Indexed: 12/30/2022]
Abstract
Extracellular matrix (ECM)-integrin stimulation can promote beta cell differentiation, proliferation and function. However, beta cells lose their insulin secretion function in response to glucose stimulation, and senesce when cultured with ECM proteins for a long time. Fibrin is a provisional ECM protein that is capable of maintaining beta cell function, yet the mechanisms by which this occurs is unknown. The present study examined how fibrin interacts with integrin receptors to promote beta cell cluster formation, proliferation and function. The rat insulinoma cell line, INS-1, was cultured on tissue-culture polystyrene, or with 2-D or 3-D fibrin gels for up to 4 weeks. Cells cultured with fibrin formed islet-like clusters and showed direct contacts with fibrin determined by scanning electron microscopy. Fibrin-cultured INS-1 cells also had significantly increased glucose-stimulated insulin secretion. A significant increase in integrin αvβ3 protein and phosphorylated FAK, Erk1/2 and Akt levels was observed in fibrin-cultured INS-1 cells, which was associated with significantly increased cell proliferation and decreased cell apoptosis. Integrin αvβ3 blockade affected INS-1 cell spreading on fibrin gels, and resulted in significantly decreased FAK phosphorylation and increased cleaved caspase-3 levels. These results show that fibrin promotes beta cell function, proliferation and survival via integrin αvβ3 interactions.
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Wauson EM, Guerra ML, Barylko B, Albanesi JP, Cobb MH. Off-target effects of MEK inhibitors. Biochemistry 2013; 52:5164-6. [PMID: 23848362 DOI: 10.1021/bi4007644] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The mitogen-activated protein kinases (MAPKs) ERK1/2 regulate numerous cellular processes, including gene transcription, proliferation, and differentiation. The only known substrates of the MAP2Ks MEK1/2 are ERK1/2; thus, MEK inhibitors PD98059, U0126, and PD0325901 have been important tools in determining the functions of ERK1/2. By using these inhibitors and genetically manipulating MEK, we found that ERK1/2 activation is neither sufficient nor necessary for regulated secretion of insulin from pancreatic β cells or secretion of epinephrine from chromaffin cells. We show that both PD98059 and U0126 reduce agonist-induced entry of calcium into cells in a manner independent of their ability to inhibit ERK1/2. Caution should be used when interpreting results from experiments using these compounds.
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Affiliation(s)
- Eric M Wauson
- Department of Pharmacology, University of Texas Southwestern Medical Center , Dallas, Texas 75390-9041, United States
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Flores-López LA, Díaz-Flores M, García-Macedo R, Ávalos-Rodríguez A, Vergara-Onofre M, Cruz M, Contreras-Ramos A, Konigsberg M, Ortega-Camarillo C. High glucose induces mitochondrial p53 phosphorylation by p38 MAPK in pancreatic RINm5F cells. Mol Biol Rep 2013; 40:4947-58. [PMID: 23657598 DOI: 10.1007/s11033-013-2595-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Accepted: 04/29/2013] [Indexed: 01/09/2023]
Abstract
Pancreatic β-cell death in type 2 diabetes has been related to p53 subcellular localisation and phosphorylation. However, the mechanisms by which p53 is phosphorylated and its activation in response to oxidative stress remain poorly understood. Therefore, the aim of this study was to investigate mitochondrial p53 phosphorylation, its subcellular localisation and its relationship with apoptotic induction in RINm5F cells cultured under high glucose conditions. Our results show that p53 phosphorylation in the mitochondrial fraction was greater at ser392 than at ser15. This increased phosphorylation correlated with an increase in reactive oxygen species, a decrease in the Bcl-2/Bax ratio, a release of cytochrome c and an increase in the rate of apoptosis. We also observed a decline in ERK 1/2 phosphorylation over time, which is an indicator of cell proliferation. To identify the kinase responsible for phosphorylating p53, p38 mitogen-activated protein kinase (MAPK) activation was analysed. We found that high glucose induced an increase in p38 MAPK phosphorylation in the mitochondria after 24-72 h. Moreover, the phosphorylation of p53 (ser392) by p38 MAPK in mitochondria was confirmed by colocalisation studies with confocal microscopy. The addition of a specific p38 MAPK inhibitor (SB203580) to the culture medium during high glucose treatment blocked p53 mobilisation to the mitochondria and phosphorylation; thus, the release of cytochrome c and the apoptosis rate in RINm5F cells decreased. These results suggest that mitochondrial p53 phosphorylation by p38 MAPK plays an important role in RINm5F cell death under high glucose conditions.
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Affiliation(s)
- Luis A Flores-López
- Unidad de Investigación Médica en Bioquímica, HE, Centro Médico Nacional Siglo XXI. IMSS., Av. Cuauhtémoc 330, Col Doctores, Del. Cuauhtémoc, México, DF, Mexico
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Jain S, Ruiz de Azua I, Lu H, White MF, Guettier JM, Wess J. Chronic activation of a designer G(q)-coupled receptor improves β cell function. J Clin Invest 2013; 123:1750-62. [PMID: 23478411 DOI: 10.1172/jci66432] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Accepted: 01/17/2013] [Indexed: 12/12/2022] Open
Abstract
Type 2 diabetes (T2D) has emerged as a major threat to human health in most parts of the world. Therapeutic strategies aimed at improving pancreatic β cell function are predicted to prove beneficial for the treatment of T2D. In the present study, we demonstrate that drug-mediated, chronic, and selective activation of β cell G(q) signaling greatly improve β cell function and glucose homeostasis in mice. These beneficial metabolic effects were accompanied by the enhanced expression of many genes critical for β cell function, maintenance, and differentiation. By employing a combination of in vivo and in vitro approaches, we identified a novel β cell pathway through which receptor-activated G(q) leads to the sequential activation of ERK1/2 and IRS2 signaling, thus triggering a series of events that greatly improve β cell function. Importantly, we found that chronic stimulation of a designer G(q)-coupled receptor selectively expressed in β cells prevented both streptozotocin-induced diabetes and the metabolic deficits associated with the consumption of a high-fat diet in mice. Since β cells are endowed with numerous receptors that mediate their cellular effects via activation of G(q)-type G proteins, our findings provide a rational basis for the development of novel antidiabetic drugs targeting this class of receptors.
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Affiliation(s)
- Shalini Jain
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892, USA
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Orime K, Shirakawa J, Togashi Y, Tajima K, Inoue H, Ito Y, Sato K, Nakamura A, Aoki K, Goshima Y, Terauchi Y. Trefoil factor 2 promotes cell proliferation in pancreatic β-cells through CXCR-4-mediated ERK1/2 phosphorylation. Endocrinology 2013. [PMID: 23183167 DOI: 10.1210/en.2012-1814] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Decreased β-cell mass is a hallmark of type 2 diabetes, and therapeutic approaches to increase the pancreatic β-cell mass have been expected. In recent years, gastrointestinal incretin peptides have been shown to exert a cell-proliferative effect in pancreatic β-cells. Trefoil factor 2 (TFF2), which is predominantly expressed in the surface epithelium of the stomach, plays a role in antiapoptosis, migration, and proliferation. The TFF family is expressed in pancreatic β-cells, whereas the role of TFF2 in pancreatic β-cells has been obscure. In this study, we investigated the mechanism by which TFF2 enhances pancreatic β-cell proliferation. The effects of TFF2 on cell proliferation were evaluated in INS-1 cells, MIN6 cells, and mouse islets using an adenovirus vector containing TFF2 or a recombinant TFF2 peptide. The forced expression of TFF2 led to an increase in bromodeoxyuridine (BrdU) incorporation in both INS-1 cells and islets, without any alteration in insulin secretion. TFF2 significantly increased the mRNA expression of cyclin A2, D1, D2, D3, and E1 in islets. TFF2 peptide increased ERK1/2 phosphorylation and BrdU incorporation in MIN6 cells. A MAPK kinase inhibitor (U0126) abrogated the TFF2 peptide-mediated proliferation of MIN6 cells. A CX-chemokine receptor-4 antagonist also prevented the TFF2 peptide-mediated increase in ERK1/2 phosphorylation and BrdU incorporation in MIN6 cells. These results indicated that TFF2 is involved in β-cell proliferation at least partially via CX-chemokine receptor-4-mediated ERK1/2 phosphorylation, suggesting TFF2 may be a novel target for inducing β-cell proliferation.
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Affiliation(s)
- Kazuki Orime
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama-City University, 3-9 Fuku-ura, Kanazawa-ku, Yokohama 236-0004, Japan
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Selway JL, Moore CE, Mistry R, John Challiss RA, Herbert TP. Molecular mechanisms of muscarinic acetylcholine receptor-stimulated increase in cytosolic free Ca(2+) concentration and ERK1/2 activation in the MIN6 pancreatic β-cell line. Acta Diabetol 2012; 49:277-89. [PMID: 21833779 PMCID: PMC3407357 DOI: 10.1007/s00592-011-0314-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Accepted: 07/17/2011] [Indexed: 11/29/2022]
Abstract
Muscarinic acetylcholine receptor (mAChR) activation of pancreatic β-cells elevates intracellular Ca(2+) and potentiates glucose-stimulated insulin secretion. In addition, it activates a number of signaling molecules, including ERK1/2, whose activation has been shown to play an important role in regulating pancreatic β-cell function and mass. The aim of this work was to determine how mAChR activation elevates intracellular Ca(2+) concentration ([Ca(2+)]( i )) and activates ERK1/2 in the pancreatic β-cell line MIN6. We demonstrate that agonist-stimulated ERK1/2 activation is dependent on the activation of phospholipase C and an elevation in [Ca(2+)]( i ), but is independent of the activation of diacylglycerol-dependent protein kinase C isoenzymes. Using a pharmacological approach, we provide evidence that agonist-induced increases in [Ca(2+)]( i ) and ERK activity require (1) IP(3) receptor-mediated mobilization of Ca(2+) from the endoplasmic reticulum, (2) influx of extracellular Ca(2+) through store-operated channels, (3) closure of K(ATP) channels, and (4) Ca(2+) entry via L-type voltage-operated Ca(2+) channels. Moreover, this Ca(2+)-dependent activation of ERK is mediated via both Ras-dependent and Ras-independent mechanisms. In summary, this study provides important insights into the multifactorial signaling mechanisms linking mAChR activation to increases in [Ca(2+)]( i ) and ERK activity.
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Affiliation(s)
- Joanne L. Selway
- Department of Cell Physiology and Pharmacology, University of Leicester, Henry Wellcome Building, Leicester, LE1 9HN UK
| | - Claire E. Moore
- Department of Cell Physiology and Pharmacology, University of Leicester, Henry Wellcome Building, Leicester, LE1 9HN UK
| | - Rajendra Mistry
- Department of Cell Physiology and Pharmacology, University of Leicester, Henry Wellcome Building, Leicester, LE1 9HN UK
| | - R. A. John Challiss
- Department of Cell Physiology and Pharmacology, University of Leicester, Henry Wellcome Building, Leicester, LE1 9HN UK
| | - Terence P. Herbert
- Department of Cell Physiology and Pharmacology, University of Leicester, Henry Wellcome Building, Leicester, LE1 9HN UK
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Neuronal Cbl controls biosynthesis of insulin-like peptides in Drosophila melanogaster. Mol Cell Biol 2012; 32:3610-23. [PMID: 22778134 DOI: 10.1128/mcb.00592-12] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Cbl family proteins function as both E3 ubiquitin ligases and adaptor proteins to regulate various cellular signaling events, including the insulin/insulin-like growth factor 1 (IGF1) and epidermal growth factor (EGF) pathways. These pathways play essential roles in growth, development, metabolism, and survival. Here we show that in Drosophila melanogaster, Drosophila Cbl (dCbl) regulates longevity and carbohydrate metabolism through downregulating the production of Drosophila insulin-like peptides (dILPs) in the brain. We found that dCbl was highly expressed in the brain and knockdown of the expression of dCbl specifically in neurons by RNA interference increased sensitivity to oxidative stress or starvation, decreased carbohydrate levels, and shortened life span. Insulin-producing neuron-specific knockdown of dCbl resulted in similar phenotypes. dCbl deficiency in either the brain or insulin-producing cells upregulated the expression of dilp genes, resulting in elevated activation of the dILP pathway, including phosphorylation of Drosophila Akt and Drosophila extracellular signal-regulated kinase (dERK). Genetic interaction analyses revealed that blocking Drosophila epidermal growth factor receptor (dEGFR)-dERK signaling in pan-neurons or insulin-producing cells by overexpressing a dominant-negative form of dEGFR abolished the effect of dCbl deficiency on the upregulation of dilp genes. Furthermore, knockdown of c-Cbl in INS-1 cells, a rat β-cell line, also increased insulin biosynthesis and glucose-stimulated secretion in an ERK-dependent manner. Collectively, these results suggest that neuronal dCbl regulates life span, stress responses, and metabolism by suppressing dILP production and the EGFR-ERK pathway mediates the dCbl action. Cbl suppression of insulin biosynthesis is evolutionarily conserved, raising the possibility that Cbl may similarly exert its physiological actions through regulating insulin production in β cells.
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Li X, Xue B, Wang X, Sun L, Zhang T, Qu L, Zou X, Mu Y. Reduced expression of the LRP16 gene in mouse insulinoma (MIN6) cells exerts multiple effects on insulin content, proliferation and apoptosis. ACTA ACUST UNITED AC 2012; 32:190-198. [PMID: 22528219 DOI: 10.1007/s11596-012-0034-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2011] [Indexed: 01/12/2023]
Abstract
This study assessed the effects of leukemia-related protein 16 (LRP16) on the regulation of pancreatic functions in mouse insulinoma (MIN6) cells. Cells with down-regulated expression of LRP16 were obtained by a shRNA interference strategy. Insulin content and glucose-stimulated insulin secretion (GSIS) were examined by radioimmunoassay. Western blotting was applied to detect protein expression. Glucose-stimulated sub-cellular localization of PDX-1 was immunocytochemically determined. Cell proliferation and apoptosis were detected by flow cytometry. Our results showed that LRP16 regulated insulin content in MIN6 cells by controlling expression of insulin and insulin transcription factors. LRP16 gene silence in MIN6 cells led to reduced cell proliferation and increased apoptosis. The observation of phosphorylation of serine-473 Akt and the localization of PDX-1 to the nucleus under glucose-stimulation exhibited that LRP16 was a component mediating Akt signaling in MIN6 cells. These results suggest that LRP16 plays a key role in maintaining pancreatic β-cell functions and may help us to understand the protective effects of estrogen on the functions of pancreatic β-cells.
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Affiliation(s)
- Xiaojin Li
- Department of Endocrinology, Chinese PLA General Hospital, Beijing, 100853, China
| | - Bing Xue
- Department of Endocrinology, Chinese PLA General Hospital, Beijing, 100853, China
| | - Xuan Wang
- Department of Endocrinology, Chinese PLA General Hospital, Beijing, 100853, China
| | - Lianqing Sun
- Department of Endocrinology, Chinese PLA General Hospital, Beijing, 100853, China
| | - Tingting Zhang
- Department of Endocrinology, Chinese PLA General Hospital, Beijing, 100853, China
| | - Ling Qu
- Department of Endocrinology, Chinese PLA General Hospital, Beijing, 100853, China
| | - Xiaoman Zou
- Department of Endocrinology, Chinese PLA General Hospital, Beijing, 100853, China
| | - Yiming Mu
- Department of Endocrinology, Chinese PLA General Hospital, Beijing, 100853, China.
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Taurine supplementation prevents morpho-physiological alterations in high-fat diet mice pancreatic β-cells. Amino Acids 2012; 43:1791-801. [DOI: 10.1007/s00726-012-1263-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Accepted: 02/29/2012] [Indexed: 01/11/2023]
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Taniguchi S, Kimura T, Umeki T, Kimura Y, Kimura H, Ishii I, Itoh N, Naito Y, Yamamoto H, Niki I. Protein phosphorylation involved in the gene expression of the hydrogen sulphide producing enzyme cystathionine γ-lyase in the pancreatic β-cell. Mol Cell Endocrinol 2012; 350:31-8. [PMID: 22133746 DOI: 10.1016/j.mce.2011.11.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2011] [Revised: 11/16/2011] [Accepted: 11/16/2011] [Indexed: 01/24/2023]
Abstract
Cystathionine γ-lyase (CSE) is one of the major enzymes for the production of hydrogen sulphide (H(2)S), a multifunctional gasotransmitter in the pancreatic β-cell. We examined the mechanisms by which glucose induces CSE expression in mouse pancreatic islets and the insulin-secreting cell line MIN6. CSE expression was increased by anti-diabetic sulphonylureas, and decreased by the ATP-sensitive K(+)-channel opener diazoxide and the voltage-dependent Ca(2+) channel blocker nitrendipine. Application of the synthetic inhibitors of protein kinases revealed the involvement of Ca(2+)/calmodulin-dependent protein kinase (CaMK) II and extracellular signal-regulated protein kinase (ERK) in glucose- and thapsigargin-induced CSE expression. The CaMK IIδ knockdown also suppressed CSE expression. Knockdown of the transcription factors Sp1 and Elk1, both of which can be phosphorylated by ERK, blunted CSE expression. By a reporter assay, we found Sp1 may directly and Elk1 may indirectly regulate CSE expression. These findings suggest Ca(2+)-dependent CSE expression may be mediated via protein phosphorylation of Sp1 and Elk1 in pancreatic β-cells.
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Affiliation(s)
- Shigeki Taniguchi
- Department of Pharmacology, Oita University, 1-1 Idaigaoka, Hasama, Oita 879-5593, Japan
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Calegari VC, Abrantes JL, Silveira LR, Paula FM, Costa JM, Rafacho A, Velloso LA, Carneiro EM, Bosqueiro JR, Boschero AC, Zoppi CC. Endurance training stimulates growth and survival pathways and the redox balance in rat pancreatic islets. J Appl Physiol (1985) 2012; 112:711-8. [DOI: 10.1152/japplphysiol.00318.2011] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Endurance training has been shown to increase pancreatic β-cell function and mass. However, whether exercise modulates β-cell growth and survival pathways signaling is not completely understood. This study investigated the effects of exercise on growth and apoptotic markers levels in rat pancreatic islets. Male Wistar rats were randomly assigned to 8-wk endurance training or to a sedentary control group. After that, pancreatic islets were isolated; gene expression and the total content and phosphorylation of several proteins related to growth and apoptotic pathways as well as the main antioxidant enzymes were determined by real-time polymerase chain reaction and Western blot analysis, respectively. Reactive oxygen species (ROS) production was measured by fluorescence. Endurance training increased the time to reach fatigue by 50%. Endurance training resulted in increased protein phosphorylation content of AKT (75%), AKT substrate (AS160; 100%), mTOR (60%), p70s6k (90%), and ERK1/2 (50%), compared with islets from control group. Catalase protein content was 50% higher, whereas ROS production was 49 and 77% lower in islets from trained rats under basal and stimulating glucose conditions, respectively. Bcl-2 mRNA and protein levels increased by 46 and 100%, respectively. Bax and cleaved caspase-3 protein contents were reduced by 25 and 50% in islets from trained rats, respectively. In conclusion, these results demonstrate that endurance training favors the β-cell growth and survival by activating AKT and ERK1/2 pathways, enhancing antioxidant capacity, and reducing ROS production and apoptotic proteins content.
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Affiliation(s)
- Vivian C. Calegari
- Department of Anatomy, Cellular Biology and Physiology and Biophysics, Institute of Biology and
| | - Julia L. Abrantes
- Department of Anatomy, Cellular Biology and Physiology and Biophysics, Institute of Biology and
| | - Leonardo R. Silveira
- School of Physical Education and Sports, Faculty of Medicine, Department of Biochemistry and Immunology, University of Sao Paulo (USP), Ribeirão Preto, Sao Paulo
| | - Flavia M. Paula
- Department of Anatomy, Cellular Biology and Physiology and Biophysics, Institute of Biology and
| | - José Maria Costa
- Department of Anatomy, Cellular Biology and Physiology and Biophysics, Institute of Biology and
| | - Alex Rafacho
- Department of Anatomy, Cellular Biology and Physiology and Biophysics, Institute of Biology and
- Department of Physiological Sciences, Center of Biological Sciences, Federal University of Santa Catarina (UFSC), Florianopolis, Santa Catarina; and
| | - Lício A. Velloso
- Laboratory of Cell Signaling, State University of Campinas (UNICAMP), Campinas
| | - Everardo M. Carneiro
- Department of Anatomy, Cellular Biology and Physiology and Biophysics, Institute of Biology and
| | - Jose R. Bosqueiro
- Department of Physical Education, School of Science, Sao Paulo State University, UNESP, Bauru, Sao Paulo, Brazil
| | - Antonio C. Boschero
- Department of Anatomy, Cellular Biology and Physiology and Biophysics, Institute of Biology and
| | - Claudio C. Zoppi
- Department of Anatomy, Cellular Biology and Physiology and Biophysics, Institute of Biology and
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Volkmar M, Dedeurwaerder S, Cunha DA, Ndlovu MN, Defrance M, Deplus R, Calonne E, Volkmar U, Igoillo-Esteve M, Naamane N, Del Guerra S, Masini M, Bugliani M, Marchetti P, Cnop M, Eizirik DL, Fuks F. DNA methylation profiling identifies epigenetic dysregulation in pancreatic islets from type 2 diabetic patients. EMBO J 2012; 31:1405-26. [PMID: 22293752 PMCID: PMC3321176 DOI: 10.1038/emboj.2011.503] [Citation(s) in RCA: 289] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Accepted: 12/12/2011] [Indexed: 12/17/2022] Open
Abstract
In addition to genetic predisposition, environmental and lifestyle factors contribute to the pathogenesis of type 2 diabetes (T2D). Epigenetic changes may provide the link for translating environmental exposures into pathological mechanisms. In this study, we performed the first comprehensive DNA methylation profiling in pancreatic islets from T2D and non-diabetic donors. We uncovered 276 CpG loci affiliated to promoters of 254 genes displaying significant differential DNA methylation in diabetic islets. These methylation changes were not present in blood cells from T2D individuals nor were they experimentally induced in non-diabetic islets by exposure to high glucose. For a subgroup of the differentially methylated genes, concordant transcriptional changes were present. Functional annotation of the aberrantly methylated genes and RNAi experiments highlighted pathways implicated in β-cell survival and function; some are implicated in cellular dysfunction while others facilitate adaptation to stressors. Together, our findings offer new insights into the intricate mechanisms of T2D pathogenesis, underscore the important involvement of epigenetic dysregulation in diabetic islets and may advance our understanding of T2D aetiology.
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Affiliation(s)
- Michael Volkmar
- Laboratory of Cancer Epigenetics, Faculty of Medicine, Université Libre de Bruxelles, Brussels, Belgium
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Li JL, Zhao L, Cui B, Deng LF, Ning G, Liu JM. Multiple signaling pathways involved in stimulation of osteoblast differentiation by N-methyl-D-aspartate receptors activation in vitro. Acta Pharmacol Sin 2011; 32:895-903. [PMID: 21685927 DOI: 10.1038/aps.2011.38] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
AIM Glutamate receptors are expressed in osteoblastic cells. The present study was undertaken to investigate the mechanisms underlying the stimulation of osteoblast differentiation by N-methyl-D-aspartate (NMDA) receptor activation in vitro. METHODS Primary culture of osteoblasts was prepared from SD rats. Microarray was used to detect the changes of gene expression. The effect of NMDA receptor agonist or antagonist on individual gene was examined using RT-PCR. The activity of alkaloid phosphotase (ALP) was assessed using a commercial ALP staining kit. RESULTS Microarray analyses revealed that 10 genes were up-regulated by NMDA (0.5 mmol/L) and down-regulated by MK801 (100 μmol/L), while 13 genes down-regulated by NMDA (0.5 mmol/L) and up-regulated by MK801 (100 μmol/L). Pretreatment of osteoblasts with the specific PKC inhibitor Calphostin C (0.05 μmol/L), the PKA inhibitor H-89 (20 nmol/L), or the PI3K inhibitor wortmannin (100 nmol/L) blocked the ALP activity increase caused by NMDA (0.5 mmol/L). Furthermore, NMDA (0.5 mmol/L) rapidly increased PI3K phosphorylation, which could be blocked by pretreatment of wortmannin (100 nmol/L). CONCLUSION The results suggest that activation of NMDA receptors stimulates osteoblasts differentiation through PKA, PKC, and PI3K signaling pathways, which is a new role for glutamate in regulating bone remodeling.
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Bouzakri K, Plomgaard P, Berney T, Donath MY, Pedersen BK, Halban PA. Bimodal effect on pancreatic β-cells of secretory products from normal or insulin-resistant human skeletal muscle. Diabetes 2011; 60:1111-21. [PMID: 21378173 PMCID: PMC3064085 DOI: 10.2337/db10-1178] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
OBJECTIVE Type 2 diabetes is characterized by insulin resistance with a relative deficiency in insulin secretion. This study explored the potential communication between insulin-resistant human skeletal muscle and primary (human and rat) β-cells. RESEARCH DESIGN AND METHODS Human skeletal muscle cells were cultured for up to 24 h with tumor necrosis factor (TNF)-α to induce insulin resistance, and mRNA expression for cytokines was analyzed and compared with controls (without TNF-α). Conditioned media were collected and candidate cytokines were measured by antibody array. Human and rat primary β-cells were used to explore the impact of exposure to conditioned media for 24 h on apoptosis, proliferation, short-term insulin secretion, and key signaling protein phosphorylation and expression. RESULTS Human myotubes express and release a different panel of myokines depending on their insulin sensitivity, with each panel exerting differential effects on β-cells. Conditioned medium from control myotubes increased proliferation and glucose-stimulated insulin secretion (GSIS) from primary β-cells, whereas conditioned medium from TNF-α-treated insulin-resistant myotubes (TMs) exerted detrimental effects that were either independent (increased apoptosis and decreased proliferation) or dependent on the presence of TNF-α in TM (blunted GSIS). Knockdown of β-cell mitogen-activated protein 4 kinase 4 prevented these effects. Glucagon-like peptide 1 protected β-cells against decreased proliferation and apoptosis evoked by TMs, while interleukin-1 receptor antagonist only prevented the latter. CONCLUSIONS Taken together, these data suggest a possible new route of communication between skeletal muscle and β-cells that is modulated by insulin resistance and could contribute to normal β-cell functional mass in healthy subjects, as well as the decrease seen in type 2 diabetes.
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Affiliation(s)
- Karim Bouzakri
- Department of Genetic Medicine and Development, University Medical Center, University of Geneva, Geneva, Switzerland.
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Dalle S, Ravier MA, Bertrand G. Emerging roles for β-arrestin-1 in the control of the pancreatic β-cell function and mass: New therapeutic strategies and consequences for drug screening. Cell Signal 2011; 23:522-8. [DOI: 10.1016/j.cellsig.2010.09.014] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2010] [Accepted: 09/06/2010] [Indexed: 01/09/2023]
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Genomic collaboration of estrogen receptor alpha and extracellular signal-regulated kinase 2 in regulating gene and proliferation programs. Mol Cell Biol 2010; 31:226-36. [PMID: 20956553 DOI: 10.1128/mcb.00821-10] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The nuclear hormone receptor, estrogen receptor α (ERα), and mitogen-activated protein kinases (MAPKs) play key roles in hormone-dependent cancers, and yet their interplay and the integration of their signaling inputs remain poorly understood. In these studies, we document that estrogen-occupied ERα activates and interacts with extracellular signal-regulated kinase 2 (ERK2), a downstream effector in the MAPK pathway, resulting in ERK2 and ERα colocalization at chromatin binding sites across the genome of breast cancer cells. This genomic colocalization, predominantly at conserved distal enhancer sites, requires the activation of both ERα and ERK2 and enables ERK2 modulation of estrogen-dependent gene expression and proliferation programs. The ERK2 substrate CREB1 was also activated and recruited to ERK2-bound chromatin following estrogen treatment and found to cooperate with ERα/ERK2 in regulating gene transcription and cell cycle progression. Our study reveals a novel paradigm with convergence of ERK2 and ERα at the chromatin level that positions this kinase to support nuclear receptor activities in crucial and direct ways, a mode of collaboration likely to underlie MAPK regulation of gene expression by other nuclear receptors as well.
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