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Serra-Navarro B, Fernandez-Ruiz R, García-Alamán A, Pradas-Juni M, Fernandez-Rebollo E, Esteban Y, Mir-Coll J, Mathieu J, Dalle S, Hahn M, Ahlgren U, Weinstein LS, Vidal J, Gomis R, Gasa R. Gsα-dependent signaling is required for postnatal establishment of a functional β-cell mass. Mol Metab 2021; 53:101264. [PMID: 34091063 PMCID: PMC8239471 DOI: 10.1016/j.molmet.2021.101264] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 05/17/2021] [Accepted: 05/30/2021] [Indexed: 12/01/2022] Open
Abstract
OBJECTIVE Early postnatal life is a critical period for the establishment of the functional β-cell mass that will sustain whole-body glucose homeostasis during the lifetime. β cells are formed from progenitors during embryonic development but undergo significant expansion in quantity and attain functional maturity after birth. The signals and pathways involved in these processes are not fully elucidated. Cyclic adenosine monophosphate (cAMP) is an intracellular signaling molecule that is known to regulate insulin secretion, gene expression, proliferation, and survival of adult β cells. The heterotrimeric G protein Gs stimulates the cAMP-dependent pathway by activating adenylyl cyclase. In this study, we sought to explore the role of Gs-dependent signaling in postnatal β-cell development. METHODS To study Gs-dependent signaling, we generated conditional knockout mice in which the α subunit of the Gs protein (Gsα) was ablated from β-cells using the Cre deleter line Ins1Cre. Mice were characterized in terms of glucose homeostasis, including in vivo glucose tolerance, glucose-induced insulin secretion, and insulin sensitivity. β-cell mass was studied using histomorphometric analysis and optical projection tomography. β-cell proliferation was studied by ki67 and phospho-histone H3 immunostatining, and apoptosis was assessed by TUNEL assay. Gene expression was determined in isolated islets and sorted β cells by qPCR. Intracellular cAMP was studied in isolated islets using HTRF-based technology. The activation status of the cAMP and insulin-signaling pathways was determined by immunoblot analysis of the relevant components of these pathways in isolated islets. In vitro proliferation of dissociated islet cells was assessed by BrdU incorporation. RESULTS Elimination of Gsα in β cells led to reduced β-cell mass, deficient insulin secretion, and severe glucose intolerance. These defects were evident by weaning and were associated with decreased proliferation and inadequate expression of key β-cell identity and maturation genes in postnatal β-cells. Additionally, loss of Gsα caused a broad multilevel disruption of the insulin transduction pathway that resulted in the specific abrogation of the islet proliferative response to insulin. CONCLUSION We conclude that Gsα is required for β-cell growth and maturation in the early postnatal stage and propose that this is partly mediated via its crosstalk with insulin signaling. Our findings disclose a tight connection between these two pathways in postnatal β cells, which may have implications for using cAMP-raising agents to promote β-cell regeneration and maturation in diabetes.
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Affiliation(s)
- Berta Serra-Navarro
- Diabetes and Obesity Research Laboratory, August Pi i Sunyer Biomedical Research Institute (IDIBAPS), Rosselló 149-153, 08036, Barcelona, Spain; University of Barcelona, Barcelona, Spain
| | - Rebeca Fernandez-Ruiz
- Diabetes and Obesity Research Laboratory, August Pi i Sunyer Biomedical Research Institute (IDIBAPS), Rosselló 149-153, 08036, Barcelona, Spain; University of Barcelona, Barcelona, Spain; Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Spain
| | - Ainhoa García-Alamán
- Diabetes and Obesity Research Laboratory, August Pi i Sunyer Biomedical Research Institute (IDIBAPS), Rosselló 149-153, 08036, Barcelona, Spain; Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Spain
| | - Marta Pradas-Juni
- Diabetes and Obesity Research Laboratory, August Pi i Sunyer Biomedical Research Institute (IDIBAPS), Rosselló 149-153, 08036, Barcelona, Spain; University of Barcelona, Barcelona, Spain
| | - Eduardo Fernandez-Rebollo
- Diabetes and Obesity Research Laboratory, August Pi i Sunyer Biomedical Research Institute (IDIBAPS), Rosselló 149-153, 08036, Barcelona, Spain; Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Spain
| | - Yaiza Esteban
- Diabetes and Obesity Research Laboratory, August Pi i Sunyer Biomedical Research Institute (IDIBAPS), Rosselló 149-153, 08036, Barcelona, Spain; Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Spain
| | - Joan Mir-Coll
- Diabetes and Obesity Research Laboratory, August Pi i Sunyer Biomedical Research Institute (IDIBAPS), Rosselló 149-153, 08036, Barcelona, Spain; University of Barcelona, Barcelona, Spain
| | - Julia Mathieu
- CHU Montpellier, Laboratory of Cell Therapy for Diabetes (LTCD), Hospital St-Eloi, Montpellier, France
| | - Stephane Dalle
- CHU Montpellier, Laboratory of Cell Therapy for Diabetes (LTCD), Hospital St-Eloi, Montpellier, France
| | - Max Hahn
- Umeå Centre for Molecular Medicine (UCMM), Umeå, Sweden
| | - Ulf Ahlgren
- Umeå Centre for Molecular Medicine (UCMM), Umeå, Sweden
| | - Lee S Weinstein
- Metabolic Diseases Branch, National Institute of Diabetes, Digestive, and Kidney Diseases, NIH, Bethesda, MD, USA
| | - Josep Vidal
- Diabetes and Obesity Research Laboratory, August Pi i Sunyer Biomedical Research Institute (IDIBAPS), Rosselló 149-153, 08036, Barcelona, Spain; University of Barcelona, Barcelona, Spain; Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Spain; Department of Endocrinology and Nutrition, Hospital Clinic of Barcelona, Barcelona, Spain
| | - Ramon Gomis
- Diabetes and Obesity Research Laboratory, August Pi i Sunyer Biomedical Research Institute (IDIBAPS), Rosselló 149-153, 08036, Barcelona, Spain; University of Barcelona, Barcelona, Spain; Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Spain; Universitat Oberta de Catalunya (UOC), Barcelona, Spain
| | - Rosa Gasa
- Diabetes and Obesity Research Laboratory, August Pi i Sunyer Biomedical Research Institute (IDIBAPS), Rosselló 149-153, 08036, Barcelona, Spain; Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Spain.
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2
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Takatani T, Shirakawa J, Shibue K, Gupta MK, Kim H, Lu S, Hu J, White MF, Kennedy RT, Kulkarni RN. Insulin receptor substrate 1, but not IRS2, plays a dominant role in regulating pancreatic alpha cell function in mice. J Biol Chem 2021; 296:100646. [PMID: 33839150 PMCID: PMC8131928 DOI: 10.1016/j.jbc.2021.100646] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 03/24/2021] [Accepted: 04/07/2021] [Indexed: 11/29/2022] Open
Abstract
Dysregulated glucagon secretion deteriorates glycemic control in type 1 and type 2 diabetes. Although insulin is known to regulate glucagon secretion via its cognate receptor (insulin receptor, INSR) in pancreatic alpha cells, the role of downstream proteins and signaling pathways underlying insulin's activities are not fully defined. Using in vivo (knockout) and in vitro (knockdown) studies targeting insulin receptor substrate (IRS) proteins, we compared the relative roles of IRS1 and IRS2 in regulating alpha cell function. Alpha cell-specific IRS1-knockout mice exhibited glucose intolerance and inappropriate glucagon suppression during glucose tolerance tests. In contrast, alpha cell-specific IRS2-knockout animals manifested normal glucose tolerance and suppression of glucagon secretion after glucose administration. Alpha cell lines with stable IRS1 knockdown could not repress glucagon mRNA expression and exhibited a reduction in phosphorylation of AKT Ser/Thr kinase (AKT, at Ser-473 and Thr-308). AlphaIRS1KD cells also displayed suppressed global protein translation, including reduced glucagon expression, impaired cytoplasmic Ca2+ response, and mitochondrial dysfunction. This was supported by the identification of novel IRS1-specific downstream target genes, Trpc3 and Cartpt, that are associated with glucagon regulation in alpha cells. These results provide evidence that IRS1, rather than IRS2, is a dominant regulator of pancreatic alpha cell function.
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Affiliation(s)
- Tomozumi Takatani
- Islet Cell and Regenerative Biology, Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA; Department of Pediatrics, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Jun Shirakawa
- Laboratory of Diabetes and Metabolic Disorders, Institute for Molecular and Cellular Regulation (IMCR), Gunma University, Gunma, Japan
| | - Kimitaka Shibue
- Islet Cell and Regenerative Biology, Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Manoj K Gupta
- Islet Cell and Regenerative Biology, Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA; Cell Therapy Translational Engine (CTTE), Takeda Pharmaceuticals, Cambridge, Massachusetts, USA
| | - Hyunki Kim
- Islet Cell and Regenerative Biology, Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Shusheng Lu
- Departments of Chemistry and Pharmacology, University of Michigan, Ann Arbor, Michigan, USA
| | - Jiang Hu
- Islet Cell and Regenerative Biology, Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Morris F White
- Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Robert T Kennedy
- Departments of Chemistry and Pharmacology, University of Michigan, Ann Arbor, Michigan, USA
| | - Rohit N Kulkarni
- Islet Cell and Regenerative Biology, Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA; Harvard Stem Cell Institute, Harvard Medical School, Boston, Massachusetts, USA.
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3
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Guay C, Jacovetti C, Bayazit MB, Brozzi F, Rodriguez-Trejo A, Wu K, Regazzi R. Roles of Noncoding RNAs in Islet Biology. Compr Physiol 2020; 10:893-932. [PMID: 32941685 DOI: 10.1002/cphy.c190032] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The discovery that most mammalian genome sequences are transcribed to ribonucleic acids (RNA) has revolutionized our understanding of the mechanisms governing key cellular processes and of the causes of human diseases, including diabetes mellitus. Pancreatic islet cells were found to contain thousands of noncoding RNAs (ncRNAs), including micro-RNAs (miRNAs), PIWI-associated RNAs, small nucleolar RNAs, tRNA-derived fragments, long non-coding RNAs, and circular RNAs. While the involvement of miRNAs in islet function and in the etiology of diabetes is now well documented, there is emerging evidence indicating that other classes of ncRNAs are also participating in different aspects of islet physiology. The aim of this article will be to provide a comprehensive and updated view of the studies carried out in human samples and rodent models over the past 15 years on the role of ncRNAs in the control of α- and β-cell development and function and to highlight the recent discoveries in the field. We not only describe the role of ncRNAs in the control of insulin and glucagon secretion but also address the contribution of these regulatory molecules in the proliferation and survival of islet cells under physiological and pathological conditions. It is now well established that most cells release part of their ncRNAs inside small extracellular vesicles, allowing the delivery of genetic material to neighboring or distantly located target cells. The role of these secreted RNAs in cell-to-cell communication between β-cells and other metabolic tissues as well as their potential use as diabetes biomarkers will be discussed. © 2020 American Physiological Society. Compr Physiol 10:893-932, 2020.
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Affiliation(s)
- Claudiane Guay
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland.,Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Cécile Jacovetti
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland.,Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Mustafa Bilal Bayazit
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland.,Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Flora Brozzi
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland.,Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Adriana Rodriguez-Trejo
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland.,Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Kejing Wu
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland.,Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Romano Regazzi
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland.,Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
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4
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Mizgier ML, Fernández-Verdejo R, Cherfan J, Pinget M, Bouzakri K, Galgani JE. Insights on the Role of Putative Muscle-Derived Factors on Pancreatic Beta Cell Function. Front Physiol 2019; 10:1024. [PMID: 31440170 PMCID: PMC6694406 DOI: 10.3389/fphys.2019.01024] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Accepted: 07/24/2019] [Indexed: 01/02/2023] Open
Abstract
Skeletal muscle is a main target of insulin action that plays a pivotal role in postprandial glucose disposal. Importantly, skeletal muscle insulin sensitivity relates inversely with pancreatic insulin secretion, which prompted the hypothesis of the existence of a skeletal muscle-pancreas crosstalk mediated through an endocrine factor. The observation that changes in skeletal muscle glucose metabolism are accompanied by altered insulin secretion supports this hypothesis. Meanwhile, a muscle-derived circulating factor affecting in vivo insulin secretion remains elusive. This factor may correspond to peptides/proteins (so called myokines), exosomes and their cargo, and metabolites. We hereby review the most remarkable evidence encouraging the possibility of such inter-organ communication, with special focus on muscle-derived factors that may potentially mediate such skeletal muscle-pancreas crosstalk.
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Affiliation(s)
- Maria L Mizgier
- UMR DIATHEC, EA 7294, Centre Européen d'Etude du Diabète, Université de Strasbourg, Strasbourg, France
| | - Rodrigo Fernández-Verdejo
- Departamento de Ciencias de la Salud, Nutrición y Dietética, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Julien Cherfan
- UMR DIATHEC, EA 7294, Centre Européen d'Etude du Diabète, Université de Strasbourg, Strasbourg, France
| | - Michel Pinget
- UMR DIATHEC, EA 7294, Centre Européen d'Etude du Diabète, Université de Strasbourg, Strasbourg, France
| | - Karim Bouzakri
- UMR DIATHEC, EA 7294, Centre Européen d'Etude du Diabète, Université de Strasbourg, Strasbourg, France
| | - Jose E Galgani
- Departamento de Ciencias de la Salud, Nutrición y Dietética, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.,Departamento de Nutrición, Diabetes y Metabolismo, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
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5
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Oakie A, Wang R. β-Cell Receptor Tyrosine Kinases in Controlling Insulin Secretion and Exocytotic Machinery: c-Kit and Insulin Receptor. Endocrinology 2018; 159:3813-3821. [PMID: 30239687 PMCID: PMC6202852 DOI: 10.1210/en.2018-00716] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 09/13/2018] [Indexed: 12/25/2022]
Abstract
Insulin secretion from pancreatic β-cells is initiated through channel-mediated depolarization, cytoskeletal remodeling, and vesicle tethering at the cell membrane, all of which can be regulated through cell surface receptors. Receptor tyrosine kinases (RTKs) promote β-cell development and postnatal signaling to improve β-cell mass and function, yet their activation has also been shown to initiate exocytotic events in β-cells. This review examines the role of RTK signaling in insulin secretion, with a focus on RTKs c-Kit and insulin receptor (IR). Pathways that control insulin release and the potential interplay between c-Kit and IR signaling are discussed, along with clinical implications of RTK therapy on insulin secretion.
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Affiliation(s)
- Amanda Oakie
- Children’s Health Research Institute, Victoria Research Laboratories, London, Ontario, Canada
- Department of Pathology and Laboratory Medicine, University of Western Ontario, London, Ontario, Canada
| | - Rennian Wang
- Children’s Health Research Institute, Victoria Research Laboratories, London, Ontario, Canada
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
- Department of Medicine, University of Western Ontario, London, Ontario, Canada
- Correspondence: Rennian Wang, MD, PhD, Victoria Research Laboratories, Room A5-140, 800 Commissioners Road East, London, Ontario N6C 2V5, Canada. E-mail:
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6
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Jiang WJ, Peng YC, Yang KM. Cellular signaling pathways regulating β-cell proliferation as a promising therapeutic target in the treatment of diabetes. Exp Ther Med 2018; 16:3275-3285. [PMID: 30233674 PMCID: PMC6143874 DOI: 10.3892/etm.2018.6603] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 07/27/2018] [Indexed: 12/30/2022] Open
Abstract
It is established that a decrease in β-cell number and deficiency in the function of existing β-cells contribute to type 1 and type 2 diabetes mellitus. Therefore, a major focus of current research is to identify novel methods of improving the number and function of β-cells, so as to prevent and/or postpone the development of diabetes mellitus and potentially reverse diabetes mellitus. Based on prior knowledge of the above-mentioned causes, promising therapeutic approaches may include direct transplantation of islets, implantation and subsequent induced differentiation of progenitors/stem cells to β-cells, replication of pre-existing β-cells, or activation of endogenous β-cell progenitors. More recently, with regards to cell replacement and regenerative treatment for diabetes patients, the identification of cellular signaling pathways with related genes or corresponding proteins involved in diabetes has become a topic of interest. However, the majority of pathways and molecules associated with β-cells remain unresolved, and the specialized functions of known pathways remain unclear, particularly in humans. The current article has evaluated the progress of research on pivotal cellular signaling pathways involved with β-cell proliferation and survival, and their validity for therapeutic adult β-cell regeneration in diabetes. More efforts are required to elucidate the cellular events involved in human β-cell proliferation in terms of the underlying mechanisms and functions.
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Affiliation(s)
- Wen-Juan Jiang
- Institute of Anatomy, Basic Medical College of Dali University, Dali, Yunnan 671000, P.R. China
| | - Yun-Chuan Peng
- Institute of Anatomy, Basic Medical College of Dali University, Dali, Yunnan 671000, P.R. China
| | - Kai-Ming Yang
- Institute of Anatomy, Basic Medical College of Dali University, Dali, Yunnan 671000, P.R. China
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7
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Song Z, Wang H, Zhu L, Han M, Gao Y, Du Y, Wen Y. Curcumin improves high glucose-induced INS-1 cell insulin resistance via activation of insulin signaling. Food Funct 2016; 6:461-9. [PMID: 25474544 DOI: 10.1039/c4fo00608a] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Curcumin is a yellow pigment isolated from Corcuma longan. This research investigates the improvement of curcumin on INS-1 cells with insulin resistance induced by high glucose. INS-1 cells were treated with high glucose (30 mmol L(-1)) for 48 h. Subsequently, the medium was replaced with curcumin for 24 h. Curcumin effectively increased insulin gene expression and glucose stimulated insulin secretion (GSIS) in a dose-dependent manner. Furthermore, the molecular mechanism of curcumin-induced insulin expression and secretion in high glucose-induced INS-1 cells was investigated in this study. Curcumin increased the expression of glucose transporter 2 (GLUT2) and phosphorylation of insulin receptor (IR), insulin receptor substrate-1 (IRS1), phosphatidylinositol-3-kinase (PI3K) and AKT in the INS-1 cells. Moreover, curcumin stimulation increased the expression of PDX-1 and GCK. This investigation suggests that curcumin prevented high glucose-reduced insulin expression and secretion through activation of the PI3K/Akt/GLUT2 pathway in INS-1 cells.
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Affiliation(s)
- Zhenfeng Song
- Department of Nutrition and Food Hygiene, School of Public Health, Harbin Medical University, 157 Baojian Road, Nangang District, 150086, Harbin, People's Republic of China.
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8
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Huang X, Tang J, Xu J, Jia G, Liu G, Chen X, Cai J, Shang H, Zhao H. Supranutritional dietary selenium induced hyperinsulinemia and dyslipidemia via affected expression of selenoprotein genes and insulin signal-related genes in broiler. RSC Adv 2016. [DOI: 10.1039/c6ra14932d] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The purpose of this study was to investigate the effects of supranutritional selenium (Se) on the mRNA expression of selenoprotein genes and insulin signal-related genes in the liver, muscle and pancreas of the broiler.
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Affiliation(s)
- Xiaofeng Huang
- Animal Nutrition Institute
- Sichuan Agricultural University
- Chengdu
- China
| | - Jiayong Tang
- Animal Nutrition Institute
- Sichuan Agricultural University
- Chengdu
- China
| | - Jingyang Xu
- Animal Nutrition Institute
- Sichuan Agricultural University
- Chengdu
- China
| | - Gang Jia
- Animal Nutrition Institute
- Sichuan Agricultural University
- Chengdu
- China
| | - Guangmang Liu
- Animal Nutrition Institute
- Sichuan Agricultural University
- Chengdu
- China
| | - Xiaoling Chen
- Animal Nutrition Institute
- Sichuan Agricultural University
- Chengdu
- China
| | - Jingyi Cai
- Animal Nutrition Institute
- Sichuan Agricultural University
- Chengdu
- China
| | - Haiying Shang
- Animal Nutrition Institute
- Sichuan Agricultural University
- Chengdu
- China
| | - Hua Zhao
- Animal Nutrition Institute
- Sichuan Agricultural University
- Chengdu
- China
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9
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Wen YQ, Tan YC, Lv DT, Zhang PB, Ren ZQ. Influence of gastric bypass on pancreatic insulin resistance in type 2 diabetic rats. Shijie Huaren Xiaohua Zazhi 2014; 22:1431-1435. [DOI: 10.11569/wcjd.v22.i10.1431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To observe the influence of gastric bypass on pancreatic insulin resistance in type 2 diabetic rats.
METHODS: Twenty-four type 2 diabetic SD rats were randomly and equally divided into three groups: a gastric bypass group (T group), a food control group (F group), and a type 2 diabetes control group (C group). Plasma levels of glucose, insulin, quantitative insulin sensitivity check index and protein expression of pancreatic insulin receptor substrates-1 and -2 (IRS-1,2) were measured preoperatively and at weeks 1, 2, 4 and 8 postoperatively.
RESULTS: Fasting blood glucose in the T group decreased from week 1 after gastric bypass and reached 5.79 mmol/L ± 1.83 mmol/L at week 8 (P < 0.05). Fasting plasma insulin (FINS) in the T group slightly increased at week 1 after surgery, then decreased and reached 7.69 mU/L ± 1.73 mU/L at week 8 (P < 0.05). In contrast, fasting blood glucose and FINS showed no significant changes after surgery in the F and C groups (P > 0.05 for all). QUICKI had a dramatic increase in the T group, from 0.44 ± 0.05 preoperatively to 0.61 ± 0.05 (P < 0.05) 8 weeks post operation, while the F and C groups showed no significant changes after operation (P > 0.05 for both). Compared with the C group, a significant increase in the expression of IRS-1, 2 proteins was observed in the T group 8 weeks postoperatively (P < 0.05), although no significant difference was observed in the F and C groups (P > 0.05).
CONCLUSION: GBP can improve the expression of hepatic IRS-1, 2 and thus increase pancreatic insulin sensitivity in rats with type 2 diabetes mellitus.
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Abstract
OBJECTIVES We investigated the influence of leucine supplementation on insulin secretion and on some proteins related to insulin secretion in malnourished mice. METHODS Swiss mice (aged 21 days) received isocaloric normo-17% (NP) or 6% low-protein (LP) diet for 120 days. Half of the NP and LP mice received 1.5% leucine in the drinking water during the last 30 days (NPL and LPL, respectively). RESULTS The LP mice were hypoinsulinemic compared with the NP group, whereas LPL mice exhibited increased insulinemia in the fed state versus LP mice. The LP mouse islets were less responsive to 22.2 mM glucose, 100 microM carbachol (Cch), and 10 mM leucine than the NP group. However, LPL islets were more responsive to all these conditions compared with the LP group. The muscarinic type 3 receptor, (M3R) Cabeta2, and PKC-alpha protein contents were reduced in LP compared with NP islets but significantly higher in LPL than LP islets. The p-AKT/AKT ratio was higher in LPL compared with LP islets. CONCLUSIONS Leucine supplementation increases insulin secretion in response to glucose and leucine and to agents that potentiate secretion, such as Cch, in malnourished mice. The enhanced levels of M3R, Cabeta2, and PKC-alpha proteins, as well as of the p-AKT/AKT ratio, may play a role in this process.
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Ropelle ER, Fernandes MFA, Flores MBS, Ueno M, Rocco S, Marin R, Cintra DE, Velloso LA, Franchini KG, Saad MJA, Carvalheira JBC. Central exercise action increases the AMPK and mTOR response to leptin. PLoS One 2008; 3:e3856. [PMID: 19052642 PMCID: PMC2585815 DOI: 10.1371/journal.pone.0003856] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2008] [Accepted: 11/06/2008] [Indexed: 11/19/2022] Open
Abstract
AMP-activated protein kinase (AMPK) and mammalian Target of Rapamycin (mTOR) are key regulators of cellular energy balance and of the effects of leptin on food intake. Acute exercise is associated with increased sensitivity to the effects of leptin on food intake in an IL-6-dependent manner. To determine whether exercise ameliorates the AMPK and mTOR response to leptin in the hypothalamus in an IL-6-dependent manner, rats performed two 3-h exercise bouts, separated by one 45-min rest period. Intracerebroventricular IL-6 infusion reduced food intake and pretreatment with AMPK activators and mTOR inhibitor prevented IL-6-induced anorexia. Activators of AMPK and fasting increased food intake in control rats to a greater extent than that observed in exercised ones, whereas inhibitor of AMPK had the opposite effect. Furthermore, the reduction of AMPK and ACC phosphorylation and increase in phosphorylation of proteins involved in mTOR signal transduction, observed in the hypothalamus after leptin infusion, were more pronounced in both lean and diet-induced obesity rats after acute exercise. Treatment with leptin reduced food intake in exercised rats that were pretreated with vehicle, although no increase in responsiveness to leptin-induced anorexia after pretreatment with anti-IL6 antibody, AICAR or Rapamycin was detected. Thus, the effects of leptin on the AMPK/mTOR pathway, potentiated by acute exercise, may contribute to appetite suppressive actions in the hypothalamus.
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Affiliation(s)
- Eduardo R. Ropelle
- Department of Internal Medicine, FCM, State University of Campinas (UNICAMP), Campinas, São Paulo, Brazil
| | | | - Marcelo B. S. Flores
- Department of Internal Medicine, FCM, State University of Campinas (UNICAMP), Campinas, São Paulo, Brazil
| | - Mirian Ueno
- Department of Internal Medicine, FCM, State University of Campinas (UNICAMP), Campinas, São Paulo, Brazil
| | - Silvana Rocco
- Department of Internal Medicine, FCM, State University of Campinas (UNICAMP), Campinas, São Paulo, Brazil
| | - Rodrigo Marin
- Department of Internal Medicine, FCM, State University of Campinas (UNICAMP), Campinas, São Paulo, Brazil
| | - Dennys E. Cintra
- Department of Internal Medicine, FCM, State University of Campinas (UNICAMP), Campinas, São Paulo, Brazil
| | - Lício A. Velloso
- Department of Internal Medicine, FCM, State University of Campinas (UNICAMP), Campinas, São Paulo, Brazil
| | - Kleber G. Franchini
- Department of Internal Medicine, FCM, State University of Campinas (UNICAMP), Campinas, São Paulo, Brazil
| | - Mario J. A. Saad
- Department of Internal Medicine, FCM, State University of Campinas (UNICAMP), Campinas, São Paulo, Brazil
| | - José B. C. Carvalheira
- Department of Internal Medicine, FCM, State University of Campinas (UNICAMP), Campinas, São Paulo, Brazil
- * E-mail:
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Abstract
The appropriate function of insulin-producing pancreatic beta-cells is crucial for the regulation of glucose homeostasis, and its impairment leads to diabetes mellitus, the most common metabolic disorder in man. In addition to glucose, the major nutrient factor, inputs from the nervous system, humoral components, and cell-cell communication within the islet of Langerhans act together to guarantee the release of appropriate amounts of insulin in response to changes in blood glucose levels. Data obtained within the past decade in several laboratories have revitalized controversy over the autocrine feedback action of secreted insulin on beta-cell function. Although insulin historically has been suggested to exert a negative effect on beta-cells, recent data provide evidence for a positive role of insulin in transcription, translation, ion flux, insulin secretion, proliferation, and beta-cell survival. Current insights on the role of insulin on pancreatic beta-cell function are discussed.
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Affiliation(s)
- Ingo B Leibiger
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden.
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13
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Involvement of phosphatidylinositol-3 kinase/AKT/PKCzeta/lambda pathway in the effect of palmitate on glucose-induced insulin secretion. Pancreas 2008; 37:309-15. [PMID: 18815554 DOI: 10.1097/mpa.0b013e318168dac3] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
OBJECTIVES In the present study, a novel pathway by which palmitate potentiates glucose-induced insulin secretion by pancreatic beta cells was investigated. METHODS Groups of freshly isolated islets were incubated in 10 mM glucose with palmitate, LY294002, wortmannin, and fumonisin B1 for measurement of insulin secretion by radioimmunoassay (RIA). Also, phosphorylation and content of AKT and PKC proteins were evaluated by immunoblotting. RESULTS Glucose plus palmitate and glucose plus LY294002 or wortmannin (PI3K inhibitors) increased glucose-induced insulin secretion by isolated pancreatic islets. Glucose at 10 mM induced AKT and PKCzeta/lambda phosphorylation. Palmitate (0.1 mM) abolished glucose stimulation of AKT and PKCzeta/lambda phosphorylation possibly through PI3K inhibition because both LY294002 (50 microM) and wortmannin (100 nM) caused the same effect. The inhibitory effect of palmitate on glucose-induced AKT and PKCzeta/lambda phosphorylation and the stimulatory effect of palmitate on glucose-induced insulin secretion were not observed in the presence of fumonisin B1, an inhibitor of ceramide synthesis. CONCLUSIONS These findings support the proposition that palmitate increases insulin release in the presence of 10 mM glucose by inhibiting PI3K activity through a mechanism that involves ceramide synthesis.
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Francini F, Gagliardino JJ, Borelli MI. Decreased islet sensitivity to insulin in hamsters with dietary-induced insulin resistance. Life Sci 2008; 82:817-22. [DOI: 10.1016/j.lfs.2008.01.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2007] [Revised: 12/21/2007] [Accepted: 01/21/2008] [Indexed: 10/22/2022]
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15
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Ropelle ER, Pauli JR, Fernandes MFA, Rocco SA, Marin RM, Morari J, Souza KK, Dias MM, Gomes-Marcondes MC, Gontijo JAR, Franchini KG, Velloso LA, Saad MJA, Carvalheira JBC. A central role for neuronal AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) in high-protein diet-induced weight loss. Diabetes 2008; 57:594-605. [PMID: 18057094 DOI: 10.2337/db07-0573] [Citation(s) in RCA: 151] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE A high-protein diet (HPD) is known to promote the reduction of body fat, but the mechanisms underlying this change are unclear. AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) function as majors regulators of cellular metabolism that respond to changes in energy status, and recent data demonstrated that they also play a critical role in systemic energy balance. Here, we sought to determine whether the response of the AMPK and mTOR pathways could contribute to the molecular effects of an HPD. RESEARCH DESIGN AND METHODS Western blotting, confocal microscopy, chromatography, light microscopy, and RT-PCR assays were combined to explore the anorexigenic effects of an HPD. RESULTS An HPD reduced food intake and induced weight loss in both normal rats and ob/ob mice. The intracerebroventricular administration of leucine reduced food intake, and the magnitude of weight loss and reduction of food intake in a leucine-supplemented diet are similar to that achieved by HPD in normal rats and in ob/ob mice, suggesting that leucine is a major component of the effects of an HPD. Leucine and HPD decrease AMPK and increase mTOR activity in the hypothalamus, leading to inhibition of neuropeptide Y and stimulation of pro-opiomelanocortin expression. Consistent with a cross-regulation between AMPK and mTOR to control food intake, our data show that the activation of these enzymes occurs in the same specific neuronal subtypes. CONCLUSIONS These findings provide support for the hypothesis that AMPK and mTOR interact in the hypothalamus to regulate feeding during HPD in a leucine-dependent manner.
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Affiliation(s)
- Eduardo R Ropelle
- Department of Internal Medicine, State University of Campinas (UNICAMP), 13083-970, Campinas, São Paulo, Brazil
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16
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Impaired insulin secretion and decreased expression of the nutritionally responsive ribosomal kinase protein S6K-1 in pancreatic islets from malnourished rats. Life Sci 2008; 82:542-8. [DOI: 10.1016/j.lfs.2007.12.012] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2007] [Revised: 09/25/2007] [Accepted: 12/15/2007] [Indexed: 11/21/2022]
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17
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Bertelli DF, Araújo EP, Cesquini M, Stoppa GR, Gasparotto-Contessotto M, Toyama MH, Felix JVC, Carvalheira JB, Michelini LC, Chiavegatto S, Boschero AC, Saad MJA, Lopes-Cendes I, Velloso LA. Phosphoinositide-specific inositol polyphosphate 5-phosphatase IV inhibits inositide trisphosphate accumulation in hypothalamus and regulates food intake and body weight. Endocrinology 2006; 147:5385-99. [PMID: 16916951 DOI: 10.1210/en.2006-0280] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The enzyme phosphatidylinositol 3-kinase (PI3-kinase) exerts an important role in the transduction of the anorexigenic and thermogenic signals delivered by insulin and leptin to first-order neurons of the arcuate nucleus in the hypothalamus. The termination of the intracellular signals generated by the activation of PI3-kinase depends on the coordinated activity of specific inositol phosphatases. Here we show that phosphoinositide-specific inositol polyphosphate 5-phosphatase IV (5ptase IV) is highly expressed in neurons of the arcuate and lateral nuclei of the hypothalamus. Upon intracerebroventricular (ICV) treatment with insulin, 5ptase IV undergoes a time-dependent tyrosine phosphorylation, which follows the same patterns of canonical insulin signaling through the insulin receptor, insulin receptor substrate-2, and PI3-kinase. To evaluate the participation of 5ptase IV in insulin action in hypothalamus, we used a phosphorthioate-modified antisense oligonucleotide specific for this enzyme. The treatment of rats with this oligonucleotide for 4 d reduced the hypothalamic expression of 5ptase IV by approximately 80%. This was accompanied by an approximately 70% reduction of insulin-induced tyrosine phosphorylation of 5ptase IV and an increase in basal accumulation of phosphorylated inositols in the hypothalamus. Finally, inhibition of hypothalamic 5ptase IV expression by the antisense approach resulted in reduced daily food intake and body weight loss. Thus, 5ptase IV is a powerful regulator of signaling through PI3-kinase in hypothalamus and may become an interesting target for therapeutics of obesity and related disorders.
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Affiliation(s)
- Daniela F Bertelli
- Departamento de Clínica Médica, Faculdade de Ciências Medicas, State University of Campinas, 13083-970 Campinas SP, Brazil
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18
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Calegari VC, Alves M, Picardi PK, Inoue RY, Franchini KG, Saad MJA, Velloso LA. Suppressor of cytokine signaling-3 Provides a novel interface in the cross-talk between angiotensin II and insulin signaling systems. Endocrinology 2005; 146:579-88. [PMID: 15514089 DOI: 10.1210/en.2004-0466] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Angiotensin II inhibits insulin-induced activation of phosphatidylinositol 3-kinase through a mechanism, at least in part, dependent on serine phosphorylation of the insulin receptor and insulin receptor substrates (IRS)-1/2. Recent evidence shows that suppressor of cytokine signaling-3 (SOCS-3) is induced by insulin and angiotensin II and participates in the negative control of further stimulation of each of these signaling systems independently. In the present study, we evaluated the interaction of angiotensin II-induced SOCS-3 with the insulin signaling pathway in the heart of living rats. A single iv dose of angiotensin II promotes a significant increase of SOCS-3 in heart, an effect that lasts up to 180 min. Once induced, SOCS-3 interacts with the insulin receptor, JAK-2, IRS-1, and IRS-2. The inhibition of SOCS-3 expression by a phosphorthioate-modified antisense oligonucleotide partially restores angiotensin II-induced inhibition of insulin-induced insulin receptor, IRS-1 and IRS-2 tyrosine phosphorylation, and IRS-1 and IRS-2 association with p85-phosphatidylinositol 3-kinase and [Ser473] phosphorylation of Akt. Moreover, the inhibition of SOCS-3 expression partially reverses angiotensin II-induced inhibition of insulin-stimulated glucose transporter-4 translocation to the cell membrane. These results are reproduced in isolated cardiomyocytes. Thus, SOCS-3 participates, as a late event, in the negative cross-talk between angiotensin II and insulin, producing an inhibitory effect on insulin-induced glucose transporter-4 translocation.
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Affiliation(s)
- Vivian C Calegari
- Department of Internal Medicine, State University of Campinas, 13081-970 Campinas São Paulo, Brazil
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19
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Ferreira F, Barbosa HCL, Stoppiglia LF, Delghingaro-Augusto V, Pereira EA, Boschero AC, Carneiro EM. Decreased insulin secretion in islets from rats fed a low protein diet is associated with a reduced PKAalpha expression. J Nutr 2004; 134:63-7. [PMID: 14704294 DOI: 10.1093/jn/134.1.63] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A low protein diet has been shown to affect the amount and activity of several enzymes and to decrease insulin secretion by islets isolated from rats fed such a diet. To understand the mechanisms involved in this phenomenon, we investigated the effects of forskolin, a stimulator of adenylyl cyclase, on insulin secretion by pancreatic islets from rats fed a normal (17%; NP) or low (6%; LP) protein diet for 8 wk. Isolated islets were incubated for 1 h in Krebs-bicarbonate solution containing 8.3 mmol glucose/L, with or without 10 micromol forskolin/L. The forskolin-induced insulin secretion was higher in islets from NP rats than in those from LP rats (P<0.05). Western blotting revealed that the amount of the alpha catalytic subunit of protein kinase A (PKAalpha) was 35% lower in islets from LP rats than in islets from NP rats (P<0.05). Moreover, PKAalpha mRNA expression was reduced by 30% in islets from LP rats (P<0.05). Our results indicated a possible relationship between a low protein diet and a reduction in PKAalpha expression. These alterations in PKAalpha may be responsible in part for the decreased insulin secretion by islets from rats fed a low protein diet.
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Affiliation(s)
- Fabiano Ferreira
- Departamento de Fisiologia e Biofísica, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, SP, Brazil
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Borelli MI, Francini F, Gagliardino JJ. Autocrine regulation of glucose metabolism in pancreatic islets. Am J Physiol Endocrinol Metab 2004; 286:E111-5. [PMID: 13129856 DOI: 10.1152/ajpendo.00161.2003] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We evaluated the possible autocrine modulatory effect of insulin on glucose metabolism and glucose-induced insulin secretion in islets isolated from normal hamsters. We measured 14CO2 and 3H2O production from d-[U-14C]glucose and d-[5-3H]glucose, respectively, in islets incubated with 0.6, 3.3, 8.3, and 16.7 mM glucose alone or with 5 or 15 mU/ml insulin, anti-insulin guinea pig serum (1:500), 25 microM nifedipine, or 150 nM wortmannin. Insulin release was measured (radioimmunoassay) in islets incubated with 3.3 or 16.7 mM glucose with or without 75, 150, and 300 nM wortmannin. Insulin significantly enhanced 14CO2 and 3H2O production with 3.3 mM glucose but not with 0.6, 8.3, or 16.7 mM glucose. Addition of anti-insulin serum to the medium with 8.3 and 16.7 mM glucose decreased 14CO2 and 3H2O production significantly. A similar decrease was obtained in islets incubated with 8.3 and 16.7 mM glucose and wortmannin or nifedipine. This latter effect was reversed by adding 15 mU/ml insulin to the medium. Glucose metabolism was almost abolished when islets were incubated in a Ca2+-deprived medium, but this effect was not reversed by insulin. No changes were found in 14CO2 and 3H2O production by islets incubated with 3.3 mM glucose and anti-insulin serum, wortmannin, or nifedipine in the media. Addition of wortmannin significantly decreased insulin release induced by 16.7 mM glucose in a dose-dependent manner. Our results suggest that insulin exerts a physiological autocrine stimulatory effect on glucose metabolism in intact islets as well as on glucose-induced insulin release. Such an effect, however, depends on the glucose concentration in the incubation medium.
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Affiliation(s)
- María I Borelli
- CENEXA (UNLP-CONICET), National University of La Plata School of Medicine, Facultad de Ciencias Médicas, Calles 60 y 120, 1900 La Plata, Argentina
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Carvalheira JBC, Ribeiro EB, Araújo EP, Guimarães RB, Telles MM, Torsoni M, Gontijo JAR, Velloso LA, Saad MJA. Selective impairment of insulin signalling in the hypothalamus of obese Zucker rats. Diabetologia 2003; 46:1629-40. [PMID: 14600817 DOI: 10.1007/s00125-003-1246-x] [Citation(s) in RCA: 119] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2003] [Revised: 08/04/2003] [Indexed: 02/07/2023]
Abstract
AIM/HYPOTHESIS By acting in the brain, insulin suppresses food intake. However, little is known with regard to insulin signalling in the hypothalamus in insulin-resistant states. METHODS Western blotting, immunohistochemistry and polymerase chain reaction assays were combined to compare in vivo hypothalamic insulin signalling through the PI3-kinase and MAP kinase pathways between lean and obese Zucker rats. RESULTS Intracerebroventricular insulin infusion reduced food intake in lean rats to a greater extent than that observed in obese rats, and pre-treatment with PI3-kinase inhibitors prevented insulin-induced anorexia. The relative abundance of IRS-2 was considerably higher than that of IRS-1 in hypothalamus of both lean and obese rats. Insulin-stimulated phosphorylation of IR, IRS-1/2, the associations of PI 3-kinase to IRS-1/2 and phosphorylation of Akt in hypothalamus were decreased in obese rats compared to lean rats. These effects seem to be mediated by increased phosphoserine content of IR, IRS-1/2 and decreased protein levels of IRS-1/2 in obese rats. In contrast, insulin stimulated the phosphorylation of MAP kinase equally in lean and obese rats. CONCLUSION/INTERPRETATION This study provides direct measurements of insulin signalling in hypothalamus, and documents selective resistance to insulin signalling in hypothalamus of Zucker rats. These findings provide support for the hypothesis that insulin could have anti-obesity actions mediated by the PI3-kinase pathway, and that impaired insulin signalling in hypothalamus could play a role in the development of obesity in this animal model of insulin-resistance.
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Affiliation(s)
- J B C Carvalheira
- Departamento de Clínica Médica, FCM, Universidade Estadual de Campinas (UNICAMP), 13081-970, Campinas, SP, Brasil
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22
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Pereira-da-Silva M, Torsoni MA, Nourani HV, Augusto VD, Souza CT, Gasparetti AL, Carvalheira JB, Ventrucci G, Marcondes MCCG, Cruz-Neto AP, Saad MJA, Boschero AC, Carneiro EM, Velloso LA. Hypothalamic melanin-concentrating hormone is induced by cold exposure and participates in the control of energy expenditure in rats. Endocrinology 2003; 144:4831-40. [PMID: 12960043 DOI: 10.1210/en.2003-0243] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Short-term cold exposure of homeothermic animals leads to higher thermogenesis and food consumption accompanied by weight loss. An analysis of cDNA-macroarray was employed to identify candidate mRNA species that encode proteins involved in thermogenic adaptation to cold. A cDNA-macroarray analysis, confirmed by RT-PCR, immunoblot, and RIA, revealed that the hypothalamic expression of melanin-concentrating hormone (MCH) is enhanced by exposure of rats to cold environment. The blockade of hypothalamic MCH expression by antisense MCH oligonucleotide in cold-exposed rats promoted no changes in feeding behavior and body temperature. However, MCH blockade led to a significant drop in body weight, which was accompanied by decreased liver glycogen, increased relative body fat, increased absolute and relative interscapular brown adipose tissue mass, increased uncoupling protein 1 expression in brown adipose tissue, and increased consumption of lean body mass. Thus, increased hypothalamic MCH expression in rats exposed to cold may participate in the process that allows for efficient use of energy for heat production during thermogenic adaptation to cold.
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23
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De Souza CT, Gasparetti AL, Pereira-da-Silva M, Araújo EP, Carvalheira JB, Saad MJA, Boschero AC, Carneiro EM, Velloso LA. Peroxisome proliferator-activated receptor gamma coactivator-1-dependent uncoupling protein-2 expression in pancreatic islets of rats: a novel pathway for neural control of insulin secretion. Diabetologia 2003; 46:1522-31. [PMID: 14576981 DOI: 10.1007/s00125-003-1222-5] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2003] [Revised: 07/24/2003] [Indexed: 02/07/2023]
Abstract
AIMS/HYPOTHESIS Sympathetic inputs inhibit insulin secretion through alpha2-adrenergic receptors coupled with Gi protein. High adrenergic tonus generated by exposure of homeothermic animals to cold reduces insulin secretion. In this study we evaluate the participation of UCP-2 in cold-induced regulation of insulin secretion. METHODS Static insulin secretion studies, western blotting and immunohistochemistry were used in this investigation. RESULTS Exposure of rats to cold during 8 days promoted 60% ( n=15, p<0.05) reduction of basal serum insulin levels concentration accompanied by reduction of the area under insulin curve during i.p. GTT (50%, n=15, p<0.05). Isolated islets from cold-exposed rats secreted 57% ( n=6, p<0.05) less insulin following a glucose challenge. Previous sympathectomy, partially prevented the effect of cold exposure upon insulin secretion. Islets isolated from cold-exposed rats expressed 51% ( n=6, p<0.5) more UCP-2 than islets from control rats, while the inhibition of UCP-2 expression by antisense oligonucleotide treatment partially restored insulin secretion of islets obtained from cold-exposed rats. Cold exposure also induced an increase of 69% ( n=6, p<0.05) in PGC-1 protein content in pancreatic islets. Inhibition of islet PGC-1 expression by antisense oligonucleotide abrogated cold-induced UCP-2 expression and partially restored insulin secretion in islets exposed to cold. CONCLUSION/INTERPRETATION Our data indicate that sympathetic tonus generated by exposure of rats to cold induces the expression of PGC-1, which participates in the control of UCP-2 expression in pancreatic islets. Increased UCP-2 expression under these conditions could reduce the beta-cell ATP/ADP ratio and negatively regulate insulin secretion.
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Affiliation(s)
- C T De Souza
- Department of Internal Medicine, State University of Campinas, UNICAMP, Campinas, SP, Brazil
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Gasparetti AL, de Souza CT, Pereira-da-Silva M, Oliveira RLGS, Saad MJA, Carneiro EM, Velloso LA. Cold exposure induces tissue-specific modulation of the insulin-signalling pathway in Rattus norvegicus. J Physiol 2003; 552:149-62. [PMID: 12897167 PMCID: PMC2343313 DOI: 10.1113/jphysiol.2003.050369] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Cold exposure provides a reproducible model of improved glucose turnover accompanied by reduced steady state and glucose-induced insulin levels. In the present report we performed immunoprecipitation and immunoblot studies to evaluate the initial and intermediate steps of the insulin-signalling pathway in white and brown adipose tissues, liver and skeletal muscle of rats exposed to cold. Basal and glucose-induced insulin secretion were significantly impaired, while glucose clearance rates during a glucose tolerance test and the constant for glucose decay during a 15 min insulin tolerance test were increased, indicating a significantly improved glucose turnover and insulin sensitivity in rats exposed to cold. Evaluation of protein levels and insulin-induced tyrosine (insulin receptor, insulin receptor substrates (IRS)-1 and -2, ERK (extracellular signal-related kinase)) or serine (Akt; protein kinase B) phosphorylation of proteins of the insulin signalling cascade revealed a tissue-specific pattern of regulation of the molecular events triggered by insulin such that in white adipose tissue and skeletal muscle an impaired molecular response to insulin was detected, while in brown adipose tissue an enhanced response to insulin was evident. In muscle and white and brown adipose tissues, increased 2-deoxy-D-glucose (2-DG) uptake was detected. Thus, during cold exposure there is a tissue-specific regulation of the insulin-signalling pathway, which seems to favour heat-producing brown adipose tissue. Nevertheless, muscle and white adipose tissue are able to take up large amounts of glucose, even in the face of an apparent molecular resistance to insulin.
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Calegari VC, Bezerra RMN, Torsoni MA, Torsoni AS, Franchini KG, Saad MJA, Velloso LA. Suppressor of cytokine signaling 3 is induced by angiotensin II in heart and isolated cardiomyocytes, and participates in desensitization. Endocrinology 2003; 144:4586-96. [PMID: 12960061 DOI: 10.1210/en.2003-0046] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Angiotensin II (Ang II) exerts a potent growth stimulus on the heart and vascular wall. Activation of the Janus kinase/signal transducer and activator of transcription (JAK/STAT) intracellular signaling pathway by Ang II mediates at least some of the mitogenic responses to this hormone. In other signaling systems that use the JAK/STAT pathway, proteins of the suppressor of cytokine signaling (SOCS) family participate in signal regulation. In the present study it is demonstrated that SOCS3 is constitutively expressed at a low level in rat heart and neonatal rat ventricular myocytes. Ang II at a physiological concentration enhances the expression of SOCS3 mRNA and protein, mainly via AT1 receptors. After induction, SOCS3 associates with JAK2 and impairs further activation of the JAK2/STAT1 pathway. Pretreatment of rats with a specific phosphorthioate antisense oligonucleotide to SOCS3, reverses the desensitization to angiotensin signaling, as detected by a fall in c-Jun expression after repetitive infusions of the hormone. Thus, SOCS3 is induced by Ang II in rat heart and neonatal rat ventricular myocytes and participates in the modulation of the signal generated by this hormone.
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Affiliation(s)
- Vivian C Calegari
- Department of Internal Medicine, State University of Campinas, 13084 970 Campinas SP, Brazil
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26
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Torsoni MA, Carvalheira JB, Pereira-Da-Silva M, de Carvalho-Filho MA, Saad MJA, Velloso LA. Molecular and functional resistance to insulin in hypothalamus of rats exposed to cold. Am J Physiol Endocrinol Metab 2003; 285:E216-23. [PMID: 12644444 DOI: 10.1152/ajpendo.00031.2003] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Insulin and leptin act in the hypothalamus, providing robust anorexigenic signals. The exposure of homeothermic animals to a cold environment leads to increased feeding, accompanied by sustained low levels of insulin and leptin. In the present study, the initial and intermediate steps of the insulin-signaling cascade were evaluated in the hypothalamus of cold-exposed Wistar rats. By immunohistochemistry, most insulin receptor (IR) and insulin receptor substrate-2 (IRS-2) immunoreactivity localized to the arcuate nucleus. Basal levels of tyrosine phosphorylation of IR and IRS-2 were increased in cold-exposed rats compared with rats maintained at room temperature. However, after an acute, peripheral infusion of exogenous insulin, significantly lower increases of IR and IRS-2 tyrosine phosphorylation were detected in the hypothalamus of cold-exposed rats. Insulin-induced association of p85/phosphatidylinositol 3-kinase with IRS-2, Ser473 phosphorylation of Akt, and tyrosine phosphorylation of ERK was significantly reduced in the hypothalamus of cold-exposed rats. To test the hypothesis of functional impairment of insulin signaling in the hypothalamus, intracerebroventricularly cannulated rats were acutely treated with insulin, and food ingestion was measured over a period of 12 h. Cold-exposed animals presented a significantly lower insulin-induced reduction in food consumption compared with animals maintained at room temperature. Hence, the present studies reveal that animals exposed to cold are resistant, both at the molecular and the functional level, to the actions of insulin in the hypothalamus.
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Affiliation(s)
- Márcio A Torsoni
- Department of Internal Medicine, State University of Campinas, Brazil
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