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Roberts A, Phuah P, Cheng S, Murphy KG. Targeting Enteroendocrine Cells to Treat Metabolic Disease. COMPREHENSIVE PHARMACOLOGY 2022:344-372. [DOI: 10.1016/b978-0-12-820472-6.00068-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2025]
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2
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Osinski C, Le Gléau L, Poitou C, de Toro-Martin J, Genser L, Fradet M, Soula HA, Leturque A, Blugeon C, Jourdren L, Hubert EL, Clément K, Serradas P, Ribeiro A. Type 2 diabetes is associated with impaired jejunal enteroendocrine GLP-1 cell lineage in human obesity. Int J Obes (Lond) 2020; 45:170-183. [PMID: 33037328 PMCID: PMC7752761 DOI: 10.1038/s41366-020-00694-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 09/07/2020] [Accepted: 09/26/2020] [Indexed: 12/15/2022]
Abstract
Objectives Altered enteroendocrine cell (EEC) function in obesity and type 2 diabetes is not fully understood. Understanding the transcriptional program that controls EEC differentiation is important because some EEC types harbor significant therapeutic potential for type 2 diabetes. Methods EEC isolation from jejunum of obese individuals with (ObD) or without (Ob) type 2 diabetes was obtained with a new method of cell sorting. EEC transcriptional profiles were established by RNA-sequencing in a first group of 14 Ob and 13 ObD individuals. EEC lineage and densities were studied in the jejunum of a second independent group of 37 Ob, 21 ObD and 22 non obese (NOb) individuals. Results The RNA seq analysis revealed a distinctive transcriptomic signature and a decreased differentiation program in isolated EEC from ObD compared to Ob individuals. In the second independent group of ObD, Ob and NOb individuals a decreased GLP-1 cell lineage and GLP-1 maturation from proglucagon, were observed in ObD compared to Ob individuals. Furthermore, jejunal density of GLP-1-positive cells was significantly reduced in ObD compared to Ob individuals. Conclusions These results highlight that the transcriptomic signature of EEC discriminate obese subjects according to their diabetic status. Furthermore, type 2 diabetes is associated with reduced GLP-1 cell differentiation and proglucagon maturation leading to low GLP-1-cell density in human obesity. These mechanisms could account for the decrease plasma GLP-1 observed in metabolic diseases.
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Affiliation(s)
- Céline Osinski
- Sorbonne Université, INSERM, Nutrition and obesities: systemic approaches, F-75013, Paris, France
| | - Léa Le Gléau
- Sorbonne Université, INSERM, Nutrition and obesities: systemic approaches, F-75013, Paris, France
| | - Christine Poitou
- Sorbonne Université, INSERM, Nutrition and obesities: systemic approaches, F-75013, Paris, France.,Nutrition Department, Pitié-Salpêtrière hospital, Assistance Publique/Hôpitaux de Paris, F-75013, Paris, France
| | - Juan de Toro-Martin
- Sorbonne Université, Université de Paris, INSERM, Cordeliers Research Center, F-75006, Paris, France.,Institute of Nutrition and Functional Foods (INAF), School of Nutrition, Université Laval, Quebec, QC, Canada
| | - Laurent Genser
- Sorbonne Université, INSERM, Nutrition and obesities: systemic approaches, F-75013, Paris, France.,Hepato-Biliary-Pancreatic Gastrointestinal Surgery and Liver Transplantation, Pitié-Salpêtrière Hospital, Assistance Publique/Hôpitaux de Paris, F-75013, Paris, France
| | - Magali Fradet
- Cytometry platform, Institut Cardiometabolism and Nutrition, F-75013, Paris, France.,Institut de Biologie, CIRB, Collège de France, F-75005, Paris, France
| | - Hédi Antoine Soula
- Sorbonne Université, INSERM, Nutrition and obesities: systemic approaches, F-75013, Paris, France
| | - Armelle Leturque
- Sorbonne Université, INSERM, Nutrition and obesities: systemic approaches, F-75013, Paris, France
| | - Corinne Blugeon
- Genomics core facility, Département de biologie, Institut de Biologie de l'ENS (IBENS), École normale supérieure, CNRS, INSERM, Université PSL, 75005, Paris, France
| | - Laurent Jourdren
- Genomics core facility, Département de biologie, Institut de Biologie de l'ENS (IBENS), École normale supérieure, CNRS, INSERM, Université PSL, 75005, Paris, France
| | - Edwige Ludiwyne Hubert
- Sorbonne Université, Université de Paris, INSERM, Cordeliers Research Center, F-75006, Paris, France.,SERVIER, ADIR, F-92284, Suresnes, cedex, France
| | - Karine Clément
- Sorbonne Université, INSERM, Nutrition and obesities: systemic approaches, F-75013, Paris, France.,Nutrition Department, Pitié-Salpêtrière hospital, Assistance Publique/Hôpitaux de Paris, F-75013, Paris, France
| | - Patricia Serradas
- Sorbonne Université, INSERM, Nutrition and obesities: systemic approaches, F-75013, Paris, France.
| | - Agnès Ribeiro
- Sorbonne Université, INSERM, Nutrition and obesities: systemic approaches, F-75013, Paris, France.
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Casanova-Martí À, González-Abuín N, Serrano J, Blay MT, Terra X, Frost G, Pinent M, Ardévol A. Long Term Exposure to a Grape Seed Proanthocyanidin Extract Enhances L-Cell Differentiation in Intestinal Organoids. Mol Nutr Food Res 2020; 64:e2000303. [PMID: 32613679 DOI: 10.1002/mnfr.202000303] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 06/17/2020] [Indexed: 01/08/2023]
Abstract
SCOPE A grape-seed proanthocyanidin extract (GSPE) interacts at the intestinal level, enhancing glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) release, which modulate appetite and glucose homeostasis. Thus, enhancing L-cell numbers could be a strategy to promote hormone production, providing a potential strategy for obesity and type-2 diabetes mellitus (T2DM) treatment. METHODS AND RESULTS Mice ileum organoids are used to evaluate the long-term effects of GSPE and two of its main components, epicatechin (EC) and gallic acid (GA), on intestinal differentiation. Hormone levels are determined using RIA and ELISA kits, and gene expression of transcription factors involved in intestinal cell differentiation, as well as markers of different cell types, are assessed by real-time qPCR. GSPE upregulates enterohormone gene expression and content, as well as the pan-endocrine marker chromogranin A. GSPE also modulates the temporal gene expression profile of early and late transcription factors involved in L-cell differentiation. Furthermore, GSPE upregulates goblet cell (Muc2) and enterocyte (sucraseisomaltase) markers, while downregulating stem cell markers (Lgr5+). Although EC and GA modified enterohormone release, they do not reproduce GSPE effects on transcription factor's profile. CONCLUSIONS This study shows the potential role of GSPE in promoting enteroendocrine differentiation, effect that is not mediated by EC or GA.
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Affiliation(s)
- Àngela Casanova-Martí
- MoBioFood Research Group, Departament de Bioquímica i Biotecnologia, Universitat Rovira i Virgili, C/Marcel·li Domingo 1, Tarragona, 43007, Spain
| | - Noemi González-Abuín
- Section for Nutrition Research, Department of Metabolism, Digestion, and Reproduction, Hammersmith Hospital, Imperial College London, London, W12 0NN, UK
| | - Joan Serrano
- MoBioFood Research Group, Departament de Bioquímica i Biotecnologia, Universitat Rovira i Virgili, C/Marcel·li Domingo 1, Tarragona, 43007, Spain
| | - Maria Teresa Blay
- MoBioFood Research Group, Departament de Bioquímica i Biotecnologia, Universitat Rovira i Virgili, C/Marcel·li Domingo 1, Tarragona, 43007, Spain
| | - Ximena Terra
- MoBioFood Research Group, Departament de Bioquímica i Biotecnologia, Universitat Rovira i Virgili, C/Marcel·li Domingo 1, Tarragona, 43007, Spain
| | - Gary Frost
- Section for Nutrition Research, Department of Metabolism, Digestion, and Reproduction, Hammersmith Hospital, Imperial College London, London, W12 0NN, UK
| | - Montserrat Pinent
- MoBioFood Research Group, Departament de Bioquímica i Biotecnologia, Universitat Rovira i Virgili, C/Marcel·li Domingo 1, Tarragona, 43007, Spain
| | - Anna Ardévol
- MoBioFood Research Group, Departament de Bioquímica i Biotecnologia, Universitat Rovira i Virgili, C/Marcel·li Domingo 1, Tarragona, 43007, Spain
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4
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Lang S, Yang J, Yang K, Gu L, Cui X, Wei T, Liu J, Le Y, Wang H, Wei R, Hong T. Glucagon receptor antagonist upregulates circulating GLP-1 level by promoting intestinal L-cell proliferation and GLP-1 production in type 2 diabetes. BMJ Open Diabetes Res Care 2020; 8:8/1/e001025. [PMID: 32139602 PMCID: PMC7059498 DOI: 10.1136/bmjdrc-2019-001025] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Revised: 01/24/2020] [Accepted: 01/26/2020] [Indexed: 02/06/2023] Open
Abstract
OBJECTIVE Glucagon receptor (GCGR) blockage improves glycemic control and increases circulating glucagon-like peptide-1 (GLP-1) level in diabetic animals and humans. The elevated GLP-1 has been reported to be involved in the hypoglycemic effect of GCGR blockage. However, the source of this elevation remains to be clarified. RESEARCH DESIGN AND METHODS REMD 2.59, a human GCGR monoclonal antibody (mAb), was administrated for 12 weeks in db/db mice and high-fat diet+streptozotocin (HFD/STZ)-induced type 2 diabetic (T2D) mice. Blood glucose, glucose tolerance and plasma GLP-1 were evaluated during the treatment. The gut length, epithelial area, and L-cell number and proliferation were detected after the mice were sacrificed. Cell proliferation and GLP-1 production were measured in mouse L-cell line GLUTag cells, and primary mouse and human enterocytes. Moreover, GLP-1 receptor (GLP-1R) antagonist or protein kinase A (PKA) inhibitor was used in GLUTag cells to determine the involved signaling pathways. RESULTS Treatment with the GCGR mAb lowered blood glucose level, improved glucose tolerance and elevated plasma GLP-1 level in both db/db and HFD/STZ-induced T2D mice. Besides, the treatment promoted L-cell proliferation and LK-cell expansion, and increased the gut length, epithelial area and L-cell number in these two T2D mice. Similarly, our in vitro study showed that the GCGR mAb promoted L-cell proliferation and increased GLP-1 production in GLUTag cells, and primary mouse and human enterocytes. Furthermore, either GLP-1R antagonist or PKA inhibitor diminished the effects of GCGR mAb on L-cell proliferation and GLP-1 production. CONCLUSIONS The elevated circulating GLP-1 level by GCGR mAb is mainly due to intestinal L-cell proliferation and GLP-1 production, which may be mediated via GLP-1R/PKA signaling pathways. Therefore, GCGR mAb represents a promising strategy to improve glycemic control and restore the impaired GLP-1 production in T2D.
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Affiliation(s)
- Shan Lang
- Department of Endocrinology and Metabolism, Peking University Third Hospital, Beijing, China
- Clinical Stem Cell Research Center, Peking University Third Hospital, Beijing, China
| | - Jin Yang
- Department of Endocrinology and Metabolism, Peking University Third Hospital, Beijing, China
| | - Kun Yang
- Department of Endocrinology and Metabolism, Peking University Third Hospital, Beijing, China
| | - Liangbiao Gu
- Department of Endocrinology and Metabolism, Peking University Third Hospital, Beijing, China
- Clinical Stem Cell Research Center, Peking University Third Hospital, Beijing, China
| | - Xiaona Cui
- Department of Endocrinology and Metabolism, Peking University Third Hospital, Beijing, China
- Clinical Stem Cell Research Center, Peking University Third Hospital, Beijing, China
| | - Tianjiao Wei
- Department of Endocrinology and Metabolism, Peking University Third Hospital, Beijing, China
- Clinical Stem Cell Research Center, Peking University Third Hospital, Beijing, China
| | - Junling Liu
- Department of Endocrinology and Metabolism, Peking University Third Hospital, Beijing, China
| | - Yunyi Le
- Department of Endocrinology and Metabolism, Peking University Third Hospital, Beijing, China
| | - Haining Wang
- Department of Endocrinology and Metabolism, Peking University Third Hospital, Beijing, China
| | - Rui Wei
- Department of Endocrinology and Metabolism, Peking University Third Hospital, Beijing, China
- Clinical Stem Cell Research Center, Peking University Third Hospital, Beijing, China
| | - Tianpei Hong
- Department of Endocrinology and Metabolism, Peking University Third Hospital, Beijing, China
- Clinical Stem Cell Research Center, Peking University Third Hospital, Beijing, China
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Müller TD, Finan B, Bloom SR, D'Alessio D, Drucker DJ, Flatt PR, Fritsche A, Gribble F, Grill HJ, Habener JF, Holst JJ, Langhans W, Meier JJ, Nauck MA, Perez-Tilve D, Pocai A, Reimann F, Sandoval DA, Schwartz TW, Seeley RJ, Stemmer K, Tang-Christensen M, Woods SC, DiMarchi RD, Tschöp MH. Glucagon-like peptide 1 (GLP-1). Mol Metab 2019; 30:72-130. [PMID: 31767182 PMCID: PMC6812410 DOI: 10.1016/j.molmet.2019.09.010] [Citation(s) in RCA: 1041] [Impact Index Per Article: 173.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 09/10/2019] [Accepted: 09/22/2019] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND The glucagon-like peptide-1 (GLP-1) is a multifaceted hormone with broad pharmacological potential. Among the numerous metabolic effects of GLP-1 are the glucose-dependent stimulation of insulin secretion, decrease of gastric emptying, inhibition of food intake, increase of natriuresis and diuresis, and modulation of rodent β-cell proliferation. GLP-1 also has cardio- and neuroprotective effects, decreases inflammation and apoptosis, and has implications for learning and memory, reward behavior, and palatability. Biochemically modified for enhanced potency and sustained action, GLP-1 receptor agonists are successfully in clinical use for the treatment of type-2 diabetes, and several GLP-1-based pharmacotherapies are in clinical evaluation for the treatment of obesity. SCOPE OF REVIEW In this review, we provide a detailed overview on the multifaceted nature of GLP-1 and its pharmacology and discuss its therapeutic implications on various diseases. MAJOR CONCLUSIONS Since its discovery, GLP-1 has emerged as a pleiotropic hormone with a myriad of metabolic functions that go well beyond its classical identification as an incretin hormone. The numerous beneficial effects of GLP-1 render this hormone an interesting candidate for the development of pharmacotherapies to treat obesity, diabetes, and neurodegenerative disorders.
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Affiliation(s)
- T D Müller
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany; Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics, Tübingen, Germany.
| | - B Finan
- Novo Nordisk Research Center Indianapolis, Indianapolis, IN, USA
| | - S R Bloom
- Division of Diabetes, Endocrinology and Metabolism, Imperial College London, London, UK
| | - D D'Alessio
- Division of Endocrinology, Duke University Medical Center, Durham, NC, USA
| | - D J Drucker
- The Department of Medicine, Lunenfeld-Tanenbaum Research Institute, Mt. Sinai Hospital, University of Toronto, Ontario, M5G1X5, Canada
| | - P R Flatt
- SAAD Centre for Pharmacy & Diabetes, Ulster University, Coleraine, Northern Ireland, UK
| | - A Fritsche
- German Center for Diabetes Research (DZD), Neuherberg, Germany; Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany; Division of Endocrinology, Diabetology, Vascular Disease, Nephrology and Clinical Chemistry, Department of Internal Medicine, University of Tübingen, Tübingen, Germany
| | - F Gribble
- Metabolic Research Laboratories and Medical Research Council Metabolic Diseases Unit, Wellcome Trust-Medical Research Council, Institute of Metabolic Science, Addenbrooke's Hospital, University of Cambridge, Cambridge, CB2 0QQ, UK
| | - H J Grill
- Institute of Diabetes, Obesity and Metabolism, Department of Psychology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - J F Habener
- Laboratory of Molecular Endocrinology, Massachusetts General Hospital, Harvard University, Boston, MA, USA
| | - J J Holst
- Novo Nordisk Foundation Center for Basic Metabolic Research, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - W Langhans
- Physiology and Behavior Laboratory, ETH Zurich, Schwerzenbach, Switzerland
| | - J J Meier
- Diabetes Division, St Josef Hospital, Ruhr-University Bochum, Bochum, Germany
| | - M A Nauck
- Diabetes Center Bochum-Hattingen, St Josef Hospital (Ruhr-Universität Bochum), Bochum, Germany
| | - D Perez-Tilve
- Department of Internal Medicine, University of Cincinnati-College of Medicine, Cincinnati, OH, USA
| | - A Pocai
- Cardiovascular & ImmunoMetabolism, Janssen Research & Development, Welsh and McKean Roads, Spring House, PA, 19477, USA
| | - F Reimann
- Metabolic Research Laboratories and Medical Research Council Metabolic Diseases Unit, Wellcome Trust-Medical Research Council, Institute of Metabolic Science, Addenbrooke's Hospital, University of Cambridge, Cambridge, CB2 0QQ, UK
| | - D A Sandoval
- Department of Surgery, University of Michigan Medical School, Ann Arbor, MI, USA
| | - T W Schwartz
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, DL-2200, Copenhagen, Denmark; Department of Biomedical Sciences, University of Copenhagen, DK-2200, Copenhagen, Denmark
| | - R J Seeley
- Department of Surgery, University of Michigan Medical School, Ann Arbor, MI, USA
| | - K Stemmer
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - M Tang-Christensen
- Obesity Research, Global Drug Discovery, Novo Nordisk A/S, Måløv, Denmark
| | - S C Woods
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Cincinnati, OH, USA
| | - R D DiMarchi
- Novo Nordisk Research Center Indianapolis, Indianapolis, IN, USA; Department of Chemistry, Indiana University, Bloomington, IN, USA
| | - M H Tschöp
- German Center for Diabetes Research (DZD), Neuherberg, Germany; Division of Metabolic Diseases, Department of Medicine, Technische Universität München, Munich, Germany; Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany
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Worthington JJ, Reimann F, Gribble FM. Enteroendocrine cells-sensory sentinels of the intestinal environment and orchestrators of mucosal immunity. Mucosal Immunol 2018; 11:3-20. [PMID: 28853441 DOI: 10.1038/mi.2017.73] [Citation(s) in RCA: 162] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 07/14/2017] [Indexed: 02/06/2023]
Abstract
The intestinal epithelium must balance efficient absorption of nutrients with partitioning commensals and pathogens from the bodies' largest immune system. If this crucial barrier fails, inappropriate immune responses can result in inflammatory bowel disease or chronic infection. Enteroendocrine cells represent 1% of this epithelium and have classically been studied for their detection of nutrients and release of peptide hormones to mediate digestion. Intriguingly, enteroendocrine cells are the key sensors of microbial metabolites, can release cytokines in response to pathogen associated molecules and peptide hormone receptors are expressed on numerous intestinal immune cells; thus enteroendocrine cells are uniquely equipped to be crucial and novel orchestrators of intestinal inflammation. In this review, we introduce enteroendocrine chemosensory roles, summarize studies correlating enteroendocrine perturbations with intestinal inflammation and describe the mechanistic interactions by which enteroendocrine and mucosal immune cells interact during disease; highlighting this immunoendocrine axis as a key aspect of innate immunity.
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Affiliation(s)
- J J Worthington
- Lancaster University, Faculty of Health and Medicine, Division of Biomedical and Life Sciences, Lancaster, Lancashire, UK
| | - F Reimann
- University of Cambridge, Metabolic Research Laboratories, Wellcome Trust/MRC Institute of Metabolic Science & MRC Metabolic Diseases Unit, Addenbrooke's Hospital, Cambridge, UK
| | - F M Gribble
- University of Cambridge, Metabolic Research Laboratories, Wellcome Trust/MRC Institute of Metabolic Science & MRC Metabolic Diseases Unit, Addenbrooke's Hospital, Cambridge, UK
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7
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Suzuki K, Iwasaki K, Murata Y, Harada N, Yamane S, Hamasaki A, Shibue K, Joo E, Sankoda A, Fujiwara Y, Hayashi Y, Inagaki N. Distribution and hormonal characterization of primary murine L cells throughout the gastrointestinal tract. J Diabetes Investig 2017; 9:25-32. [PMID: 28429513 PMCID: PMC5754545 DOI: 10.1111/jdi.12681] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 03/24/2016] [Accepted: 04/12/2017] [Indexed: 12/12/2022] Open
Abstract
Aims/Introduction Glucagon‐like peptide‐1 (GLP‐1) secreted from enteroendocrine L cells is an incretin that potentiates insulin secretion and is already applied in therapies for type 2 diabetes. However, detailed examination of L cells throughout the gastrointestinal tract remains unclear, because of difficulties in purifying scattered L cells from other cells. In the present study, we identified characteristics of L cells of the upper small intestine (UI), the lower small intestine (LI) and the colon using glucagon‐green fluorescent protein‐expressing mice that express GFP driven by the proglucagon promoter. Materials and Methods The localization and density of primary L cells were evaluated by anti‐green fluorescent protein antibody reactivity. GLP‐1 content, messenger ribonucleic acid (mRNA) expression levels and secretion in purified L cells were measured. Results The number of L cells significantly increased toward the colon. In contrast, the GLP‐1 content and secretion from L cells were higher in the UI than in the LI and colon. L cells from the UI and LI expressed notably high mRNA levels of the transcription factor, islet 1. The mRNA expression levels of peptide YY in L cells were higher in the LI than in the UI and colon. The mRNA expression levels of gastric inhibitory polypeptide in L cells from the UI were significantly higher compared with those from the LI and colon. Conclusions L cells show different numbers and characteristics throughout the gut, and they express different mRNA levels of transcription factors and gastrointestinal hormones. These results contribute to the therapeutic application of promoting GLP‐1 release from L cells for the treatment of type 2 diabetes.
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Affiliation(s)
- Kazuyo Suzuki
- Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Kanako Iwasaki
- Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Yuki Murata
- Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Norio Harada
- Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Shunsuke Yamane
- Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Akihiro Hamasaki
- Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Kimitaka Shibue
- Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Erina Joo
- Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Akiko Sankoda
- Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Yuta Fujiwara
- Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Yoshitaka Hayashi
- Department of Genetics, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
| | - Nobuya Inagaki
- Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, Kyoto, Japan
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Eda H, Fukui H, Uchiyama R, Kitayama Y, Hara K, Yang M, Kodani M, Tomita T, Oshima T, Watari J, Tsutsui H, Miwa H. Effect of Helicobacter pylori infection on the link between GLP-1 expression and motility of the gastrointestinal tract. PLoS One 2017; 12:e0177232. [PMID: 28545056 PMCID: PMC5436696 DOI: 10.1371/journal.pone.0177232] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2017] [Accepted: 04/24/2017] [Indexed: 12/12/2022] Open
Abstract
Background Although Helicobacter pylori (H. pylori) infection is closely associated with the development of peptic ulcer, its involvement in pathophysiology in the lower intestinal tract and gastrointestinal (GI) motility remains unclear. Glucagon-like peptide-1 (GLP-1) is a gut hormone produced in the lower intestinal tract and involved in GI motility. Here, we investigated the effect of H. pylori infection on the link between GLP-1 expression and motility of the GI tract. Methods C57BL/6 mice were inoculated with a H. pylori strain. Twelve weeks later, the H. pylori-infected mice underwent H. pylori eradication treatment. GI tissues were obtained from the mice at various time intervals, and evaluated for the severity of gastric inflammatory cell infiltration and immunohistochemical expression of GLP-1 and PAX6 in the colonic mucosa. Gastrointestinal transit time (GITT) was measured by administration of carmine-red solution. Results GLP-1 was expressed in the endocrine cells of the colonic mucosa, and PAX6 immunoreactivity was co-localized in such cells. The numbers of GLP-1- and PAX6-positive cells in the colon were significantly increased at 12 weeks after H. pylori infection and showed a positive correlation with each other. The GITT was significantly longer in H. pylori-infected mice than in non-infected controls and showed a positive correlation with GLP-1 expression. When H. pylori-infected mice underwent H. pylori eradication, GITT and PAX6/GLP-1 expression did not differ significantly from those in untreated H. pylori-infected mice. Conclusions H. pylori infection may impair GI motility by enhancing the colonic GLP-1/PAX6 expression.
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Affiliation(s)
- Hirotsugu Eda
- Division of Gastroenterology, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan
| | - Hirokazu Fukui
- Division of Gastroenterology, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan
- * E-mail:
| | - Ryosuke Uchiyama
- Department of Microbiology, Hyogo College of Medicine, Nishinomiya, Japan
| | - Yoshitaka Kitayama
- Division of Gastroenterology, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan
| | - Ken Hara
- Division of Gastroenterology, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan
| | - Mo Yang
- Division of Gastroenterology, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan
- Department of Digestive Diseases, Tianjin Medical University General Hospital, Tianjin, China
| | - Mio Kodani
- Division of Gastroenterology, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan
| | - Toshihiko Tomita
- Division of Gastroenterology, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan
| | - Tadayuki Oshima
- Division of Gastroenterology, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan
| | - Jiro Watari
- Division of Gastroenterology, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan
| | - Hiroko Tsutsui
- Department of Microbiology, Hyogo College of Medicine, Nishinomiya, Japan
| | - Hiroto Miwa
- Division of Gastroenterology, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan
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Connor EE, Evock-Clover CM, Wall EH, Baldwin RL, Santin-Duran M, Elsasser TH, Bravo DM. Glucagon-like peptide 2 and its beneficial effects on gut function and health in production animals. Domest Anim Endocrinol 2016; 56 Suppl:S56-65. [PMID: 27345324 DOI: 10.1016/j.domaniend.2015.11.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Revised: 11/17/2015] [Accepted: 11/26/2015] [Indexed: 12/12/2022]
Abstract
Numerous endocrine cell subtypes exist within the intestinal mucosa and produce peptides contributing to the regulation of critical physiological processes including appetite, energy metabolism, gut function, and gut health. The mechanisms of action and the extent of the physiological effects of these enteric peptides are only beginning to be uncovered. One peptide in particular, glucagon-like peptide 2 (GLP-2) produced by enteroendocrine L cells, has been fairly well characterized in rodent and swine models in terms of its ability to improve nutrient absorption and healing of the gut after injury. In fact, a long-acting form of GLP-2 recently has been approved for the management and treatment of human conditions like inflammatory bowel disease and short bowel syndrome. However, novel functions of GLP-2 within the gut continue to be demonstrated, including its beneficial effects on intestinal barrier function and reducing intestinal inflammation. As knowledge continues to grow about GLP-2's effects on the gut and its mechanisms of release, the potential to use GLP-2 to improve gut function and health of food animals becomes increasingly more apparent. Thus, the purpose of this review is to summarize: (1) the current understanding of GLP-2's functions and mechanisms of action within the gut; (2) novel applications of GLP-2 (or stimulators of its release) to improve general health and production performance of food animals; and (3) recent findings, using dairy calves as a model, that suggest the therapeutic potential of GLP-2 to reduce the pathogenesis of intestinal protozoan infections.
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Affiliation(s)
- E E Connor
- US Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Beltsville, MD 20705 USA.
| | - C M Evock-Clover
- US Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Beltsville, MD 20705 USA
| | - E H Wall
- Pancosma S.A., CH-1218 Geneva, Switzerland
| | - R L Baldwin
- US Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Beltsville, MD 20705 USA
| | - M Santin-Duran
- US Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Beltsville, MD 20705 USA
| | - T H Elsasser
- US Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Beltsville, MD 20705 USA
| | - D M Bravo
- Pancosma S.A., CH-1218 Geneva, Switzerland
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10
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Abstract
Glucagon-like peptide-1 (GLP-1) is a peptide hormone, released from intestinal L-cells in response to hormonal, neural and nutrient stimuli. In addition to potentiation of meal-stimulated insulin secretion, GLP-1 signalling exerts numerous pleiotropic effects on various tissues, regulating energy absorption and disposal, as well as cell proliferation and survival. In Type 2 Diabetes (T2D) reduced plasma levels of GLP-1 have been observed, and plasma levels of GLP-1, as well as reduced numbers of GLP-1 producing cells, have been correlated to obesity and insulin resistance. Increasing endogenous secretion of GLP-1 by selective targeting of the molecular mechanisms regulating secretion from the L-cell has been the focus of much recent research. An additional and promising strategy for enhancing endogenous secretion may be to increase the L-cell mass in the intestinal epithelium, but the mechanisms that regulate the growth, survival and function of these cells are largely unknown. We recently showed that prolonged exposure to high concentrations of the fatty acid palmitate induced lipotoxic effects, similar to those operative in insulin-producing cells, in an in vitro model of GLP-1-producing cells. The mechanisms inducing this lipototoxicity involved increased production of reactive oxygen species (ROS). In this review, regulation of GLP-1-secreting cells is discussed, with a focus on the mechanisms underlying GLP-1 secretion, long-term regulation of growth, differentiation and survival under normal as well as diabetic conditions of hypernutrition.
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Sato T, Hayashi H, Hiratsuka M, Hirasawa N. Glucocorticoids decrease the production of glucagon-like peptide-1 at the transcriptional level in intestinal L-cells. Mol Cell Endocrinol 2015; 406:60-7. [PMID: 25700603 DOI: 10.1016/j.mce.2015.02.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Revised: 01/13/2015] [Accepted: 02/13/2015] [Indexed: 01/28/2023]
Abstract
Glucocorticoids are widely used as anti-inflammatory or immunosuppressive drugs, but often induce hyperglycemia as a side effect. Glucagon-like peptide-1 (GLP-1) is secreted from intestinal L cells and plays crucial roles in maintaining glucose homeostasis. However, the direct effects of glucocorticoids on the GLP-1 production pathway in L cells remain unclear. We investigated the effects of glucocorticoids on GLP-1 production in vitro and in vivo. In L cell lines, glucocorticoids decreased GLP-1 release and expression of the precursor, proglucagon, at protein and mRNA levels, which were inhibited by mifepristone. The administration of dexamethasone or budesonide to mice significantly decreased the mRNA expression of proglucagon in the ileum and partially decreased glucose-stimulated GLP-1 secretion. Compound A, a dissociated glucocorticoid receptor modulator, did not affect the expression of proglucagon in vitro. These results suggested that glucocorticoids directly reduced GLP-1 production at the transcriptional level in L cells through a glucocorticoid receptor dimerization-dependent mechanism.
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Affiliation(s)
- Taiki Sato
- Laboratory of Pharmacotherapy of Life-Style Related Diseases, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan
| | - Hiroto Hayashi
- Laboratory of Pharmacotherapy of Life-Style Related Diseases, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan
| | - Masahiro Hiratsuka
- Laboratory of Pharmacotherapy of Life-Style Related Diseases, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan
| | - Noriyasu Hirasawa
- Laboratory of Pharmacotherapy of Life-Style Related Diseases, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan.
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12
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Yamato E, Bamba Y, Kamiya Y, Yagi K, Miyazaki JI. Analysis of the transcription factor cascade that induces endocrine and exocrine cell lineages from pancreatic progenitor cells using a polyoma-based episomal vector system. J Diabetes Investig 2014; 3:41-51. [PMID: 24843545 PMCID: PMC4014932 DOI: 10.1111/j.2040-1124.2011.00136.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
Aims/Introduction: We recently established a strategy for isolating multipotential duct‐like cells, called pdx‐1‐positive pancreatic cell‐derived (PPPD) cells, from the pancreas. To analyze the molecular mechanisms of pancreatic cell differentiation, we introduced a polyoma‐based episomal vector system into PPPD cells. Materials and Methods: PPPD cells were stably transfected with a polyoma large T (PLT)‐expressing plasmid vector, which included the polyoma origin of replication, to generate PLT‐PPPD cells. Various cDNA for pancreas‐related transcription factors were subcloned into the expression plasmid pPyCAG, which included the polyoma origin of replication. PLT‐PPPD cells were stably transfected with the resulting plasmid vectors and then subjected to gene and protein expression analyses. Results: The coexpression of Mafa, Neurod1 and Ipf1 induced Ins1 and Ins2 expression in PLT‐PPPD cells. The forced expression of Pax6 alone induced the expression of glucagon. The coexpression of Neurod1 and Isl1 induced Ins2 and Sst expression. In contrast, the expression of Ptf1a and Foxa2 induced the expression of exocrine markers Cpa1 and Amy2. Transfections with multiple transcription factors showed that Isl1 is required for the differentiation of both insulin‐positive cells and somatostatin‐positive cells. In addition, Foxa2 induced the differentiation of glucagon‐positive cells and inhibited the differentiation of insulin‐positive and somatostatin‐positive cells. PLT‐PPPD cells allow episomal vector‐based gene expression and should be useful for studying the transcription factor cascades involved in the differentiation of pancreatic cell types in vitro. Conclusions: Our coexpression study showed novel critical roles for Isl1 and Foxa2 in the differentiation of PPPD cells into endocrine cells. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2011.00136.x, 2012)
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Affiliation(s)
- Eiji Yamato
- Stem Cell Regulation Research, Osaka University Graduate School of Medicine
| | - Yohei Bamba
- Stem Cell Regulation Research, Osaka University Graduate School of Medicine
| | - Yukimasa Kamiya
- Stem Cell Regulation Research, Osaka University Graduate School of Medicine ; Bio-functional Molecular Chemistry, Osaka University Graduate School of Pharmaceutical Sciences, Suita, Japan
| | - Kiyohito Yagi
- Bio-functional Molecular Chemistry, Osaka University Graduate School of Pharmaceutical Sciences, Suita, Japan
| | - Jun-Ichi Miyazaki
- Stem Cell Regulation Research, Osaka University Graduate School of Medicine
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13
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Marathe CS, Rayner CK, Jones KL, Horowitz M. Glucagon-like peptides 1 and 2 in health and disease: a review. Peptides 2013; 44:75-86. [PMID: 23523778 DOI: 10.1016/j.peptides.2013.01.014] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Revised: 01/30/2013] [Accepted: 01/30/2013] [Indexed: 02/07/2023]
Abstract
The gut derived peptides, glucagon-like peptides 1 and 2 (GLP-1 and GLP-2), are secreted following nutrient ingestion. GLP-1 and another gut peptide, glucose-dependent insulinotropic polypeptide (GIP) are collectively referred to as 'incretin' hormones, and play an important role in glucose homeostasis. Incretin secretion shares a complex interdependent relationship with both postprandial glycemia and the rate of gastric emptying. GLP-1 based therapies are now well established in the management of type 2 diabetes, while recent literature has suggested potential applications to treat obesity and protect against cardiovascular and neurological disease. The mechanism of action of GLP-2 is not well understood, but it shows promise as an intestinotropic agent.
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Affiliation(s)
- Chinmay S Marathe
- Discipline of Medicine, University of Adelaide, Royal Adelaide Hospital, Adelaide, Australia.
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14
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Grigoryan M, Kedees MH, Charron MJ, Guz Y, Teitelman G. Regulation of mouse intestinal L cell progenitors proliferation by the glucagon family of peptides. Endocrinology 2012; 153:3076-88. [PMID: 22569789 PMCID: PMC3380309 DOI: 10.1210/en.2012-1120] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Glucagon like peptide-1 (GLP-1) and GLP-2 are hormones secreted by intestinal L cells that stimulate glucose-dependent insulin secretion and regulate intestinal growth, respectively. Mice with deletion of the glucagon receptor (Gcgr) have high levels of circulating GLP-1 and GLP-2. We sought to determine whether the increased level of the glucagon-like peptides is due to L cell hyperplasia. We found, first, that high levels of the glucagon-like peptides increase L cell number but does not affect the number of other intestinal epithelial cell types. Second, a large proportion of ileal L cells of Gcgr(-/-) mice coexpressed glucose-dependent insulinotropic peptide (GIP). Cells coexpressing GIP and GLP-1 are termed LK cells. Third, the augmentation in L cell number was due to a higher rate of proliferation of L cell progenitors rather than to the entrance of mature L cells into the cell cycle. Fourth, a high concentration of the glucagon-like peptides in the circulation augmented the mRNA levels of transcription factors expressed by late but not early enteroendocrine progenitors. Fifth, the administration of exendin 9-39, a GLP-1 receptor antagonist, resulted in a decrease in the rate of L cell precursor proliferation. Finally, we determined that L cells do not express the GLP-1 receptor, suggesting that the effect of GLP-1 is mediated by paracrine and/or neuronal signals. Our results suggest that GLP-1 plays an important role in the regulation of L cell number.
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Affiliation(s)
- Marine Grigoryan
- Department of Cell Biology, State University of New York-Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, New York 11203, USA
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15
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Nakashima K, Shimoda M, Hamamoto S, Tatsumi F, Hirukawa H, Tawaramoto K, Kanda Y, Kaku K. Self-inducible secretion of glucagon-like peptide-1 (GLP-1) that allows MIN6 cells to maintain insulin secretion and insure cell survival. Mol Cell Endocrinol 2012; 349:281-8. [PMID: 22108438 DOI: 10.1016/j.mce.2011.11.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2011] [Revised: 09/30/2011] [Accepted: 11/08/2011] [Indexed: 12/25/2022]
Abstract
Based on the hypothesis that MIN6 cells could produce glucagon-like peptide-1 (GLP-1) to maintain cell survival, we analyzed the effects of GLP-1 receptor agonist, exendin-4 (Ex4), and antagonist, exendin-(9-39) (Ex9) on cell function and cell differentiation. MIN6 cells expressed proglucagon mRNAs and produced GLP-1, which was accelerated by Ex4 and suppressed by Ex9. Moreover, Ex4 further enhanced glucose-stimulated GLP-1 secretion, suggesting autocrine loop-contributed amplification of the GLP-1 signal. Ex4 up-regulated cell differentiation- and cell function-related CREBBP, Pdx-1, Pax6, proglucagon, and PC1/3 gene expressions. The confocal laser scanning images revealed that GLP-1 positive cells were dominant in the early stage of cells, but positive for insulin were more prominent in the mature stage of cells. Ex4 accelerated cell viability, while Ex9 and anti-GLP-1 receptor antibody enhanced cell apoptosis. MIN6 cells possess a mechanism of GLP-1 signal amplification in an autocrine fashion, by which the cells maintained insulin production and cell survival.
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Affiliation(s)
- Koji Nakashima
- Division of Diabetes, Endocrinology and Metabolism, Department of Internal Medicine, Kawasaki Medical School, 577 Matsushima, Kurashiki, Okayama 701-0192, Japan
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16
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Wang PX, Yu ZW, Wong S, Jin TR. Nkx6.2 synergizes with Cdx-2 in stimulating proglucagon gene expression. World J Diabetes 2011; 2:66-74. [PMID: 21691557 PMCID: PMC3116010 DOI: 10.4239/wjd.v2.i5.66] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Revised: 04/11/2011] [Accepted: 04/18/2011] [Indexed: 02/05/2023] Open
Abstract
AIM: To investigate whether the transactivator of the proglucagon gene (Gcg), Cdx-2, synergizes with other transcription factors in stimulating Gcg expression and the trans-differentiation of Gcg-expressing cells.
METHODS: We conducted affinity chromatography to identify proteins that interact with Cdx-2, using GST-tagged Cdx-2 against cell lysates from pancreatic InR1-G9 and intestinal GLUTag cell lines. This was followed by a mass-spectrometry analysis. From a potential Cdx-2 interaction protein identified, we examined its expression in pancreatic and gut endocrine cells, confirmed its interaction with Cdx-2 by GST-pull down and determined its effect in provoking Gcg expression in cell lines that do not express endogenous Gcg.
RESULTS: We identified 18 potential Cdx-2 interacting proteins. One of them is Nkx6.2. This homeodomain (HD) protein is expressed in pancreatic α and intestinal endocrine L cells but not in insulin producing cell lines, including In111. Nkx6.2, but not Nkx6.1, was shown to interact with Cdx-2, detected by GST-pull down. Furthermore, Nkx6.2 was found to synergize with Cdx-2 in provoking Gcg expression when they were ectopically expressed in the In111 cell line. Finally, when Cdx-2 and Nkx6.2 were co-transfected into the undifferentiated rat intestinal IEC-6 cell line, it produced detectable amount of Gcg mRNA.
CONCLUSION: Cdx-2 recruits Nkx6.2 in exerting its effect in stimulating Gcg expression. Our observations further support the notion that multiple HD proteins, including Cdx-2 and Nkx6.2, are involved in the regulation of Gcg expression and the genesis of Gcg-producing cells.
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Affiliation(s)
- Pei-Xiang Wang
- Pei-Xiang Wang, Zhi-Wen Yu, Tian-Ru Jin, Department of Nutrition, School of Public Health, Sun Yat-sen University, Guangzhou 510080, Guangdong Province, China
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17
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Iakoubov R, Ahmed A, Lauffer LM, Bazinet RP, Brubaker PL. Essential role for protein kinase Cζ in oleic acid-induced glucagon-like peptide-1 secretion in vivo in the rat. Endocrinology 2011; 152:1244-52. [PMID: 21325047 DOI: 10.1210/en.2010-1352] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Luminal monounsaturated long-chain fatty acids [e.g. oleic acid (OA)] increase secretion of the incretin, glucagon-like peptide-1 (GLP-1) from the ileocolonic L cell. However, it is not known whether OA ingestion causes a sufficient increase in distal luminal concentrations to directly enhance GLP-1 secretion. Furthermore, we have demonstrated that protein kinase Cζ (PKCζ) is required for OA-induced GLP-1 secretion in vitro; however, the physiological relevance of this finding remains unknown. Therefore, we have determined luminal OA concentrations in OA-fed rats and examined the effects of direct OA stimulation on GLP-1 secretion using a novel model of intestinal-specific PKCζ knockdown. Murine GLUTag L cells express numerous fatty acid transport proteins and take up OA in a saturable manner. Oral administration of OA increased the ileal chyme content of OA by 140-fold over 60-120 min (P < 0.05-0.01), peaking at 105 ± 50 μmol/g. To evaluate the direct effects of OA on GLP-1 secretion, 125 mm OA was rectally infused into the colon and terminal ileum of rats. Plasma bioactive GLP-1 increased from 20 ± 6 to 102 ± 21 pg/ml at 60 min (P < 0.01). However, pretreatment with ileocolonic adenoviral PKCζ small interfering RNA resulted in a 68 ± 8% reduction in the GLP-1 response to rectal OA (P < 0.001). The results of these studies indicate that OA levels in the rat terminal gut after oral ingestion are sufficient to induce GLP-1 secretion and that PKCζ is necessary for the effects of OA on GLP-1 secretion in vivo. PKCζ may therefore serve as a novel therapeutic target to enhance GLP-1 levels in patients with type 2 diabetes.
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Affiliation(s)
- Roman Iakoubov
- Department of Physiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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18
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Vrang N, Larsen PJ. Preproglucagon derived peptides GLP-1, GLP-2 and oxyntomodulin in the CNS: role of peripherally secreted and centrally produced peptides. Prog Neurobiol 2010; 92:442-62. [PMID: 20638440 DOI: 10.1016/j.pneurobio.2010.07.003] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2010] [Revised: 07/01/2010] [Accepted: 07/10/2010] [Indexed: 12/16/2022]
Abstract
The scientific understanding of preproglucagon derived peptides has provided people with type 2 diabetes with two novel classes of glucose lowering agents, the dipeptidyl peptidase IV (DPP-IV) inhibitors and GLP-1 receptor agonists. For the scientists, the novel GLP-1 agonists, and DPP-IV inhibitors have evolved as useful tools to understand the role of the preproglucagon derived peptides in normal physiology and disease. However, the overwhelming interest attracted by GLP-1 analogues as potent incretins has somewhat clouded the efforts to understand the importance of preproglucagon derived peptides in other physiological contexts. In particular, our neurobiological understanding of the preproglucagon expressing neuronal pathways in the central nervous system as well as the degree to which central GLP-1 receptors are targeted by peripherally administered GLP-1 receptor agonists is still fairly limited. The role of GLP-1 as an anorectic neurotransmitter is well recognized, but clarification of the neuronal targets and physiological basis of this response is further warranted, as is the mapping of GLP-1 sensitive neurons involved in a variety of neuroendocrine and behavioral responses. Further recent evidence points to GLP-1 as a central neuropeptide with neuroprotective capabilities potentially mitigating a wide array of neurodegenerative conditions. It is the aim of the present review to summarize our current understanding of preproglucagon derived peptides as neurotransmitters in the central nervous system.
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Affiliation(s)
- Niels Vrang
- Gubra ApS, Ridebanevej 12, 1870 Frederiksberg, Denmark.
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19
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Musson MC, Jepeal LI, Sharifnia T, Wolfe MM. Evolutionary conservation of glucose-dependent insulinotropic polypeptide (GIP) gene regulation and the enteroinsular axis. ACTA ACUST UNITED AC 2010; 164:97-104. [PMID: 20621665 DOI: 10.1016/j.regpep.2010.05.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Revised: 05/01/2010] [Accepted: 05/25/2010] [Indexed: 10/19/2022]
Abstract
Glucose-dependent insulinotropic polypeptide (GIP), an important component of the enteroinsular axis, is a potent stimulator of insulin secretion, functioning to maintain nutrient efficiency. Although well-characterized in mammals, little is known regarding GIP transcriptional regulation in Danio rerio (Dr). We previously demonstrated that DrGIP is expressed in the intestine and the pancreas, and we therefore cloned the Dr promoter to compare GIP transcriptional regulation in Dr and mammals. Although no significant homology was indentified between the highly conserved mammalian promoter and the DrGIP promoter, 1072-bp of the DrGIP promoter conferred tissue-specific expression in mammalian cell lines. Deletional analysis of the DrGIP promoter identified two regions that, when deleted, reduced transcription by 75% and 95%, respectively. Mutational analysis of the upstream region suggested involvement of an Nkx binding site, although we were unable to identify the factor binding to this site. The cis element in the downstream region was found to be a GATA binding site. Lastly, overexpression and shRNA experiments identified PAX4 as a potential repressor of DrGIP expression. These findings provide evidence that despite the identification of species-specific transcriptional regulators and differences in GIP expression patterns between D. rerio and mammals, a moderate degree of regulatory conservation appears to exist.
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Affiliation(s)
- Michelle C Musson
- Section of Gastroenterology, Boston University School of Medicine and Boston Medical Center, Boston, MA 02118, USA
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20
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Ashby RS, Megaw PL, Morgan IG. Changes in the expression of Pax6 RNA transcripts in the retina during periods of altered ocular growth in chickens. Exp Eye Res 2009; 89:392-7. [DOI: 10.1016/j.exer.2009.04.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2008] [Revised: 03/22/2009] [Accepted: 04/11/2009] [Indexed: 12/01/2022]
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21
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Nitta Y, Shigeyoshi Y, Nakagata N, Kaneko T, Nitta K, Harada T, Ishizaki F, Townsend J. Kinetics of blood glucose in mice carrying hemizygous Pax6. Exp Anim 2009; 58:105-12. [PMID: 19448333 DOI: 10.1538/expanim.58.105] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
The genotype-phenotype relationship was examined experimentally for the Pax6(Sey-4H) mutant, which carries deletion of its chromosome 2 middle region hemizygously. The genotyping has indicated that this deleted segment is between 102.6 and 109.2 Mb from the centromere. The glucose-6-phosphatase gene followed by the glucagon and carboxyl ester lipase genes were mapped adjacent to the deleted region. Phenotyping indicates that the Pax6(Sey-4H) mutant is more susceptible to diabetes. The glucose tolerance test showed that the mutants were less capable of reducing their level of blood glucose to the standard level than the normal sibs. The insulin-loading test revealed their inability to elevate their blood glucose levels up to normal levels. The time it took for the onset of diabetes induced by streptozotocin was shorter in the mutants than in normal sibs. Both the haploinsufficiency of the genes in the hemizygous segment of chromosome 2 and the quantitative imbalance of the whole genome could contribute the development of this phenotype in the mutant.
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Affiliation(s)
- Yumiko Nitta
- Department of Anatomy and Neuroscience, Faculty of Medicine, Kinki University, Osaka-Sayama, Japan
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22
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Zhu S, Xia HHX, Yang Y, Ma J, Chen M, Hu P, Gu Q, Liang Y, Lin H, Wong BCY. Alterations of gastric homeoprotein expression in Helicobacter pylori infection, incisural antralisation, and intestinal metaplasia. Dig Dis Sci 2009; 54:996-1002. [PMID: 18754095 DOI: 10.1007/s10620-008-0459-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2008] [Accepted: 07/16/2008] [Indexed: 02/07/2023]
Abstract
PURPOSE This study was to determine whether gastric expression of homeoproteins is altered in Helicobacter pylori infection, incisural antralisation, and intestinal metaplasia (IM). METHODS Gastric biopsy specimens were taken from 98 patients with non-ulcer dyspepsia for the detection of H. pylori infection; histological examinations; immunohistochemical staining of CDX2, PDX1, PAX6, and NKX6.1. RESULTS Of the patients, 38 were positive for H. pylori infection, 44 had antral-type mucosa at the incisura, and 22 had IM in the stomach. At the incisura, the expression of PDX1, NKX6.1, and PAX6 in cytoplasm compartment was down-regulated in antral-type mucosa compared with that in the transitional- or body-type mucosa (all P<0.01). The expression of PDX1, PAX6, and NKX6.1 in cytoplasm at the incisura was down-regulated in H. pylori-infected patients compared with that in those without H. pylori infection (all P<0.01). CDX2 expression in whole stomach was up-regulated, but PDX1 expression at the incisura was down-regulated in patients with IM compared with that in those without IM (all P<0.01). CONCLUSIONS Gastric expression of PDX1, PAX 6, and NKX6.1 is down-regulated in H. pylori infection and incisural antralisation. CDX2 is up-regulated but PDX1 is down-regulated in the presence of IM.
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Affiliation(s)
- Senlin Zhu
- Department of Gastroenterology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
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Abstract
The glucagon gene is expressed not only in the alpha cells of the pancreatic islets but also in the endocrine cells of the intestinal epithelium (so-called L-cells), and in certain neurons of the brain stem. Whereas in the pancreas, glucagon, the hyperglycaemic hormone, is cleaved out of the 160 amino acid precursor, proglucagon, leaving behind proglucagon fragments (PG 1-30 and PG 72-158, the so-called major proglucagon fragment (MPGF)) that are probably inactive, the intestinal processing leads to the formation of glicentin (PG 1-69; action uncertain) and glucagon-like peptides 1 (PG 78-107amide, a potent incretin homone, regulating insulin secretion, glucagon secretion, gastrointestinal motility and appetite) and 2 (PG 126-158, a regulator of gut mucosal growth and integrity). The two prohormone convertases PC2 and PC1/3, respectively, are responsible for the differential processing. After their release, the hormones are eliminated mainly in the kidneys, but both GLP-2 and in particular GLP-1, but not glucagon, are metabolized both locally and in the circulation and liver by dipeptidyl peptidase 4 (DPP-4) which inactivates the peptides, suggesting that GLP-1 acts locally rather than in an endocrine manner. A number of transcription factors have been identified that can at least partly explain the differential cellular expression of the glucagon gene as well as the differential tissue-specific processing of the precursor.
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Affiliation(s)
- Jens Juul Holst
- Department of Biomedical Sciences, The Panum Institute, University of Copenhagen, 2200, Copenhagen, Denmark.
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24
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Kim W, Egan JM. The role of incretins in glucose homeostasis and diabetes treatment. Pharmacol Rev 2008; 60:470-512. [PMID: 19074620 DOI: 10.1124/pr.108.000604] [Citation(s) in RCA: 573] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Incretins are gut hormones that are secreted from enteroendocrine cells into the blood within minutes after eating. One of their many physiological roles is to regulate the amount of insulin that is secreted after eating. In this manner, as well as others to be described in this review, their final common raison d'être is to aid in disposal of the products of digestion. There are two incretins, known as glucose-dependent insulinotropic peptide (GIP) and glucagon-like peptide-1 (GLP-1), that share many common actions in the pancreas but have distinct actions outside of the pancreas. Both incretins are rapidly deactivated by an enzyme called dipeptidyl peptidase 4 (DPP4). A lack of secretion of incretins or an increase in their clearance are not pathogenic factors in diabetes. However, in type 2 diabetes (T2DM), GIP no longer modulates glucose-dependent insulin secretion, even at supraphysiological (pharmacological) plasma levels, and therefore GIP incompetence is detrimental to beta-cell function, especially after eating. GLP-1, on the other hand, is still insulinotropic in T2DM, and this has led to the development of compounds that activate the GLP-1 receptor with a view to improving insulin secretion. Since 2005, two new classes of drugs based on incretin action have been approved for lowering blood glucose levels in T2DM: an incretin mimetic (exenatide, which is a potent long-acting agonist of the GLP-1 receptor) and an incretin enhancer (sitagliptin, which is a DPP4 inhibitor). Exenatide is injected subcutaneously twice daily and its use leads to lower blood glucose and higher insulin levels, especially in the fed state. There is glucose-dependency to its insulin secretory capacity, making it unlikely to cause low blood sugars (hypoglycemia). DPP4 inhibitors are orally active and they increase endogenous blood levels of active incretins, thus leading to prolonged incretin action. The elevated levels of GLP-1 are thought to be the mechanism underlying their blood glucose-lowering effects.
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Affiliation(s)
- Wook Kim
- National Institute on Aging, National Institutes of Health, 5600 Nathan Shock Drive, Baltimore, MD 21224, USA
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Fujita Y, Chui JWY, King DS, Zhang T, Seufert J, Pownall S, Cheung AT, Kieffer TJ. Pax6 and Pdx1 are required for production of glucose-dependent insulinotropic polypeptide in proglucagon-expressing L cells. Am J Physiol Endocrinol Metab 2008; 295:E648-57. [PMID: 18593849 DOI: 10.1152/ajpendo.90440.2008] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) are incretin hormones that play important roles in maintaining glucose homeostasis and are being actively pursued as novel therapeutic agents for diabetes. GIP is produced by dispersed enteroendocrine cells and interestingly at times is coexpressed with GLP-1. We sought to determine the factors that selectively define GIP- vs. GLP-1-expressing cells. We performed comparative immunostaining of Pax6 and Pdx1 in GIP- and GLP-1-secreting cells. We investigated whether Pax6 and Pdx1 activate the human GIP promoter in control IEC-6 cells and GIP-expressing STC-1 cells. EMSA was performed to assess the binding of these transcription factors to the GIP promoter. Pax6 and Pdx1 consistently colocalized in GIP-immunoreactive cells. Cells that coexpress GIP and GLP-1 were Pax6 and Pdx1 positive, whereas cells expressing only GLP-1 were Pax6 positive but did not express Pdx1. GIP promoter activity was enhanced in IEC-6 cells by exogenous Pax6 or Pdx1 and diminished in STC-1 cells by inhibition of endogenous Pax6 or Pdx1 by dominant-negative forms. Promoter truncation analysis revealed a major loss of promoter activity when the sequence between -184 to -145 bp was deleted. EMSA studies indicated that Pax6 and Pdx1 bind to this proximal sequence of the human GIP promoter. Our findings indicate that concomitant expression of Pax6 and Pdx1 is important for GIP expression. Our results also suggest that the presence of Pdx1 defines whether GLP-1-expressing gastrointestinal L cells also coexpress GIP.
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Affiliation(s)
- Yukihiro Fujita
- Department of Cellular and Physiological Sciences, Univ. of British Columbia, Vancouver, BC, Canada V6T 1Z3
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Abstract
Glucagon-like peptide 1 (GLP-1) is a 30-amino acid peptide hormone produced in the intestinal epithelial endocrine L-cells by differential processing of proglucagon, the gene which is expressed in these cells. The current knowledge regarding regulation of proglucagon gene expression in the gut and in the brain and mechanisms responsible for the posttranslational processing are reviewed. GLP-1 is released in response to meal intake, and the stimuli and molecular mechanisms involved are discussed. GLP-1 is extremely rapidly metabolized and inactivated by the enzyme dipeptidyl peptidase IV even before the hormone has left the gut, raising the possibility that the actions of GLP-1 are transmitted via sensory neurons in the intestine and the liver expressing the GLP-1 receptor. Because of this, it is important to distinguish between measurements of the intact hormone (responsible for endocrine actions) or the sum of the intact hormone and its metabolites, reflecting the total L-cell secretion and therefore also the possible neural actions. The main actions of GLP-1 are to stimulate insulin secretion (i.e., to act as an incretin hormone) and to inhibit glucagon secretion, thereby contributing to limit postprandial glucose excursions. It also inhibits gastrointestinal motility and secretion and thus acts as an enterogastrone and part of the "ileal brake" mechanism. GLP-1 also appears to be a physiological regulator of appetite and food intake. Because of these actions, GLP-1 or GLP-1 receptor agonists are currently being evaluated for the therapy of type 2 diabetes. Decreased secretion of GLP-1 may contribute to the development of obesity, and exaggerated secretion may be responsible for postprandial reactive hypoglycemia.
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Affiliation(s)
- Jens Juul Holst
- Department of Medical Physiology, The Panum Institute, University of Copenhagen, Copenhagen, Denmark.
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Abstract
This review focuses on the mechanisms regulating the synthesis, secretion, biological actions, and therapeutic relevance of the incretin peptides glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1). The published literature was reviewed, with emphasis on recent advances in our understanding of the biology of GIP and GLP-1. GIP and GLP-1 are both secreted within minutes of nutrient ingestion and facilitate the rapid disposal of ingested nutrients. Both peptides share common actions on islet beta-cells acting through structurally distinct yet related receptors. Incretin-receptor activation leads to glucose-dependent insulin secretion, induction of beta-cell proliferation, and enhanced resistance to apoptosis. GIP also promotes energy storage via direct actions on adipose tissue, and enhances bone formation via stimulation of osteoblast proliferation and inhibition of apoptosis. In contrast, GLP-1 exerts glucoregulatory actions via slowing of gastric emptying and glucose-dependent inhibition of glucagon secretion. GLP-1 also promotes satiety and sustained GLP-1-receptor activation is associated with weight loss in both preclinical and clinical studies. The rapid degradation of both GIP and GLP-1 by the enzyme dipeptidyl peptidase-4 has led to the development of degradation-resistant GLP-1-receptor agonists and dipeptidyl peptidase-4 inhibitors for the treatment of type 2 diabetes. These agents decrease hemoglobin A1c (HbA1c) safely without weight gain in subjects with type 2 diabetes. GLP-1 and GIP integrate nutrient-derived signals to control food intake, energy absorption, and assimilation. Recently approved therapeutic agents based on potentiation of incretin action provide new physiologically based approaches for the treatment of type 2 diabetes.
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Affiliation(s)
- Laurie L Baggio
- Department of Medicine, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
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Gromada J, Franklin I, Wollheim CB. Alpha-cells of the endocrine pancreas: 35 years of research but the enigma remains. Endocr Rev 2007; 28:84-116. [PMID: 17261637 DOI: 10.1210/er.2006-0007] [Citation(s) in RCA: 424] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Glucagon, a hormone secreted from the alpha-cells of the endocrine pancreas, is critical for blood glucose homeostasis. It is the major counterpart to insulin and is released during hypoglycemia to induce hepatic glucose output. The control of glucagon secretion is multifactorial and involves direct effects of nutrients on alpha-cell stimulus-secretion coupling as well as paracrine regulation by insulin and zinc and other factors secreted from neighboring beta- and delta-cells within the islet of Langerhans. Glucagon secretion is also regulated by circulating hormones and the autonomic nervous system. In this review, we describe the components of the alpha-cell stimulus secretion coupling and how nutrient metabolism in the alpha-cell leads to changes in glucagon secretion. The islet cell composition and organization are described in different species and serve as a basis for understanding how the numerous paracrine, hormonal, and nervous signals fine-tune glucagon secretion under different physiological conditions. We also highlight the pathophysiology of the alpha-cell and how hyperglucagonemia represents an important component of the metabolic abnormalities associated with diabetes mellitus. Therapeutic inhibition of glucagon action in patients with type 2 diabetes remains an exciting prospect.
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Affiliation(s)
- Jesper Gromada
- Novartis Institutes for BioMedical Research, 100 Technology Square, Cambridge, Massachusetts 02139, USA.
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Flock G, Cao X, Drucker DJ. Pdx-1 is not sufficient for repression of proglucagon gene transcription in islet or enteroendocrine cells. Endocrinology 2005; 146:441-9. [PMID: 15471960 DOI: 10.1210/en.2004-0495] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Pdx-1 plays a key role in the development of the pancreas and the control of islet gene transcription and has also been proposed as a dominant regulator of the alpha- vs. beta-cell phenotype via extinction of proglucagon expression. To ascertain the relationship between Pdx-1 and proglucagon gene expression, we examined the effect of enhanced pdx-1 expression on proglucagon gene expression in murine islet alphaTC-1 and GLUTag enteroendocrine cells. Although adenoviral transduction increased the levels of pdx-1 mRNA transcripts and nuclear Pdx-1 protein, overexpression of pdx-1 did not repress endogenous proglucagon gene expression in alphaTC-1 or GLUTag cells or murine islets. Immunohistochemical analysis of cells transduced with Ad-pdx-1 demonstrated multiple individual islet or enteroendocrine cells exhibiting both nuclear Pdx-1 and cytoplasmic glucagon-like peptide-1 immunopositivity. The failure of pdx-1 to inhibit endogenous proglucagon gene expression was not attributable to defects in Pdx-1 nuclear translocation or DNA binding as demonstrated using Western blotting and EMSA analyses. Furthermore, Ad-pdx-1 transduction did not repress proglucagon promoter activity in alphaTC-1 or GLUTag cells. Taken together, these findings demonstrate that pdx-1 alone is not sufficient for specification of the hormonal phenotype or extinction of proglucagon gene expression in islet or enteroendocrine cells.
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Affiliation(s)
- Grace Flock
- Department of Medicine, Toronto General Hospital, Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
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Yu S, Zheng L, Trinh DK, Asa SL, Ezzat S. Distinct transcriptional control and action of fibroblast growth factor receptor 4 in differentiating skeletal muscle cells. J Transl Med 2004; 84:1571-80. [PMID: 15467729 DOI: 10.1038/labinvest.3700187] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Although FGF signaling promotes myoblast proliferation and represses myogenic differentiation, one of the FGF receptors (FGFR), FGFR4, is expressed mainly in mature skeletal muscle. Disruption of FGFR4 signaling interrupts chick limb muscle formation. To determine the developmental regulation of FGFR4 expression, we compared the transcriptional control and action of FGFR4 in myoblasts and myotubes. We identified higher FGFR4 expression in differentiated myotubes than precursor myoblasts. FGFR4 promoter activity was localized within a region 115 bp upstream of the transcription start site. Overlapping fragments of this promoter displayed a distinct difference when compared by electromobility shift assay (EMSA) using nuclear extracts from myoblasts and myotubes. While fragments B (-95/-56) and C (-65/-26) formed specific complexes in both cell types, these complexes were consistently more intense in myotubes than myoblasts. These complexes were efficiently competed by an Sp-type oligonucleotide and were supershifted by Sp1 and by Sp3 antibodies. Deletions of the Sp-binding sites in fragment B (-95/-56) confirmed their critical contribution to promoter activity. Moreover, Sp1 expression correlated with FGFR4-expression in myotubes. To determine whether FGFR4 expression regulates myoblast differentiation, we infected a soluble dominant-negative FGFR4-containing adenovirus into these cells. This significantly impeded Erk1/2 phosphorylation and differentiation of myoblasts into MHC-expressing myotubes. Our findings point to distinct transcriptional regulation and action for FGFR4 in differentiating skeletal muscle cells.
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Affiliation(s)
- Shunjiang Yu
- Department of Medicine, Mount Sinai Hospital and University of Toronto, The Freeman Centre for Endocrine Oncology and The Ontario Cancer Institute, Toronto, Ontario, Canada
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Hashimoto T, Nakamura T, Maegawa H, Nishio Y, Egawa K, Kashiwagi A. Regulation of ATP-sensitive potassium channel subunit Kir6.2 expression in rat intestinal insulin-producing progenitor cells. J Biol Chem 2004; 280:1893-900. [PMID: 15528203 DOI: 10.1074/jbc.m410759200] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have reported that the combined expression of Pdx-1 (pancreatic duodenal homeobox 1) and Isl-1 (islet 1) enables immature rat enterocytes (IEC-6) to produce and release insulin. A key component regulating the release of insulin is the ATP-sensitive potassium channel subunit Kir6.2. To investigate the regulation of Kir6.2 gene expression, we assessed Kir6.2 expression in IEC-6 cells expressing Pdx-1 and/or Isl-1. We observed that Kir6.2 protein was expressed de novo in IEC-6 cells expressing both Pdx-1 and Isl-1 but not in cells expressing Pdx-1 alone. Next, we analyzed the regions of the Kir6.2 promoter (-1677/-45) by performing a luciferase assay and electrophoretic mobility shift assay. The results have demonstrated that Kir6.2 promoter possesses two regions regulating the promoter activity: a Foxa2-binding site (-1364 to -1210) and an Sp1/Sp3-binding site (-1035 to -939). The additional expression of Isl-1 in IEC-6 cells expressing Pdx-1 attenuated overexpression of Foxa2 protein and enhanced Kir6.2 expression. Finally, knockdown of Isl-1 using the iRNA technique resulted in decreased expression of Kir6.2 protein in a rat pancreatic beta-cell line (RIN-5F cells). These results indicate that expression of Kir6.2 in the rat intestine is moderated by Isl-1.
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Affiliation(s)
- Tetsuya Hashimoto
- Division of Endocrinology and Metabolism, Department of Medicine, Shiga University of Medical Science, Otsu, Japan
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Yi F, Brubaker PL, Jin T. TCF-4 mediates cell type-specific regulation of proglucagon gene expression by beta-catenin and glycogen synthase kinase-3beta. J Biol Chem 2004; 280:1457-64. [PMID: 15525634 DOI: 10.1074/jbc.m411487200] [Citation(s) in RCA: 297] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The proglucagon gene (glu) encodes glucagon, expressed in pancreatic islets, and the insulinotropic hormone GLP-1, expressed in the intestines. These two hormones exert critical and opposite effects on blood glucose homeostasis. An intriguing question that remains to be answered is whether and how glu gene expression is regulated in a cell type-specific manner. We reported previously that the glu gene promoter in gut endocrine cell lines was stimulated by beta-catenin, the major effector of the Wnt signaling pathway, whereas glu mRNA expression and GLP-1 synthesis were activated via inhibition of glycogen synthase kinase-3beta, the major negative modulator of the Wnt pathway (Ni, Z., Anini, Y., Fang, X., Mills, G. B., Brubaker, P. L., & Jin, T. (2003) J. Biol. Chem. 278, 1380-1387). We now show that beta-catenin and the glycogen synthase kinase-3beta inhibitor lithium do not activate glu mRNA or glu promoter expression in pancreatic cell lines. In the intestinal GLUTag cell line, but not in the pancreatic InR1-G9 cell line, the glu promoter G2 enhancer-element was activated by lithium treatment via a TCF-binding motif. TCF-4 is abundantly expressed in the gut but not in pancreatic islets. Furthermore, both TCF-4 and beta-catenin bind to the glu gene promoter, as detected by chromatin immunoprecipitation. Finally, stable introduction of dominant-negative TCF-4 into the GLUTag cell line repressed basal glu mRNA expression and abolished the effect of lithium on glu mRNA expression and GLP-1 synthesis. We have therefore identified a unique mechanism that regulates glu expression in gut endocrine cells only. Tissue-specific expression of TCF factors thus may play a role in the diversity of the Wnt pathway.
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Affiliation(s)
- Fenghua Yi
- Division of Cell & Molecular Biology, Toronto General Research Institute, University Health Network, University of Toronto, Toronto, Ontario, M5G 2M1, Canada
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Abstract
For over 30 yr, it has been known that enteroendocrine cells derive from common precursor cells in the intestinal crypts. Until recently, relatively little was understood about the events that result in commitment to endocrine differentiation or the segregation of over 10 different hormone-expressing cell types in the gastrointestinal tract. The earliest cell fate decisions appear to be regulated by the Notch signaling pathway. Notch is inactive in endocrine precursor cells, allowing for expression of the proendocrine basic helix-loop-helix proteins Math1 and neurogenin3. Differentiating precursor cells activate Notch in neighboring cells to switch off expression of proendocrine factors and inhibit endocrine differentiation. Math1 is the first factor involved in endocrine specification, committing cells to become one of three secretory lineages-goblet, Paneth, and enteroendocrine. Neurogenin3 appears to be a downstream target that is essential for endocrine cell differentiation. Events that control the segregation of each mature lineage from progenitor cells have not been characterized in detail. The transcription factors Pax4, Pax6, BETA2/NeuroD, and pancreatic-duodenal homeobox 1 have all been implicated in enteroendocrine differentiation. BETA2/NeuroD appears to coordinate secretin gene expression in S-type enteroendocrine cells with cell cycle arrest as cells terminally differentiate. Powerful genetic approaches have established the murine intestine as the most important model for studying enteroendocrine differentiation. Enteroendocrine cells in the mouse are remarkably similar to those in humans, making it likely that insights learned from the mouse may contribute to both our understanding and treatment of a variety of human disorders.
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Affiliation(s)
- Susan E Schonhoff
- Division of Gastroenterology No. 218, New England Medical Center, 750 Washington Street, Boston, Massachusetts 02111, USA
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Walters JRF. Cell and molecular biology of the small intestine: new insights into differentiation, growth and repair. Curr Opin Gastroenterol 2004; 20:70-6. [PMID: 15703624 DOI: 10.1097/00001574-200403000-00004] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
PURPOSE OF REVIEW This paper will discuss recent research that has provided new insights into the molecular and cell biology of the small intestine. RECENT FINDINGS Differentiation of the epithelial cell lineages, including the enterocytes, enteroendocrine, Goblet and Paneth cells, from the stem cells is better understood. Important interactions have been demonstrated between these cells, luminal bacteria, and underlying mesenchymal tissue. Intestine-specific gene expression is regulated by transcription factors that are becoming well characterized, including CDX1, CDX2 and HNF1. The actions of growth factors such as GLP-2 and EGF are now known to be complex, demonstrating multiple effects in this tissue at a number of levels. SUMMARY Progress in the cellular and molecular biology of the small intestine is producing many intriguing new findings.
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Affiliation(s)
- Julian R F Walters
- Gastroenterology Section, Department of Medicine, Faculty of Medicine, Imperial College London, Hammersmith Hospital, London, UK.
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Current literature in diabetes. Diabetes Metab Res Rev 2003; 19:248-55. [PMID: 12789659 DOI: 10.1002/dmrr.348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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