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Gonzales N, Garrity C, Rivas I, McEligot H, Vapniarsky N. Auricular Chondrocytes as a Cell Source for Scaffold-Free Elastic Cartilage Tissue Engineering. Tissue Eng Part C Methods 2024; 30:314-322. [PMID: 38946581 DOI: 10.1089/ten.tec.2024.0106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/02/2024] Open
Abstract
Current tissue engineering (TE) methods utilize chondrocytes primarily from costal or articular sources. Despite the robust mechanical properties of neocartilages sourced from these cells, the lack of elasticity and invasiveness of cell collection from these sources negatively impact clinical translation. These limitations invited the exploration of naturally elastic auricular cartilage as an alternative cell source. This study aimed to determine if auricular chondrocytes (AuCs) can be used for TE scaffold-free neocartilage constructs and assess their biomechanical properties. Neocartilages were successfully generated from a small quantity of primary neonatal AuCs of three minipig donors (n = 3). Neocartilage constructs had instantaneous moduli of 200.5 kPa ± 43.34 and 471.9 ± 92.8 kPa at 10% and 20% strain, respectively. TE constructs' relaxation moduli (Er) were 36.99 ± 6.47 kPa Er and 110.3 ± 16.99 kPa at 10% and 20% strain, respectively. The Young's modulus was 2.0 MPa ± 0.63, and the ultimate tensile strength was 0.619 ± 0.177 MPa. AuC-derived neocartilages contained 0.144 ± 0.011 µg collagen, 0.185 µg ± 0.002 glycosaminoglycans per µg dry weight, and 1.7e-3 µg elastin per µg dry weight. In conclusion, this study shows that AuCs can be used as a reliable and easily accessible cell source for TE of biomimetic and mechanically robust elastic neocartilage implants.
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Affiliation(s)
- Nicole Gonzales
- Department of Pathology, Microbiology, and Immunology, University of California, Davis, California, USA
| | - Carissa Garrity
- Department of Pathology, Microbiology, and Immunology, University of California, Davis, California, USA
| | - Iris Rivas
- Department of Pathology, Microbiology, and Immunology, University of California, Davis, California, USA
| | - Heather McEligot
- Department of Pathology, Microbiology, and Immunology, University of California, Davis, California, USA
| | - Natalia Vapniarsky
- Department of Pathology, Microbiology, and Immunology, University of California, Davis, California, USA
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2
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Maejima Y, Yokota S, Hidema S, Nishimori K, de Wet H, Shimomura K. Systemic Co-Administration of Low-Dose Oxytocin and Glucagon-Like Peptide 1 Additively Decreases Food Intake and Body Weight. Neuroendocrinology 2024; 114:639-657. [PMID: 38599201 DOI: 10.1159/000538792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Accepted: 04/08/2024] [Indexed: 04/12/2024]
Abstract
INTRODUCTION GLP-1 receptor agonists are the number one drug prescribed for the treatment of obesity and type 2 diabetes. These drugs are not, however, without side effects, and in an effort to maximize therapeutic effect while minimizing adverse effects, gut hormone co-agonists received considerable attention as new drug targets in the fight against obesity. Numerous previous reports identified the neuropeptide oxytocin (OXT) as a promising anti-obesity drug. The aims of this study were to evaluate OXT as a possible co-agonist for GLP-1 and examine the effects of its co-administration on food intake (FI) and body weight (BW) in mice. METHODS FI and c-Fos levels were measured in the feeding centers of the brain in response to an intraperitoneal injection of saline, OXT, GLP-1, or OXT/GLP-1. The action potential frequency and cytosolic Ca2+ ([Ca2+]i) in response to OXT, GLP-1, or OXT/GLP-1 were measured in ex vivo paraventricular nucleus (PVN) neuronal cultures. Finally, FI and BW changes were compared in diet-induced obese mice treated with saline, OXT, GLP-1, or OXT/GLP-1 for 13 days. RESULTS Single injection of OXT/GLP-1 additively decreased FI and increased c-Fos expression specifically in the PVN and supraoptic nucleus. Seventy percent of GLP-1 receptor-positive neurons in the PVN also expressed OXT receptors, and OXT/GLP-1 co-administration dramatically increased firing and [Ca2+]i in the PVN OXT neurons. The chronic OXT/GLP-1 co-administration decreased BW without changing FI. CONCLUSION Chronic OXT/GLP-1 co-administration decreases BW, possibly via the activation of PVN OXT neurons. OXT might be a promising candidate as an incretin co-agonist in obesity treatment.
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Affiliation(s)
- Yuko Maejima
- Department of Bioregulation and Pharmacological Medicine, Fukushima Medical University School of Medicine, Fukushima, Japan
- Departments of Obesity and Inflammation Research, Fukushima Medical University School of Medicine, Fukushima, Japan
- Department of Physiology, Anatomy and Genetics, Sherrington Building, University of Oxford, Oxford, UK
| | - Shoko Yokota
- Department of Bioregulation and Pharmacological Medicine, Fukushima Medical University School of Medicine, Fukushima, Japan
| | - Shizu Hidema
- Department of Bioregulation and Pharmacological Medicine, Fukushima Medical University School of Medicine, Fukushima, Japan
| | - Katsuhiko Nishimori
- Departments of Obesity and Inflammation Research, Fukushima Medical University School of Medicine, Fukushima, Japan
| | - Heidi de Wet
- Department of Physiology, Anatomy and Genetics, Sherrington Building, University of Oxford, Oxford, UK
| | - Kenju Shimomura
- Department of Bioregulation and Pharmacological Medicine, Fukushima Medical University School of Medicine, Fukushima, Japan
- Departments of Obesity and Inflammation Research, Fukushima Medical University School of Medicine, Fukushima, Japan
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3
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Jakubowska A, le Roux CW, Viljoen A. The Road towards Triple Agonists: Glucagon-Like Peptide 1, Glucose-Dependent Insulinotropic Polypeptide and Glucagon Receptor - An Update. Endocrinol Metab (Seoul) 2024; 39:12-22. [PMID: 38356208 PMCID: PMC10901658 DOI: 10.3803/enm.2024.1942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Revised: 01/29/2024] [Accepted: 01/31/2024] [Indexed: 02/16/2024] Open
Abstract
Obesity is the fifth leading risk factor for global deaths with numbers continuing to increase worldwide. In the last 20 years, the emergence of pharmacological treatments for obesity based on gastrointestinal hormones has transformed the therapeutic landscape. The successful development of glucagon-like peptide-1 (GLP-1) receptor agonists, followed by the synergistic combined effect of glucose-dependent insulinotropic polypeptide (GIP)/GLP-1 receptor agonists achieved remarkable weight loss and glycemic control in those with the diseases of obesity and type 2 diabetes. The multiple cardiometabolic benefits include improving glycemic control, lipid profiles, blood pressure, inflammation, and hepatic steatosis. The 2023 phase 2 double-blind, randomized controlled trial evaluating a GLP-1/GIP/glucagon receptor triagonist (retatrutide) in patients with the disease of obesity reported 24.2% weight loss at 48 weeks with 12 mg retatrutide. This review evaluates the current available evidence for GLP-1 receptor agonists, dual GLP-1/GIP receptor co-agonists with a focus on GLP-1/GIP/glucagon receptor triagonists and discusses the potential future benefits and research directions.
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Affiliation(s)
| | - Carel W. le Roux
- Diabetes Complications Research Centre, University College Dublin, Dublin, Ireland
| | - Adie Viljoen
- Borthwick Diabetes Research Centre, Lister Hospital, Stevenage, UK
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4
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Nogueiras R, Nauck MA, Tschöp MH. Gut hormone co-agonists for the treatment of obesity: from bench to bedside. Nat Metab 2023:10.1038/s42255-023-00812-z. [PMID: 37308724 DOI: 10.1038/s42255-023-00812-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 04/24/2023] [Indexed: 06/14/2023]
Abstract
The discovery and development of so-called gut hormone co-agonists as a new class of drugs for the treatment of diabetes and obesity is considered a transformative breakthrough in the field. Combining action profiles of multiple gastrointestinal hormones within a single molecule, these novel therapeutics achieve synergistic metabolic benefits. The first such compound, reported in 2009, was based on balanced co-agonism at glucagon and glucagon-like peptide-1 (GLP-1) receptors. Today, several classes of gut hormone co-agonists are in development and advancing through clinical trials, including dual GLP-1-glucose-dependent insulinotropic polypeptide (GIP) co-agonists (first described in 2013), and triple GIP-GLP-1-glucagon co-agonists (initially designed in 2015). The GLP-1-GIP co-agonist tirzepatide was approved in 2022 by the US Food and Drug Administration for the treatment of type 2 diabetes, providing superior HbA1c reductions compared to basal insulin or selective GLP-1 receptor agonists. Tirzepatide also achieved unprecedented weight loss of up to 22.5%-similar to results achieved with some types of bariatric surgery-in non-diabetic individuals with obesity. In this Perspective, we summarize the discovery, development, mechanisms of action and clinical efficacy of the different types of gut hormone co-agonists, and discuss potential challenges, limitations and future developments.
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Affiliation(s)
- Ruben Nogueiras
- CIMUS, University of Santiago de Compostela, Santiago de Compostela, Spain
- Galicia Agency of Innovation, Xunta de Galicia, Santiago de Compostela, Spain
| | - Michael A Nauck
- Diabetes, Endocrinology and Metabolism Section, Medical Department I, St. Josef-Hospital, Katholisches Klinikum Bochum, Ruhr University of Bochum, Bochum, Germany
| | - Matthias H Tschöp
- Helmholtz Zentrum München, Neuherberg, Germany.
- Division of Metabolic Diseases, Department of Medicine, Technische Universität München, München, Germany.
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5
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Schalla MA, Taché Y, Stengel A. Neuroendocrine Peptides of the Gut and Their Role in the Regulation of Food Intake. Compr Physiol 2021; 11:1679-1730. [PMID: 33792904 DOI: 10.1002/cphy.c200007] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The regulation of food intake encompasses complex interplays between the gut and the brain. Among them, the gastrointestinal tract releases different peptides that communicate the metabolic state to specific nuclei in the hindbrain and the hypothalamus. The present overview gives emphasis on seven peptides that are produced by and secreted from specialized enteroendocrine cells along the gastrointestinal tract in relation with the nutritional status. These established modulators of feeding are ghrelin and nesfatin-1 secreted from gastric X/A-like cells, cholecystokinin (CCK) secreted from duodenal I-cells, glucagon-like peptide 1 (GLP-1), oxyntomodulin, and peptide YY (PYY) secreted from intestinal L-cells and uroguanylin (UGN) released from enterochromaffin (EC) cells. © 2021 American Physiological Society. Compr Physiol 11:1679-1730, 2021.
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Affiliation(s)
- Martha A Schalla
- Charité Center for Internal Medicine and Dermatology, Department for Psychosomatic Medicine, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Berlin, Germany
| | - Yvette Taché
- Vatche and Tamar Manoukian Division of Digestive Diseases, Department of Medicine, CURE: Digestive Diseases Research Center, David Geffen School of Medicine, UCLA, Los Angeles, California, USA.,VA Greater Los Angeles Healthcare System, Los Angeles, California, USA
| | - Andreas Stengel
- Charité Center for Internal Medicine and Dermatology, Department for Psychosomatic Medicine, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Berlin, Germany.,Department of Psychosomatic Medicine and Psychotherapy, Medical University Hospital Tübingen, Tübingen, Germany
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6
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Huang WK, Xie C, Young RL, Zhao JB, Ebendorff-Heidepriem H, Jones KL, Rayner CK, Wu TZ. Development of innovative tools for investigation of nutrient-gut interaction. World J Gastroenterol 2020; 26:3562-3576. [PMID: 32742126 PMCID: PMC7366065 DOI: 10.3748/wjg.v26.i25.3562] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Revised: 05/29/2020] [Accepted: 06/17/2020] [Indexed: 02/06/2023] Open
Abstract
The gastrointestinal tract is the key interface between the ingesta and the human body. There is wide recognition that the gastrointestinal response to nutrients or bioactive compounds, particularly the secretion of numerous hormones, is critical to the regulation of appetite, body weight and blood glucose. This concept has led to an increasing focus on “gut-based” strategies for the management of metabolic disorders, including type 2 diabetes and obesity. Understanding the underlying mechanisms and downstream effects of nutrient-gut interactions is fundamental to effective translation of this knowledge to clinical practice. To this end, an array of research tools and platforms have been developed to better understand the mechanisms of gut hormone secretion from enteroendocrine cells. This review discusses the evolution of in vitro and in vivo models and the integration of innovative techniques that will ultimately enable the development of novel therapies for metabolic diseases.
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Affiliation(s)
- Wei-Kun Huang
- Adelaide Medical School, Centre of Research Excellence in Translating Nutritional Science to Good Health, the University of Adelaide, Adelaide, SA 5005, Australia
- Institute for Photonics and Advanced Sensing, School of Physical Sciences, University of Adelaide, Adelaide, SA 5005, Australia
- The ARC Centre of Excellence for Nanoscale BioPhotonics, Adelaide, SA 5005, Australia
| | - Cong Xie
- Adelaide Medical School, Centre of Research Excellence in Translating Nutritional Science to Good Health, the University of Adelaide, Adelaide, SA 5005, Australia
| | - Richard L Young
- Adelaide Medical School, Centre of Research Excellence in Translating Nutritional Science to Good Health, the University of Adelaide, Adelaide, SA 5005, Australia
- Diabetes, Nutrition and Gut Health, Lifelong Health, South Australia Health and Medical Research Institute, Adelaide, SA 5005, Australia
| | - Jiang-Bo Zhao
- Institute for Photonics and Advanced Sensing, School of Physical Sciences, University of Adelaide, Adelaide, SA 5005, Australia
- The ARC Centre of Excellence for Nanoscale BioPhotonics, Adelaide, SA 5005, Australia
| | - Heike Ebendorff-Heidepriem
- Institute for Photonics and Advanced Sensing, School of Physical Sciences, University of Adelaide, Adelaide, SA 5005, Australia
- The ARC Centre of Excellence for Nanoscale BioPhotonics, Adelaide, SA 5005, Australia
| | - Karen L Jones
- Adelaide Medical School, Centre of Research Excellence in Translating Nutritional Science to Good Health, the University of Adelaide, Adelaide, SA 5005, Australia
| | - Christopher K Rayner
- Adelaide Medical School, Centre of Research Excellence in Translating Nutritional Science to Good Health, the University of Adelaide, Adelaide, SA 5005, Australia
- Department of Gastroenterology and Hepatology, Royal Adelaide Hospital, Adelaide, SA 5000, Australia
| | - Tong-Zhi Wu
- Adelaide Medical School, Centre of Research Excellence in Translating Nutritional Science to Good Health, the University of Adelaide, Adelaide, SA 5005, Australia
- Department of Endocrinology, Zhongda Hospital, Institute of Diabetes, School of Medicine, Southeast University, Nanjing 210009, Jiangsu Province, China
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7
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Davis EM, Sandoval DA. Glucagon‐Like Peptide‐1: Actions and Influence on Pancreatic Hormone Function. Compr Physiol 2020; 10:577-595. [DOI: 10.1002/cphy.c190025] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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8
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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: 875] [Impact Index Per Article: 175.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 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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9
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Vapniarsky N, Huwe LW, Arzi B, Houghton MK, Wong ME, Wilson JW, Hatcher DC, Hu JC, Athanasiou KA. Tissue engineering toward temporomandibular joint disc regeneration. Sci Transl Med 2019; 10:10/446/eaaq1802. [PMID: 29925634 DOI: 10.1126/scitranslmed.aaq1802] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Accepted: 05/25/2018] [Indexed: 12/11/2022]
Abstract
Treatments for temporomandibular joint (TMJ) disc thinning and perforation, conditions prevalent in TMJ pathologies, are palliative but not reparative. To address this, scaffold-free tissue-engineered implants were created using allogeneic, passaged costal chondrocytes. A combination of compressive and bioactive stimulation regimens produced implants with mechanical properties akin to those of the native disc. Efficacy in repairing disc thinning was examined in minipigs. Compared to empty controls, treatment with tissue-engineered implants restored disc integrity by inducing 4.4 times more complete defect closure, formed 3.4-fold stiffer repair tissue, and promoted 3.2-fold stiffer intralaminar fusion. The osteoarthritis score (indicative of degenerative changes) of the untreated group was 3.0-fold of the implant-treated group. This tissue engineering strategy paves the way for developing tissue-engineered implants as clinical treatments for TMJ disc thinning.
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Affiliation(s)
- Natalia Vapniarsky
- Department of Pathology, Microbiology, and Immunology, University of California, Davis, Davis, CA 95616, USA
| | - Le W Huwe
- Department of Biomedical Engineering, University of California, Davis, Davis, CA 95616, USA
| | - Boaz Arzi
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, Davis, CA 95616, USA
| | - Meghan K Houghton
- Directorate for Computer and Information Science and Engineering, National Science Foundation, Alexandria, VA 22314, USA
| | - Mark E Wong
- Department of Oral and Maxillofacial Surgery, University of Texas School of Dentistry, Houston, TX 77054, USA
| | - James W Wilson
- Department of Oral and Maxillofacial Surgery, University of Texas School of Dentistry, Houston, TX 77054, USA
| | - David C Hatcher
- Diagnostic Digital Imaging Center, Sacramento, CA 95825, USA
| | - Jerry C Hu
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA 92697, USA
| | - Kyriacos A Athanasiou
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA 92697, USA.
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10
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Tudurí E, Glavas MM, Asadi A, Baker RK, Ellis CE, Soukhatcheva G, Philit M, Huynh FK, Johnson JD, Bruce Verchere C, Kieffer TJ. AAV GCG-EGFP, a new tool to identify glucagon-secreting α-cells. Sci Rep 2019; 9:10829. [PMID: 31346189 PMCID: PMC6658537 DOI: 10.1038/s41598-019-46735-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 07/04/2019] [Indexed: 01/07/2023] Open
Abstract
The study of primary glucagon-secreting α-cells is hampered by their low abundance and scattered distribution in rodent pancreatic islets. We have designed a double-stranded adeno-associated virus containing a rat proglucagon promoter (700 bp) driving enhanced green fluorescent protein (AAV GCG-EGFP), to specifically identify α-cells. The administration of AAV GCG-EGFP by intraperitoneal or intraductal injection led to EGFP expression selectively in the α-cell population. AAV GCG-EGFP delivery to mice followed by islet isolation, dispersion and separation by FACS for EGFP resulted in an 86% pure population of α-cells. Furthermore, the administration of AAV GCG-EGFP at various doses to adult wild type mice did not significantly alter body weight, blood glucose, plasma insulin or glucagon levels, glucose tolerance or arginine tolerance. In vitro experiments in transgene positive α-cells demonstrated that EGFP expression did not alter the intracellular Ca2+ pattern in response to glucose or adrenaline. This approach may be useful for studying purified primary α-cells and for the in vivo delivery of other genes selectively to α-cells to further probe their function or to manipulate them for therapeutic purposes.
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Affiliation(s)
- Eva Tudurí
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada.,Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Madrid, Spain.,Instituto de Investigación, Desarrollo e innovación en Biotecnología Sanitaria de Elche (IDiBE), Elche, Spain
| | - Maria M Glavas
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Ali Asadi
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Robert K Baker
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Cara E Ellis
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Galina Soukhatcheva
- Department of Pathology and Laboratory Medicine, BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada
| | - Marjolaine Philit
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Frank K Huynh
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada.,Department of Biological Sciences, San Jose State University, San Jose, CA, USA
| | - James D Johnson
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada.,Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada
| | - C Bruce Verchere
- Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada.,Department of Pathology and Laboratory Medicine, BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada
| | - Timothy J Kieffer
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada. .,Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada.
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11
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Drucker DJ. The Discovery of GLP-2 and Development of Teduglutide for Short Bowel Syndrome. ACS Pharmacol Transl Sci 2019; 2:134-142. [PMID: 32219218 DOI: 10.1021/acsptsci.9b00016] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2019] [Indexed: 12/18/2022]
Abstract
The proglucagon gene encodes multiple structurally related peptides with overlapping actions promoting the absorption and assimilation of ingested energy. Notably, glucagon has been developed pharmaceutically to treat hypoglycemia, and glucagon-like peptide-1 (GLP-1) receptor agonists are used for the therapy of type 2 diabetes and obesity. Here I describe the discovery of glucagon-like peptide-2 (GLP-2), a 33 amino acid peptide cosecreted together with GLP-1 from gut endocrine cells. GLP-2 was found to exhibit robust intestinal growth-promoting activity, following serendipitous observations that proglucagon-producing tumors induced intestinal growth in mice. Key developments in the pharmaceutical development of GLP-2 included the cloning of the GLP-2 receptor, and the recognition of the importance of dipeptidyl peptidase-4 as a critical determinant of GLP-2 bioactivity. A therapeutic focus on short bowel syndrome, a serious medical disorder with compelling unmet medical need, enabled the pharmaceutical development of a simple GLP-2 analogue, teduglutide, suitable for once daily administration.
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Affiliation(s)
- Daniel J Drucker
- Department of Medicine, the Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, University of Toronto, Toronto, Ontario M5G 1X5, Canada
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12
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Abstract
Pancreatic alpha cells are generally considered the only source of glucagon secretion in humans. In the 1970s several groups investigating totally pancreatectomised animals reported that glucagon-like immunoreactive material could be detected in the gastrointestinal tract and reopened the question of an extrapancreatic source of glucagon proposed in 1948 when a hyperglycaemic substance was found in the gastrointestinal tract of dogs and rabbits. Nevertheless, over the years, controversy about the existence of extrapancreatic glucagon has flourished as it proved difficult to accurately measure fully processed 29-amino acid glucagon. Recent advances in analytical methods have increased sensitivity and specificity of glucagon assays and, furthermore, technical advances in mass spectrometry-based proteomics have made the detection of low-abundant peptides, such as glucagon, in human plasma more accurate. Here we review new data on extrapancreatic glucagon secretion in the context of historical data and recent analytical breakthroughs. Furthermore, the source, regulation and potential physiological role of extrapancreatic glucagon are discussed and ongoing challenges and knowledge-gaps are outlined.
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Affiliation(s)
- Asger Lund
- Clinical Metabolic Physiology, Steno Diabetes Center Copenhagen, Gentofte Hospital, Hellerup, Denmark; Department of Medicine, Gentofte Hospital, University of Copenhagen, Copenhagen, Denmark.
| | - Filip K Knop
- Clinical Metabolic Physiology, Steno Diabetes Center Copenhagen, Gentofte Hospital, Hellerup, Denmark; Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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13
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Brubaker PL. Glucagon‐like Peptide‐2 and the Regulation of Intestinal Growth and Function. Compr Physiol 2018; 8:1185-1210. [DOI: 10.1002/cphy.c170055] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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14
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Arifin SA, Paternoster S, Carlessi R, Casari I, Ekberg JH, Maffucci T, Newsholme P, Rosenkilde MM, Falasca M. Oleoyl-lysophosphatidylinositol enhances glucagon-like peptide-1 secretion from enteroendocrine L-cells through GPR119. Biochim Biophys Acta Mol Cell Biol Lipids 2018; 1863:1132-1141. [PMID: 29883799 DOI: 10.1016/j.bbalip.2018.06.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 04/24/2018] [Accepted: 06/02/2018] [Indexed: 02/08/2023]
Abstract
The gastrointestinal tract is increasingly viewed as critical in controlling glucose metabolism, because of its role in secreting multiple glucoregulatory hormones, such as glucagon like peptide-1 (GLP-1). Here we investigate the molecular pathways behind the GLP-1- and insulin-secreting capabilities of a novel GPR119 agonist, Oleoyl-lysophosphatidylinositol (Oleoyl-LPI). Oleoyl-LPI is the only LPI species able to potently stimulate the release of GLP-1 in vitro, from murine and human L-cells, and ex-vivo from murine colonic primary cell preparations. Here we show that Oleoyl-LPI mediates GLP-1 secretion through GPR119 as this activity is ablated in cells lacking GPR119 and in colonic primary cell preparation from GPR119-/- mice. Similarly, Oleoyl-LPI-mediated insulin secretion is impaired in islets isolated from GPR119-/- mice. On the other hand, GLP-1 secretion is not impaired in cells lacking GPR55 in vitro or in colonic primary cell preparation from GPR55-/- mice. We therefore conclude that GPR119 is the Oleoyl-LPI receptor, upstream of ERK1/2 and cAMP/PKA/CREB pathways, where primarily ERK1/2 is required for GLP-1 secretion, while CREB activation appears dispensable.
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Affiliation(s)
- Syamsul A Arifin
- Centre for Cell Biology and Cutaneous Research, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, E1 2AT London, United Kingdom; Department of Basic Medical Science for Nursing, Kulliyyah of Nursing, IIUM, Bandar Indera Mahkota, 25200 Kuantan, Pahang, Malaysia
| | - Silvano Paternoster
- Metabolic Signalling Group, School of Pharmacy and Biomedical Sciences, Curtin Health Innovation Research Institute, Curtin University, Perth, Western Australia 6102, Australia
| | - Rodrigo Carlessi
- Cell and Molecular Metabolism Laboratory, School of Pharmacy and Biomedical Sciences, Curtin Health Innovation Research Institute, Curtin University, Perth, Western Australia 6102, Australia
| | - Ilaria Casari
- Metabolic Signalling Group, School of Pharmacy and Biomedical Sciences, Curtin Health Innovation Research Institute, Curtin University, Perth, Western Australia 6102, Australia
| | - Jeppe Hvidtfeldt Ekberg
- Laboratory for Molecular Pharmacology, Department for Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Tania Maffucci
- Centre for Cell Biology and Cutaneous Research, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, E1 2AT London, United Kingdom
| | - Philip Newsholme
- Cell and Molecular Metabolism Laboratory, School of Pharmacy and Biomedical Sciences, Curtin Health Innovation Research Institute, Curtin University, Perth, Western Australia 6102, Australia
| | - Mette M Rosenkilde
- Laboratory for Molecular Pharmacology, Department for Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Marco Falasca
- Centre for Cell Biology and Cutaneous Research, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, E1 2AT London, United Kingdom; Metabolic Signalling Group, School of Pharmacy and Biomedical Sciences, Curtin Health Innovation Research Institute, Curtin University, Perth, Western Australia 6102, Australia.
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15
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Drucker DJ, Habener JF, Holst JJ. Discovery, characterization, and clinical development of the glucagon-like peptides. J Clin Invest 2017; 127:4217-4227. [PMID: 29202475 DOI: 10.1172/jci97233] [Citation(s) in RCA: 235] [Impact Index Per Article: 33.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The discovery, characterization, and clinical development of glucagon-like-peptide-1 (GLP-1) spans more than 30 years and includes contributions from multiple investigators, science recognized by the 2017 Harrington Award Prize for Innovation in Medicine. Herein, we provide perspectives on the historical events and key experimental findings establishing the biology of GLP-1 as an insulin-stimulating glucoregulatory hormone. Important attributes of GLP-1 action and enteroendocrine science are reviewed, with emphasis on mechanistic advances and clinical proof-of-concept studies. The discovery that GLP-2 promotes mucosal growth in the intestine is described, and key findings from both preclinical studies and the GLP-2 clinical development program for short bowel syndrome (SBS) are reviewed. Finally, we summarize recent progress in GLP biology, highlighting emerging concepts and scientific insights with translational relevance.
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Affiliation(s)
- Daniel J Drucker
- Lunenfeld-Tanenbaum Research Institute, Mt. Sinai Hospital, University of Toronto, Toronto, Ontario, Canada
| | - Joel F Habener
- Laboratory of Molecular Endocrinology, Massachusetts General Hospital, Harvard University, Boston, Massachusetts, USA
| | - Jens Juul Holst
- Novo Nordisk Foundation Center for Basic Metabolic Research, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
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16
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Pujadas G, Drucker DJ. Vascular Biology of Glucagon Receptor Superfamily Peptides: Mechanistic and Clinical Relevance. Endocr Rev 2016; 37:554-583. [PMID: 27732058 DOI: 10.1210/er.2016-1078] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Regulatory peptides produced in islet and gut endocrine cells, including glucagon, glucagon-like peptide-1 (GLP-1), GLP-2, and glucose-dependent insulinotropic polypeptide, exert actions with considerable metabolic importance and translational relevance. Although the clinical development of GLP-1 receptor agonists and dipeptidyl peptidase-4 inhibitors has fostered research into how these hormones act on the normal and diseased heart, less is known about the actions of these peptides on blood vessels. Here we review the effects of these peptide hormones on normal blood vessels and highlight their vascular actions in the setting of experimental and clinical vascular injury. The cellular localization and signal transduction properties of the receptors for glucagon, GLP-1, GLP-2, and glucose-dependent insulinotropic polypeptide are discussed, with emphasis on endothelial cells and vascular smooth muscle cells. The actions of these peptides on the control of blood flow, blood pressure, angiogenesis, atherosclerosis, and vascular inflammation are reviewed with a focus on elucidating direct and indirect mechanisms of action. How these peptides traverse the blood-brain barrier is highlighted, with relevance to the use of GLP-1 receptor agonists to treat obesity and neurodegenerative disorders. Wherever possible, we compare actions identified in cell lines and primary cell culture with data from preclinical studies and, when available, results of human investigation, including studies in subjects with diabetes, obesity, and cardiovascular disease. Throughout the review, we discuss pitfalls, limitations, and challenges of the existing literature and highlight areas of controversy and uncertainty. The increasing use of peptide-based therapies for the treatment of diabetes and obesity underscores the importance of understanding the vascular biology of peptide hormone action.
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Affiliation(s)
- Gemma Pujadas
- Department of Medicine, Lunenfeld-Tanenbaum Research Institute, Mt. Sinai Hospital, University of Toronto, Toronto, ON M5G 1X5, Canada
| | - Daniel J Drucker
- Department of Medicine, Lunenfeld-Tanenbaum Research Institute, Mt. Sinai Hospital, University of Toronto, Toronto, ON M5G 1X5, Canada
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17
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Tian L, Jin T. The incretin hormone GLP-1 and mechanisms underlying its secretion. J Diabetes 2016; 8:753-765. [PMID: 27287542 DOI: 10.1111/1753-0407.12439] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 05/09/2016] [Accepted: 06/02/2016] [Indexed: 12/25/2022] Open
Abstract
Glucagon-like peptide-1 (GLP-1) is a cell type-specific post-translational product of proglucagon. It is encoded by the proglucagon gene and released primarily from intestinal endocrine L-cells in response to hormonal, neuronal, and nutritional stimuli. In addition to serving as an incretin in mediating the effect of meal consumption on insulin secretion, GLP-1 exerts other functions in pancreatic islets, including regulation of β-cell proliferation and protection of β-cells against metabolic stresses. Furthermore, GLP-1 exerts numerous other functions in extrapancreatic organs, whereas brain GLP-1 signaling controls satiety. Herein we review the discovery of two incretins and the development of GLP-1-based drugs. We also describe the development of cellular models for studying mechanisms underlying GLP-1 secretion over the past 30 years. However, the main content of this review is a summary of studies on the exploration of mechanisms underlying GLP-1 secretion. We not only summarize studies conducted over the past three decades on elucidating the role of nutritional components and hormonal factors in regulating GLP-1 secretion, but also present a few very recent studies showing the possible role of dietary polyphenols. Finally, the emerging role of gut microbiota in metabolic homeostasis with the potential implication on GLP-1 secretion is discussed.
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Affiliation(s)
- Lili Tian
- Division of Advanced Diagnostics, Toronto General Research Institute, University Health Network, Toronto, Ontario, Canada
- Banting & Best Diabetes Centre, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Tianru Jin
- Division of Advanced Diagnostics, Toronto General Research Institute, University Health Network, Toronto, Ontario, Canada.
- Banting & Best Diabetes Centre, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada.
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18
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Protein digestion and energy homeostasis: How generated peptides may impact intestinal hormones? Food Res Int 2016. [DOI: 10.1016/j.foodres.2015.12.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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19
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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: 2.4] [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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Kihira Y, Burentogtokh A, Itoh M, Izawa-Ishizawa Y, Ishizawa K, Ikeda Y, Tsuchiya K, Tamaki T. Hypoxia decreases glucagon-like peptide-1 secretion from the GLUTag cell line. Biol Pharm Bull 2016; 38:514-21. [PMID: 25832631 DOI: 10.1248/bpb.b14-00612] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Glucagon-like peptide-1 (GLP-1), an incretin hormone, is secreted from L cells located in the intestinal epithelium. It is known that intestinal oxygen tension is decreased postprandially. In addition, we found that the expression of hypoxia-inducible factor-1α (HIF-1α), which accumulates in cells under hypoxic conditions, was significantly increased in the colons of mice with food intake, indicating that the oxygen concentration is likely reduced in the colon after eating. Therefore, we hypothesized that GLP-1 secretion is affected by oxygen tension. We found that forskolin-stimulated GLP-1 secretion from GLUTag cells, a model of intestinal L cells, is suppressed in hypoxia (1% O2). Forskolin-stimulated elevations of preproglucagon (ppGCG) and proprotein convertase 1/3 (PC1/3) mRNA expression were decreased under hypoxic conditions. The finding that H89, a protein kinase A (PKA) inhibitor, inhibited the forskolin-stimulated increase of ppGCG and PC1/3 indicated that the cAMP-PKA pathway is involved in the hypoxia-induced suppression of the genes. Hypoxia decreased hexokinase 2 mRNA and protein expression and increased lactate dehydrogenase A mRNA and protein expression. Concomitantly, lactate production was increased and ATP production was decreased. Together, the results indicate that hypoxia decreases glucose utilization for ATP production, which probably causes a decrease in cAMP production and in subsequent GLP-1 production. Our findings suggest that the postprandial decrease in oxygen tension in the intestine attenuates GLP-1 secretion.
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Affiliation(s)
- Yoshitaka Kihira
- Department of Pharmacology, Institute of Health Biosciences, The University of Tokushima Graduate School
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21
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Pierre JF, Neuman JC, Brill AL, Brar HK, Thompson MF, Cadena MT, Connors KM, Busch RA, Heneghan AF, Cham CM, Jones EK, Kibbe CR, Davis DB, Groblewski GE, Kudsk KA, Kimple ME. The gastrin-releasing peptide analog bombesin preserves exocrine and endocrine pancreas morphology and function during parenteral nutrition. Am J Physiol Gastrointest Liver Physiol 2015; 309:G431-42. [PMID: 26185331 PMCID: PMC4572409 DOI: 10.1152/ajpgi.00072.2015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 07/02/2015] [Indexed: 01/31/2023]
Abstract
Stimulation of digestive organs by enteric peptides is lost during total parental nutrition (PN). Here we examine the role of the enteric peptide bombesin (BBS) in stimulation of the exocrine and endocrine pancreas during PN. BBS protects against exocrine pancreas atrophy and dysfunction caused by PN. BBS also augments circulating insulin levels, suggesting an endocrine pancreas phenotype. While no significant changes in gross endocrine pancreas morphology were observed, pancreatic islets isolated from BBS-treated PN mice showed a significantly enhanced insulin secretion response to the glucagon-like peptide-1 (GLP-1) agonist exendin-4, correlating with enhanced GLP-1 receptor expression. BBS itself had no effect on islet function, as reflected in low expression of BBS receptors in islet samples. Intestinal BBS receptor expression was enhanced in PN with BBS, and circulating active GLP-1 levels were significantly enhanced in BBS-treated PN mice. We hypothesized that BBS preserved islet function indirectly, through the enteroendocrine cell-pancreas axis. We confirmed the ability of BBS to directly stimulate intestinal enteroid cells to express the GLP-1 precursor preproglucagon. In conclusion, BBS preserves the exocrine and endocrine pancreas functions during PN; however, the endocrine stimulation is likely indirect, through the enteroendocrine cell-pancreas axis.
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Affiliation(s)
- Joseph F. Pierre
- 2Department of Surgery, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin; ,5Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, University of Chicago, Chicago, Illinois
| | - Joshua C. Neuman
- 4Interdisciplinary Graduate Program in Nutritional Sciences, University of Wisconsin-Madison College of Agriculture and Life Sciences, Madison, Wisconsin; and
| | - Allison L. Brill
- 3Division of Endocrinology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin;
| | - Harpreet K. Brar
- 3Division of Endocrinology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin;
| | - Mary F. Thompson
- 3Division of Endocrinology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin;
| | - Mark T. Cadena
- 3Division of Endocrinology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin;
| | - Kelsey M. Connors
- 3Division of Endocrinology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin;
| | - Rebecca A. Busch
- 2Department of Surgery, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin;
| | - Aaron F. Heneghan
- 2Department of Surgery, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin;
| | - Candace M. Cham
- 5Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, University of Chicago, Chicago, Illinois
| | - Elaina K. Jones
- 4Interdisciplinary Graduate Program in Nutritional Sciences, University of Wisconsin-Madison College of Agriculture and Life Sciences, Madison, Wisconsin; and
| | - Carly R. Kibbe
- 3Division of Endocrinology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin;
| | - Dawn B. Davis
- 1William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin; ,3Division of Endocrinology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin; ,4Interdisciplinary Graduate Program in Nutritional Sciences, University of Wisconsin-Madison College of Agriculture and Life Sciences, Madison, Wisconsin; and
| | - Guy E. Groblewski
- 4Interdisciplinary Graduate Program in Nutritional Sciences, University of Wisconsin-Madison College of Agriculture and Life Sciences, Madison, Wisconsin; and
| | - Kenneth A. Kudsk
- 1William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin; ,2Department of Surgery, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin;
| | - Michelle E. Kimple
- 1William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin; ,3Division of Endocrinology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin; ,4Interdisciplinary Graduate Program in Nutritional Sciences, University of Wisconsin-Madison College of Agriculture and Life Sciences, Madison, Wisconsin; and
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22
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Wellhauser L, Gojska NM, Belsham DD. Delineating the regulation of energy homeostasis using hypothalamic cell models. Front Neuroendocrinol 2015; 36:130-49. [PMID: 25223866 DOI: 10.1016/j.yfrne.2014.09.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 08/28/2014] [Accepted: 09/02/2014] [Indexed: 12/27/2022]
Abstract
Attesting to its intimate peripheral connections, hypothalamic neurons integrate nutritional and hormonal cues to effectively manage energy homeostasis according to the overall status of the system. Extensive progress in the identification of essential transcriptional and post-translational mechanisms regulating the controlled expression and actions of hypothalamic neuropeptides has been identified through the use of animal and cell models. This review will introduce the basic techniques of hypothalamic investigation both in vivo and in vitro and will briefly highlight the key advantages and challenges of their use. Further emphasis will be place on the use of immortalized models of hypothalamic neurons for in vitro study of feeding regulation, with a particular focus on cell lines proving themselves most fruitful in deciphering fundamental basics of NPY/AgRP, Proglucagon, and POMC neuropeptide function.
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Affiliation(s)
- Leigh Wellhauser
- Department of Physiology, University of Toronto, Toronto, Ontario M5G 1A8, Canada
| | - Nicole M Gojska
- Department of Physiology, University of Toronto, Toronto, Ontario M5G 1A8, Canada
| | - Denise D Belsham
- Departments of Physiology, Medicine and OB/GYN, University of Toronto, Toronto, Ontario M5G 1A8, Canada; Division of Cellular and Molecular Biology, Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario M5S 1A8, Canada.
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23
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Wang L, Luk CT, Cai EP, Schroer SA, Allister EM, Shi SY, Wheeler MB, Gaisano HY, Woo M. PTEN deletion in pancreatic α-cells protects against high-fat diet-induced hyperglucagonemia and insulin resistance. Diabetes 2015; 64:147-57. [PMID: 25092678 DOI: 10.2337/db13-1715] [Citation(s) in RCA: 16] [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: 11/13/2022]
Abstract
An aberrant increase in circulating catabolic hormone glucagon contributes to type 2 diabetes pathogenesis. However, mechanisms regulating glucagon secretion and α-cell mass are not well understood. In this study, we aimed to demonstrate that phosphatidylinositol 3-kinase (PI3K) signaling is an important regulator of α-cell function. Mice with deletion of PTEN, a negative regulator of this pathway, in α-cells show reduced circulating glucagon levels and attenuated l-arginine-stimulated glucagon secretion both in vivo and in vitro. This hypoglucagonemic state is maintained after high-fat-diet feeding, leading to reduced expression of hepatic glycogenolytic and gluconeogenic genes. These beneficial effects protected high-fat diet-fed mice against hyperglycemia and insulin resistance. The data demonstrate an inhibitory role of PI3K signaling on α-cell function and provide experimental evidence for enhancing α-cell PI3K signaling for diabetes treatment.
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Affiliation(s)
- Linyuan Wang
- Toronto General Research Institute, University Health Network, Toronto, ON, Canada Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Cynthia T Luk
- Toronto General Research Institute, University Health Network, Toronto, ON, Canada Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - Erica P Cai
- Toronto General Research Institute, University Health Network, Toronto, ON, Canada Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - Stephanie A Schroer
- Toronto General Research Institute, University Health Network, Toronto, ON, Canada
| | - Emma M Allister
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Sally Y Shi
- Toronto General Research Institute, University Health Network, Toronto, ON, Canada Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - Michael B Wheeler
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Herbert Y Gaisano
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Minna Woo
- Toronto General Research Institute, University Health Network, Toronto, ON, Canada Institute of Medical Science, University of Toronto, Toronto, ON, Canada Division of Endocrinology & Metabolism, Department of Medicine, University Health Network, Toronto, ON, Canada
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24
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Pais R, Zietek T, Hauner H, Daniel H, Skurk T. RANTES (CCL5) reduces glucose-dependent secretion of glucagon-like peptides 1 and 2 and impairs glucose-induced insulin secretion in mice. Am J Physiol Gastrointest Liver Physiol 2014; 307:G330-7. [PMID: 24875103 DOI: 10.1152/ajpgi.00329.2013] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Type 2 diabetes is associated with elevated circulating levels of the chemokine RANTES and with decreased plasma levels of the incretin hormone glucagon-like peptide 1 (GLP-1). GLP-1 is a peptide secreted from intestinal L-cells upon nutrient ingestion. It enhances insulin secretion from pancreatic β-cells and protects from β-cell loss but also promotes satiety and weight loss. In search of chemokines that may reduce GLP-1 secretion we identified RANTES and show that it reduces glucose-stimulated GLP-1 secretion in the human enteroendocrine cell line NCI-H716, blocked by the antagonist Met-RANTES, and in vivo in mice. RANTES exposure to mouse intestinal tissues lowers transport function of the intestinal glucose transporter SGLT1, and administration in mice reduces plasma GLP-1 and GLP-2 levels after an oral glucose load and thereby impairs insulin secretion. These data show that RANTES is involved in altered secretion of glucagon-like peptide hormones most probably acting through SGLT1, and our study identifies the RANTES-receptor CCR1 as a potential target in diabetes therapy.
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Affiliation(s)
- Ramona Pais
- ZIEL Research Center of Nutrition and Food Sciences, Nutritional Medicine, Technische Universität München, Freising, Germany; ZIEL Research Center of Nutrition and Food Sciences, Abteilung Biochemie, Technische Universität München, Freising, Germany; and
| | - Tamara Zietek
- ZIEL Research Center of Nutrition and Food Sciences, Abteilung Biochemie, Technische Universität München, Freising, Germany; and
| | - Hans Hauner
- ZIEL Research Center of Nutrition and Food Sciences, Nutritional Medicine, Technische Universität München, Freising, Germany; Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Hannelore Daniel
- ZIEL Research Center of Nutrition and Food Sciences, Abteilung Biochemie, Technische Universität München, Freising, Germany; and
| | - Thomas Skurk
- ZIEL Research Center of Nutrition and Food Sciences, Nutritional Medicine, Technische Universität München, Freising, Germany; Klinikum rechts der Isar, Technische Universität München, Munich, Germany
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25
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Tudurí E, Denroche HC, Kara JA, Asadi A, Fox JK, Kieffer TJ. Partial ablation of leptin signaling in mouse pancreatic α-cells does not alter either glucose or lipid homeostasis. Am J Physiol Endocrinol Metab 2014; 306:E748-55. [PMID: 24473435 DOI: 10.1152/ajpendo.00681.2013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The role of glucagon in the pathological condition of diabetes is gaining interest, and it has been recently reported that its action is essential for hyperglycemia to occur. Glucagon levels, which are elevated in some diabetic models, are reduced following leptin therapy. Likewise, hyperglycemia is corrected in type 1 diabetic mice treated with leptin, although the mechanisms have not been fully determined. A direct inhibitory effect of leptin on mouse and human α-cells has been demonstrated at the levels of electrical activity, calcium signaling, and glucagon secretion. In the present study we employed the Cre-loxP strategy to generate Lepr(flox/flox) Gcg-cre mice, which specifically lack leptin receptors in glucagon-secreting α-cells, to determine whether leptin resistance in α-cells contributes to hyperglucagonemia, and also whether leptin action in α-cells is required to improve glycemia in type 1 diabetes with leptin therapy. Immunohistochemical analysis of pancreas sections revealed Cre-mediated recombination in ∼ 43% of the α-cells. We observed that in vivo Lepr(flox/flox) Gcg-cre mice display normal glucose and lipid homeostasis. In addition, leptin administration in streptozotocin-induced diabetic Lepr(flox/flox) Gcg-cre mice restored euglycemia similarly to control mice. These findings suggest that loss of leptin receptor signaling in close to one-half of α-cells does not alter glucose metabolism in vivo, nor is it sufficient to prevent the therapeutic action of leptin in type 1 diabetes.
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MESH Headings
- Animals
- Cells, Cultured
- Diabetes Mellitus, Experimental/drug therapy
- Diabetes Mellitus, Experimental/genetics
- Diabetes Mellitus, Experimental/metabolism
- Diabetes Mellitus, Type 1/drug therapy
- Diabetes Mellitus, Type 1/genetics
- Diabetes Mellitus, Type 1/metabolism
- Female
- Gene Deletion
- Glucagon-Secreting Cells/metabolism
- Glucose/metabolism
- Homeostasis/genetics
- Leptin/metabolism
- Leptin/therapeutic use
- Lipid Metabolism/genetics
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic
- Receptors, Leptin/genetics
- Receptors, Leptin/metabolism
- Signal Transduction/genetics
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Affiliation(s)
- Eva Tudurí
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada; and
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26
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Berg JK, Kim EH, Li B, Joelsson B, Youssef NN. A randomized, double-blind, placebo-controlled, multiple-dose, parallel-group clinical trial to assess the effects of teduglutide on gastric emptying of liquids in healthy subjects. BMC Gastroenterol 2014; 14:25. [PMID: 24517114 PMCID: PMC3928318 DOI: 10.1186/1471-230x-14-25] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Accepted: 01/24/2014] [Indexed: 01/24/2023] Open
Abstract
Background Teduglutide, a recombinant analog of human glucagon-like peptide (GLP)-2, is a novel therapy recently approved for the treatment of adult patients with short bowel syndrome who are dependent on parenteral support. Previous studies assessing the effect of GLP-2 on gastric emptying in humans have yielded inconsistent results, with some studies showing no effect and others documenting a GLP-2–dependent delay in gastric emptying. The primary objective of this study was to assess the effect of teduglutide on gastric emptying of liquids in healthy subjects, as measured by the pharmacokinetics of acetaminophen. Methods This double-blind, parallel-group, single-center study enrolled and randomized 36 healthy subjects (22 men, 14 women) to receive subcutaneous doses of teduglutide 4 mg or placebo (2:1 ratio; 23:13) once daily on Days 1 through 10 in the morning. Gastric emptying of a mixed nutrient liquid meal was assessed by measuring acetaminophen levels predose and at 0.25, 0.5, 0.75, 1, 1.25, 1.5, 2, 3, 3.5, 4, 5, 6, 8, 10, 12, and 14 hours after administration of 1000 mg acetaminophen on Days 0 and 10. The primary study endpoint was a pharmacokinetic analysis of acetaminophen absorption in subjects receiving teduglutide or placebo. Results No significant differences in gastric emptying of liquids (acetaminophen area under the concentration [AUC] vs time curve from time 0 to the last measurable concentration, AUC extrapolated to infinity, maximum concentration [Cmax], and time to Cmax) were observed on Day 10 in subjects receiving teduglutide 4 mg versus subjects receiving placebo. There were no serious adverse events (AEs), deaths, or discontinuations due to an AE reported during the study. Conclusions Teduglutide 4 mg/day for 10 days does not affect gastric emptying of liquids in healthy subjects as measured by acetaminophen pharmacokinetics. No unexpected safety signals were observed. Trial registration This study was registered at ClinicalTrials.gov, identifier NCT01209351.
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Affiliation(s)
- Jolene Kay Berg
- DaVita Clinical Research, 825 S, 8th Street, Suite 300, Minneapolis, MN 55404, USA.
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27
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Nguyen AT, Mandard S, Dray C, Deckert V, Valet P, Besnard P, Drucker DJ, Lagrost L, Grober J. Lipopolysaccharides-mediated increase in glucose-stimulated insulin secretion: involvement of the GLP-1 pathway. Diabetes 2014; 63:471-82. [PMID: 24186868 DOI: 10.2337/db13-0903] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Lipopolysaccharides (LPS) of the cell wall of gram-negative bacteria trigger inflammation, which is associated with marked changes in glucose metabolism. Hyperglycemia is frequently observed during bacterial infection and it is a marker of a poor clinical outcome in critically ill patients. The aim of the current study was to investigate the effect of an acute injection or continuous infusion of LPS on experimentally induced hyperglycemia in wild-type and genetically engineered mice. The acute injection of a single dose of LPS produced an increase in glucose disposal and glucose-stimulated insulin secretion (GSIS). Continuous infusion of LPS through mini-osmotic pumps was also associated with increased GSIS. Finally, manipulation of LPS detoxification by knocking out the plasma phospholipid transfer protein (PLTP) led to increased glucose disposal and GSIS. Overall, glucose tolerance and GSIS tests supported the hypothesis that mice treated with LPS develop glucose-induced hyperinsulinemia. The effects of LPS on glucose metabolism were significantly altered as a result of either the accumulation or antagonism of glucagon-like peptide 1 (GLP-1). Complementary studies in wild-type and GLP-1 receptor knockout mice further implicated the GLP-1 receptor-dependent pathway in mediating the LPS-mediated changes in glucose metabolism. Hence, enhanced GLP-1 secretion and action underlies the development of glucose-mediated hyperinsulinemia associated with endotoxemia.
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Affiliation(s)
- Anh Thoai Nguyen
- INSERM UMR866-LabEx LipSTIC, Faculté de Médecine, Université de Bourgogne, Dijon, France
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28
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Koole C, Savage EE, Christopoulos A, Miller LJ, Sexton PM, Wootten D. Minireview: Signal bias, allosterism, and polymorphic variation at the GLP-1R: implications for drug discovery. Mol Endocrinol 2013; 27:1234-44. [PMID: 23864649 DOI: 10.1210/me.2013-1116] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The glucagon-like peptide-1 receptor (GLP-1R) controls the physiological responses to the incretin hormone glucagon-like peptide-1 and is a major therapeutic target for the treatment of type 2 diabetes, owing to the broad range of effects that are mediated upon its activation. These include the promotion of glucose-dependent insulin secretion, increased insulin biosynthesis, preservation of β-cell mass, improved peripheral insulin action, and promotion of weight loss. Regulation of GLP-1R function is complex, with multiple endogenous and exogenous peptides that interact with the receptor that result in the activation of numerous downstream signaling cascades. The current understanding of GLP-1R signaling and regulation is limited, with the desired spectrum of signaling required for the ideal therapeutic outcome still to be determined. In addition, there are several single-nucleotide polymorphisms (used in this review as defining a natural change of single nucleotide in the receptor sequence; clinically, this is viewed as a single-nucleotide polymorphism only if the frequency of the mutation occurs in 1% or more of the population) distributed within the coding sequence of the receptor protein that have the potential to produce differential responses for distinct ligands. In this review, we discuss the current understanding of GLP-1R function, in particular highlighting recent advances in the field on ligand-directed signal bias, allosteric modulation, and probe dependence and the implications of these behaviors for drug discovery and development.
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Affiliation(s)
- Cassandra Koole
- Department of Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
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29
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Chepurny OG, Bertinetti D, Diskar M, Leech CA, Afshari P, Tsalkova T, Cheng X, Schwede F, Genieser HG, Herberg FW, Holz GG. Stimulation of proglucagon gene expression by human GPR119 in enteroendocrine L-cell line GLUTag. Mol Endocrinol 2013; 27:1267-82. [PMID: 23798572 DOI: 10.1210/me.2013-1029] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
GPR119 is a G protein-coupled receptor expressed on enteroendocrine L-cells that synthesize and secrete the incretin hormone glucagon-like peptide-1 (GLP-1). Although GPR119 agonists stimulate L-cell GLP-1 secretion, there is uncertainty concerning whether GLP-1 biosynthesis is under the control of GPR119. Here we report that GPR119 is functionally coupled to increased proglucagon (PG) gene expression that constitutes an essential first step in GLP-1 biosynthesis. Using a mouse L-cell line (GLUTag) that expresses endogenous GPR119, we demonstrate that PG gene promoter activity is stimulated by GPR119 agonist AS1269574. Surprisingly, transfection of GLUTag cells with recombinant human GPR119 (hGPR119) results in a constitutive and apparently ligand-independent increase of PG gene promoter activity and PG mRNA content. These constitutive actions of hGPR119 are mediated by cAMP-dependent protein kinase (PKA) but not cAMP sensor Epac2. Thus, the constitutive action of hGPR119 to stimulate PG gene promoter activity is diminished by: 1) a dominant-negative Gαs protein, 2) a dominant-negative PKA regulatory subunit, and 3) a dominant-negative A-CREB. Interestingly, PG gene promoter activity is stimulated by 6-Bn-cAMP-AM, a cAMP analog that selectively activates α and β isoforms of type II, but not type I PKA regulatory subunits expressed in GLUTag cells. Finally, our analysis reveals that a specific inhibitor of Epac2 activation (ESI-05) fails to block the stimulatory action of 6-Bn-cAMP-AM at the PG gene promoter, nor is PG gene promoter activity stimulated by: 1) a constitutively active Epac2, or 2) cAMP analogs that selectively activate Epac proteins. Such findings are discussed within the context of ongoing controversies concerning the relative contributions of PKA and Epac2 to the control of PG gene expression.
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Affiliation(s)
- Oleg G Chepurny
- Department of Medicine, State University of New York, Upstate Medical University, Syracuse, New York 13210, USA
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30
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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: 5.7] [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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31
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Cyclic AMP and PKA: how can a lot of good come from the potentially bad? : editorial to: "phosphodiesterase III inhibition increases cAMP levels and augments the infarct size limiting effect of a DPP-4 inhibitor in mice with type-2 diabetes mellitus" by Y. Birnbaum et al. Cardiovasc Drugs Ther 2013; 26:435-6. [PMID: 23054030 DOI: 10.1007/s10557-012-6418-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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32
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Xiong Y, Swaminath G, Cao Q, Yang L, Guo Q, Salomonis H, Lu J, Houze JB, Dransfield PJ, Wang Y, Liu JJ, Wong S, Schwandner R, Steger F, Baribault H, Liu L, Coberly S, Miao L, Zhang J, Lin DCH, Schwarz M. Activation of FFA1 mediates GLP-1 secretion in mice. Evidence for allosterism at FFA1. Mol Cell Endocrinol 2013; 369:119-29. [PMID: 23403053 DOI: 10.1016/j.mce.2013.01.009] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2012] [Revised: 01/03/2013] [Accepted: 01/14/2013] [Indexed: 01/04/2023]
Abstract
FFA1 (GPR40) and GPR120 are G-protein-coupled receptors activated by long-chain fatty acids. FFA1 is expressed in pancreatic β-cells, where it regulates glucose-dependent insulin secretion, and GPR120 has been implicated in mediating GLP-1 secretion. We show here that FFA1 co-localizes with GLP-1 in enteroendocrine cells and plays a critical role in glucose management by mediating GLP-1 secretion in vivo. Corn oil induces GLP-1 secretion in wild type mice and in GPR120-/- mice, but not in FFA1-/- mice. α-Linolenic acid, an endogenous ligand of FFA1, induces GLP-1 secretion in GLUTag cells and in primary fetal mouse intestinal cells. Synthetic partial FFA1 agonists do not stimulate GLP-1 secretion in mice, but partial and full agonists combined function cooperatively to enhance receptor activation and GLP-1 secretion both in vitro and in vivo. We conclude that allosterism at FFA1 can contribute to postprandial glucose management by stimulating insulin secretion via an extrapancreatic mechanism of action, and that GPR120 in GLP-1 secretion requires further investigation.
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Affiliation(s)
- Yumei Xiong
- Department of Metabolic Disorders, Amgen Inc., South San Francisco, CA 94080, USA
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33
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Ojo OO, Conlon JM, Flatt PR, Abdel-Wahab YHA. Frog skin peptides (tigerinin-1R, magainin-AM1, -AM2, CPF-AM1, and PGla-AM1) stimulate secretion of glucagon-like peptide 1 (GLP-1) by GLUTag cells. Biochem Biophys Res Commun 2013; 431:14-8. [PMID: 23291176 DOI: 10.1016/j.bbrc.2012.12.116] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Accepted: 12/17/2012] [Indexed: 12/25/2022]
Abstract
Skin secretions of several frog species contain host-defense peptides with multiple biological activities including in vitro and in vivo insulin-releasing actions. This study investigates the effects of tigerinin-1R from Hoplobatrachus rugulosus (Dicroglossidae) and magainin-AM1, magainin-AM2, caerulein precursor fragment (CPF-AM1) and peptide glycine leucine amide (PGLa-AM1) from Xenopus amieti (Pipidae) on GLP-1 secretion from GLUTag cells. Tigerinin-1R showed the highest potency producing a significant (P<0.05) increase in GLP-1 release at a concentration of 0.1nM for the cyclic peptide and 0.3nM for the reduced form. All peptides from X. amieti significantly (P<0.05) stimulated GLP-1 release at concentrations ⩾300nM with magainin-AM2 exhibiting the greatest potency (minimum concentration producing a significant stimulation=1nM). The maximum stimulatory response (3.2-fold of basal rate, P<0.001) was produced by CPF-AM1 at a concentration of 3μM. No peptide stimulated release of the cytosolic enzyme, lactate dehydrogenase from GLUTag cells at concentrations up to 3μM indicating that the integrity of the plasma membrane had been preserved. The data indicate that frog skin peptides, by stimulating GLP-1 release as well as direct effects on insulin secretion, show therapeutic potential as agents for the treatment of type 2 diabetes.
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Affiliation(s)
- O O Ojo
- School of Biomedical Sciences, University of Ulster, Coleraine BT52 1SA, UK
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34
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Coskun T, O'Farrell LS, Syed SK, Briere DA, Beavers LS, Dubois SL, Michael MD, Franciskovich JB, Barrett DG, Efanov AM. Activation of prostaglandin E receptor 4 triggers secretion of gut hormone peptides GLP-1, GLP-2, and PYY. Endocrinology 2013; 154:45-53. [PMID: 23142807 DOI: 10.1210/en.2012-1446] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Prostaglandins E1 and E2 are synthesized in the intestine and mediate a range of gastrointestinal functions via activation of the prostanoid E type (EP) family of receptors. We examined the potential role of EP receptors in the regulation of gut hormone secretion from L cells. Analysis of mRNA expression in mouse enteroendocrine GLUTag cells demonstrated the abundant expression of EP4 receptor, whereas expression of other EP receptors was much lower. Prostaglandin E1 and E2, nonselective agonists for all EP receptor subtypes, triggered glucagon like peptide 1 (GLP-1) secretion from GLUTag cells, as did the EP4-selective agonists CAY10580 and TCS2510. The effect of EP4 agonists on GLP-1 secretion was blocked by incubation of cells with the EP4-selective antagonist L161,982 or by down-regulating EP4 expression with specific small interfering RNA. Regulation of gut hormone secretion with EP4 agonists was further studied in mice. Administration of EP4 agonists to mice produced a significant elevation of plasma levels of GLP-1, glucagon like peptide 2 (GLP-2) and peptide YY (PYY), whereas gastric inhibitory peptide (GIP) levels were not increased. Thus, our data demonstrate that activation of the EP4 receptor in enteroendocrine L cells triggers secretion of gut hormones.
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Affiliation(s)
- Tamer Coskun
- Lilly Research Laboratories, Lilly Corporate Center, Indianapolis, IN 46285, USA
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35
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Janssen P, Rotondo A, Mulé F, Tack J. Review article: a comparison of glucagon-like peptides 1 and 2. Aliment Pharmacol Ther 2013; 37:18-36. [PMID: 23121085 DOI: 10.1111/apt.12092] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Revised: 07/09/2012] [Accepted: 09/29/2012] [Indexed: 12/18/2022]
Abstract
BACKGROUND Recent advancements in understanding the roles and functions of glucagon-like peptide 1 (GLP-1) and 2 (GLP-2) have provided a basis for targeting these peptides in therapeutic strategies. AIM To summarise the preclinical and clinical research supporting the discovery of new therapeutic molecules targeting GLP-1 and GLP-2. METHODS This review is based on a comprehensive PubMed search, representing literature published during the past 30 years related to GLP-1 and GLP-2. RESULTS Although produced and secreted together primarily from L cells of the intestine in response to ingestion of nutrients, GLP-1 and GLP-2 exhibit distinctive biological functions that are governed by the expression of their respective receptors, GLP-1R and GLP-2R. Through widespread expression in the pancreas, intestine, nervous tissue, et cetera, GLP-1Rs facilitates an incretin effect along with effects on appetite and satiety. GLP-1 analogues resistant to degradation by dipeptidyl peptidase-IV and inhibitors of dipeptidyl peptidase-IV have been developed to aid treatment of diabetes and obesity. The GLP-2R is expressed almost exclusively in the stomach and bowel. The most apparent role for GLP-2 is its promotion of growth and function of intestinal mucosa, which has been targeted for therapies that promote repair and adaptive growth. These are used as treatments for intestinal failure and related conditions. CONCLUSIONS Our growing understanding of the biology and function of GLP-1, GLP-2 and corresponding receptors has fostered further discovery of fundamental biological function as well as new categories of potent therapeutic medicines.
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Affiliation(s)
- P Janssen
- Translational Research Center for Gastrointestinal Disorders, University of Leuven, Belgium
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36
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Flock GB, Cao X, Maziarz M, Drucker DJ. Activation of enteroendocrine membrane progesterone receptors promotes incretin secretion and improves glucose tolerance in mice. Diabetes 2013; 62:283-90. [PMID: 22933106 PMCID: PMC3526055 DOI: 10.2337/db12-0601] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Accepted: 06/28/2012] [Indexed: 12/13/2022]
Abstract
Glucagon-like peptide-1 (GLP-1) secretion is classically regulated by ingested nutrients. To identify novel molecular targets controlling incretin secretion, we analyzed enteroendocrine cell pathways important for hormone biosynthesis and secretion. We demonstrate that progesterone increases GLP-1 secretion and extracellular signal-related kinase 1/2 (ERK1/2) phosphorylation in enteroendocrine GLUTag cells via mechanisms sensitive to the mitogen-activated protein kinase inhibitor U0126. The stimulatory effects of progesterone (P4) or the synthetic progestin R5020 on ERK1/2 phosphorylation were independent of the classical progesterone receptor antagonist RU486. Furthermore, a cell-impermeable BSA-progesterone conjugate rapidly increased ERK1/2 phosphorylation and GLP-1 secretion. Knockdown of the membrane progesterone receptors Paqr5 or Paqr7 in GLUTag cells eliminated the stimulatory effect of R5020 and progesterone on GLP-1 secretion. Enteral progesterone administration increased plasma levels of GLP-1, glucose-dependent insulinotropic polypeptide (GIP), and insulin, and improved oral glucose tolerance in an RU486-insensitve manner in mice: however, systemic progesterone exposure did not improve glucose homeostasis. Unexpectedly, the glucoregulatory actions of enteral progesterone did not require classical incretin receptor signaling and were preserved in Glp1r(-/-) and Glp1r(-/-):Gipr(-/-) mice. Intestine-restricted activation of membrane progesterone receptors may represent a novel approach for stimulation of incretin hormone secretion and control of glucose homeostasis.
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Affiliation(s)
- Grace B. Flock
- Department of Medicine, Institute of Medical Sciences, Samuel Lunenfeld Research Institute, University of Toronto, Toronto, Ontario, Canada
| | - Xiemin Cao
- Department of Medicine, Institute of Medical Sciences, Samuel Lunenfeld Research Institute, University of Toronto, Toronto, Ontario, Canada
| | - Marlena Maziarz
- Department of Medicine, Institute of Medical Sciences, Samuel Lunenfeld Research Institute, University of Toronto, Toronto, Ontario, Canada
| | - Daniel J. Drucker
- Department of Medicine, Institute of Medical Sciences, Samuel Lunenfeld Research Institute, University of Toronto, Toronto, Ontario, Canada
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37
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Dalvi PS, Erbiceanu FD, Irwin DM, Belsham DD. Direct regulation of the proglucagon gene by insulin, leptin, and cAMP in embryonic versus adult hypothalamic neurons. Mol Endocrinol 2012; 26:1339-55. [PMID: 22669740 DOI: 10.1210/me.2012-1049] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The proglucagon gene is expressed not only in the pancreas and intestine but also in the hypothalamus. Proglucagon-derived peptides have emerged as potential regulators of energy homeostasis. Whether leptin, insulin, or cAMP activation controls proglucagon gene expression in the hypothalamus is not known. A key reason for this has been the inaccessibility of hypothalamic proglucagon-expressing neurons and the lack of suitable neuronal cell lines. Herein we describe the mechanisms involved in the direct regulation of the proglucagon gene by insulin, leptin, and cAMP in hypothalamic cell models. Insulin, through an Akt-dependent manner, significantly induced proglucagon mRNA expression by 70% in adult-derived mHypoA-2/10 neurons and significantly suppressed it by 45% in embryonic-derived mHypoE-39 neurons. Leptin, via the Janus kinase-2/ signal transducer and activator of transcription-3 pathway, caused an initial increase by 66 and 43% at 1 h followed by a decrease by 45 and 34% at 12 h in mHypoA-2/10 and mHypoE-39 cells, respectively. Furthermore, cAMP activation by forskolin up-regulated proglucagon expression by 87% in mHypoE-39 neurons and increased proglucagon mRNA, through Epac activation, in the mHypoE-20/2 neurons. Specific regions of the proglucagon promoter were regulated by cAMP signaling, as determined by transient transfections, whereas mRNA stability assays demonstrate that insulin and leptin increase proglucagon mRNA stability in the adult cells. These findings suggest that insulin, leptin, and cAMP act directly, but differentially, on specific hypothalamic neurons to regulate proglucagon gene expression. Because proglucagon-derived peptides are potential regulators of energy homeostasis, an understanding of hypothalamic proglucagon neurons is important to further expand our knowledge of alternative feeding circuits.
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Affiliation(s)
- Prasad S Dalvi
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
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38
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Harach T, Pols TWH, Nomura M, Maida A, Watanabe M, Auwerx J, Schoonjans K. TGR5 potentiates GLP-1 secretion in response to anionic exchange resins. Sci Rep 2012; 2:430. [PMID: 22666533 PMCID: PMC3362799 DOI: 10.1038/srep00430] [Citation(s) in RCA: 134] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Accepted: 05/14/2012] [Indexed: 12/18/2022] Open
Abstract
Anionic exchange resins are bona fide cholesterol-lowering agents with glycemia lowering actions in diabetic patients. Potentiation of intestinal GLP-1 secretion has been proposed to contribute to the glycemia lowering effect of these non-systemic drugs. Here, we show that resin exposure enhances GLP-1 secretion and improves glycemic control in diet-induced animal models of “diabesity”, effects which are critically dependent on TGR5, a G protein-coupled receptor that is activated by bile acids. We identified the colon as a major source of GLP-1 secretion after resin treatment. Furthermore, we demonstrate that the boost in GLP-1 release by resins is due to both enhanced TGR5-dependent production of the precursor transcript of GLP-1 as well as to the local enrichment of TGR5 agonists in the colon. Thus, TGR5 represents an essential component in the pathway mediating the enhanced GLP-1 release in response to anionic exchange resins.
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Affiliation(s)
- Taoufiq Harach
- Laboratory of Integrative and Systems Physiology-LISP, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
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Mulherin AJ, Oh AH, Kim H, Grieco A, Lauffer LM, Brubaker PL. Mechanisms underlying metformin-induced secretion of glucagon-like peptide-1 from the intestinal L cell. Endocrinology 2011; 152:4610-9. [PMID: 21971158 DOI: 10.1210/en.2011-1485] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Glucagon-like peptide-1(7-36NH2) (GLP-1) is secreted by the intestinal L cell in response to both nutrient and neural stimulation, resulting in enhanced glucose-dependent insulin secretion. GLP-1 is therefore an attractive therapeutic for the treatment of type 2 diabetes. The antidiabetic drug, metformin, is known to increase circulating GLP-1 levels, although its mechanism of action is unknown. Direct effects of metformin (5-2000 μm) or another AMP kinase activator, aminoimidazole carboxamide ribonucleotide (100-1000 μm) on GLP-1 secretion were assessed in murine human NCI-H716, and rat FRIC L cells. Neither agent stimulated GLP-1 secretion in any model, despite increasing AMP kinase phosphorylation (P < 0.05-0.01). Treatment of rats with metformin (300 mg/kg, per os) or aminoimidazole carboxamide ribonucleotide (250 mg/kg, sc) increased plasma total GLP-1 over 2 h, reaching 37 ± 9 and 29 ± 9 pg/ml (P < 0.001), respectively, compared with basal (7 ± 1 pg/ml). Plasma activity of the GLP-1-degrading enzyme, dipeptidylpeptidase-IV, was not affected by metformin treatment. Pretreatment with the nonspecific muscarinic antagonist, atropine (1 mg/kg, iv), decreased metformin-induced GLP-1 secretion by 55 ± 11% (P < 0.05). Pretreatment with the muscarinic (M) 3 receptor antagonist, 1-1-dimethyl-4-diphenylacetoxypiperidinium iodide (500 μg/kg, iv), also decreased the GLP-1 area under curve, by 48 ± 8% (P < 0.05), whereas the antagonists pirenzepine (M1) and gallamine (M2) had no effect. Furthermore, chronic bilateral subdiaphragmatic vagotomy decreased basal secretion compared with sham-operated animals (7 ± 1 vs. 13 ± 1 pg/ml, P < 0.001) but did not alter the GLP-1 response to metformin. In contrast, pretreatment with the gastrin-releasing peptide antagonist, RC-3095 (100 μg/kg, sc), reduced the GLP-1 response to metformin, by 55 ± 6% (P < 0.01) at 30 min. These studies elucidate the mechanism underlying metformin-induced GLP-1 secretion and highlight the benefits of using metformin with dipeptidylpeptidase-IV inhibitors in patients with type 2 diabetes.
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Affiliation(s)
- Andrew J Mulherin
- Department of Physiology, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada
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Daoudi M, Hennuyer N, Borland MG, Touche V, Duhem C, Gross B, Caiazzo R, Kerr-Conte J, Pattou F, Peters JM, Staels B, Lestavel S. PPARβ/δ activation induces enteroendocrine L cell GLP-1 production. Gastroenterology 2011; 140:1564-74. [PMID: 21300064 DOI: 10.1053/j.gastro.2011.01.045] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2010] [Revised: 01/06/2011] [Accepted: 01/20/2011] [Indexed: 12/25/2022]
Abstract
BACKGROUND & AIMS Glucagon-like peptide (GLP)-1, an intestinal incretin produced by L cells through proglucagon processing, is secreted after nutrient ingestion and acts on endocrine pancreas beta cells to enhance insulin secretion. Peroxisome proliferator-activated receptor (PPAR) β/δ is a nuclear receptor that improves glucose homeostasis and pancreas islet function in diabetic animal models. Here, we investigated whether PPARβ/δ activation regulates L cell GLP-1 production. METHODS Proglucagon regulation and GLP-1 release were evaluated in murine GLUTag and human NCI-H716 L cells and in vivo using wild-type, PPARβ/δ-null, and ob/ob C57Bl/6 mice treated with the PPARβ/δ synthetic agonists GW501516 or GW0742. RESULTS PPARβ/δ activation increased proglucagon expression and enhanced glucose- and bile acid-induced GLP-1 release by intestinal L cells in vitro and ex vivo in human jejunum. In vivo treatment with GW0742 increased proglucagon messenger RNA levels in the small intestine in wild-type but not in PPARβ/δ-deficient mice. Treatment of wild-type and ob/ob mice with GW501516 enhanced the increase in plasma GLP-1 level after an oral glucose load and improved glucose tolerance. Concomitantly, proglucagon and GLP-1 receptor messenger RNA levels increased in the small intestine and pancreas, respectively. Finally, PPARβ/δ agonists activate the proglucagon gene transcription by interfering with the β-catenin/TCF-4 pathway. CONCLUSIONS Our data show that PPARβ/δ activation potentiates GLP-1 production by the small intestine. Pharmacologic targeting of PPARβ/δ is a promising approach in the treatment of patients with type 2 diabetes mellitus, especially in combination with dipeptidyl peptidase IV inhibitors.
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From Enteroglucagon to the Glucagon-Like Peptides, GLP-1 and GLP-2. Can J Diabetes 2010. [DOI: 10.1016/s1499-2671(10)43017-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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42
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Yu Z, Jin T. New insights into the role of cAMP in the production and function of the incretin hormone glucagon-like peptide-1 (GLP-1). Cell Signal 2009; 22:1-8. [PMID: 19772917 DOI: 10.1016/j.cellsig.2009.09.032] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2009] [Revised: 09/10/2009] [Accepted: 09/13/2009] [Indexed: 12/25/2022]
Abstract
The proglucagon gene (gcg) encodes both glucagon and glucagon-like peptide-1 (GLP-1), produced in pancreatic alpha cells and intestinal endocrine L cells, respectively. The incretin hormone GLP-1 stimulates insulin secretion and pro-insulin gene transcription. GLP-1 also enhances pancreatic beta-cell proliferation, inhibits cell apoptosis, and has been utilized in the trans-differentiation of insulin producing cells. A long-term effective GLP-1 receptor agonist, Byetta, has now been developed as the drug in treating type II diabetes and potentially other metabolic disorders. The expression of gcg and the production of GLP-1 can be activated by the elevation of the second messenger cyclic AMP (cAMP). Recent studies suggest that in addition to protein kinase A (PKA), exchange protein activated by cAMP (Epac), another effector of cAMP, and the crosstalk between PKA and the Wnt signaling pathway, are involved in cAMP-stimulated gcg transcription and GLP-1 production as well. Finally, functions of GLP-1 in pancreatic beta cells are also mediated by PKA, Epac, as well as the effector of the Wnt signaling pathway. Together, these novel findings bring us a new insight into the role of cAMP in the production and function of the incretin hormone GLP-1.
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Affiliation(s)
- Zhiwen Yu
- Banting and Best Diabetes Centre, University of Toronto, Canada
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43
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Islam D, Zhang N, Wang P, Li H, Brubaker PL, Gaisano HY, Wang Q, Jin T. Epac is involved in cAMP-stimulated proglucagon expression and hormone production but not hormone secretion in pancreatic alpha- and intestinal L-cell lines. Am J Physiol Endocrinol Metab 2009; 296:E174-81. [PMID: 18854429 DOI: 10.1152/ajpendo.90419.2008] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Both Epac and PKA are effectors of the second messenger cAMP. Utilizing an exchange protein directly activated by cAMP (Epac) pathway-specific cAMP analog (ESCA), we previously reported that Epac signaling regulates proglucagon gene (gcg) expression in the glucagon-like peptide-1 (GLP-1)-producing intestinal endocrine L-cell lines GLUTag and STC-1. We now show that Epac-2 is also expressed in glucagon-producing pancreatic alpha-cell lines, including PKA-deficient InR1-G9 cells, and that ESCA stimulates gcg promoter and mRNA expression in the InR1-G9 cells. Using a dominant-negative Epac-2 expression plasmid (Epac-2DN), we found that Epac inhibition attenuated forskolin-stimulated gcg promoter expression in the PKA-active STC-1 cell line and blocked forskolin-stimulated gcg promoter expression in the InR1-G9 cells. Consistently, ESCA was shown to stimulate glucagon and GLP-1 production in the InR1-G9 and GLUTag cell lines, respectively. Surprisingly, ESCA treatment did not show a notable stimulation of glucagon or GLP-1 secretion from these two cell lines. This is in contrast to its ability to stimulate insulin secretion from the pancreatic INS-1 beta-cell line. Our findings suggest that Epac is selectively involved in peptide hormone secretion in pancreatic and intestinal endocrine cells and that distinct signaling cascades are involved in stimulating production vs. secretion of glucagon and GLP-1 in response to cAMP elevation.
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Affiliation(s)
- Diana Islam
- Division of Cell and Molecular Biology, Toronto General Research Institute, University Health Network, 101 College St., Toronto, Ontario M5G 1L7
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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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45
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Chen L, Wang P, Andrade CF, Zhao IY, Dubé PE, Brubaker PL, Liu M, Jin T. PKA independent and cell type specific activation of the expression of caudal homeobox gene Cdx-2 by cyclic AMP. FEBS J 2005; 272:2746-59. [PMID: 15943809 DOI: 10.1111/j.1742-4658.2005.04694.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Cdx-2 is a transactivator for the proglucagon gene in pancreatic and intestinal endocrine cells. Cdx-2 is also expressed in differentiated intestinal epithelia of nonendocrine origin. Cdx-2-/- mice are embryonic lethal, while Cdx-2+/- mutants show multiple malfunctions including the formation of intestinal polyps. Within the polyps, the remaining wild type Cdx-2 allele ceases its expression, while the expression of both Cdx-2 and proglucagon in the endocrine cells remains unaltered, indicating that Cdx-2 could be haplo-insufficient for nonendocrine cells, but not for proglucagon producing endocrine cells. We propose that mechanisms underlying Cdx-2 expression and auto-regulation [Xu F, Li H & Jin T (1999), J Biol Chem274, 34310-34316] differ in these two types of cells. We show here that forskolin and cAMP upregulate Cdx-2 expression in proglucagon producing cells, but not in colon cancer cells and primary intestinal cell cultures. It is unlikely that the activation is mainly mediated by PKA, because the activation was observed in a PKA deficient cell line. Co-transfecting a dominant negative Ras expression plasmid substantially repressed the Cdx-2 promoter, in contrast to a previous finding that Ras is a negative factor for Cdx-2 expression in colon cancer cells. Furthermore, forskolin activated ERK1/2 phosphorylation in the endocrine cells, and attenuation of ERK1/2 phosphorylation by its inhibitor is associated with attenuated Cdx-2 expression. Finally, an Epac pathway specific cAMP analogue stimulated both ERK1/2 phosphorylation and Cdx-2 expression. Taken together, our observations suggest that Cdx-2 expression is regulated by the second messenger cAMP, cell-type specifically, via the Epac pathway.
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Affiliation(s)
- Liang Chen
- Division of Cell and Molecular Biology, Toronto General Research Institute, University Health Network, Toronto, Ontario
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46
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Koehler JA, Yusta B, Drucker DJ. The HeLa Cell Glucagon-Like Peptide-2 Receptor Is Coupled to Regulation of Apoptosis and ERK1/2 Activation through Divergent Signaling Pathways. Mol Endocrinol 2005; 19:459-73. [PMID: 15471943 DOI: 10.1210/me.2004-0196] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
AbstractGlucagon-like peptide-2 (GLP-2) regulates proliferative and cytoprotective pathways in the intestine; however GLP-2 receptor (GLP-2R) signal transduction remains poorly understood, and cell lines that express the endogenous GLP-2R have not yet been isolated. We have now identified several expressed sequence tags from human cervical carcinoma cDNA libraries that correspond to GLP-2R nucleotide sequences. GLP-2R mRNA transcripts were detected by RT-PCR in two human cervical carcinoma cell lines, including HeLa cells. GLP-2 increased cAMP accumulation and activated ERK1/2 in HeLa cells transiently expressing the cloned human HeLa cell GLP-2R cDNA. However, the GLP-2R-induced activation of ERK1/2 was not mediated through Gαs, adenylyl cyclase, or transactivation of the epidermal growth factor receptor, but was pertussis toxin sensitive, inhibited by dominant negative Ras, and dependent on βγ-subunits. GLP-2 also induced a significant increase in bromodeoxyuridine incorporation that was blocked by dominant negative Ras. Furthermore, GLP-2 inhibited HeLa cell apoptosis induced by LY294002 in a protein kinase A-dependent, but ERK-independent, manner. These findings demonstrate that the HeLa cell GLP-2R differentially signals through both Gαs/cAMP- and Gi/Go-dependent pathways, illustrating for the first time that the GLP-2R is capable of coupling to multiple heterotrimeric G proteins defining distinct GLP-2R-dependent biological actions.
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MESH Headings
- Adenylyl Cyclases/metabolism
- Apoptosis
- Blotting, Southern
- Blotting, Western
- Bromodeoxyuridine/pharmacology
- Cell Line, Tumor
- Cell Survival
- Cervix Uteri/metabolism
- Chromones/pharmacology
- Cloning, Molecular
- Cyclic AMP/metabolism
- DNA/metabolism
- DNA, Complementary/metabolism
- Dimerization
- Dose-Response Relationship, Drug
- Electrophoresis, Polyacrylamide Gel
- Enzyme Activation
- Enzyme Inhibitors/pharmacology
- ErbB Receptors/metabolism
- Female
- Gene Library
- Genes, Dominant
- Glucagon-Like Peptide-1 Receptor
- HeLa Cells
- Humans
- Immunohistochemistry
- Luciferases/metabolism
- Mitogen-Activated Protein Kinase 1/metabolism
- Mitogen-Activated Protein Kinase 3/metabolism
- Models, Biological
- Morpholines/pharmacology
- Pertussis Toxin/pharmacology
- Plasmids/metabolism
- Receptors, Glucagon/chemistry
- Receptors, Glucagon/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Signal Transduction
- Transcriptional Activation
- Transfection
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Affiliation(s)
- J A Koehler
- Department of Medicine, General Hospital, Banting and Best Diabetes Centre, 200 Elizabeth Street, MBRW4R-402, Toronto, Canada M5G 2C4
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47
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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: 14.9] [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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48
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Gevrey JC, Malapel M, Philippe J, Mithieux G, Chayvialle JA, Abello J, Cordier-Bussat M. Protein hydrolysates stimulate proglucagon gene transcription in intestinal endocrine cells via two elements related to cyclic AMP response element. Diabetologia 2004; 47:926-36. [PMID: 15085339 DOI: 10.1007/s00125-004-1380-0] [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] [Received: 10/02/2003] [Accepted: 02/03/2004] [Indexed: 10/26/2022]
Abstract
AIMS/HYPOTHESIS Protein hydrolysates (peptones) increase not only glucagon-like peptide-1 (GLP-1) secretion but also transcription of the proglucagon ( PG) gene in the intestine. The critical physiological roles of gut-derived GLPs raised hope for their therapeutic use in several disorders, especially GLP-1 in diabetes. We aimed to investigate the molecular mechanisms involved in this nutrient- PG gene interaction. METHODS Wild-type and mutated PG promoter fragments fused to the luciferase reporter gene were transfected into enteroendocrine STC-1 cells, which were then either treated or not with peptones. Co-transfection with expression vectors of dominant-negative forms of cAMP response element binding protein (CREB) and protein kinase A (PKA) proteins were performed, as well as electrophoresis mobility shift assays. RESULTS Deletion analysis showed that the promoter region spanning between -350 and -292 bp was crucial for the transcriptional stimulation induced by peptones. Site-directed mutagenesis of the canonical cAMP response element (CRE(PG)) and of the adjacent putative CRE site (CRE-like1) led to a dramatic inhibition of the promoter responsiveness to peptones. Over expression of a dominant-negative mutant of CREB or of PKA produced a comparable and selective inhibitory effect on the activity of transfected promoter fragment containing the -350/-292 sequence. EMSA showed that CREB and fra2 transcription factors bound to CRE(PG) and CRE-like1 elements respectively, independently of peptone treatment. CONCLUSIONS/INTERPRETATION Our report identified cis- and trans-regulatory elements implicated in the transcriptional control of PG gene by nutrients in enteroendocrine cells. It highlights the role of a previously unsuspected CRE-like1 element, and emphasises the importance of CRE-related sequences in the regulation of PG gene transcription in the intestine.
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Affiliation(s)
- J-C Gevrey
- INSERM Unité 45, IFR 62, Faculté de Médecine RTH Laënnec, Lyon, France
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49
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Wang J, Cao Y, Steiner DF. Regulation of proglucagon transcription by activated transcription factor (ATF) 3 and a novel isoform, ATF3b, through the cAMP-response element/ATF site of the proglucagon gene promoter. J Biol Chem 2003; 278:32899-904. [PMID: 12815047 DOI: 10.1074/jbc.m305456200] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Glucagon, the second major glucose-regulated hormone in the control of glucose homeostasis, functions as a counter-regulator to insulin and is specifically produced by the pancreatic alpha cells. Its excessive biosynthesis and secretion is associated with diabetes mellitus. The expression of the proglucagon gene has been demonstrated to be regulated by a cAMP-dependent pathway through cAMP-response element-binding protein (CREB) and possibly other transcription factors bound to its cAMP-response element (CRE)/activated transcription factor (ATF) site. Elsewhere we have shown that ATF3, a member of the ATF/CREB subfamily of the basic leucine zipper domain proteins, is expressed predominantly in the alpha cells of the pancreatic islets. In our attempts to further dissect the role of ATF3 proteins in alpha cells, we have identified and characterized a novel alternatively spliced form, ATF3b, and have compared the specific binding ability of ATF3 and ATF3b on the CRE/ATF motif of the proglucagon promoter. Our findings indicate the existence of a novel mechanism by which the transcription of the proglucagon gene is regulated in response to cAMP signals, in addition to CREB and in relation to glucose fluctuations in pancreatic alpha cells.
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Affiliation(s)
- Jie Wang
- Department of Biochemistry and Molecular Biology, University of Chicago, Illinois 60637, USA
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50
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Cao X, Flock G, Choi C, Irwin DM, Drucker DJ. Aberrant regulation of human intestinal proglucagon gene expression in the NCI-H716 cell line. Endocrinology 2003; 144:2025-33. [PMID: 12697711 DOI: 10.1210/en.2002-0049] [Citation(s) in RCA: 29] [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
Despite interest in understanding glucagon-like peptide-1 (GLP-1) production, the factors important for GLP-1 biosynthesis remain poorly understood. We examined control of human proglucagon gene expression in NCI-H716 cells, a cell line that secretes GLP-1 in a regulated manner. Insulin, phorbol myristate acetate, or forskolin, known regulators of rodent proglucagon gene expression, had no effect, whereas sodium butyrate decreased levels of NCI-H716 proglucagon mRNA transcripts. The inhibitory effect of sodium butyrate was mimicked by trichostatin A but was not detected with sodium acetate or isobutyrate. The actions of butyrate were not diminished by the ERK1/2 inhibitor PD98059, p38 inhibitor SB203580, or soluble guanylate cyclase inhibitor LY83583 or following treatment of cells with KT5823, a selective inhibitor of cGMP-dependent protein kinase. NCI-H716 cells expressed multiple proglucagon gene transcription factors including isl-1, pax-6, pax-2, cdx-2/3, pax-4, hepatocyte nuclear factor (HNF)-3 alpha, HNF-3beta, HNF-3 gamma, and Nkx2.2. Nevertheless, the butyrate-dependent inhibition of proglucagon gene expression was not associated with coordinate changes in transcription factor expression and both the human and rat transfected proglucagon promoters were transcriptionally inactive in NCI-H716 cells. Hence, NCI-H716 cells may not be a physiologically optimal model for studies of human enteroendocrine proglucagon gene transcription.
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Affiliation(s)
- Xiemin Cao
- Banting and Best Diabetes Centre, Toronto General Hospital, University of Toronto, Toronto, Canada M5G 2C4
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