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Holter MM, Saikia M, Cummings BP. Alpha-cell paracrine signaling in the regulation of beta-cell insulin secretion. Front Endocrinol (Lausanne) 2022; 13:934775. [PMID: 35957816 PMCID: PMC9360487 DOI: 10.3389/fendo.2022.934775] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 06/28/2022] [Indexed: 01/14/2023] Open
Abstract
As an incretin hormone, glucagon-like peptide 1 (GLP-1) lowers blood glucose levels by enhancing glucose-stimulated insulin secretion from pancreatic beta-cells. Therapies targeting the GLP-1 receptor (GLP-1R) use the classical incretin model as a physiological framework in which GLP-1 secreted from enteroendocrine L-cells acts on the beta-cell GLP-1R. However, this model has come into question, as evidence demonstrating local, intra-islet GLP-1 production has advanced the competing hypothesis that the incretin activity of GLP-1 may reflect paracrine signaling of GLP-1 from alpha-cells on GLP-1Rs on beta-cells. Additionally, recent studies suggest that alpha-cell-derived glucagon can serve as an additional, albeit less potent, ligand for the beta-cell GLP-1R, thereby expanding the role of alpha-cells beyond that of a counterregulatory cell type. Efforts to understand the role of the alpha-cell in the regulation of islet function have revealed both transcriptional and functional heterogeneity within the alpha-cell population. Further analysis of this heterogeneity suggests that functionally distinct alpha-cell subpopulations display alterations in islet hormone profile. Thus, the role of the alpha-cell in glucose homeostasis has evolved in recent years, such that alpha-cell to beta-cell communication now presents a critical axis regulating the functional capacity of beta-cells. Herein, we describe and integrate recent advances in our understanding of the impact of alpha-cell paracrine signaling on insulin secretory dynamics and how this intra-islet crosstalk more broadly contributes to whole-body glucose regulation in health and under metabolic stress. Moreover, we explore how these conceptual changes in our understanding of intra-islet GLP-1 biology may impact our understanding of the mechanisms of incretin-based therapeutics.
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Affiliation(s)
- Marlena M. Holter
- Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, United States
- *Correspondence: Marlena M. Holter,
| | - Mridusmita Saikia
- Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, United States
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, United States
| | - Bethany P. Cummings
- School of Medicine, Department of Surgery, Center for Alimentary and Metabolic Sciences, University of California, Davis, Sacramento, CA, United States
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2
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Bethea M, Bozadjieva-Kramer N, Sandoval DA. Preproglucagon Products and Their Respective Roles Regulating Insulin Secretion. Endocrinology 2021; 162:6329397. [PMID: 34318874 PMCID: PMC8375443 DOI: 10.1210/endocr/bqab150] [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: 05/24/2021] [Indexed: 11/19/2022]
Abstract
Historically, intracellular function and metabolic adaptation within the α-cell has been understudied, with most of the attention being placed on the insulin-producing β-cells due to their role in the pathophysiology of type 2 diabetes mellitus. However, there is a growing interest in understanding the function of other endocrine cell types within the islet and their paracrine role in regulating insulin secretion. For example, there is greater appreciation for α-cell products and their contributions to overall glucose homeostasis. Several recent studies have addressed a paracrine role for α-cell-derived glucagon-like peptide-1 (GLP-1) in regulating glucose homeostasis and responses to metabolic stress. Further, other studies have demonstrated the ability of glucagon to impact insulin secretion by acting through the GLP-1 receptor. These studies challenge the central dogma surrounding α-cell biology describing glucagon's primary role in glucose counterregulation to one where glucagon is critical in regulating both hyper- and hypoglycemic responses. Herein, this review will update the current understanding of the role of glucagon and α-cell-derived GLP-1, placing emphasis on their roles in regulating glucose homeostasis, insulin secretion, and β-cell mass.
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Affiliation(s)
- Maigen Bethea
- Department of Pediatrics, Nutrition Section, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
- Division of Endocrinology, Metabolism, and Diabetes, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | | | - Darleen A Sandoval
- Department of Pediatrics, Nutrition Section, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
- Division of Endocrinology, Metabolism, and Diabetes, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
- Correspondence: Darleen A. Sandoval, PhD, University of Colorado Anschut, Division of Endocrinology, Metabolism, and Diabetes,12801 E 17th Ave. Research Complex 1 South 7th Floor, Aurora, CO 80045, USA. E-mail:
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3
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Zeigerer A, Sekar R, Kleinert M, Nason S, Habegger KM, Müller TD. Glucagon's Metabolic Action in Health and Disease. Compr Physiol 2021; 11:1759-1783. [PMID: 33792899 PMCID: PMC8513137 DOI: 10.1002/cphy.c200013] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Discovered almost simultaneously with insulin, glucagon is a pleiotropic hormone with metabolic action that goes far beyond its classical role to increase blood glucose. Albeit best known for its ability to directly act on the liver to increase de novo glucose production and to inhibit glycogen breakdown, glucagon lowers body weight by decreasing food intake and by increasing metabolic rate. Glucagon further promotes lipolysis and lipid oxidation and has positive chronotropic and inotropic effects in the heart. Interestingly, recent decades have witnessed a remarkable renaissance of glucagon's biology with the acknowledgment that glucagon has pharmacological value beyond its classical use as rescue medication to treat severe hypoglycemia. In this article, we summarize the multifaceted nature of glucagon with a special focus on its hepatic action and discuss the pharmacological potential of either agonizing or antagonizing the glucagon receptor for health and disease. © 2021 American Physiological Society. Compr Physiol 11:1759-1783, 2021.
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Affiliation(s)
- Anja Zeigerer
- Institute for Diabetes and Cancer, Helmholtz Center Munich, Neuherberg, Germany
- German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - Revathi Sekar
- Institute for Diabetes and Cancer, Helmholtz Center Munich, Neuherberg, Germany
- German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - Maximilian Kleinert
- German Center for Diabetes Research (DZD), Neuherberg, Germany
- Institute for Diabetes and Obesity, Helmholtz Center Munich, Neuherberg, Germany
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Shelly Nason
- Comprehensive Diabetes Center, Department of Medicine - Endocrinology, Diabetes & Metabolism, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Kirk M. Habegger
- Comprehensive Diabetes Center, Department of Medicine - Endocrinology, Diabetes & Metabolism, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Timo D. Müller
- German Center for Diabetes Research (DZD), Neuherberg, Germany
- Institute for Diabetes and Obesity, Helmholtz Center Munich, Neuherberg, Germany
- Department of Pharmacology, Experimental Therapy and Toxicology, Institute of Experimental and Clinical Pharmacology and Pharmacogenomics, Eberhard Karls University Hospitals and Clinics, Tübingen, Germany
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4
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Saikia M, Holter MM, Donahue LR, Lee IS, Zheng QC, Wise JL, Todero JE, Phuong DJ, Garibay D, Coch R, Sloop KW, Garcia-Ocana A, Danko CG, Cummings BP. GLP-1 receptor signaling increases PCSK1 and β cell features in human α cells. JCI Insight 2021; 6:141851. [PMID: 33554958 PMCID: PMC7934853 DOI: 10.1172/jci.insight.141851] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 12/29/2020] [Indexed: 02/06/2023] Open
Abstract
Glucagon-like peptide-1 (GLP-1) is an incretin hormone that potentiates glucose-stimulated insulin secretion. GLP-1 is classically produced by gut L cells; however, under certain circumstances α cells can express the prohormone convertase required for proglucagon processing to GLP-1, prohormone convertase 1/3 (PC1/3), and can produce GLP-1. However, the mechanisms through which this occurs are poorly defined. Understanding the mechanisms by which α cell PC1/3 expression can be activated may reveal new targets for diabetes treatment. Here, we demonstrate that the GLP-1 receptor (GLP-1R) agonist, liraglutide, increased α cell GLP-1 expression in a β cell GLP-1R-dependent manner. We demonstrate that this effect of liraglutide was translationally relevant in human islets through application of a new scRNA-seq technology, DART-Seq. We found that the effect of liraglutide to increase α cell PC1/3 mRNA expression occurred in a subcluster of α cells and was associated with increased expression of other β cell-like genes, which we confirmed by IHC. Finally, we found that the effect of liraglutide to increase bihormonal insulin+ glucagon+ cells was mediated by the β cell GLP-1R in mice. Together, our data validate a high-sensitivity method for scRNA-seq in human islets and identify a potentially novel GLP-1-mediated pathway regulating human α cell function.
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Affiliation(s)
- Mridusmita Saikia
- Department of Biomedical Sciences and
- Baker Institute for Animal Health, Cornell University College of Veterinary Medicine, Ithaca, New York, USA
| | | | | | | | | | | | | | | | | | - Reilly Coch
- Cayuga Medical Center, Ithaca, New York, USA
| | - Kyle W Sloop
- Diabetes and Complications, Lilly Research Laboratories, Lilly, Indianapolis, Indiana, USA
| | | | - Charles G Danko
- Department of Biomedical Sciences and
- Baker Institute for Animal Health, Cornell University College of Veterinary Medicine, Ithaca, New York, USA
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5
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Guo X, Li D, Song J, Yang Q, Wang M, Yang Y, Wang L, Hou X, Chen L, Li X. Mof regulates glucose level via altering different α-cell subset mass and intra-islet glucagon-like peptide-1, glucagon secretion. Metabolism 2020; 109:154290. [PMID: 32522488 DOI: 10.1016/j.metabol.2020.154290] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 06/02/2020] [Accepted: 06/05/2020] [Indexed: 12/11/2022]
Abstract
BACKGROUND Males absent on the first (Mof) is implicated in gene control of diverse biological processes, such as cell growth, differentiation, apoptosis and autophagy. However, the relationship between glucose regulation and Mof-mediated transcription events remains unexplored. We aimed to unravel the role of Mof in glucose regulation by using global and pancreatic α-cell-specific Mof-deficient mice in vivo and α-TC1-6 cell line in vitro. METHODS We used tamoxifen-induced temporal Mof-deficient mice first to show Mof regulate glucose homeostasis, islet cell proportions and hormone secretion. Then we used α-cell-specific Mof-deficient mice to clarify how α-cell subsets and β-cell mass were regulated and corresponding hormone level alterations. Ultimately, we used small interfering RNA (siRNA) to knockdown Mof in α-TC1-6 and unravel the mechanism regulating α-cell mass and glucagon secretion. RESULTS Mof was mainly expressed in α-cells. Global Mof deficiency led to lower glucose levels, attributed by decreased α/β-cell ratio and glucagon secretion. α-cell-specific Mof-deficient mice exhibited similar alterations, with more reduced prohormone convertase 2 (PC2)-positive α-cell mass, responsible for less glucagon, and enhanced prohormone convertase 1 (PC1/3)-positive α-cell mass, leading to more glucagon-like peptide-1 (GLP-1) secretion, thus increased β-cell mass and insulin secretion. In vitro, increased DNA damage, dysregulated autophagy, enhanced apoptosis and altered cell fate factors expressions upon Mof knockdown were observed. Genes and pathways linked to impaired glucagon secretion were uncovered through transcriptome sequencing. CONCLUSION Mof is a potential interventional target for glucose regulation, from the aspects of both α-cell subset mass and glucagon, intra-islet GLP-1 secretion. Upon Mof deficiency, Up-regulated PC1/3 but down-regulated PC2-positive α-cell mass, leads to more GLP-1 and insulin but less glucagon secretion, and contributed to lower glucose level.
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Affiliation(s)
- Xinghong Guo
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao 266237, Shandong, China; Department of Endocrinology, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan 250012, Shandong, China
| | - Danyang Li
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao 266237, Shandong, China; Department of Rehabilitation, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan 250012, Shandong, China
| | - Jia Song
- Department of Endocrinology, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan 250012, Shandong, China
| | - Qibing Yang
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao 266237, Shandong, China
| | - Meng Wang
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao 266237, Shandong, China
| | - Yang Yang
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao 266237, Shandong, China
| | - Lingshu Wang
- Institute of Endocrine and Metabolic Diseases of Shandong University, Jinan 250012, Shandong, China; Key Laboratory of Endocrine and Metabolic Diseases, Shandong Province Medicine & Health, Jinan 250012, Shandong, China
| | - Xinguo Hou
- Department of Endocrinology, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan 250012, Shandong, China
| | - Li Chen
- Department of Endocrinology, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan 250012, Shandong, China; Institute of Endocrine and Metabolic Diseases of Shandong University, Jinan 250012, Shandong, China; Key Laboratory of Endocrine and Metabolic Diseases, Shandong Province Medicine & Health, Jinan 250012, Shandong, China.
| | - Xiangzhi Li
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Qingdao 266237, Shandong, China.
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6
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Kim S, Whitener RL, Peiris H, Gu X, Chang CA, Lam JY, Camunas-Soler J, Park I, Bevacqua RJ, Tellez K, Quake SR, Lakey JRT, Bottino R, Ross PJ, Kim SK. Molecular and genetic regulation of pig pancreatic islet cell development. Development 2020; 147:dev186213. [PMID: 32108026 PMCID: PMC7132804 DOI: 10.1242/dev.186213] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 02/20/2020] [Indexed: 12/12/2022]
Abstract
Reliance on rodents for understanding pancreatic genetics, development and islet function could limit progress in developing interventions for human diseases such as diabetes mellitus. Similarities of pancreas morphology and function suggest that porcine and human pancreas developmental biology may have useful homologies. However, little is known about pig pancreas development. To fill this knowledge gap, we investigated fetal and neonatal pig pancreas at multiple, crucial developmental stages using modern experimental approaches. Purification of islet β-, α- and δ-cells followed by transcriptome analysis (RNA-seq) and immunohistology identified cell- and stage-specific regulation, and revealed that pig and human islet cells share characteristic features that are not observed in mice. Morphometric analysis also revealed endocrine cell allocation and architectural similarities between pig and human islets. Our analysis unveiled scores of signaling pathways linked to native islet β-cell functional maturation, including evidence of fetal α-cell GLP-1 production and signaling to β-cells. Thus, the findings and resources detailed here show how pig pancreatic islet studies complement other systems for understanding the developmental programs that generate functional islet cells, and that are relevant to human pancreatic diseases.
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Affiliation(s)
- Seokho Kim
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Robert L Whitener
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Heshan Peiris
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Xueying Gu
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Charles A Chang
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Jonathan Y Lam
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Joan Camunas-Soler
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Insung Park
- Department of Animal Science, University of California Davis, Davis, CA 95616, USA
| | - Romina J Bevacqua
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Krissie Tellez
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Stephen R Quake
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
- Chan Zuckerberg Biohub, San Francisco, CA 94518, USA
| | - Jonathan R T Lakey
- Department of Surgery, University of California at Irvine, Irvine, CA 92868, USA
| | - Rita Bottino
- Institute of Cellular Therapeutics, Allegheny Health Network, Pittsburgh, PA 15212, USA
| | - Pablo J Ross
- Department of Animal Science, University of California Davis, Davis, CA 95616, USA
| | - Seung K Kim
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
- Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
- Stanford Diabetes Research Center, Stanford University School of Medicine, Stanford, CA 94305, USA
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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: 862] [Impact Index Per Article: 172.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 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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Holst JJ, Albrechtsen NJW, Rosenkilde MM, Deacon CF. Physiology of the Incretin Hormones,
GIP
and
GLP
‐1—Regulation of Release and Posttranslational Modifications. Compr Physiol 2019; 9:1339-1381. [DOI: 10.1002/cphy.c180013] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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10
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Abstract
PURPOSE OF REVIEW To discuss the current understanding of "β cell identity" and factors underlying altered identity of pancreatic β cells in diabetes, especially in humans. RECENT FINDINGS Altered identity of β cells due to dedifferentiation and/or transdifferentiation has been proposed as a mechanism of loss of β cells in diabetes. In dedifferentiation, β cells do not undergo apoptosis; rather, they lose their identity and function. Dedifferentiation is well characterized by the decrease in expression of key β cell markers such as genes encoding major transcription factors, e.g., MafA, NeuroD1, Nkx6.1, and Foxo1, and an increase in atypical or "disallowed" genes for β cells such as lactate dehydrogenase, monocarboxylate transporter MCT1, or progenitor cell genes (Neurog3, Pax4, or Sox9). Moreover, altered identity of mature β cells in diabetes also involves transdifferentiation of β cells into other islet hormone producing cells. For example, overexpression of α cell specific transcription factor Arx or ablation of Pdx1 resulted in an increase of α cell numbers and a decrease in β cell numbers in rodents. The frequency of α-β double-positive cells was also prominent in human subjects with T2D. These altered identities of β cells likely serve as a compensatory response to enhance function/expand cell numbers and may also camouflage/protect cells from ongoing stress. However, it is equally likely that this may be a reflection of new cell formation as a frank regenerative response to ongoing tissue injury. Physiologically, all these responses are complementary. In diabetes, (1) endocrine identity recapitulates the less mature/less-differentiated fetal/neonatal cell type, possibly representing an adaptive mechanism; (2) residual β cells may be altered in their subtype proportions or other molecular features; (3) in humans, "altered identity" is a preferable term to dedifferentiation as their cellular fate (differentiated cells losing identity or progenitors becoming more differentiated) is unclear as yet.
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Affiliation(s)
- Abu Saleh Md Moin
- Diabetes Research Center, Qatar Biomedical Research Institute, Hamad Bin Khalifa University, Qatar Foundation, PO Box 34110 Doha, Qatar
| | - Alexandra E. Butler
- Diabetes Research Center, Qatar Biomedical Research Institute, Hamad Bin Khalifa University, Qatar Foundation, PO Box 34110 Doha, Qatar
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11
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Jacobson EF, Tzanakakis ES. Human pluripotent stem cell differentiation to functional pancreatic cells for diabetes therapies: Innovations, challenges and future directions. J Biol Eng 2017; 11:21. [PMID: 28680477 PMCID: PMC5494890 DOI: 10.1186/s13036-017-0066-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Accepted: 06/02/2017] [Indexed: 12/18/2022] Open
Abstract
Recent advances in the expansion and directed pancreatogenic differentiation of human pluripotent stem cells (hPSCs) have intensified efforts to generate functional pancreatic islet cells, especially insulin-secreting β-cells, for cell therapies against diabetes. However, the consistent generation of glucose-responsive insulin-releasing cells remains challenging. In this article, we first present basic concepts of pancreatic organogenesis, which frequently serves as a basis for engineering differentiation regimens. Next, past and current efforts are critically discussed for the conversion of hPSCs along pancreatic cell lineages, including endocrine β-cells and α-cells, as well as exocrine cells with emphasis placed on the later stages of commitment. Finally, major challenges and future directions are examined, such as the identification of factors for in vivo maturation, large-scale culture and post processing systems, cell loss during differentiation, culture economics, efficiency, and efficacy and exosomes and miRNAs in pancreatic differentiation.
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Affiliation(s)
- Elena F Jacobson
- Department of Chemical and Biological Engineering, Tufts University, 4 Colby St., Room 276A, Medford, MA 02155 USA
| | - Emmanuel S Tzanakakis
- Department of Chemical and Biological Engineering, Tufts University, 4 Colby St., Room 276A, Medford, MA 02155 USA.,Tufts Clinical and Translational Science Institute, Tufts Medical Center, Boston, MA 02111 USA
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12
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Prasadan K, Shiota C, Xiangwei X, Ricks D, Fusco J, Gittes G. A synopsis of factors regulating beta cell development and beta cell mass. Cell Mol Life Sci 2016; 73:3623-37. [PMID: 27105622 PMCID: PMC5002366 DOI: 10.1007/s00018-016-2231-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Revised: 03/24/2016] [Accepted: 04/14/2016] [Indexed: 12/29/2022]
Abstract
The insulin-secreting beta cells in the endocrine pancreas regulate blood glucose levels, and loss of functional beta cells leads to insulin deficiency, hyperglycemia (high blood glucose) and diabetes mellitus. Current treatment strategies for type-1 (autoimmune) diabetes are islet transplantation, which has significant risks and limitations, or normalization of blood glucose with insulin injections, which is clearly not ideal. The type-1 patients can lack insulin counter-regulatory mechanism; therefore, hypoglycemia is a potential risk. Hence, a cell-based therapy offers a better alternative for the treatment of diabetes. Past research was focused on attempting to generate replacement beta cells from stem cells; however, recently there has been an increasing interest in identifying mechanisms that will lead to the conversion of pre-existing differentiated endocrine cells into beta cells. The goal of this review is to provide an overview of several of the key factors that regulate new beta cell formation (neogenesis) and beta cell proliferation.
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Affiliation(s)
- Krishna Prasadan
- Rangos Research Center, Children's Hospital of University of Pittsburgh, 4401 Penn Avenue, Pittsburgh, PA, 15224, USA
| | - Chiyo Shiota
- Rangos Research Center, Children's Hospital of University of Pittsburgh, 4401 Penn Avenue, Pittsburgh, PA, 15224, USA
| | - Xiao Xiangwei
- Rangos Research Center, Children's Hospital of University of Pittsburgh, 4401 Penn Avenue, Pittsburgh, PA, 15224, USA
| | - David Ricks
- Rangos Research Center, Children's Hospital of University of Pittsburgh, 4401 Penn Avenue, Pittsburgh, PA, 15224, USA
| | - Joseph Fusco
- Rangos Research Center, Children's Hospital of University of Pittsburgh, 4401 Penn Avenue, Pittsburgh, PA, 15224, USA
| | - George Gittes
- Rangos Research Center, Children's Hospital of University of Pittsburgh, 4401 Penn Avenue, Pittsburgh, PA, 15224, USA.
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13
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Abstract
The alpha cells that co-occupy the islets in association with beta cells have been long recognized as the source of glucagon, a hyperglycemia-producing and diabetogenic hormone. Although the mechanisms that control the functions of alpha cells, glucagon secretion, and the role of glucagon in diabetes have remained somewhat enigmatic over the fifty years since their discovery, seminal findings during the past few years have moved alpha cells into the spotlight of scientific discovery. These findings obtained largely from studies in mice are: Alpha cells have the capacity to trans-differentiate into insulin-producing beta cells. Alpha cells contain a GLP-1 generating system that produces GLP-1 locally for paracrine actions within the islets that likely promotes beta cell growth and survival and maintains beta cell mass. Impairment of glucagon signaling both prevents the occurrence of diabetes in conditions of the near absence of insulin and expands alpha cell mass. Alpha cells appear to serve as helper cells or guardians of beta cells to ensure their health and well-being. Of potential relevance to the possibility of promoting the transformation of alpha to beta cells is the observation that impairment of glucagon signaling leads to a marked increase in alpha cell mass in the islets. Such alpha cell hyperplasia provides an increased supply of alpha cells for their transdifferentiation into new beta cells. In this review we discuss these recent discoveries from the perspective of their potential relevance to the treatment of diabetes.
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Affiliation(s)
- Violeta Stanojevic
- Laboratory of Molecular Endocrinology, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA
| | - Joel F Habener
- Laboratory of Molecular Endocrinology, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA.
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14
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Plasma amylin concentration in suckling goat neonates and its relationship with C-reactive protein, selected biochemical and hormonal indicators. ACTA VET BRNO 2015. [DOI: 10.2754/avb201584030237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Amylin is a recently discovered neuropeptide hormone that belongs to the calcitonin gene-related peptide family. It is co-secreted with insulin in response to feed intake. In goat kids, neonatal mortality and morbidity seems to be relatively higher than in other farm species. This high mortality and morbidity in goat kids may be associated with underdeveloped metabolism and immune system during the first week of life. The main objectives of this study were to determine amylin concentration and its relationship with some hormones, biochemical indicators and with a general inflammatory marker, CRP (C-reactive protein) in goat neonates. Blood samples were collected from 30 Saanen goat neonates at 20–35 days of age. Plasma amylin and other hormone concentrations were measured by ELISA, whereas serum biochemical indices were analysed by spectrophotometry. The mean values of plasma amylin concentrations were 9.07 ± 0.25 pmol/l. Plasma amylin concentrations were positively correlated with plasma non-esterified fatty acids, CRP, prolactin, cortisol, insulin; however, a negative correlation was determined between plasma amylin and serum triglyceride concentrations. The current study suggests that amylin contents are strongly associated with circulating concentrations of some hormones and with those of CRP in Saanen goat kids.
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15
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Sandoval DA, D'Alessio DA. Physiology of proglucagon peptides: role of glucagon and GLP-1 in health and disease. Physiol Rev 2015; 95:513-48. [PMID: 25834231 DOI: 10.1152/physrev.00013.2014] [Citation(s) in RCA: 286] [Impact Index Per Article: 31.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The preproglucagon gene (Gcg) is expressed by specific enteroendocrine cells (L-cells) of the intestinal mucosa, pancreatic islet α-cells, and a discrete set of neurons within the nucleus of the solitary tract. Gcg encodes multiple peptides including glucagon, glucagon-like peptide-1, glucagon-like peptide-2, oxyntomodulin, and glicentin. Of these, glucagon and GLP-1 have received the most attention because of important roles in glucose metabolism, involvement in diabetes and other disorders, and application to therapeutics. The generally accepted model is that GLP-1 improves glucose homeostasis indirectly via stimulation of nutrient-induced insulin release and by reducing glucagon secretion. Yet the body of literature surrounding GLP-1 physiology reveals an incompletely understood and complex system that includes peripheral and central GLP-1 actions to regulate energy and glucose homeostasis. On the other hand, glucagon is established principally as a counterregulatory hormone, increasing in response to physiological challenges that threaten adequate blood glucose levels and driving glucose production to restore euglycemia. However, there also exists a potential role for glucagon in regulating energy expenditure that has recently been suggested in pharmacological studies. It is also becoming apparent that there is cross-talk between the proglucagon derived-peptides, e.g., GLP-1 inhibits glucagon secretion, and some additive or synergistic pharmacological interaction between GLP-1 and glucagon, e.g., dual glucagon/GLP-1 agonists cause more weight loss than single agonists. In this review, we discuss the physiological functions of both glucagon and GLP-1 by comparing and contrasting how these peptides function, variably in concert and opposition, to regulate glucose and energy homeostasis.
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Affiliation(s)
- Darleen A Sandoval
- Division of Endocrinology and Metabolism, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - David A D'Alessio
- Division of Endocrinology and Metabolism, University of Cincinnati College of Medicine, Cincinnati, Ohio
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16
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Vázquez P, Robles AM, de Pablo F, Hernández-Sánchez C. Non-neural tyrosine hydroxylase, via modulation of endocrine pancreatic precursors, is required for normal development of beta cells in the mouse pancreas. Diabetologia 2014; 57:2339-47. [PMID: 25082160 PMCID: PMC4181516 DOI: 10.1007/s00125-014-3341-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Accepted: 07/01/2014] [Indexed: 11/07/2022]
Abstract
AIMS/HYPOTHESIS Apart from transcription factors, little is known about the molecules that modulate the proliferation and differentiation of pancreatic endocrine cells. The early expression of tyrosine hydroxylase (TH) in a subset of glucagon(+) cells led us to investigate whether catecholamines have a role in beta cell development. METHODS We studied the immunohistochemical characteristics of TH-expressing cells in wild-type (Th (+/+) ) mice during early pancreas development, and analysed the endocrine pancreas phenotype of TH-deficient (Th (-/-) ) mice. We also studied the effect of dopamine addition and TH-inhibition on insulin-producing cells in explant cultures. RESULTS In the mouse pancreas at embryonic day (E)12.5-E13.5, the ∼10% of early glucagon(+) cells that co-expressed TH rarely proliferated and did not express the precursor marker neurogenin 3 at E13.5. The number of insulin(+) cells in the Th (-/-) embryonic pancreas was decreased as compared with wild-type embryos at E13.5. While no changes in pancreatic and duodenal homeobox 1 (PDX1)(+)-progenitor cell number were observed between groups at E12.5, the number of neurogenin 3 and NK2 homeobox 2 (NKX2.2)-expressing cells was reduced in Th (-/-) embryonic pancreas, an effect that occurred in parallel with increased expression of the transcriptional repressor Hes1. The potential role of dopamine as a pro-beta cell stimulus was tested by treating pancreas explants with this catecholamine, which resulted in an increase in total insulin content and insulin(+) cells relative to control explants. CONCLUSIONS/INTERPRETATION A non-neural catecholaminergic pathway appears to modulate the pancreatic endocrine precursor and insulin producing cell neogenesis. This finding may have important implications for approaches seeking to promote the generation of beta cells to treat diabetes.
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Affiliation(s)
- Patricia Vázquez
- 3D (Development, Differentiation, Degeneration) Lab, Department of Cellular and Molecular Medicine, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM) (ISCIII), Ministerio de Economía y Competitividad, Spain, http://www.ciberdem.org/
| | - Ana M. Robles
- 3D (Development, Differentiation, Degeneration) Lab, Department of Cellular and Molecular Medicine, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Flora de Pablo
- 3D (Development, Differentiation, Degeneration) Lab, Department of Cellular and Molecular Medicine, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM) (ISCIII), Ministerio de Economía y Competitividad, Spain, http://www.ciberdem.org/
| | - Catalina Hernández-Sánchez
- 3D (Development, Differentiation, Degeneration) Lab, Department of Cellular and Molecular Medicine, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM) (ISCIII), Ministerio de Economía y Competitividad, Spain, http://www.ciberdem.org/
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17
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Liu L, Omar B, Marchetti P, Ahrén B. Dipeptidyl peptidase-4 (DPP-4): Localization and activity in human and rodent islets. Biochem Biophys Res Commun 2014; 453:398-404. [PMID: 25268763 DOI: 10.1016/j.bbrc.2014.09.096] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2014] [Accepted: 09/22/2014] [Indexed: 01/26/2023]
Abstract
Dipeptidyl peptidase 4 (DPP-4) was recently found to be expressed in human and mouse islets with different expression patterns. However, whether species-dependent expression pattern is a generalized phenomenon and whether islet DPP-4 activity is regulated are not known. This study was conducted to investigate DPP-4 localization in several different species, and to examine the impact of glucose, incretin hormones, and insulin on islet DPP-4 activity. It was shown by immuofluorescent staining that there were two distinct species-specific expression patterns of islet DPP-4. The enzyme was expressed exclusively in α-cells in human and pig islets, but primarily in β-cells in mouse and rat islets. INS-1 832/13 cells also expressed DPP-4, and inhibition of DPP-4 enhanced insulin secretion in the presence of glucagon-like peptide-1 (GLP-1) in the cells. DPP-4 activity was remarkably robust when cultured with high glucose, incretin hormones, and insulin in mouse and human islets as well as INS-1 832/13 cells and islet DPP-4 activity and expression pattern was not altered in double incretin receptor knockout mice, compared to wild type mice. We conclude that islet DPP-4 is species-specifically expressed in α-cell and β-cell dominant patterns in several species and both patterns remained robust in enzyme activity during short-term metabolic challenge.
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Affiliation(s)
- Liehua Liu
- The First Affiliated Hospital of Sun Yat-sen University, Guangzhou 510080, China; Department of Clinical Sciences, Lund, Medicine, Lund University, SE22184 Lund, Sweden
| | - Bilal Omar
- Department of Clinical Sciences, Lund, Medicine, Lund University, SE22184 Lund, Sweden
| | - Piero Marchetti
- Department of Clinical and Experimental Medicine, Islet Cell Laboratory, University of Pisa, 56126 Pisa, Italy
| | - Bo Ahrén
- Department of Clinical Sciences, Lund, Medicine, Lund University, SE22184 Lund, Sweden.
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18
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Malouf GG, Job S, Paradis V, Fabre M, Brugières L, Saintigny P, Vescovo L, Belghiti J, Branchereau S, Faivre S, de Reyniès A, Raymond E. Transcriptional profiling of pure fibrolamellar hepatocellular carcinoma reveals an endocrine signature. Hepatology 2014; 59:2228-37. [PMID: 24443104 DOI: 10.1002/hep.27018] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Accepted: 01/14/2014] [Indexed: 12/16/2022]
Abstract
UNLABELLED Fibrolamellar hepatocellular carcinoma (FLC) is a rare subtype of liver cancer occurring mostly in children and young adults. We have shown that FLC comprises two separate entities: pure (p-FLC) and mixed-FLC (m-FLC), differing in clinical presentation and course. We show that p-FLCs have a distinct gene expression signature different from that of m-FLCs, which have a signature similar to that of classical hepatocellular carcinomas. We found p-FLC profiles to be unique among 263 profiles related to diverse tumoral and nontumoral liver samples. We identified two distinct molecular subgroups of p-FLCs with different outcomes. Pathway analysis of p-FLCs revealed ERBB2 overexpression and an up-regulation of glycolysis, possibly leading to compensatory mitochondrial hyperplasia and oncocytic differentiation. Four of the sixteen genes most significantly overexpressed in p-FLCs were neuroendocrine genes: prohormone convertase 1 (PCSK1); neurotensin; delta/notch-like EGF repeat containing; and calcitonin. PCSK1 overexpression was validated by immunohistochemistry, yielding specific, diffuse staining of the protein throughout the cytoplasm, possibly corresponding to a functional form of this convertase. CONCLUSION p-FLCs have a unique transcriptomic signature characterized by the strong expression of specific neuroendocrine genes, suggesting that these tumors may have a cellular origin different from that of HCC. Our data have implications for the use of genomic profiling for diagnosis and selection of targeted therapies in patients with p-FLC.
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Affiliation(s)
- Gabriel G Malouf
- Department of Medical Oncology, Beaujon University Hospital and INSERM U728, Clichy, France
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19
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van der Meulen T, Huising MO. Maturation of stem cell-derived beta-cells guided by the expression of urocortin 3. Rev Diabet Stud 2014; 11:115-32. [PMID: 25148370 DOI: 10.1900/rds.2014.11.115] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Type 1 diabetes (T1D) is a devastating disease precipitated by an autoimmune response directed at the insulin-producing beta-cells of the pancreas for which no cure exists. Stem cell-derived beta-cells show great promise for a cure as they have the potential to supply unlimited numbers of cells that could be derived from a patient's own cells, thus eliminating the need for immunosuppression. Current in vitro protocols for the differentiation of stem cell-derived beta-cells can successfully generate pancreatic endoderm cells. In diabetic rodents, such cells can differentiate further along the beta-cell lineage until they are eventually capable of restoring normoglycemia. While these observations demonstrate that stem cell-derived pancreatic endoderm has the potential to differentiate into mature, glucose-responsive beta-cells, the signals that direct differentiation and maturation from pancreatic endoderm onwards remain poorly understood. In this review, we analyze the sequence of events that culminates in the formation of beta-cells during embryonic development. and summarize how current protocols to generate beta-cells have sought to capitalize on this ontogenic template. We place particular emphasis on the current challenges and opportunities which occur in the later stages of beta-cell differentiation and maturation of transplantable stem cell-derived beta-cells. Another focus is on the question how the use of recently identified maturation markers such as urocortin 3 can be instrumental in guiding these efforts.
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Affiliation(s)
- Talitha van der Meulen
- The Salk Institute for Biological Studies, Clayton Laboratories for Peptide Biology, 10010 N. Torrey Pines Road, La Jolla, CA 92037, USA
| | - Mark O Huising
- The Salk Institute for Biological Studies, Clayton Laboratories for Peptide Biology, 10010 N. Torrey Pines Road, La Jolla, CA 92037, USA
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20
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Marchetti P, Lupi R, Bugliani M, Kirkpatrick CL, Sebastiani G, Grieco FA, Del Guerra S, D'Aleo V, Piro S, Marselli L, Boggi U, Filipponi F, Tinti L, Salvini L, Wollheim CB, Purrello F, Dotta F. A local glucagon-like peptide 1 (GLP-1) system in human pancreatic islets. Diabetologia 2012; 55:3262-72. [PMID: 22965295 DOI: 10.1007/s00125-012-2716-9] [Citation(s) in RCA: 187] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Accepted: 08/08/2012] [Indexed: 12/25/2022]
Abstract
AIMS/HYPOTHESIS Glucagon-like peptide 1 (GLP-1) is a major incretin, mainly produced by the intestinal L cells, with beneficial actions on pancreatic beta cells. However, while in vivo only very small amounts of GLP-1 reach the pancreas in bioactive form, some observations indicate that GLP-1 may also be produced in the islets. We performed comprehensive morphological, functional and molecular studies to evaluate the presence and various features of a local GLP-1 system in human pancreatic islet cells, including those from type 2 diabetic patients. METHODS The presence of insulin, glucagon, GLP-1, proconvertase (PC) 1/3 and PC2 was determined in human pancreas by immunohistochemistry with confocal microscopy. Islets were isolated from non-diabetic and type 2 diabetic donors. GLP-1 protein abundance was evaluated by immunoblotting and matrix-assisted laser desorption-ionisation-time of flight (MALDI-TOF) mass spectrometry. Single alpha and beta cell suspensions were obtained by enzymatic dissociation and FACS sorting. Glucagon and GLP-1 release were measured in response to nutrients. RESULTS Confocal microscopy showed the presence of GLP-1-like and PC1/3 immunoreactivity in subsets of alpha cells, whereas GLP-1 was not observed in beta cells. The presence of GLP-1 in isolated islets was confirmed by immunoblotting, followed by mass spectrometry. Isolated islets and alpha (but not beta) cell fractions released GLP-1, which was regulated by glucose and arginine. PC1/3 (also known as PCSK1) gene expression was shown in alpha cells. GLP-1 release was significantly higher from type 2 diabetic than from non-diabetic isolated islets. CONCLUSIONS/INTERPRETATION We have shown the presence of a functionally competent GLP-1 system in human pancreatic islets, which resides in alpha cells and might be modulated by type 2 diabetes.
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Affiliation(s)
- P Marchetti
- Department of Endocrinology and Metabolism, University of Pisa, Via Paradisa 2, Pisa, Italy.
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21
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Grigoryan M, Kedees MH, Guz Y, Teitelman G. Phenotype of entero-endocrine L cells becomes restricted during development. Dev Dyn 2012; 241:1986-92. [PMID: 23027401 DOI: 10.1002/dvdy.23875] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/18/2012] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Glucagon-like peptide (GLP)-1 and glucose-dependent insulinotropic polypeptide (GIP) are hormones secreted by L and K cells, respectively, and by LK cells. To characterize L and K cells during development, we examined ileum from embryonic (e)- 12 to e-17. RESULTS GLP-1 cells were first seen at e-15 and their number increased at e-17. At e-17, most GLP-1 cells co-expressed GIP. The transcription factors Pax6 and Pdx-1 are required for GIP expression, while Pax6 activates the expression of GLP-1. At e-17, the mucosa has GIP+ Pax6+, GIP+ Pdx-1+, GLP-1+ Pax6+, and GLP-1+ Pdx-1+ cells. Unlike ileal L cells of postnatal and adult mice, a subset of ileal L cells of e-17 embryos co-expressed GLP-1 and glucagon (Glu). Glu-positive cells contain proprotein-convertase 2 (PC2) and PC3/1, the enzymes responsible for Glu and GLP-1 synthesis, respectively. CONCLUSIONS Our findings indicate that most GLP-1+ cells of ileum of e-17 embryos co-express GIP and, therefore, are LK cells. In addition, a subset of GLP-1+ cells of embryos but not of neonates co-express glucagon, indicating that the expression of Glu in GLP-1+ cells disappears after birth.
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Affiliation(s)
- Marine Grigoryan
- Department of Cell Biology, SUNY-Downstate Medical Center, Brooklyn, New York 11203, USA
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22
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Villasenor A, Cleaver O. Crosstalk between the developing pancreas and its blood vessels: an evolving dialog. Semin Cell Dev Biol 2012; 23:685-92. [PMID: 22728668 DOI: 10.1016/j.semcdb.2012.06.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2012] [Accepted: 06/13/2012] [Indexed: 12/25/2022]
Abstract
Growth and development of embryonic organs goes hand in hand with development of the vascular system. Blood vessels have been known for centuries to supply nutrients and oxygen to all cell types in an organism, however, they have more recently been shown to provide specific cues required for the formation and functionality of a number of tissues. Here, we review the role of blood vessels during pancreas formation, from early specification of the initial pancreatic bud, to its growth and maturation. The overarching theme that emerges from the many studies carried out in the past decade is that the vasculature likely plays diverse and changing roles during pancreas organogenesis. Blood vessels are required for endocrine specification at the onset of pancreatic budding, while only a few days later, blood vessels suppress pancreatic branching and exocrine differentiation. In this review, we summarize our understanding to date about the crosstalk between the pancreas and its vasculature, and we provide a perspective on the promises and challenges of the field.
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Affiliation(s)
- Alethia Villasenor
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94158, USA
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23
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Abstract
This review considers the role of α-cells in β-cell generation and regeneration. We present recent evidence obtained from lineage-tracing studies showing that α-cells can serve as progenitors of β-cells and present a hypothetical model how injured β-cells might activate α-cells in adult islets to promote β-cell regeneration. β-cells appear to arise by way of their trans-differentiation from undifferentiated α progenitor cells, pro-α-cells, both during embryonic development of the islets and in the adult pancreas in response to β-cell injuries. Plasticity of α-cells is endowed by the expression of the gene encoding proglucagon, a prohormone that can give rise to glucagon and glucagon-like peptides (GLPs). The production of glucagon from proglucagon is characteristic of fully-differentiated α-cells whereas GLP-1 is a product of undifferentiated α-cells. GLP-1, a cell growth and survival factor, is proposed to promote the expansion of neurogenin3-expressing, undifferentiated pro-α-cells during development. β-cells arise from pro-α-cells by a change in the relative amounts of the transcription factors Arx and Pax4, master regulators of the α- and β-cell lineages, respectively. A paracrine/autocrine model is proposed whereby injuries of β-cells in adult islets induce the production and release of factors, such as stromal cell-derived factor-1, that cause the de-differentiation of adjacent α-cells into pro-α-cells. Pro-α-cells produce GLP-1 and its receptor that renders them competent to trans-differentiate into β-cells. The trans-differentiation of pro-α-cells into β-cells provides a potentially exploitable mechanism for the regeneration of β-cells in individuals with type 1 diabetes.
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Affiliation(s)
- Joel F Habener
- Laboratory of Molecular Endocrinology, Massachusetts General Hospital, Boston, MA, USA.
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24
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Kelly OG, Chan MY, Martinson LA, Kadoya K, Ostertag TM, Ross KG, Richardson M, Carpenter MK, D'Amour KA, Kroon E, Moorman M, Baetge EE, Bang AG. Cell-surface markers for the isolation of pancreatic cell types derived from human embryonic stem cells. Nat Biotechnol 2011; 29:750-6. [PMID: 21804561 DOI: 10.1038/nbt.1931] [Citation(s) in RCA: 242] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Accepted: 07/05/2011] [Indexed: 12/19/2022]
Abstract
Using a flow cytometry-based screen of commercial antibodies, we have identified cell-surface markers for the separation of pancreatic cell types derived from human embryonic stem (hES) cells. We show enrichment of pancreatic endoderm cells using CD142 and of endocrine cells using CD200 and CD318. After transplantation into mice, enriched pancreatic endoderm cells give rise to all the pancreatic lineages, including functional insulin-producing cells, demonstrating that they are pancreatic progenitors. In contrast, implanted, enriched polyhormonal endocrine cells principally give rise to glucagon cells. These antibodies will aid investigations that use pancreatic cells generated from pluripotent stem cells to study diabetes and pancreas biology.
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Affiliation(s)
- Olivia G Kelly
- ViaCyte, Inc. (formerly Novocell, Inc.), San Diego, California, USA.
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25
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Hansen AMK, Bödvarsdottir TB, Nordestgaard DNE, Heller RS, Gotfredsen CF, Maedler K, Fels JJ, Holst JJ, Karlsen AE. Upregulation of alpha cell glucagon-like peptide 1 (GLP-1) in Psammomys obesus--an adaptive response to hyperglycaemia? Diabetologia 2011; 54:1379-87. [PMID: 21347622 DOI: 10.1007/s00125-011-2080-1] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2010] [Accepted: 12/21/2010] [Indexed: 12/31/2022]
Abstract
AIMS/HYPOTHESIS The hormone glucagon-like peptide 1 (GLP-1) is released in response to a meal from the intestinal L-cells, where it is processed from proglucagon by the proconvertase (PC)1/3. In contrast, in the adult islets proglucagon is processed to glucagon by the PC2 enzyme. The aim of the study was to evaluate if, during the development of diabetes, alpha cells produce GLP-1 that, in turn, might trigger beta cell growth. METHODS Beta cell mass, GLP-1 and insulin levels were measured in the gerbil Psammomys obesus (P. obesus), a rodent model of nutritionally induced diabetes. Furthermore, the presence of biologically active forms of GLP-1 and PC1/3 in alpha cells was demonstrated by immunofluorescence, and the release of GLP-1 from isolated P. obesus, mouse and human islets was investigated. RESULTS During the development of diabetes in P. obesus, a significant increase in GLP-1 was detected in the portal vein (9.8 ± 1.5 vs 4.3 ± 0.7 pmol/l, p < 0.05), and in pancreas extracts (11.4 ± 2.2 vs 5.1 ± 1.3 pmol/g tissue, p < 0.05). Freshly isolated islets from hyperglycaemic animals released more GLP-1 following 24 h culture than islets from control animals (28.2 ± 4.4 pmol/l vs 5.8 ± 2.4, p < 0.01). GLP-1 release was increased from healthy P. obesus islets following culture in high glucose for 6 days (91 ± 9.1 pmol/l vs 28.8 ± 6.6, p < 0.01). High levels of GLP-1 were also found to be released from human islets. PC1/3 colocalised weakly with alpha cells. CONCLUSIONS/INTERPRETATION GLP-1 release from alpha cells is upregulated in P. obesus during the development of diabetes. A similar response is seen in islets exposed to high glucose, which supports the hypothesis that GLP-1 released from alpha cells promotes an increase in beta cell mass and function during metabolic challenge such as diabetes.
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Affiliation(s)
- A M K Hansen
- Diabetes Research Unit, Novo Nordisk A/S, Måløv, Denmark
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Rezania A, Riedel MJ, Wideman RD, Karanu F, Ao Z, Warnock GL, Kieffer TJ. Production of functional glucagon-secreting α-cells from human embryonic stem cells. Diabetes 2011; 60:239-47. [PMID: 20971966 PMCID: PMC3012176 DOI: 10.2337/db10-0573] [Citation(s) in RCA: 146] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
OBJECTIVE Differentiation of human embryonic stem (hES) cells to fully developed cell types holds great therapeutic promise. Despite significant progress, the conversion of hES cells to stable, fully differentiated endocrine cells that exhibit physiologically regulated hormone secretion has not yet been achieved. Here we describe an efficient differentiation protocol for the in vitro conversion of hES cells to functional glucagon-producing α- cells. RESEARCH DESIGN AND METHODS Using a combination of small molecule screening and empirical testing, we developed a six-stage differentiation protocol for creating functional α-cells. An extensive in vitro and in vivo characterization of the differentiated cells was performed. RESULTS A high rate of synaptophysin expression (>75%) and robust expression of glucagon and the α-cell transcription factor ARX was achieved. After a transient polyhormonal state in which cells coexpress glucagon and insulin, maturation in vitro or in vivo resulted in depletion of insulin and other β-cell markers with concomitant enrichment of α-cell markers. After transplantation, these cells secreted fully processed, biologically active glucagon in response to physiologic stimuli including prolonged fasting and amino acid challenge. Moreover, glucagon release from transplanted cells was sufficient to reduce demand for pancreatic glucagon, resulting in a significant decrease in pancreatic α-cell mass. CONCLUSIONS These results indicate that fully differentiated pancreatic endocrine cells can be created via stepwise differentiation of hES cells. These cells may serve as a useful screening tool for the identification of compounds that modulate glucagon secretion as well as those that promote the transdifferentiation of α-cells to β-cells.
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Affiliation(s)
- Alireza Rezania
- BetaLogics Venture, Centocor Research and Development, Skillman, New Jersey
| | - Michael J. Riedel
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Rhonda D. Wideman
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Francis Karanu
- BetaLogics Venture, Centocor Research and Development, Skillman, New Jersey
| | - Ziliang Ao
- Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada
| | - Garth L. Warnock
- Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada
| | - Timothy J. Kieffer
- Laboratory of Molecular and Cellular Medicine, 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
- Corresponding author: Timothy J. Kieffer,
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Abstract
Building on the elaborate research studies that have helped map out key decision points in the process of pancreas development, reprogramming of pluripotent embryonic stem cells or induced pluripotent stem cells offers the possibility of overcoming restrictions on tissue supply associated with transplantation of donor islets. In a healthy pancreas, the beta-cell mass can exhibit significant plasticity, as reflected in the normal adaptive response in beta-cell mass to offset the metabolic challenge associated with pregnancy and obesity. In this article, alternative strategies and potential sources of pancreatic stem cells are considered.
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Kalousova A, Mavropoulos A, Adams BA, Nekrep N, Li Z, Krauss S, Stainier DY, German MS. Dachshund homologues play a conserved role in islet cell development. Dev Biol 2010; 348:143-52. [PMID: 20869363 DOI: 10.1016/j.ydbio.2010.09.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2010] [Revised: 09/03/2010] [Accepted: 09/15/2010] [Indexed: 01/09/2023]
Abstract
All metazoans use insulin to control energy metabolism, but they secrete it from different cells: neurons in the central nervous system in invertebrates and endocrine cells in the gut or pancreas in vertebrates. Despite their origins in different germ layers, all of these insulin-producing cells share common functional features and gene expression patterns. In this study, we tested the role in insulin-producing cells of the vertebrate homologues of Dachshund, a transcriptional regulator that marks the earliest committed progenitors of the neural insulin-producing cells in Drosophila. Both zebrafish and mice expressed a single dominant Dachshund homologue in the pancreatic endocrine lineage, and in both species loss of this homologue reduced the numbers of all islet cell types including the insulin-producing β-cells. In mice, Dach1 gene deletion left the pancreatic progenitor cells unaltered, but blocked the perinatal burst of proliferation of differentiated β-cells that normally generates most of the β-cell mass. In β-cells, Dach1 bound to the promoter of the cell cycle inhibitor p27Kip1, which constrains β-cell proliferation. Taken together, these data demonstrate a conserved role for Dachshund homologues in the production of insulin-producing cells.
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Affiliation(s)
- Anna Kalousova
- Diabetes Center, University of California, San Francisco, San Francisco, CA 94143, USA
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Xie T, Chen M, Weinstein LS. Pancreas-specific Gsalpha deficiency has divergent effects on pancreatic alpha- and beta-cell proliferation. J Endocrinol 2010; 206:261-9. [PMID: 20543009 PMCID: PMC2929693 DOI: 10.1677/joe-10-0030] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The ubiquitously expressed G protein alpha-subunit G(s)alpha mediates the intracellular cAMP response to glucagon-like peptide 1 (GLP1) and other incretin hormones in pancreatic islet cells. We have shown previously that mice with beta-cell-specific G(s)alpha deficiency (betaGsKO) develop severe early-onset insulin-deficient diabetes with a severe defect in beta-cell proliferation. We have now generated mice with G(s)alpha deficiency throughout the whole pancreas by mating G(s)alpha-floxed mice with Pdx1-cre transgenic mice (PGsKO). PGsKO mice also developed severe insulin-deficient diabetes at a young age, confirming the important role of G(s)alpha signaling in beta-cell growth and function. Unlike in betaGsKO mice, islets in PGsKO mice had a relatively greater proportion of alpha-cells, which were spread throughout the interior of the islet. Similar findings were observed in mice with pancreatic islet cell-specific G(s)alpha deficiency using a neurogenin 3 promoter-cre recombinase transgenic mouse line. Studies in the alpha-cell line alphaTC1 confirmed that reduced cAMP signaling increased cell proliferation while increasing cAMP produced the opposite effect. Therefore, it appears that G(s)alpha/cAMP signaling has opposite effects on pancreatic alpha- and beta-cell proliferation, and that impaired GLP1 action in alpha- and beta-cells via G(s)alpha signaling may be an important contributor to the reciprocal effects on insulin and glucagon observed in type 2 diabetics. In addition, PGsKO mice show morphological changes in exocrine pancreas and evidence for malnutrition and dehydration, indicating an important role for G(s)alpha in the exocrine pancreas as well.
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Affiliation(s)
- Tao Xie
- Signal Transduction Section, Metabolic Diseases Branch, National Institute of Diabetes, Digestive, and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
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Kilimnik G, Kim A, Steiner DF, Friedman TC, Hara M. Intraislet production of GLP-1 by activation of prohormone convertase 1/3 in pancreatic α-cells in mouse models of ß-cell regeneration. Islets 2010; 2:149-55. [PMID: 20657753 PMCID: PMC2908328 DOI: 10.4161/isl.2.3.11396] [Citation(s) in RCA: 104] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The islet of Langerhans is a highly vascularized micro-organ consisting of not only ß-cells but multiple cell types such as α-, delta-, pancreatic polypeptide- and epsilon-cells that work together to regulate glucose homeostatis. We have recently proposed a new model of the neonatal islet formation in mice by a process of fission following contiguous endocrine cell proliferation in the form of branched cord-like structures in embryos and newborns. There exist large stretches of interconnected islet structures along large blood vessels in the neonatal pancreas, which, upon further development, segregate into smaller fragments (i.e., islets) that eventually become more spherical by internal proliferation as seen in the adult pancreas. α-cells span these elongated islet-like structures in the developing pancreas, which we hypothesize represent sites of fission and facilitate the eventual formation of discrete islets. The α-cells express both prohormone convertase 2 and 1/3 (PC 2 and PC 1/3, respectively), which resulted in the processing of the proglucagon precursor into glucagon-like peptide 1, thereby leading to local production of this important ß-cell growth factor. Furthermore, while α-cells in the adult basically only express PC 2, significant activation of PC 1/3 is also observed in mouse models of insulin resistance such as pregnant, ob/ ob, db/db and prediabetic NOD mice, which may be a common mechanism in proliferating ß-cells. Our study suggests an important role of α-cells for ß-cell proliferation and further for the endocrine cell network within an islet.
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Affiliation(s)
- German Kilimnik
- Department of Medicine; The University of Chicago; Chicago, IL USA
| | - Abraham Kim
- Department of Medicine; The University of Chicago; Chicago, IL USA
| | | | - Theodore C. Friedman
- Divison of Endocrinology; Department of Internal Medicine; Charles Drew University of Medicine & Sciences; Los Angeles, CA USA
| | - Manami Hara
- Department of Medicine; The University of Chicago; Chicago, IL USA
- Correspondence to: Manami Hara;
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Fujita Y, Wideman RD, Asadi A, Yang GK, Baker R, Webber T, Zhang T, Wang R, Ao Z, Warnock GL, Kwok YN, Kieffer TJ. Glucose-dependent insulinotropic polypeptide is expressed in pancreatic islet alpha-cells and promotes insulin secretion. Gastroenterology 2010; 138:1966-75. [PMID: 20138041 DOI: 10.1053/j.gastro.2010.01.049] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2008] [Revised: 01/19/2010] [Accepted: 01/27/2010] [Indexed: 02/08/2023]
Abstract
BACKGROUND & AIMS Glucose-dependent insulinotropic polypeptide (GIP) and the proglucagon product glucagon-like peptide-1 (GLP-1) are gastrointestinal hormones that are released in response to nutrient intake and promote insulin secretion. Interestingly, a subset of enteroendocrine cells express both GIP and GLP-1. We sought to determine whether GIP also might be co-expressed with proglucagon in pancreatic alpha-cells. METHODS We assessed GIP expression via reverse-transcription polymerase chain reaction, in situ hybridization, and immunohistochemistry. We developed a novel bioassay to measure GIP release from isolated islets, compared the biological activities of full-length and truncated GIP, and assessed the impact of immunoneutralization of islet GIP on glucose-stimulated insulin secretion in isolated islets. RESULTS GIP messenger RNA was present in mouse islets; GIP protein localized to islet alpha-cells of mouse, human, and snake pancreas, based on immunohistochemical analyses. However, using a C-terminal GIP antibody, immunoreactivity was detected in islets from prohormone convertase (PC) 2 knockout but not wild-type mice. Bioactive GIP was secreted from mouse and human islets after arginine stimulation. In the perfused mouse pancreas, GIP(1-42) and amidated GIP(1-30) had equipotent insulinotropic actions. Finally, immunoneutralization of GIP secreted by isolated islets decreased glucose-stimulated insulin secretion. CONCLUSIONS GIP is expressed in and secreted from pancreatic islets; in alpha-cells, PC2 processes proGIP to yield a truncated but bioactive form of GIP that differs from the PC1/3-derived form from K-cells. Islet-derived GIP promotes islet glucose competence and also could support islet development and/or survival.
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Affiliation(s)
- Yukihiro Fujita
- Laboratory of Molecular and Cellular Medicine, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
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Abstract
OBJECTIVE Despite great progress in understanding the transcriptional regulation of the development of insulin-secreting beta cells, the quantitative temporal expression of insulin gene(s) remains largely unknown. We here aimed to quantify insulin gene transcripts during development. METHODS We described bioinformatics algorithms to quantify (insulin) gene transcript abundance in sequential microarray data sets at the global level. Several molecular techniques were used to confirm our analyses. RESULTS We demonstrated that the expression of insulin genes was up-regulated at approximately 14-fold, 700- to 2000-fold, and 5000- to 6000-fold in Pdx1- and Ngn3-expressing cells and adult islets compared with definitive endodermal or embryonic stem cells, respectively. The expression of multiple genes encoding molecules involved in posttranslational modifications of insulin and glucose sensing was also elevated in the same period. All islet and associated genes determined with microarray data were confirmed not only to be up-regulated by real-time quantitative reverse transcriptase polymerase chain reaction but also that the magnitude of their increase quantified with these 2 methods was statistically highly correlated. Consistent with the above, green fluorescence protein expression under the control of the mouse insulin 1 promoter could be visualized in the pancreas from embryonic day (E) 11.5, increasing progressively through E13.5 to E15.5. CONCLUSION Our study provides a novel insight into islet developmental biology.
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Halban PA, German MS, Kahn SE, Weir GC. Current status of islet cell replacement and regeneration therapy. J Clin Endocrinol Metab 2010; 95:1034-43. [PMID: 20061422 PMCID: PMC2841538 DOI: 10.1210/jc.2009-1819] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
CONTEXT Beta cell mass and function are decreased to varying degrees in both type 1 and type 2 diabetes. In the future, islet cell replacement or regeneration therapy may thus offer therapeutic benefit to people with diabetes, but there are major challenges to be overcome. EVIDENCE ACQUISITION A review of published peer-reviewed medical literature on beta-cell development and regeneration was performed. Only publications considered most relevant were selected for citation, with particular attention to the period 2000-2009 and the inclusion of earlier landmark studies. EVIDENCE SYNTHESIS Islet cell regenerative therapy could be achieved by in situ regeneration or implantation of cells previously derived in vitro. Both approaches are being explored, and their ultimate success will depend on the ability to recapitulate key events in the normal development of the endocrine pancreas to derive fully differentiated islet cells that are functionally normal. There is also debate as to whether beta-cells alone will assure adequate metabolic control or whether it will be necessary to regenerate islets with their various cell types and unique integrated function. Any approach must account for the potential dangers of regenerative therapy. CONCLUSIONS Islet cell regenerative therapy may one day offer an improved treatment of diabetes and potentially a cure. However, the various approaches are at an early stage of preclinical development and should not be offered to patients until shown to be safe as well as more efficacious than existing therapy.
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Affiliation(s)
- Philippe A Halban
- Department of Genetic Medicine and Development, University of Geneva, University Medical Center, 1 Rue Michel-Servet, 1211 Geneva 4, Switzerland.
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Transcriptional Control of Acinar Development and Homeostasis. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2010; 97:1-40. [DOI: 10.1016/b978-0-12-385233-5.00001-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Abstract
Diabetes is characterized by decreased function of insulin-producing beta cells and insufficient insulin output resulting from an absolute (Type 1) or relative (Type 2) inadequate functional beta cell mass. Both forms of the disease would greatly benefit from treatment strategies that could enhance beta cell regeneration and/or function. Successful and reliable methods of generating beta cells or whole islets from progenitor cells in vivo or in vitro could lead to restoration of beta cell mass in individuals with Type 1 diabetes and enhanced beta cell compensation in Type 2 patients. A thorough understanding of the normal developmental processes that occur during pancreatic organogenesis, for example, transcription factors, cell signaling molecules, and cell-cell interactions that regulate endocrine differentiation from the embryonic pancreatic epithelium, is required in order to successfully reach these goals. This review summarizes our current understanding of pancreas development, with particular emphasis on factors intrinsic or extrinsic to the pancreatic epithelium that are involved in regulating the development and differentiation of the various pancreatic cell types. We also discuss the recent progress in generating insulin-producing cells from progenitor sources.
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Affiliation(s)
- Michelle A Guney
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
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36
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Homozygous P86S mutation of the human glucagon receptor is associated with hyperglucagonemia, alpha cell hyperplasia, and islet cell tumor. Pancreas 2009; 38:941-6. [PMID: 19657311 PMCID: PMC2767399 DOI: 10.1097/mpa.0b013e3181b2bb03] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
OBJECTIVE The goal of the study was to investigate the genetic and molecular basis of a novel syndrome of marked hyperglucagonemia and pancreatic alpha cell hyperplasia without glucagonoma syndrome. METHODS The glucagon receptor (GCGR) gene and the glucagon gene were sequenced in a patient with hyperglucagonemia and pancreatic alpha cell hyperplasia without glucagonoma syndrome. Enhanced green fluorescent protein-conjugated wild type (WT) and mutant GCGR were used to characterize the functions of the mutant GCGR. RESULTS The glucagon gene sequence was normal, but the GCGR sequencing uncovered a homozygous missense mutation, c.256C>T, p.P86S in the extracellular domain of GCGR. When expressed in human embryonic kidney 293 cells, GCGR P86S localized to the plasma membrane but bound 96% less radiolabeled glucagon than WT GCGR. The median effective concentration of glucagon-induced cyclic adenosine monophosphate production was 24 nmol/L for GCGR P86S but 2.4 nmol/L for WT GCGR. The patient's alpha cells also express glucagonlike peptide 1 and pancreatic polypeptide. CONCLUSIONS We hereby report the first homozygous missense mutation in the human GCGR, which is associated with alpha cell hyperplasia and hyperglucagonemia. This mutation lowers the receptor's affinity to glucagon and decreases cyclic adenosine monophosphate production with physiological concentrations of glucagon. Thus, the P86S mutation in GCGR likely causes alpha cell hyperplasia and hyperglucagonemia.
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37
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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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38
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Derivation of insulin-producing cells from human embryonic stem cells. Stem Cell Res 2009; 3:73-87. [DOI: 10.1016/j.scr.2009.08.003] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2009] [Revised: 08/01/2009] [Accepted: 08/18/2009] [Indexed: 12/21/2022] Open
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Wideman RD, Kieffer TJ. Mining incretin hormone pathways for novel therapies. Trends Endocrinol Metab 2009; 20:280-6. [PMID: 19595611 DOI: 10.1016/j.tem.2009.02.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2008] [Revised: 01/30/2009] [Accepted: 02/02/2009] [Indexed: 10/20/2022]
Abstract
The incretin hormones, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1), are produced predominantly by enteroendocrine cells and have multiple blood glucose-lowering effects. Recent years have seen a surge of interest in understanding the basic physiology and pathophysiology of incretins and in applying this knowledge to the treatment of diabetes and obesity. Considerable gains have been made in elucidating the mechanisms controlling incretin secretion, and there is growing evidence to suggest that incretins might be involved in the rapid reversal of diabetes observed in gastric bypass patients. Here, we review these recent advances and outline the multiple strategies being pursued to exploit the potential therapeutic benefits of GIP and GLP-1.
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Affiliation(s)
- Rhonda D Wideman
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada
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40
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Abstract
The glucagon gene is expressed not only in the alpha cells of the pancreatic islets but also in the endocrine cells of the intestinal epithelium (so-called L-cells), and in certain neurons of the brain stem. Whereas in the pancreas, glucagon, the hyperglycaemic hormone, is cleaved out of the 160 amino acid precursor, proglucagon, leaving behind proglucagon fragments (PG 1-30 and PG 72-158, the so-called major proglucagon fragment (MPGF)) that are probably inactive, the intestinal processing leads to the formation of glicentin (PG 1-69; action uncertain) and glucagon-like peptides 1 (PG 78-107amide, a potent incretin homone, regulating insulin secretion, glucagon secretion, gastrointestinal motility and appetite) and 2 (PG 126-158, a regulator of gut mucosal growth and integrity). The two prohormone convertases PC2 and PC1/3, respectively, are responsible for the differential processing. After their release, the hormones are eliminated mainly in the kidneys, but both GLP-2 and in particular GLP-1, but not glucagon, are metabolized both locally and in the circulation and liver by dipeptidyl peptidase 4 (DPP-4) which inactivates the peptides, suggesting that GLP-1 acts locally rather than in an endocrine manner. A number of transcription factors have been identified that can at least partly explain the differential cellular expression of the glucagon gene as well as the differential tissue-specific processing of the precursor.
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Affiliation(s)
- Jens Juul Holst
- Department of Biomedical Sciences, The Panum Institute, University of Copenhagen, 2200, Copenhagen, Denmark.
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41
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Gittes GK. Developmental biology of the pancreas: a comprehensive review. Dev Biol 2008; 326:4-35. [PMID: 19013144 DOI: 10.1016/j.ydbio.2008.10.024] [Citation(s) in RCA: 300] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2008] [Revised: 10/09/2008] [Accepted: 10/13/2008] [Indexed: 02/06/2023]
Abstract
Pancreatic development represents a fascinating process in which two morphologically distinct tissue types must derive from one simple epithelium. These two tissue types, exocrine (including acinar cells, centro-acinar cells, and ducts) and endocrine cells serve disparate functions, and have entirely different morphology. In addition, the endocrine tissue must become disconnected from the epithelial lining during its development. The pancreatic development field has exploded in recent years, and numerous published reviews have dealt specifically with only recent findings, or specifically with certain aspects of pancreatic development. Here I wish to present a more comprehensive review of all aspects of pancreatic development, though still there is not a room for discussion of stem cell differentiation to pancreas, nor for discussion of post-natal regeneration phenomena, two important fields closely related to pancreatic development.
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Affiliation(s)
- George K Gittes
- Children's Hospital of Pittsburgh and the University of Pittsburgh School of Medicine, Department of Pediatric Surgery, 3705 Fifth Avenue, Pittsburgh, PA 15213, USA
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Wang Q, Elghazi L, Martin S, Martins I, Srinivasan RS, Geng X, Sleeman M, Collombat P, Houghton J, Sosa-Pineda B. Ghrelin is a novel target of Pax4 in endocrine progenitors of the pancreas and duodenum. Dev Dyn 2008; 237:51-61. [PMID: 18058910 DOI: 10.1002/dvdy.21379] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Pax4-deficient mice have a severe gastrointestinal endocrine deficiency: they lack most pancreatic cells that produce insulin or somatostatin and various duodenal endocrine cell types. Remarkably, Pax4-deficient mice also have an overabundance of ghrelin-expressing cells in the pancreas and duodenum. Detailed analysis of the Pax4 nullizygous pancreas determined that the mutant islets are largely composed of a distinctive endocrine cell type that expresses ghrelin, glucagon, islet amyloid polypeptide (IAPP), and low levels of Pdx1. Lineage-tracing analysis revealed that most of these unique endocrine cells directly arose from Pax4-deficient progenitors. Previous in vitro work reported that Pax4 is a transcriptional repressor of islet amyloid polypeptide (IAPP) and glucagon. In this study, we expanded those results by showing that Pax4 is also a repressor of gherlin. Together, our data further support the notion that Pax4 activity is necessary to establish appropriate patterns of gene expression in endocrine progenitors of the digestive tract.
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Affiliation(s)
- Qian Wang
- Department of Genetics and Tumor Cell Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
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Wang S, Hecksher-Sorensen J, Xu Y, Zhao A, Dor Y, Rosenberg L, Serup P, Gu G. Myt1 and Ngn3 form a feed-forward expression loop to promote endocrine islet cell differentiation. Dev Biol 2008; 317:531-40. [PMID: 18394599 DOI: 10.1016/j.ydbio.2008.02.052] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2008] [Revised: 02/26/2008] [Accepted: 02/27/2008] [Indexed: 10/22/2022]
Abstract
High levels of Ngn3 expression in pancreatic progenitor cells are both necessary and sufficient to initiate endocrine differentiation. While it is clear that the Notch-Hes1-mediated signals control the number of Ngn3-expressing cells in the developing pancreas, it is not known what factors control the level of Ngn3 expression in individual pancreatic cells. Here we report that Myt1b and Ngn3 form a feed-forward expression loop that regulates endocrine differentiation. Myt1b induces glucagon expression by potentiating Ngn3 transcription in pancreatic progenitors. Vice versa, Ngn3 protein production induces the expression of Myt1. Furthermore, pancreatic Myt1 expression largely, but not totally, relies on Ngn3 activity. Surprisingly, a portion of Myt1 expressing pancreatic cells express glucagon and other alpha cell markers in Ngn3 nullizygous mutant animals. These results demonstrate that Myt1b and Ngn3 positively regulate each other's expression to promote endocrine differentiation. In addition, the data uncover an unexpected Ngn3 expression-independent endocrine cell production pathway, which further bolsters the notion that the seemingly equivalent endocrine cells of each type, as judged by hormone and transcription factor expression, are heterogeneous in their origin.
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Affiliation(s)
- Sui Wang
- Program in Developmental Biology, Department of Cell and Developmental Biology, 465 21st Avenue South, Rm 4128, Vanderbilt University Medical Center, Nashville, TN 37232, USA
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Kroon E, Martinson LA, Kadoya K, Bang AG, Kelly OG, Eliazer S, Young H, Richardson M, Smart NG, Cunningham J, Agulnick AD, D'Amour KA, Carpenter MK, Baetge EE. Pancreatic endoderm derived from human embryonic stem cells generates glucose-responsive insulin-secreting cells in vivo. Nat Biotechnol 2008; 26:443-52. [PMID: 18288110 DOI: 10.1038/nbt1393] [Citation(s) in RCA: 1265] [Impact Index Per Article: 79.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2007] [Accepted: 02/12/2008] [Indexed: 02/06/2023]
Abstract
Development of a cell therapy for diabetes would be greatly aided by a renewable supply of human beta-cells. Here we show that pancreatic endoderm derived from human embryonic stem (hES) cells efficiently generates glucose-responsive endocrine cells after implantation into mice. Upon glucose stimulation of the implanted mice, human insulin and C-peptide are detected in sera at levels similar to those of mice transplanted with approximately 3,000 human islets. Moreover, the insulin-expressing cells generated after engraftment exhibit many properties of functional beta-cells, including expression of critical beta-cell transcription factors, appropriate processing of proinsulin and the presence of mature endocrine secretory granules. Finally, in a test of therapeutic potential, we demonstrate that implantation of hES cell-derived pancreatic endoderm protects against streptozotocin-induced hyperglycemia. Together, these data provide definitive evidence that hES cells are competent to generate glucose-responsive, insulin-secreting cells.
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Affiliation(s)
- Evert Kroon
- Novocell, Inc., 3550 General Atomics Ct., San Diego, California 92121, USA
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Masui T, Long Q, Beres TM, Magnuson MA, MacDonald RJ. Early pancreatic development requires the vertebrate Suppressor of Hairless (RBPJ) in the PTF1 bHLH complex. Genes Dev 2007; 21:2629-43. [PMID: 17938243 DOI: 10.1101/gad.1575207] [Citation(s) in RCA: 129] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PTF1a is an unusual basic helix-loop-helix (bHLH) transcription factor that is required for the development of the pancreas. We show that early in pancreatic development, active PTF1a requires interaction with RBPJ, the vertebrate Suppressor of Hairless, within a stable trimeric DNA-binding complex (PTF1). Later, as acinar cell development begins, RBPJ is swapped for RBPJL, the constitutively active, pancreas-restricted paralog of RBPJ. Moreover, the Rbpjl gene is a direct target of the PTF1 complex: At the onset of acinar cell development when the Rbpjl gene is first induced, a PTF1 complex containing RBPJ is bound to the Rbpjl promoter. As development proceeds, RBPJL gradually replaces RBPJ in the PTF1 complex bound to Rbpjl and appears on the binding sites for the complex in the promoters of other acinar-specific genes, including those for the secretory digestive enzymes. A single amino acid change in PTF1a that eliminates its ability to bind RBPJ (but does not affect its binding to RBPJL) causes pancreatic development to truncate at an immature stage, without the formation of acini or islets. These results indicate that the interaction between PTF1a and RBPJ is required for the early stage of pancreatic growth, morphogenesis, and lineage fate decisions. The defects in pancreatic development phenocopy those of Ptf1a-null embryos; thus, the first critical function of PTF1a is in the context of the PTF1 complex containing RBPJ. Action within an organ-specific transcription factor is a previously unknown function for RBPJ and is independent of its role in Notch signaling.
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Affiliation(s)
- Toshihiko Masui
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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46
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Gannon M, Ables ET, Crawford L, Lowe D, Offield MF, Magnuson MA, Wright CVE. pdx-1 function is specifically required in embryonic beta cells to generate appropriate numbers of endocrine cell types and maintain glucose homeostasis. Dev Biol 2007; 314:406-17. [PMID: 18155690 DOI: 10.1016/j.ydbio.2007.10.038] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2007] [Accepted: 10/16/2007] [Indexed: 10/22/2022]
Abstract
The pdx1 gene is essential for pancreatic organogenesis in humans and mice; pdx1 mutations have been identified in human diabetic patients. Specific inactivation of pdx1 in adult beta cells revealed that this gene is required for maintenance of mature beta cell function. In the following study, a Cre-lox strategy was used to remove pdx1 function specifically from embryonic beta cells beginning at late-gestation, prior to islet formation. Animals in which pdx1 is lost in insulin-producing cells during embryogenesis had elevated blood glucose levels at birth and were overtly diabetic by weaning. Neonatal and adult mutant islets showed a dramatic reduction in the number of insulin(+) cells and an increase in both glucagon(+) and somatostatin(+) cells. Lineage tracing revealed that excess glucagon(+) and somatostatin(+) cells did not arise by interconversion of endocrine cell types. Examination of mutant islets revealed a decrease in proliferation of insulin-producing cells just before birth and a concomitant increase in proliferation of glucagon-producing cells. We propose that pdx1 is required for proliferation and function of the beta cells generated at late gestation, and that one function of normal beta cells is to inhibit the proliferation of other islet cell types, resulting in the appropriate numbers of the different endocrine cell types.
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Affiliation(s)
- Maureen Gannon
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
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47
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Wideman RD, Covey SD, Webb GC, Drucker DJ, Kieffer TJ. A switch from prohormone convertase (PC)-2 to PC1/3 expression in transplanted alpha-cells is accompanied by differential processing of proglucagon and improved glucose homeostasis in mice. Diabetes 2007; 56:2744-52. [PMID: 17698597 DOI: 10.2337/db07-0563] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE Glucagon, which raises blood glucose levels by stimulating hepatic glucose production, is produced in alpha-cells via cleavage of proglucagon by prohormone convertase (PC)-2. In the enteroendocrine L-cell, proglucagon is differentially processed by the alternate enzyme PC1/3 to yield glucagon-like peptide (GLP)-1, GLP-2, and oxyntomodulin, which have blood glucose-lowering effects. We hypothesized that alteration of PC expression in alpha-cells might convert the alpha-cell from a hyperglycemia-promoting cell to one that would improve glucose homeostasis. RESEARCH DESIGN AND METHODS We compared the effect of transplanting encapsulated PC2-expressing alpha TC-1 cells with PC1/3-expressing alpha TCDeltaPC2 cells in normal mice and low-dose streptozotocin (STZ)-treated mice. RESULTS Transplantation of PC2-expressing alpha-cells increased plasma glucagon levels and caused mild fasting hyperglycemia, impaired glucose tolerance, and alpha-cell hypoplasia. In contrast, PC1/3-expressing alpha-cells increased plasma GLP-1/GLP-2 levels, improved glucose tolerance, and promoted beta-cell proliferation. In GLP-1R(-/-) mice, the ability of PC1/3-expressing alpha-cells to improve glucose tolerance was attenuated. Transplantation of PC1/3-expressing alpha-cells prevented STZ-induced hyperglycemia by preserving beta-cell area and islet morphology, possibly via stimulating beta-cell replication. However, PC2-expressing alpha-cells neither prevented STZ-induced hyperglycemia nor increased beta-cell proliferation. Transplantation of alpha TCDeltaPC2, but not alpha TC-1 cells, also increased intestinal epithelial proliferation. CONCLUSIONS Expression of PC1/3 rather than PC2 in alpha-cells induces GLP-1 and GLP-2 production and converts the alpha-cell from a hyperglycemia-promoting cell to one that lowers blood glucose levels and promotes islet survival. This suggests that alteration of proglucagon processing in the alpha-cell may be therapeutically useful in the context of diabetes.
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Affiliation(s)
- Rhonda D Wideman
- Department of Cellular and Physiological Sciences, Laboratory of Molecular and Cellular Medicine, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
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Lynn FC, Smith SB, Wilson ME, Yang KY, Nekrep N, German MS. Sox9 coordinates a transcriptional network in pancreatic progenitor cells. Proc Natl Acad Sci U S A 2007; 104:10500-5. [PMID: 17563382 PMCID: PMC1965542 DOI: 10.1073/pnas.0704054104] [Citation(s) in RCA: 182] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
During pancreas development, both the exocrine and endocrine lineages differentiate from a common pool of progenitor cells with similarities to mature pancreatic duct cells. A small set of transcription factors, including Tcf2, Onecut1, and Foxa2, has been identified in these pancreatic progenitor cells. The Sry/HMG box transcription factor Sox9 is also expressed in the early pancreatic epithelium and is required for normal pancreatic exocrine and endocrine development in humans. In this study, we found Sox9 in mice specifically expressed with the other progenitor transcription factors in both pancreatic progenitor cells and duct cells in the adult pancreas. Sox9 directly bound to all three genes in vitro and in intact cells, and regulated their expression. In turn, both Foxa2 and Tcf2 regulated Sox9 expression, demonstrating feedback circuits between these genes. Furthermore, Sox9 activated the expression of the proendocrine factor Neurogenin3, which also depends on the other members of the progenitor transcription network. These studies indicate that Sox9 plays a dual role in pancreatic progenitor cells: both maintaining a stable transcriptional network and supporting the programs by which these cells differentiate into distinct lineages.
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Affiliation(s)
- F. C. Lynn
- *Diabetes Center, Hormone Research Institute, and
| | - S. B. Smith
- *Diabetes Center, Hormone Research Institute, and
| | - M. E. Wilson
- *Diabetes Center, Hormone Research Institute, and
| | - K. Y. Yang
- *Diabetes Center, Hormone Research Institute, and
| | - N. Nekrep
- *Diabetes Center, Hormone Research Institute, and
| | - M. S. German
- Department of Medicine, University of California, San Francisco, CA 94143
- To whom correspondence should be addressed at:
University of California Diabetes Center, 513 Parnassus Avenue, San Francisco, CA 94143-0534. E-mail:
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Doyle ME, Egan JM. Mechanisms of action of glucagon-like peptide 1 in the pancreas. Pharmacol Ther 2007; 113:546-93. [PMID: 17306374 PMCID: PMC1934514 DOI: 10.1016/j.pharmthera.2006.11.007] [Citation(s) in RCA: 482] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2006] [Accepted: 11/27/2006] [Indexed: 12/13/2022]
Abstract
Glucagon-like peptide 1 (GLP-1) is a hormone that is encoded in the proglucagon gene. It is mainly produced in enteroendocrine L cells of the gut and is secreted into the blood stream when food containing fat, protein hydrolysate, and/or glucose enters the duodenum. Its particular effects on insulin and glucagon secretion have generated a flurry of research activity over the past 20 years culminating in a naturally occurring GLP-1 receptor (GLP-1R) agonist, exendin 4 (Ex-4), now being used to treat type 2 diabetes mellitus (T2DM). GLP-1 engages a specific guanine nucleotide-binding protein (G-protein) coupled receptor (GPCR) that is present in tissues other than the pancreas (brain, kidney, lung, heart, and major blood vessels). The most widely studied cell activated by GLP-1 is the insulin-secreting beta cell where its defining action is augmentation of glucose-induced insulin secretion. Upon GLP-1R activation, adenylyl cyclase (AC) is activated and cAMP is generated, leading, in turn, to cAMP-dependent activation of second messenger pathways, such as the protein kinase A (PKA) and Epac pathways. As well as short-term effects of enhancing glucose-induced insulin secretion, continuous GLP-1R activation also increases insulin synthesis, beta cell proliferation, and neogenesis. Although these latter effects cannot be currently monitored in humans, there are substantial improvements in glucose tolerance and increases in both first phase and plateau phase insulin secretory responses in T2DM patients treated with Ex-4. This review will focus on the effects resulting from GLP-1R activation in the pancreas.
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Affiliation(s)
- Máire E Doyle
- Department of Pathology, Immunology & Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL, USA
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50
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Gromada J, Franklin I, Wollheim CB. Alpha-cells of the endocrine pancreas: 35 years of research but the enigma remains. Endocr Rev 2007; 28:84-116. [PMID: 17261637 DOI: 10.1210/er.2006-0007] [Citation(s) in RCA: 419] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Glucagon, a hormone secreted from the alpha-cells of the endocrine pancreas, is critical for blood glucose homeostasis. It is the major counterpart to insulin and is released during hypoglycemia to induce hepatic glucose output. The control of glucagon secretion is multifactorial and involves direct effects of nutrients on alpha-cell stimulus-secretion coupling as well as paracrine regulation by insulin and zinc and other factors secreted from neighboring beta- and delta-cells within the islet of Langerhans. Glucagon secretion is also regulated by circulating hormones and the autonomic nervous system. In this review, we describe the components of the alpha-cell stimulus secretion coupling and how nutrient metabolism in the alpha-cell leads to changes in glucagon secretion. The islet cell composition and organization are described in different species and serve as a basis for understanding how the numerous paracrine, hormonal, and nervous signals fine-tune glucagon secretion under different physiological conditions. We also highlight the pathophysiology of the alpha-cell and how hyperglucagonemia represents an important component of the metabolic abnormalities associated with diabetes mellitus. Therapeutic inhibition of glucagon action in patients with type 2 diabetes remains an exciting prospect.
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Affiliation(s)
- Jesper Gromada
- Novartis Institutes for BioMedical Research, 100 Technology Square, Cambridge, Massachusetts 02139, USA.
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