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Abstract
AIMS/HYPOTHESIS The endocrine pancreas comprises the islets of Langerhans, primarily consisting of beta cells, alpha cells and delta cells responsible for secretion of insulin, glucagon and somatostatin, respectively. A certain level of intra-islet communication is thought to exist, where the individual hormones may reach the other islet cells and regulate their secretion. Glucagon has been demonstrated to importantly regulate insulin secretion, while somatostatin powerfully inhibits both insulin and glucagon secretion. In this study we investigated how secretion of somatostatin is regulated by paracrine signalling from glucagon and insulin. METHODS Somatostatin secretion was measured from perfused mouse pancreases isolated from wild-type as well as diphtheria toxin-induced alpha cell knockdown, and global glucagon receptor knockout (Gcgr-/-) mice. We studied the effects of varying glucose concentrations together with infusions of arginine, glucagon, insulin and somatostatin, as well as infusions of antagonists of insulin, somatostatin and glucagon-like peptide 1 (GLP-1) receptors. RESULTS A tonic inhibitory role of somatostatin was demonstrated with infusion of somatostatin receptor antagonists, which significantly increased glucagon secretion at low and high glucose, whereas insulin secretion was only increased at high glucose levels. Infusion of glucagon dose-dependently increased somatostatin secretion approximately twofold in control mice. Exogenous glucagon had no effect on somatostatin secretion in Gcgr-/- mice, and a reduced effect when combined with the GLP-1 receptor antagonist exendin 9-39. Diphtheria toxin-induced knockdown of glucagon producing cells led to reduced somatostatin secretion in response to 12 mmol/l glucose and arginine infusions. In Gcgr-/- mice (where glucagon levels are dramatically increased) overall somatostatin secretion was increased. However, infusion of exendin 9-39 in Gcgr-/- mice completely abolished somatostatin secretion in response to glucose and arginine. Neither insulin nor an insulin receptor antagonist (S961) had any effect on somatostatin secretion. CONCLUSIONS/INTERPRETATION Our findings demonstrate that somatostatin and glucagon secretion are linked in a reciprocal feedback cycle with somatostatin inhibiting glucagon secretion at low and high glucose levels, and glucagon stimulating somatostatin secretion via the glucagon and GLP-1 receptors. Graphical abstract.
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Affiliation(s)
- Berit Svendsen
- NovoNordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
| | - Jens J Holst
- NovoNordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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2
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Avrahami D, Wang YJ, Schug J, Feleke E, Gao L, Liu C, Naji A, Glaser B, Kaestner KH. Single-cell transcriptomics of human islet ontogeny defines the molecular basis of β-cell dedifferentiation in T2D. Mol Metab 2020; 42:101057. [PMID: 32739450 PMCID: PMC7471622 DOI: 10.1016/j.molmet.2020.101057] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Revised: 07/20/2020] [Accepted: 07/27/2020] [Indexed: 01/03/2023] Open
Abstract
OBJECTIVE Dedifferentiation of pancreatic β-cells may reduce islet function in type 2 diabetes (T2D). However, the prevalence, plasticity and functional consequences of this cellular state remain unknown. METHODS We employed single-cell RNAseq to detail the maturation program of α- and β-cells during human ontogeny. We also compared islets from non-diabetic and T2D individuals. RESULTS Both α- and β-cells mature in part by repressing non-endocrine genes; however, α-cells retain hallmarks of an immature state, while β-cells attain a full β-cell specific gene expression program. In islets from T2D donors, both α- and β-cells have a less mature expression profile, de-repressing the juvenile genetic program and exocrine genes and increasing expression of exocytosis, inflammation and stress response signalling pathways. These changes are consistent with the increased proportion of β-cells displaying suboptimal function observed in T2D islets. CONCLUSIONS These findings provide new insights into the molecular program underlying islet cell maturation during human ontogeny and the loss of transcriptomic maturity that occurs in islets of type 2 diabetics.
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Affiliation(s)
- Dana Avrahami
- Endocrinology and Metabolism Department, Hadassah-Hebrew University Medical Centre, Jerusalem, Israel
| | - Yue J Wang
- Department of Genetics and Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Jonathan Schug
- Department of Genetics and Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Eseye Feleke
- Endocrinology and Metabolism Department, Hadassah-Hebrew University Medical Centre, Jerusalem, Israel
| | - Long Gao
- Department of Genetics and Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Chengyang Liu
- Department of Surgery and Institute for Diabetes, Obesity and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Ali Naji
- Department of Surgery and Institute for Diabetes, Obesity and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Benjamin Glaser
- Endocrinology and Metabolism Department, Hadassah-Hebrew University Medical Centre, Jerusalem, Israel.
| | - Klaus H Kaestner
- Department of Genetics and Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA.
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3
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Abstract
Glucose homeostasis is maintained in large part due to the actions of the pancreatic islet hormones insulin and glucagon, secreted from β- and α-cells, respectively. The historical narrative positions these hormones in opposition, with insulin primarily responsible for glucose-lowering and glucagon-driving elevations in glucose. Recent progress in this area has revealed a more complex relationship between insulin and glucagon, highlighted by data demonstrating that α-cell input is essential for β-cell function and glucose homeostasis. Moreover, the common perception that glucagon levels decrease following a nutrient challenge is largely shaped by the inhibitory effects of glucose administration alone on the α-cell. Largely overlooked is that a mixed nutrient challenge, which is more representative of typical human feeding, actually stimulates glucagon secretion. Thus, postprandial metabolism is associated with elevations, not decreases, in α-cell activity. This review discusses the recent advances in our understanding of how α-cells regulate metabolism, with a particular focus on the postprandial state. We highlight α- to β-cell communication, a term that describes how α-cell input into β-cells is a critical axis that regulates insulin secretion and glucose homeostasis. Finally, we discuss the open questions that have the potential to advance this field and continue to evolve our understanding of the role that α-cells play in postprandial metabolism.
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Affiliation(s)
- Kimberley El
- Duke Molecular Physiology Institute, Duke University, Durham, North Carolina
| | - Megan E Capozzi
- Duke Molecular Physiology Institute, Duke University, Durham, North Carolina
| | - Jonathan E Campbell
- Duke Molecular Physiology Institute, Duke University, Durham, North Carolina
- Department of Pharmacology and Cancer Biology, Duke University, Durham, North Carolina
- Department of Medicine, Division of Endocrinology, Duke University, Durham, North Carolina
- Correspondence: Jonathan E. Campbell, 300 N Duke Street, Durham, North Carolina 27701. E-mail:
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Miranda MA, Carson C, St. Pierre CL, Macias‐Velasco JF, Hughes JW, Kunzmann M, Schmidt H, Wayhart JP, Lawson HA. Spontaneous restoration of functional β-cell mass in obese SM/J mice. Physiol Rep 2020; 8:e14573. [PMID: 33113267 PMCID: PMC7592878 DOI: 10.14814/phy2.14573] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 08/08/2020] [Indexed: 12/23/2022] Open
Abstract
Maintenance of functional β-cell mass is critical to preventing diabetes, but the physiological mechanisms that cause β-cell populations to thrive or fail in the context of obesity are unknown. High fat-fed SM/J mice spontaneously transition from hyperglycemic-obese to normoglycemic-obese with age, providing a unique opportunity to study β-cell adaptation. Here, we characterize insulin homeostasis, islet morphology, and β-cell function during SM/J's diabetic remission. As they resolve hyperglycemia, obese SM/J mice dramatically increase circulating and pancreatic insulin levels while improving insulin sensitivity. Immunostaining of pancreatic sections reveals that obese SM/J mice selectively increase β-cell mass but not α-cell mass. Obese SM/J mice do not show elevated β-cell mitotic index, but rather elevated α-cell mitotic index. Functional assessment of isolated islets reveals that obese SM/J mice increase glucose-stimulated insulin secretion, decrease basal insulin secretion, and increase islet insulin content. These results establish that β-cell mass expansion and improved β-cell function underlie the resolution of hyperglycemia, indicating that obese SM/J mice are a valuable tool for exploring how functional β-cell mass can be recovered in the context of obesity.
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Affiliation(s)
- Mario A. Miranda
- Department of GeneticsWashington University School of MedicineSaint LouisMOUSA
| | - Caryn Carson
- Department of GeneticsWashington University School of MedicineSaint LouisMOUSA
| | | | | | - Jing W. Hughes
- Department of MedicineWashington University School of MedicineSaint LouisMOUSA
| | - Marcus Kunzmann
- Department of GeneticsWashington University School of MedicineSaint LouisMOUSA
| | - Heather Schmidt
- Department of GeneticsWashington University School of MedicineSaint LouisMOUSA
| | - Jessica P. Wayhart
- Department of GeneticsWashington University School of MedicineSaint LouisMOUSA
| | - Heather A. Lawson
- Department of GeneticsWashington University School of MedicineSaint LouisMOUSA
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Rubey M, Chhabra NF, Gradinger D, Sanz-Moreno A, Lickert H, Przemeck GKH, Hrabě de Angelis M. DLL1- and DLL4-Mediated Notch Signaling Is Essential for Adult Pancreatic Islet Homeostasis. Diabetes 2020; 69:915-926. [PMID: 32029480 DOI: 10.2337/db19-0795] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 01/22/2020] [Indexed: 11/13/2022]
Abstract
Genes of the Notch signaling pathway are expressed in different cell types and organs at different time points during embryonic development and adulthood. The Notch ligand Delta-like 1 (DLL1) controls the decision between endocrine and exocrine fates of multipotent progenitors in the developing pancreas, and loss of Dll1 leads to premature endocrine differentiation. However, the role of Delta-Notch signaling in adult tissue homeostasis is not well understood. Here, we describe the spatial expression pattern of Notch pathway components in adult murine pancreatic islets and show that DLL1 and DLL4 are specifically expressed in β-cells, whereas JAGGED1 is expressed in α-cells. We show that mice lacking both DLL1 and DLL4 in adult β-cells display improved glucose tolerance, increased glucose-stimulated insulin secretion, and hyperglucagonemia. In contrast, overexpression of the intracellular domain of DLL1 in adult murine pancreatic β-cells results in impaired glucose tolerance and reduced insulin secretion, both in vitro and in vivo. These results suggest that Notch ligands play specific roles in the adult pancreas and highlight a novel function of the Delta/Notch pathway in β-cell insulin secretion.
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Affiliation(s)
- Marina Rubey
- Institute of Experimental Genetics and German Mouse Clinic, Helmholtz Zentrum München, Neuherberg, Germany
- German Center for Diabetes Research, Neuherberg, Germany
| | - Nirav Florian Chhabra
- Institute of Experimental Genetics and German Mouse Clinic, Helmholtz Zentrum München, Neuherberg, Germany
- German Center for Diabetes Research, Neuherberg, Germany
| | - Daniel Gradinger
- Institute of Experimental Genetics and German Mouse Clinic, Helmholtz Zentrum München, Neuherberg, Germany
- German Center for Diabetes Research, Neuherberg, Germany
| | - Adrián Sanz-Moreno
- Institute of Experimental Genetics and German Mouse Clinic, Helmholtz Zentrum München, Neuherberg, Germany
| | - Heiko Lickert
- German Center for Diabetes Research, Neuherberg, Germany
- Institute of Diabetes and Regeneration Research and Institute of Stem Cell Research, Helmholtz Zentrum München, Neuherberg, Germany
- Medical Faculty, Technische Universität München, Munich, Germany
| | - Gerhard K H Przemeck
- Institute of Experimental Genetics and German Mouse Clinic, Helmholtz Zentrum München, Neuherberg, Germany
- German Center for Diabetes Research, Neuherberg, Germany
| | - Martin Hrabě de Angelis
- Institute of Experimental Genetics and German Mouse Clinic, Helmholtz Zentrum München, Neuherberg, Germany
- German Center for Diabetes Research, Neuherberg, Germany
- Centre of Life and Food Sciences, Weihenstephan, Technische Universität München, Freising, Germany
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Zhao L, Wang L, Aierken R, Wang W, Wang X, Li M. Characterization of Insulin and Glucagon Genes and Their Producing Endocrine Cells From Pygmy Sperm Whale ( Kogia breviceps). Front Endocrinol (Lausanne) 2020; 11:174. [PMID: 32296396 PMCID: PMC7137828 DOI: 10.3389/fendo.2020.00174] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 03/11/2020] [Indexed: 02/05/2023] Open
Abstract
Insulin and glucagon are hormones secreted by pancreatic β and α cells, respectively, which together regulate glucose homeostasis. Dysregulation of insulin or glucagon can result in loss of blood glucose control, characterized by hyperglycemia or hypoglycemia. To better understand the endocrine physiology of cetaceans, we cloned and characterized the insulin and glucagon genes from pygmy sperm whale (Kogia breviceps). We obtained the complete coding sequences of the preproinsulin and preproglucagon genes, which encodes the preproinsulin protein of 110 amino acid (aa) residues and encodes the preproglucagon protein of 179 aa residues, respectively. Sequence comparison and phylogenetic analyses demonstrate that protein structures were similar to other mammalian orthologs. Immunohistochemistry and immunofluorescence staining using insulin, glucagon, and somatostatin antibodies allowed analysis of pygmy sperm whale islet distribution, architecture, and composition. Our results showed the pygmy sperm whale islet was irregularly shaped and randomly distributed throughout the pancreas. The architecture of α, β, and δ cells of the pygmy sperm whale was similar to that of artiodactyls species. This is the first report about insulin and glucagon genes in cetaceans, which provides new information about the structural conservation of the insulin and glucagon genes. Furthermore, offers novel information on the properties of endocrine cells in cetacean for further studies.
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Affiliation(s)
- Liyuan Zhao
- Laboratory of Marine Biology and Ecology, Fujian Provincial Key Laboratory of Marine Ecological Conservation and Restoration, Third Institute of Oceanography, Ministry of Natural Resources, Xiamen, China
| | - Likun Wang
- School of Pharmaceutical Sciences, Fujian Provincial Key Laboratory of Innovative Drug Target Research, Xiamen University, Xiamen, China
- Department of Endocrinology, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
| | - Reyilamu Aierken
- Laboratory of Marine Biology and Ecology, Fujian Provincial Key Laboratory of Marine Ecological Conservation and Restoration, Third Institute of Oceanography, Ministry of Natural Resources, Xiamen, China
| | - Wei Wang
- Department of Endocrinology, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
| | - Xianyan Wang
- Laboratory of Marine Biology and Ecology, Fujian Provincial Key Laboratory of Marine Ecological Conservation and Restoration, Third Institute of Oceanography, Ministry of Natural Resources, Xiamen, China
- *Correspondence: Xianyan Wang
| | - Mingyu Li
- School of Pharmaceutical Sciences, Fujian Provincial Key Laboratory of Innovative Drug Target Research, Xiamen University, Xiamen, China
- Mingyu Li
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8
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Quesada-Candela C, Tudurí E, Marroquí L, Alonso-Magdalena P, Quesada I, Nadal Á. Morphological and functional adaptations of pancreatic alpha-cells during late pregnancy in the mouse. Metabolism 2020; 102:153963. [PMID: 31593706 DOI: 10.1016/j.metabol.2019.153963] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Revised: 08/01/2019] [Accepted: 08/26/2019] [Indexed: 01/18/2023]
Abstract
BACKGROUND Pregnancy represents a major metabolic challenge for the mother, and involves a compensatory response of the pancreatic beta-cell to maintain normoglycemia. However, although pancreatic alpha-cells play a key role in glucose homeostasis and seem to be involved in gestational diabetes, there is no information about their potential adaptations or changes during pregnancy. MATERIAL AND METHODS Non-pregnant (controls) and pregnant C57BL/6 mice at gestational day 18.5 (G18.5) and their isolated pancreatic islets were used for in vivo and ex vivo studies, respectively. The effect of pregnancy hormones was tested in glucagon-secreting α-TC1.9 cells. Immunohistochemical analysis was performed in pancreatic slices. Glucagon gene expression was monitored by RT-qPCR. Glucagon secretion and plasma hormones were measured by ELISA. RESULTS Pregnant mice on G18.5 exhibited alpha-cell hypertrophy as well as augmented alpha-cell area and mass. This alpha-cell mass expansion was mainly due to increased proliferation. No changes in alpha-cell apoptosis, ductal neogenesis, or alpha-to-beta transdifferentiation were found compared with controls. Pregnant mice on G18.5 exhibited hypoglucagonemia. Additionally, in vitro glucagon secretion at low glucose levels was decreased in isolated islets from pregnant animals. Glucagon content was also reduced. Experiments in α-TC1.9 cells indicated that, unlike estradiol and progesterone, placental lactogens and prolactin stimulated alpha-cell proliferation. Placental lactogens, prolactin and estradiol also inhibited glucagon release from α-TC1.9 cells at low glucose levels. CONCLUSIONS The pancreatic alpha-cell in mice undergoes several morphofunctional changes during late pregnancy, which may contribute to proper glucose homeostasis. Gestational hormones are likely involved in these processes.
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Affiliation(s)
- Cristina Quesada-Candela
- Instituto de Biología Molecular y Celular (IBMC), Universitas Miguel Hernández, 03202 Elche, Spain; Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDiBE), Universitas Miguel Hernández, 03202 Elche, Spain; Spanish Biomedical Research Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM), Spain
| | - Eva Tudurí
- Instituto de Biología Molecular y Celular (IBMC), Universitas Miguel Hernández, 03202 Elche, Spain; Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDiBE), Universitas Miguel Hernández, 03202 Elche, Spain; Spanish Biomedical Research Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM), Spain
| | - Laura Marroquí
- Instituto de Biología Molecular y Celular (IBMC), Universitas Miguel Hernández, 03202 Elche, Spain; Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDiBE), Universitas Miguel Hernández, 03202 Elche, Spain; Spanish Biomedical Research Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM), Spain
| | - Paloma Alonso-Magdalena
- Instituto de Biología Molecular y Celular (IBMC), Universitas Miguel Hernández, 03202 Elche, Spain; Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDiBE), Universitas Miguel Hernández, 03202 Elche, Spain; Spanish Biomedical Research Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM), Spain
| | - Ivan Quesada
- Instituto de Biología Molecular y Celular (IBMC), Universitas Miguel Hernández, 03202 Elche, Spain; Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDiBE), Universitas Miguel Hernández, 03202 Elche, Spain; Spanish Biomedical Research Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM), Spain.
| | - Ángel Nadal
- Instituto de Biología Molecular y Celular (IBMC), Universitas Miguel Hernández, 03202 Elche, Spain; Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDiBE), Universitas Miguel Hernández, 03202 Elche, Spain; Spanish Biomedical Research Centre in Diabetes and Associated Metabolic Disorders (CIBERDEM), Spain.
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9
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Abstract
Diabetes mellitus is a multifactorial disease affecting increasing numbers of patients worldwide. Progression to insulin-dependent diabetes mellitus is characterized by the loss or dysfunction of pancreatic β-cells, but the pathomechanisms underlying β-cell failure in type 1 diabetes mellitus and type 2 diabetes mellitus are still poorly defined. Regeneration of β-cell mass from residual islet cells or replacement by β-like cells derived from stem cells holds great promise to stop or reverse disease progression. However, the development of new treatment options is hampered by our limited understanding of human pancreas organogenesis due to the restricted access to primary tissues. Therefore, the challenge is to translate results obtained from preclinical model systems to humans, which requires comparative modelling of β-cell biology in health and disease. Here, we discuss diverse modelling systems across different species that provide spatial and temporal resolution of cellular and molecular mechanisms to understand the evolutionary conserved genotype-phenotype relationship and translate them to humans. In addition, we summarize the latest knowledge on organoids, stem cell differentiation platforms, primary micro-islets and pseudo-islets, bioengineering and microfluidic systems for studying human pancreas development and homeostasis ex vivo. These new modelling systems and platforms have opened novel avenues for exploring the developmental trajectory, physiology, biology and pathology of the human pancreas.
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Affiliation(s)
- Mostafa Bakhti
- Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, Neuherberg, Germany.
- Institute of Stem Cell Research, Helmholtz Zentrum München, Neuherberg, Germany.
- German Center for Diabetes Research (DZD), Neuherberg, Germany.
| | - Anika Böttcher
- Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, Neuherberg, Germany.
- Institute of Stem Cell Research, Helmholtz Zentrum München, Neuherberg, Germany.
- German Center for Diabetes Research (DZD), Neuherberg, Germany.
| | - Heiko Lickert
- Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, Neuherberg, Germany.
- Institute of Stem Cell Research, Helmholtz Zentrum München, Neuherberg, Germany.
- German Center for Diabetes Research (DZD), Neuherberg, Germany.
- Technical University of Munich, Medical Faculty, Munich, Germany.
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Zhang W, Wang L, Yu X, Jia A, Ming J, Ji Q. RFamide-related peptide-3 promotes alpha TC1 clone 6 cell survival likely via GPR147. Peptides 2018; 107:39-44. [PMID: 30081043 DOI: 10.1016/j.peptides.2018.07.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 07/08/2018] [Accepted: 07/31/2018] [Indexed: 12/19/2022]
Abstract
Type 2 diabetes mellitus (T2DM) is closely related to islet alpha cell mass and viability. Several types of RFamide-related peptides (RFRPs) are involved in regulating proliferation and function of islet cells. However, current understanding of the role of RFamide-related peptide-3 (RFRP-3) in pancreatic alpha cells is limited. Therefore, we investigated the expression of the RFRP-3 receptor, G protein-coupled receptor 147 (GPR147), in mouse islets and alpha TC1 clone 6 cells, and evaluated the function of RFRP-3 on alpha cells. We show that GPR147 is expressed in mouse islets and alpha cell lines. In addition, RFRP-3 promotes survival of alpha cells under conditions of hyperglycemia and serum starvation. Mechanistic evidence demonstrates that RFRP-3 activated PI3K/AKT and ERK1/2 signaling cascades and treatment with an antagonist of GPR147, 1-adamantanecarbonyl-Arg-Phe-NH₂ (RF9) blocked this function. These findings indicate a novel effect of RFRP-3 in promoting alpha cell survival, likely via GPR147.
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Affiliation(s)
- Wencheng Zhang
- Department of Endocrinology, Xijing Hospital, Fourth Military Medical University, Xi'an, 169 Changle Road West, 710032, China
| | - Li Wang
- Department of Endocrinology, Xijing Hospital, Fourth Military Medical University, Xi'an, 169 Changle Road West, 710032, China
| | - Xinwen Yu
- Department of Endocrinology, Xijing Hospital, Fourth Military Medical University, Xi'an, 169 Changle Road West, 710032, China
| | - Aihua Jia
- Department of Endocrinology, Xijing Hospital, Fourth Military Medical University, Xi'an, 169 Changle Road West, 710032, China
| | - Jie Ming
- Department of Endocrinology, Xijing Hospital, Fourth Military Medical University, Xi'an, 169 Changle Road West, 710032, China
| | - Qiuhe Ji
- Department of Endocrinology, Xijing Hospital, Fourth Military Medical University, Xi'an, 169 Changle Road West, 710032, China.
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Esguerra JLS, Nagao M, Ofori JK, Wendt A, Eliasson L. MicroRNAs in islet hormone secretion. Diabetes Obes Metab 2018; 20 Suppl 2:11-19. [PMID: 30230181 DOI: 10.1111/dom.13382] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 05/10/2018] [Accepted: 05/23/2018] [Indexed: 12/12/2022]
Abstract
Pancreatic islet hormone secretion is central in the maintenance of blood glucose homeostasis. During development of hyperglycaemia, the β-cell is under pressure to release more insulin to compensate for increased insulin resistance. Failure of the β-cells to secrete enough insulin results in type 2 diabetes (T2D). MicroRNAs (miRNAs) are short non-coding RNA molecules suitable for rapid regulation of the changes in target gene expression needed in β-cell adaptations. Moreover, miRNAs are involved in the maintenance of α-cell and β-cell phenotypic identities via cell-specific, or cell-enriched expression. Although many of the abundant miRNAs are highly expressed in both cell types, recent research has focused on the role of miRNAs in β-cells. It has been shown that highly abundant miRNAs, such as miR-375, are involved in several cellular functions indispensable in maintaining β-cell phenotypic identity, almost acting as "housekeeping genes" in the context of hormone secretion. Despite the abundance and importance of miR-375, it has not been shown to be differentially expressed in T2D islets. On the contrary, the less abundant miRNAs such as miR-212/miR-132, miR-335, miR-130a/b and miR-152 are deregulated in T2D islets, wherein the latter three miRNAs were shown to play key roles in regulating β-cell metabolism. In this review, we focus on β-cell function and describe miRNAs involved in insulin biosynthesis and processing, glucose uptake and metabolism, electrical activity and Ca2+ -influx and exocytosis of the insulin granules. We present current status on miRNA regulation in α-cells, and finally we discuss the involvement of miRNAs in β-cell dysfunction underlying T2D pathogenesis.
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Affiliation(s)
- Jonathan L S Esguerra
- Islet Cell Exocytosis, Lund University Diabetes Centre, Department of Clinical Sciences Malmö, Lund University, Clinical Research Centre, SUS, Malmö, Sweden
| | - Mototsugu Nagao
- Islet Cell Exocytosis, Lund University Diabetes Centre, Department of Clinical Sciences Malmö, Lund University, Clinical Research Centre, SUS, Malmö, Sweden
| | - Jones K Ofori
- Islet Cell Exocytosis, Lund University Diabetes Centre, Department of Clinical Sciences Malmö, Lund University, Clinical Research Centre, SUS, Malmö, Sweden
| | - Anna Wendt
- Islet Cell Exocytosis, Lund University Diabetes Centre, Department of Clinical Sciences Malmö, Lund University, Clinical Research Centre, SUS, Malmö, Sweden
| | - Lena Eliasson
- Islet Cell Exocytosis, Lund University Diabetes Centre, Department of Clinical Sciences Malmö, Lund University, Clinical Research Centre, SUS, Malmö, Sweden
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12
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Ramracheya R, Chapman C, Chibalina M, Dou H, Miranda C, González A, Moritoh Y, Shigeto M, Zhang Q, Braun M, Clark A, Johnson PR, Rorsman P, Briant LJB. GLP-1 suppresses glucagon secretion in human pancreatic alpha-cells by inhibition of P/Q-type Ca 2+ channels. Physiol Rep 2018; 6:e13852. [PMID: 30187652 PMCID: PMC6125244 DOI: 10.14814/phy2.13852] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 07/31/2018] [Accepted: 08/07/2018] [Indexed: 01/13/2023] Open
Abstract
Glucagon is the body's main hyperglycemic hormone, and its secretion is dysregulated in type 2 diabetes mellitus (T2DM). The incretin hormone glucagon-like peptide-1 (GLP-1) is released from the gut and is used in T2DM therapy. Uniquely, it both stimulates insulin and inhibits glucagon secretion and thereby lowers plasma glucose levels. In this study, we have investigated the action of GLP-1 on glucagon release from human pancreatic islets. Immunocytochemistry revealed that only <0.5% of the α-cells possess detectable GLP-1R immunoreactivity. Despite this, GLP-1 inhibited glucagon secretion by 50-70%. This was due to a direct effect on α-cells, rather than paracrine signaling, because the inhibition was not reversed by the insulin receptor antagonist S961 or the somatostatin receptor-2 antagonist CYN154806. The inhibitory effect of GLP-1 on glucagon secretion was prevented by the PKA-inhibitor Rp-cAMPS and mimicked by the adenylate cyclase activator forskolin. Electrophysiological measurements revealed that GLP-1 decreased action potential height and depolarized interspike membrane potential. Mathematical modeling suggests both effects could result from inhibition of P/Q-type Ca2+ channels. In agreement with this, GLP-1 and ω-agatoxin (a blocker of P/Q-type channels) inhibited glucagon secretion in islets depolarized by 70 mmol/L [K+ ]o , and these effects were not additive. Intracellular application of cAMP inhibited depolarization-evoked exocytosis in individual α-cells by a PKA-dependent (Rp-cAMPS-sensitive) mechanism. We propose that inhibition of glucagon secretion by GLP-1 involves activation of the few GLP-1 receptors present in the α-cell membrane. The resulting small elevation of cAMP leads to PKA-dependent inhibition of P/Q-type Ca2+ channels and suppression of glucagon exocytosis.
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Affiliation(s)
- Reshma Ramracheya
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of MedicineUniversity of OxfordOxfordUnited Kingdom
| | - Caroline Chapman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of MedicineUniversity of OxfordOxfordUnited Kingdom
| | - Margarita Chibalina
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of MedicineUniversity of OxfordOxfordUnited Kingdom
| | - Haiqiang Dou
- Institute of Neuroscience and PhysiologyMetabolic Research UnitUniversity of GöteborgGöteborgSweden
| | - Caroline Miranda
- Institute of Neuroscience and PhysiologyMetabolic Research UnitUniversity of GöteborgGöteborgSweden
| | - Alejandro González
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of MedicineUniversity of OxfordOxfordUnited Kingdom
| | - Yusuke Moritoh
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of MedicineUniversity of OxfordOxfordUnited Kingdom
| | - Makoto Shigeto
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of MedicineUniversity of OxfordOxfordUnited Kingdom
| | - Quan Zhang
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of MedicineUniversity of OxfordOxfordUnited Kingdom
| | - Matthias Braun
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of MedicineUniversity of OxfordOxfordUnited Kingdom
| | - Anne Clark
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of MedicineUniversity of OxfordOxfordUnited Kingdom
| | - Paul R. Johnson
- Nuffield Department of SurgeryUniversity of OxfordJohn Radcliffe HospitalOxfordUnited Kingdom
- NIHR Oxford Biomedical Research CentreOxfordUnited Kingdom
| | - Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of MedicineUniversity of OxfordOxfordUnited Kingdom
- Institute of Neuroscience and PhysiologyMetabolic Research UnitUniversity of GöteborgGöteborgSweden
- NIHR Oxford Biomedical Research CentreOxfordUnited Kingdom
| | - Linford J. B. Briant
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of MedicineUniversity of OxfordOxfordUnited Kingdom
- Department of Computer ScienceUniversity of OxfordOxfordUnited Kingdom
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Abstract
Hyperglucagonaemia (in the fasting as well as in the postprandial state) is considered a core pathophysiological component of diabetes and is found to contribute substantially to the hyperglycaemic state of diabetes. Hyperglucagonaemia is usually viewed upon as a consequence of pancreatic alpha cell insensitivity to the glucagon-suppressive effects of glucose and insulin. Since we observed that the well-known hyperglucagonaemic response to oral glucose in patients with type 2 diabetes is exchanged by normal suppression of plasma glucagon levels following isoglycaemic intravenous glucose administration in these patients, we have been focusing on the gut and gut-derived factors as potential mediators of diabetic hyperglucagonaemia. In a series of clinical experiments, we have elucidated the role of gut-derived factors in diabetic hyperglucagonaemia and shown that glucose-dependent insulinotropic polypeptide promotes hyperglucagonaemia and that glucagon, hitherto considered a pancreas-specific hormone, may also be secreted from extrapancreatic tissues - most likely from proglucagon-producing enteroendocrine cells. Furthermore, our observation that fasting hyperglucagonaemia is unrelated to the diabetic state, but strongly correlates with obesity, liver fat content and circulating amino acids, has made us question the common 'pancreacentric' and 'glucocentric' understanding of hyperglucagonaemia and led to the hypothesis that steatosis-induced hepatic glucagon resistance (and reduced amino acid turnover) and compensatory glucagon secretion mediated by increased circulating amino acids constitute a complete endocrine feedback system: the liver-alpha cell axis. This article summarises the physiological regulation of glucagon secretion in humans and considers new findings suggesting that the liver and the gut play key roles in determining fasting and postabsorptive circulating glucagon levels.
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Affiliation(s)
- Filip K Knop
- Clinical Metabolic PhysiologySteno Diabetes Center Copenhagen, Gentofte Hospital, University of Copenhagen, Hellerup, Denmark
- Department of Clinical Medicine Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic ResearchFaculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Galsgaard KD, Winther-Sørensen M, Ørskov C, Kissow H, Poulsen SS, Vilstrup H, Prehn C, Adamski J, Jepsen SL, Hartmann B, Hunt J, Charron MJ, Pedersen J, Wewer Albrechtsen NJ, Holst JJ. Disruption of glucagon receptor signaling causes hyperaminoacidemia exposing a possible liver-alpha-cell axis. Am J Physiol Endocrinol Metab 2018; 314:E93-E103. [PMID: 28978545 PMCID: PMC6048389 DOI: 10.1152/ajpendo.00198.2017] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Glucagon secreted from the pancreatic alpha-cells is essential for regulation of blood glucose levels. However, glucagon may play an equally important role in the regulation of amino acid metabolism by promoting ureagenesis. We hypothesized that disruption of glucagon receptor signaling would lead to an increased plasma concentration of amino acids, which in a feedback manner stimulates the secretion of glucagon, eventually associated with compensatory proliferation of the pancreatic alpha-cells. To address this, we performed plasma profiling of glucagon receptor knockout ( Gcgr-/-) mice and wild-type (WT) littermates using liquid chromatography-mass spectrometry (LC-MS)-based metabolomics, and tissue biopsies from the pancreas were analyzed for islet hormones and by histology. A principal component analysis of the plasma metabolome from Gcgr-/- and WT littermates indicated amino acids as the primary metabolic component distinguishing the two groups of mice. Apart from their hyperaminoacidemia, Gcgr-/- mice display hyperglucagonemia, increased pancreatic content of glucagon and somatostatin (but not insulin), and alpha-cell hyperplasia and hypertrophy compared with WT littermates. Incubating cultured α-TC1.9 cells with a mixture of amino acids (Vamin 1%) for 30 min and for up to 48 h led to increased glucagon concentrations (~6-fold) in the media and cell proliferation (~2-fold), respectively. In anesthetized mice, a glucagon receptor-specific antagonist (Novo Nordisk 25-2648, 100 mg/kg) reduced amino acid clearance. Our data support the notion that glucagon secretion and hepatic amino acid metabolism are linked in a close feedback loop, which operates independently of normal variations in glucose metabolism.
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Affiliation(s)
- Katrine D Galsgaard
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
| | - Marie Winther-Sørensen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
| | - Cathrine Ørskov
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
| | - Hannelouise Kissow
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
| | - Steen S Poulsen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
| | - Hendrik Vilstrup
- Department of Hepato-Gastroenterology, Aarhus University Hospital , Aarhus , Denmark
| | - Cornelia Prehn
- Institute of Experimental Genetics, Genome Analysis Center, Helmholtz Zentrum, German Research Center for Environmental Health, München-Neuerberg, Germany
| | - Jerzy Adamski
- Institute of Experimental Genetics, Genome Analysis Center, Helmholtz Zentrum, German Research Center for Environmental Health, München-Neuerberg, Germany
- Lehrstul für Experimentelle Genetik, Technishe Universität München, Freising- Weihenstephan , Germany
- German Center for Diabetes Research, München-Nueherberg, Germany
| | - Sara L Jepsen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
| | - Bolette Hartmann
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
| | - Jenna Hunt
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
| | - Maureen J Charron
- Departments of Biochemistry, Obstetrics and Gynecology and Women's Health, and Medicine, Albert Einstein College of Medicine , New York, New York
| | - Jens Pedersen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
| | - Nicolai J Wewer Albrechtsen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
| | - Jens J Holst
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark
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Huang WQ, Guo JH, Zhang XH, Yu MK, Chung YW, Ruan YC, Chan HC. Glucose-Sensitive CFTR Suppresses Glucagon Secretion by Potentiating KATP Channels in Pancreatic Islet α Cells. Endocrinology 2017; 158:3188-3199. [PMID: 28977595 DOI: 10.1210/en.2017-00282] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 07/18/2017] [Indexed: 12/14/2022]
Abstract
The secretion of glucagon by islet α cells is normally suppressed by high blood glucose, but this suppressibility is impaired in patients with diabetes or cystic fibrosis (CF), a disease caused by mutations in the gene encoding CF transmembrane conductance regulator (CFTR), a cyclic adenosine monophosphate-activated Cl- channel. However, precisely how glucose regulates glucagon release remains controversial. Here we report that elevated glucagon secretion, together with increased glucose-induced membrane depolarization and Ca2+ response, is found in CFTR mutant (DF508) mice/islets compared with the wild-type. Overexpression of CFTR in AlphaTC1-9 cells results in membrane hyperpolarization and reduced glucagon release, which can be reversed by CFTR inhibition. CFTR is found to potentiate the adenosine triphosphate-sensitive K+ (KATP) channel because membrane depolarization and whole-cell currents sensitive to KATP blockers are significantly greater in wild-type/CFTR-overexpressed α cells compared with that in DF508/non-overexpressed cells. KATP knockdown also reverses the suppressive effect of CFTR overexpression on glucagon secretion. The results reveal that by potentiating KATP channels, CFTR acts as a glucose-sensing negative regulator of glucagon secretion in α cells, a defect of which may contribute to glucose intolerance in CF and other types of diabetes.
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Affiliation(s)
- Wen Qing Huang
- Epithelial Cell Biology Research Center, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong
| | - Jing Hui Guo
- Epithelial Cell Biology Research Center, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong
- Department of Pathophysiology, Key Laboratory of State Administration of Traditional Chinese Medicine of the People's Republic of China, School of Medicine, Jinan University, Guangzhou 510632, People's Republic of China
| | - Xiao Hu Zhang
- Epithelial Cell Biology Research Center, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong
- Sichuan University-The Chinese University of Hong Kong Joint Laboratory for Reproductive Medicine, Key Laboratory of Obstetric, Gynecologic and Pediatric Diseases and Birth Defects of Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu 610041, People's Republic of China
| | - Mei Kuen Yu
- Epithelial Cell Biology Research Center, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong
| | - Yiu Wa Chung
- Epithelial Cell Biology Research Center, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong
| | - Ye Chun Ruan
- Epithelial Cell Biology Research Center, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong
- Interdisciplinary Division of Biomedical Engineering, the Hong Kong Polytechnic University, Hong Kong, Hong Kong
| | - Hsiao Chang Chan
- Epithelial Cell Biology Research Center, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong
- Sichuan University-The Chinese University of Hong Kong Joint Laboratory for Reproductive Medicine, Key Laboratory of Obstetric, Gynecologic and Pediatric Diseases and Birth Defects of Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu 610041, People's Republic of China
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16
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Abstract
PURPOSE Glucagon-like peptide-1 (GLP-1) is originally identified in the gut as an incretin hormone, and it is potent in stimulating insulin secretion in the pancreas. However, increasing evidence suggests that GLP-1 is also produced locally within pancreatic islets. This review focuses on the past and current discoveries regarding intra-islet GLP-1 production and its functions. MAIN FINDINGS There has been a long-standing debate with regard to whether GLP-1 is produced in the pancreatic α cells. Early controversies lead to the widely accepted conclusion that the vast majority of proglucagon is processed to form glucagon in the pancreas, whereas an insignificant amount is cleaved to produce GLP-1. With technological advancements, recent studies have shown that bioactive GLP-1 is produced locally in the pancreas, and the expression and secretion of GLP-1 within islets are regulated by various factors such as cytokines, hyperglycemia, and β cell injury. CONCLUSIONS GLP-1 is produced by the pancreatic α cells, and it is fully functional as an incretin. Therefore, intra-islet GLP-1 may exert insulinotropic and glucagonostatic effects locally via paracrine and/or autocrine actions, under both normal and diabetic conditions.
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Affiliation(s)
- Genevieve E Fava
- Endocrinology Section, Department of Medicine, Tulane University Health Science Center, New Orleans, LA, United States
| | - Emily W Dong
- Endocrinology Section, Department of Medicine, Tulane University Health Science Center, New Orleans, LA, United States
| | - Hongju Wu
- Endocrinology Section, Department of Medicine, Tulane University Health Science Center, New Orleans, LA, United States.
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17
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Nielsen SS, Christensen GL, Holst JJ, Billestrup N. Regulation of Pancreatic α-Cell Function and Proliferation by Bone Morphogenetic Protein 4 (BMP4) In Vitro. Endocrinology 2016; 157:3809-3820. [PMID: 27479530 DOI: 10.1210/en.2016-1163] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Increased expression of bone morphogenetic proteins (BMPs) in several tissues is associated with inflammation and type 2 diabetes mellitus. BMP2 and BMP4 mRNA expression is increased in pancreatic islets from db/db mice and β-cell proliferation and function are inhibited by BMP4. The effect of BMPs on α-cells is currently unknown. Here, we investigate the effects of BMP4 on mouse and human α-cells in vitro. The effects of BMP4 on α-cell proliferation and function were investigated in islets isolated from male mice and from human donors, and in α-TC1-6 cells. The effects of BMP4 on α-cell function were assessed by determination of glucagon secretion and gene expression. Treatment with BMP4 for 24-96 hours inhibited glucagon secretion in a time-dependent manner in mouse and human islets. Glucagon content, preproglucagon and aristaless related homeobox mRNA expression were reduced after incubation with BMP4 in mouse islets, but not in human islets. The percentage of proliferating α-cells was reduced from 7.3 % to 0.2 % in mouse islets incubated with BMP4. α-cell proliferation in human islets ranged from 0 to 11.8 %, and BMP4 was found to inhibit proliferation of α-cells from all donors when proliferation was present. In agreement with the observations in primary islets, BMP4 decreased glucagon content, preproglucagon, and aristaless related homeobox mRNA expression in α-TC1-6 cells. Our findings suggest that BMP4 has an inhibitory role on glucagon secretion, α-cell growth, and expression of genes maintaining α-cell identity.
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Affiliation(s)
- Sofie Sylvest Nielsen
- Department of Biomedical Sciences, University of Copenhagen, 2200 Copenhagen N, Denmark
| | | | - Jens Juul Holst
- Department of Biomedical Sciences, University of Copenhagen, 2200 Copenhagen N, Denmark
| | - Nils Billestrup
- Department of Biomedical Sciences, University of Copenhagen, 2200 Copenhagen N, Denmark
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18
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Cinti F, Bouchi R, Kim-Muller JY, Ohmura Y, Sandoval PR, Masini M, Marselli L, Suleiman M, Ratner LE, Marchetti P, Accili D. Evidence of β-Cell Dedifferentiation in Human Type 2 Diabetes. J Clin Endocrinol Metab 2016; 101:1044-54. [PMID: 26713822 PMCID: PMC4803182 DOI: 10.1210/jc.2015-2860] [Citation(s) in RCA: 368] [Impact Index Per Article: 46.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
CONTEXT Diabetes is associated with a deficit of insulin-producing β-cells. Animal studies show that β-cells become dedifferentiated in diabetes, reverting to a progenitor-like stage, and partly converting to other endocrine cell types. OBJECTIVE To determine whether similar processes occur in human type 2 diabetes, we surveyed pancreatic islets from 15 diabetic and 15 nondiabetic organ donors. DESIGN We scored dedifferentiation using markers of endocrine lineage, β-cell-specific transcription factors, and a newly identified endocrine progenitor cell marker, aldehyde dehydrogenase 1A3. RESULTS By these criteria, dedifferentiated cells accounted for 31.9% of β-cells in type 2 diabetics vs 8.7% in controls, and for 16.8% vs 6.5% of all endocrine cells (P < .001). The number of aldehyde dehydrogenase 1A3-positive/hormone-negative cells was 3-fold higher in diabetics compared with controls. Moreover, β-cell-specific transcription factors were ectopically found in glucagon- and somatostatin-producing cells of diabetic subjects. CONCLUSIONS The data support the view that pancreatic β-cells become dedifferentiated and convert to α- and δ-"like" cells in human type 2 diabetes. The findings should prompt a reassessment of goals in the prevention and treatment of β-cell dysfunction.
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Affiliation(s)
- Francesca Cinti
- Departments of Medicine (F.C., R.B., J.Y.K.-M., D.A.) and Surgery (Y.O., P.R.S., L.E.R.), Columbia University College of Physicians and Surgeons, New York, New York 10032; Department of Clinical and Experimental Medicine (F.C.), Università Politecnica delle Marche, Ancona, Italy; and Department of Clinical and Experimental Medicine (M.M., L.M., M.S., P.M.), Islet Cell Laboratory, University of Pisa, 56100 Pisa, Italy
| | - Ryotaro Bouchi
- Departments of Medicine (F.C., R.B., J.Y.K.-M., D.A.) and Surgery (Y.O., P.R.S., L.E.R.), Columbia University College of Physicians and Surgeons, New York, New York 10032; Department of Clinical and Experimental Medicine (F.C.), Università Politecnica delle Marche, Ancona, Italy; and Department of Clinical and Experimental Medicine (M.M., L.M., M.S., P.M.), Islet Cell Laboratory, University of Pisa, 56100 Pisa, Italy
| | - Ja Young Kim-Muller
- Departments of Medicine (F.C., R.B., J.Y.K.-M., D.A.) and Surgery (Y.O., P.R.S., L.E.R.), Columbia University College of Physicians and Surgeons, New York, New York 10032; Department of Clinical and Experimental Medicine (F.C.), Università Politecnica delle Marche, Ancona, Italy; and Department of Clinical and Experimental Medicine (M.M., L.M., M.S., P.M.), Islet Cell Laboratory, University of Pisa, 56100 Pisa, Italy
| | - Yoshiaki Ohmura
- Departments of Medicine (F.C., R.B., J.Y.K.-M., D.A.) and Surgery (Y.O., P.R.S., L.E.R.), Columbia University College of Physicians and Surgeons, New York, New York 10032; Department of Clinical and Experimental Medicine (F.C.), Università Politecnica delle Marche, Ancona, Italy; and Department of Clinical and Experimental Medicine (M.M., L.M., M.S., P.M.), Islet Cell Laboratory, University of Pisa, 56100 Pisa, Italy
| | - P R Sandoval
- Departments of Medicine (F.C., R.B., J.Y.K.-M., D.A.) and Surgery (Y.O., P.R.S., L.E.R.), Columbia University College of Physicians and Surgeons, New York, New York 10032; Department of Clinical and Experimental Medicine (F.C.), Università Politecnica delle Marche, Ancona, Italy; and Department of Clinical and Experimental Medicine (M.M., L.M., M.S., P.M.), Islet Cell Laboratory, University of Pisa, 56100 Pisa, Italy
| | - Matilde Masini
- Departments of Medicine (F.C., R.B., J.Y.K.-M., D.A.) and Surgery (Y.O., P.R.S., L.E.R.), Columbia University College of Physicians and Surgeons, New York, New York 10032; Department of Clinical and Experimental Medicine (F.C.), Università Politecnica delle Marche, Ancona, Italy; and Department of Clinical and Experimental Medicine (M.M., L.M., M.S., P.M.), Islet Cell Laboratory, University of Pisa, 56100 Pisa, Italy
| | - Lorella Marselli
- Departments of Medicine (F.C., R.B., J.Y.K.-M., D.A.) and Surgery (Y.O., P.R.S., L.E.R.), Columbia University College of Physicians and Surgeons, New York, New York 10032; Department of Clinical and Experimental Medicine (F.C.), Università Politecnica delle Marche, Ancona, Italy; and Department of Clinical and Experimental Medicine (M.M., L.M., M.S., P.M.), Islet Cell Laboratory, University of Pisa, 56100 Pisa, Italy
| | - Mara Suleiman
- Departments of Medicine (F.C., R.B., J.Y.K.-M., D.A.) and Surgery (Y.O., P.R.S., L.E.R.), Columbia University College of Physicians and Surgeons, New York, New York 10032; Department of Clinical and Experimental Medicine (F.C.), Università Politecnica delle Marche, Ancona, Italy; and Department of Clinical and Experimental Medicine (M.M., L.M., M.S., P.M.), Islet Cell Laboratory, University of Pisa, 56100 Pisa, Italy
| | - Lloyd E Ratner
- Departments of Medicine (F.C., R.B., J.Y.K.-M., D.A.) and Surgery (Y.O., P.R.S., L.E.R.), Columbia University College of Physicians and Surgeons, New York, New York 10032; Department of Clinical and Experimental Medicine (F.C.), Università Politecnica delle Marche, Ancona, Italy; and Department of Clinical and Experimental Medicine (M.M., L.M., M.S., P.M.), Islet Cell Laboratory, University of Pisa, 56100 Pisa, Italy
| | - Piero Marchetti
- Departments of Medicine (F.C., R.B., J.Y.K.-M., D.A.) and Surgery (Y.O., P.R.S., L.E.R.), Columbia University College of Physicians and Surgeons, New York, New York 10032; Department of Clinical and Experimental Medicine (F.C.), Università Politecnica delle Marche, Ancona, Italy; and Department of Clinical and Experimental Medicine (M.M., L.M., M.S., P.M.), Islet Cell Laboratory, University of Pisa, 56100 Pisa, Italy
| | - Domenico Accili
- Departments of Medicine (F.C., R.B., J.Y.K.-M., D.A.) and Surgery (Y.O., P.R.S., L.E.R.), Columbia University College of Physicians and Surgeons, New York, New York 10032; Department of Clinical and Experimental Medicine (F.C.), Università Politecnica delle Marche, Ancona, Italy; and Department of Clinical and Experimental Medicine (M.M., L.M., M.S., P.M.), Islet Cell Laboratory, University of Pisa, 56100 Pisa, Italy
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Shah M, Varghese RT, Miles JM, Piccinini F, Dalla Man C, Cobelli C, Bailey KR, Rizza RA, Vella A. TCF7L2 Genotype and α-Cell Function in Humans Without Diabetes. Diabetes 2016; 65:371-80. [PMID: 26525881 PMCID: PMC4747457 DOI: 10.2337/db15-1233] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 10/26/2015] [Indexed: 12/20/2022]
Abstract
The diabetes-associated allele in TCF7L2 increases the rate of conversion to diabetes; however, the mechanism by which this occurs remains elusive. We hypothesized that the diabetes-associated allele in this locus (rs7903146) impairs insulin secretion and that this defect would be exacerbated by acute free fatty acid (FFA)-induced insulin resistance. We studied 120 individuals of whom one-half were homozygous for the diabetes-associated allele TT at rs7903146 and one-half were homozygous for the protective allele CC. After a screening examination during which glucose tolerance status was determined, subjects were studied on two occasions in random order while undergoing an oral challenge. During one study day, FFA was elevated by infusion of Intralipid plus heparin. On the other study day, subjects received the same amount of glycerol as present in the Intralipid infusion. β-Cell responsivity indices were estimated with the oral C-peptide minimal model. We report that β-cell responsivity was slightly impaired in the TT genotype group. Moreover, the hyperbolic relationship between insulin secretion and β-cell responsivity differed significantly between genotypes. Subjects also exhibited impaired suppression of glucagon after an oral challenge. These data imply that a genetic variant harbored within the TCF7L2 locus impairs glucose tolerance through effects on glucagon as well as on insulin secretion.
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Affiliation(s)
- Meera Shah
- Division of Endocrinology, Diabetes, Metabolism, and Nutrition Research, Mayo Clinic, Rochester, MN
| | - Ron T Varghese
- Division of Endocrinology, Diabetes, Metabolism, and Nutrition Research, Mayo Clinic, Rochester, MN
| | - John M Miles
- Division of Endocrinology, Diabetes, Metabolism, and Nutrition Research, Mayo Clinic, Rochester, MN
| | - Francesca Piccinini
- Department of Information Engineering, Università degli Studi di Padova, Padova, Italy
| | - Chiara Dalla Man
- Department of Information Engineering, Università degli Studi di Padova, Padova, Italy
| | - Claudio Cobelli
- Department of Information Engineering, Università degli Studi di Padova, Padova, Italy
| | - Kent R Bailey
- Division of Biomedical Statistics and Informatics, Mayo Clinic, Rochester, MN
| | - Robert A Rizza
- Division of Endocrinology, Diabetes, Metabolism, and Nutrition Research, Mayo Clinic, Rochester, MN
| | - Adrian Vella
- Division of Endocrinology, Diabetes, Metabolism, and Nutrition Research, Mayo Clinic, Rochester, MN
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Sato S, Saisho Y, Inaishi J, Kou K, Murakami R, Yamada T, Itoh H. Effects of Glucocorticoid Treatment on β- and α-Cell Mass in Japanese Adults With and Without Diabetes. Diabetes 2015; 64:2915-27. [PMID: 25883114 DOI: 10.2337/db15-0151] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 04/11/2015] [Indexed: 11/13/2022]
Abstract
The aim of this study was 1) to clarify β-cell regenerative capacity in the face of glucocorticoid (GC)-induced insulin resistance and 2) to clarify the change in β- and α-cell mass in GC-induced diabetes in humans. We obtained the pancreases from 100 Japanese autopsy case subjects. The case subjects were classified according to whether or not they had received GC therapy before death and the presence or absence of diabetes. Fractional β-cell area (%BCA) and α-cell area (%ACA) were quantified, and the relationship with GC therapy was evaluated. As a result, in case subjects without diabetes, there was no significant difference in %BCA between case subjects with and without GC therapy (1.66 ± 1.05% vs. 1.21 ± 0.59%, P = 0.13). %ACA was also not significantly different between the two groups. In case subjects with type 2 diabetes, %BCA and %ACA were both significantly reduced compared with control subjects without diabetes; however, neither %BCA nor %ACA was significantly decreased in case subjects with GC-induced diabetes. There was a significant negative correlation between %BCA and HbA1c measured before death; however, this relationship was attenuated in case subjects with GC therapy. In conclusion, the current study suggests that β- and α-cell mass remain largely unchanged in the face of GC-induced insulin resistance in Japanese individuals, implying limited capacity of β-cell regeneration in adult humans. The absence of apparent β-cell deficit in case subjects with GC-induced diabetes suggests that GC-induced diabetes is mainly caused by insulin resistance and/or β-cell dysfunction, but not necessarily a deficit of β-cell mass.
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Affiliation(s)
- Seiji Sato
- Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan
| | - Yoshifumi Saisho
- Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan
| | - Jun Inaishi
- Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan
| | - Kinsei Kou
- Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan
| | - Rie Murakami
- Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan
| | - Taketo Yamada
- Department of Pathology, Keio University School of Medicine, Tokyo, Japan
| | - Hiroshi Itoh
- Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan
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21
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Abstract
Glucagon is secreted from islet α cells and controls blood levels of glucose in the fasting state. Impaired glucagon secretion predisposes some patients with type 1 diabetes mellitus (T1DM) to hypoglycaemia; whereas hyperglycaemia in patients with T1DM or type 2 diabetes mellitus (T2DM) is often associated with hyperglucagonaemia. Hence, therapeutic strategies to safely achieve euglycaemia in patients with diabetes mellitus now encompass bihormonal approaches to simultaneously deliver insulin and glucagon (in patients with T1DM) or reduce excess glucagon action (in patients with T1DM or T2DM). Glucagon also reduces food intake and increases energy expenditure through central and peripheral mechanisms, which suggests that activation of signalling through the glucagon receptor might be useful for controlling body weight. Here, we review new data that is relevant to understanding α-cell biology and glucagon action in the brain, liver, adipose tissue and heart, with attention to normal physiology, as well as conditions associated with dysregulated glucagon action. The feasibility and safety of current and emerging glucagon-based therapies that encompass both gain-of-function and loss-of-function approaches for the treatment of T1DM, T2DM and obesity is discussed in addition to developments, challenges and critical gaps in our knowledge that require additional investigation.
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Affiliation(s)
- Jonathan E Campbell
- Department of Medicine, Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, University of Toronto, 600 University Avenue, TCP5-1004, Toronto, ON M5G 1X5, Canada
| | - Daniel J Drucker
- Department of Medicine, Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, University of Toronto, 600 University Avenue, TCP5-1004, Toronto, ON M5G 1X5, Canada
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22
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Wu YX, Sun RQ, Yin GS, Xu DC, Wang P, Lin K, Lin CJ, Lin SD. Different effect of handle region peptide on β-cell function in different sexes of rats neonatally treated with sodium L-glutamate. Med Sci Monit Basic Res 2015; 21:33-40. [PMID: 25783768 PMCID: PMC4428315 DOI: 10.12659/msmbr.893183] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2014] [Accepted: 02/02/2015] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND The (pro)renin receptor ((P)RR) was reported to be expressed in various tissues including the pancreas, and handle region peptide (HRP) is believed to block the function of (P)RR. This study aimed to investigate the effect of HRP on the glucose tolerance status and β-cell function of female rats, neonatally treated with sodium L-glutamate (MSG) and to compare with the previously reported HRP effect on male rats. MATERIAL AND METHODS Female MSG rats aged 8 weeks were divided into MSG control group and HRP treated group and the normal SD rats served as control. The MSG rats were treated with HRP by osmotic minipumps with dose of 1 mg/kg per day for total 28 days. Glucose tolerance status was evaluated at the end of the study. Islets α-cell and β-cell were marked with insulin antibody and glucagon antibody respectively. The proliferation of islet cells and expression of subunit of NADPH oxidase P22phox were marked by PCNA and P22phox antibody. Picrosirius red staining was performed for evaluating fibrosis of islets. RESULTS HRP improved the glucose status tolerance with decreasing α-cell mass, islets PCNA-positive cells, expression of P22phox and picrosirius red stained areas, and increasing β-cell mass in female MSG rats. The indexes with obviously interacted effect of sexes and HRP for the MSG rats were the AUC of blood glucose concentration (P<0.01), α-cell mass (P<0.05), proliferation of islet cells (P<0.01) and area of picrosirius red staining (P<0.01). CONCLUSIONS HRP improved the glucose tolerance status in the females although it was previously reported to worsen the glucose tolerance in male MSG rats. Different levels of sex hormones may partly account for the disparate effects observed for HRP in different sexes.
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Affiliation(s)
- Yi-xi Wu
- Department of Endocrinology and Metabolism, The First Affiliated Hospital of Shantou University Medical College, Shantou, Guangdong, China
| | - Ru-qiong Sun
- Department of Endocrinology and Metabolism, The First Affiliated Hospital of Shantou University Medical College, Shantou, Guangdong, China
- Department of Endocrinology and Metabolism, Tongxiang First People Hospital, Tongxiang, Zhejiang, China
| | - Guo-shu Yin
- Department of Endocrinology and Metabolism, The First Affiliated Hospital of Shantou University Medical College, Shantou, Guangdong, China
- Corresponding Authors: Guo-shu Yin, e-mail: and Shao-da Lin, e-mail:
| | - Dong-chuan Xu
- Department of Endocrinology and Metabolism, The First Affiliated Hospital of Shantou University Medical College, Shantou, Guangdong, China
| | - Ping Wang
- Department of Endocrinology and Metabolism, The First Affiliated Hospital of Shantou University Medical College, Shantou, Guangdong, China
| | - Kun Lin
- Department of Endocrinology and Metabolism, The First Affiliated Hospital of Shantou University Medical College, Shantou, Guangdong, China
| | - Chu-jia Lin
- Department of Endocrinology and Metabolism, The First Affiliated Hospital of Shantou University Medical College, Shantou, Guangdong, China
| | - Shao-da Lin
- Department of Endocrinology and Metabolism, The First Affiliated Hospital of Shantou University Medical College, Shantou, Guangdong, China
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Robertson RP, Bogachus LD, Oseid E, Parazzoli S, Patti ME, Rickels MR, Schuetz C, Dunn T, Pruett T, Balamurugan AN, Sutherland DER, Beilman G, Bellin MD. Assessment of β-cell mass and α- and β-cell survival and function by arginine stimulation in human autologous islet recipients. Diabetes 2015; 64:565-72. [PMID: 25187365 PMCID: PMC4303963 DOI: 10.2337/db14-0690] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We used intravenous arginine with measurements of insulin, C-peptide, and glucagon to examine β-cell and α-cell survival and function in a group of 10 chronic pancreatitis recipients 1-8 years after total pancreatectomy and autoislet transplantation. Insulin and C-peptide responses correlated robustly with the number of islets transplanted (correlation coefficients range 0.81-0.91; P < 0.01-0.001). Since a wide range of islets were transplanted, we normalized the insulin and C-peptide responses to the number of islets transplanted in each recipient for comparison with responses in normal subjects. No significant differences were observed in terms of magnitude and timing of hormone release in the two groups. Three recipients had a portion of the autoislets placed within their peritoneal cavities, which appeared to be functioning normally up to 7 years posttransplant. Glucagon responses to arginine were normally timed and normally suppressed by intravenous glucose infusion. These findings indicate that arginine stimulation testing may be a means of assessing the numbers of native islets available in autologous islet transplant candidates and is a means of following posttransplant α- and β-cell function and survival.
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Affiliation(s)
- R Paul Robertson
- Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, University of Washington, Seattle, WA Departments of Pediatrics and Surgery, University of Minnesota, Minneapolis, MN Pacific Northwest Diabetes Research Institute, Seattle, WA
| | - Lindsey D Bogachus
- Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, University of Washington, Seattle, WA Pacific Northwest Diabetes Research Institute, Seattle, WA
| | | | | | | | - Michael R Rickels
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA
| | | | - Ty Dunn
- Departments of Pediatrics and Surgery, University of Minnesota, Minneapolis, MN
| | - Timothy Pruett
- Departments of Pediatrics and Surgery, University of Minnesota, Minneapolis, MN
| | - A N Balamurugan
- Departments of Pediatrics and Surgery, University of Minnesota, Minneapolis, MN
| | | | - Gregory Beilman
- Departments of Pediatrics and Surgery, University of Minnesota, Minneapolis, MN
| | - Melena D Bellin
- Departments of Pediatrics and Surgery, University of Minnesota, Minneapolis, MN
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Abstract
Agents that stimulate human pancreatic beta cell proliferation are needed to improve diabetes mellitus treatment. Recently, a small molecule, WS6, was observed to stimulate human beta cell proliferation. However, little is known about its other effects on human islets. To better understand the role of WS6 as a possible beta cell regenerative therapy, we carried out in-depth phenotypic analysis of WS6-treated human islets, exploring its effects on non-beta cell proliferation, beta cell differentiation, and islet cell viability. WS6 not only stimulated beta cell proliferation in cultured human islets (in agreement with previous reports), but also human alpha cell proliferation, indicating that WS6 is not a beta cell-specific mitogen. WS6 did not change the proportion of insulin-positive beta cells or the expression of beta cell-specific transcription factors, suggesting that WS6 does not alter beta cell differentiation, and WS6 had no effect on human islet cell apoptosis or viability. In conclusion, WS6 stimulates proliferation of both human beta and alpha cells while maintaining cellular viability and the beta cell differentiated phenotype. These findings expand the literature on WS6 and support the suggestion that WS6 may help increase human islet mass needed for successful treatment of diabetes.
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Affiliation(s)
- Brian P. Boerner
- Holland Regenerative Medicine Program, University of Nebraska Medical Center, Omaha, NE 68198, USA
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Nicholas M. George
- Holland Regenerative Medicine Program, University of Nebraska Medical Center, Omaha, NE 68198, USA
- Department of Surgery, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Shakeel U.R. Mir
- Holland Regenerative Medicine Program, University of Nebraska Medical Center, Omaha, NE 68198, USA
- Department of Surgery, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Nora E. Sarvetnick
- Holland Regenerative Medicine Program, University of Nebraska Medical Center, Omaha, NE 68198, USA
- Department of Surgery, University of Nebraska Medical Center, Omaha, NE 68198, USA
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25
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Li F, Su Y, Cheng Y, Jiang X, Peng Y, Li Y, Lu J, Gu Y, Zhang C, Cao Y, Wang W, Ning G. Conditional deletion of Men1 in the pancreatic β-cell leads to glucagon-expressing tumor development. Endocrinology 2015; 156:48-57. [PMID: 25343275 DOI: 10.1210/en.2014-1433] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The tumor suppressor menin is recognized as a key regulator of β-cell proliferation. To induce tumorigenesis within the pancreatic β-cells, floxed alleles of Men1 were selectively ablated using Cre-recombinase driven by the insulin promoter. Despite the β-cell specificity of the RipCre, glucagon-expressing tumors as well as insulinomas developed in old mutant mice. These glucagon-expressing tumor cells were menin deficient and expressed the mature α-cell-specific transcription factors Brain-specific homeobox POU domain protein 4 (Brn4) and v-maf musculoaponeurotic fibrosarcoma oncogene family, protein B (MafB). Moreover, the inactivation of β-cell-specific transcription factors was observed in mutant β-cells. Our work shows that Men1 ablation in the pancreatic β-cells leads to the inactivation of specific transcription factors, resulting in glucagon-expressing tumor development, which sheds light on the mechanisms of islet tumorigenesis.
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Affiliation(s)
- Feng Li
- Department of Endocrinology and Metabolism (F.L., Y.S., Y.Ch., X.J., Y.P., Y.L., J.L., Y.G., Y.Ca., W.W., G.N.), Shanghai Clinical Center for Endocrine and Metabolic Diseases and Shanghai Institute of Endocrinology and Metabolism, Rui-Jin Hospital, Shanghai Jiao-Tong University School of Medicine, and Laboratory of Endocrinology and Metabolism (G.N.), Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, and Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China; and Laboratoire Génétique Moléculaire, Signalisation et Cancer (C.Z.), Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5201, Faculté de Médecine, Université Claude Bernard Lyon, Centre Leon-Berard, Lyon69366, France
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26
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Wang L, Luk CT, Cai EP, Schroer SA, Allister EM, Shi SY, Wheeler MB, Gaisano HY, Woo M. PTEN deletion in pancreatic α-cells protects against high-fat diet-induced hyperglucagonemia and insulin resistance. Diabetes 2015; 64:147-57. [PMID: 25092678 DOI: 10.2337/db13-1715] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
An aberrant increase in circulating catabolic hormone glucagon contributes to type 2 diabetes pathogenesis. However, mechanisms regulating glucagon secretion and α-cell mass are not well understood. In this study, we aimed to demonstrate that phosphatidylinositol 3-kinase (PI3K) signaling is an important regulator of α-cell function. Mice with deletion of PTEN, a negative regulator of this pathway, in α-cells show reduced circulating glucagon levels and attenuated l-arginine-stimulated glucagon secretion both in vivo and in vitro. This hypoglucagonemic state is maintained after high-fat-diet feeding, leading to reduced expression of hepatic glycogenolytic and gluconeogenic genes. These beneficial effects protected high-fat diet-fed mice against hyperglycemia and insulin resistance. The data demonstrate an inhibitory role of PI3K signaling on α-cell function and provide experimental evidence for enhancing α-cell PI3K signaling for diabetes treatment.
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Affiliation(s)
- Linyuan Wang
- Toronto General Research Institute, University Health Network, Toronto, ON, Canada Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Cynthia T Luk
- Toronto General Research Institute, University Health Network, Toronto, ON, Canada Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - Erica P Cai
- Toronto General Research Institute, University Health Network, Toronto, ON, Canada Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - Stephanie A Schroer
- Toronto General Research Institute, University Health Network, Toronto, ON, Canada
| | - Emma M Allister
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Sally Y Shi
- Toronto General Research Institute, University Health Network, Toronto, ON, Canada Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - Michael B Wheeler
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Herbert Y Gaisano
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Minna Woo
- Toronto General Research Institute, University Health Network, Toronto, ON, Canada Institute of Medical Science, University of Toronto, Toronto, ON, Canada Division of Endocrinology & Metabolism, Department of Medicine, University Health Network, Toronto, ON, Canada
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27
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Heddad Masson M, Poisson C, Guérardel A, Mamin A, Philippe J, Gosmain Y. Foxa1 and Foxa2 regulate α-cell differentiation, glucagon biosynthesis, and secretion. Endocrinology 2014; 155:3781-92. [PMID: 25057789 DOI: 10.1210/en.2013-1843] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The Forkhead box A transcription factors are major regulators of glucose homeostasis. They show both distinct and redundant roles during pancreas development and in adult mouse β-cells. In vivo ablation studies have revealed critical implications of Foxa1 on glucagon biosynthesis and requirement of Foxa2 in α-cell terminal differentiation. In order to examine the respective role of these factors in mature α-cells, we used small interfering RNA (siRNA) directed against Foxa1 and Foxa2 in rat primary pancreatic α-cells and rodent α-cell lines leading to marked decreases in Foxa1 and Foxa2 mRNA levels and proteins. Both Foxa1 and Foxa2 control glucagon gene expression specifically through the G2 element. Although we found that Foxa2 controls the expression of the glucagon, MafB, Pou3f4, Pcsk2, Nkx2.2, Kir6.2, and Sur1 genes, Foxa1 only regulates glucagon gene expression. Interestingly, the Isl1 and Gipr genes were not controlled by either Foxa1 or Foxa2 alone but by their combination. Foxa1 and Foxa2 directly activate and bind the promoter region the Nkx2.2, Kir6.2 and Sur1, Gipr, Isl1, and Pou3f4 genes. We also demonstrated that glucagon secretion is affected by the combined effects of Foxa1 and Foxa2 but not by either one alone. Our results indicate that Foxa1 and Foxa2 control glucagon biosynthesis and secretion as well as α-cell differentiation with both common and unique target genes.
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Affiliation(s)
- Mounia Heddad Masson
- Department of Endocrinology, Diabetes, Hypertension and Nutrition, University Hospital of Geneva, Medical School, 1211 Geneva 14, Switzerland
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28
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Rafacho A, Gonçalves-Neto LM, Santos-Silva JC, Alonso-Magdalena P, Merino B, Taboga SR, Carneiro EM, Boschero AC, Nadal A, Quesada I. Pancreatic alpha-cell dysfunction contributes to the disruption of glucose homeostasis and compensatory insulin hypersecretion in glucocorticoid-treated rats. PLoS One 2014; 9:e93531. [PMID: 24705399 PMCID: PMC3976288 DOI: 10.1371/journal.pone.0093531] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Accepted: 03/04/2014] [Indexed: 12/11/2022] Open
Abstract
Glucocorticoid (GC)-based therapies can cause insulin resistance (IR), glucose intolerance, hyperglycemia and, occasionally, overt diabetes. Understanding the mechanisms behind these metabolic disorders could improve the management of glucose homeostasis in patients undergoing GC treatment. For this purpose, adult rats were treated with a daily injection of dexamethasone (1 mg/kg b.w., i.p.) (DEX) or saline as a control for 5 consecutive days. The DEX rats developed IR, augmented glycemia, hyperinsulinemia and hyperglucagonemia. Treatment of the DEX rats with a glucagon receptor antagonist normalized their blood glucose level. The characteristic inhibitory effect of glucose on glucagon secretion was impaired in the islets of the DEX rats, while no direct effects were found on α-cells in islets that were incubated with DEX in vitro. A higher proportion of docked secretory granules was found in the DEX α-cells as well as a trend towards increased α-cell mass. Additionally, insulin secretion in the presence of glucagon was augmented in the islets of the DEX rats, which was most likely due to their higher glucagon receptor content. We also found that the enzyme 11βHSD-1, which participates in GC metabolism, contributed to the insulin hypersecretion in the DEX rats under basal glucose conditions. Altogether, we showed that GC treatment induces hyperglucagonemia, which contributes to an imbalance in glucose homeostasis and compensatory β-cell hypersecretion. This hyperglucagonemia may result from altered α-cell function and, likely, α-cell mass. Additionally, blockage of the glucagon receptor seems to be effective in preventing the elevation in blood glucose levels induced by GC administration.
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Affiliation(s)
- Alex Rafacho
- Department of Physiological Sciences, Center of Biological Sciences, Federal University of Santa Catarina (UFSC), Florianópolis, Brazil
- * E-mail: (AR); (IQ)
| | - Luiz M. Gonçalves-Neto
- Department of Physiological Sciences, Center of Biological Sciences, Federal University of Santa Catarina (UFSC), Florianópolis, Brazil
| | - Junia C. Santos-Silva
- Department of Structural and Functional Biology, Institute of Biology, and Obesity and Comorbidities Research Center (OCRC), State University of Campinas (UNICAMP), Campinas, Brazil
| | - Paloma Alonso-Magdalena
- Institute of Bioengineering and the Biomedical Research Center in Diabetes and Associated Metabolic Disorders (CIBERDEM), Miguel Hernández University, Elche, Spain
| | - Beatriz Merino
- Institute of Bioengineering and the Biomedical Research Center in Diabetes and Associated Metabolic Disorders (CIBERDEM), Miguel Hernández University, Elche, Spain
| | - Sebastião R. Taboga
- Department of Biology, Institute of Biosciences, Humanities and Exact Sciences, São Paulo State University (UNESP), São José do Rio Preto, Brazil
| | - Everardo M. Carneiro
- Department of Structural and Functional Biology, Institute of Biology, and Obesity and Comorbidities Research Center (OCRC), State University of Campinas (UNICAMP), Campinas, Brazil
| | - Antonio C. Boschero
- Department of Structural and Functional Biology, Institute of Biology, and Obesity and Comorbidities Research Center (OCRC), State University of Campinas (UNICAMP), Campinas, Brazil
| | - Angel Nadal
- Institute of Bioengineering and the Biomedical Research Center in Diabetes and Associated Metabolic Disorders (CIBERDEM), Miguel Hernández University, Elche, Spain
| | - Ivan Quesada
- Institute of Bioengineering and the Biomedical Research Center in Diabetes and Associated Metabolic Disorders (CIBERDEM), Miguel Hernández University, Elche, Spain
- * E-mail: (AR); (IQ)
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29
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Abstract
Glucose metabolism is normally regulated by a feedback loop including islet β cells and insulin-sensitive tissues, in which tissue sensitivity to insulin affects magnitude of β-cell response. If insulin resistance is present, β cells maintain normal glucose tolerance by increasing insulin output. Only when β cells cannot release sufficient insulin in the presence of insulin resistance do glucose concentrations rise. Although β-cell dysfunction has a clear genetic component, environmental changes play an essential part. Modern research approaches have helped to establish the important role that hexoses, aminoacids, and fatty acids have in insulin resistance and β-cell dysfunction, and the potential role of changes in the microbiome. Several new approaches for treatment have been developed, but more effective therapies to slow progressive loss of β-cell function are needed. Recent findings from clinical trials provide important information about methods to prevent and treat type 2 diabetes and some of the adverse effects of these interventions. However, additional long-term studies of drugs and bariatric surgery are needed to identify new ways to prevent and treat type 2 diabetes and thereby reduce the harmful effects of this disease.
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Affiliation(s)
- Steven E Kahn
- Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, VA Puget Sound Health Care System, University of Washington, Seattle, WA, USA.
| | - Mark E Cooper
- Diabetes Division, Baker IDI Heart and Diabetes Institute, Melbourne, VIC, Australia
| | - Stefano Del Prato
- Department of Clinical and Experimental Medicine, University of Pisa School of Medicine, Pisa, Italy
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30
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Li W, Nakanishi M, Zumsteg A, Shear M, Wright C, Melton DA, Zhou Q. In vivo reprogramming of pancreatic acinar cells to three islet endocrine subtypes. eLife 2014; 3:e01846. [PMID: 24714494 PMCID: PMC3977343 DOI: 10.7554/elife.01846] [Citation(s) in RCA: 103] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Accepted: 02/20/2014] [Indexed: 12/15/2022] Open
Abstract
Direct lineage conversion of adult cells is a promising approach for regenerative medicine. A major challenge of lineage conversion is to generate specific cell subtypes. The pancreatic islets contain three major hormone-secreting endocrine subtypes: insulin(+) β-cells, glucagon(+) α-cells, and somatostatin(+) δ-cells. We previously reported that a combination of three transcription factors, Ngn3, Mafa, and Pdx1, directly reprograms pancreatic acinar cells to β-cells. We now show that acinar cells can be converted to δ-like and α-like cells by Ngn3 and Ngn3+Mafa respectively. Thus, three major islet endocrine subtypes can be derived by acinar reprogramming. Ngn3 promotes establishment of a generic endocrine state in acinar cells, and also promotes δ-specification in the absence of other factors. δ-specification is in turn suppressed by Mafa and Pdx1 during α- and β-cell induction. These studies identify a set of defined factors whose combinatorial actions reprogram acinar cells to distinct islet endocrine subtypes in vivo. DOI: http://dx.doi.org/10.7554/eLife.01846.001.
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Affiliation(s)
- Weida Li
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, United States
| | - Mio Nakanishi
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, United States
- Stem Cell and Cancer Research Institute, McMaster University, Ontario, Canada
| | - Adrian Zumsteg
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, United States
| | - Matthew Shear
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, United States
| | - Christopher Wright
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, United States
| | - Douglas A Melton
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, United States
| | - Qiao Zhou
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, United States
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31
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Brown ML, Ungerleider N, Bonomi L, Andrzejewski D, Burnside A, Schneyer A. Effects of activin A on survival, function and gene expression of pancreatic islets from non-diabetic and diabetic human donors. Islets 2014; 6:e1017226. [PMID: 25833251 PMCID: PMC4398300 DOI: 10.1080/19382014.2015.1017226] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Emerging evidence suggests that activin with its associated receptors, second messengers, and antagonists would be excellent targets for therapeutic drug development in the treatment of diabetes. We undertook the current study to investigate the ability to extrapolate findings from rodent studies to human islets in which data thus far has been scarce. We tested the hypothesis that human islets synthesize activin and that activin participates in the regulation of islet β-cells. Human islets from 33 separate isolations were categorized based on functional status, culture status and diabetic status. Statistical comparisons were made by ANOVA with Tukey post-hoc adjustment for multiple comparisons. Experiments investigating activin utilized qPCR, FACS cell sorting, immunofluorescent antibody staining, functionality assays, viability assays and protein secretion assays. We have defined the transcript expression patterns of activin and the TGFβ superfamily in human islets. We found INHBA (the gene encoding activin A) to be the most highly expressed of the superfamily in normal, cultured islets. We elucidated a link between the islet microenvironment and activin A. We found differential ligand expression based on diabetic, culture and functional status. Further, this is also the first report that links direct effects of activin A with the ability to restore glucose-stimulated insulin secretion in human islets from type 2 diabetic donors thereby establishing the relevance of targeting activin for therapeutic drug development.
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Affiliation(s)
- Melissa L Brown
- University of Massachusetts
Amherst; Amherst, MA USA
- Pioneer Valley Life Sciences
Institute; Springfield, MA USA
- Department of Nutrition; University of
Massachusetts; Amherst, MA USA
- Correspondence to: Melissa L Brown;
| | - Nathan Ungerleider
- University of Massachusetts
Amherst; Amherst, MA USA
- Pioneer Valley Life Sciences
Institute; Springfield, MA USA
| | - Lara Bonomi
- University of Massachusetts
Amherst; Amherst, MA USA
- Pioneer Valley Life Sciences
Institute; Springfield, MA USA
| | - Danielle Andrzejewski
- University of Massachusetts
Amherst; Amherst, MA USA
- Pioneer Valley Life Sciences
Institute; Springfield, MA USA
- Department of Veterinary and Animal Sciences;
University of Massachusetts; Amherst, MA USA
| | - Amy Burnside
- University of Massachusetts
Amherst; Amherst, MA USA
- Pioneer Valley Life Sciences
Institute; Springfield, MA USA
- Department of Veterinary and Animal Sciences;
University of Massachusetts; Amherst, MA USA
| | - Alan Schneyer
- University of Massachusetts
Amherst; Amherst, MA USA
- Pioneer Valley Life Sciences
Institute; Springfield, MA USA
- Department of Veterinary and Animal Sciences;
University of Massachusetts; Amherst, MA USA
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32
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Wilcox CL, Terry NA, May CL. Arx polyalanine expansion in mice leads to reduced pancreatic α-cell specification and increased α-cell death. PLoS One 2013; 8:e78741. [PMID: 24236044 PMCID: PMC3827280 DOI: 10.1371/journal.pone.0078741] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2013] [Accepted: 09/23/2013] [Indexed: 11/18/2022] Open
Abstract
ARX/Arx is a homeodomain-containing transcription factor necessary for the specification and early maintenance of pancreatic endocrine α-cells. Many transcription factors important to pancreas development, including ARX/Arx, are also crucial for proper brain development. Although null mutations of ARX in human patients result in the severe neurologic syndrome XLAG (X-linked lissencephaly associated with abnormal genitalia), the most common mutation is the expansion of the first polyalanine tract of ARX, which results primarily in the clinical syndrome ISSX (infantile spasms). Mouse models of XLAG, ISSX and other human ARX mutations demonstrate a direct genotype-phenotype correlation in ARX-related neurologic disorders. Furthermore, mouse models utilizing a polyalanine tract expansion mutation have illustrated critical developmental differences between null mutations and expansion mutations in the brain, revealing context-specific defects. Although Arx is known to be required for the specification and early maintenance of pancreatic glucagon-producing α-cells, the consequences of the Arx polyalanine expansion on pancreas development remain unknown. Here we report that mice with an expansion mutation in the first polyalanine tract of Arx exhibit impaired α-cell specification and maintenance, with gradual α-cell loss due to apoptosis. This is in contrast to the re-specification of α-cells into β- and δ-cells that occurs in mice null for Arx. Overall, our analysis of an Arx polyalanine expansion mutation on pancreatic development suggests that impaired α-cell function might also occur in ISSX patients.
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Affiliation(s)
- Crystal L. Wilcox
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
| | - Natalie A. Terry
- Department of Pediatrics, Division of Gastroenterology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
| | - Catherine Lee May
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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33
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Shiota C, Prasadan K, Guo P, El-Gohary Y, Wiersch J, Xiao X, Esni F, Gittes GK. α-Cells are dispensable in postnatal morphogenesis and maturation of mouse pancreatic islets. Am J Physiol Endocrinol Metab 2013; 305:E1030-40. [PMID: 23982158 DOI: 10.1152/ajpendo.00022.2013] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Glucagon-producing α-cells are the second-most abundant cell type in the islet. Whereas α-cells make up less than 20% of the cells in a mature mouse islet, they occupy a much larger proportion of the pancreatic endocrine cell population during the early postnatal period, the time when morphological and functional maturation occurs to form adult islets. To determine whether α-cells have a role in postnatal islet development, a diphtheria toxin-mediated α-cell ablation mouse model was established. Rapid and persistent depletion of α-cells was achieved by daily injection of the toxin for 2 wk starting at postnatal day 1 (P1). Total pancreatic glucagon content in the α-cell-ablated mice was undetectable at P14 and still less than 0.3% of that of the control mice at 4 mo of age. Histological analyses revealed that formation of spherical islets occurred normally, and the islet size distribution was not changed despite the near-total lack of α-cells. Furthermore, there were no differences in expression of β-cell maturation marker proteins, including urocortin 3 and glucose transporter 2, in the α-cell-ablated islets at P14. Mice lacking α-cells grew normally and appeared healthy. Both glucose and insulin tolerance tests demonstrated that the α-cell-ablated mice had normal glucose homeostasis. These results indicate that α-cells do not play a critical role in postnatal islet morphogenesis or functional maturation of β-cells.
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Affiliation(s)
- Chiyo Shiota
- Division of Pediatric General and Thoracic Surgery, Children's Hospital of Pittsburgh of UPMC, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
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34
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Longuet C, Robledo AM, Dean ED, Dai C, Ali S, McGuinness I, de Chavez V, Vuguin PM, Charron MJ, Powers AC, Drucker DJ. Liver-specific disruption of the murine glucagon receptor produces α-cell hyperplasia: evidence for a circulating α-cell growth factor. Diabetes 2013; 62:1196-205. [PMID: 23160527 PMCID: PMC3609565 DOI: 10.2337/db11-1605] [Citation(s) in RCA: 138] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Glucagon is a critical regulator of glucose homeostasis; however, mechanisms regulating glucagon action and α-cell function and number are incompletely understood. To elucidate the role of the hepatic glucagon receptor (Gcgr) in glucagon action, we generated mice with hepatocyte-specific deletion of the glucagon receptor. Gcgr(Hep)(-/-) mice exhibited reductions in fasting blood glucose and improvements in insulin sensitivity and glucose tolerance compared with wild-type controls, similar in magnitude to changes observed in Gcgr(-/-) mice. Despite preservation of islet Gcgr signaling, Gcgr(Hep)(-/-) mice developed hyperglucagonemia and α-cell hyperplasia. To investigate mechanisms by which signaling through the Gcgr regulates α-cell mass, wild-type islets were transplanted into Gcgr(-/-) or Gcgr(Hep)(-/-) mice. Wild-type islets beneath the renal capsule of Gcgr(-/-) or Gcgr(Hep)(-/-) mice exhibited an increased rate of α-cell proliferation and expansion of α-cell area, consistent with changes exhibited by endogenous α-cells in Gcgr(-/-) and Gcgr(Hep)(-/-) pancreata. These results suggest that a circulating factor generated after disruption of hepatic Gcgr signaling can increase α-cell proliferation independent of direct pancreatic input. Identification of novel factors regulating α-cell proliferation and mass may facilitate the generation and expansion of α-cells for transdifferentiation into β-cells and the treatment of diabetes.
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Affiliation(s)
- Christine Longuet
- Department of Medicine, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, The University of Toronto, Toronto, Ontario, Canada
| | - Ana M. Robledo
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - E. Danielle Dean
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Chunhua Dai
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Safina Ali
- Department of Medicine, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, The University of Toronto, Toronto, Ontario, Canada
| | - Ian McGuinness
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Vincent de Chavez
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Patricia M. Vuguin
- Division of Pediatric Endocrinology, Steven & Alexandra Cohen Children’s Medical Center of New York, Long Island, New York
| | - Maureen J. Charron
- Albert Einstein College of Medicine, Departments of Biochemistry, Medicine, and Obstetrics & Gynecology, Bronx, New York
| | - Alvin C. Powers
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, Tennessee
- VA Tennessee Valley Healthcare System, Nashville, Tennessee
- Corresponding author: Alvin C. Powers, , or Daniel J. Drucker,
| | - Daniel J. Drucker
- Department of Medicine, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, The University of Toronto, Toronto, Ontario, Canada
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Abstract
The alpha cells that coinhabit the islets with the insulin-producing beta cells have recently captured the attention of diabetes researchers because of new breakthrough findings highlighting the importance of these cells in the maintenance of beta cell health and functions. In normal physiological conditions alpha cells produce glucagon but in conditions of beta cell injury they also produce glucagon-like peptide-1 (GLP-1), a growth and survival factor for beta cells. In this review we consider these new findings on the functions of alpha cells. Alpha cells remain somewhat enigmatic inasmuch as they now appear to be important in the maintenance of the health of beta cells, but their production of glucagon promotes diabetes. This circumstance prompts an examination of approaches to coax alpha cells to produce GLP-1 instead of glucagon.
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Affiliation(s)
- Joel F Habener
- Laboratory of Molecular Endocrinology, Massachusetts General Hospital, Boston, MA 02114, USA.
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36
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Huang YC, Rupnik MS, Karimian N, Herrera PL, Gilon P, Feng ZP, Gaisano HY. In situ electrophysiological examination of pancreatic α cells in the streptozotocin-induced diabetes model, revealing the cellular basis of glucagon hypersecretion. Diabetes 2013; 62:519-30. [PMID: 23043159 PMCID: PMC3554363 DOI: 10.2337/db11-0786] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Early-stage type 1 diabetes (T1D) exhibits hyperglucagonemia by undefined cellular mechanisms. Here we characterized α-cell voltage-gated ion channels in a streptozotocin (STZ)-induced diabetes model that lead to increased glucagon secretion mimicking T1D. GYY mice expressing enhanced yellow fluorescence protein in α cells were used to identify α cells within pancreas slices. Mice treated with low-dose STZ exhibited hyperglucagonemia, hyperglycemia, and glucose intolerance, with 71% reduction of β-cell mass. Although α-cell mass of STZ-treated mice remained unchanged, total pancreatic glucagon content was elevated, coinciding with increase in size of glucagon granules. Pancreas tissue slices enabled in situ examination of α-cell electrophysiology. α cells of STZ-treated mice exhibited the following: 1) increased exocytosis (serial depolarization-induced capacitance), 2) enhanced voltage-gated Na(+) current density, 3) reduced voltage-gated K(+) current density, and 4) increased action potential (AP) amplitude and firing frequency. Hyperglucagonemia in STZ-induced diabetes is thus likely due to increased glucagon content arising from enlarged glucagon granules and increased AP firing frequency and amplitude coinciding with enhanced Na(+) and reduced K(+) currents. These alterations may prime α cells in STZ-treated mice for more glucagon release per cell in response to low glucose stimulation. Thus, our study provides the first insight that STZ treatment sensitizes release mechanisms of α cells.
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Affiliation(s)
- Ya-Chi Huang
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
| | - Marjan S. Rupnik
- Faculty of Medicine, Institute of Physiology/CIPKEBIP, University of Maribor, Maribor, Slovenia
| | - Negar Karimian
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
| | - Pedro L. Herrera
- Cell Physiology & Metabolism, University of Geneva, Geneva, Switzerland
| | - Patrick Gilon
- Pole d’Endocrinologie, Diabète et Nutrition, Université Catholique de Louvain, Brussels, Belgium
| | - Zhong-Ping Feng
- Physiology and Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Herbert Y. Gaisano
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
- Physiology and Medicine, University of Toronto, Toronto, Ontario, Canada
- Corresponding author: Herbert Y. Gaisano,
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37
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Pedersen J, Ugleholdt RK, Jørgensen SM, Windeløv JA, Grunddal KV, Schwartz TW, Füchtbauer EM, Poulsen SS, Holst PJ, Holst JJ. Glucose metabolism is altered after loss of L cells and α-cells but not influenced by loss of K cells. Am J Physiol Endocrinol Metab 2013; 304:E60-73. [PMID: 23115082 DOI: 10.1152/ajpendo.00547.2011] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The enteroendocrine K and L cells are responsible for secretion of glucose-dependent insulinotropic polypeptide (GIP) and glucagon like-peptide 1 (GLP-1), whereas pancreatic α-cells are responsible for secretion of glucagon. In rodents and humans, dysregulation of the secretion of GIP, GLP-1, and glucagon is associated with impaired regulation of metabolism. This study evaluates the consequences of acute removal of Gip- or Gcg-expressing cells on glucose metabolism. Generation of the two diphtheria toxin receptor cellular knockout mice, TgN(GIP.DTR) and TgN(GCG.DTR), allowed us to study effects of acute ablation of K and L cells and α-cells. Diphtheria toxin administration reduced the expression of Gip and content of GIP in the proximal jejunum in TgN(GIP.DTR) and expression of Gcg and content of proglucagon-derived peptides in both proximal jejunum and terminal ileum as well as content of glucagon in pancreas in TgN(GCG.DTR) compared with wild-type mice. GIP response to oral glucose was attenuated following K cell loss, but oral and intraperitoneal glucose tolerances were unaffected. Intraperitoneal glucose tolerance was impaired following combined L cell and α-cell loss and normal following α-cell loss. Oral glucose tolerance was improved following L cell and α-cell loss and supernormal following α-cell loss. We present two mouse models that allow studies of the effects of K cell or L cell and α-cell loss as well as isolated α-cell loss. Our findings show that intraperitoneal glucose tolerance is dependent on an intact L cell mass and underscore the diabetogenic effects of α-cell signaling. Furthermore, the results suggest that K cells are less involved in acute regulation of mouse glucose metabolism than L cells and α-cells.
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Affiliation(s)
- J Pedersen
- Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.
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38
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Abstract
Glucagon, a peptide hormone secreted from the α-cells of the pancreatic islets, is critical for blood glucose homeostasis. We reviewed the literature and employed a computational systems analysis of intracellular metabolic and electrical regulation of glucagon secretion to better understand these processes. The mathematical model of α-cell metabolic parameters is based on our previous model for pancreatic β-cells. We also formulated an ionic model for action potentials that incorporates Ca ( 2+) , K (+) , Na (+) and Cl (-) currents. Metabolic and ionic models are coupled to the equations describing Ca ( 2+) homeostasis and glucagon secretion that depends on activation of specific voltage-gated Ca ( 2+) channels. Paracrine and endocrine regulations were analyzed with an emphasis on their effects on a hyperpolarization of membrane potential. This general model simulates and gives insight into the mechanisms of regulation of glucagon secretion under a wide range of experimental conditions. We also reviewed and analyzed dysfunctional mechanisms in α-cells to determine key pharmacological targets for modulating glucagon secretion in type 1 and 2 diabetes.
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Affiliation(s)
- Leonid E Fridlyand
- The Kovler Diabetes Center, Departments of Medicine and Pediatrics, The University of Chicago, Chicago, IL, USA.
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39
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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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40
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Kawamori D. [Dysregulation of glucagon secretion in diabetes and intra-islet insulin effect on alpha-cells]. Nihon Rinsho 2012; 70 Suppl 3:212-217. [PMID: 22768522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Affiliation(s)
- Dan Kawamori
- Department of Metabolic Medicine, Graduate School of Medicine/Medical Education Center, Faculty of Medicine, Osaka University
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41
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Sasaoka T. [Perspective of new and future treatment of type 2 diabetes]. Nihon Rinsho 2012; 70 Suppl 3:707-715. [PMID: 22768603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
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42
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Cheng LY, Xu SQ, Zhang WJ. [Effects of alpha cell in islets on beta cell function]. Sheng Li Ke Xue Jin Zhan 2011; 42:394-397. [PMID: 22242412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
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43
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Abstract
Pancreatic islet cell regeneration is considered to be important in the onset and progression of diabetes and as a potential cell therapy. Current hypotheses, largely based on rodent studies, indicate continuous turnover and plasticity of α- and β-cells in adults; cell populations in rodents respond to increased secretory demand in obesity (30-fold β-cell increase) and pregnancy. Turnover and plasticity of islet cells decrease in mice within >1 year. In man, morphometric observations on postmortem pancreas have indicated that the cellular expansion is much smaller than the increased insulin secretion that accompanies obesity. Longevity of β-cells in humans >20-30 years has been shown by (14) C measurements and bromo-deoxyuridine (BrdU) incorporation and there is an age-related decline in the expression of proteins associated with cell division and regeneration including cyclin D3 and PDX-1. Quantitative estimation and mathematical modelling of the longevity marker, cellular lipofuscin body content, in islets of subjects aged 1-84 years indicated an age-related increase and that 97% of the human β-cell population was established by the age of 20. New data show that human α-cell lipofuscin content is less than that seen in β-cells, but the age-related accumulation is similar; lipofuscin-positive (aged) cells form ≥ 95% of the population after 20 years. Increased turnover of cellular organelles such as mitochondria and endoplasmic reticulum could contribute to lipofuscin accumulation with age in long-lived cells. Induction of regeneration of human islet cells will require understanding of the mechanisms associated with age-related senescence.
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Affiliation(s)
- M Cnop
- Laboratory of Experimental Medicine, Université Libre de Bruxelles (ULB), Brussels, Belgium
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44
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Huang YC, Gaisano HY, Leung YM. Electrophysiological identification of mouse islet α-cells: from isolated single α-cells to in situ assessment within pancreas slices. Islets 2011; 3:139-43. [PMID: 21623173 DOI: 10.4161/isl.3.4.16166] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Investigation of α-cells has long been constrained by their scarce population and localization at the islet mantle which exposes α-cells to injury by conventional islet isolation and dispersion to single cells that employ damaging enzymatic and mechanical means. To surmount these limitations, we recently reported employing the pancreas slice preparation which enables highly efficient acute in situ electrophysiological (patch clamp) examination of α-cells within its unperturbed native social environment with preserved paracrine regulation. In this review, we compare the electrophysiological properties of α-cells in these three preparations, and discuss the current view of glucose regulation of α-cells. We discuss current genetic mouse models that flurophore-tagged α-cells (GYY) and β-cells (MIP-GFP) which can reliably identify islet cells to facilitate their study. Combining these strategies should enable future studies directed at the precise assessment of the perturbation in intrinsic and paracrine regulation of α-cells contributing to abnormal glucose homeostasis in diabetes.
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Affiliation(s)
- Ya-Chi Huang
- Institute of Medical Sciences, University of Toronto, Toronto, Canada
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45
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Stefan M, Simmons RA, Bertera S, Trucco M, Esni F, Drain P, Nicholls RD. Global deficits in development, function, and gene expression in the endocrine pancreas in a deletion mouse model of Prader-Willi syndrome. Am J Physiol Endocrinol Metab 2011; 300:E909-22. [PMID: 21343540 PMCID: PMC3093973 DOI: 10.1152/ajpendo.00185.2010] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Prader-Willi syndrome (PWS) is a multisystem disorder caused by genetic loss of function of a cluster of imprinted, paternally expressed genes. Neonatal failure to thrive in PWS is followed by childhood-onset hyperphagia and obesity among other endocrine and behavioral abnormalities. PWS is typically assumed to be caused by an unknown hypothalamic-pituitary dysfunction, but the underlying pathogenesis remains unknown. A transgenic deletion mouse model (TgPWS) has severe failure to thrive, with very low levels of plasma insulin and glucagon in fetal and neonatal life prior to and following onset of progressive hypoglycemia. In this study, we tested the hypothesis that primary deficits in pancreatic islet development or function may play a fundamental role in the TgPWS neonatal phenotype. Major pancreatic islet hormones (insulin, glucagon) were decreased in TgPWS mice, consistent with plasma levels. Immunohistochemical analysis of the pancreas demonstrated disrupted morphology of TgPWS islets, with reduced α- and β-cell mass arising from an increase in apoptosis. Furthermore, in vivo and in vitro studies show that the rate of insulin secretion is significantly impaired in TgPWS β-cells. In TgPWS pancreas, mRNA levels for genes encoding all pancreatic hormones, other secretory factors, and the ISL1 transcription factor are upregulated by either a compensatory response to plasma hormone deficiencies or a primary effect of a deleted gene. Our findings identify a cluster of imprinted genes required for the development, survival, coordinate regulation of genes encoding hormones, and secretory function of pancreatic endocrine cells, which may underlie the neonatal phenotype of the TgPWS mouse model.
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Affiliation(s)
- Mihaela Stefan
- Dept. of Pediatrics, Children's Hospital of Pittsburgh of UPMC, Rangos Research Bldg., 4401 Penn Ave., Pittsburgh, PA 15224, USA
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Ishihara H. [Cross-talk among pancreatic alpha, beta and delta cells stimulated by incretin hormones]. Nihon Rinsho 2011; 69:795-800. [PMID: 21595261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Incretin hormones, GLP-1 and GIP, contribute to whole body glucose homeostasis by modulating secretion of islet hormones, insulin, glucagon and somatostatin. Both GLP-1 and GIP stimulate insulin and somatostatin secretion. While glucagon secretion is stimulated by GIP, GLP-1 suppresses glucagon secretion. The mechanism by which GLP-1 suppresses glucagon secretion seems to include direct action of the hormone on alpha cells and indirect one through activation of beta and delta cells. However, molecular details of these actions still remain elusive.
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Affiliation(s)
- Hisamitsu Ishihara
- Division of Diabetes and Metabolism, Department of Medicine, Nihon University School of Medicine
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Meier JJ, Ueberberg S, Korbas S, Schneider S. Diminished glucagon suppression after β-cell reduction is due to impaired α-cell function rather than an expansion of α-cell mass. Am J Physiol Endocrinol Metab 2011; 300:E717-23. [PMID: 21285404 PMCID: PMC3279300 DOI: 10.1152/ajpendo.00315.2010] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Impaired suppression of glucagon levels after oral glucose or meal ingestion is a hallmark of type 2 diabetes. Whether hyperglucagonemia after a β-cell loss results from a functional upregulation of glucagon secretion or an increase in α-cell mass is yet unclear. CD-1 mice were treated with streptozotocin (STZ) or saline. Pancreatic tissue was collected after 14, 21, and 28 days and examined for α- and β-cell mass and turnover. Intraperitoneal (ip) glucose tolerance tests were performed at day 28 as well as after 12 days of subcutaneous insulin treatment, and glucose, insulin, and glucagon levels were determined. STZ treatment led to fasting and post-challenge hyperglycemia (P < 0.001 vs. controls). Insulin levels increased after glucose injection in controls (P < 0.001) but were unchanged in STZ mice (P = 0.36). Intraperitoneal glucose elicited a 63.1 ± 4.1% glucagon suppression in control mice (P < 0.001), whereas the glucagon suppression was absent in STZ mice (P = 0.47). Insulin treatment failed to normalize glucagon levels. There was a significant inverse association between insulin and glucagon levels after ip glucose ingestion (r(2) = 0.99). β-Cell mass was reduced by ∼75% in STZ mice compared with controls (P < 0.001), whereas α-cell mass remained unchanged (P > 0.05). α-Cell apoptosis (TUNEL) and replication (Ki67) were rather infrequently noticed, with no significant differences between the groups. These studies underline the importance of endogenous insulin for the glucose-induced suppression of glucagon secretion and suggest that the insufficient decline in glucagon levels after glucose administration in diabetes is primarily due to a functional loss of intraislet inhibition of α-cell function rather than an expansion of α-cell mass.
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Affiliation(s)
- Juris J Meier
- Dept. of Internal Medicine I, St. Josef-Hospital, Ruhr-University Bochum, Germany
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Abstract
Pancreatic islet transplantation is an effective treatment for diabetes mellitus. But it is not clear whether α-cell loss during islets isolation could impair the insulin release from β-cell. To unravel this issue, human islets with α-cell deficiency were prepared by prolonged enzyme digestion, as confirmed by immunocytochemistry, immunofluorescence staining and islet insulin/glucagon content analysis. The functions of islets with α-cell deficiency were evaluated in vitro and in vivo. In vitro, human islets with α-cell deficiency exhibited low glucose-induced insulin release compared with intact islets. In islets deficient in α-cells, exogenous glucagon did not alone stimulate insulin release in the absence of glucose, but increased the glucose-induced insulin release in a dose-dependent manner. In intact islets, glucagon did not significantly change the glucose-stimulated insulin secretion. In vivo, transplantation of human islets with α-cell deficiency did not effectively correct hyperglycemia in diabetic C57BL/6 mice. In diabetic nude mice transplanted with islets deficient in α-cells, administration of exogenous glucagon significantly decreased glycemia, while withdrawing glucagon increased glycemic levels as compared with relevant controls. In addition, the survival of diabetic nude mice grafted with islets deficient in α-cells was significantly shorter than the survival of nude mice grafted with intact islets. These results indicated that glucagon-secreting α-cells have an important role in maintaining glucose-stimulated insulin release from β-cells, and that α-cell loss from islets during isolation has a deleterious effect on insulin secretion.
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Affiliation(s)
- Hui Wang
- Graduate School of Peking Union Medical College, Beijing, China
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Abstract
Pancreatic alpha cells synthesize and release glucagon. This hormone along with insulin, preserves blood glucose levels within a physiological range. During low glucose levels, alpha cells exhibit electrical activity related to glucagon secretion. In this paper, we introduce minimal state models for those ionic channels involved in this electrical activity in mice alpha cells. For estimation of model parameters, we use Monte Carlo algorithms to fit steady-state channel currents. Then, we simulate dynamic ionic currents following experimental protocols. Our aims are 1) To understand the individual ionic channel functioning and modulation that could affect glucagon secretion, and 2) To simulate ionic currents actually measured in voltage-clamp alpha-cell experiments in mice. Our estimations indicate that alpha cells are highly permeable to sodium and potassium which mainly manage action potentials. We have also found that our estimated N-type calcium channel population and density in alpha cells is in good agreement to those reported for L-type calcium channels in beta cells. This finding is strongly relevant since both, L-type and N-type calcium channels, play a main role in insulin and glucagon secretion, respectively.
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Affiliation(s)
- Virginia Gonzalez-Velez
- Dept. Ciencias Basicas, Universidad Autonoma Metropolitana Azcapotzalco, Mexico D.F., 02200, Mexico.
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Ramracheya R, Ward C, Shigeto M, Walker JN, Amisten S, Zhang Q, Johnson PR, Rorsman P, Braun M. Membrane potential-dependent inactivation of voltage-gated ion channels in alpha-cells inhibits glucagon secretion from human islets. Diabetes 2010; 59:2198-208. [PMID: 20547976 PMCID: PMC2927942 DOI: 10.2337/db09-1505] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
OBJECTIVE To document the properties of the voltage-gated ion channels in human pancreatic alpha-cells and their role in glucagon release. RESEARCH DESIGN AND METHODS Glucagon release was measured from intact islets. [Ca(2+)](i) was recorded in cells showing spontaneous activity at 1 mmol/l glucose. Membrane currents and potential were measured by whole-cell patch-clamping in isolated alpha-cells identified by immunocytochemistry. RESULT Glucose inhibited glucagon secretion from human islets; maximal inhibition was observed at 6 mmol/l glucose. Glucagon secretion at 1 mmol/l glucose was inhibited by insulin but not by ZnCl(2). Glucose remained inhibitory in the presence of ZnCl(2) and after blockade of type-2 somatostatin receptors. Human alpha-cells are electrically active at 1 mmol/l glucose. Inhibition of K(ATP)-channels with tolbutamide depolarized alpha-cells by 10 mV and reduced the action potential amplitude. Human alpha-cells contain heteropodatoxin-sensitive A-type K(+)-channels, stromatoxin-sensitive delayed rectifying K(+)-channels, tetrodotoxin-sensitive Na(+)-currents, and low-threshold T-type, isradipine-sensitive L-type, and omega-agatoxin-sensitive P/Q-type Ca(2+)-channels. Glucagon secretion at 1 mmol/l glucose was inhibited by 40-70% by tetrodotoxin, heteropodatoxin-2, stromatoxin, omega-agatoxin, and isradipine. The [Ca(2+)](i) oscillations depend principally on Ca(2+)-influx via L-type Ca(2+)-channels. Capacitance measurements revealed a rapid (<50 ms) component of exocytosis. Exocytosis was negligible at voltages below -20 mV and peaked at 0 mV. Blocking P/Q-type Ca(2+)-currents abolished depolarization-evoked exocytosis. CONCLUSIONS Human alpha-cells are electrically excitable, and blockade of any ion channel involved in action potential depolarization or repolarization results in inhibition of glucagon secretion. We propose that voltage-dependent inactivation of these channels underlies the inhibition of glucagon secretion by tolbutamide and glucose.
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Affiliation(s)
- Reshma Ramracheya
- Oxford Centre for Diabetes Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK.
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