1
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Holst JJ. GLP-1 physiology in obesity and development of incretin-based drugs for chronic weight management. Nat Metab 2024:10.1038/s42255-024-01113-9. [PMID: 39160334 DOI: 10.1038/s42255-024-01113-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Accepted: 07/17/2024] [Indexed: 08/21/2024]
Abstract
The introduction of the highly potent incretin receptor agonists semaglutide and tirzepatide has marked a new era in the treatment of type 2 diabetes and obesity. With normalisation of glycated haemoglobin levels and weight losses around 15-25%, therapeutic goals that were previously unrealistic are now within reach, and clinical trials have documented that these effects are associated with reduced risk of cardiovascular events and premature mortality. Here, I review this remarkable development from the earliest observations of glucose lowering and modest weight losses with native glucagon-like peptide (GLP)-1 and short acting compounds, to the recent development of highly active formulations and new molecules. I will classify these agents as GLP-1-based therapies in the understanding that these compounds or combinations may have actions on other receptors as well. The physiology of GLP-1 is discussed as well as its mechanisms of actions in obesity, in particular, the role of sensory afferents and GLP-1 receptors in the brain. I provide details regarding the development of GLP-1 receptor agonists for anti-obesity therapy and discuss the possible mechanism behind their beneficial effects on adverse cardiovascular events. Finally, I highlight new pharmacological developments, including oral agents, and discuss important questions regarding maintenance therapy.
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Affiliation(s)
- Jens Juul Holst
- Novo Nordisk Foundation Center for Basic Metabolic Research and Department of Biomedical Sciences. Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.
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2
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Teitelman G. A Controversy Regarding the Identity of the Enzyme That Mediates Glucagon-Like Peptide 1 Synthesis in Human Alpha Cells. J Histochem Cytochem 2024; 72:545-550. [PMID: 39248433 PMCID: PMC11425746 DOI: 10.1369/00221554241274879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2024] [Accepted: 06/19/2024] [Indexed: 09/10/2024] Open
Abstract
Processing of proglucagon into glucagon-like peptide-1 (GLP-1) and GLP-2 in intestinal L cells is mediated by the prohormone convertase 1/3 (PC1/3) while PC2 is responsible for the synthesis of glucagon in pancreatic alpha cells. While GLP-1 is also produced by alpha cells, the identity of the convertase involved in its synthesis is still unsettled. It also remains to be determined whether all alpha cells produce the incretin. The aims of this study were first, to elucidate the identity of the proconvertase responsible for GLP-1 production in human alpha cells, and second, to ascertain whether the number of glucagon cells expressing GLP-1 increase during diabetes. To answer these questions, sections of pancreas from donors' non-diabetic controls, type 1 and type 2 diabetes were processed for double-labelled immunostaining of glucagon and GLP-1 and of each hormone and either PC1 or PC2. Stained sections were examined by confocal microscopy. It was found that all alpha cells of islets from those three groups expressed GLP-1 and PC2 but not PC1/3. This observation supports the view that PC2 is the convertase involved in GLP-1 synthesis in all human glucagon cells and suggests that the regulation of its activity may have important clinical application in diabetes.
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3
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Winther-Sørensen M, Garcia SL, Bartholdy A, Ottenheijm ME, Banasik K, Brunak S, Sørensen CM, Gluud LL, Knop FK, Holst JJ, Rosenkilde MM, Jensen MK, Wewer Albrechtsen NJ. Determinants of plasma levels of proglucagon and the metabolic impact of glucagon receptor signalling: a UK Biobank study. Diabetologia 2024; 67:1602-1615. [PMID: 38705923 PMCID: PMC11343844 DOI: 10.1007/s00125-024-06160-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Accepted: 03/13/2024] [Indexed: 05/07/2024]
Abstract
AIMS/HYPOTHESES Glucagon and glucagon-like peptide-1 (GLP-1) are derived from the same precursor; proglucagon, and dual agonists of their receptors are currently being explored for the treatment of obesity and metabolic dysfunction-associated steatotic liver disease (MASLD). Elevated levels of endogenous glucagon (hyperglucagonaemia) have been linked with hyperglycaemia in individuals with type 2 diabetes but are also observed in individuals with obesity and MASLD. GLP-1 levels have been reported to be largely unaffected or even reduced in similar conditions. We investigated potential determinants of plasma proglucagon and associations of glucagon receptor signalling with metabolic diseases based on data from the UK Biobank. METHODS We used exome sequencing data from the UK Biobank for ~410,000 white participants to identify glucagon receptor variants and grouped them based on their known or predicted signalling. Data on plasma levels of proglucagon estimated using Olink technology were available for a subset of the cohort (~40,000). We determined associations of glucagon receptor variants and proglucagon with BMI, type 2 diabetes and liver fat (quantified by liver MRI) and performed survival analyses to investigate if elevated proglucagon predicts type 2 diabetes development. RESULTS Obesity, MASLD and type 2 diabetes were associated with elevated plasma levels of proglucagon independently of each other. Baseline proglucagon levels were associated with the risk of type 2 diabetes development over a 14 year follow-up period (HR 1.13; 95% CI 1.09, 1.17; n=1562; p=1.3×10-12). This association was of the same magnitude across strata of BMI. Carriers of glucagon receptor variants with reduced cAMP signalling had elevated levels of proglucagon (β 0.847; 95% CI 0.04, 1.66; n=17; p=0.04), and carriers of variants with a predicted frameshift mutation had higher levels of liver fat compared with the wild-type reference group (β 0.504; 95% CI 0.03, 0.98; n=11; p=0.04). CONCLUSIONS/INTERPRETATION Our findings support the suggestion that glucagon receptor signalling is involved in MASLD, that plasma levels of proglucagon are linked to the risk of type 2 diabetes development, and that proglucagon levels are influenced by genetic variation in the glucagon receptor, obesity, type 2 diabetes and MASLD. Determining the molecular signalling pathways downstream of glucagon receptor activation may guide the development of biased GLP-1/glucagon co-agonist with improved metabolic benefits. DATA AVAILABILITY All coding is available through https://github.com/nicwin98/UK-Biobank-GCG.
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Affiliation(s)
- Marie Winther-Sørensen
- Department for Clinical Biochemistry, Copenhagen University Hospital - Bispebjerg and Frederiksberg, University of Copenhagen, Copenhagen, Denmark
- Novo Nordisk Foundation Center for Protein 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
| | - Sara L Garcia
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Andreas Bartholdy
- Section of Epidemiology, Department of Public Health, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Maud E Ottenheijm
- Department for Clinical Biochemistry, Copenhagen University Hospital - Bispebjerg and Frederiksberg, University of Copenhagen, Copenhagen, Denmark
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Karina Banasik
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Søren Brunak
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Charlotte M Sørensen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Lise Lotte Gluud
- Gastro Unit, Copenhagen University Hospital - Hvidovre, Hvidovre, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Filip K Knop
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Steno Diabetes Center Copenhagen, Herlev, Denmark
- Center for Clinical Metabolic Research, Gentofte Hospital, University of Copenhagen, Hellerup, 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
| | - Mette M Rosenkilde
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Majken K Jensen
- Section of Epidemiology, Department of Public Health, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Nicolai J Wewer Albrechtsen
- Department for Clinical Biochemistry, Copenhagen University Hospital - Bispebjerg and Frederiksberg, University of Copenhagen, Copenhagen, Denmark.
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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4
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van Albada ME, Shah P, Derks TGJ, Fuchs S, Jans JJM, McLin V, van der Doef HPJ. Abnormal glucose homeostasis and fasting intolerance in patients with congenital porto-systemic shunts. Front Endocrinol (Lausanne) 2023; 14:1190473. [PMID: 37664849 PMCID: PMC10471981 DOI: 10.3389/fendo.2023.1190473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Accepted: 08/04/2023] [Indexed: 09/05/2023] Open
Abstract
In physiological glucose homeostasis, the liver plays a crucial role in the extraction of glucose from the portal circulation and storage as glycogen to enable release through glycogenolysis upon fasting. In addition, insulin secreted by the pancreas is partly eliminated from the systemic circulation by hepatic first-pass. Therefore, patients with a congenital porto-systemic shunt present a unique combination of (a) postabsorptive hyperinsulinemic hypoglycaemia (HH) because of decreased insulin elimination and (b) fasting (ketotic) hypoglycaemia because of decreased glycogenolysis. Patients with porto-systemic shunts therefore provide important insight into the role of the portal circulation and hepatic function in different phases of glucose homeostasis.
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Affiliation(s)
- Mirjam E. van Albada
- Department of Pediatric Endocrinology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Pratik Shah
- Department of Pediatric Endocrinology, The Royal London Childrens Hospital, Barts Health National Health Service (NHS) Trust and William Harvey Research Institute, Queen Mary University London, London, United Kingdom
| | - Terry G. J. Derks
- Department of Metabolic Diseases, Beatrix Children’s Hospital, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Sabine Fuchs
- Department of Metabolic Diseases, Wilhelmina Children’s Hospital, University Medical Center Utrecht, Utrecht, Netherlands
| | - Judith J. M. Jans
- Department of Genetics, Section Metabolic Diagnostics, University Medical Center Utrecht, Utrecht, Netherlands
| | - Valérie McLin
- Swiss Pediatric Liver Center, Department of Pediatrics, Obstetrics, and Gynecology, University of Geneva, Geneva, Switzerland
| | - Hubert P. J. van der Doef
- Department of Pediatric Gastroenterology and Hepatology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
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5
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Pettway YD, Saunders DC, Brissova M. The human α cell in health and disease. J Endocrinol 2023; 258:e220298. [PMID: 37114672 PMCID: PMC10428003 DOI: 10.1530/joe-22-0298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 04/27/2023] [Indexed: 04/29/2023]
Abstract
In commemoration of 100 years since the discovery of glucagon, we review current knowledge about the human α cell. Alpha cells make up 30-40% of human islet endocrine cells and play a major role in regulating whole-body glucose homeostasis, largely through the direct actions of their main secretory product - glucagon - on peripheral organs. Additionally, glucagon and other secretory products of α cells, namely acetylcholine, glutamate, and glucagon-like peptide-1, have been shown to play an indirect role in the modulation of glucose homeostasis through autocrine and paracrine interactions within the islet. Studies of glucagon's role as a counterregulatory hormone have revealed additional important functions of the α cell, including the regulation of multiple aspects of energy metabolism outside that of glucose. At the molecular level, human α cells are defined by the expression of conserved islet-enriched transcription factors and various enriched signature genes, many of which have currently unknown cellular functions. Despite these common threads, notable heterogeneity exists amongst human α cell gene expression and function. Even greater differences are noted at the inter-species level, underscoring the importance of further study of α cell physiology in the human context. Finally, studies on α cell morphology and function in type 1 and type 2 diabetes, as well as other forms of metabolic stress, reveal a key contribution of α cell dysfunction to dysregulated glucose homeostasis in disease pathogenesis, making targeting the α cell an important focus for improving treatment.
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Affiliation(s)
- Yasminye D. Pettway
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, 37232, USA
| | - Diane C. Saunders
- Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, 37232, USA
| | - Marcela Brissova
- Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, 37232, USA
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Wibawa IDN, Mariadi IK, Somayana G, Krisnawardani Kumbara CIY, Sindhughosa DA. Diabetes and fatty liver: Involvement of incretin and its benefit for fatty liver management. World J Diabetes 2023; 14:549-559. [PMID: 37273247 PMCID: PMC10237000 DOI: 10.4239/wjd.v14.i5.549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2022] [Revised: 02/02/2023] [Accepted: 04/11/2023] [Indexed: 05/15/2023] Open
Abstract
Fatty liver disease is defined as liver condition characterized by hepatic steatosis, closely related to pathological conditions in type 2 diabetes and obesity. The high prevalence of fatty liver disease in obese patients with type 2 diabetes reached 70%, reflecting the importance of these conditions with fatty liver. Although the exact pathological mechanism of fatty liver disease, specifically non-alcoholic fatty liver disease (NAFLD) remains not completely revealed, insulin resistance is suggested as the major mechanism that bridged the development of NAFLD. Indeed, loss of the incretin effect leads to insulin resistance. Since incretin is closely related to insulin resistance and the resistance of insulin associated with the development of fatty liver disease, this pathway suggested a potential me-chanism that explains the association between type 2 diabetes and NAFLD. Furthermore, recent studies indicated that NAFLD is associated with impaired glucagon-like peptide-1, resulting in decreased incretin effect. Nevertheless, improving the incretin effect becomes a reasonable approach to manage fatty liver disease. This review elucidates the involvement of incretin in fatty liver disease and recent studies of incretin as the management for fatty liver disease.
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Affiliation(s)
- I Dewa Nyoman Wibawa
- Department of Internal Medicine, Gastroentero-hepatology Division, Udayana University, Faculty of Medicine, Denpasar 80233, Bali, Indonesia
| | - I Ketut Mariadi
- Department of Internal Medicine, Gastroentero-hepatology Division, Udayana University, Faculty of Medicine, Denpasar 80233, Bali, Indonesia
| | - Gde Somayana
- Department of Internal Medicine, Gastroentero-hepatology Division, Udayana University, Faculty of Medicine, Denpasar 80233, Bali, Indonesia
| | | | - Dwijo Anargha Sindhughosa
- Internal Medicine Resident, Udayana University, Faculty of Medicine, Denpasar 80233, Bali, Indonesia
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7
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Development of a selective, sensitive and robust oxyntomodulin dual monoclonal antibody immunoassay. Bioanalysis 2022; 14:1229-1239. [DOI: 10.4155/bio-2022-0084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Background & Aim: Oxyntomodulin (Oxm) is a proglucagon-derived peptide agonist of both the GLP-1 and glucagon receptors and is a key regulator of gastric acid secretion and energy expenditure. Differential processing from proglucagon hinders assay immunoassay selectivity. Method & results: Antibody engineering was used to develop a sandwich immunoassay that selectively measures endogenous Oxm. The pre- and postprandial levels of Oxm from 19 healthy individuals over the course of 2 h were measured. Postprandial increases in Oxm occurred within minutes and levels significantly correlated with those obtained using previously published mass spectrometry assays. Conclusion: This sandwich immunoassay is appropriately sensitive and selective and is also amenable to high-throughput application for the reliable determination of endogenous levels of intact Oxm from human samples.
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8
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Holter MM, Saikia M, Cummings BP. Alpha-cell paracrine signaling in the regulation of beta-cell insulin secretion. Front Endocrinol (Lausanne) 2022; 13:934775. [PMID: 35957816 PMCID: PMC9360487 DOI: 10.3389/fendo.2022.934775] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 06/28/2022] [Indexed: 01/14/2023] Open
Abstract
As an incretin hormone, glucagon-like peptide 1 (GLP-1) lowers blood glucose levels by enhancing glucose-stimulated insulin secretion from pancreatic beta-cells. Therapies targeting the GLP-1 receptor (GLP-1R) use the classical incretin model as a physiological framework in which GLP-1 secreted from enteroendocrine L-cells acts on the beta-cell GLP-1R. However, this model has come into question, as evidence demonstrating local, intra-islet GLP-1 production has advanced the competing hypothesis that the incretin activity of GLP-1 may reflect paracrine signaling of GLP-1 from alpha-cells on GLP-1Rs on beta-cells. Additionally, recent studies suggest that alpha-cell-derived glucagon can serve as an additional, albeit less potent, ligand for the beta-cell GLP-1R, thereby expanding the role of alpha-cells beyond that of a counterregulatory cell type. Efforts to understand the role of the alpha-cell in the regulation of islet function have revealed both transcriptional and functional heterogeneity within the alpha-cell population. Further analysis of this heterogeneity suggests that functionally distinct alpha-cell subpopulations display alterations in islet hormone profile. Thus, the role of the alpha-cell in glucose homeostasis has evolved in recent years, such that alpha-cell to beta-cell communication now presents a critical axis regulating the functional capacity of beta-cells. Herein, we describe and integrate recent advances in our understanding of the impact of alpha-cell paracrine signaling on insulin secretory dynamics and how this intra-islet crosstalk more broadly contributes to whole-body glucose regulation in health and under metabolic stress. Moreover, we explore how these conceptual changes in our understanding of intra-islet GLP-1 biology may impact our understanding of the mechanisms of incretin-based therapeutics.
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Affiliation(s)
- Marlena M. Holter
- Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, United States
- *Correspondence: Marlena M. Holter,
| | - Mridusmita Saikia
- Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, United States
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, United States
| | - Bethany P. Cummings
- School of Medicine, Department of Surgery, Center for Alimentary and Metabolic Sciences, University of California, Davis, Sacramento, CA, United States
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9
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Flatt PR, Knop FK, Tarasov AI. Editorial: Proglucagon-Derived Peptides. Front Endocrinol (Lausanne) 2021; 12:776871. [PMID: 34858346 PMCID: PMC8631785 DOI: 10.3389/fendo.2021.776871] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 10/08/2021] [Indexed: 11/18/2022] Open
Affiliation(s)
- Peter R. Flatt
- School Biomedical Sciences, Ulster University, Coleraine, Northern Ireland, United Kingdom
| | - Filip K. Knop
- Center for Clinical Metabolic Research, Gentofte Hospital, University of Copenhagen, Hellerup, Denmark
- Steno Diabetes Center Copenhagen, Gentofte, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Andrei I. Tarasov
- School Biomedical Sciences, Ulster University, Coleraine, Northern Ireland, United Kingdom
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10
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Asadi F, Dhanvantari S. Pathways of Glucagon Secretion and Trafficking in the Pancreatic Alpha Cell: Novel Pathways, Proteins, and Targets for Hyperglucagonemia. Front Endocrinol (Lausanne) 2021; 12:726368. [PMID: 34659118 PMCID: PMC8511682 DOI: 10.3389/fendo.2021.726368] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 09/13/2021] [Indexed: 12/15/2022] Open
Abstract
Patients with diabetes mellitus exhibit hyperglucagonemia, or excess glucagon secretion, which may be the underlying cause of the hyperglycemia of diabetes. Defective alpha cell secretory responses to glucose and paracrine effectors in both Type 1 and Type 2 diabetes may drive the development of hyperglucagonemia. Therefore, uncovering the mechanisms that regulate glucagon secretion from the pancreatic alpha cell is critical for developing improved treatments for diabetes. In this review, we focus on aspects of alpha cell biology for possible mechanisms for alpha cell dysfunction in diabetes: proglucagon processing, intrinsic and paracrine control of glucagon secretion, secretory granule dynamics, and alterations in intracellular trafficking. We explore possible clues gleaned from these studies in how inhibition of glucagon secretion can be targeted as a treatment for diabetes mellitus.
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Affiliation(s)
- Farzad Asadi
- Department of Pathology and Laboratory Medicine, Western University, London, ON, Canada
- Program in Metabolism and Diabetes, Lawson Health Research Institute, London, ON, Canada
| | - Savita Dhanvantari
- Department of Pathology and Laboratory Medicine, Western University, London, ON, Canada
- Program in Metabolism and Diabetes, Lawson Health Research Institute, London, ON, Canada
- Imaging Research Program, Lawson Health Research Institute, London, ON, Canada
- Department of Medical Biophysics, Western University, London, ON, Canada
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11
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Nogueiras R. MECHANISMS IN ENDOCRINOLOGY: The gut-brain axis: regulating energy balance independent of food intake. Eur J Endocrinol 2021; 185:R75-R91. [PMID: 34260412 PMCID: PMC8345901 DOI: 10.1530/eje-21-0277] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 07/14/2021] [Indexed: 12/15/2022]
Abstract
Obesity is a global pandemic with a large health and economic burden worldwide. Bodyweight is regulated by the ability of the CNS, and especially the hypothalamus, to orchestrate the function of peripheral organs that play a key role in metabolism. Gut hormones play a fundamental role in the regulation of energy balance, as they modulate not only feeding behavior but also energy expenditure and nutrient partitioning. This review examines the recent discoveries about hormones produced in the stomach and gut, which have been reported to regulate food intake and energy expenditure in preclinical models. Some of these hormones act on the hypothalamus to modulate thermogenesis and adiposity in a food intake-independent fashion. Finally, the association of these gut hormones to eating, energy expenditure, and weight loss after bariatric surgery in humans is discussed.
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Affiliation(s)
- Ruben Nogueiras
- Department of Physiology, CIMUS, USC, CIBER Fisiopatología Obesidad y Nutrición (CiberOBN), Instituto Salud Carlos III, Galician Agency of Innovation, Xunta de Galicia, Santiago de Compostela, Spain
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12
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Ramzy A, Kieffer TJ. Altered islet prohormone processing: A cause or consequence of diabetes? Physiol Rev 2021; 102:155-208. [PMID: 34280055 DOI: 10.1152/physrev.00008.2021] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Peptide hormones are first produced as larger precursor prohormones that require endoproteolytic cleavage to liberate the mature hormones. A structurally conserved but functionally distinct family of nine prohormone convertase enzymes (PCs) are responsible for cleavage of protein precursors of which PC1/3 and PC2 are known to be exclusive to neuroendocrine cells and responsible for prohormone cleavage. Differential expression of PCs within tissues define prohormone processing; whereas glucagon is the major product liberated from proglucagon via PC2 in pancreatic α-cells, proglucagon is preferentially processed by PC1/3 in intestinal L cells to produce glucagon-like peptides 1 and 2 (GLP-1, GLP-2). Beyond our understanding of processing of islet prohormones in healthy islets, there is convincing evidence that proinsulin, proIAPP, and proglucagon processing is altered during prediabetes and diabetes. There is predictive value of elevated circulating proinsulin or proinsulin : C-peptide ratio for progression to type 2 diabetes and elevated proinsulin or proinsulin : C-peptide is predictive for development of type 1 diabetes in at risk groups. After onset of diabetes, patients have elevated circulating proinsulin and proIAPP and proinsulin may be an autoantigen in type 1 diabetes. Further, preclinical studies reveal that α-cells have altered proglucagon processing during diabetes leading to increased GLP-1 production. We conclude that despite strong associative data, current evidence is inconclusive on the potential causal role of impaired prohormone processing in diabetes, and suggest that future work should focus on resolving the question of whether altered prohormone processing is a causal driver or merely a consequence of diabetes pathology.
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Affiliation(s)
- Adam Ramzy
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Timothy J Kieffer
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada.,Department of Surgery, University of British Columbia, Vancouver, BC, Canada.,School of Biomedical Engineering, University of British Columbia, Vancouver, BC, Canada
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13
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Guo X, Lv J, Xi R. The specification and function of enteroendocrine cells in Drosophila and mammals: a comparative review. FEBS J 2021; 289:4773-4796. [PMID: 34115929 DOI: 10.1111/febs.16067] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 05/26/2021] [Accepted: 06/09/2021] [Indexed: 12/13/2022]
Abstract
Enteroendocrine cells (EECs) in both invertebrates and vertebrates derive from intestinal stem cells (ISCs) and are scattered along the digestive tract, where they function in sensing various environmental stimuli and subsequently secrete neurotransmitters or neuropeptides to regulate diverse biological and physiological processes. To fulfill these functions, EECs are specified into multiple subtypes that occupy specific gut regions. With advances in single-cell technology, organoid culture experimental systems, and CRISPR/Cas9-mediated genomic editing, rapid progress has been made toward characterization of EEC subtypes in mammals. Additionally, studies of genetic model organisms-especially Drosophila melanogaster-have also provided insights about the molecular processes underlying EEC specification from ISCs and about the establishment of diverse EEC subtypes. In this review, we compare the regulation of EEC specification and function in mammals and Drosophila, with a focus on EEC subtype characterization, on how internal and external regulators mediate EEC subtype specification, and on how EEC-mediated intra- and interorgan communications affect gastrointestinal physiology and pathology.
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Affiliation(s)
- Xingting Guo
- National Institute of Biological Sciences, Beijing, China
| | - Jiaying Lv
- National Institute of Biological Sciences, Beijing, China.,School of Life Sciences, Tsinghua University, Beijing, China
| | - Rongwen Xi
- National Institute of Biological Sciences, Beijing, China.,Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing, China
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14
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Lafferty RA, O’Harte FPM, Irwin N, Gault VA, Flatt PR. Proglucagon-Derived Peptides as Therapeutics. Front Endocrinol (Lausanne) 2021; 12:689678. [PMID: 34093449 PMCID: PMC8171296 DOI: 10.3389/fendo.2021.689678] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 05/05/2021] [Indexed: 12/12/2022] Open
Abstract
Initially discovered as an impurity in insulin preparations, our understanding of the hyperglycaemic hormone glucagon has evolved markedly over subsequent decades. With description of the precursor proglucagon, we now appreciate that glucagon was just the first proglucagon-derived peptide (PGDP) to be characterised. Other bioactive members of the PGDP family include glucagon-like peptides -1 and -2 (GLP-1 and GLP-2), oxyntomodulin (OXM), glicentin and glicentin-related pancreatic peptide (GRPP), with these being produced via tissue-specific processing of proglucagon by the prohormone convertase (PC) enzymes, PC1/3 and PC2. PGDP peptides exert unique physiological effects that influence metabolism and energy regulation, which has witnessed several of them exploited in the form of long-acting, enzymatically resistant analogues for treatment of various pathologies. As such, intramuscular glucagon is well established in rescue of hypoglycaemia, while GLP-2 analogues are indicated in the management of short bowel syndrome. Furthermore, since approval of the first GLP-1 mimetic for the management of Type 2 diabetes mellitus (T2DM) in 2005, GLP-1 therapeutics have become a mainstay of T2DM management due to multifaceted and sustainable improvements in glycaemia, appetite control and weight loss. More recently, longer-acting PGDP therapeutics have been developed, while newfound benefits on cardioprotection, bone health, renal and liver function and cognition have been uncovered. In the present article, we discuss the physiology of PGDP peptides and their therapeutic applications, with a focus on successful design of analogues including dual and triple PGDP receptor agonists currently in clinical development.
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Affiliation(s)
| | | | | | - Victor A. Gault
- School of Biomedical Sciences, Ulster University, Coleraine, United Kingdom
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15
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Aslanoglou D, Bertera S, Sánchez-Soto M, Benjamin Free R, Lee J, Zong W, Xue X, Shrestha S, Brissova M, Logan RW, Wollheim CB, Trucco M, Yechoor VK, Sibley DR, Bottino R, Freyberg Z. Dopamine regulates pancreatic glucagon and insulin secretion via adrenergic and dopaminergic receptors. Transl Psychiatry 2021; 11:59. [PMID: 33589583 PMCID: PMC7884786 DOI: 10.1038/s41398-020-01171-z] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 10/13/2020] [Accepted: 10/26/2020] [Indexed: 01/14/2023] Open
Abstract
Dopamine (DA) and norepinephrine (NE) are catecholamines primarily studied in the central nervous system that also act in the pancreas as peripheral regulators of metabolism. Pancreatic catecholamine signaling has also been increasingly implicated as a mechanism responsible for the metabolic disturbances produced by antipsychotic drugs (APDs). Critically, however, the mechanisms by which catecholamines modulate pancreatic hormone release are not completely understood. We show that human and mouse pancreatic α- and β-cells express the catecholamine biosynthetic and signaling machinery, and that α-cells synthesize DA de novo. This locally-produced pancreatic DA signals via both α- and β-cell adrenergic and dopaminergic receptors with different affinities to regulate glucagon and insulin release. Significantly, we show DA functions as a biased agonist at α2A-adrenergic receptors, preferentially signaling via the canonical G protein-mediated pathway. Our findings highlight the interplay between DA and NE signaling as a novel form of regulation to modulate pancreatic hormone release. Lastly, pharmacological blockade of DA D2-like receptors in human islets with APDs significantly raises insulin and glucagon release. This offers a new mechanism where APDs act directly on islet α- and β-cell targets to produce metabolic disturbances.
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Affiliation(s)
- Despoina Aslanoglou
- grid.21925.3d0000 0004 1936 9000Translational Neuroscience Program, Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA USA
| | - Suzanne Bertera
- grid.417046.00000 0004 0454 5075Institute of Cellular Therapeutics, Allegheny Health Network Research Institute, Allegheny Health Network, Pittsburgh, PA USA
| | - Marta Sánchez-Soto
- grid.94365.3d0000 0001 2297 5165Molecular Neuropharmacology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD USA
| | - R. Benjamin Free
- grid.94365.3d0000 0001 2297 5165Molecular Neuropharmacology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD USA
| | - Jeongkyung Lee
- grid.21925.3d0000 0004 1936 9000Division of Endocrinology, Diabetes & Metabolism, Department of Medicine, Diabetes and Beta Cell Biology Center, University of Pittsburgh, Pittsburgh, PA USA
| | - Wei Zong
- grid.21925.3d0000 0004 1936 9000Department of Biostatistics, University of Pittsburgh, Pittsburgh, PA USA
| | - Xiangning Xue
- grid.21925.3d0000 0004 1936 9000Department of Biostatistics, University of Pittsburgh, Pittsburgh, PA USA
| | - Shristi Shrestha
- grid.412807.80000 0004 1936 9916Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN USA
| | - Marcela Brissova
- grid.412807.80000 0004 1936 9916Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN USA
| | - Ryan W. Logan
- grid.21925.3d0000 0004 1936 9000Translational Neuroscience Program, Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA USA ,grid.249880.f0000 0004 0374 0039Center for Systems Neurogenetics of Addiction, The Jackson Laboratory, Bar Harbor, ME USA
| | - Claes B. Wollheim
- grid.8591.50000 0001 2322 4988Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - Massimo Trucco
- grid.417046.00000 0004 0454 5075Institute of Cellular Therapeutics, Allegheny Health Network Research Institute, Allegheny Health Network, Pittsburgh, PA USA ,grid.147455.60000 0001 2097 0344Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA USA ,grid.166341.70000 0001 2181 3113College of Medicine, Drexel University, Philadelphia, PA USA
| | - Vijay K. Yechoor
- grid.21925.3d0000 0004 1936 9000Division of Endocrinology, Diabetes & Metabolism, Department of Medicine, Diabetes and Beta Cell Biology Center, University of Pittsburgh, Pittsburgh, PA USA
| | - David R. Sibley
- grid.94365.3d0000 0001 2297 5165Molecular Neuropharmacology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD USA
| | - Rita Bottino
- grid.417046.00000 0004 0454 5075Institute of Cellular Therapeutics, Allegheny Health Network Research Institute, Allegheny Health Network, Pittsburgh, PA USA ,grid.147455.60000 0001 2097 0344Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA USA ,grid.166341.70000 0001 2181 3113College of Medicine, Drexel University, Philadelphia, PA USA
| | - Zachary Freyberg
- Translational Neuroscience Program, Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA. .,Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA, USA.
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16
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Saikia M, Holter MM, Donahue LR, Lee IS, Zheng QC, Wise JL, Todero JE, Phuong DJ, Garibay D, Coch R, Sloop KW, Garcia-Ocana A, Danko CG, Cummings BP. GLP-1 receptor signaling increases PCSK1 and β cell features in human α cells. JCI Insight 2021; 6:141851. [PMID: 33554958 PMCID: PMC7934853 DOI: 10.1172/jci.insight.141851] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 12/29/2020] [Indexed: 02/06/2023] Open
Abstract
Glucagon-like peptide-1 (GLP-1) is an incretin hormone that potentiates glucose-stimulated insulin secretion. GLP-1 is classically produced by gut L cells; however, under certain circumstances α cells can express the prohormone convertase required for proglucagon processing to GLP-1, prohormone convertase 1/3 (PC1/3), and can produce GLP-1. However, the mechanisms through which this occurs are poorly defined. Understanding the mechanisms by which α cell PC1/3 expression can be activated may reveal new targets for diabetes treatment. Here, we demonstrate that the GLP-1 receptor (GLP-1R) agonist, liraglutide, increased α cell GLP-1 expression in a β cell GLP-1R-dependent manner. We demonstrate that this effect of liraglutide was translationally relevant in human islets through application of a new scRNA-seq technology, DART-Seq. We found that the effect of liraglutide to increase α cell PC1/3 mRNA expression occurred in a subcluster of α cells and was associated with increased expression of other β cell-like genes, which we confirmed by IHC. Finally, we found that the effect of liraglutide to increase bihormonal insulin+ glucagon+ cells was mediated by the β cell GLP-1R in mice. Together, our data validate a high-sensitivity method for scRNA-seq in human islets and identify a potentially novel GLP-1-mediated pathway regulating human α cell function.
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Affiliation(s)
- Mridusmita Saikia
- Department of Biomedical Sciences and
- Baker Institute for Animal Health, Cornell University College of Veterinary Medicine, Ithaca, New York, USA
| | | | | | | | | | | | | | | | | | - Reilly Coch
- Cayuga Medical Center, Ithaca, New York, USA
| | - Kyle W Sloop
- Diabetes and Complications, Lilly Research Laboratories, Lilly, Indianapolis, Indiana, USA
| | | | - Charles G Danko
- Department of Biomedical Sciences and
- Baker Institute for Animal Health, Cornell University College of Veterinary Medicine, Ithaca, New York, USA
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17
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Hunt JE, Yassin M, Olsen J, Hartmann B, Holst JJ, Kissow H. Intestinal Growth in Glucagon Receptor Knockout Mice Is Not Associated With the Formation of AOM/DSS-Induced Tumors. Front Endocrinol (Lausanne) 2021; 12:695145. [PMID: 34108943 PMCID: PMC8181411 DOI: 10.3389/fendo.2021.695145] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 05/03/2021] [Indexed: 12/22/2022] Open
Abstract
Treatment with exogenous GLP-2 has been shown to accelerate the growth of intestinal adenomas and adenocarcinomas in experimental models of colonic neoplasia, however, the role of endogenous GLP-2 in tumor promotion is less well known. Mice with a global deletion of the glucagon receptor (Gcgr-/-) display an increase in circulating GLP-1 and GLP-2. Due to the intestinotrophic nature of GLP-2, we hypothesized that Gcgr-/- mice would be more susceptible to colonic dysplasia in a model of inflammation-induced colonic carcinogenesis. Female Gcgr-/- mice were first characterized for GLP-2 secretion and in a subsequent study they were given a single injection with the carcinogen azoxymethane (7.5 mg/kg) and treated with dextran sodium sulfate (DSS) (3%) for six days (n=19 and 9). A cohort of animals (n=4) received a colonoscopy 12 days following DSS treatment and all animals were sacrificed after six weeks. Disruption of glucagon receptor signaling led to increased GLP-2 secretion (p<0.0001) and an increased concentration of GLP-2 in the pancreas of Gcgr-/- mice, coinciding with an increase in small intestinal (p<0.0001) and colonic (p<0.05) weight. Increased villus height was recorded in the duodenum (p<0.001) and crypt depth was increased in the duodenum and jejunum (p<0.05 and p<0.05). Disruption of glucagon receptor signaling did not affect body weight during AOM/DSS treatment, neither did it affect the inflammatory score assessed during colonoscopy or the number of large and small adenomas present at the end of the study period. In conclusion, despite the increased endogenous GLP-2 secretion Gcgr-/- mice were not more susceptible to AOM/DSS-induced tumors.
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Affiliation(s)
- Jenna Elizabeth Hunt
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Mohammad Yassin
- Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jørgen Olsen
- Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Bolette Hartmann
- Department of Biomedical Sciences and Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jens Juul Holst
- Department of Biomedical Sciences and Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Hannelouise Kissow
- Department of Biomedical Sciences and Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- *Correspondence: Hannelouise Kissow,
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18
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Galsgaard KD. The Vicious Circle of Hepatic Glucagon Resistance in Non-Alcoholic Fatty Liver Disease. J Clin Med 2020; 9:jcm9124049. [PMID: 33333850 PMCID: PMC7765287 DOI: 10.3390/jcm9124049] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 12/07/2020] [Accepted: 12/08/2020] [Indexed: 02/08/2023] Open
Abstract
A key criterion for the most common chronic liver disease—non-alcoholic fatty liver disease (NAFLD)—is an intrahepatic fat content above 5% in individuals who are not using steatogenic agents or having significant alcohol intake. Subjects with NAFLD have increased plasma concentrations of glucagon, and emerging evidence indicates that subjects with NAFLD may show hepatic glucagon resistance. For many years, glucagon has been thought of as the counterregulatory hormone to insulin with a primary function of increasing blood glucose concentrations and protecting against hypoglycemia. However, in recent years, glucagon has re-emerged as an important regulator of other metabolic processes including lipid and amino acid/protein metabolism. This review discusses the evidence that in NAFLD, hepatic glucagon resistance may result in a dysregulated lipid and amino acid/protein metabolism, leading to excess accumulation of fat, hyperglucagonemia, and increased oxidative stress contributing to the worsening/progression of NAFLD.
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Affiliation(s)
- Katrine D. Galsgaard
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark; ; Tel.: +45-6044-6145
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
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19
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Acosta-Montalvo A, Saponaro C, Kerr-Conte J, Prehn JHM, Pattou F, Bonner C. Proglucagon-Derived Peptides Expression and Secretion in Rat Insulinoma INS-1 Cells. Front Cell Dev Biol 2020; 8:590763. [PMID: 33240888 PMCID: PMC7683504 DOI: 10.3389/fcell.2020.590763] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Accepted: 10/20/2020] [Indexed: 11/26/2022] Open
Abstract
Rat insulinoma INS-1 cells are widely used to study insulin secretory mechanisms. Studies have shown that a population of INS-1 cells are bi-hormonal, co-expressing insulin, and proglucagon proteins. They coined this population as immature cells since they co-secrete proglucagon-derived peptides from the same secretory vesicles similar to that of insulin. Since proglucagon encodes multiple peptides including glucagon, glucagon-like-peptide-1 (GLP-1), GLP-2, oxyntomodulin, and glicentin, their specific expression and secretion are technically challenging. In this study, we aimed to focus on glucagon expression which shares the same amino acid sequence with glicentin and proglucagon. Validation of the anti-glucagon antibody (Abcam) by Western blotting techniques revealed that the antibody detects proglucagon (≈ 20 kDa), glicentin (≈ 9 kDa), and glucagon (≈ 3 kDa) in INS-1 cells and primary islets, all of which were absent in the kidney cell line (HEK293). Using the validated anti-glucagon antibody, we showed by immunofluorescence imaging that a population of INS-1 cells co-express insulin and proglucagon-derived proteins. Furthermore, we found that chronic treatment of INS-1 cells with high-glucose decreases insulin and glucagon content, and also reduces the percentage of bi-hormonal cells. In line with insulin secretion, we found glucagon and glicentin secretion to be induced in a glucose-dependent manner. We conclude that INS-1 cells are a useful model to study glucose-stimulated insulin secretion, but not that of glucagon or glicentin. Our study suggests Western blotting technique as an important tool for researchers to study proglucagon-derived peptides expression and regulation in primary islets in response to various metabolic stimuli.
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Affiliation(s)
- Ana Acosta-Montalvo
- INSERM, U1190, Lille, France.,European Genomic Institute for Diabetes, Lille, France.,University of Lille, Lille, France
| | - Chiara Saponaro
- INSERM, U1190, Lille, France.,European Genomic Institute for Diabetes, Lille, France.,University of Lille, Lille, France
| | - Julie Kerr-Conte
- INSERM, U1190, Lille, France.,European Genomic Institute for Diabetes, Lille, France.,University of Lille, Lille, France
| | - Jochen H M Prehn
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - François Pattou
- INSERM, U1190, Lille, France.,European Genomic Institute for Diabetes, Lille, France.,University of Lille, Lille, France.,Chirurgie Endocrinienne et Métabolique, CHU Lille, Lille, France
| | - Caroline Bonner
- INSERM, U1190, Lille, France.,European Genomic Institute for Diabetes, Lille, France.,University of Lille, Lille, France.,Institut Pasteur de Lille, Lille, France
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20
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Motegi M, Himeno T, Nakai-Shimoda H, Inoue R, Ozeki N, Hayashi Y, Sasajima S, Mohiuddin MS, Asano-Hayami E, Kato M, Asano S, Miura-Yura E, Morishita Y, Kondo M, Tsunekawa S, Kato Y, Kato K, Naruse K, Seino Y, Hayashi Y, Nakamura J, Kamiya H. Deficiency of glucagon gene-derived peptides induces peripheral polyneuropathy in mice. Biochem Biophys Res Commun 2020; 532:47-53. [PMID: 32826056 DOI: 10.1016/j.bbrc.2020.08.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 08/02/2020] [Indexed: 01/25/2023]
Abstract
Although diabetic polyneuropathy (DPN) is the commonest diabetic complication, its pathology remains to be clarified. As previous papers have suggested the neuroprotective effects of glucagon-like peptide-1 in DPN, the current study investigated the physiological indispensability of glucagon gene-derived peptides (GCGDPs) including glucagon-like peptide-1 in the peripheral nervous system (PNS). Neurological functions and neuropathological changes of GCGDP deficient (gcg-/-) mice were examined. The gcg-/- mice showed tactile allodynia and thermal hyperalgesia at 12-18 weeks old, followed by tactile and thermal hypoalgesia at 36 weeks old. Nerve conduction studies revealed a decrease in sensory nerve conduction velocity at 36 weeks old. Pathological findings showed a decrease in intraepidermal nerve fiber densities. Electron microscopy revealed a decrease in circularity and an increase in g-ratio of myelinated fibers and a decrease of unmyelinated fibers in the sural nerves of the gcg-/- mice. Effects of glucagon on neurite outgrowth were examined using an ex vivo culture of dorsal root ganglia. A supraphysiological concentration of glucagon promoted neurite outgrowth. In conclusion, the mice with deficiency of GCGDPs developed peripheral neuropathy with age. Furthermore, glucagon might have neuroprotective effects on the PNS of mice. GCGDPs might be involved in the pathology of DPN.
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Affiliation(s)
- Mikio Motegi
- Division of Diabetes, Department of Internal Medicine, Aichi Medical University School of Medicine, 1-1 Yazakokarimata, Nagakute, Aichi, 480-1195, Japan
| | - Tatsuhito Himeno
- Division of Diabetes, Department of Internal Medicine, Aichi Medical University School of Medicine, 1-1 Yazakokarimata, Nagakute, Aichi, 480-1195, Japan
| | - Hiromi Nakai-Shimoda
- Division of Diabetes, Department of Internal Medicine, Aichi Medical University School of Medicine, 1-1 Yazakokarimata, Nagakute, Aichi, 480-1195, Japan
| | - Rieko Inoue
- Division of Diabetes, Department of Internal Medicine, Aichi Medical University School of Medicine, 1-1 Yazakokarimata, Nagakute, Aichi, 480-1195, Japan
| | - Norio Ozeki
- Division of Diabetes, Department of Internal Medicine, Aichi Medical University School of Medicine, 1-1 Yazakokarimata, Nagakute, Aichi, 480-1195, Japan
| | - Yusuke Hayashi
- Division of Diabetes, Department of Internal Medicine, Aichi Medical University School of Medicine, 1-1 Yazakokarimata, Nagakute, Aichi, 480-1195, Japan
| | - Sachiko Sasajima
- Division of Diabetes, Department of Internal Medicine, Aichi Medical University School of Medicine, 1-1 Yazakokarimata, Nagakute, Aichi, 480-1195, Japan
| | - Mohammad Sarif Mohiuddin
- Division of Diabetes, Department of Internal Medicine, Aichi Medical University School of Medicine, 1-1 Yazakokarimata, Nagakute, Aichi, 480-1195, Japan
| | - Emi Asano-Hayami
- Division of Diabetes, Department of Internal Medicine, Aichi Medical University School of Medicine, 1-1 Yazakokarimata, Nagakute, Aichi, 480-1195, Japan
| | - Makoto Kato
- Division of Diabetes, Department of Internal Medicine, Aichi Medical University School of Medicine, 1-1 Yazakokarimata, Nagakute, Aichi, 480-1195, Japan
| | - Saeko Asano
- Division of Diabetes, Department of Internal Medicine, Aichi Medical University School of Medicine, 1-1 Yazakokarimata, Nagakute, Aichi, 480-1195, Japan
| | - Emiri Miura-Yura
- Division of Diabetes, Department of Internal Medicine, Aichi Medical University School of Medicine, 1-1 Yazakokarimata, Nagakute, Aichi, 480-1195, Japan
| | - Yoshiaki Morishita
- Division of Diabetes, Department of Internal Medicine, Aichi Medical University School of Medicine, 1-1 Yazakokarimata, Nagakute, Aichi, 480-1195, Japan
| | - Masaki Kondo
- Division of Diabetes, Department of Internal Medicine, Aichi Medical University School of Medicine, 1-1 Yazakokarimata, Nagakute, Aichi, 480-1195, Japan
| | - Shin Tsunekawa
- Division of Diabetes, Department of Internal Medicine, Aichi Medical University School of Medicine, 1-1 Yazakokarimata, Nagakute, Aichi, 480-1195, Japan
| | - Yoshiro Kato
- Division of Diabetes, Department of Internal Medicine, Aichi Medical University School of Medicine, 1-1 Yazakokarimata, Nagakute, Aichi, 480-1195, Japan
| | - Koichi Kato
- Laboratory of Medicine, Aichi Gakuin University School of Pharmacy, 1-100 Kusumotocho, Chikusa-ku, Nagoya, Aichi, 464-8650, Japan
| | - Keiko Naruse
- Department of Internal Medicine, Aichi Gakuin University School of Dentistry, 2-11 Suemoridori, Chikusa-ku, Nagoya, Aichi, 464-8651, Japan
| | - Yusuke Seino
- Department of Endocrinology and Metabolism, Fujita Health University School of Medicine, 1-98 Dengakugakubo, Kutsukake-tyo, Toyoake, Aichi, 470-1192, Japan
| | - Yoshitaka Hayashi
- Department of Endocrinology, Division of Stress Adaptation and Recognition, Research Institute of Environmental Medicine, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8601, Japan
| | - Jiro Nakamura
- Division of Diabetes, Department of Internal Medicine, Aichi Medical University School of Medicine, 1-1 Yazakokarimata, Nagakute, Aichi, 480-1195, Japan
| | - Hideki Kamiya
- Division of Diabetes, Department of Internal Medicine, Aichi Medical University School of Medicine, 1-1 Yazakokarimata, Nagakute, Aichi, 480-1195, Japan.
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21
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Lewis JE, Miedzybrodzka EL, Foreman RE, Woodward ORM, Kay RG, Goldspink DA, Gribble FM, Reimann F. Selective stimulation of colonic L cells improves metabolic outcomes in mice. Diabetologia 2020; 63:1396-1407. [PMID: 32342115 PMCID: PMC7286941 DOI: 10.1007/s00125-020-05149-w] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 03/03/2020] [Indexed: 02/07/2023]
Abstract
AIMS/HYPOTHESIS Insulin-like peptide-5 (INSL5) is found only in distal colonic L cells, which co-express glucagon-like peptide-1 (GLP-1) and peptide YY (PYY). GLP-1 is a well-known insulin secretagogue, and GLP-1 and PYY are anorexigenic, whereas INSL5 is considered orexigenic. We aimed to clarify the metabolic impact of selective stimulation of distal colonic L cells in mice. METHODS Insl5 promoter-driven expression of Gq-coupled Designer Receptor Exclusively Activated by Designer Drugs (DREADD) was employed to activate distal colonic L cells (LdistalDq). IPGTT and food intake were assessed with and without DREADD activation. RESULTS LdistalDq cell stimulation with clozapine N-oxide (CNO; 0.3 mg/kg i.p.) increased plasma GLP-1 and PYY (2.67- and 3.31-fold, respectively); INSL5 was not measurable in plasma but was co-secreted with GLP-1 and PYY in vitro. IPGTT (2 g/kg body weight) revealed significantly improved glucose tolerance following CNO injection. CNO-treated mice also exhibited reduced food intake and body weight after 24 h, and increased defecation, the latter being sensitive to 5-hydroxytryptamine (5-HT) receptor 3 inhibition. Pre-treatment with a GLP1 receptor-blocking antibody neutralised the CNO-dependent improvement in glucose tolerance but did not affect the reduction in food intake, and an independent group of animals pair-fed to the CNO-treatment group demonstrated attenuated weight loss. Pre-treatment with JNJ-31020028, a neuropeptide Y receptor type 2 antagonist, abolished the CNO-dependent effect on food intake. Assessment of whole body physiology in metabolic cages revealed LdistalDq cell stimulation increased energy expenditure and increased activity. Acute CNO-induced food intake and glucose homeostasis outcomes were maintained after 2 weeks on a high-fat diet. CONCLUSIONS/INTERPRETATION This proof-of-concept study demonstrates that selective distal colonic L cell stimulation has beneficial metabolic outcomes. Graphical abstract.
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Affiliation(s)
- Jo E Lewis
- Wellcome Trust-MRC Institute of Metabolic Science-Metabolic Research Laboratories, University of Cambridge, Cambridge, CB2 OQQ, UK
| | - Emily L Miedzybrodzka
- Wellcome Trust-MRC Institute of Metabolic Science-Metabolic Research Laboratories, University of Cambridge, Cambridge, CB2 OQQ, UK
| | - Rachel E Foreman
- Wellcome Trust-MRC Institute of Metabolic Science-Metabolic Research Laboratories, University of Cambridge, Cambridge, CB2 OQQ, UK
| | - Orla R M Woodward
- Wellcome Trust-MRC Institute of Metabolic Science-Metabolic Research Laboratories, University of Cambridge, Cambridge, CB2 OQQ, UK
| | - Richard G Kay
- Wellcome Trust-MRC Institute of Metabolic Science-Metabolic Research Laboratories, University of Cambridge, Cambridge, CB2 OQQ, UK
| | - Deborah A Goldspink
- Wellcome Trust-MRC Institute of Metabolic Science-Metabolic Research Laboratories, University of Cambridge, Cambridge, CB2 OQQ, UK
| | - Fiona M Gribble
- Wellcome Trust-MRC Institute of Metabolic Science-Metabolic Research Laboratories, University of Cambridge, Cambridge, CB2 OQQ, UK.
| | - Frank Reimann
- Wellcome Trust-MRC Institute of Metabolic Science-Metabolic Research Laboratories, University of Cambridge, Cambridge, CB2 OQQ, UK.
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22
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Pereira MJ, Thombare K, Sarsenbayeva A, Kamble PG, Almby K, Lundqvist M, Eriksson JW. Direct effects of glucagon on glucose uptake and lipolysis in human adipocytes. Mol Cell Endocrinol 2020; 503:110696. [PMID: 31891768 DOI: 10.1016/j.mce.2019.110696] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 11/25/2019] [Accepted: 12/27/2019] [Indexed: 12/14/2022]
Abstract
We aim to investigate the expression of the glucagon receptor (GCGR) in human adipose tissue, and the impact of glucagon in glucose uptake and lipolysis in human adipocytes. GCGR gene expression in human subcutaneous and visceral adipose tissue was demonstrated, albeit at low levels and with an inter-individual variation. Furthermore, GCGR expression was not significantly different between subjects with T2D and matched controls, and we found no significant association with BMI. Glucagon only at a supra-physiological concentration (10-100 nM) significantly increased basal and insulin-stimulated glucose uptake by up to 1.5-fold. Also, glucagon (0.01 and 1 nM) dose-dependently increased basal and isoproterenol-stimulated lipolysis up to 3.7- and 1.7-fold, respectively, compared to control. In addition, glucagon did not change insulin sensitivity to stimulate glucose uptake or inhibit lipolysis. In conclusion, we show that the GCGR gene is expressed at low levels in human adipose tissue, and glucagon at high concentrations can increase both glucose uptake and lipolysis in human adipocytes. Taken together, our data suggest that glucagon at physiological levels has minor direct effects on the regulation of adipocyte metabolism, but does not antagonize the insulin effect to stimulate glucose uptake and inhibit lipolysis in human adipocytes.
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Affiliation(s)
- Maria J Pereira
- Department of Medical Sciences, Clinical Diabetes and Metabolism, Uppsala University, Uppsala, Sweden.
| | - Ketan Thombare
- Department of Medical Sciences, Clinical Diabetes and Metabolism, Uppsala University, Uppsala, Sweden
| | - Assel Sarsenbayeva
- Department of Medical Sciences, Clinical Diabetes and Metabolism, Uppsala University, Uppsala, Sweden
| | - Prasad G Kamble
- Department of Medical Sciences, Clinical Diabetes and Metabolism, Uppsala University, Uppsala, Sweden
| | - Kristina Almby
- Department of Medical Sciences, Clinical Diabetes and Metabolism, Uppsala University, Uppsala, Sweden
| | - Martin Lundqvist
- Department of Medical Sciences, Clinical Diabetes and Metabolism, Uppsala University, Uppsala, Sweden
| | - Jan W Eriksson
- Department of Medical Sciences, Clinical Diabetes and Metabolism, Uppsala University, Uppsala, Sweden
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Zhang C, Lian A, Xu Y, Jiang Q. Signal Transduction Mechanisms for Glucagon-Induced Somatolactin Secretion and Gene Expression in Nile Tilapia ( Oreochromis niloticus) Pituitary Cells. Front Endocrinol (Lausanne) 2020; 11:629077. [PMID: 33613457 PMCID: PMC7890253 DOI: 10.3389/fendo.2020.629077] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Accepted: 12/23/2020] [Indexed: 11/13/2022] Open
Abstract
Glucagon (GCG) plays a stimulatory role in pituitary hormone regulation, although previous studies have not defined the molecular mechanism whereby GCG affects pituitary hormone secretion. To this end, we identified two distinct proglucagons, Gcga and Gcgb, as well as GCG receptors, Gcgra and Gcgrb, in Nile tilapia (Oreochromis niloticus). Using the cAMP response element (CRE)-luciferase reporter system, tilapia GCGa and GCGb could reciprocally activate the two GCG receptors expressed in human embryonic kidney 293 (HEK293) cells. Quantitative real-time PCR analysis revealed that differential expression of the Gcga and Gcgb and their cognate receptors Gcgra and Gcgrb was found in the various tissues of tilapia. In particular, the Gcgrb is abundantly expressed in the neurointermediate lobe (NIL) of the pituitary gland. In primary cultures of tilapia NIL cells, GCGb effectively stimulated SL release, with parallel rises in the mRNA levels, and co-incubation with the GCG antagonist prevented GCGb-stimulated SL release. In parallel experiments, GCGb treatment dose-dependently enhanced intracellular cyclic adenosine monophosphate (cAMP) accumulation with increasing inositol 1,4,5-trisphosphate (IP3) concentration and the resulting in transient increases of Ca2+ signals in the primary NIL cell culture. Using selective pharmacological approaches, the adenylyl cyclase (AC)/cAMP/protein kinase A (PKA) and phospholipase C (PLC)/IP3/Ca2+/calmodulin (CaM)/CaMK-II pathways were shown to be involved in GCGb-induced SL release and mRNA expression. Together, these results provide evidence for the first time that GCGb can act at the pituitary level to stimulate SL release and gene expression via GCGRb through the activation of the AC/cAMP/PKA and PLC/IP3/Ca2+/CaM/CaMK-II cascades.
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24
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Takahashi N, Chujo D, Kajio H, Ueki K. Contribution of pancreatic α-cell function to insulin sensitivity and glycemic variability in patients with type 1 diabetes. J Diabetes Investig 2019; 10:690-698. [PMID: 30290079 PMCID: PMC6497601 DOI: 10.1111/jdi.12949] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2018] [Revised: 09/18/2018] [Accepted: 09/30/2018] [Indexed: 12/25/2022] Open
Abstract
AIMS/INTRODUCTION To evaluate the contribution of pancreatic α-cell function to the dawn phenomenon, insulin sensitivity, hepatic glucose uptake and glycemic variability in patients with type 1 diabetes. MATERIALS AND METHODS In 40 patients with type 1 diabetes, arginine stimulation tests were carried out, and the area under the curve (AUC) of glucagon was measured using radioimmunoassays (AUCglc RIA ) and enzyme-linked immunosorbent assays (AUCglc ELISA ). The ratio of the insulin dose delivered by an artificial pancreas to maintain euglycemia between 04.00 and 08.00 hours or between 00.00 and 04.00 hours was measured as the dawn index. The glucose infusion rate and hepatic glucose uptake were measured using hyperinsulinemic euglycemic clamp and clamp oral glucose loading tests. Glycemic variability in 96 h was measured by continuous glucose monitoring. RESULTS The median dawn index (1.7, interquartile range 1.0-2.8) was not correlated with AUCglc RIA (R2 = 0.03, P = 0.39) or AUCglc ELISA (R2 = 0.04, P = 0.32). The median glucose infusion rate (7.3 mg/kg/min, interquartile range 6.4-9.2 mg/kg/min) was significantly correlated with AUCglc RIA (R2 = 0.20, P = 0.02) and AUCglc ELISA (R2 = 0.21, P = 0.02). The median hepatic glucose uptake (65.3%, interquartile range 40.0-87.3%) was not correlated with AUCglc RIA (R2 = 0.07, P = 0.26) or AUCglc ELISA (R2 = 0.26, P = 0.79). The standard deviation of glucose levels measured by continuous glucose monitoring was significantly correlated with AUCglc RIA (R2 = 0.11, P = 0.049), but not with AUCglc ELISA (R2 = 0.01, P = 0.75). CONCLUSIONS Pancreatic α-cell function contributed to insulin sensitivity in patients with type 1 diabetes.
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Affiliation(s)
- Nobuyuki Takahashi
- Department of Diabetes, Endocrinology, and MetabolismCenter HospitalNational Center for Global Health and MedicineTokyoJapan
- Department of Molecular DiabetologyGraduate School of MedicineThe University of TokyoTokyoJapan
| | - Daisuke Chujo
- Department of Diabetes, Endocrinology, and MetabolismCenter HospitalNational Center for Global Health and MedicineTokyoJapan
| | - Hiroshi Kajio
- Department of Diabetes, Endocrinology, and MetabolismCenter HospitalNational Center for Global Health and MedicineTokyoJapan
| | - Kohjiro Ueki
- Department of Diabetes, Endocrinology, and MetabolismCenter HospitalNational Center for Global Health and MedicineTokyoJapan
- Department of Molecular DiabetologyGraduate School of MedicineThe University of TokyoTokyoJapan
- Diabetes Research CenterResearch InstituteNational Center for Global Health and MedicineTokyoJapan
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25
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Galsgaard KD, Pedersen J, Knop FK, Holst JJ, Wewer Albrechtsen NJ. Glucagon Receptor Signaling and Lipid Metabolism. Front Physiol 2019; 10:413. [PMID: 31068828 PMCID: PMC6491692 DOI: 10.3389/fphys.2019.00413] [Citation(s) in RCA: 108] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2018] [Accepted: 03/26/2019] [Indexed: 01/04/2023] Open
Abstract
Glucagon is secreted from the pancreatic alpha cells upon hypoglycemia and stimulates hepatic glucose production. Type 2 diabetes is associated with dysregulated glucagon secretion, and increased glucagon concentrations contribute to the diabetic hyperglycemia. Antagonists of the glucagon receptor have been considered as glucose-lowering therapy in type 2 diabetes patients, but their clinical applicability has been questioned because of reports of therapy-induced increments in liver fat content and increased plasma concentrations of low-density lipoprotein. Conversely, in animal models, increased glucagon receptor signaling has been linked to improved lipid metabolism. Glucagon acts primarily on the liver and by regulating hepatic lipid metabolism glucagon may reduce hepatic lipid accumulation and decrease hepatic lipid secretion. Regarding whole-body lipid metabolism, it is controversial to what extent glucagon influences lipolysis in adipose tissue, particularly in humans. Glucagon receptor agonists combined with glucagon-like peptide 1 receptor agonists (dual agonists) improve dyslipidemia and reduce hepatic steatosis. Collectively, emerging data support an essential role of glucagon for lipid 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
| | - Jens Pedersen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Cardiology, Nephrology and Endocrinology, Nordsjællands Hospital Hillerød, University of Copenhagen, Hillerød, Denmark
| | - Filip K Knop
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Clinical Metabolic Physiology, Steno Diabetes Center Copenhagen, Gentofte Hospital, Hellerup, Denmark.,Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - 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
| | - Nicolai J Wewer Albrechtsen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Clinical Biochemistry, Rigshospitalet, Copenhagen, Denmark.,Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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26
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Asadi F, Dhanvantari S. Plasticity in the Glucagon Interactome Reveals Novel Proteins That Regulate Glucagon Secretion in α-TC1-6 Cells. Front Endocrinol (Lausanne) 2019; 9:792. [PMID: 30713523 PMCID: PMC6346685 DOI: 10.3389/fendo.2018.00792] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Accepted: 12/17/2018] [Indexed: 12/27/2022] Open
Abstract
Glucagon is stored within the secretory granules of pancreatic alpha cells until stimuli trigger its release. The alpha cell secretory responses to the stimuli vary widely, possibly due to differences in experimental models or microenvironmental conditions. We hypothesized that the response of the alpha cell to various stimuli could be due to plasticity in the network of proteins that interact with glucagon within alpha cell secretory granules. We used tagged glucagon with Fc to pull out glucagon from the enriched preparation of secretory granules in α-TC1-6 cells. Isolation of secretory granules was validated by immunoisolation with Fc-glucagon and immunoblotting for organelle-specific proteins. Isolated enriched secretory granules were then used for affinity purification with Fc-glucagon followed by liquid chromatography/tandem mass spectrometry to identify secretory granule proteins that interact with glucagon. Proteomic analyses revealed a network of proteins containing glucose regulated protein 78 KDa (GRP78) and histone H4. The interaction between glucagon and the ER stress protein GRP78 and histone H4 was confirmed through co-immunoprecipitation of secretory granule lysates, and colocalization immunofluorescence confocal microscopy. Composition of the protein networks was altered at different glucose levels (25 vs. 5.5 mM) and in response to the paracrine inhibitors of glucagon secretion, GABA and insulin. siRNA-mediated silencing of a subset of these proteins revealed their involvement in glucagon secretion in α-TC1-6 cells. Therefore, our results show a novel and dynamic glucagon interactome within α-TC1-6 cell secretory granules. We suggest that variations in the alpha cell secretory response to stimuli may be governed by plasticity in the glucagon "interactome."
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Affiliation(s)
- Farzad Asadi
- Department of Pathology and Laboratory Medicine, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, Canada
| | - Savita Dhanvantari
- Department of Pathology and Laboratory Medicine, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, Canada
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, Canada
- Metabolism, Diabetes and Imaging Programs, Lawson Health Research Institute, London, ON, Canada
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27
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Abstract
Pancreatic alpha cells are generally considered the only source of glucagon secretion in humans. In the 1970s several groups investigating totally pancreatectomised animals reported that glucagon-like immunoreactive material could be detected in the gastrointestinal tract and reopened the question of an extrapancreatic source of glucagon proposed in 1948 when a hyperglycaemic substance was found in the gastrointestinal tract of dogs and rabbits. Nevertheless, over the years, controversy about the existence of extrapancreatic glucagon has flourished as it proved difficult to accurately measure fully processed 29-amino acid glucagon. Recent advances in analytical methods have increased sensitivity and specificity of glucagon assays and, furthermore, technical advances in mass spectrometry-based proteomics have made the detection of low-abundant peptides, such as glucagon, in human plasma more accurate. Here we review new data on extrapancreatic glucagon secretion in the context of historical data and recent analytical breakthroughs. Furthermore, the source, regulation and potential physiological role of extrapancreatic glucagon are discussed and ongoing challenges and knowledge-gaps are outlined.
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Affiliation(s)
- Asger Lund
- Clinical Metabolic Physiology, Steno Diabetes Center Copenhagen, Gentofte Hospital, Hellerup, Denmark; Department of Medicine, Gentofte Hospital, University of Copenhagen, Copenhagen, Denmark.
| | - Filip K Knop
- Clinical Metabolic Physiology, Steno Diabetes Center Copenhagen, Gentofte Hospital, Hellerup, Denmark; Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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28
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Kay RG, Challis BG, Casey RT, Roberts GP, Meek CL, Reimann F, Gribble FM. Peptidomic analysis of endogenous plasma peptides from patients with pancreatic neuroendocrine tumours. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2018; 32:1414-1424. [PMID: 29857350 PMCID: PMC6099210 DOI: 10.1002/rcm.8183] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 05/15/2018] [Accepted: 05/18/2018] [Indexed: 05/04/2023]
Abstract
RATIONALE Diagnosis of pancreatic neuroendocrine tumours requires the study of patient plasma with multiple immunoassays, using multiple aliquots of plasma. The application of mass spectrometry based techniques could reduce the cost and amount of plasma required for diagnosis. METHODS Plasma samples from two patients with pancreatic neuroendocrine tumours were extracted using an established acetonitrile-based plasma peptide enrichment strategy. The circulating peptidome was characterised using nano and high flow rate liquid chromatography/mass spectrometry (LC/MS) analyses. To assess the diagnostic potential of the analytical approach, a large sample batch (68 plasmas) from control subjects, and aliquots from subjects harbouring two different types of pancreatic neuroendocrine tumour (insulinoma and glucagonoma), were analysed using a 10-min LC/MS peptide screen. RESULTS The untargeted plasma peptidomics approach identified peptides derived from the glucagon prohormone, chromogranin A, chromogranin B and other peptide hormones and proteins related to control of peptide secretion. The glucagon prohormone derived peptides that were detected were compared against putative peptides that were identified using multiple antibody pairs against glucagon peptides. Comparison of the plasma samples for relative levels of selected peptides showed clear separation between the glucagonoma and the insulinoma and control samples. CONCLUSIONS The combination of the organic solvent extraction methodology with high flow rate analysis could potentially be used to aid diagnosis and monitor treatment of patients with functioning pancreatic neuroendocrine tumours. However, significant validation will be required before this approach can be clinically applied.
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Affiliation(s)
- Richard G. Kay
- Institute of Metabolic ScienceMetabolic Research LaboratoriesAddenbrooke's Hospital, Hills RoadCambridgeCB2 0QQUK
| | - Benjamin G. Challis
- Institute of Metabolic ScienceWolfson Diabetes and Endocrine CentreAddenbrooke's HospitalCambridgeUK
- IMED Biotech Unit, Clinical Discovery Unit, AstraZenecaUK
| | - Ruth T. Casey
- Institute of Metabolic ScienceWolfson Diabetes and Endocrine CentreAddenbrooke's HospitalCambridgeUK
| | - Geoffrey P. Roberts
- Institute of Metabolic ScienceMetabolic Research LaboratoriesAddenbrooke's Hospital, Hills RoadCambridgeCB2 0QQUK
| | - Claire L. Meek
- Institute of Metabolic ScienceMetabolic Research LaboratoriesAddenbrooke's Hospital, Hills RoadCambridgeCB2 0QQUK
| | - Frank Reimann
- Institute of Metabolic ScienceMetabolic Research LaboratoriesAddenbrooke's Hospital, Hills RoadCambridgeCB2 0QQUK
| | - Fiona M. Gribble
- Institute of Metabolic ScienceMetabolic Research LaboratoriesAddenbrooke's Hospital, Hills RoadCambridgeCB2 0QQUK
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29
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Circulating Glucagon 1-61 Regulates Blood Glucose by Increasing Insulin Secretion and Hepatic Glucose Production. Cell Rep 2018; 21:1452-1460. [PMID: 29117552 PMCID: PMC5695911 DOI: 10.1016/j.celrep.2017.10.034] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 07/01/2017] [Accepted: 10/05/2017] [Indexed: 12/22/2022] Open
Abstract
Glucagon is secreted from pancreatic α cells, and hypersecretion (hyperglucagonemia) contributes to diabetic hyperglycemia. Molecular heterogeneity in hyperglucagonemia is poorly investigated. By screening human plasma using high-resolution-proteomics, we identified several glucagon variants, among which proglucagon 1-61 (PG 1-61) appears to be the most abundant form. PG 1-61 is secreted in subjects with obesity, both before and after gastric bypass surgery, with protein and fat as the main drivers for secretion before surgery, but glucose after. Studies in hepatocytes and in β cells demonstrated that PG 1-61 dose-dependently increases levels of cAMP, through the glucagon receptor, and increases insulin secretion and protein levels of enzymes regulating glycogenolysis and gluconeogenesis. In rats, PG 1-61 increases blood glucose and plasma insulin and decreases plasma levels of amino acids in vivo. We conclude that glucagon variants, such as PG 1-61, may contribute to glucose regulation by stimulating hepatic glucose production and insulin secretion.
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30
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Handgraaf S, Dusaulcy R, Visentin F, Philippe J, Gosmain Y. 17-β Estradiol regulates proglucagon-derived peptide secretion in mouse and human α- and L cells. JCI Insight 2018; 3:98569. [PMID: 29618657 DOI: 10.1172/jci.insight.98569] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 02/28/2018] [Indexed: 01/11/2023] Open
Abstract
Clinical and experimental data indicate a beneficial effect of estrogens on energy and glucose homeostasis associated with improved insulin sensitivity and positive effects on insulin secretion. The aim of the study was to investigate the impact of estrogens on proglucagon-producing cells, pancreatic α cells, and enteroendocrine L cells. The consequences of sexual hormone deprivation were evaluated in ovariectomized mice (ovx). Ovx mice exhibited impaired glucose tolerance during oral glucose tolerance tests (OGTT), which was associated with decreased GLP-1 intestinal and pancreatic secretion and content, an effect that was reversed by estradiol (E2) treatment. Indeed, E2 increased oral glucose-induced GLP-1 secretion in vivo and GLP-1 secretion from primary culture of mouse and human α cells through the activation of all 3 estrogen receptors (ERs), whereas E2-induced GLP-1 secretion from mouse and human intestinal explants occurred only by ERβ activation. Underlying the implication of ERβ, its selective agonist WAY20070 was able to restore glucose tolerance in ovx mice at least partly through plasma GLP-1 increase. We conclude that E2 directly controls both α- and L cells to increase GLP-1 secretion, in addition to its effects on insulin and glucagon secretion, highlighting the potential beneficial role of the estrogenic pathway and, more particularly, of ERβ agonists to prevent type 2 diabetes.
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31
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Brandt SJ, Götz A, Tschöp MH, Müller TD. Gut hormone polyagonists for the treatment of type 2 diabetes. Peptides 2018; 100:190-201. [PMID: 29412819 PMCID: PMC5805859 DOI: 10.1016/j.peptides.2017.12.021] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 12/21/2017] [Accepted: 12/21/2017] [Indexed: 12/20/2022]
Abstract
Chemical derivatives of the gut-derived peptide hormone glucagon-like peptide 1 (GLP-1) are among the best-in-class pharmacotherapies to treat obesity and type 2 diabetes. However, GLP-1 analogs have modest weight lowering capacity, in the range of 5-10%, and the therapeutic window is hampered by dose-dependent side effects. Over the last few years, a new concept has emerged: combining the beneficial effects of several key metabolic hormones into a single molecular entity. Several unimolecular GLP-1-based polyagonists have shown superior metabolic action compared to GLP-1 monotherapies. In this review article, we highlight the history of polyagonists targeting the receptors for GLP-1, GIP and glucagon, and discuss recent progress in expanding of this concept to now allow targeted delivery of nuclear hormones via GLP-1 and other gut hormones, as a novel approach towards more personalized pharmacotherapies.
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Affiliation(s)
- Sara J Brandt
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center at Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Business Campus Garching, Parkring 13, 85748 Garching, Germany
| | - Anna Götz
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center at Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Business Campus Garching, Parkring 13, 85748 Garching, Germany; Department of Internal Medicine I, University Hospital RWTH Aachen, Aachen, Germany; Institute for Diabetes und Regeneration, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Business Campus Garching, Parkring 13, 85748, Garching, Germany
| | - Matthias H Tschöp
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center at Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Business Campus Garching, Parkring 13, 85748 Garching, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany; Division of Metabolic Diseases, Department of Medicine, Technische Universität München, Munich, Germany
| | - Timo D Müller
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center at Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Business Campus Garching, Parkring 13, 85748 Garching, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany.
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32
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Lee JH, Wen X, Cho H, Koo SH. CREB/CRTC2 controls GLP-1-dependent regulation of glucose homeostasis. FASEB J 2018; 32:1566-1578. [PMID: 29118086 DOI: 10.1096/fj.201700845r] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Glucagon-like peptide 1 (GLP-1) is a major incretin that controls glucose homeostasis. The secretion of mature GLP-1 is regulated via GPCRs, including bile acid receptor G protein-coupled bile acid receptor 1, which uses cAMP signaling to enhance the exocytosis of GLP-1-containing vesicles. However, the role of cAMP-mediated transcription has not been clearly demonstrated to date. In this study, we explored the role of cAMP response element-binding protein/CREB-regulated transcription coactivator 2 (CREB/CRTC2)-dependent transcription on GLP-1 secretion in the L cells. We found that the reduced CREB/CRTC2 activity impaired the cAMP-dependent increase in GLP-1 secretion, whereas expression of constitutively active CRTC2 increased GLP-1 exocytosis from the L cells. Close investigation revealed that expression of not only proglucagon but also PC1/3, an endopeptidase for GLP-1 maturation, is transcriptionally regulated by CREB/CRTC2. Furthermore, expression of peroxisome proliferator-activating receptor coactivator 1 α is also reduced upon depletion of CRTC2, leading to the decreased expression of oxidative phosphorylation (OxPhos) genes, reduced ATP levels, and calcium concentrations in the L cells. Finally, we observed that intestine-specific CRTC2 knockout mice displayed reduced GLP-1 expression, leading to the lower plasma GLP-1 levels, impaired glucose tolerance, and decreased insulin-containing β cells in pancreatic islets. Our data show that the CREB/CRTC2-dependent transcriptional pathway is critical for regulating glucose homeostasis by controlling production of GLP-1 from the L cells at the level of transcription, maturation, and exocytosis.-Lee, J.-H., Wen, X., Cho, H., Koo, S.-H. CREB/CRTC2 controls GLP-1-dependent regulation of glucose homeostasis.
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Affiliation(s)
- Ji-Hyun Lee
- Division of Life Sciences, Korea University, Seoul, Korea
| | - Xianlan Wen
- Department of Physiology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon, Korea
| | - Hana Cho
- Department of Physiology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon, Korea
| | - Seung-Hoi Koo
- Division of Life Sciences, Korea University, Seoul, Korea
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33
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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] [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, Yuan C, Cui YG, Diao FY, Yu MK, Liu JY, Ruan YC, Chan HC. Abnormal CFTR Affects Glucagon Production by Islet α Cells in Cystic Fibrosis and Polycystic Ovarian Syndrome. Front Physiol 2017; 8:835. [PMID: 29204121 PMCID: PMC5698272 DOI: 10.3389/fphys.2017.00835] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 10/09/2017] [Indexed: 12/26/2022] Open
Abstract
Glucagon, produced by islet α cells, functions to increase blood glucose. Abnormal glucose levels are often seen in cystic fibrosis (CF), a systematic disease caused by mutations of the CF transmembrane conductance regulator (CFTR), and in polycystic ovarian syndrome (PCOS), an endocrine disorder featured with hyperandrogenism affecting 5-10% women of reproductive age. Here, we explored the role of CFTR in glucagon production in α cells and its possible contribution to glucagon disturbance in CF and PCOS. We found elevated fasting glucagon levels in CFTR mutant (DF508) mice compared to the wildtypes. Glucagon and prohormone convertase 2 (PC2) were also upregulated in CFTR inhibitor-treated or DF508 islets, as compared to the controls or wildtypes, respectively. Dihydrotestosterone (DHT)-induced PCOS rats exhibited significantly lower fasting glucagon levels with higher CFTR expression in α cells compared to that of controls. Treatment of mouse islets or αTC1-9 cells with DHT enhanced CFTR expression and reduced the levels of glucagon and PC2. The inhibitory effect of DHT on glucagon production was blocked by CFTR inhibitors in mouse islets, and mimicked by overexpressing CFTR in αTC1-9 cells with reduced phosphorylation of the cAMP/Ca2+ response element binding protein (p-CREB), a key transcription factor for glucagon and PC2. These results revealed a previously undefined role of CFTR in suppressing glucagon production in α-cells, defects in which may contribute to glucose metabolic disorder seen in CF and PCOS.
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Affiliation(s)
- Wen Qing Huang
- Epithelial Cell Biology Research Centre, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, Hong Kong
| | - Jing Hui Guo
- Epithelial Cell Biology Research Centre, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, 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, China
| | - Chun Yuan
- State Key Laboratory of Reproductive Medicine, Clinical Center of Reproductive Medicine, First Affiliated Hospital, Nanjing Medical University, Nanjing, China
| | - Yu Gui Cui
- State Key Laboratory of Reproductive Medicine, Clinical Center of Reproductive Medicine, First Affiliated Hospital, Nanjing Medical University, Nanjing, China
| | - Fei Yang Diao
- State Key Laboratory of Reproductive Medicine, Clinical Center of Reproductive Medicine, First Affiliated Hospital, Nanjing Medical University, Nanjing, China
| | - Mei Kuen Yu
- Epithelial Cell Biology Research Centre, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, Hong Kong
- Department of Biomedical Engineering, Faculty of Engineering, The Hong Kong Polytechnic University, Hong Kong, Hong Kong
| | - Jia Yin Liu
- State Key Laboratory of Reproductive Medicine, Clinical Center of Reproductive Medicine, First Affiliated Hospital, Nanjing Medical University, Nanjing, China
| | - Ye Chun Ruan
- Epithelial Cell Biology Research Centre, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, Hong Kong
- Department of Biomedical Engineering, Faculty of Engineering, The Hong Kong Polytechnic University, Hong Kong, Hong Kong
| | - Hsiao Chang Chan
- Epithelial Cell Biology Research Centre, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, Hong Kong
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Abstract
Peptide hormones represent a major class of hormones that are made from amino acids by specialized endocrine glands. The maturation of bioactive hormones take place in the rough endoplasmic reticulum and Golgi apparatus, where preprohormones are proteolytically cleaved into prohormones, and subsequently into mature peptide hormones. Once the bioactive hormones are released into the circulation, they interact with receptors located on the plasma membrane of target cells, and initiate intracellular signaling pathways to regulate physiological processes including energy metabolism, growth, stress, and reproduction. However, excessive amount of circulating peptide hormones often associates with the presence of tumors. Section 2 discusses 10 peptide hormones as tumor markers and their clinical application in aiding the diagnosis of tumors as well as monitoring the disease process.
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Affiliation(s)
- Qian Sun
- National Institutes of Health, Bethesda, MD, United States
| | - Zhen Zhao
- National Institutes of Health, Bethesda, MD, United States.
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36
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Modified Western blotting for insulin and other diabetes-associated peptide hormones. Sci Rep 2017; 7:6949. [PMID: 28761041 PMCID: PMC5537366 DOI: 10.1038/s41598-017-04456-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Accepted: 05/03/2017] [Indexed: 12/16/2022] Open
Abstract
Now, the quantification of proinsulin/insulin contents within organisms tends to be evaluated only by enzyme-linked immunosorbent assay (ELISA), although assessing the adequacy of results by some quantification method is important. Remarkably, few scientific papers use detection by Western blotting (WB), another immunological assay, of proinsulin/insulin. We found two problems with quantification of insulin and proinsulin by general WB: the shape of an insulin band in gel electrophoresis is distorted, and the retention potency to a blotting membrane of the peptide hormones (mainly insulin) is low. We solved the first problem by optimizing the sodium dodecyl sulfate concentration in the sample buffer and the second problem by glutaraldehyde fixation following treatment with a blocking solution for a short time. The improvements were confirmed by quantification of proinsulin/insulin in standards, MIN6c4 cell lysates, and MIN6c4 culture supernatants. Furthermore, we showed that the modified WB is applicable to other diabetes-associated peptide hormones: insulin analogs, glucagon, GLP-1s, somatostatins, ghrelins, and pancreatic polypeptide. Our data showed that the modified WB can contribute to qualitative or quantitative analyses of diabetes-associated peptides by providing analytical information based on electrophoresis, although ELISA, which is an almost exclusive method in the quantification of peptide hormones, supplies only numerical data.
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Cao T, Yang D, Zhang X, Wang Y, Qiao Z, Gao L, Liang Y, Yu B, Zhang P. FAM3D inhibits glucagon secretion via MKP1-dependent suppression of ERK1/2 signaling. Cell Biol Toxicol 2017; 33:457-466. [PMID: 28247283 DOI: 10.1007/s10565-017-9387-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2016] [Accepted: 02/13/2017] [Indexed: 12/28/2022]
Abstract
Dysregulated glucagon secretion is a hallmark of type 2 diabetes (T2D). To date, few effective therapeutic agents target on deranged glucagon secretion. Family with sequence similarity 3 member D (FAM3D) is a novel gut-derived cytokine-like protein, and its secretion timing is contrary to that of glucagon. However, the roles of FAM3D in metabolic disorder and its biological functions are largely unknown. In the present study, we investigated whether FAM3D modulates glucagon production in mouse pancreatic alpha TC1 clone 6 (αTC1-6) cells. Glucagon secretion, prohormone convertase 2 (PC2) activity, and mitogen-activated protein kinase (MAPK) pathway were assessed. Exogenous FAM3D inhibited glucagon secretion, PC2 activity, as well as extracellular-regulated protein kinase 1/2 (ERK1/2) signaling and induced MAPK phosphatase 1 (MKP1) expression. Moreover, knockdown of MKP1 and inhibition of ERK1/2 abolished and potentiated the inhibitory effect of FAM3D on glucagon secretion, respectively. Taken together, FAM3D inhibits glucagon secretion via MKP1-dependent suppression of ERK1/2 signaling. These results provide rationale for developing the therapeutic potential of FAM3D for dysregulated glucagon secretion and T2D.
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Affiliation(s)
- Ting Cao
- Center for Medical Research and Innovation, Shanghai Pudong Hospital, Fudan University Pudong Medical Center, 2800 Gongwei Road, Pudong, Shanghai, 201399, China
| | - Dan Yang
- Center for Medical Research and Innovation, Shanghai Pudong Hospital, Fudan University Pudong Medical Center, 2800 Gongwei Road, Pudong, Shanghai, 201399, China
| | - Xiong Zhang
- Department of Surgery, Shanghai Pudong Hospital, Fudan University Pudong Medical Center, Shanghai, China
| | - Yueqian Wang
- Center for Medical Research and Innovation, Shanghai Pudong Hospital, Fudan University Pudong Medical Center, 2800 Gongwei Road, Pudong, Shanghai, 201399, China
| | - Zhengdong Qiao
- Center for Medical Research and Innovation, Shanghai Pudong Hospital, Fudan University Pudong Medical Center, 2800 Gongwei Road, Pudong, Shanghai, 201399, China
| | - Lili Gao
- Center for Medical Research and Innovation, Shanghai Pudong Hospital, Fudan University Pudong Medical Center, 2800 Gongwei Road, Pudong, Shanghai, 201399, China
| | - Yongjun Liang
- Center for Medical Research and Innovation, Shanghai Pudong Hospital, Fudan University Pudong Medical Center, 2800 Gongwei Road, Pudong, Shanghai, 201399, China
| | - Bo Yu
- Department of Surgery, Shanghai Pudong Hospital, Fudan University Pudong Medical Center, Shanghai, China.
| | - Peng Zhang
- Center for Medical Research and Innovation, Shanghai Pudong Hospital, Fudan University Pudong Medical Center, 2800 Gongwei Road, Pudong, Shanghai, 201399, China.
- Department of Surgery, Shanghai Pudong Hospital, Fudan University Pudong Medical Center, Shanghai, China.
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Abstract
Objective: To summarize the pharmacology, development, and clinical application of teduglutide (ALX-0600), a glucagon-like peptide-2 (GLP-2) analog for the treatment of short bowel syndrome (SBS). Data Sources: Clinical literature, including both primary sources and review articles, was accessed through a search of the MEDLINE databases (1980–March 2006). Key search terms included teduglutide, ALX-0600, glucagon-like peptide-2, short bowel syndrome, short gut, and intestinal adaptation. Clinical trial and drug data were supplied by the manufacturer, NPS Pharmaceuticals. Study Selection and Data Extraction: Review articles, abstracts, and clinical studies related to GLP-2 and its analog, teduglutide, were analyzed. An evaluation of the research exploring teduglutide for the management of SBS was conducted. Relevant information was then selected. Data Synthesis: Research has revealed that administration of GLP-2 to patients following major small bowel resection improves intestinal adaptation and nutrient absorption. Teduglutide is an enzyme-resistant GLP-2 analog that shows promise in preventing intestinal injury, restoring mucosal integrity, and enhancing intestinal absorptive function. Conclusions: Data from ongoing clinical trials indicate that teduglutide may have the ability to enhance intestinal absorptive capacity in patients with SBS. Further studies and the completion of Phase III trials are necessary to determine the appropriate dosage and length of treatment for patients with SBS to gain optimal therapeutic benefit from this drug.
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Affiliation(s)
- Marcus Ferrone
- Department of Pharmacy; Nutrition Mayo Clinic/St. Luke's Hospital, Jacksonville, FL 32216, USA.
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Fava GE, Dong EW, Wu H. Intra-islet glucagon-like peptide 1. J Diabetes Complications 2016; 30:1651-1658. [PMID: 27267264 PMCID: PMC5050074 DOI: 10.1016/j.jdiacomp.2016.05.016] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2016] [Revised: 05/14/2016] [Accepted: 05/17/2016] [Indexed: 02/06/2023]
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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40
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Sekar R, Singh K, Arokiaraj AWR, Chow BKC. Pharmacological Actions of Glucagon-Like Peptide-1, Gastric Inhibitory Polypeptide, and Glucagon. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2016; 326:279-341. [PMID: 27572131 DOI: 10.1016/bs.ircmb.2016.05.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Glucagon family of peptide hormones is a group of structurally related brain-gut peptides that exert their pleiotropic actions through interactions with unique members of class B1 G protein-coupled receptors (GPCRs). They are key regulators of hormonal homeostasis and are important drug targets for metabolic disorders such as type-2 diabetes mellitus (T2DM), obesity, and dysregulations of the nervous systems such as migraine, anxiety, depression, neurodegeneration, psychiatric disorders, and cardiovascular diseases. The current review aims to provide a detailed overview of the current understanding of the pharmacological actions and therapeutic advances of three members within this family including glucagon-like peptide-1 (GLP-1), gastric inhibitory polypeptide (GIP), and glucagon.
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Affiliation(s)
- R Sekar
- School of Biological Sciences, University of Hong Kong, Hong Kong, China
| | - K Singh
- School of Biological Sciences, University of Hong Kong, Hong Kong, China
| | - A W R Arokiaraj
- School of Biological Sciences, University of Hong Kong, Hong Kong, China
| | - B K C Chow
- School of Biological Sciences, University of Hong Kong, Hong Kong, China.
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41
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Mohan H, Gasner M, Ramesh N, Unniappan S. Ghrelin, ghrelin-O-acyl transferase, nucleobindin-2/nesfatin-1 and prohormone convertases in the pancreatic islets of Sprague Dawley rats during development. J Mol Histol 2016; 47:325-36. [DOI: 10.1007/s10735-016-9673-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2015] [Accepted: 03/29/2016] [Indexed: 12/18/2022]
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Ramos-Molina B, Martin MG, Lindberg I. PCSK1 Variants and Human Obesity. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2016; 140:47-74. [PMID: 27288825 DOI: 10.1016/bs.pmbts.2015.12.001] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
PCSK1, encoding prohormone convertase 1/3 (PC1/3), was one of the first genes linked to monogenic early-onset obesity. PC1/3 is a protease involved in the biosynthetic processing of a variety of neuropeptides and prohormones in endocrine tissues. PC1/3 activity is essential for the activating cleavage of many peptide hormone precursors implicated in the regulation of food ingestion, glucose homeostasis, and energy homeostasis, for example, proopiomelanocortin, proinsulin, proglucagon, and proghrelin. A large number of genome-wide association studies in a variety of different populations have now firmly established a link between three PCSK1 polymorphisms frequent in the population and increased risk of obesity. Human subjects with PC1/3 deficiency, a rare autosomal-recessive disorder caused by the presence of loss-of-function mutations in both alleles, are obese and display a complex set of endocrinopathies. Increasing numbers of genetic diagnoses of infants with persistent diarrhea has recently led to the finding of many novel PCSK1 mutations. PCSK1-deficient infants experience severe intestinal malabsorption during the first years of life, requiring controlled nutrition; these children then become hyperphagic, with associated obesity. The biochemical characterization of novel loss-of-function PCSK1 mutations has resulted in the discovery of new pathological mechanisms affecting the cell biology of the endocrine cell beyond simple loss of enzyme activity, for example, dominant-negative effects of certain mutants on wild-type PC1/3 protein, and activation of the cellular unfolded protein response by endoplasmic reticulum-retained mutants. A better understanding of these molecular and cellular pathologies may illuminate possible treatments for the complex endocrinopathy of PCSK1 deficiency, including obesity.
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Affiliation(s)
- B Ramos-Molina
- Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - M G Martin
- Department of Pediatrics, Division of Gastroenterology and Nutrition, Mattel Children's Hospital and the David Geffen School of Medicine, Los Angeles, CA, United States of America
| | - I Lindberg
- Department of Anatomy and Neurobiology, University of Maryland, Baltimore, MD, United States of America.
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Kumar DP, Asgharpour A, Mirshahi F, Park SH, Liu S, Imai Y, Nadler JL, Grider JR, Murthy KS, Sanyal AJ. Activation of Transmembrane Bile Acid Receptor TGR5 Modulates Pancreatic Islet α Cells to Promote Glucose Homeostasis. J Biol Chem 2016; 291:6626-40. [PMID: 26757816 DOI: 10.1074/jbc.m115.699504] [Citation(s) in RCA: 94] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Indexed: 12/19/2022] Open
Abstract
The physiological role of the TGR5 receptor in the pancreas is not fully understood. We previously showed that activation of TGR5 in pancreatic β cells by bile acids induces insulin secretion. Glucagon released from pancreatic α cells and glucagon-like peptide 1 (GLP-1) released from intestinal L cells regulate insulin secretion. Both glucagon and GLP-1 are derived from alternate splicing of a common precursor, proglucagon by PC2 and PC1, respectively. We investigated whether TGR5 activation in pancreatic α cells enhances hyperglycemia-induced PC1 expression thereby releasing GLP-1, which in turn increases β cell mass and function in a paracrine manner. TGR5 activation augmented a hyperglycemia-induced switch from glucagon to GLP-1 synthesis in human and mouse islet α cells by GS/cAMP/PKA/cAMP-response element-binding protein-dependent activation of PC1. Furthermore, TGR5-induced GLP-1 release from α cells was via an Epac-mediated PKA-independent mechanism. Administration of the TGR5 agonist, INT-777, to db/db mice attenuated the increase in body weight and improved glucose tolerance and insulin sensitivity. INT-777 augmented PC1 expression in α cells and stimulated GLP-1 release from islets of db/db mice compared with control. INT-777 also increased pancreatic β cell proliferation and insulin synthesis. The effect of TGR5-mediated GLP-1 from α cells on insulin release from islets could be blocked by GLP-1 receptor antagonist. These results suggest that TGR5 activation mediates cross-talk between α and β cells by switching from glucagon to GLP-1 to restore β cell mass and function under hyperglycemic conditions. Thus, INT-777-mediated TGR5 activation could be leveraged as a novel way to treat type 2 diabetes mellitus.
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Affiliation(s)
- Divya P Kumar
- Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, Virginia 23298 and
| | | | | | - So Hyun Park
- the Department of Internal Medicine, Strelitz Diabetes Center, Eastern Virginia Medical School, Norfolk, Virginia 23507
| | - Sichen Liu
- the Department of Internal Medicine, Strelitz Diabetes Center, Eastern Virginia Medical School, Norfolk, Virginia 23507
| | - Yumi Imai
- the Department of Internal Medicine, Strelitz Diabetes Center, Eastern Virginia Medical School, Norfolk, Virginia 23507
| | - Jerry L Nadler
- the Department of Internal Medicine, Strelitz Diabetes Center, Eastern Virginia Medical School, Norfolk, Virginia 23507
| | - John R Grider
- Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, Virginia 23298 and
| | - Karnam S Murthy
- Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, Virginia 23298 and
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44
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Matsuo T, Miyagawa JI, Kusunoki Y, Miuchi M, Ikawa T, Akagami T, Tokuda M, Katsuno T, Kushida A, Inagaki T, Namba M. Postabsorptive hyperglucagonemia in patients with type 2 diabetes mellitus analyzed with a novel enzyme-linked immunosorbent assay. J Diabetes Investig 2015; 7:324-31. [PMID: 27330717 PMCID: PMC4847885 DOI: 10.1111/jdi.12400] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Revised: 06/29/2015] [Accepted: 07/09/2015] [Indexed: 01/11/2023] Open
Abstract
Aims/introduction The aims of the present study were to investigate the performance of a novel sandwich enzyme‐linked immunosorbent assay (ELISA) for measuring glucagon (1–29) with monoclonal antibodies against both the C‐ and N‐terminal regions of glucagon (1–29), and to analyze the differences in plasma levels and responses of glucagon (1–29) to oral glucose loading in normal glucose tolerance (NGT) subjects and patients with type 2 diabetes mellitus. Materials and Methods The cross‐reactivity against proglucagon fragments using the ELISA kit and two types of conventional radioimmunoassay (RIA) kits was evaluated. A 75‐g oral glucose tolerance test was carried out with NGT subjects and patients with type 2 diabetes mellitus, and the glucagon (1–29) concentration was measured using three types of kit. Results The ELISA kit clearly had the lowest cross‐reactivity against miniglucagon (19–29) and glicentin (1–61). The oral glucose tolerance test was carried out with 30 NGT and 17 patients with type 2 diabetes mellitus. The glucagon (1–29) levels measured by the ELISA kit after glucose loading were significantly higher at all time‐points in the type 2 diabetes mellitus group than in the NGT group. However, the glucagon (1–29) levels measured by one RIA kit were significantly higher in the NGT group, and those measured with the other RIA kit were approximately the same among the groups. Conclusions The novel sandwich ELISA accurately determines plasma glucagon (1–29) concentrations with much less cross‐reactivity against other proglucagon fragments than conventional RIA kits.
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Affiliation(s)
- Toshihiro Matsuo
- Division of Diabetes, Endocrinology and Metabolism Department of Internal Medicine Hyogo College of Medicine Nishinomiya Hyogo Japan
| | - Jun-Ichiro Miyagawa
- Division of Diabetes, Endocrinology and Metabolism Department of Internal Medicine Hyogo College of Medicine Nishinomiya Hyogo Japan
| | - Yoshiki Kusunoki
- Division of Diabetes, Endocrinology and Metabolism Department of Internal Medicine Hyogo College of Medicine Nishinomiya Hyogo Japan
| | - Masayuki Miuchi
- Division of Diabetes, Endocrinology and Metabolism Department of Internal Medicine Hyogo College of Medicine Nishinomiya Hyogo Japan
| | - Takashi Ikawa
- Division of Diabetes, Endocrinology and Metabolism Department of Internal Medicine Hyogo College of Medicine Nishinomiya Hyogo Japan
| | - Takafumi Akagami
- Division of Diabetes, Endocrinology and Metabolism Department of Internal Medicine Hyogo College of Medicine Nishinomiya Hyogo Japan
| | - Masaru Tokuda
- Division of Diabetes, Endocrinology and Metabolism Department of Internal Medicine Hyogo College of Medicine Nishinomiya Hyogo Japan
| | - Tomoyuki Katsuno
- Division of Innovative Diabetes Treatment Hyogo College of Medicine Nishinomiya Hyogo Japan
| | | | | | - Mitsuyoshi Namba
- Division of Diabetes, Endocrinology and Metabolism Department of Internal Medicine Hyogo College of Medicine Nishinomiya Hyogo Japan
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Wellhauser L, Gojska NM, Belsham DD. Delineating the regulation of energy homeostasis using hypothalamic cell models. Front Neuroendocrinol 2015; 36:130-49. [PMID: 25223866 DOI: 10.1016/j.yfrne.2014.09.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 08/28/2014] [Accepted: 09/02/2014] [Indexed: 12/27/2022]
Abstract
Attesting to its intimate peripheral connections, hypothalamic neurons integrate nutritional and hormonal cues to effectively manage energy homeostasis according to the overall status of the system. Extensive progress in the identification of essential transcriptional and post-translational mechanisms regulating the controlled expression and actions of hypothalamic neuropeptides has been identified through the use of animal and cell models. This review will introduce the basic techniques of hypothalamic investigation both in vivo and in vitro and will briefly highlight the key advantages and challenges of their use. Further emphasis will be place on the use of immortalized models of hypothalamic neurons for in vitro study of feeding regulation, with a particular focus on cell lines proving themselves most fruitful in deciphering fundamental basics of NPY/AgRP, Proglucagon, and POMC neuropeptide function.
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Affiliation(s)
- Leigh Wellhauser
- Department of Physiology, University of Toronto, Toronto, Ontario M5G 1A8, Canada
| | - Nicole M Gojska
- Department of Physiology, University of Toronto, Toronto, Ontario M5G 1A8, Canada
| | - Denise D Belsham
- Departments of Physiology, Medicine and OB/GYN, University of Toronto, Toronto, Ontario M5G 1A8, Canada; Division of Cellular and Molecular Biology, Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario M5S 1A8, Canada.
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46
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Nakamura T, Yoshikawa T, Naganuma F, Mohsen A, Iida T, Miura Y, Sugawara A, Yanai K. Role of histamine H3 receptor in glucagon-secreting αTC1.6 cells. FEBS Open Bio 2014; 5:36-41. [PMID: 25685663 PMCID: PMC4309840 DOI: 10.1016/j.fob.2014.12.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Revised: 12/08/2014] [Accepted: 12/09/2014] [Indexed: 12/14/2022] Open
Abstract
Histamine H3 receptor is expressed in pancreatic α-cells. Histamine H3 receptor negatively regulates glucagon secretion from αTC1.6 cells. Immepip, a selective H3 receptor agonist, decreases serum glucagon concentration in rats.
Pancreatic α-cells secrete glucagon to maintain energy homeostasis. Although histamine has an important role in energy homeostasis, the expression and function of histamine receptors in pancreatic α-cells remains unknown. We found that the histamine H3 receptor (H3R) was expressed in mouse pancreatic α-cells and αTC1.6 cells, a mouse pancreatic α-cell line. H3R inhibited glucagon secretion from αTC1.6 cells by inhibiting an increase in intracellular Ca2+ concentration. We also found that immepip, a selective H3R agonist, decreased serum glucagon concentration in rats. These results suggest that H3R modulates glucagon secretion from pancreatic α-cells.
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Affiliation(s)
- Tadaho Nakamura
- Department of Pharmacology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8575, Japan
| | - Takeo Yoshikawa
- Department of Pharmacology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8575, Japan
| | - Fumito Naganuma
- Department of Pharmacology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8575, Japan
| | - Attayeb Mohsen
- Department of Pharmacology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8575, Japan
| | - Tomomitsu Iida
- Department of Pharmacology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8575, Japan
| | - Yamato Miura
- Department of Pharmacology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8575, Japan
| | - Akira Sugawara
- Department of Molecular Endocrinology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8575, Japan
| | - Kazuhiko Yanai
- Department of Pharmacology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8575, Japan
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O’Malley TJ, Fava GE, Zhang Y, Fonseca VA, Wu H. Progressive change of intra-islet GLP-1 production during diabetes development. Diabetes Metab Res Rev 2014; 30:661-8. [PMID: 24510483 PMCID: PMC4126896 DOI: 10.1002/dmrr.2534] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Revised: 01/19/2014] [Accepted: 02/01/2014] [Indexed: 12/28/2022]
Abstract
BACKGROUND Glucagon-like peptide 1 (GLP-1) and glucagon share the same precursor molecule proglucagon, but each arises from a distinct posttranslational process in a tissue-specific manner. Recently, it has been shown that GLP-1 is co-expressed with glucagon in pancreatic islet cells. This study was aimed to investigate the progressive changes of GLP-1 versus glucagon production in pancreatic islets during the course of diabetes development. METHODS Both type 1 (non-obese diabetes mice) and type 2 (db/db mice) diabetes models were employed in this study. The mice were monitored closely for their diabetes progression and were sacrificed at different stages according to their blood glucose levels. GLP-1 and glucagon expression in the pancreatic islets was examined using immunohistochemistry assays. Quantitative analysis was performed to evaluate the significance of the changes. RESULTS The ratio of GLP-1-expressing cells to glucagon-expressing cells in the islets showed significant, progressive increase with the development of diabetes in db/db mice. The increase of GLP-1 expression was in agreement with the upregulation of PC1/3 expression in these cells. Interestingly, intra-islet GLP-1 expression was not significantly changed during the development of type 1 diabetes in non-obese diabetes mice. CONCLUSIONS The study demonstrated that GLP-1 was progressively upregulated in pancreatic islets during type 2 diabetes development. In addition, the data suggest clear differences in intra-islet GLP-1 production between type 1 and type 2 diabetes developments. These differences may have an effect on the clinical and pathophysiological processes of these diseases and may be a target for therapeutic approaches.
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Affiliation(s)
| | | | | | | | - Hongju Wu
- Corresponding author: Dr. Hongju Wu, Department of Medicine, Tulane University, 1430 Tulane Ave.-SL53, New Orleans, LA 70112. Phone: 504-988-2153. Fax: 504-988-6271.
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48
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Blanco EH, Peinado JR, Martín MG, Lindberg I. Biochemical and cell biological properties of the human prohormone convertase 1/3 Ser357Gly mutation: a PC1/3 hypermorph. Endocrinology 2014; 155:3434-47. [PMID: 24932808 PMCID: PMC4138575 DOI: 10.1210/en.2013-2151] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Satiety and appetite signaling are accomplished by circulating peptide hormones. These peptide hormones require processing from larger precursors to become bioactive, often by the proprotein convertase 1/3 (PC1/3). Several subcellular maturation steps are necessary for PC1/3 to achieve its optimal enzymatic activity. Certain PC1/3 variants found in the general population slightly attenuate its enzymatic activity and are associated with obesity and diabetes. However, mutations that increase PC1/3 activity and/or affect its specificity could also have physiological consequences. We here present data showing that the known human Ser357Gly PC1/3 mutant (PC1/3(S357G)) represents a PC1/3 hypermorph. Conditioned media from human embryonic kidney-293 cells transfected with PC1/3(WT) and PC1/3(S357G) were collected and enzymatic activity characterized. PC1/3(S357G) exhibited a lower calcium dependence; a higher pH optimum (neutral); and a higher resistance to peptide inhibitors than the wild-type enzyme. PC1/3(S357G) exhibited increased cleavage to the C-terminally truncated form, and kinetic parameters of the full-length and truncated mutant enzymes were also altered. Lastly, the S357G mutation broadened the specificity of the enzyme; we detected PC2-like specificity on the substrate proCART, the precursor of the cocaine- and amphetamine regulated transcript neuropeptide known to be associated with obesity. The production of another anorexigenic peptide normally synthesized only by PC2, αMSH, was increased when proopiomelanocortin was coexpressed with PC1/3(S357G). Considering the aberrant enzymatic profile of PC1/3(S357G), we hypothesize that this enzyme possesses unusual processing activity that may significantly change the profile of circulating peptide hormones.
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Affiliation(s)
- Elias H Blanco
- Department of Anatomy and Neurobiology (E.H.B., J.R.P., I.L.), University of Maryland Medical School, Baltimore, Maryland 21201; and Department of Pediatrics (M.G.M.), Division of Gastroenterology and Nutrition, Mattel Children's Hospital and the David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095
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49
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Abstract
Oxyntomodulin (OXM) is a peptide hormone released from the gut in post-prandial state that activates both the glucagon-like peptide-1 receptor (GLP1R) and the glucagon receptor (GCGR) resulting in superior body weight lowering to selective GLP1R agonists. OXM reduces food intake and increases energy expenditure in humans. While activation of the GCGR increases glucose production posing a hyperglycemic risk, the simultaneous activation of the GLP1R counteracts this effect. Acute OXM infusion improves glucose tolerance in T2DM patients making dual agonists of the GCGR and GLP1R new promising treatments for diabetes and obesity with the potential for weight loss and glucose lowering superior to that of GLP1R agonists.
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Affiliation(s)
- Alessandro Pocai
- Janssen Research and Devolopment, Cardiovascular and Metabolic Disease, 1516 Welsh and McKean Roads, Spring House, PA 19477, USA
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50
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Guizzetti L, McGirr R, Dhanvantari S. Two dipolar α-helices within hormone-encoding regions of proglucagon are sorting signals to the regulated secretory pathway. J Biol Chem 2014; 289:14968-80. [PMID: 24727476 DOI: 10.1074/jbc.m114.563684] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Proglucagon is expressed in pancreatic α cells, intestinal L cells, and some hypothalamic and brainstem neurons. Tissue-specific processing of proglucagon yields three major peptide hormones as follows: glucagon in the α cells and glucagon-like peptides (GLP)-1 and -2 in the L cells and neurons. Efficient sorting and packaging into the secretory granules of the regulated secretory pathway in each cell type are required for nutrient-regulated secretion of these proglucagon-derived peptides. Our previous work suggested that proglucagon is directed into granules by intrinsic sorting signals after initial processing to glicentin and major proglucagon fragment (McGirr, R., Guizzetti, L., and Dhanvantari, S. (2013) J. Endocrinol. 217, 229-240), leading to the hypothesis that sorting signals may be present in multiple domains. In the present study, we show that the α-helices within glucagon and GLP-1, but not GLP-2, act as sorting signals by efficiently directing a heterologous secretory protein to the regulated secretory pathway. Biophysical characterization of these peptides revealed that glucagon and GLP-1 each encode a nonamphipathic, dipolar α-helix, whereas the helix in GLP-2 is not dipolar. Surprisingly, glicentin and major proglucagon fragment were sorted with different efficiencies, thus providing evidence that proglucagon is first sorted to granules prior to processing. In contrast to many other prohormones in which sorting is directed by ordered prodomains, the sorting determinants of proglucagon lie within the ordered hormone domains of glucagon and GLP-1, illustrating that each prohormone has its own sorting "signature."
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Affiliation(s)
| | - Rebecca McGirr
- the Metabolism/Diabetes and Imaging Programs, Lawson Health Research Institute, London, Ontario N6A 4V2, Canada
| | - Savita Dhanvantari
- From the Departments of Medical Biophysics, the Metabolism/Diabetes and Imaging Programs, Lawson Health Research Institute, London, Ontario N6A 4V2, Canada Pathology, and Medicine, University of Western Ontario, London, Ontario N6A 3K7 and
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