1
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Hill TG, Gao R, Benrick A, Kothegala L, Rorsman N, Santos C, Acreman S, Briant LJ, Dou H, Gandasi NR, Guida C, Haythorne E, Wallace M, Knudsen JG, Miranda C, Tolö J, Clark A, Davison L, Størling J, Tarasov A, Ashcroft FM, Rorsman P, Zhang Q. Loss of electrical β-cell to δ-cell coupling underlies impaired hypoglycaemia-induced glucagon secretion in type-1 diabetes. Nat Metab 2024:10.1038/s42255-024-01139-z. [PMID: 39313541 DOI: 10.1038/s42255-024-01139-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 08/30/2024] [Indexed: 09/25/2024]
Abstract
Diabetes mellitus involves both insufficient insulin secretion and dysregulation of glucagon secretion1. In healthy people, a fall in plasma glucose stimulates glucagon release and thereby increases counter-regulatory hepatic glucose production. This response is absent in many patients with type-1 diabetes (T1D)2, which predisposes to severe hypoglycaemia that may be fatal and accounts for up to 10% of the mortality in patients with T1D3. In rats with chemically induced or autoimmune diabetes, counter-regulatory glucagon secretion can be restored by SSTR antagonists4-7 but both the underlying cellular mechanism and whether it can be extended to humans remain unestablished. Here, we show that glucagon secretion is not stimulated by low glucose in isolated human islets from donors with T1D, a defect recapitulated in non-obese diabetic mice with T1D. This occurs because of hypersecretion of somatostatin, leading to aberrant paracrine inhibition of glucagon secretion. Normally, KATP channel-dependent hyperpolarization of β-cells at low glucose extends into the δ-cells through gap junctions, culminating in suppression of action potential firing and inhibition of somatostatin secretion. This 'electric brake' is lost following autoimmune destruction of the β-cells, resulting in impaired counter-regulation. This scenario accounts for the clinical observation that residual β-cell function correlates with reduced hypoglycaemia risk8.
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Affiliation(s)
- Thomas G Hill
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, UK
| | - Rui Gao
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, UK
| | - Anna Benrick
- Metabolic Research Unit, Institute of Neuroscience and Physiology, University of Göteborg, Göteborg, Sweden
| | - Lakshmi Kothegala
- Metabolic Research Unit, Institute of Neuroscience and Physiology, University of Göteborg, Göteborg, Sweden
- Department of Developmental Biology and Genetics (DBG), Indian Institute of Science (IISc), Bengaluru, India
| | - Nils Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, UK
| | - Cristiano Santos
- Metabolic Research Unit, Institute of Neuroscience and Physiology, University of Göteborg, Göteborg, Sweden
| | - Samuel Acreman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, UK
- Metabolic Research Unit, Institute of Neuroscience and Physiology, University of Göteborg, Göteborg, Sweden
| | - Linford J Briant
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, UK
| | - Haiqiang Dou
- Metabolic Research Unit, Institute of Neuroscience and Physiology, University of Göteborg, Göteborg, Sweden
| | - Nikhil R Gandasi
- Metabolic Research Unit, Institute of Neuroscience and Physiology, University of Göteborg, Göteborg, Sweden
- Department of Developmental Biology and Genetics (DBG), Indian Institute of Science (IISc), Bengaluru, India
| | - Claudia Guida
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, UK
| | - Elizabeth Haythorne
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Marsha Wallace
- Nuffield Department of Clinical Medicine, University of Oxford, Roosevelt Drive, Oxford, UK
- The Royal Veterinary College, Hatfield, Hertfordshire, UK
| | - Jakob G Knudsen
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, UK
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Caroline Miranda
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, UK
- Metabolic Research Unit, Institute of Neuroscience and Physiology, University of Göteborg, Göteborg, Sweden
| | - Johan Tolö
- Metabolic Research Unit, Institute of Neuroscience and Physiology, University of Göteborg, Göteborg, Sweden
| | - Anne Clark
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, UK
| | - Lucy Davison
- Nuffield Department of Clinical Medicine, University of Oxford, Roosevelt Drive, Oxford, UK
- The Royal Veterinary College, Hatfield, Hertfordshire, UK
| | - Joachim Størling
- Steno Diabetes Center Copenhagen, Translational Type 1 Diabetes Research, Herlev, Denmark
| | - Andrei Tarasov
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, UK
- Biomedical Sciences Research Institute, School of Biomedical Sciences, Ulster University, Coleraine, Northern Ireland, UK
| | - Frances M Ashcroft
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, UK.
- Metabolic Research Unit, Institute of Neuroscience and Physiology, University of Göteborg, Göteborg, Sweden.
- Biomedical Sciences Research Institute, School of Biomedical Sciences, Ulster University, Coleraine, Northern Ireland, UK.
- Oxford National Institute for Health Research, Biomedical Research Centre, Churchill Hospital, Oxford, UK.
| | - Quan Zhang
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, UK.
- Center for Neuroscience and Cell Biology (CNC), Centre for Innovative Biomedicine and Biotechnology (CIBB), University of Coimbra, Coimbra, Portugal.
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2
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Peart LA, Draper M, Tarasov AI. The impact of GLP-1 signalling on the energy metabolism of pancreatic islet β-cells and extrapancreatic tissues. Peptides 2024; 178:171243. [PMID: 38788902 DOI: 10.1016/j.peptides.2024.171243] [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: 03/27/2024] [Revised: 05/19/2024] [Accepted: 05/21/2024] [Indexed: 05/26/2024]
Abstract
Glucagon-like peptide-1 signalling impacts glucose homeostasis and appetite thereby indirectly affecting substrate availability at the whole-body level. The incretin canonically produces an insulinotropic effect, thereby lowering blood glucose levels by promoting the uptake and inhibiting the production of the sugar by peripheral tissues. Likewise, GLP-1 signalling within the central nervous system reduces the appetite and food intake, whereas its gastric effect delays the absorption of nutrients, thus improving glycaemic control and reducing the risk of postprandial hyperglycaemia. We review the molecular aspects of the GLP-1 signalling, focusing on its impact on intracellular energy metabolism. Whilst the incretin exerts its effects predominantly via a Gs receptor, which decodes the incretin signal into the elevation of intracellular cAMP levels, the downstream signalling cascades within the cell, acting on fast and slow timescales, resulting in an enhancement or an attenuation of glucose catabolism, respectively.
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Affiliation(s)
- Leah A Peart
- School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine, Northern Ireland BT52 1SA, UK
| | - Matthew Draper
- School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine, Northern Ireland BT52 1SA, UK
| | - Andrei I Tarasov
- School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine, Northern Ireland BT52 1SA, UK.
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3
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Kang Q, Jia J, Dean ED, Yuan H, Dai C, Li Z, Jiang F, Zhang XK, Powers AC, Chen W, Li M. ErbB3 is required for hyperaminoacidemia-induced pancreatic α cell hyperplasia. J Biol Chem 2024; 300:107499. [PMID: 38944125 PMCID: PMC11326907 DOI: 10.1016/j.jbc.2024.107499] [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: 03/14/2024] [Revised: 05/18/2024] [Accepted: 06/02/2024] [Indexed: 07/01/2024] Open
Abstract
Blood amino acid levels are maintained in a narrow physiological range. The pancreatic α cells have emerged as the primary aminoacidemia regulator through glucagon secretion to promote hepatic amino acid catabolism. Interruption of glucagon signaling disrupts the liver-α cells axis leading to hyperaminoacidemia, which triggers a compensatory rise in glucagon secretion and α cell hyperplasia. The mechanisms of hyperaminoacidemia-induced α cell hyperplasia remain incompletely understood. Using a mouse α cell line and in vivo studies in zebrafish and mice, we found that hyperaminoacidemia-induced α cell hyperplasia requires ErbB3 signaling. In addition to mechanistic target of rapamycin complex 1, another ErbB3 downstream effector signal transducer and activator of transcription 3 also plays a role in α cell hyperplasia. Mechanistically, ErbB3 may partner with ErbB2 to stimulate cyclin D2 and suppress p27 via mechanistic target of rapamycin complex 1 and signal transducer and activator of transcription 3. Our study identifies ErbB3 as a new regulator for hyperaminoacidemia-induced α cell proliferation and a critical component of the liver-α cells axis that regulates aminoacidemia.
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Affiliation(s)
- Qi Kang
- School of Pharmaceutical Sciences and School of Life Sciences, Xiamen University, Xiamen, China; Fujian Provincial Key Laboratory of Innovative Drug Target Research, School of Pharmaceutical Sciences, Xiamen University, Xiamen, China
| | - Jianxin Jia
- School of Pharmaceutical Sciences and School of Life Sciences, Xiamen University, Xiamen, China; Fujian Provincial Key Laboratory of Innovative Drug Target Research, School of Pharmaceutical Sciences, Xiamen University, Xiamen, China
| | - E Danielle Dean
- Departments of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA; Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Hang Yuan
- School of Pharmaceutical Sciences and School of Life Sciences, Xiamen University, Xiamen, China; Fujian Provincial Key Laboratory of Innovative Drug Target Research, School of Pharmaceutical Sciences, Xiamen University, Xiamen, China
| | - Chunhua Dai
- Departments of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA; Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Zhehui Li
- School of Pharmaceutical Sciences and School of Life Sciences, Xiamen University, Xiamen, China; Fujian Provincial Key Laboratory of Innovative Drug Target Research, School of Pharmaceutical Sciences, Xiamen University, Xiamen, China
| | - Fuquan Jiang
- School of Pharmaceutical Sciences and School of Life Sciences, Xiamen University, Xiamen, China; Fujian Provincial Key Laboratory of Innovative Drug Target Research, School of Pharmaceutical Sciences, Xiamen University, Xiamen, China
| | - Xiao-Kun Zhang
- School of Pharmaceutical Sciences and School of Life Sciences, Xiamen University, Xiamen, China; Fujian Provincial Key Laboratory of Innovative Drug Target Research, School of Pharmaceutical Sciences, Xiamen University, Xiamen, China
| | - Alvin C Powers
- Departments of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA; Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA; VA Tennessee Valley Healthcare System, Nashville, Tennessee, USA
| | - Wenbiao Chen
- Departments of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA.
| | - Mingyu Li
- School of Pharmaceutical Sciences and School of Life Sciences, Xiamen University, Xiamen, China; Fujian Provincial Key Laboratory of Innovative Drug Target Research, School of Pharmaceutical Sciences, Xiamen University, Xiamen, China; State Key Laboratory of Vaccines for Infectious Diseases, Xiang An Biomedicine Laboratory, Xiamen University, Xiamen, China.
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4
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Lewandowski SL, El K, Campbell JE. Evaluating glucose-dependent insulinotropic polypeptide and glucagon as key regulators of insulin secretion in the pancreatic islet. Am J Physiol Endocrinol Metab 2024; 327:E103-E110. [PMID: 38775725 PMCID: PMC11390117 DOI: 10.1152/ajpendo.00360.2023] [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: 11/01/2023] [Revised: 02/27/2024] [Accepted: 05/09/2024] [Indexed: 06/04/2024]
Abstract
The incretin axis is an essential component of postprandial insulin secretion and glucose homeostasis. There are two incretin hormones, glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), which exert multiple actions throughout the body. A key cellular target for the incretins are pancreatic β-cells, where they potentiate nutrient-stimulated insulin secretion. This feature of incretins has made this system an attractive target for therapeutic interventions aimed at controlling glycemia. Here, we discuss the role of GIP in both β-cells and α-cells within the islet, to stimulate insulin and glucagon secretion, respectively. Moreover, we discuss how glucagon secretion from α-cells has important insulinotropic actions in β-cells through an axis termed α- to β-cell communication. These recent advances have elevated the potential of GIP and glucagon as a therapeutic targets, coinciding with emerging compounds that pharmacologically leverage the actions of these two peptides in the context of diabetes and obesity.
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Affiliation(s)
- Sophie L Lewandowski
- Duke Molecular Physiology Institute, Duke University, Durham, North Carolina, United States
| | - Kimberley El
- Duke Molecular Physiology Institute, Duke University, Durham, North Carolina, United States
| | - Jonathan E Campbell
- Duke Molecular Physiology Institute, Duke University, Durham, North Carolina, United States
- Division of Endocrinology, Department of Medicine, Duke University, Durham, North Carolina, United States
- Department of Pharmacology and Cancer Biology, Duke University, Durham, North Carolina, United States
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5
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Han HW, Pradhan G, Villarreal D, Kim DM, Jain A, Gaharwar A, Tian Y, Guo S, Sun Y. GHSR Deletion in β-Cells of Male Mice: Ineffective in Obesity, but Effective in Protecting against Streptozotocin-Induced β-Cell Injury in Aging. Nutrients 2024; 16:1464. [PMID: 38794702 PMCID: PMC11123813 DOI: 10.3390/nu16101464] [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: 04/15/2024] [Revised: 05/09/2024] [Accepted: 05/10/2024] [Indexed: 05/26/2024] Open
Abstract
Insulin secretion from pancreatic β cells is a key pillar of glucose homeostasis, which is impaired under obesity and aging. Growth hormone secretagogue receptor (GHSR) is the receptor of nutrient-sensing hormone ghrelin. Previously, we showed that β-cell GHSR regulated glucose-stimulated insulin secretion (GSIS) in young mice. In the current study, we further investigated the effects of GHSR on insulin secretion in male mice under diet-induced obesity (DIO) and streptozotocin (STZ)-induced β-cell injury in aging. β-cell-specific-Ghsr-deficient (Ghsr-βKO) mice exhibited no glycemic phenotype under DIO but showed significantly improved ex vivo GSIS in aging. We also detected reduced insulin sensitivity and impaired insulin secretion during aging both in vivo and ex vivo. Accordingly, there were age-related alterations in expression of glucose transporter, insulin signaling pathway, and inflammatory genes. To further determine whether GHSR deficiency affected β-cell susceptibility to acute injury, young, middle-aged, and old Ghsr-βKO mice were subjected to STZ. We found that middle-aged and old Ghsr-βKO mice were protected from STZ-induced hyperglycemia and impaired insulin secretion, correlated with increased expression of insulin signaling regulators but decreased pro-inflammatory cytokines in pancreatic islets. Collectively, our findings indicate that β-cell GHSR has a major impact on insulin secretion in aging but not obesity, and GHSR deficiency protects against STZ-induced β-cell injury in aging.
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Affiliation(s)
- Hye Won Han
- Department of Nutrition, Texas A&M University, College Station, TX 77843, USA; (H.W.H.)
| | - Geetali Pradhan
- USDA/ARS Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
- Interdepartmental Program in Translational Biology and Molecular Medicine, Baylor College of Medicine, Houston, TX 77030, USA
| | - Daniel Villarreal
- Department of Nutrition, Texas A&M University, College Station, TX 77843, USA; (H.W.H.)
| | - Da Mi Kim
- Department of Nutrition, Texas A&M University, College Station, TX 77843, USA; (H.W.H.)
| | - Abhishek Jain
- Department of Biomedical Engineering, College of Engineering, Texas A&M University, College Station, TX 77843, USA
| | - Akhilesh Gaharwar
- Department of Biomedical Engineering, College of Engineering, Texas A&M University, College Station, TX 77843, USA
| | - Yanan Tian
- Department of Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
| | - Shaodong Guo
- Department of Nutrition, Texas A&M University, College Station, TX 77843, USA; (H.W.H.)
| | - Yuxiang Sun
- Department of Nutrition, Texas A&M University, College Station, TX 77843, USA; (H.W.H.)
- USDA/ARS Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
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6
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Shilleh AH, Viloria K, Broichhagen J, Campbell JE, Hodson DJ. GLP1R and GIPR expression and signaling in pancreatic alpha cells, beta cells and delta cells. Peptides 2024; 175:171179. [PMID: 38360354 DOI: 10.1016/j.peptides.2024.171179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Revised: 02/09/2024] [Accepted: 02/13/2024] [Indexed: 02/17/2024]
Abstract
Glucagon-like peptide-1 receptor (GLP1R) and glucose-dependent insulinotropic polypeptide receptor (GIPR) are transmembrane receptors involved in insulin, glucagon and somatostatin secretion from the pancreatic islet. Therapeutic targeting of GLP1R and GIPR restores blood glucose levels in part by influencing beta cell, alpha cell and delta cell function. Despite the importance of the incretin-mimetics for diabetes therapy, our understanding of GLP1R and GIPR expression patterns and signaling within the islet remain incomplete. Here, we present the evidence for GLP1R and GIPR expression in the major islet cell types, before addressing signaling pathway(s) engaged, as well as their influence on cell survival and function. While GLP1R is largely a beta cell-specific marker within the islet, GIPR is expressed in alpha cells, beta cells, and (possibly) delta cells. GLP1R and GIPR engage Gs-coupled pathways in most settings, although the exact outcome on hormone release depends on paracrine communication and promiscuous signaling. Biased agonism away from beta-arrestin is an emerging concept for improving therapeutic efficacy, and is also relevant for GLP1R/GIPR dual agonism. Lastly, dual agonists exert multiple effects on islet function through GIPR > GLP1R imbalance, increased GLP1R surface expression and cAMP signaling, as well as beneficial alpha cell-beta cell-delta cell crosstalk.
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Affiliation(s)
- Ali H Shilleh
- Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), NIHR Oxford Biomedical Research Centre, Churchill Hospital, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Katrina Viloria
- Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), NIHR Oxford Biomedical Research Centre, Churchill Hospital, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | | | - Jonathan E Campbell
- Duke Molecular Physiology Institute, USA; Department of Medicine, Division of Endocrinology, Duke University, Durham, NC, USA; Department of Pharmacology and Cancer Biology, Duke University, Durham, NC, USA.
| | - David J Hodson
- Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), NIHR Oxford Biomedical Research Centre, Churchill Hospital, Radcliffe Department of Medicine, University of Oxford, Oxford, UK.
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7
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Gupta D, Burstein AW, Shankar K, Varshney S, Singh O, Osborne-Lawrence S, Richard CP, Zigman JM. Impact of Ghrelin on Islet Size in Nonpregnant and Pregnant Female Mice. Endocrinology 2024; 165:bqae048. [PMID: 38626085 PMCID: PMC11075791 DOI: 10.1210/endocr/bqae048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Revised: 04/03/2024] [Accepted: 04/12/2024] [Indexed: 04/18/2024]
Abstract
Reducing ghrelin by ghrelin gene knockout (GKO), ghrelin-cell ablation, or high-fat diet feeding increases islet size and β-cell mass in male mice. Here we determined if reducing ghrelin also enlarges islets in females and if pregnancy-associated changes in islet size are related to reduced ghrelin. Islet size and β-cell mass were larger (P = .057 for β-cell mass) in female GKO mice. Pregnancy was associated with reduced ghrelin and increased liver-expressed antimicrobial peptide-2 (LEAP2; a ghrelin receptor antagonist) in wild-type mice. Ghrelin deletion and pregnancy each increased islet size (by ∼19.9-30.2% and ∼34.9-46.4%, respectively), percentage of large islets (>25 µm2×103, by ∼21.8-42% and ∼21.2-41.2%, respectively), and β-cell mass (by ∼15.7-23.8% and ∼65.2-76.8%, respectively). Neither islet cross-sectional area, β-cell cross-sectional area, nor β-cell mass correlated with plasma ghrelin, although all positively correlated with LEAP2 (P = .081 for islet cross-sectional area). In ad lib-fed mice, there was an effect of pregnancy, but not ghrelin deletion, to change (raise) plasma insulin without impacting blood glucose. Similarly, there was an effect of pregnancy, but not ghrelin deletion, to change (lower) blood glucose area under the curve during a glucose tolerance test. Thus, genetic deletion of ghrelin increases islet size and β-cell cross-sectional area in female mice, similar to males. Yet, despite pregnancy-associated reductions in ghrelin, other factors appear to govern islet enlargement and changes to insulin sensitivity and glucose tolerance in the setting of pregnancy. In the case of islet size and β-cell mass, one of those factors may be the pregnancy-associated increase in LEAP2.
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Affiliation(s)
- Deepali Gupta
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Avi W Burstein
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Kripa Shankar
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Salil Varshney
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Omprakash Singh
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Sherri Osborne-Lawrence
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Corine P Richard
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jeffrey M Zigman
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX 75390, USA
- Division of Endocrinology & Metabolism, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX 75390, USA
- Department of Psychiatry, UT Southwestern Medical Center, Dallas, TX 75390, USA
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8
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Hill TG, Hill DJ. The Importance of Intra-Islet Communication in the Function and Plasticity of the Islets of Langerhans during Health and Diabetes. Int J Mol Sci 2024; 25:4070. [PMID: 38612880 PMCID: PMC11012451 DOI: 10.3390/ijms25074070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Revised: 03/27/2024] [Accepted: 03/27/2024] [Indexed: 04/14/2024] Open
Abstract
Islets of Langerhans are anatomically dispersed within the pancreas and exhibit regulatory coordination between islets in response to nutritional and inflammatory stimuli. However, within individual islets, there is also multi-faceted coordination of function between individual beta-cells, and between beta-cells and other endocrine and vascular cell types. This is mediated partly through circulatory feedback of the major secreted hormones, insulin and glucagon, but also by autocrine and paracrine actions within the islet by a range of other secreted products, including somatostatin, urocortin 3, serotonin, glucagon-like peptide-1, acetylcholine, and ghrelin. Their availability can be modulated within the islet by pericyte-mediated regulation of microvascular blood flow. Within the islet, both endocrine progenitor cells and the ability of endocrine cells to trans-differentiate between phenotypes can alter endocrine cell mass to adapt to changed metabolic circumstances, regulated by the within-islet trophic environment. Optimal islet function is precariously balanced due to the high metabolic rate required by beta-cells to synthesize and secrete insulin, and they are susceptible to oxidative and endoplasmic reticular stress in the face of high metabolic demand. Resulting changes in paracrine dynamics within the islets can contribute to the emergence of Types 1, 2 and gestational diabetes.
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Affiliation(s)
- Thomas G. Hill
- Oxford Centre for Diabetes, Endocrinology, and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DU, UK
| | - David J. Hill
- Lawson Health Research Institute, St. Joseph’s Health Care, London, ON N6A 4V2, Canada;
- Departments of Medicine, Physiology and Pharmacology, Western University, London, ON N6A 3K7, Canada
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9
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Turbitt J, Moffett RC, Brennan L, Johnson PRV, Flatt PR, McClenaghan NH, Tarasov AI. Molecular determinants and intracellular targets of taurine signalling in pancreatic islet β-cells. Acta Physiol (Oxf) 2024; 240:e14101. [PMID: 38243723 DOI: 10.1111/apha.14101] [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: 06/26/2023] [Revised: 12/26/2023] [Accepted: 01/08/2024] [Indexed: 01/21/2024]
Abstract
AIM Despite its abundance in pancreatic islets of Langerhans and proven antihyperglycemic effects, the impact of the essential amino acid, taurine, on islet β-cell biology has not yet received due consideration, which prompted the current studies exploring the molecular selectivity of taurine import into β-cells and its acute and chronic intracellular interactions. METHODS The molecular aspects of taurine transport were probed by exposing the clonal pancreatic BRIN BD11 β-cells and primary mouse and human islets to a range of the homologs of the amino acid (assayed at 2-20 mM), using the hormone release and imaging of intracellular signals as surrogate read-outs. Known secretagogues were employed to profile the interaction of taurine with acute and chronic intracellular signals. RESULTS Taurine transporter TauT was expressed in the islet β-cells, with the transport of taurine and homologs having a weak sulfonate specificity but significant sensitivity to the molecular weight of the transporter. Taurine, hypotaurine, homotaurine, and β-alanine enhanced insulin secretion in a glucose-dependent manner, an action potentiated by cytosolic Ca2+ and cAMP. Acute and chronic β-cell insulinotropic effects of taurine were highly sensitive to co-agonism with GLP-1, forskolin, tolbutamide, and membrane depolarization, with an unanticipated indifference to the activation of PKC and CCK8 receptors. Pre-culturing with GLP-1 or KATP channel inhibitors sensitized or, respectively, desensitized β-cells to the acute taurine stimulus. CONCLUSION Together, these data demonstrate the pathways whereby taurine exhibits a range of beneficial effects on insulin secretion and β-cell function, consistent with the antidiabetic potential of its dietary low-dose supplementation.
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Affiliation(s)
- Julie Turbitt
- School of Biomedical Sciences, Ulster University, Coleraine, UK
| | | | - Lorraine Brennan
- UCD Institute of Food and Health, UCD School of Agriculture and Food Science, University College Dublin, Dublin 4, Republic of Ireland
- UCD Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin 4, Republic of Ireland
| | - Paul R V Johnson
- Nuffield Department of Surgical Sciences, Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK
- Oxford Biomedical Research Centre (OxBRC), Oxford, UK
| | - Peter R Flatt
- School of Biomedical Sciences, Ulster University, Coleraine, UK
| | - Neville H McClenaghan
- School of Biomedical Sciences, Ulster University, Coleraine, UK
- Department of Life Sciences, Atlantic Technological University, Sligo, Republic of Ireland
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10
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Röthe J, Kraft R, Ricken A, Kaczmarek I, Matz-Soja M, Winter K, Dietzsch AN, Buchold J, Ludwig MG, Liebscher I, Schöneberg T, Thor D. The adhesion GPCR GPR116/ADGRF5 has a dual function in pancreatic islets regulating somatostatin release and islet development. Commun Biol 2024; 7:104. [PMID: 38228886 PMCID: PMC10791652 DOI: 10.1038/s42003-024-05783-9] [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: 11/03/2023] [Accepted: 01/05/2024] [Indexed: 01/18/2024] Open
Abstract
Glucose homeostasis is maintained by hormones secreted from different cell types of the pancreatic islets and controlled by manifold input including signals mediated through G protein-coupled receptors (GPCRs). RNA-seq analyses revealed expression of numerous GPCRs in mouse and human pancreatic islets, among them Gpr116/Adgrf5. GPR116 is an adhesion GPCR mainly found in lung and required for surfactant secretion. Here, we demonstrate that GPR116 is involved in the somatostatin release from pancreatic delta cells using a whole-body as well as a cell-specific knock-out mouse model. Interestingly, the whole-body GPR116 deficiency causes further changes such as decreased beta-cell mass, lower number of small islets, and reduced pancreatic insulin content. Glucose homeostasis in global GPR116-deficient mice is maintained by counter-acting mechanisms modulating insulin degradation. Our data highlight an important function of GPR116 in controlling glucose homeostasis.
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Affiliation(s)
- Juliane Röthe
- Rudolf Schönheimer Institute of Biochemistry, Medical Faculty, Leipzig University, Leipzig, Germany
| | - Robert Kraft
- Carl-Ludwig-Institute for Physiology, Medical Faculty, Leipzig University, Leipzig, Germany
| | - Albert Ricken
- Institute of Anatomy, Medical Faculty, Leipzig University, Leipzig, Germany
| | - Isabell Kaczmarek
- Rudolf Schönheimer Institute of Biochemistry, Medical Faculty, Leipzig University, Leipzig, Germany
| | - Madlen Matz-Soja
- Medical Department II - Gastroenterology, Hepatology, Infectious Diseases, Pneumology, University Medical Center, Leipzig, Germany
- Division of Hepatology, Clinic and Polyclinic for Oncology, Gastroenterology, Hepatology, Infectious Diseases, and Pneumology, University Hospital, Leipzig, Germany
| | - Karsten Winter
- Institute of Anatomy, Medical Faculty, Leipzig University, Leipzig, Germany
| | - André Nguyen Dietzsch
- Rudolf Schönheimer Institute of Biochemistry, Medical Faculty, Leipzig University, Leipzig, Germany
| | - Julia Buchold
- Rudolf Schönheimer Institute of Biochemistry, Medical Faculty, Leipzig University, Leipzig, Germany
| | | | - Ines Liebscher
- Rudolf Schönheimer Institute of Biochemistry, Medical Faculty, Leipzig University, Leipzig, Germany
| | - Torsten Schöneberg
- Rudolf Schönheimer Institute of Biochemistry, Medical Faculty, Leipzig University, Leipzig, Germany
| | - Doreen Thor
- Rudolf Schönheimer Institute of Biochemistry, Medical Faculty, Leipzig University, Leipzig, Germany.
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11
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Gupta D, Burstein AW, Schwalbe DC, Shankar K, Varshney S, Singh O, Paul S, Ogden SB, Osborne-Lawrence S, Metzger NP, Richard CP, Campbell JN, Zigman JM. Ghrelin deletion and conditional ghrelin cell ablation increase pancreatic islet size in mice. J Clin Invest 2023; 133:e169349. [PMID: 38099492 PMCID: PMC10721155 DOI: 10.1172/jci169349] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 10/05/2023] [Indexed: 12/18/2023] Open
Abstract
Ghrelin exerts key effects on islet hormone secretion to regulate blood glucose levels. Here, we sought to determine whether ghrelin's effects on islets extend to the alteration of islet size and β cell mass. We demonstrate that reducing ghrelin - by ghrelin gene knockout (GKO), conditional ghrelin cell ablation, or high-fat diet (HFD) feeding - was associated with increased mean islet size (up to 62%), percentage of large islets (up to 854%), and β cell cross-sectional area (up to 51%). In GKO mice, these effects were more apparent in 10- to 12-week-old mice than in 4-week-old mice. Higher β cell numbers from decreased β cell apoptosis drove the increase in β cell cross-sectional area. Conditional ghrelin cell ablation in adult mice increased the β cell number per islet by 40% within 4 weeks. A negative correlation between islet size and plasma ghrelin in HFD-fed plus chow-fed WT mice, together with even larger islet sizes in HFD-fed GKO mice than in HFD-fed WT mice, suggests that reduced ghrelin was not solely responsible for diet-induced obesity-associated islet enlargement. Single-cell transcriptomics revealed changes in gene expression in several GKO islet cell types, including upregulation of Manf, Dnajc3, and Gnas expression in β cells, which supports decreased β cell apoptosis and/or increased β cell proliferation. These effects of ghrelin reduction on islet morphology might prove useful when designing new therapies for diabetes.
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Affiliation(s)
- Deepali Gupta
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Avi W. Burstein
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Dana C. Schwalbe
- Department of Biology, University of Virginia, Charlottesville, Virginia, USA
| | - Kripa Shankar
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Salil Varshney
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Omprakash Singh
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Subhojit Paul
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Sean B. Ogden
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Sherri Osborne-Lawrence
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Nathan P. Metzger
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Corine P. Richard
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - John N. Campbell
- Department of Biology, University of Virginia, Charlottesville, Virginia, USA
| | - Jeffrey M. Zigman
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
- Division of Endocrinology and Metabolism, Department of Internal Medicine and
- Department of Psychiatry, UT Southwestern Medical Center, Dallas, Texas, USA
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12
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Bany Bakar R, Reimann F, Gribble FM. The intestine as an endocrine organ and the role of gut hormones in metabolic regulation. Nat Rev Gastroenterol Hepatol 2023; 20:784-796. [PMID: 37626258 DOI: 10.1038/s41575-023-00830-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/25/2023] [Indexed: 08/27/2023]
Abstract
Gut hormones orchestrate pivotal physiological processes in multiple metabolically active tissues, including the pancreas, liver, adipose tissue, gut and central nervous system, making them attractive therapeutic targets in the treatment of obesity and type 2 diabetes mellitus. Most gut hormones are derived from enteroendocrine cells, but bioactive peptides that are derived from other intestinal epithelial cell types have also been implicated in metabolic regulation and can be considered gut hormones. A deeper understanding of the complex inter-organ crosstalk mediated by the intestinal endocrine system is a prerequisite for designing more effective drugs that are based on or target gut hormones and their receptors, and extending their therapeutic potential beyond obesity and diabetes mellitus. In this Review, we present an overview of gut hormones that are involved in the regulation of metabolism and discuss their action in the gastrointestinal system and beyond.
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Affiliation(s)
- Rula Bany Bakar
- Wellcome Trust-MRC Institute of Metabolic Science Metabolic Research Laboratories, University of Cambridge, Cambridge, UK
| | - Frank Reimann
- Wellcome Trust-MRC Institute of Metabolic Science Metabolic Research Laboratories, University of Cambridge, Cambridge, UK
| | - Fiona M Gribble
- Wellcome Trust-MRC Institute of Metabolic Science Metabolic Research Laboratories, University of Cambridge, Cambridge, UK.
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13
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Zaïmia N, Obeid J, Varrault A, Sabatier J, Broca C, Gilon P, Costes S, Bertrand G, Ravier MA. GLP-1 and GIP receptors signal through distinct β-arrestin 2-dependent pathways to regulate pancreatic β cell function. Cell Rep 2023; 42:113326. [PMID: 37897727 DOI: 10.1016/j.celrep.2023.113326] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 09/14/2023] [Accepted: 10/07/2023] [Indexed: 10/30/2023] Open
Abstract
Glucagon-like peptide 1 (GLP-1R) and glucose-dependent insulinotropic polypeptide (GIPR) receptors are G-protein-coupled receptors involved in glucose homeostasis. Diabetogenic conditions decrease β-arrestin 2 (ARRB2) levels in human islets. In mouse β cells, ARRB2 dampens insulin secretion by partially uncoupling cyclic AMP (cAMP)/protein kinase A (PKA) signaling at physiological doses of GLP-1, whereas at pharmacological doses, the activation of extracellular signal-related kinase (ERK)/cAMP-responsive element-binding protein (CREB) requires ARRB2. In contrast, GIP-potentiated insulin secretion needs ARRB2 in mouse and human islets. The GIPR-ARRB2 axis is not involved in cAMP/PKA or ERK signaling but does mediate GIP-induced F-actin depolymerization. Finally, the dual GLP-1/GIP agonist tirzepatide does not require ARRB2 for the potentiation of insulin secretion. Thus, ARRB2 plays distinct roles in regulating GLP-1R and GIPR signaling, and we highlight (1) its role in the physiological context and the possible functional consequences of its decreased expression in pathological situations such as diabetes and (2) the importance of assessing the signaling pathways engaged by the agonists (biased/dual) for therapeutic purposes.
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Affiliation(s)
- Nour Zaïmia
- IGF, Université Montpellier, CNRS, INSERM, Montpellier, France
| | - Joelle Obeid
- IGF, Université Montpellier, CNRS, INSERM, Montpellier, France
| | - Annie Varrault
- IGF, Université Montpellier, CNRS, INSERM, Montpellier, France
| | | | | | - Patrick Gilon
- Université Catholique de Louvain, Institut de Recherche Expérimental et Clinique, Pôle d'Endocrinologie, Diabète, et Nutrition, Brussels, Belgium
| | - Safia Costes
- IGF, Université Montpellier, CNRS, INSERM, Montpellier, France
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14
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Byberg S, Blond MB, Holm S, Amadid H, Nielsen LB, Clemmensen KKB, Færch K, Holst B. LEAP2 is associated with cardiometabolic markers but is unchanged by antidiabetic treatment in people with prediabetes. Am J Physiol Endocrinol Metab 2023; 325:E244-E251. [PMID: 37436962 DOI: 10.1152/ajpendo.00023.2023] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 07/05/2023] [Accepted: 07/06/2023] [Indexed: 07/14/2023]
Abstract
To examine whether fasting plasma liver-expressed antimicrobial peptide 2 (FP-LEAP2) is associated with markers of cardiometabolic disease susceptibility in a cohort with prediabetes and overweight/obesity and whether antidiabetic interventions affect FP-LEAP2 levels. The analysis included 115 individuals with prediabetes [hemoglobin A1c (HbA1c) 39-47 mmol/mol, 5.7%-6.4%] and overweight/obesity [body mass index (BMI) ≥ 25 kg/m2] from a randomized controlled trial. Changes in FP-LEAP2 levels were assessed in relation to treatment with dapagliflozin (10 mg once daily), metformin (1,700 mg daily), or interval-based exercise (5 days/wk, 30 min/session) compared with control (habitual lifestyle) after 6 and 13 wk of treatment. FP-LEAP2 levels were positively associated with [standardized beta coefficient (95% CI)]: BMI 0.22 (0.03:0.41), P = 0.027; body weight 0.27 (0.06:0.48), P = 0.013; fat mass 0.2 (0.00:0.4), P = 0.048; lean mass 0.47 (0.13:0.8), P = 0.008; HbA1c 0.35 (0.17:0.53), P < 0.001; fasting plasma glucose (FPG) 0.32 (0.12:0.51), P = 0.001; fasting serum insulin 0.28 (0.09:0.47), P = 0.005; total cholesterol 0.19 (0.01:0.38), P = 0.043; triglycerides 0.31 (0.13:0.5), P < 0.001; and transaminases and fatty liver index (standardized beta coefficients 0.23-0.32), all P < 0.020. FP-LEAP2 levels were inversely associated with insulin sensitivity [-0.22 (-0.41: -0.03), P = 0.022] and kidney function [estimated glomerular filtration rate (eGFR) -0.34 (-0.56: -0.12), P = 0.003]. FP-LEAP2 levels were not associated with fat distribution or body fat percentage, fasting glucagon, postload glucose, β-cell function, or low-density lipoprotein. The interventions were not associated with changes in FP-LEAP2. FP-LEAP2 is associated with body mass, impaired insulin sensitivity, liver-specific enzymes, and kidney function. The findings highlight the importance of studying LEAP2 in obesity, type 2 diabetes, and nonalcoholic fatty liver disease. FP-LEAP2 was not affected by metformin, dapaglifloxin, or exercise in this population.NEW & NOTEWORTHY LEAP2, primarily secreted by the liver, increases with greater body mass, insulin resistance, and liver-specific enzymes in individuals with prediabetes and overweight or obesity. Fasting glucose, body mass, and alanine aminotransferase independently predict LEAP2 levels. LEAP2 is inversely linked to impaired kidney function. Elevated LEAP2 levels might indicate an increased metabolic risk, warranting further investigation into its potential involvement in glucose and body weight control.
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Affiliation(s)
- Sarah Byberg
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Martin Bæk Blond
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Department of Clinical Research, Copenhagen University Hospital - Steno Diabetes Center Copenhagen, Herlev, Denmark
| | - Stephanie Holm
- 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
| | - Hanan Amadid
- Department of Data Science, Novo Nordisk, Herlev, Denmark
| | | | | | - Kristine Færch
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Department of Clinical Research, Copenhagen University Hospital - Steno Diabetes Center Copenhagen, Herlev, Denmark
| | - Birgitte Holst
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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15
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Wewer Albrechtsen NJ, Holst JJ, Cherrington AD, Finan B, Gluud LL, Dean ED, Campbell JE, Bloom SR, Tan TMM, Knop FK, Müller TD. 100 years of glucagon and 100 more. Diabetologia 2023; 66:1378-1394. [PMID: 37367959 DOI: 10.1007/s00125-023-05947-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Accepted: 04/18/2023] [Indexed: 06/28/2023]
Abstract
The peptide hormone glucagon, discovered in late 1922, is secreted from pancreatic alpha cells and is an essential regulator of metabolic homeostasis. This review summarises experiences since the discovery of glucagon regarding basic and clinical aspects of this hormone and speculations on the future directions for glucagon biology and glucagon-based therapies. The review was based on the international glucagon conference, entitled 'A hundred years with glucagon and a hundred more', held in Copenhagen, Denmark, in November 2022. The scientific and therapeutic focus of glucagon biology has mainly been related to its role in diabetes. In type 1 diabetes, the glucose-raising properties of glucagon have been leveraged to therapeutically restore hypoglycaemia. The hyperglucagonaemia evident in type 2 diabetes has been proposed to contribute to hyperglycaemia, raising questions regarding underlying mechanism and the importance of this in the pathogenesis of diabetes. Mimicry experiments of glucagon signalling have fuelled the development of several pharmacological compounds including glucagon receptor (GCGR) antagonists, GCGR agonists and, more recently, dual and triple receptor agonists combining glucagon and incretin hormone receptor agonism. From these studies and from earlier observations in extreme cases of either glucagon deficiency or excess secretion, the physiological role of glucagon has expanded to also involve hepatic protein and lipid metabolism. The interplay between the pancreas and the liver, known as the liver-alpha cell axis, reflects the importance of glucagon for glucose, amino acid and lipid metabolism. In individuals with diabetes and fatty liver diseases, glucagon's hepatic actions may be partly impaired resulting in elevated levels of glucagonotropic amino acids, dyslipidaemia and hyperglucagonaemia, reflecting a new, so far largely unexplored pathophysiological phenomenon termed 'glucagon resistance'. Importantly, the hyperglucagonaemia as part of glucagon resistance may result in increased hepatic glucose production and hyperglycaemia. Emerging glucagon-based therapies show a beneficial impact on weight loss and fatty liver diseases and this has sparked a renewed interest in glucagon biology to enable further pharmacological pursuits.
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Affiliation(s)
- Nicolai J Wewer Albrechtsen
- Department of Clinical Biochemistry, Copenhagen University Hospital - Bispebjerg and Frederiksberg Hospital, Copenhagen, Denmark.
- Novo Nordisk Foundation Center for Protein 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
| | - Alan D Cherrington
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Brian Finan
- Novo Nordisk Research Center Indianapolis, Indianapolis, IN, USA
| | - Lise Lotte Gluud
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Gastro Unit, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark
| | - E Danielle Dean
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Jonathan E Campbell
- Duke Molecular Physiology Institute, Duke University Medical Center, Durham, NC, USA
- Department of Medicine, Endocrinology Division, Duke University Medical Center, Durham, NC, USA
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC, USA
| | - Stephen R Bloom
- Department of Metabolism, Digestion and Reproduction, Imperial College London, London, UK
| | - Tricia M-M Tan
- Department of Metabolism, Digestion and Reproduction, Imperial College London, London, UK
| | - Filip K Knop
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Center for Clinical Metabolic Research, Gentofte Hospital, University of Copenhagen, Hellerup, Denmark
- Steno Diabetes Center Copenhagen, Herlev, Denmark
| | - Timo D Müller
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Center Munich, Neuherberg, Germany
- German Center for Diabetes Research (DZD), München Neuherberg, Germany
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16
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Shankar K, Varshney S, Gupta D, Mani BK, Osborne-Lawrence S, Metzger NP, Richard CP, Zigman JM. Ghrelin does not impact the blunted counterregulatory response to recurrent hypoglycemia in mice. Front Endocrinol (Lausanne) 2023; 14:1181856. [PMID: 37334290 PMCID: PMC10272800 DOI: 10.3389/fendo.2023.1181856] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 05/23/2023] [Indexed: 06/20/2023] Open
Abstract
Introduction Recurrent episodes of insulin-induced hypoglycemia in patients with diabetes mellitus can result in hypoglycemia-associated autonomic failure (HAAF), which is characterized by a compromised response to hypoglycemia by counterregulatory hormones (counterregulatory response; CRR) and hypoglycemia unawareness. HAAF is a leading cause of morbidity in diabetes and often hinders optimal regulation of blood glucose levels. Yet, the molecular pathways underlying HAAF remain incompletely described. We previously reported that in mice, ghrelin is permissive for the usual CRR to insulin-induced hypoglycemia. Here, we tested the hypothesis that attenuated release of ghrelin both results from HAAF and contributes to HAAF. Methods C57BL/6N mice, ghrelin-knockout (KO) + control mice, and GhIRKO (ghrelin cell-selective insulin receptor knockout) + control mice were randomized to one of three treatment groups: a "Euglycemia" group was injected with saline and remained euglycemic; a 1X hypoglycemia ("1X Hypo") group underwent a single episode of insulin-induced hypoglycemia; a recurrent hypoglycemia ("Recurrent Hypo") group underwent repeated episodes of insulin-induced hypoglycemia over five successive days. Results Recurrent hypoglycemia exaggerated the reduction in blood glucose (by ~30%) and attenuated the elevations in plasma levels of the CRR hormones glucagon (by 64.5%) and epinephrine (by 52.9%) in C57BL/6N mice compared to a single hypoglycemic episode. Yet, plasma ghrelin was equivalently reduced in "1X Hypo" and "Recurrent Hypo" C57BL/6N mice. Ghrelin-KO mice exhibited neither exaggerated hypoglycemia in response to recurrent hypoglycemia, nor any additional attenuation in CRR hormone levels compared to wild-type littermates. Also, in response to recurrent hypoglycemia, GhIRKO mice exhibited nearly identical blood glucose and plasma CRR hormone levels as littermates with intact insulin receptor expression (floxed-IR mice), despite higher plasma ghrelin in GhIRKO mice. Conclusions These data suggest that the usual reduction of plasma ghrelin due to insulin-induced hypoglycemia is unaltered by recurrent hypoglycemia and that ghrelin does not impact blood glucose or the blunted CRR hormone responses during recurrent hypoglycemia.
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Affiliation(s)
- Kripa Shankar
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Salil Varshney
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Deepali Gupta
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Bharath K. Mani
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Sherri Osborne-Lawrence
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Nathan P. Metzger
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Corine P. Richard
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Jeffrey M. Zigman
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, United States
- Division of Endocrinology, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, United States
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, United States
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17
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Mu-U-Min RBA, Diane A, Allouch A, Al-Siddiqi HH. Ca 2+-Mediated Signaling Pathways: A Promising Target for the Successful Generation of Mature and Functional Stem Cell-Derived Pancreatic Beta Cells In Vitro. Biomedicines 2023; 11:1577. [PMID: 37371672 DOI: 10.3390/biomedicines11061577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 05/18/2023] [Accepted: 05/23/2023] [Indexed: 06/29/2023] Open
Abstract
Diabetes mellitus is a chronic disease affecting over 500 million adults globally and is mainly categorized as type 1 diabetes mellitus (T1DM), where pancreatic beta cells are destroyed, and type 2 diabetes mellitus (T2DM), characterized by beta cell dysfunction. This review highlights the importance of the divalent cation calcium (Ca2+) and its associated signaling pathways in the proper functioning of beta cells and underlines the effects of Ca2+ dysfunction on beta cell function and its implications for the onset of diabetes. Great interest and promise are held by human pluripotent stem cell (hPSC) technology to generate functional pancreatic beta cells from diabetic patient-derived stem cells to replace the dysfunctional cells, thereby compensating for insulin deficiency and reducing the comorbidities of the disease and its associated financial and social burden on the patient and society. Beta-like cells generated by most current differentiation protocols have blunted functionality compared to their adult human counterparts. The Ca2+ dynamics in stem cell-derived beta-like cells and adult beta cells are summarized in this review, revealing the importance of proper Ca2+ homeostasis in beta-cell function. Consequently, the importance of targeting Ca2+ function in differentiation protocols is suggested to improve current strategies to use hPSCs to generate mature and functional beta-like cells with a comparable glucose-stimulated insulin secretion (GSIS) profile to adult beta cells.
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Affiliation(s)
- Razik Bin Abdul Mu-U-Min
- Diabetes Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation (QF), Doha P.O. Box 34110, Qatar
| | - Abdoulaye Diane
- Diabetes Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation (QF), Doha P.O. Box 34110, Qatar
| | - Asma Allouch
- Diabetes Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation (QF), Doha P.O. Box 34110, Qatar
| | - Heba H Al-Siddiqi
- Diabetes Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation (QF), Doha P.O. Box 34110, Qatar
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18
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Thai LM, O’Reilly L, Reibe-Pal S, Sue N, Holliday H, Small L, Schmitz-Peiffer C, Dhenni R, Wang-Wei Tsai V, Norris N, Yau B, Zhang X, Lee K, Yan C, Shi YC, Kebede MA, Brink R, Cooney GJ, Irvine KM, Breit SN, Phan TG, Swarbrick A, Biden TJ. β-cell function is regulated by metabolic and epigenetic programming of islet-associated macrophages, involving Axl, Mertk, and TGFβ receptor signaling. iScience 2023; 26:106477. [PMID: 37091234 PMCID: PMC10113792 DOI: 10.1016/j.isci.2023.106477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 01/13/2023] [Accepted: 03/19/2023] [Indexed: 04/25/2023] Open
Abstract
We have exploited islet-associated macrophages (IAMs) as a model of resident macrophage function, focusing on more physiological conditions than the commonly used extremes of M1 (inflammation) versus M2 (tissue remodeling) polarization. Under steady state, murine IAMs are metabolically poised between aerobic glycolysis and oxidative phosphorylation, and thereby exert a brake on glucose-stimulated insulin secretion (GSIS). This is underpinned by epigenetic remodeling via the metabolically regulated histone demethylase Kdm5a. Conversely, GSIS is enhanced by engaging Axl receptors on IAMs, or by augmenting their oxidation of glucose. Following high-fat feeding, efferocytosis is stimulated in IAMs in conjunction with Mertk and TGFβ receptor signaling. This impairs GSIS and potentially contributes to β-cell failure in pre-diabetes. Thus, IAMs serve as relays in many more settings than currently appreciated, fine-tuning insulin secretion in response to dynamic changes in the external environment. Intervening in this nexus might represent a means of preserving β-cell function during metabolic disease.
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Affiliation(s)
- Le May Thai
- Garvan Institute of Medical Research, Sydney, NSW, Australia
| | - Liam O’Reilly
- Garvan Institute of Medical Research, Sydney, NSW, Australia
| | | | - Nancy Sue
- Garvan Institute of Medical Research, Sydney, NSW, Australia
| | - Holly Holliday
- Garvan Institute of Medical Research, Sydney, NSW, Australia
| | - Lewin Small
- Garvan Institute of Medical Research, Sydney, NSW, Australia
| | - Carsten Schmitz-Peiffer
- Garvan Institute of Medical Research, Sydney, NSW, Australia
- St Vincent’s Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, NSW, Australia
- School of Medical Sciences, Charles Perkins Centre, University of Sydney, Sydney, NSW, Australia
| | - Rama Dhenni
- Garvan Institute of Medical Research, Sydney, NSW, Australia
| | | | - Nicholas Norris
- School of Medical Sciences, Charles Perkins Centre, University of Sydney, Sydney, NSW, Australia
| | - Belinda Yau
- Centre for Applied Medical Research, Sydney, NSW, Australia
| | - Xuan Zhang
- Garvan Institute of Medical Research, Sydney, NSW, Australia
| | - Kailun Lee
- Garvan Institute of Medical Research, Sydney, NSW, Australia
| | - Chenxu Yan
- Garvan Institute of Medical Research, Sydney, NSW, Australia
| | - Yan-Chuan Shi
- Garvan Institute of Medical Research, Sydney, NSW, Australia
- St Vincent’s Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, NSW, Australia
| | - Melkam A. Kebede
- School of Medical Sciences, Charles Perkins Centre, University of Sydney, Sydney, NSW, Australia
| | - Robert Brink
- Garvan Institute of Medical Research, Sydney, NSW, Australia
- St Vincent’s Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, NSW, Australia
| | - Gregory J. Cooney
- Garvan Institute of Medical Research, Sydney, NSW, Australia
- St Vincent’s Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, NSW, Australia
- School of Medical Sciences, Charles Perkins Centre, University of Sydney, Sydney, NSW, Australia
| | | | - Samuel N. Breit
- St Vincent’s Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, NSW, Australia
- Centre for Applied Medical Research, Sydney, NSW, Australia
| | - Tri G. Phan
- Garvan Institute of Medical Research, Sydney, NSW, Australia
- St Vincent’s Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, NSW, Australia
| | - Alexander Swarbrick
- Garvan Institute of Medical Research, Sydney, NSW, Australia
- St Vincent’s Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, NSW, Australia
| | - Trevor J. Biden
- Garvan Institute of Medical Research, Sydney, NSW, Australia
- St Vincent’s Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, NSW, Australia
- Corresponding author
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19
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Mawla AM, van der Meulen T, Huising MO. Chromatin accessibility differences between alpha, beta, and delta cells identifies common and cell type-specific enhancers. BMC Genomics 2023; 24:202. [PMID: 37069576 PMCID: PMC10108528 DOI: 10.1186/s12864-023-09293-6] [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: 09/22/2022] [Accepted: 04/03/2023] [Indexed: 04/19/2023] Open
Abstract
BACKGROUND High throughput sequencing has enabled the interrogation of the transcriptomic landscape of glucagon-secreting alpha cells, insulin-secreting beta cells, and somatostatin-secreting delta cells. These approaches have furthered our understanding of expression patterns that define healthy or diseased islet cell types and helped explicate some of the intricacies between major islet cell crosstalk and glucose regulation. All three endocrine cell types derive from a common pancreatic progenitor, yet alpha and beta cells have partially opposing functions, and delta cells modulate and control insulin and glucagon release. While gene expression signatures that define and maintain cellular identity have been widely explored, the underlying epigenetic components are incompletely characterized and understood. However, chromatin accessibility and remodeling is a dynamic attribute that plays a critical role to determine and maintain cellular identity. RESULTS Here, we compare and contrast the chromatin landscape between mouse alpha, beta, and delta cells using ATAC-Seq to evaluate the significant differences in chromatin accessibility. The similarities and differences in chromatin accessibility between these related islet endocrine cells help define their fate in support of their distinct functional roles. We identify patterns that suggest that both alpha and delta cells are poised, but repressed, from becoming beta-like. We also identify patterns in differentially enriched chromatin that have transcription factor motifs preferentially associated with different regions of the genome. Finally, we not only confirm and visualize previously discovered common endocrine- and cell specific- enhancer regions across differentially enriched chromatin, but identify novel regions as well. We compiled our chromatin accessibility data in a freely accessible database of common endocrine- and cell specific-enhancer regions that can be navigated with minimal bioinformatics expertise. CONCLUSIONS Both alpha and delta cells appear poised, but repressed, from becoming beta cells in murine pancreatic islets. These data broadly support earlier findings on the plasticity in identity of non-beta cells under certain circumstances. Furthermore, differential chromatin accessibility shows preferentially enriched distal-intergenic regions in beta cells, when compared to either alpha or delta cells.
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Affiliation(s)
- Alex M Mawla
- Department of Neurobiology, Physiology & Behavior, College of Biological Sciences, University of California, One Shields Avenue, Davis, CA, 95616, USA
| | - Talitha van der Meulen
- Department of Neurobiology, Physiology & Behavior, College of Biological Sciences, University of California, One Shields Avenue, Davis, CA, 95616, USA
| | - Mark O Huising
- Department of Neurobiology, Physiology & Behavior, College of Biological Sciences, University of California, One Shields Avenue, Davis, CA, 95616, USA.
- Department of Physiology and Membrane Biology, School of Medicine, University of California, One Shields Avenue, Davis, CA, 95616, USA.
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20
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Viloria K, Nasteska D, Ast J, Hasib A, Cuozzo F, Heising S, Briant LJB, Hewison M, Hodson DJ. GC-Globulin/Vitamin D-Binding Protein Is Required for Pancreatic α-Cell Adaptation to Metabolic Stress. Diabetes 2023; 72:275-289. [PMID: 36445949 DOI: 10.2337/db22-0326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 11/14/2022] [Indexed: 12/02/2022]
Abstract
GC-globulin (GC), or vitamin D-binding protein, is a multifunctional protein involved in the transport of circulating vitamin 25(OH)D and fatty acids, as well as actin scavenging. In the pancreatic islets, the gene encoding GC, GC/Gc, is highly localized to glucagon-secreting α-cells. Despite this, the role of GC in α-cell function is poorly understood. We previously showed that GC is essential for α-cell morphology, electrical activity, and glucagon secretion. We now show that loss of GC exacerbates α-cell failure during metabolic stress. High-fat diet-fed GC-/- mice have basal hyperglucagonemia, which is associated with decreased α-cell size, impaired glucagon secretion and Ca2+ fluxes, and changes in glucose-dependent F-actin remodelling. Impairments in glucagon secretion can be rescued using exogenous GC to replenish α-cell GC levels, increase glucagon granule area, and restore the F-actin cytoskeleton. Lastly, GC levels decrease in α-cells of donors with type 2 diabetes, which is associated with changes in α-cell mass, morphology, and glucagon expression. Together, these data demonstrate an important role for GC in α-cell adaptation to metabolic stress.
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Affiliation(s)
- Katrina Viloria
- Institute of Metabolism and Systems Research (IMSR), and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, U.K
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, U.K
| | - Daniela Nasteska
- Institute of Metabolism and Systems Research (IMSR), and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, U.K
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, U.K
| | - Julia Ast
- Institute of Metabolism and Systems Research (IMSR), and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, U.K
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, U.K
| | - Annie Hasib
- Institute of Metabolism and Systems Research (IMSR), and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, U.K
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, U.K
| | - Federica Cuozzo
- Institute of Metabolism and Systems Research (IMSR), and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, U.K
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, U.K
| | - Silke Heising
- Institute of Metabolism and Systems Research (IMSR), and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, U.K
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, U.K
| | - Linford J B Briant
- Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), National Institute for Health Research (NIHR) Oxford Biomedical Research Centre, Churchill Hospital, Radcliffe Department of Medicine, University of Oxford, Oxford, U.K
| | - Martin Hewison
- Institute of Metabolism and Systems Research (IMSR), and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, U.K
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, U.K
| | - David J Hodson
- Institute of Metabolism and Systems Research (IMSR), and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, U.K
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, U.K
- Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), National Institute for Health Research (NIHR) Oxford Biomedical Research Centre, Churchill Hospital, Radcliffe Department of Medicine, University of Oxford, Oxford, U.K
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21
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Gross JD, Zhou Y, Barak LS, Caron MG. Ghrelin receptor signaling in health and disease: a biased view. Trends Endocrinol Metab 2023; 34:106-118. [PMID: 36567228 PMCID: PMC9852078 DOI: 10.1016/j.tem.2022.12.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 11/23/2022] [Accepted: 12/06/2022] [Indexed: 12/25/2022]
Abstract
As allosteric complexes, G-protein-coupled receptors (GPCRs) respond to extracellular stimuli and pleiotropically couple to intracellular transducers to elicit signaling pathway-dependent effects in a process known as biased signaling or functional selectivity. One such GPCR, the ghrelin receptor (GHSR1a), has a crucial role in restoring and maintaining metabolic homeostasis during disrupted energy balance. Thus, pharmacological modulation of GHSR1a bias could offer a promising strategy to treat several metabolism-based disorders. Here, we summarize current evidence supporting GHSR1a functional selectivity in vivo and highlight recent structural data. We propose that precise determinations of GHSR1a molecular pharmacology and pathway-specific physiological effects will enable discovery of GHSR1a drugs with tailored signaling profiles, thereby providing safer and more effective treatments for metabolic diseases.
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Affiliation(s)
- Joshua D Gross
- Department of Cell Biology, Duke University, Durham, NC 27710, USA
| | - Yang Zhou
- Department of Cell Biology, Duke University, Durham, NC 27710, USA
| | - Lawrence S Barak
- Department of Cell Biology, Duke University, Durham, NC 27710, USA.
| | - Marc G Caron
- Department of Cell Biology, Duke University, Durham, NC 27710, USA
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22
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Caniceiro AB, Bueschbell B, Schiedel AC, Moreira IS. Class A and C GPCR Dimers in Neurodegenerative Diseases. Curr Neuropharmacol 2022; 20:2081-2141. [PMID: 35339177 PMCID: PMC9886835 DOI: 10.2174/1570159x20666220327221830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 02/21/2022] [Accepted: 03/23/2022] [Indexed: 11/22/2022] Open
Abstract
Neurodegenerative diseases affect over 30 million people worldwide with an ascending trend. Most individuals suffering from these irreversible brain damages belong to the elderly population, with onset between 50 and 60 years. Although the pathophysiology of such diseases is partially known, it remains unclear upon which point a disease turns degenerative. Moreover, current therapeutics can treat some of the symptoms but often have severe side effects and become less effective in long-term treatment. For many neurodegenerative diseases, the involvement of G proteincoupled receptors (GPCRs), which are key players of neuronal transmission and plasticity, has become clearer and holds great promise in elucidating their biological mechanism. With this review, we introduce and summarize class A and class C GPCRs, known to form heterodimers or oligomers to increase their signalling repertoire. Additionally, the examples discussed here were shown to display relevant alterations in brain signalling and had already been associated with the pathophysiology of certain neurodegenerative diseases. Lastly, we classified the heterodimers into two categories of crosstalk, positive or negative, for which there is known evidence.
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Affiliation(s)
- Ana B. Caniceiro
- Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal; ,These authors contributed equally to this work.
| | - Beatriz Bueschbell
- PhD Programme in Experimental Biology and Biomedicine, Institute for Interdisciplinary Research (IIIUC), University of Coimbra, Casa Costa Alemão, 3030-789 Coimbra, Portugal; ,These authors contributed equally to this work.
| | - Anke C. Schiedel
- Department of Pharmaceutical & Medicinal Chemistry, Pharmaceutical Institute, University of Bonn, D-53121 Bonn, Germany;
| | - Irina S. Moreira
- University of Coimbra, Department of Life Sciences, Calçada Martim de Freitas, 3000-456 Coimbra, Portugal; ,Center for Neuroscience and Cell Biology, Center for Innovative Biomedicine and Biotechnology, 3004-504 Coimbra, Portugal,Address correspondence to this author at the Center for Neuroscience and Cell Biology, Center for Innovative Biomedicine and Biotechnology, 3004-504 Coimbra, Portugal; E-mail:
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23
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Du YQ, Sha XY, Cheng J, Wang J, Lin JY, An WT, Pan W, Zhang LJ, Tao XN, Xu YF, Jia YL, Yang Z, Xiao P, Liu M, Sun JP, Yu X. Endogenous Lipid-GPR120 Signaling Modulates Pancreatic Islet Homeostasis to Different Extents. Diabetes 2022; 71:1454-1471. [PMID: 35472681 DOI: 10.2337/db21-0794] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 04/04/2022] [Indexed: 11/13/2022]
Abstract
Long-chain fatty acids (LCFAs) are not only energy sources but also serve as signaling molecules. GPR120, an LCFA receptor, plays key roles in maintaining metabolic homeostasis. However, whether endogenous ligand-GPR120 circuits exist and how such circuits function in pancreatic islets are unclear. Here, we found that endogenous GPR120 activity in pancreatic δ-cells modulated islet functions. At least two unsaturated LCFAs, oleic acid (OA) and linoleic acid (LA), were identified as GPR120 agonists within pancreatic islets. These two LCFAs promoted insulin secretion by inhibiting somatostatin secretion and showed bias activation of GPR120 in a model system. Compared with OA, LA exerted higher potency in promoting insulin secretion, which is dependent on β-arrestin2 function. Moreover, GPR120 signaling was impaired in the diabetic db/db model, and replenishing OA and LA improved islet function in both the db/db and streptozotocin-treated diabetic models. Consistently, the administration of LA improved glucose metabolism in db/db mice. Collectively, our results reveal that endogenous LCFA-GPR120 circuits exist and modulate homeostasis in pancreatic islets. The contributions of phenotype differences caused by different LCFA-GPR120 circuits within islets highlight the roles of fine-tuned ligand-receptor signaling networks in maintaining islet homeostasis.
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Affiliation(s)
- Ya-Qin Du
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University, Key Laboratory of Molecular Cardiovascular Science, Ministry of Education, Beijing, China
- Key Laboratory Experimental Teratology of the Ministry of Education and Department of Physiology, School of Basic Medical Sciences, Shandong University, Jinan, Shandong, China
| | - Xue-Ying Sha
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University, Key Laboratory of Molecular Cardiovascular Science, Ministry of Education, Beijing, China
| | - Jie Cheng
- Key Laboratory Experimental Teratology of the Ministry of Education and Department of Physiology, School of Basic Medical Sciences, Shandong University, Jinan, Shandong, China
| | - Jin Wang
- Department of Pharmacology, School of Basic Medical Sciences, Shandong University, Jinan, Shandong, China
| | - Jing-Yu Lin
- Key Laboratory Experimental Teratology of the Ministry of Education and Department of Physiology, School of Basic Medical Sciences, Shandong University, Jinan, Shandong, China
| | - Wen-Tao An
- Key Laboratory Experimental Teratology of the Ministry of Education and Department of Physiology, School of Basic Medical Sciences, Shandong University, Jinan, Shandong, China
| | - Wei Pan
- Key Laboratory Experimental Teratology of the Ministry of Education and Department of Physiology, School of Basic Medical Sciences, Shandong University, Jinan, Shandong, China
| | - Li-Jun Zhang
- Key Laboratory Experimental Teratology of the Ministry of Education and Department of Physiology, School of Basic Medical Sciences, Shandong University, Jinan, Shandong, China
| | - Xiao-Na Tao
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Shandong University, Jinan, Shandong, China
| | - Yun-Fei Xu
- Department of General Surgery, Qilu Hospital of Shandong University, Jinan, Shandong, China
| | - Ying-Li Jia
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University, Key Laboratory of Molecular Cardiovascular Science, Ministry of Education, Beijing, China
| | - Zhao Yang
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Shandong University, Jinan, Shandong, China
| | - Peng Xiao
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Shandong University, Jinan, Shandong, China
| | - Ming Liu
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical School, Ann Arbor, MI
| | - Jin-Peng Sun
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University, Key Laboratory of Molecular Cardiovascular Science, Ministry of Education, Beijing, China
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Shandong University, Jinan, Shandong, China
| | - Xiao Yu
- Key Laboratory Experimental Teratology of the Ministry of Education and Department of Physiology, School of Basic Medical Sciences, Shandong University, Jinan, Shandong, China
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24
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Cho JH, Hughes JW. Cilia Action in Islets: Lessons From Mouse Models. Front Endocrinol (Lausanne) 2022; 13:922983. [PMID: 35813631 PMCID: PMC9260721 DOI: 10.3389/fendo.2022.922983] [Citation(s) in RCA: 0] [Impact Index Per Article: 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: 04/18/2022] [Accepted: 05/23/2022] [Indexed: 11/30/2022] Open
Abstract
Primary cilia as a signaling organelle have garnered recent attention as a regulator of pancreatic islet function. These rod-like sensors exist on all major islet endocrine cell types and transduce a variety of external cues, while dysregulation of cilia function contributes to the development of diabetes. The complex role of islet primary cilia has been examined using genetic deletion targeting various components of cilia. In this review, we summarize experimental models for the study of islet cilia and current understanding of mechanisms of cilia regulation of islet hormone secretion. Consensus from these studies shows that pancreatic cilia perturbation can cause both endocrine and exocrine defects that are relevant to human disease. We discuss future research directions that would further elucidate cilia action in distinct groups of islet cells, including paracrine and juxtacrine regulation, GPCR signaling, and endocrine-exocrine crosstalk.
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Affiliation(s)
| | - Jing W. Hughes
- Department of Medicine, Washington University School of Medicine, Saint Louis, MO, United States
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25
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Overton DL, Mastracci TL. Exocrine-Endocrine Crosstalk: The Influence of Pancreatic Cellular Communications on Organ Growth, Function and Disease. Front Endocrinol (Lausanne) 2022; 13:904004. [PMID: 35769082 PMCID: PMC9234176 DOI: 10.3389/fendo.2022.904004] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 04/26/2022] [Indexed: 12/12/2022] Open
Abstract
Diabetes mellitus, a disease that affects nearly 536.6 million people worldwide, is characterized by the death or dysfunction of insulin-producing beta cells of the pancreas. The beta cells are found within the islets of Langerhans, which are composed of multiple hormone-producing endocrine cells including the alpha (glucagon), delta (somatostatin), PP (pancreatic polypeptide), and epsilon (ghrelin) cells. There is direct evidence that physical and paracrine interactions between the cells in the islet facilitate and support beta cell function. However, communication between endocrine and exocrine cells in the pancreas may also directly impact beta cell growth and function. Herein we review literature that contributes to the view that "crosstalk" between neighboring cells within the pancreas influences beta cell growth and function and the maintenance of beta cell health.
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Affiliation(s)
- Danielle L. Overton
- Department of Biology, Indiana University-Purdue University Indianapolis, Indianapolis, IN, United States
| | - Teresa L. Mastracci
- Department of Biology, Indiana University-Purdue University Indianapolis, Indianapolis, IN, United States
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, United States
- Center for Diabetes and Metabolic Diseases, Indiana University School of Medicine, Indianapolis, IN, United States
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26
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Piper NBC, Whitfield EA, Stewart GD, Xu X, Furness SGB. Targeting appetite and satiety in diabetes and obesity, via G protein-coupled receptors. Biochem Pharmacol 2022; 202:115115. [PMID: 35671790 DOI: 10.1016/j.bcp.2022.115115] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 05/26/2022] [Accepted: 05/27/2022] [Indexed: 11/17/2022]
Abstract
Type 2 diabetes and obesity have reached pandemic proportions throughout the world, so much so that the World Health Organisation coined the term "Globesity" to help encapsulate the magnitude of the problem. G protein-coupled receptors (GPCRs) are highly tractable drug targets due to their wide involvement in all aspects of physiology and pathophysiology, indeed, GPCRs are the targets of approximately 30% of the currently approved drugs. GPCRs are also broadly involved in key physiologies that underlie type 2 diabetes and obesity including feeding reward, appetite and satiety, regulation of blood glucose levels, energy homeostasis and adipose function. Despite this, only two GPCRs are the target of approved pharmaceuticals for treatment of type 2 diabetes and obesity. In this review we discuss the role of these, and select other candidate GPCRs, involved in various facets of type 2 diabetic or obese pathophysiology, how they might be targeted and the potential reasons why pharmaceuticals against these targets have not progressed to clinical use. Finally, we provide a perspective on the current development pipeline of anti-obesity drugs that target GPCRs.
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Affiliation(s)
- Noah B C Piper
- Receptor Transducer Coupling Laboratory, School of Biomedical Sciences, Faculty of Medicine, University of Queensland, St. Lucia, QLD 4072, Australia
| | - Emily A Whitfield
- Receptor Transducer Coupling Laboratory, School of Biomedical Sciences, Faculty of Medicine, University of Queensland, St. Lucia, QLD 4072, Australia
| | - Gregory D Stewart
- Drug Discovery Biology Laboratory, Monash Institute of Pharmaceutical Sciences & Department of Pharmacology Monash University, Parkville, VIC 3052, Australia
| | - Xiaomeng Xu
- Drug Discovery Biology Laboratory, Monash Institute of Pharmaceutical Sciences & Department of Pharmacology Monash University, Parkville, VIC 3052, Australia
| | - Sebastian G B Furness
- Receptor Transducer Coupling Laboratory, School of Biomedical Sciences, Faculty of Medicine, University of Queensland, St. Lucia, QLD 4072, Australia; Drug Discovery Biology Laboratory, Monash Institute of Pharmaceutical Sciences & Department of Pharmacology Monash University, Parkville, VIC 3052, Australia.
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27
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Guccio N, Gribble FM, Reimann F. Glucose-Dependent Insulinotropic Polypeptide-A Postprandial Hormone with Unharnessed Metabolic Potential. Annu Rev Nutr 2022; 42:21-44. [PMID: 35609956 DOI: 10.1146/annurev-nutr-062320-113625] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Glucose-dependent insulinotropic polypeptide (GIP) is released from the upper small intestine in response to food intake and contributes to the postprandial control of nutrient disposition, including of sugars and fats. Long neglected as a potential therapeutic target, the GIPR axis has received increasing interest recently, with the emerging data demonstrating the metabolically favorable outcomes of adding GIPR agonism to GLP-1 receptor agonists in people with type 2 diabetes and obesity. This review examines the physiology of the GIP axis, from the mechanisms underlying GIP secretion from the intestine to its action on target tissues and therapeutic development. Expected final online publication date for the Annual Review of Nutrition, Volume 42 is August 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Nunzio Guccio
- MRC Metabolic Diseases Unit, Wellcome Trust/MRC Institute of Metabolic Science, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom; ,
| | - Fiona M Gribble
- MRC Metabolic Diseases Unit, Wellcome Trust/MRC Institute of Metabolic Science, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom; ,
| | - Frank Reimann
- MRC Metabolic Diseases Unit, Wellcome Trust/MRC Institute of Metabolic Science, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom; ,
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28
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Morriseau TS, Doucette CA, Dolinsky VW. More than meets the islet: aligning nutrient and paracrine inputs with hormone secretion in health and disease. Am J Physiol Endocrinol Metab 2022; 322:E446-E463. [PMID: 35373587 DOI: 10.1152/ajpendo.00411.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The pancreatic islet is responsive to an array of endocrine, paracrine, and nutritional inputs that adjust hormone secretion to ensure accurate control of glucose homeostasis. Although the mechanisms governing glucose-coupled insulin secretion have received the most attention, there is emerging evidence for a multitude of physiological signaling pathways and paracrine networks that collectively regulate insulin, glucagon, and somatostatin release. Moreover, the modulation of these pathways in conditions of glucotoxicity or lipotoxicity are areas of both growing interest and controversy. In this review, the contributions of external, intrinsic, and paracrine factors in pancreatic β-, α-, and δ-cell secretion across the full spectrum of physiological (i.e., fasting and fed) and pathophysiological (gluco- and lipotoxicity; diabetes) environments will be critically discussed.
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Affiliation(s)
- Taylor S Morriseau
- Diabetes Research Envisioned and Accomplished in Manitoba (DREAM) Theme of the Children's Hospital Research Institute of Manitoba, Winnipeg, Manitoba, Canada
- Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Christine A Doucette
- Diabetes Research Envisioned and Accomplished in Manitoba (DREAM) Theme of the Children's Hospital Research Institute of Manitoba, Winnipeg, Manitoba, Canada
- Department of Physiology and Pathophysiology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Vernon W Dolinsky
- Diabetes Research Envisioned and Accomplished in Manitoba (DREAM) Theme of the Children's Hospital Research Institute of Manitoba, Winnipeg, Manitoba, Canada
- Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, Manitoba, Canada
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29
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Thor D. G protein-coupled receptors as regulators of pancreatic islet functionality. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2022; 1869:119235. [PMID: 35151663 DOI: 10.1016/j.bbamcr.2022.119235] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 02/02/2022] [Accepted: 02/03/2022] [Indexed: 01/03/2023]
Abstract
Glucose homeostasis is maintained by hormones secreted from different types of pancreatic islets and its dysregulation can result in diseases including diabetes mellitus. The secretion of hormones from pancreatic islets is highly complex and tightly controlled by G protein-coupled receptors (GPCRs). Moreover, GPCR signaling may play a role in enhancing islet cell replication and proliferation. Thus, targeting GPCRs offers a promising strategy for regulating the functionality of pancreatic islets. Here, available RNAseq datasets from human and mouse islets were used to identify the GPCR expression profile and the impact of GPCR signaling for normal islet functionality is discussed.
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Affiliation(s)
- Doreen Thor
- Rudolf Schönheimer Institute of Biochemistry, Medical Faculty, Leipzig University, Johannisallee 30, 04103 Leipzig, Germany.
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30
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Hagemann CA, Jensen MS, Holm S, Gasbjerg LS, Byberg S, Skov-Jeppesen K, Hartmann B, Holst JJ, Dela F, Vilsbøll T, Christensen MB, Holst B, Knop FK. LEAP2 reduces postprandial glucose excursions and ad libitum food intake in healthy men. Cell Rep Med 2022; 3:100582. [PMID: 35492241 PMCID: PMC9043997 DOI: 10.1016/j.xcrm.2022.100582] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 01/24/2022] [Accepted: 02/28/2022] [Indexed: 12/12/2022]
Abstract
The gastric hormone ghrelin stimulates food intake and increases plasma glucose through activation of the growth hormone secretagogue receptor (GHSR). Liver-expressed antimicrobial peptide 2 (LEAP2) has been proposed to inhibit actions of ghrelin through inverse effects on GHSR activity. Here, we investigate the effects of exogenous LEAP2 on postprandial glucose metabolism and ad libitum food intake in a randomized, double-blind, placebo-controlled, crossover trial of 20 healthy men. We report that LEAP2 infusion lowers postprandial plasma glucose and growth hormone concentrations and decreases food intake during an ad libitum meal test. In wild-type mice, plasma glucose and food intake are reduced by LEAP2 dosing, but not in GHSR-null mice, pointing to GHSR as a potential mediator of LEAP2’s glucoregulatory and appetite-suppressing effects in mice. Exogenous LEAP2 lowers postprandial plasma glucose excursions Exogenous LEAP2 suppresses ad libitum food intake During fasting, exogenous LEAP2 increases insulin secretion and suppresses lipolysis The GHSR is required for eliciting LEAP2 effects in mice
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Affiliation(s)
- Christoffer A Hagemann
- Center for Clinical Metabolic Research, Copenhagen University Hospital Herlev and Gentofte, Hellerup, Denmark; Gubra, Hørsholm, Denmark
| | - Malene S Jensen
- Center for Clinical Metabolic Research, Copenhagen University Hospital Herlev and Gentofte, Hellerup, Denmark
| | - Stephanie Holm
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Lærke S Gasbjerg
- Center for Clinical Metabolic Research, Copenhagen University Hospital Herlev and Gentofte, Hellerup, Denmark; Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Sarah Byberg
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Kirsa Skov-Jeppesen
- 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
| | - 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
| | - Flemming Dela
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Tina Vilsbøll
- Center for Clinical Metabolic Research, Copenhagen University Hospital Herlev and Gentofte, Hellerup, Denmark; Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Steno Diabetes Center Copenhagen, Gentofte, Denmark
| | - Mikkel B Christensen
- Center for Clinical Metabolic Research, Copenhagen University Hospital Herlev and Gentofte, Hellerup, Denmark; Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Department of Clinical Pharmacology, Copenhagen University Hospital Bispebjerg and Frederiksberg, Copenhagen, Denmark
| | - Birgitte Holst
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
| | - Filip K Knop
- Center for Clinical Metabolic Research, Copenhagen University Hospital Herlev and Gentofte, Hellerup, Denmark; Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Steno Diabetes Center Copenhagen, Gentofte, Denmark.
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31
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Singh B, Khattab F, Gilon P. Glucose inhibits glucagon secretion by decreasing [Ca2+]c and by reducing the efficacy of Ca2+ on exocytosis via somatostatin-dependent and independent mechanisms. Mol Metab 2022; 61:101495. [PMID: 35421610 PMCID: PMC9065434 DOI: 10.1016/j.molmet.2022.101495] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 03/15/2022] [Accepted: 04/04/2022] [Indexed: 11/15/2022] Open
Abstract
Objective Methods Results Conclusions Glucose modulates [Ca2+]c in α-cells within islets but not in dispersed α-cells. In α-cells within islets, it decreases [Ca2+]c independently of their KATP channels. It decreases α-cell [Ca2+]c partly via somatostatin. All glucose-induced [Ca2+]c changes trigger parallel changes in glucagon release. Glucose also decreases the efficacy of Ca2+ on exocytosis (attenuating pathway).
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Affiliation(s)
- Bilal Singh
- Université Catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle d'Endocrinologie, Diabète et Nutrition, Brussels, Belgium
| | - Firas Khattab
- Université Catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle d'Endocrinologie, Diabète et Nutrition, Brussels, Belgium
| | - Patrick Gilon
- Université Catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle d'Endocrinologie, Diabète et Nutrition, Brussels, Belgium.
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32
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Guérineau NC, Campos P, Le Tissier PR, Hodson DJ, Mollard P. Cell Networks in Endocrine/Neuroendocrine Gland Function. Compr Physiol 2022; 12:3371-3415. [PMID: 35578964 DOI: 10.1002/cphy.c210031] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Reproduction, growth, stress, and metabolism are determined by endocrine/neuroendocrine systems that regulate circulating hormone concentrations. All these systems generate rhythms and changes in hormone pulsatility observed in a variety of pathophysiological states. Thus, the output of endocrine/neuroendocrine systems must be regulated within a narrow window of effective hormone concentrations but must also maintain a capacity for plasticity to respond to changing physiological demands. Remarkably most endocrinologists still have a "textbook" view of endocrine gland organization which has emanated from 20th century histological studies on thin 2D tissue sections. However, 21st -century technological advances, including in-depth 3D imaging of specific cell types have vastly changed our knowledge. We now know that various levels of multicellular organization can be found across different glands, that organizational motifs can vary between species and can be modified to enhance or decrease hormonal release. This article focuses on how the organization of cells regulates hormone output using three endocrine/neuroendocrine glands that present different levels of organization and complexity: the adrenal medulla, with a single neuroendocrine cell type; the anterior pituitary, with multiple intermingled cell types; and the pancreas with multiple intermingled cell types organized into distinct functional units. We give an overview of recent methodologies that allow the study of the different components within endocrine systems, particularly their temporal and spatial relationships. We believe the emerging findings about network organization, and its impact on hormone secretion, are crucial to understanding how homeostatic regulation of endocrine axes is carried out within endocrine organs themselves. © 2022 American Physiological Society. Compr Physiol 12:3371-3415, 2022.
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Affiliation(s)
| | - Pauline Campos
- College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, UK
| | - Paul R Le Tissier
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, Scotland, UK
| | - David J Hodson
- Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Edgbaston, UK.,Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, UK.,COMPARE University of Birmingham and University of Nottingham Midlands, UK.,Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), NIHR Oxford Biomedical Research Centre, Churchill Hospital, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Patrice Mollard
- IGF, University of Montpellier, CNRS, INSERM, Montpellier, France
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Acetyl-CoA-carboxylase 1 (ACC1) plays a critical role in glucagon secretion. Commun Biol 2022; 5:238. [PMID: 35304577 PMCID: PMC8933412 DOI: 10.1038/s42003-022-03170-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 02/08/2022] [Indexed: 11/09/2022] Open
Abstract
Dysregulated glucagon secretion from pancreatic alpha-cells is a key feature of type-1 and type-2 diabetes (T1D and T2D), yet our mechanistic understanding of alpha-cell function is underdeveloped relative to insulin-secreting beta-cells. Here we show that the enzyme acetyl-CoA-carboxylase 1 (ACC1), which couples glucose metabolism to lipogenesis, plays a key role in the regulation of glucagon secretion. Pharmacological inhibition of ACC1 in mouse islets or αTC9 cells impaired glucagon secretion at low glucose (1 mmol/l). Likewise, deletion of ACC1 in alpha-cells in mice reduced glucagon secretion at low glucose in isolated islets, and in response to fasting or insulin-induced hypoglycaemia in vivo. Electrophysiological recordings identified impaired KATP channel activity and P/Q- and L-type calcium currents in alpha-cells lacking ACC1, explaining the loss of glucose-sensing. ACC-dependent alterations in S-acylation of the KATP channel subunit, Kir6.2, were identified by acyl-biotin exchange assays. Histological analysis identified that loss of ACC1 caused a reduction in alpha-cell area of the pancreas, glucagon content and individual alpha-cell size, further impairing secretory capacity. Loss of ACC1 also reduced the release of glucagon-like peptide 1 (GLP-1) in primary gastrointestinal crypts. Together, these data reveal a role for the ACC1-coupled pathway in proglucagon-expressing nutrient-responsive endocrine cell function and systemic glucose homeostasis.
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Mechanistic Investigation of GHS-R Mediated Glucose-Stimulated Insulin Secretion in Pancreatic Islets. Biomolecules 2022; 12:biom12030407. [PMID: 35327599 PMCID: PMC8945998 DOI: 10.3390/biom12030407] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 02/19/2022] [Accepted: 02/27/2022] [Indexed: 02/07/2023] Open
Abstract
Ghrelin receptor, a growth hormone secretagogue receptor (GHS-R), is expressed in the pancreas. Emerging evidence indicates that GHS-R is involved in the regulation of glucose-stimulated insulin secretion (GSIS), but the mechanism by which GHS-R regulates GSIS in the pancreas is unclear. In this study, we investigated the role of GHS-R on GSIS in detail using global Ghsr−/− mice (in vivo) and Ghsr-ablated pancreatic islets (ex vivo). GSIS was attenuated in both Ghsr−/− mice and Ghsr-ablated islets, while the islet morphology was similar between WT and Ghsr−/− mice. To elucidate the mechanism underpinning Ghsr-mediated GSIS, we investigated the key steps of the GSIS signaling cascade. The gene expression of glucose transporter 2 (Glut2) and the glucose-metabolic intermediate—glucose-6-phosphate (G6P) were reduced in Ghsr-ablated islets, supporting decreased glucose uptake. There was no difference in mitochondrial DNA content in the islets of WT and Ghsr−/− mice, but the ATP/ADP ratio in Ghsr−/− islets was significantly lower than that of WT islets. Moreover, the expression of pancreatic and duodenal homeobox 1 (Pdx1), as well as insulin signaling genes of insulin receptor (IR) and insulin receptor substrates 1 and 2 (IRS1/IRS2), was downregulated in Ghsr−/− islets. Akt is the key mediator of the insulin signaling cascade. Concurrently, Akt phosphorylation was reduced in the pancreas of Ghsr−/− mice under both insulin-stimulated and homeostatic conditions. These findings demonstrate that GHS-R ablation affects key components of the insulin signaling pathway in the pancreas, suggesting the existence of a cross-talk between GHS-R and the insulin signaling pathway in pancreatic islets, and GHS-R likely regulates GSIS via the Akt-Pdx1-GLUT2 pathway.
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35
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Marinelli I, Parekh V, Fletcher P, Thompson B, Ren J, Tang X, Saunders TL, Ha J, Sherman A, Bertram R, Satin LS. Slow oscillations persist in pancreatic beta cells lacking phosphofructokinase M. Biophys J 2022; 121:692-704. [PMID: 35131294 PMCID: PMC8948000 DOI: 10.1016/j.bpj.2022.01.027] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 12/07/2021] [Accepted: 01/28/2022] [Indexed: 11/22/2022] Open
Abstract
Pulsatile insulin secretion by pancreatic beta cells is necessary for tight glucose control in the body. Glycolytic oscillations have been proposed as the mechanism for generating the electrical oscillations underlying pulsatile insulin secretion. The glycolytic enzyme 6-phosphofructokinase-1 (PFK) synthesizes fructose-1,6-bisphosphate (FBP) from fructose-6-phosphate. It has been proposed that the slow electrical and Ca2+ oscillations (periods of 3-5 min) observed in islets result from allosteric feedback activation of PFKM by FBP. Pancreatic beta cells express three PFK isozymes: PFKL, PFKM, and PFKP. A prior study of mice that were engineered to lack PFKM using a gene-trap strategy to delete Pfkm produced a mosaic reduction in global Pfkm expression, but the islets isolated from the mice still exhibited slow Ca2+ oscillations. However, these islets still expressed residual PFKM protein. Thus, to more fully test the hypothesis that beta cell PFKM is responsible for slow islet oscillations, we made a beta-cell-specific knockout mouse that completely lacked PFKM. While PFKM deletion resulted in subtle metabolic changes in vivo, islets that were isolated from these mice continued to exhibit slow oscillations in electrical activity, beta cell Ca2+ concentrations, and glycolysis, as measured using PKAR, an FBP reporter/biosensor. Furthermore, simulations obtained with a mathematical model of beta cell activity shows that slow oscillations can persist despite PFKM loss provided that one of the other PFK isoforms, such as PFKP, is present, even if its level of expression is unchanged. Thus, while we believe that PFKM may be the main regulator of slow oscillations in wild-type islets, PFKP can provide functional redundancy. Our model also suggests that PFKM likely dominates, in vivo, because it outcompetes PFKP with its higher FBP affinity and lower ATP affinity. We thus propose that isoform redundancy may rescue key physiological processes of the beta cell in the absence of certain critical genes.
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Affiliation(s)
- Isabella Marinelli
- Centre for Systems Modelling & Quantitative Biomedicine (SMQB), University of Birmingham, Birmingham, UK
| | - Vishal Parekh
- Department of Pharmacology and Brehm Center for Diabetes Research, University of Michigan Medical School, Ann Arbor, Michigan
| | - Patrick Fletcher
- Laboratory of Biological Modeling, National Institutes of Health, Bethesda, Bethesda
| | - Benjamin Thompson
- Department of Pharmacology and Brehm Center for Diabetes Research, University of Michigan Medical School, Ann Arbor, Michigan
| | - Jinhua Ren
- Department of Pharmacology and Brehm Center for Diabetes Research, University of Michigan Medical School, Ann Arbor, Michigan
| | - Xiaoqing Tang
- Department of Biological Sciences, Michigan Technological University, Houghton, Michigan
| | - Thomas L Saunders
- Division of Medical Medicine and Genetics, Department of Internal Medicine, Transgenic Animal Model Core, University of Michigan Medical School, Ann Arbor, Michigan
| | - Joon Ha
- Laboratory of Biological Modeling, National Institutes of Health, Bethesda, Bethesda
| | - Arthur Sherman
- Laboratory of Biological Modeling, National Institutes of Health, Bethesda, Bethesda
| | - Richard Bertram
- Department of Mathematics and Programs in Neuroscience and Molecular Biophysics, Florida State University, Tallahassee, Florida
| | - Leslie S Satin
- Department of Pharmacology and Brehm Center for Diabetes Research, University of Michigan Medical School, Ann Arbor, Michigan.
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36
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Andersen DB, Holst JJ. Peptides in the regulation of glucagon secretion. Peptides 2022; 148:170683. [PMID: 34748791 DOI: 10.1016/j.peptides.2021.170683] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 10/21/2021] [Accepted: 11/02/2021] [Indexed: 02/06/2023]
Abstract
Glucose homeostasis is maintained by the glucoregulatory hormones, glucagon, insulin and somatostatin, secreted from the islets of Langerhans. Glucagon is the body's most important anti-hypoglycemic hormone, mobilizing glucose from glycogen stores in the liver in response to fasting, thus maintaining plasma glucose levels within healthy limits. Glucagon secretion is regulated by both circulating nutrients, hormones and neuronal inputs. Hormones that may regulate glucagon secretion include locally produced insulin and somatostatin, but also urocortin-3, amylin and pancreatic polypeptide, and from outside the pancreas glucagon-like peptide-1 and 2, peptide tyrosine tyrosine and oxyntomodulin, glucose-dependent insulinotropic polypeptide, neurotensin and ghrelin, as well as the hypothalamic hormones arginine-vasopressin and oxytocin, and calcitonin from the thyroid. Each of these hormones have distinct effects, ranging from regulating blood glucose, to regulating appetite, stomach emptying rate and intestinal motility, which makes them interesting targets for treating metabolic diseases. Awareness regarding the potential effects of the hormones on glucagon secretion is important since secretory abnormalities could manifest as hyperglycemia or even lethal hypoglycemia. Here, we review the effects of each individual hormone on glucagon secretion, their interplay, and how treatments aimed at modulating the plasma levels of these hormones may also influence glucagon secretion and glycemic control.
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Affiliation(s)
- Daniel B Andersen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Panum Institute, Blegdamsvej 3B, 2200, Copenhagen N, Denmark; Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Jens J Holst
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Panum Institute, Blegdamsvej 3B, 2200, Copenhagen N, Denmark; Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark.
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37
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Dezaki K, Yada T. Status of ghrelin as an islet hormone and paracrine/autocrine regulator of insulin secretion. Peptides 2022; 148:170681. [PMID: 34728253 DOI: 10.1016/j.peptides.2021.170681] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 10/06/2021] [Accepted: 10/28/2021] [Indexed: 12/20/2022]
Abstract
Ghrelin is expressed in the pancreatic islet cells as well as the stomach. In the perfused pancreas and isolated islets, GHS-R antagonism, ghrelin immunoneutralization and ghrelin-knockout (Ghr-KO) all increase glucose-induced insulin release. Thus, pharmacological, immunological and genetic blockades of ghrelin in the pancreatic islets all markedly augment glucose-induced insulin release, showing that islet-derived ghrelin physiologically restricts insulin release in rodents. In this review, we focus on the current understanding of the following key questions: 1) from which islet cells ghrelin is released, 2) on which islet cells ghrelin acts, and 3) mechanisms by which the islet-derived ghrelin inhibits insulin secretion.
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Affiliation(s)
- Katsuya Dezaki
- Iryo Sosei University, Faculty of Pharmacy, 5-5-1, Chuodai Iino, Iwaki, Fukushima, 970-8551, Japan.
| | - Toshihiko Yada
- Kansai Electric Power Medical Research Institute, Center for Integrative Physiology, Division of Integrative Physiology, 1-5-6 Minatojimaminamimachi, Chuo-ku, Kobe, 650-0047, Japan; Division of Diabetes, Metabolism and Endocrinology, Kobe University Graduate School of Medicine, 7-5-2 Kusunoki-Cho, Chuo-Ku, Kobe, 650-0017, Japan.
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38
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Langlois A, Dumond A, Vion J, Pinget M, Bouzakri K. Crosstalk Communications Between Islets Cells and Insulin Target Tissue: The Hidden Face of Iceberg. Front Endocrinol (Lausanne) 2022; 13:836344. [PMID: 35185804 PMCID: PMC8851682 DOI: 10.3389/fendo.2022.836344] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 01/06/2022] [Indexed: 12/11/2022] Open
Abstract
The regulation of insulin secretion is under control of a complex inter-organ/cells crosstalk involving various metabolites and/or physical connections. In this review, we try to illustrate with current knowledge how β-cells communicate with other cell types and organs in physiological and pathological contexts. Moreover, this review will provide a better understanding of the microenvironment and of the context in which β-cells exist and how this can influence their survival and function. Recent studies showed that β-cell insulin secretion is regulated also by a direct and indirect inter-organ/inter-cellular communication involving various factors, illustrating the idea of "the hidden face of the iceberg". Moreover, any disruption on the physiological communication between β-cells and other cells or organs can participate on diabetes onset. Therefore, for new anti-diabetic treatments' development, it is necessary to consider the entire network of cells and organs involved in the regulation of β-cellular function and no longer just β-cell or pancreatic islet alone. In this context, we discuss here the intra-islet communication, the β-cell/skeletal muscle, β-cell/adipose tissue and β-cell/liver cross talk.
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39
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Miranda C, Begum M, Vergari E, Briant LJB. Gap junction coupling and islet delta-cell function in health and disease. Peptides 2022; 147:170704. [PMID: 34826505 DOI: 10.1016/j.peptides.2021.170704] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 11/12/2021] [Accepted: 11/19/2021] [Indexed: 12/12/2022]
Abstract
The pancreatic islets contain beta-cells and alpha-cells, which are responsible for secreting two principal gluco-regulatory hormones; insulin and glucagon, respectively. However, they also contain delta-cells, a relatively sparse cell type that secretes somatostatin (SST). These cells have a complex morphology allowing them to establish an extensive communication network throughout the islet, despite their scarcity. Delta-cells are electrically excitable cells, and SST secretion is released in a glucose- and KATP-dependent manner. SST hyperpolarises the alpha-cell membrane and suppresses exocytosis. In this way, islet SST potently inhibits glucagon release. Recent studies investigating the activity of delta-cells have revealed they are electrically coupled to beta-cells via gap junctions, suggesting the delta-cell is more than just a paracrine inhibitor. In this Review, we summarize delta-cell morphology, function, and the role of SST signalling for regulating islet hormonal output. A distinguishing feature of this Review is that we attempt to use the discovery of this gap junction pathway, together with what is already known about delta-cells, to reframe the role of these cells in both health and disease. In particular, we argue that the discovery of gap junction communication between delta-cells and beta-cells provides new insights into the contribution of delta-cells to the islet hormonal defects observed in both type 1 and type 2 diabetes. This reappraisal of the delta-cell is important as it may offer novel insights into how the physiology of this cell can be utilised to restore islet function in diabetes.
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Affiliation(s)
- Caroline Miranda
- Institute of Neuroscience and Physiology, Metabolic Research Unit, University of Göteborg, 405 30, Göteborg, Sweden
| | - Manisha Begum
- Institute of Neuroscience and Physiology, Metabolic Research Unit, University of Göteborg, 405 30, Göteborg, Sweden; University of Skӧvde, Department of Infection Biology, Högskolevägen 1, 541 28, Skövde, Sweden
| | - Elisa Vergari
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, OX4 7LE, Oxford, UK
| | - Linford J B Briant
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, OX4 7LE, Oxford, UK; Department of Computer Science, University of Oxford, OX1 3QD, Oxford, UK.
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40
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Deschaine SL, Leggio L. From "Hunger Hormone" to "It's Complicated": Ghrelin Beyond Feeding Control. Physiology (Bethesda) 2022; 37:5-15. [PMID: 34964687 PMCID: PMC8742734 DOI: 10.1152/physiol.00024.2021] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Discovered as a peptide involved in releasing growth hormone, ghrelin was initially characterized as the "hunger hormone." However, emerging research indicates that ghrelin appears to play an important part in relaying information regarding nutrient availability and value and adjusting physiological and motivational processes accordingly. These functions make ghrelin an interesting therapeutic candidate for metabolic and neuropsychiatric diseases involving disrupted nutrition that can further potentiate the rewarding effect of maladaptive behaviors.
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Affiliation(s)
- Sara L. Deschaine
- 1Clinical Psychoneuroendocrinology and Neuropsychopharmacology Section, Translational Addiction Medicine Branch, National Institute on Drug Abuse and National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Baltimore and Bethesda, Maryland
| | - Lorenzo Leggio
- 1Clinical Psychoneuroendocrinology and Neuropsychopharmacology Section, Translational Addiction Medicine Branch, National Institute on Drug Abuse and National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Baltimore and Bethesda, Maryland,2Medication Development Program, National Institute on Drug Abuse Intramural Research Program, National Institutes of Health, Baltimore, Maryland,3Center for Alcohol and Addiction Studies, Department of Behavioral and Social Sciences, School of Public Health, Brown University, Providence, Rhode Island,4Division of Addiction Medicine, Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, Maryland,5Department of Neuroscience, Georgetown University Medical Center, Washington, District of Columbia
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41
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Ast J, Broichhagen J, Hodson DJ. Reagents and models for detecting endogenous GLP1R and GIPR. EBioMedicine 2021; 74:103739. [PMID: 34911028 PMCID: PMC8669301 DOI: 10.1016/j.ebiom.2021.103739] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 11/12/2021] [Accepted: 11/23/2021] [Indexed: 01/18/2023] Open
Abstract
Glucagon-like peptide-1 receptor (GLP1R) agonists target the GLP1R, whereas dual GLP1R/ gastric inhibitory polypeptide receptor (GIPR) agonists target both the GLP1R and GIPR. Despite the importance of these drug classes for the treatment of diabetes and obesity, still very little is known about the localization of GLP1R and GIPR themselves. Complicating matters is the low abundance of GLP1R and GIPR mRNA/protein, as well as a lack of specific and validated reagents for their detection. Without knowing where GLP1R and GIPR are located, it is difficult to propose mechanisms of action in the various target organs, and whether this is indirect or direct. In the current review, we will explain the steps needed to properly validate reagents for endogenous GLP1R/GIPR detection, describe the available approaches to visualize GLP1R/GIPR, and provide an update on the state-of-art. The overall aim is to provide a reference resource for researchers interested in GLP1R and GIPR signaling.
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Affiliation(s)
- Julia Ast
- Institute of Metabolism and Systems Research (IMSR), Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, UK; Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, UK
| | | | - David J Hodson
- Institute of Metabolism and Systems Research (IMSR), Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, UK; Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, UK.
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42
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Price ML, Ley CD, Gorvin CM. The emerging role of heterodimerisation and interacting proteins in ghrelin receptor function. J Endocrinol 2021; 252:R23-R39. [PMID: 34663757 PMCID: PMC8630777 DOI: 10.1530/joe-21-0206] [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: 09/05/2021] [Accepted: 10/18/2021] [Indexed: 11/14/2022]
Abstract
Ghrelin is a peptide hormone secreted primarily by the stomach that acts upon the growth hormone secretagogue receptor (GHSR1), a G protein-coupled receptor whose functions include growth hormone secretion, appetite regulation, energy expenditure, regulation of adiposity, and insulin release. Following the discovery that GHSR1a stimulates food intake, receptor antagonists were developed as potential therapies to regulate appetite. However, despite reductions in signalling, the desired effects on appetite were absent. Studies in the past 15 years have demonstrated GHSR1a can interact with other transmembrane proteins, either by direct binding (i.e. heteromerisation) or via signalling cross-talk. These interactions have various effects on GHSR1a signalling including preferential coupling to one pathway (i.e. biased signalling), coupling to a unique G protein (G protein switching), suppression of GHSR1a signalling, and enhancement of signalling by both receptors. While many of these interactions have been shown in cells overexpressing the proteins of interest and remain to be verified in tissues, substantial evidence exists showing that GHSR1a and the dopamine receptor D1 (DRD1) form heteromers, which promote synaptic plasticity and formation of hippocampal memory. Additionally, a reduction in GHSR1a-DRD1 complexes in favour of establishment of GHSR1a-Aβ complexes correlates with Alzheimer's disease, indicating that GHSR1a heteromers may have pathological functions. Herein, we summarise the evidence published to date describing interactions between GHSR1a and transmembrane proteins, discuss the experimental strengths and limitations of these studies, describe the physiological evidence for each interaction, and address their potential as novel drug targets for appetite regulation, Alzheimer's disease, insulin secretion, and inflammation.
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Affiliation(s)
- Maria L Price
- Institute of Metabolism and Systems Research and Centre for Endocrinology, Diabetes and Metabolism, University of Birmingham, Birmingham, UK
- Centre of Membrane Proteins and Receptors (COMPARE), Universities of Birmingham and Nottingham, Birmingham, UK
| | - Cameron D Ley
- Institute of Metabolism and Systems Research and Centre for Endocrinology, Diabetes and Metabolism, University of Birmingham, Birmingham, UK
- Centre of Membrane Proteins and Receptors (COMPARE), Universities of Birmingham and Nottingham, Birmingham, UK
| | - Caroline M Gorvin
- Institute of Metabolism and Systems Research and Centre for Endocrinology, Diabetes and Metabolism, University of Birmingham, Birmingham, UK
- Centre of Membrane Proteins and Receptors (COMPARE), Universities of Birmingham and Nottingham, Birmingham, UK
- Correspondence should be addressed to C M Gorvin:
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Somatostatin and Its Receptor System in Colorectal Cancer. Biomedicines 2021; 9:biomedicines9111743. [PMID: 34829972 PMCID: PMC8615525 DOI: 10.3390/biomedicines9111743] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 11/19/2021] [Accepted: 11/20/2021] [Indexed: 12/14/2022] Open
Abstract
Somatostatin (SST)/somatotropin release-inhibiting factor (SRIF) is a well-known neuropeptide, widely distributed in the central and peripheral nervous systems, that regulates the endocrine system and affects neurotransmission via interaction with five SST receptors (SST1-5). In the gastrointestinal tract, the main SST-producing cells include intestinal enteroendocrine cells (EECs) restricted to the mucosa, and neurons of the submucosal and myenteric plexuses. The action of the SRIF system is based on the inhibition of endocrine and exocrine secretion, as well as the proliferative responses of target cells. The SST1–5 share common signaling pathways, and are not only widely expressed on normal tissues, but also frequently overexpressed by several tumors, particularly neuroendocrine neoplasms (NENs). Furthermore, the SRIF system represents the only peptide/G protein-coupled receptor (GPCR) system with multiple approved clinical applications for the diagnosis and treatment of several NENs. The role of the SRIF system in the histogenesis of colorectal cancer (CRC) subtypes (e.g., adenocarcinoma and signet ring-cell carcinoma), as well as diagnosis and prognosis of mixed adenoneuroendocrine carcinoma (MANEC) and pure adenocarcinoma, is poorly understood. Moreover, the impact of the SRIF system signaling on CRC cell proliferation and its potential role in the progression of this cancer remains unknown. Therefore, this review summarizes the recent collective knowledge and understanding of the clinical significance of the SRIF system signaling in CRC, aiming to evaluate the potential role of its components in CRC histogenesis, diagnosis, and potential therapy.
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Napolitano T, Avolio F, Silvano S, Forcisi S, Pfeifer A, Vieira A, Navarro-Sanz S, Friano ME, Ayachi C, Garrido-Utrilla A, Atlija J, Hadzic B, Becam J, Sousa-De-Veiga A, Plaisant MD, Balaji S, Pisani DF, Mondin M, Schmitt-Kopplin P, Amri EZ, Collombat P. Gfi1 Loss Protects against Two Models of Induced Diabetes. Cells 2021; 10:cells10112805. [PMID: 34831029 PMCID: PMC8616283 DOI: 10.3390/cells10112805] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 10/07/2021] [Accepted: 10/14/2021] [Indexed: 12/29/2022] Open
Abstract
Background: Although several approaches have revealed much about individual factors that regulate pancreatic development, we have yet to fully understand their complicated interplay during pancreas morphogenesis. Gfi1 is transcription factor specifically expressed in pancreatic acinar cells, whose role in pancreas cells fate identity and specification is still elusive. Methods: In order to gain further insight into the function of this factor in the pancreas, we generated animals deficient for Gfi1 specifically in the pancreas. Gfi1 conditional knockout animals were phenotypically characterized by immunohistochemistry, RT-qPCR, and RNA scope. To assess the role of Gfi1 in the pathogenesis of diabetes, we challenged Gfi1-deficient mice with two models of induced hyperglycemia: long-term high-fat/high-sugar feeding and streptozotocin injections. Results: Interestingly, mutant mice did not show any obvious deleterious phenotype. However, in depth analyses demonstrated a significant decrease in pancreatic amylase expression, leading to a diminution in intestinal carbohydrates processing and thus glucose absorption. In fact, Gfi1-deficient mice were found resistant to diet-induced hyperglycemia, appearing normoglycemic even after long-term high-fat/high-sugar diet. Another feature observed in mutant acinar cells was the misexpression of ghrelin, a hormone previously suggested to exhibit anti-apoptotic effects on β-cells in vitro. Impressively, Gfi1 mutant mice were found to be resistant to the cytotoxic and diabetogenic effects of high-dose streptozotocin administrations, displaying a negligible loss of β-cells and an imperturbable normoglycemia. Conclusions: Together, these results demonstrate that Gfi1 could turn to be extremely valuable for the development of new therapies and could thus open new research avenues in the context of diabetes research.
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Affiliation(s)
- Tiziana Napolitano
- Faculté des Sciences, Université Côte d’Azur, CNRS, Inserm, iBV, Parc Valrose, 06108 Nice, France; (T.N.); (S.S.); (A.P.); (A.V.); (M.E.F.); (C.A.); (A.G.-U.); (J.B.); (A.S.-D.-V.); (M.D.P.); (E.-Z.A.)
| | - Fabio Avolio
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense, Denmark;
| | - Serena Silvano
- Faculté des Sciences, Université Côte d’Azur, CNRS, Inserm, iBV, Parc Valrose, 06108 Nice, France; (T.N.); (S.S.); (A.P.); (A.V.); (M.E.F.); (C.A.); (A.G.-U.); (J.B.); (A.S.-D.-V.); (M.D.P.); (E.-Z.A.)
| | - Sara Forcisi
- Research Unit Analytical BioGeoChemistry, Helmholtz Zentrum München, German Research Center for Environment Health, 85764 Neuherberg, Germany; (S.F.); (P.S.-K.)
- German Center for Diabetes Research (DZD), 85764 Neuherberg, Germany
| | - Anja Pfeifer
- Faculté des Sciences, Université Côte d’Azur, CNRS, Inserm, iBV, Parc Valrose, 06108 Nice, France; (T.N.); (S.S.); (A.P.); (A.V.); (M.E.F.); (C.A.); (A.G.-U.); (J.B.); (A.S.-D.-V.); (M.D.P.); (E.-Z.A.)
| | - Andhira Vieira
- Faculté des Sciences, Université Côte d’Azur, CNRS, Inserm, iBV, Parc Valrose, 06108 Nice, France; (T.N.); (S.S.); (A.P.); (A.V.); (M.E.F.); (C.A.); (A.G.-U.); (J.B.); (A.S.-D.-V.); (M.D.P.); (E.-Z.A.)
| | | | - Marika Elsa Friano
- Faculté des Sciences, Université Côte d’Azur, CNRS, Inserm, iBV, Parc Valrose, 06108 Nice, France; (T.N.); (S.S.); (A.P.); (A.V.); (M.E.F.); (C.A.); (A.G.-U.); (J.B.); (A.S.-D.-V.); (M.D.P.); (E.-Z.A.)
| | - Chaïma Ayachi
- Faculté des Sciences, Université Côte d’Azur, CNRS, Inserm, iBV, Parc Valrose, 06108 Nice, France; (T.N.); (S.S.); (A.P.); (A.V.); (M.E.F.); (C.A.); (A.G.-U.); (J.B.); (A.S.-D.-V.); (M.D.P.); (E.-Z.A.)
| | - Anna Garrido-Utrilla
- Faculté des Sciences, Université Côte d’Azur, CNRS, Inserm, iBV, Parc Valrose, 06108 Nice, France; (T.N.); (S.S.); (A.P.); (A.V.); (M.E.F.); (C.A.); (A.G.-U.); (J.B.); (A.S.-D.-V.); (M.D.P.); (E.-Z.A.)
| | | | - Biljana Hadzic
- Pediatric Oncology & Hematology Department, Centre Hospitalier Universitaire de Nice, Hopital Archet 2, 06202 Nice, France;
| | - Jérôme Becam
- Faculté des Sciences, Université Côte d’Azur, CNRS, Inserm, iBV, Parc Valrose, 06108 Nice, France; (T.N.); (S.S.); (A.P.); (A.V.); (M.E.F.); (C.A.); (A.G.-U.); (J.B.); (A.S.-D.-V.); (M.D.P.); (E.-Z.A.)
| | - Anette Sousa-De-Veiga
- Faculté des Sciences, Université Côte d’Azur, CNRS, Inserm, iBV, Parc Valrose, 06108 Nice, France; (T.N.); (S.S.); (A.P.); (A.V.); (M.E.F.); (C.A.); (A.G.-U.); (J.B.); (A.S.-D.-V.); (M.D.P.); (E.-Z.A.)
| | - Magali Dodille Plaisant
- Faculté des Sciences, Université Côte d’Azur, CNRS, Inserm, iBV, Parc Valrose, 06108 Nice, France; (T.N.); (S.S.); (A.P.); (A.V.); (M.E.F.); (C.A.); (A.G.-U.); (J.B.); (A.S.-D.-V.); (M.D.P.); (E.-Z.A.)
| | | | - Didier F. Pisani
- Medicine Faculty, Université Côte d’Azur, CNRS, LP2M, 06003 Nice, France;
| | - Magali Mondin
- Pôle Imagerie Photonique, Bordeaux Imaging Center, Université de Bordeaux, UMS 3420 CNRS-US4 Inserm, 33076 Bordeaux, France;
| | - Philippe Schmitt-Kopplin
- Research Unit Analytical BioGeoChemistry, Helmholtz Zentrum München, German Research Center for Environment Health, 85764 Neuherberg, Germany; (S.F.); (P.S.-K.)
- German Center for Diabetes Research (DZD), 85764 Neuherberg, Germany
| | - Ez-Zoubir Amri
- Faculté des Sciences, Université Côte d’Azur, CNRS, Inserm, iBV, Parc Valrose, 06108 Nice, France; (T.N.); (S.S.); (A.P.); (A.V.); (M.E.F.); (C.A.); (A.G.-U.); (J.B.); (A.S.-D.-V.); (M.D.P.); (E.-Z.A.)
| | - Patrick Collombat
- Faculté des Sciences, Université Côte d’Azur, CNRS, Inserm, iBV, Parc Valrose, 06108 Nice, France; (T.N.); (S.S.); (A.P.); (A.V.); (M.E.F.); (C.A.); (A.G.-U.); (J.B.); (A.S.-D.-V.); (M.D.P.); (E.-Z.A.)
- Correspondence:
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Gupta D, Dowsett GKC, Mani BK, Shankar K, Osborne-Lawrence S, Metzger NP, Lam BYH, Yeo GSH, Zigman JM. High Coexpression of the Ghrelin and LEAP2 Receptor GHSR With Pancreatic Polypeptide in Mouse and Human Islets. Endocrinology 2021; 162:6325122. [PMID: 34289060 PMCID: PMC8379901 DOI: 10.1210/endocr/bqab148] [Citation(s) in RCA: 10] [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: 06/06/2021] [Indexed: 02/07/2023]
Abstract
Islets represent an important site of direct action of the hormone ghrelin, with expression of the ghrelin receptor (growth hormone secretagogue receptor; GHSR) having been localized variably to alpha cells, beta cells, and/or somatostatin (SST)-secreting delta cells. To our knowledge, GHSR expression by pancreatic polypeptide (PP)-expressing gamma cells has not been specifically investigated. Here, histochemical analyses of Ghsr-IRES-Cre × Cre-dependent ROSA26-yellow fluorescent protein (YFP) reporter mice showed 85% of GHSR-expressing islet cells coexpress PP, 50% coexpress SST, and 47% coexpress PP + SST. Analysis of single-cell transcriptomic data from mouse pancreas revealed 95% of Ghsr-expressing cells coexpress Ppy, 100% coexpress Sst, and 95% coexpress Ppy + Sst. This expression was restricted to gamma-cell and delta-cell clusters. Analysis of several single-cell human pancreatic transcriptome data sets revealed 59% of GHSR-expressing cells coexpress PPY, 95% coexpress SST, and 57% coexpress PPY + SST. This expression was prominent in delta-cell and beta-cell clusters, also occurring in other clusters including gamma cells and alpha cells. GHSR expression levels were upregulated by type 2 diabetes mellitus in beta cells. In mice, plasma PP positively correlated with fat mass and with plasma levels of the endogenous GHSR antagonist/inverse agonist LEAP2. Plasma PP also elevated on LEAP2 and synthetic GHSR antagonist administration. These data suggest that in addition to delta cells, beta cells, and alpha cells, PP-expressing pancreatic cells likely represent important direct targets for LEAP2 and/or ghrelin both in mice and humans.
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Affiliation(s)
- Deepali Gupta
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9077, USA
| | - Georgina K C Dowsett
- Medical Research Council (MRC) Metabolic Diseases Unit, University of Cambridge Metabolic Research Laboratories, Wellcome Trust–MRC Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge CB2 0QQ, UK
| | - Bharath K Mani
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9077, USA
| | - Kripa Shankar
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9077, USA
| | - Sherri Osborne-Lawrence
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9077, USA
| | - Nathan P Metzger
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9077, USA
| | - Brian Y H Lam
- Medical Research Council (MRC) Metabolic Diseases Unit, University of Cambridge Metabolic Research Laboratories, Wellcome Trust–MRC Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge CB2 0QQ, UK
| | - Giles S H Yeo
- Medical Research Council (MRC) Metabolic Diseases Unit, University of Cambridge Metabolic Research Laboratories, Wellcome Trust–MRC Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge CB2 0QQ, UK
- Correspondence: Giles S. H. Yeo, PhD, Metabolic Diseases Unit, University of Cambridge Metabolic Research Laboratories, Wellcome–MRC Institute of Metabolic Science, Box 289, Addenbrooke’s Hospital, Hills Rd, Cambridge, CB2 0QQ, UK.
| | - Jeffrey M Zigman
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9077, USA
- Division of Endocrinology, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9077, USA
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9077, USA
- Correspondence: Jeffrey M. Zigman, MD, PhD, Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, MC9077, Dallas, TX 75390-9077, USA.
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Galvin SG, Kay RG, Foreman R, Larraufie P, Meek CL, Biggs E, Ravn P, Jermutus L, Reimann F, Gribble FM. The Human and Mouse Islet Peptidome: Effects of Obesity and Type 2 Diabetes, and Assessment of Intraislet Production of Glucagon-like Peptide-1. J Proteome Res 2021; 20:4507-4517. [PMID: 34423991 PMCID: PMC8419866 DOI: 10.1021/acs.jproteome.1c00463] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Indexed: 02/07/2023]
Abstract
To characterize the impact of metabolic disease on the peptidome of human and mouse pancreatic islets, LC-MS was used to analyze extracts of human and mouse islets, purified mouse alpha, beta, and delta cells, supernatants from mouse islet incubations, and plasma from patients with type 2 diabetes. Islets were obtained from healthy and type 2 diabetic human donors, and mice on chow or high fat diet. All major islet hormones were detected in lysed islets as well as numerous peptides from vesicular proteins including granins and processing enzymes. Glucose-dependent insulinotropic peptide (GIP) was not detectable. High fat diet modestly increased islet content of proinsulin-derived peptides in mice. Human diabetic islets contained increased content of proglucagon-derived peptides at the expense of insulin, but no evident prohormone processing defects. Diabetic plasma, however, contained increased ratios of proinsulin and des-31,32-proinsulin to insulin. Active GLP-1 was detectable in human and mouse islets but 100-1000-fold less abundant than glucagon. LC-MS offers advantages over antibody-based approaches for identifying exact peptide sequences, and revealed a shift toward islet insulin production in high fat fed mice, and toward proglucagon production in type 2 diabetes, with no evidence of systematic defective prohormone processing.
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Affiliation(s)
- Sam G. Galvin
- University
of Cambridge Metabolic Research Laboratories, WT-MRC Institute of Metabolic Science, Addenbrooke’s
Hospital, Hills Road, Cambridge, CB2 0QQ, U.K.
| | - Richard G. Kay
- University
of Cambridge Metabolic Research Laboratories, WT-MRC Institute of Metabolic Science, Addenbrooke’s
Hospital, Hills Road, Cambridge, CB2 0QQ, U.K.
| | - Rachel Foreman
- University
of Cambridge Metabolic Research Laboratories, WT-MRC Institute of Metabolic Science, Addenbrooke’s
Hospital, Hills Road, Cambridge, CB2 0QQ, U.K.
| | - Pierre Larraufie
- University
of Cambridge Metabolic Research Laboratories, WT-MRC Institute of Metabolic Science, Addenbrooke’s
Hospital, Hills Road, Cambridge, CB2 0QQ, U.K.
| | - Claire L. Meek
- University
of Cambridge Metabolic Research Laboratories, WT-MRC Institute of Metabolic Science, Addenbrooke’s
Hospital, Hills Road, Cambridge, CB2 0QQ, U.K.
| | - Emma Biggs
- University
of Cambridge Metabolic Research Laboratories, WT-MRC Institute of Metabolic Science, Addenbrooke’s
Hospital, Hills Road, Cambridge, CB2 0QQ, U.K.
| | - Peter Ravn
- Research
and Early Development Cardiovascular, Renal and Metabolism (CVRM),
BioPharmaceuticals R&D, AstraZeneca
Ltd., Cambridge, CB21 6GH, U.K.
| | - Lutz Jermutus
- Research
and Early Development Cardiovascular, Renal and Metabolism (CVRM),
BioPharmaceuticals R&D, AstraZeneca
Ltd., Cambridge, CB21 6GH, U.K.
| | - Frank Reimann
- University
of Cambridge Metabolic Research Laboratories, WT-MRC Institute of Metabolic Science, Addenbrooke’s
Hospital, Hills Road, Cambridge, CB2 0QQ, U.K.
| | - Fiona M. Gribble
- University
of Cambridge Metabolic Research Laboratories, WT-MRC Institute of Metabolic Science, Addenbrooke’s
Hospital, Hills Road, Cambridge, CB2 0QQ, U.K.
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Shankar K, Takemi S, Gupta D, Varshney S, Mani BK, Osborne-Lawrence S, Metzger NP, Richard CP, Berglund ED, Zigman JM. Ghrelin cell-expressed insulin receptors mediate meal- and obesity-induced declines in plasma ghrelin. JCI Insight 2021; 6:e146983. [PMID: 34473648 PMCID: PMC8492315 DOI: 10.1172/jci.insight.146983] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 08/04/2021] [Indexed: 01/20/2023] Open
Abstract
Mechanisms underlying postprandial and obesity-associated plasma ghrelin reductions are incompletely understood. Here, using ghrelin cell-selective insulin receptor-KO (GhIRKO) mice, we tested the impact of insulin, acting via ghrelin cell-expressed insulin receptors (IRs), to suppress ghrelin secretion. Insulin reduced ghrelin secretion from cultured gastric mucosal cells of control mice but not from those of GhIRKO mice. Acute insulin challenge and insulin infusion during both hyperinsulinemic-hypoglycemic clamps and hyperinsulinemic-euglycemic clamps lowered plasma ghrelin in control mice but not GhIRKO mice. Thus, ghrelin cell-expressed IRs are required for insulin-mediated reductions in plasma ghrelin. Furthermore, interventions that naturally raise insulin (glucose gavage, refeeding following fasting, and chronic high-fat diet) also lowered plasma ghrelin only in control mice - not GhIRKO mice. Thus, meal- and obesity-associated increases in insulin, acting via ghrelin cell-expressed IRs, represent a major, direct negative modulator of ghrelin secretion in vivo, as opposed to ingested or metabolized macronutrients. Refed GhIRKO mice exhibited reduced plasma insulin, highlighting ghrelin's actions to inhibit insulin release via a feedback loop. Moreover, GhIRKO mice required reduced glucose infusion rates during hyperinsulinemic-hypoglycemic clamps, suggesting that suppressed ghrelin release resulting from direct insulin action on ghrelin cells usually limits ghrelin's full potential to protect against insulin-induced hypoglycemia.
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Affiliation(s)
- Kripa Shankar
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Shota Takemi
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
- Area of Regulatory Biology, Division of Life Science, Graduate School of Science and Engineering, Saitama University, Sakuraku, Saitama, Japan
| | - Deepali Gupta
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Salil Varshney
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Bharath K. Mani
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Sherri Osborne-Lawrence
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Nathan P. Metzger
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Corine P. Richard
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Eric D. Berglund
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Jeffrey M. Zigman
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
- Division of Endocrinology, Department of Internal Medicine, and
- Department of Psychiatry, UT Southwestern Medical Center, Dallas, Texas, USA
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Kaczmarek I, Suchý T, Prömel S, Schöneberg T, Liebscher I, Thor D. The relevance of adhesion G protein-coupled receptors in metabolic functions. Biol Chem 2021; 403:195-209. [PMID: 34218541 DOI: 10.1515/hsz-2021-0146] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Accepted: 06/08/2021] [Indexed: 01/06/2023]
Abstract
G protein-coupled receptors (GPCRs) modulate a variety of physiological functions and have been proven to be outstanding drug targets. However, approximately one-third of all non-olfactory GPCRs are still orphans in respect to their signal transduction and physiological functions. Receptors of the class of Adhesion GPCRs (aGPCRs) are among these orphan receptors. They are characterized by unique features in their structure and tissue-specific expression, which yields them interesting candidates for deorphanization and testing as potential therapeutic targets. Capable of G-protein coupling and non-G protein-mediated function, aGPCRs may extend our repertoire of influencing physiological function. Besides their described significance in the immune and central nervous systems, growing evidence indicates a high importance of these receptors in metabolic tissue. RNAseq analyses revealed high expression of several aGPCRs in pancreatic islets, adipose tissue, liver, and intestine but also in neurons governing food intake. In this review, we focus on aGPCRs and their function in regulating metabolic pathways. Based on current knowledge, this receptor class represents high potential for future pharmacological approaches addressing obesity and other metabolic diseases.
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Affiliation(s)
- Isabell Kaczmarek
- Rudolf Schönheimer Institute of Biochemistry, Medical Faculty, Leipzig University, Johannisallee 30, D-04103 Leipzig, Germany
| | - Tomáš Suchý
- Rudolf Schönheimer Institute of Biochemistry, Medical Faculty, Leipzig University, Johannisallee 30, D-04103 Leipzig, Germany
| | - Simone Prömel
- Rudolf Schönheimer Institute of Biochemistry, Medical Faculty, Leipzig University, Johannisallee 30, D-04103 Leipzig, Germany
- Institute of Cell Biology, Heinrich Heine University Düsseldorf, D-40225 Düsseldorf, Germany
| | - Torsten Schöneberg
- Rudolf Schönheimer Institute of Biochemistry, Medical Faculty, Leipzig University, Johannisallee 30, D-04103 Leipzig, Germany
| | - Ines Liebscher
- Rudolf Schönheimer Institute of Biochemistry, Medical Faculty, Leipzig University, Johannisallee 30, D-04103 Leipzig, Germany
| | - Doreen Thor
- Rudolf Schönheimer Institute of Biochemistry, Medical Faculty, Leipzig University, Johannisallee 30, D-04103 Leipzig, Germany
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Holst JJ, Gasbjerg LS, Rosenkilde MM. The Role of Incretins on Insulin Function and Glucose Homeostasis. Endocrinology 2021; 162:6199910. [PMID: 33782700 PMCID: PMC8168943 DOI: 10.1210/endocr/bqab065] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Indexed: 12/14/2022]
Abstract
The incretin effect-the amplification of insulin secretion after oral vs intravenous administration of glucose as a mean to improve glucose tolerance-was suspected even before insulin was discovered, and today we know that the effect is due to the secretion of 2 insulinotropic peptides, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1). But how important is it? Physiological experiments have shown that, because of the incretin effect, we can ingest increasing amounts of amounts of glucose (carbohydrates) without increasing postprandial glucose excursions, which otherwise might have severe consequences. The mechanism behind this is incretin-stimulated insulin secretion. The availability of antagonists for GLP-1 and most recently also for GIP has made it possible to directly estimate the individual contributions to postprandial insulin secretion of a) glucose itself: 26%; b) GIP: 45%; and c) GLP-1: 29%. Thus, in healthy individuals, GIP is the champion. When the action of both incretins is prevented, glucose tolerance is pathologically impaired. Thus, after 100 years of research, we now know that insulinotropic hormones from the gut are indispensable for normal glucose tolerance. The loss of the incretin effect in type 2 diabetes, therefore, contributes greatly to the impaired postprandial glucose control.
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Affiliation(s)
- Jens Juul Holst
- Department of Biomedical Sciences and the NovoNordisk Center for Basic Metabolic Research, Faculty of Health Sciences, University of Copenhagen, The Panum Institute, Copenhagen N, DK-2200 Denmark
- Correspondence: Jens Juul Holst, MD, University of Copenhagen, Department of Biomedical Sciences, The Panum Institute, 3 Blegdamsvej, Copenhagen, DK-2200 Denmark.
| | - Lærke Smidt Gasbjerg
- Department of Biomedical Sciences and the NovoNordisk Center for Basic Metabolic Research, Faculty of Health Sciences, University of Copenhagen, The Panum Institute, Copenhagen N, DK-2200 Denmark
| | - Mette Marie Rosenkilde
- Department of Biomedical Sciences and the NovoNordisk Center for Basic Metabolic Research, Faculty of Health Sciences, University of Copenhagen, The Panum Institute, Copenhagen N, DK-2200 Denmark
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Pancreatic β Cells Inhibit Glucagon Secretion from α Cells: An In Vitro Demonstration of α-β Cell Interaction. Nutrients 2021; 13:nu13072281. [PMID: 34209449 PMCID: PMC8308288 DOI: 10.3390/nu13072281] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 06/25/2021] [Accepted: 06/27/2021] [Indexed: 12/24/2022] Open
Abstract
Interactions between endocrine α and β cells are critical to their secretory function in vivo. The interactions are highly regulated, although yet to be fully understood. In this study, we aim to assess the impact of α and β cell co-culture on hormone secretion. Mouse clonal cell lines α-TC6-1 (α cell line) and MIN-6 (β cell line) were cultured independently or in combination in a medium containing 5.5, 11.1, or 25 mM glucose, respectively. After 72 h, hormone release was measured using insulin and glucagon secretion assays, the cell distribution was visualized by inverted microscopy and an immunocytochemistry assay, and changes in gene expressions were assessed using the RT-PCR technique. The co-culture of the two cell lines caused a decrease in glucagon secretion from α-TC1-6 cells, while no effect on insulin secretion from MIN-6 cells was revealed. Both types of cells were randomly scattered throughout the culture flask, unlike in mice islets in vivo where β cells cluster in the core and α cells are localized at the periphery. During the α-β cell co-culture, the gene expression of glucagon (Gcg) decreased significantly. We conclude that islet β cells suppress glucagon secretion from α cells, apparently via direct cell-to-cell contact, of which the molecular mechanism needs further verification.
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