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Wang C, Abadpour S, Aizenshtadt A, Dalmao-Fernandez A, Høyem M, Wilhelmsen I, Stokowiec J, Olsen PA, Krauss S, Chera S, Ghila L, Ræder H, Scholz H. Cell identity dynamics and insight into insulin secretagogues when employing stem cell-derived islets for disease modeling. Front Bioeng Biotechnol 2024; 12:1392575. [PMID: 38933536 PMCID: PMC11199790 DOI: 10.3389/fbioe.2024.1392575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Accepted: 05/13/2024] [Indexed: 06/28/2024] Open
Abstract
Stem cell-derived islets (SC-islets) are not only an unlimited source for cell-based therapy of type 1 diabetes but have also emerged as an attractive material for modeling diabetes and conducting screening for treatment options. Prior to SC-islets becoming the established standard for disease modeling and drug development, it is essential to understand their response to various nutrient sources in vitro. This study demonstrates an enhanced efficiency of pancreatic endocrine cell differentiation through the incorporation of WNT signaling inhibition following the definitive endoderm stage. We have identified a tri-hormonal cell population within SC-islets, which undergoes reduction concurrent with the emergence of elevated numbers of glucagon-positive cells during extended in vitro culture. Over a 6-week period of in vitro culture, the SC-islets consistently demonstrated robust insulin secretion in response to glucose stimulation. Moreover, they manifested diverse reactivity patterns when exposed to distinct nutrient sources and exhibited deviant glycolytic metabolic characteristics in comparison to human primary islets. Although the SC-islets demonstrated an aberrant glucose metabolism trafficking, the evaluation of a potential antidiabetic drug, pyruvate kinase agonist known as TEPP46, significantly improved in vitro insulin secretion of SC-islets. Overall, this study provided cell identity dynamics investigation of SC-islets during prolonged culturing in vitro, and insights into insulin secretagogues. Associated advantages and limitations were discussed when employing SC-islets for disease modeling.
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Affiliation(s)
- Chencheng Wang
- Department of Transplant Medicine and Institute for Surgical Research, Oslo University Hospital, Oslo, Norway
- Hybrid Technology Hub, Center of Excellence, University of Oslo, Oslo, Norway
| | - Shadab Abadpour
- Department of Transplant Medicine and Institute for Surgical Research, Oslo University Hospital, Oslo, Norway
- Hybrid Technology Hub, Center of Excellence, University of Oslo, Oslo, Norway
| | | | - Andrea Dalmao-Fernandez
- Hybrid Technology Hub, Center of Excellence, University of Oslo, Oslo, Norway
- Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, University of Oslo, Oslo, Norway
| | - Merete Høyem
- Department of Transplant Medicine and Institute for Surgical Research, Oslo University Hospital, Oslo, Norway
| | - Ingrid Wilhelmsen
- Hybrid Technology Hub, Center of Excellence, University of Oslo, Oslo, Norway
- Department of Immunology and Transfusion Medicine, Oslo University Hospital, Oslo, Norway
| | - Justyna Stokowiec
- Hybrid Technology Hub, Center of Excellence, University of Oslo, Oslo, Norway
| | - Petter Angell Olsen
- Hybrid Technology Hub, Center of Excellence, University of Oslo, Oslo, Norway
- Department of Immunology and Transfusion Medicine, Oslo University Hospital, Oslo, Norway
| | - Stefan Krauss
- Hybrid Technology Hub, Center of Excellence, University of Oslo, Oslo, Norway
- Department of Immunology and Transfusion Medicine, Oslo University Hospital, Oslo, Norway
| | - Simona Chera
- Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Luiza Ghila
- Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Helge Ræder
- Department of Clinical Science, University of Bergen, Bergen, Norway
- Department of Pediatrics, Haukeland University Hospital, Bergen, Norway
| | - Hanne Scholz
- Department of Transplant Medicine and Institute for Surgical Research, Oslo University Hospital, Oslo, Norway
- Hybrid Technology Hub, Center of Excellence, University of Oslo, Oslo, Norway
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Tamarit-Rodriguez J. Regulatory Role of Fatty Acid Metabolism on Glucose-Induced Changes in Insulin and Glucagon Secretion by Pancreatic Islet Cells. Int J Mol Sci 2024; 25:6052. [PMID: 38892240 PMCID: PMC11172437 DOI: 10.3390/ijms25116052] [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: 04/17/2024] [Revised: 05/21/2024] [Accepted: 05/26/2024] [Indexed: 06/21/2024] Open
Abstract
A detailed study of palmitate metabolism in pancreatic islets subject to different experimental conditions, like varying concentrations of glucose, as well as fed or starved conditions, has allowed us to explore the interaction between the two main plasma nutrients and its consequences on hormone secretion. Palmitate potentiates glucose-induced insulin secretion in a concentration-dependent manner, in a physiological range of both palmitate (0-2 mM) and glucose (6-20 mM) concentrations; at glucose concentrations lower than 6 mM, no metabolic interaction with palmitate was apparent. Starvation (48 h) increased islet palmitate oxidation two-fold, and the effect was resistant to its inhibition by glucose (6-20 mM). Consequently, labelled palmitate and glucose incorporation into complex lipids were strongly suppressed, as well as glucose-induced insulin secretion and its potentiation by palmitate. 2-bromostearate, a palmitate oxidation inhibitor, fully recovered the synthesis of complex lipids and insulin secretion. We concluded that palmitate potentiation of the insulin response to glucose is not attributable to its catabolic mitochondrial oxidation but to its anabolism to complex lipids: islet lipid biosynthesis is dependent on the uptake of plasma fatty acids and the supply of α-glycerol phosphate from glycolysis. Islet secretion of glucagon and somatostatin showed a similar dependence on palmitate anabolism as insulin. The possible mechanisms implicated in the metabolic coupling between glucose and palmitate were commented on. Moreover, possible mechanisms responsible for islet gluco- or lipotoxicity after a long-term stimulation of insulin secretion were also discussed. Our own data on the simultaneous stimulation of insulin, glucagon, and somatostatin by glucose, as well as their modification by 2-bromostearate in perifused rat islets, give support to the conclusion that increased FFA anabolism, rather than its mitochondrial oxidation, results in a potentiation of their stimulated release. Starvation, besides suppressing glucose stimulation of insulin secretion, also blocks the inhibitory effect of glucose on glucagon secretion: this suggests that glucagon inhibition might be an indirect or direct effect of insulin, but not of glucose. In summary, there seems to exist three mechanisms of glucagon secretion stimulation: 1. glucagon stimulation through the same secretion coupling mechanism as insulin, but in a different range of glucose concentrations (0 to 5 mM). 2. Direct or indirect inhibition by secreted insulin in response to glucose (5-20 mM). 3. Stimulation by increased FFA anabolism in glucose intolerance or diabetes in the context of hyperlipidemia, hyperglycemia, and hypo-insulinemia. These conclusions were discussed and compared with previous published data in the literature. Specially, we discussed the mechanism for inhibition of glucagon release by glucose, which was apparently contradictory with the secretion coupling mechanism of its stimulation.
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Liu W, Zhu M, Liu J, Su S, Zeng X, Fu F, Lu Y, Rao Z, Chen Y. Comparison of the effects of monounsaturated fatty acids and polyunsaturated fatty acids on the lipotoxicity of islets. Front Endocrinol (Lausanne) 2024; 15:1368853. [PMID: 38501107 PMCID: PMC10945794 DOI: 10.3389/fendo.2024.1368853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Accepted: 02/12/2024] [Indexed: 03/20/2024] Open
Abstract
Background Monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs) have been reported to combat saturated fatty acid (SFA)-induced cellular damage, however, their clinical effects on patients with metabolic diseases such as diabetes and hyperlipidemia are still controversial. Since comparative studies of the effects of these two types of unsaturated fatty acids (UFAs) are still limited. In this study, we aimed to compare the protective effects of various UFAs on pancreatic islets under the stress of SFA-induced metabolic disorder and lipotoxicity. Methods Rat insulinoma cell line INS-1E were treated with palmitic acid (PA) with or without UFAs including eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), arachidonic acid (AA), and oleic acid (OA) to determine cell viability, apoptosis, endoplasmic reticulum (ER) stress, and inflammatory. In vivo, male C57BL/6 mice were fed a 60% high-fat diet (HFD) for 12 w. Then the lard in HFD was partially replaced with fish oil (FO) and olive oil (OO) at low or high proportions of energy (5% or 20%) to observe the ameliorative effects of the UFA supplement. Results All UFAs significantly improved PA-induced cell viability impairment in INS-1E cells, and their alleviation on PA induced apoptosis, ER stress and inflammation were confirmed. Particularly, OA had better effects than EPA, DHA, and AA on attenuating cellular ER stress. In vivo, the diets with a low proportion of UFAs (5% of energy) had limited effects on HFD induced metabolic disorder, except for a slight improved intraperitoneal glucose tolerance in obese mice. However, when fed diets containing a high proportion of UFAs (20% of energy), both the FO and OO groups exhibited substantially improved glucose and lipid metabolism, such as decrease in total cholesterol (TC), low-density lipoprotein (LDL), fasting blood glucose (FBG), and fasting blood insulin (FBI)) and improvement of insulin sensitivity evidenced by intraperitoneal glucose tolerance test (IPGTT) and intraperitoneal insulin tolerance test (IPITT). Unexpectedly, FO resulted in abnormal elevation of the liver function index aspartate aminotransferase (AST) in serum. Pathologically, OO attenuated HFD-induced compensatory hyperplasia of pancreatic islets, while this effect was not obvious in the FO group. Conclusions Both MUFAs and PUFAs can effectively protect islet β cells from SFA-induced cellular lipotoxicity. In particular, both OA in vitro and OO in vivo showed superior activities on protecting islets function and enhance insulin sensitivity, suggesting that MUFAs might have greater potential for nutritional intervention on diabetes.
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Affiliation(s)
- Wen Liu
- Department of Clinical Nutrition and Key Laboratory of Transplant Engineering and Immunology, Regenerative Medicine Research Center, West China Hospital, Sichuan University, Chengdu, China
| | - Min Zhu
- Department of Clinical Nutrition and Key Laboratory of Transplant Engineering and Immunology, Regenerative Medicine Research Center, West China Hospital, Sichuan University, Chengdu, China
| | - Jingyi Liu
- Institutes for Systems Genetics, Frontiers Science Center for Disease-related Molecular Network, West China Hospital, Sichuan University, Chengdu, China
| | - Shan Su
- Institutes for Systems Genetics, Frontiers Science Center for Disease-related Molecular Network, West China Hospital, Sichuan University, Chengdu, China
| | - Xin Zeng
- Institutes for Systems Genetics, Frontiers Science Center for Disease-related Molecular Network, West China Hospital, Sichuan University, Chengdu, China
| | - Fudong Fu
- Institutes for Systems Genetics, Frontiers Science Center for Disease-related Molecular Network, West China Hospital, Sichuan University, Chengdu, China
| | - Yanrong Lu
- Department of Clinical Nutrition and Key Laboratory of Transplant Engineering and Immunology, Regenerative Medicine Research Center, West China Hospital, Sichuan University, Chengdu, China
| | - Zhiyong Rao
- Department of Clinical Nutrition, West China Hospital, Sichuan University, Chengdu, China
| | - Younan Chen
- Department of Clinical Nutrition and Key Laboratory of Transplant Engineering and Immunology, Regenerative Medicine Research Center, West China Hospital, Sichuan University, Chengdu, China
- Institutes for Systems Genetics, Frontiers Science Center for Disease-related Molecular Network, West China Hospital, Sichuan University, Chengdu, China
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Zhang W, Miura A, Abu Saleh MM, Shimizu K, Mita Y, Tanida R, Hirako S, Shioda S, Gmyr V, Kerr-Conte J, Pattou F, Jin C, Kanai Y, Sasaki K, Minamino N, Sakoda H, Nakazato M. The NERP-4-SNAT2 axis regulates pancreatic β-cell maintenance and function. Nat Commun 2023; 14:8158. [PMID: 38071217 PMCID: PMC10710447 DOI: 10.1038/s41467-023-43976-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2022] [Accepted: 11/23/2023] [Indexed: 12/18/2023] Open
Abstract
Insulin secretion from pancreatic β cells is regulated by multiple stimuli, including nutrients, hormones, neuronal inputs, and local signalling. Amino acids modulate insulin secretion via amino acid transporters expressed on β cells. The granin protein VGF has dual roles in β cells: regulating secretory granule formation and functioning as a multiple peptide precursor. A VGF-derived peptide, neuroendocrine regulatory peptide-4 (NERP-4), increases Ca2+ influx in the pancreata of transgenic mice expressing apoaequorin, a Ca2+-induced bioluminescent protein complex. NERP-4 enhances glucose-stimulated insulin secretion from isolated human and mouse islets and β-cell-derived MIN6-K8 cells. NERP-4 administration reverses the impairment of β-cell maintenance and function in db/db mice by enhancing mitochondrial function and reducing metabolic stress. NERP-4 acts on sodium-coupled neutral amino acid transporter 2 (SNAT2), thereby increasing glutamine, alanine, and proline uptake into β cells and stimulating insulin secretion. SNAT2 deletion and inhibition abolish the protective effects of NERP-4 on β-cell maintenance. These findings demonstrate a novel autocrine mechanism of β-cell maintenance and function that is mediated by the peptide-amino acid transporter axis.
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Affiliation(s)
- Weidong Zhang
- Department of Bioregulatory Sciences, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
- Division of Neurology, Respirology, Endocrinology and Metabolism, Department of Internal Medicine, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
| | - Ayako Miura
- Division of Neurology, Respirology, Endocrinology and Metabolism, Department of Internal Medicine, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
- Department of Pharmacology, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
| | - Md Moin Abu Saleh
- Division of Neurology, Respirology, Endocrinology and Metabolism, Department of Internal Medicine, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
- Department of Postgraduate Studies and Research, Royal College of Surgeons in Ireland - Bahrain, Busaiteen, Bahrain
| | - Koichiro Shimizu
- Division of Neurology, Respirology, Endocrinology and Metabolism, Department of Internal Medicine, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
- Division of Hematology, Diabetes, and Endocrinology, Department of Internal Medicine, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
| | - Yuichiro Mita
- Division of Neurology, Respirology, Endocrinology and Metabolism, Department of Internal Medicine, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
- Systems Life Sciences Laboratory, Department of Medical Life Systems, Faculty of Life and Medical Sciences, Doshisha University, Kyoto, Japan
| | - Ryota Tanida
- Division of Neurology, Respirology, Endocrinology and Metabolism, Department of Internal Medicine, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
- Department of Endocrinology and Metabolism, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Satoshi Hirako
- Department of Health and Nutrition, University of Human Arts and Sciences, Saitama, Japan
| | - Seiji Shioda
- Department of Clinical Pharmacy, Faculty of Pharmaceutical Sciences, Shonan University of Medical Sciences, Yokohama, Japan
| | - Valery Gmyr
- Université de Lille, Inserm, Campus Hospitalo-Universitaire de Lille, Institut Pasteur de Lille, U1190-EGID, F-59000, Lille, France
| | - Julie Kerr-Conte
- Université de Lille, Inserm, Campus Hospitalo-Universitaire de Lille, Institut Pasteur de Lille, U1190-EGID, F-59000, Lille, France
| | - Francois Pattou
- Université de Lille, Inserm, Campus Hospitalo-Universitaire de Lille, Institut Pasteur de Lille, U1190-EGID, F-59000, Lille, France
| | - Chunhuan Jin
- Department of Bio-system Pharmacology, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Yoshikatsu Kanai
- Department of Bio-system Pharmacology, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Kazuki Sasaki
- Department of Peptidomics, Sasaki Foundation, Tokyo, Japan
| | - Naoto Minamino
- Department of Molecular Pharmacology, National Cerebral and Cardiovascular Center Research, Suita, Japan
| | - Hideyuki Sakoda
- Department of Bioregulatory Sciences, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
- Division of Neurology, Respirology, Endocrinology and Metabolism, Department of Internal Medicine, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
| | - Masamitsu Nakazato
- Department of Bioregulatory Sciences, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan.
- Division of Neurology, Respirology, Endocrinology and Metabolism, Department of Internal Medicine, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan.
- Institute for Protein Research, Osaka University, Osaka, Japan.
- AMED-CREST, Japan Agency for Medical Research and Development, Tokyo, Japan.
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Thomas P, Gallagher MT, Da Silva Xavier G. Beta cell lipotoxicity in the development of type 2 diabetes: the need for species-specific understanding. Front Endocrinol (Lausanne) 2023; 14:1275835. [PMID: 38144558 PMCID: PMC10739424 DOI: 10.3389/fendo.2023.1275835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Accepted: 11/13/2023] [Indexed: 12/26/2023] Open
Abstract
The propensity to develop type 2 diabetes (T2D) is known to have both environmental and hereditary components. In those with a genetic predisposition to T2D, it is widely believed that elevated concentrations of circulatory long-chain fatty acids (LC-FFA) significantly contribute towards the demise of insulin-producing pancreatic β-cells - the fundamental feature of the development of T2D. Over 25 years of research support that LC-FFA are deleterious to β-cells, through a process termed lipotoxicity. However, the work underpinning the theory of β-cell lipotoxicity is mostly based on rodent studies. Doubts have been raised as to whether lipotoxicity also occurs in humans. In this review, we examine the evidence, both in vivo and in vitro, for the pathogenic effects of LC-FFA on β-cell viability and function in humans, highlighting key species differences. In this way, we aim to uncover the role of lipotoxicity in the human pathogenesis of T2D and motivate the need for species-specific understanding.
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Affiliation(s)
- Patricia Thomas
- Centre for Systems Modelling and Quantitative Biomedicine, University of Birmingham, Birmingham, United Kingdom
- Institute for Metabolism and Systems Research, Birmingham Medical School, University of Birmingham, Birmingham, United Kingdom
| | - Meurig T. Gallagher
- Centre for Systems Modelling and Quantitative Biomedicine, University of Birmingham, Birmingham, United Kingdom
- Institute for Metabolism and Systems Research, Birmingham Medical School, University of Birmingham, Birmingham, United Kingdom
| | - Gabriela Da Silva Xavier
- Institute for Metabolism and Systems Research, Birmingham Medical School, University of Birmingham, Birmingham, United Kingdom
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Zhang J, Zheng Y, Martens L, Pfeiffer AFH. The Regulation and Secretion of Glucagon in Response to Nutrient Composition: Unraveling Their Intricate Mechanisms. Nutrients 2023; 15:3913. [PMID: 37764697 PMCID: PMC10536047 DOI: 10.3390/nu15183913] [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: 08/01/2023] [Revised: 08/31/2023] [Accepted: 09/06/2023] [Indexed: 09/29/2023] Open
Abstract
Glucagon was initially regarded as a hyperglycemic substance; however, recent research has revealed its broader role in metabolism, encompassing effects on glucose, amino acids (AAs), and lipid metabolism. Notably, the interplay of glucagon with nutrient intake, particularly of AAs, and non-nutrient components is central to its secretion. Fasting and postprandial hyperglucagonemia have long been linked to the development and progression of type 2 diabetes (T2DM). However, recent studies have brought to light the positive impact of glucagon agonists on lipid metabolism and energy homeostasis. This review explores the multifaceted actions of glucagon, focusing on its regulation, signaling pathways, and effects on glucose, AAs, and lipid metabolism. The interplay between glucagon and other hormones, including insulin and incretins, is examined to provide a mechanistic understanding of its functions. Notably, the liver-α-cell axis, which involves glucagon and amino acids, emerges as a critical aspect of metabolic regulation. The dysregulation of glucagon secretion and its impact on conditions such as T2DM are discussed. The review highlights the potential therapeutic applications of targeting the glucagon pathway in the treatment of metabolic disorders.
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Affiliation(s)
- Jiudan Zhang
- The First Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou 310053, China;
- Department of Endocrinology, Diabetes and Nutrition, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10117 Berlin, Germany; (L.M.); (A.F.H.P.)
| | - Yang Zheng
- The First Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou 310053, China;
| | - Lisa Martens
- Department of Endocrinology, Diabetes and Nutrition, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10117 Berlin, Germany; (L.M.); (A.F.H.P.)
- Nutritional Science, University of Potsdam, 14469 Potsdam, Germany
| | - Andreas F. H. Pfeiffer
- Department of Endocrinology, Diabetes and Nutrition, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10117 Berlin, Germany; (L.M.); (A.F.H.P.)
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7
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Armour SL, Stanley JE, Cantley J, Dean ED, Knudsen JG. Metabolic regulation of glucagon secretion. J Endocrinol 2023; 259:e230081. [PMID: 37523232 PMCID: PMC10681275 DOI: 10.1530/joe-23-0081] [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: 03/17/2023] [Accepted: 07/31/2023] [Indexed: 08/01/2023]
Abstract
Since the discovery of glucagon 100 years ago, the hormone and the pancreatic islet alpha cells that produce it have remained enigmatic relative to insulin-producing beta cells. Canonically, alpha cells have been described in the context of glucagon's role in glucose metabolism in liver, with glucose as the primary nutrient signal regulating alpha cell function. However, current data reveal a more holistic model of metabolic signalling, involving glucagon-regulated metabolism of multiple nutrients by the liver and other tissues, including amino acids and lipids, providing reciprocal feedback to regulate glucagon secretion and even alpha cell mass. Here we describe how various nutrients are sensed, transported and metabolised in alpha cells, providing an integrative model for the metabolic regulation of glucagon secretion and action. Importantly, we discuss where these nutrient-sensing pathways intersect to regulate alpha cell function and highlight key areas for future research.
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Affiliation(s)
- Sarah L Armour
- Section for cell biology and physiology, Department of Biology, University of Copenhagen, DK
| | - Jade E. Stanley
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, USA
| | - James Cantley
- Division of Cellular and systems medicine, School of Medicine, University of Dundee, UK
| | - E. Danielle Dean
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, USA
- Division of Diabetes, Endocrinology, & Metabolism, Vanderbilt University Medical Center school of medicine, USA
| | - Jakob G Knudsen
- Section for cell biology and physiology, Department of Biology, University of Copenhagen, DK
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Stenlid R, Manell H, Seth R, Cerenius SY, Chowdhury A, Roa Cortés C, Nyqvist I, Lundqvist T, Halldin M, Bergsten P. Low Fasting Concentrations of Glucagon in Patients with Very Long-Chain Acyl-CoA Dehydrogenase Deficiency. Metabolites 2023; 13:780. [PMID: 37512487 PMCID: PMC10386500 DOI: 10.3390/metabo13070780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 06/18/2023] [Accepted: 06/21/2023] [Indexed: 07/30/2023] Open
Abstract
(1) Background: Deficiencies of mitochondrial fatty acid oxidation (FAO) define a subgroup of inborn errors of metabolism, with medium-chain acyl-CoA dehydrogenase deficiency (MCAD) and very long-chain acyl-CoA dehydrogenase deficiency (VLCAD) being two of the most common. Hypoketotic hypoglycemia is a feared clinical complication and the treatment focuses on avoiding hypoglycemia. In contrast, carnitine uptake deficiency (CUD) is treated as a mild disease without significant effects on FAO. Impaired FAO has experimentally been shown to impair glucagon secretion. Glucagon is an important glucose-mobilizing hormone. If and how glucagon is affected in patients with VLCAD or MCAD remains unknown. (2) Methods: A cross-sectional study was performed with plasma hormone concentrations quantified after four hours of fasting. Patients with VLCAD (n = 10), MCAD (n = 7) and CUD (n = 6) were included. (3) Results: The groups were similar in age, sex, weight, and height. The glucagon and insulin levels were significantly lower in the VLCAD group compared to the CUD group (p < 0.05, respectively). The patients with CUD had glucagon concentrations similar to the normative data. No significant differences were seen in GLP-1, glicentin, glucose, amino acids, or NEFAs. (4) Conclusions: Low fasting concentrations of glucagon are present in patients with VLCAD and cannot be explained by altered stimuli in plasma.
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Affiliation(s)
- Rasmus Stenlid
- Department of Medical Cell Biology, Uppsala University, SE75123 Uppsala, Sweden
| | - Hannes Manell
- Department of Women's and Children's Health, Uppsala University, SE75185 Uppsala, Sweden
| | - Rikard Seth
- Department of Medical Cell Biology, Uppsala University, SE75123 Uppsala, Sweden
| | - Sara Y Cerenius
- Department of Medical Cell Biology, Uppsala University, SE75123 Uppsala, Sweden
| | - Azazul Chowdhury
- Department of Medical Cell Biology, Uppsala University, SE75123 Uppsala, Sweden
| | - Camilla Roa Cortés
- Department of Medical Cell Biology, Uppsala University, SE75123 Uppsala, Sweden
| | - Isabelle Nyqvist
- Department of Medical Cell Biology, Uppsala University, SE75123 Uppsala, Sweden
| | - Thomas Lundqvist
- Department of Women's and Children's Health, Karolinska Institute, SE17177 Stockholm, Sweden
| | - Maria Halldin
- Department of Women's and Children's Health, Karolinska Institute, SE17177 Stockholm, Sweden
| | - Peter Bergsten
- Department of Medical Cell Biology, Uppsala University, SE75123 Uppsala, Sweden
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9
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Hamilton A, Eliasson L, Knudsen JG. Amino acids and the changing face of the α-cell. Peptides 2023:171039. [PMID: 37295651 DOI: 10.1016/j.peptides.2023.171039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 05/31/2023] [Accepted: 06/05/2023] [Indexed: 06/12/2023]
Abstract
Glucagon has long been defined by its glucogenic action and as a result α-cells have been characterised based largely on their interaction with glucose. Recent findings have challenged this preconception, bringing to the fore the significant role glucagon plays in amino acid breakdown and underlining the importance of amino acids in glucagon secretion. The challenge that remains is defining the mechanism that underlie these effects - understanding which amino acids are most important, how they act on the α-cell and how their actions integrate with other fuels such as glucose and fatty acids. This review will describe the current relationship between amino acids and glucagon and how we can use this knowledge to redefine the α-cell.
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Affiliation(s)
- Alexander Hamilton
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Denmark; Department of Clinical Sciences in Malmö, Islet Cell Exocytosis, Lund University Diabetes Centre, Lund University, Malmö, Sweden.
| | - Lena Eliasson
- Department of Clinical Sciences in Malmö, Islet Cell Exocytosis, Lund University Diabetes Centre, Lund University, Malmö, Sweden.
| | - Jakob G Knudsen
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Denmark.
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Mannino GC, Mancuso E, Sbrignadello S, Morettini M, Andreozzi F, Tura A. Chemical Compounds and Ambient Factors Affecting Pancreatic Alpha-Cells Mass and Function: What Evidence? INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:16489. [PMID: 36554367 PMCID: PMC9778390 DOI: 10.3390/ijerph192416489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 12/02/2022] [Accepted: 12/04/2022] [Indexed: 06/17/2023]
Abstract
The exposure to different substances present in the environment can affect the ability of the human body to maintain glucose homeostasis. Some review studies summarized the current evidence about the relationships between environment and insulin resistance or beta-cell dysfunction. Instead, no reviews focused on the relationships between the environment and the alpha cell, although in recent years clear indications have emerged for the pivotal role of the alpha cell in glucose regulation. Thus, the aim of this review was to analyze the studies about the effects of chemical, biological, and physical environmental factors on the alpha cell. Notably, we found studies focusing on the effects of different categories of compounds, including air pollutants, compounds of known toxicity present in common objects, pharmacological agents, and compounds possibly present in food, plus studies on the effects of physical factors (mainly heat exposure). However, the overall number of relevant studies was limited, especially when compared to studies related to the environment and insulin sensitivity or beta-cell function. In our opinion, this was likely due to the underestimation of the alpha-cell role in glucose homeostasis, but since such a role has recently emerged with increasing strength, we expect several new studies about the environment and alpha-cell in the near future.
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Affiliation(s)
- Gaia Chiara Mannino
- Department of Medical and Surgical Sciences, Magna Graecia University of Catanzaro, 88100 Catanzaro, Italy
| | - Elettra Mancuso
- Department of Medical and Surgical Sciences, Magna Graecia University of Catanzaro, 88100 Catanzaro, Italy
| | | | - Micaela Morettini
- Department of Information Engineering, Università Politecnica delle Marche, 60131 Ancona, Italy
| | - Francesco Andreozzi
- Department of Medical and Surgical Sciences, Magna Graecia University of Catanzaro, 88100 Catanzaro, Italy
| | - Andrea Tura
- CNR Institute of Neuroscience, 35127 Padova, Italy
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11
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Capozzi ME, D'Alessio DA, Campbell JE. The past, present, and future physiology and pharmacology of glucagon. Cell Metab 2022; 34:1654-1674. [PMID: 36323234 PMCID: PMC9641554 DOI: 10.1016/j.cmet.2022.10.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 08/23/2022] [Accepted: 09/30/2022] [Indexed: 11/07/2022]
Abstract
The evolution of glucagon has seen the transition from an impurity in the preparation of insulin to the development of glucagon receptor agonists for use in type 1 diabetes. In type 2 diabetes, glucagon receptor antagonists have been explored to reduce glycemia thought to be induced by hyperglucagonemia. However, the catabolic actions of glucagon are currently being leveraged to target the rise in obesity that paralleled that of diabetes, bringing the pharmacology of glucagon full circle. During this evolution, the physiological importance of glucagon advanced beyond the control of hepatic glucose production, incorporating critical roles for glucagon to regulate both lipid and amino acid metabolism. Thus, it is unsurprising that the study of glucagon has left several paradoxes that make it difficult to distill this hormone down to a simplified action. Here, we describe the history of glucagon from the past to the present and suggest some direction to the future of this field.
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Affiliation(s)
- Megan E Capozzi
- Duke Molecular Physiology Institute, Duke University Medical Center, Durham, NC 27701, USA
| | - David A D'Alessio
- Duke Molecular Physiology Institute, Duke University Medical Center, Durham, NC 27701, USA; Department of Medicine, Endocrinology Division, Duke University Medical Center, Durham, NC 27701, USA
| | - Jonathan E Campbell
- Duke Molecular Physiology Institute, Duke University Medical Center, Durham, NC 27701, USA; Department of Medicine, Endocrinology Division, Duke University Medical Center, Durham, NC 27701, USA; Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27701, USA.
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12
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Lipotoxicity in a Vicious Cycle of Pancreatic Beta Cell Exhaustion. Biomedicines 2022; 10:biomedicines10071627. [PMID: 35884932 PMCID: PMC9313354 DOI: 10.3390/biomedicines10071627] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 07/05/2022] [Accepted: 07/05/2022] [Indexed: 02/07/2023] Open
Abstract
Hyperlipidemia is a common metabolic disorder in modern society and may precede hyperglycemia and diabetes by several years. Exactly how disorders of lipid and glucose metabolism are related is still a mystery in many respects. We analyze the effects of hyperlipidemia, particularly free fatty acids, on pancreatic beta cells and insulin secretion. We have developed a computational model to quantitatively estimate the effects of specific metabolic pathways on insulin secretion and to assess the effects of short- and long-term exposure of beta cells to elevated concentrations of free fatty acids. We show that the major trigger for insulin secretion is the anaplerotic pathway via the phosphoenolpyruvate cycle, which is affected by free fatty acids via uncoupling protein 2 and proton leak and is particularly destructive in long-term chronic exposure to free fatty acids, leading to increased insulin secretion at low blood glucose and inadequate insulin secretion at high blood glucose. This results in beta cells remaining highly active in the “resting” state at low glucose and being unable to respond to anaplerotic signals at high pyruvate levels, as is the case with high blood glucose. The observed fatty-acid-induced disruption of anaplerotic pathways makes sense in the context of the physiological role of insulin as one of the major anabolic hormones.
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13
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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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14
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Zhao YF. Free fatty acid receptors in the endocrine regulation of glucose metabolism: Insight from gastrointestinal-pancreatic-adipose interactions. Front Endocrinol (Lausanne) 2022; 13:956277. [PMID: 36246919 PMCID: PMC9554507 DOI: 10.3389/fendo.2022.956277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 09/14/2022] [Indexed: 11/25/2022] Open
Abstract
Glucose metabolism is primarily controlled by pancreatic hormones, with the coordinated assistance of the hormones from gastrointestine and adipose tissue. Studies have unfolded a sophisticated hormonal gastrointestinal-pancreatic-adipose interaction network, which essentially maintains glucose homeostasis in response to the changes in substrates and nutrients. Free fatty acids (FFAs) are the important substrates that are involved in glucose metabolism. FFAs are able to activate the G-protein coupled membrane receptors including GPR40, GPR120, GPR41 and GPR43, which are specifically expressed in pancreatic islet cells, enteroendocrine cells as well as adipocytes. The activation of FFA receptors regulates the secretion of hormones from pancreas, gastrointestine and adipose tissue to influence glucose metabolism. This review presents the effects of the FFA receptors on glucose metabolism via the hormonal gastrointestinal-pancreatic-adipose interactions and the underlying intracellular mechanisms. Furthermore, the development of therapeutic drugs targeting FFA receptors for the treatment of abnormal glucose metabolism such as type 2 diabetes mellitus is summarized.
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15
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Abstract
This review focuses on the human pancreatic islet-including its structure, cell composition, development, function, and dysfunction. After providing a historical timeline of key discoveries about human islets over the past century, we describe new research approaches and technologies that are being used to study human islets and how these are providing insight into human islet physiology and pathophysiology. We also describe changes or adaptations in human islets in response to physiologic challenges such as pregnancy, aging, and insulin resistance and discuss islet changes in human diabetes of many forms. We outline current and future interventions being developed to protect, restore, or replace human islets. The review also highlights unresolved questions about human islets and proposes areas where additional research on human islets is needed.
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Affiliation(s)
- John T Walker
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Diane C Saunders
- Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Marcela Brissova
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Alvin C Powers
- Department 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
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16
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Wang H, Cao J, Su JB, Wang XQ, Wang X, Zhang DM, Wang XH. Serum fatty acid-binding protein 4 levels and responses of pancreatic islet β-cells and α-cells in patients with type 2 diabetes. Diabetol Metab Syndr 2021; 13:70. [PMID: 34174950 PMCID: PMC8234651 DOI: 10.1186/s13098-021-00690-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 06/11/2021] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Serum fatty acid-binding protein 4 (FABP4), as an intracellular lipid chaperone and adipokine, was reported to be related to the incidence of type 2 diabetes (T2D) and diabetic complications, but its association with pancreatic islet β-cell and α-cell functions has not been fully elucidated. So the present study was to investigate the serum FABP4 levels and responses of islet β-cells and α-cells in patients with T2D. METHODS 115 patients with T2D and 89 healthy controls (HC), who received serum FABP4 levels test, were recruited to participate in this study. Moreover, 75-g oral glucose tolerance test (OGTT) was performed in T2D patients to evaluate islet β-cell and α-cell functions. Systemic insulin sensitivity and overall insulin secretion of islet β-cell function were assessed by Matsuda index using C peptide (ISIM-cp) and ratio of the area under the C peptide curve to the glucose curve (AUCcp/glu) during OGTT, respectively. Fasting glucagon (Gluca0min) and postchallenge glucagon assessed by the area under the glucagon curve (AUCgluca) were determined during OGTT to evaluate islet α-cell function. And other various clinical variables were also measured in all participants. Skewed variables were natural log-transformed (ln), such as lnFABP4. RESULTS The serum FABP4 levels in T2D patients were significantly higher than those in HC (p < 0.05). And after partially adjusting for fasting plasma glucose, serum lnFABP4 levels were negatively correlated with lnISIM-cp (r = - 0.332, p < 0.001) and positively correlated with lnAUCcp/glu (r = 0.324, p < 0.001), lnGluca0min (r = 0.200, p = 0.040) and lnAUCgluca (r = 0.311, p < 0.001), respectively, in patients with T2D. Furthermore, when multiple linear regression analyses were applied to adjust for other various clinical variables, serum lnFABP4 levels were found to remain associated with lnISIM-cp (β = - 0.296, t = - 2.900, p = 0.005), lnAUCcp/glu (β = 0.223, t = 2.038, p = 0.046), lnGluca0min (β = 0.272, t = 2.330, p = 0.024) and lnAUCgluca (β = 0.341, t = 3.065, p = 0.004), respectively. CONCLUSION Increased serum FABP4 levels were closely associated with blunted insulin sensitivity, increased insulin secretion, and elevated fasting and postchallenge glucagon levels in patients with T2D.
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Affiliation(s)
- Hong Wang
- Department of Endocrinology, Affiliated Hospital 2 of Nantong University, and First People’s Hospital of Nantong City, No. 6, Haierxiang North Road, Nantong, 226001 China
| | - Jie Cao
- Department of Endocrinology, Affiliated Hospital 2 of Nantong University, and First People’s Hospital of Nantong City, No. 6, Haierxiang North Road, Nantong, 226001 China
| | - Jian-bin Su
- Department of Endocrinology, Affiliated Hospital 2 of Nantong University, and First People’s Hospital of Nantong City, No. 6, Haierxiang North Road, Nantong, 226001 China
| | - Xue-qin Wang
- Department of Endocrinology, Affiliated Hospital 2 of Nantong University, and First People’s Hospital of Nantong City, No. 6, Haierxiang North Road, Nantong, 226001 China
| | - Xing Wang
- Department of Endocrinology, Affiliated Hospital 2 of Nantong University, and First People’s Hospital of Nantong City, No. 6, Haierxiang North Road, Nantong, 226001 China
| | - Dong-mei Zhang
- Medical Research Center, Affiliated Hospital 2 of Nantong University, and First People’s Hospital of Nantong City, No. 6, Haierxiang North Road, Nantong, 226001 China
| | - Xiao-hua Wang
- Department of Endocrinology, Affiliated Hospital 2 of Nantong University, and First People’s Hospital of Nantong City, No. 6, Haierxiang North Road, Nantong, 226001 China
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17
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Mishra A, Liu S, Promes J, Harata M, Sivitz W, Fink B, Bhardwaj G, O'Neill BT, Kang C, Sah R, Strack S, Stephens S, King T, Jackson L, Greenberg AS, Anokye-Danso F, Ahima RS, Ankrum J, Imai Y. Perilipin 2 downregulation in β cells impairs insulin secretion under nutritional stress and damages mitochondria. JCI Insight 2021; 6:144341. [PMID: 33784258 PMCID: PMC8262280 DOI: 10.1172/jci.insight.144341] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 03/24/2021] [Indexed: 12/15/2022] Open
Abstract
Perilipin 2 (PLIN2) is a lipid droplet (LD) protein in β cells that increases under nutritional stress. Downregulation of PLIN2 is often sufficient to reduce LD accumulation. To determine whether PLIN2 positively or negatively affects β cell function under nutritional stress, PLIN2 was downregulated in mouse β cells, INS1 cells, and human islet cells. β Cell–specific deletion of PLIN2 in mice on a high-fat diet reduced glucose-stimulated insulin secretion (GSIS) in vivo and in vitro. Downregulation of PLIN2 in INS1 cells blunted GSIS after 24-hour incubation with 0.2 mM palmitic acid. Downregulation of PLIN2 in human pseudoislets cultured at 5.6 mM glucose impaired both phases of GSIS, indicating that PLIN2 is critical for GSIS. Downregulation of PLIN2 decreased specific OXPHOS proteins in all 3 models and reduced oxygen consumption rates in INS1 cells and mouse islets. Moreover, we found that PLIN2-deficient INS1 cells increased the distribution of a fluorescent oleic acid analog to mitochondria and showed signs of mitochondrial stress, as indicated by susceptibility to fragmentation and alterations of acyl-carnitines and glucose metabolites. Collectively, PLIN2 in β cells has an important role in preserving insulin secretion, β cell metabolism, and mitochondrial function under nutritional stress.
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Affiliation(s)
- Akansha Mishra
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.,Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa, USA
| | - Siming Liu
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.,Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa, USA
| | - Joseph Promes
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.,Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa, USA
| | - Mikako Harata
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.,Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa, USA
| | - William Sivitz
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.,Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa, USA.,Iowa City Veterans Affairs Medical Center, Iowa City, Iowa, USA
| | - Brian Fink
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.,Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa, USA.,Iowa City Veterans Affairs Medical Center, Iowa City, Iowa, USA
| | - Gourav Bhardwaj
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.,Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa, USA
| | - Brian T O'Neill
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.,Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa, USA.,Iowa City Veterans Affairs Medical Center, Iowa City, Iowa, USA
| | - Chen Kang
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Rajan Sah
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Stefan Strack
- Department of Neuroscience and Pharmacology, Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa, USA
| | - Samuel Stephens
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.,Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa, USA
| | - Timothy King
- Department of Internal Medicine, Eastern Virginia Medical School, Norfolk, Virginia, USA
| | - Laura Jackson
- Department of Internal Medicine, Eastern Virginia Medical School, Norfolk, Virginia, USA
| | - Andrew S Greenberg
- Obesity and Metabolism Laboratory, Jean Mayer United States Department of Agriculture Human Nutrition Research Center on Aging at Tufts University, Boston, Massachusetts, USA
| | | | - Rexford S Ahima
- Department of Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland, USA
| | - James Ankrum
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa, USA.,Roy J. Carver Department of Biomedical Engineering, University of Iowa, Iowa City, Iowa, USA
| | - Yumi Imai
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.,Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa, USA
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18
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Chen X, Maldonado E, DeFronzo RA, Tripathy D. Impaired Suppression of Glucagon in Obese Subjects Parallels Decline in Insulin Sensitivity and Beta-Cell Function. J Clin Endocrinol Metab 2021; 106:1398-1409. [PMID: 33524152 PMCID: PMC8063259 DOI: 10.1210/clinem/dgab019] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Indexed: 12/23/2022]
Abstract
AIM To examine the relationship between plasma glucagon levels and insulin sensitivity and insulin secretion in obese subjects. METHODS Suppression of plasma glucagon was examined in 275 obese Hispanic Americans with varying glucose tolerance. All subjects received a 2-hour oral glucose tolerance test (OGTT) and a subset (n = 90) had euglycemic hyperinsulinemic clamp. During OGTT, we quantitated suppression of plasma glucagon concentration, Matsuda index of insulin sensitivity, and insulin secretion/insulin resistance (disposition) index. Plasma glucagon suppression was compared between quartiles of insulin sensitivity and beta-cell function. RESULTS Fasting plasma glucagon levels were similar in obese subjects with normal glucose tolerance (NGT), prediabetes, and type 2 diabetes (T2D), but the fasting glucagon/insulin ratio decreased progressively from NGT to prediabetes to T2D (9.28 ± 0.66 vs 6.84 ± 0.44 vs 5.84 ± 0.43; P < 0.001). Fasting and 2-hour plasma glucagon levels during OGTT progressively increased and correlated positively with severity of insulin resistance (both Matsuda index and euglycemic hyperinsulinemic clamp). The fasting glucagon/insulin ratio declined with worsening insulin sensitivity and beta-cell function, and correlated with whole-body insulin sensitivity (Matsuda index, r = 0.81; P < 0.001) and beta-cell function (r = 0.35; P < 0.001). The glucagon/insulin ratio also correlated and with beta-cell function during OGTT at 60 and 120 minutes (r = -0.47; P < 0.001 and r = -0.32; P < 0.001). CONCLUSION Insulin-mediated suppression of glucagon secretion in obese subjects is impaired with increasing severity of glucose intolerance and parallels the severity of insulin resistance and beta-cell dysfunction.
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Affiliation(s)
- Xi Chen
- Department of Medicine, Diabetes Division, University of Texas Health Science Center, San Antonio, TX, USA
| | - Enrique Maldonado
- Department of Medicine, Diabetes Division, University of Texas Health Science Center, San Antonio, TX, USA
| | - Ralph A DeFronzo
- Department of Medicine, Diabetes Division, University of Texas Health Science Center, San Antonio, TX, USA
- Audie L Murphy VA Hospital, South Texas Veterans Health Care System, San Antonio, TX, USA
| | - Devjit Tripathy
- Department of Medicine, Diabetes Division, University of Texas Health Science Center, San Antonio, TX, USA
- Audie L Murphy VA Hospital, South Texas Veterans Health Care System, San Antonio, TX, USA
- Correspondence: Devjit Tripathy, MD, PhD, Division of Diabetes, University of Texas Health Science Center, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA.
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19
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Role of cAMP in Double Switch of Glucagon Secretion. Cells 2021; 10:cells10040896. [PMID: 33919776 PMCID: PMC8070687 DOI: 10.3390/cells10040896] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 04/12/2021] [Accepted: 04/12/2021] [Indexed: 01/03/2023] Open
Abstract
Glucose metabolism plays a crucial role in modulating glucagon secretion in pancreatic alpha cells. However, the downstream effects of glucose metabolism and the activated signaling pathways influencing glucagon granule exocytosis are still obscure. We developed a computational alpha cell model, implementing metabolic pathways of glucose and free fatty acids (FFA) catabolism and an intrinsically activated cAMP signaling pathway. According to the model predictions, increased catabolic activity is able to suppress the cAMP signaling pathway, reducing exocytosis in a Ca2+-dependent and Ca2+ independent manner. The effect is synergistic to the pathway involving ATP-dependent closure of KATP channels and consequent reduction of Ca2+. We analyze the contribution of each pathway to glucagon secretion and show that both play decisive roles, providing a kind of "secure double switch". The cAMP-driven signaling switch plays a dominant role, while the ATP-driven metabolic switch is less favored. The ratio is approximately 60:40, according to the most recent experimental evidence.
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20
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Lou PH, Lucchinetti E, Wawrzyniak P, Morsy Y, Wawrzyniak M, Scharl M, Krämer SD, Rogler G, Hersberger M, Zaugg M. Choice of Lipid Emulsion Determines Inflammation of the Gut-Liver Axis, Incretin Profile, and Insulin Signaling in a Murine Model of Total Parenteral Nutrition. Mol Nutr Food Res 2021; 65:e2000412. [PMID: 32729969 DOI: 10.1002/mnfr.202000412] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 07/16/2020] [Indexed: 12/19/2022]
Abstract
SCOPE The aim of this study is to test whether the choice of the lipid emulsion in total parenteral nutrition (TPN), that is, n-3 fatty acid-based Omegaven versus n-6 fatty acid-based Intralipid, determines inflammation in the liver, the incretin profile, and insulin resistance. METHODS AND RESULTS Jugular vein catheters (JVC) are placed in C57BL/6 mice and used for TPN for 7 days. Mice are randomized into a saline group (saline infusion with oral chow), an Intralipid group (IL-TPN, no chow), an Omegaven group (OV-TPN, no chow), or a chow only group (without JVC). Both TPN elicite higher abundance of lipopolysaccharide binding protein in the liver, but only IL-TPN increases interleukin-6 and interferon-γ, while OV-TPN reduces interleukin-4, monocyte chemoattractant protein-1, and interleukin-1α. Insulin plasma concentrations are higher in both TPN, while glucagon and glucagon-like peptide-1 (GLP-1) were higher in IL-TPN. Gluconeogenesis is increased in IL-TPN and the nuclear profile of key metabolic transcription factors shows a liver-protective phenotype in OV-TPN. OV-TPN increases insulin sensitivity in the liver and skeletal muscle. CONCLUSION OV-TPN as opposed to IL-TPN mitigates inflammation in the liver and reduces the negative metabolic effects of hyperinsulinemia and hyperglucagonemia by "re-sensitizing" the liver and skeletal muscle to insulin.
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Affiliation(s)
- Phing-How Lou
- Department of Pharmacology, University of Alberta, Edmonton, T6G 2R3, Canada
| | - Eliana Lucchinetti
- Department of Anesthesiology and Pain Medicine and Cardiovascular Research Centre, University of Alberta, Edmonton, T6G 2R3, Canada
| | - Paulina Wawrzyniak
- Division of Clinical Chemistry and Biochemistry, University Children's Hospital Zurich, Zurich, 8032, Switzerland
| | - Yasser Morsy
- Department of Gastroenterology and Hepatology, University Hospital Zurich and University of Zurich, Zurich, 8091, Switzerland
| | - Marcin Wawrzyniak
- Department of Gastroenterology and Hepatology, University Hospital Zurich and University of Zurich, Zurich, 8091, Switzerland
| | - Michael Scharl
- Department of Gastroenterology and Hepatology, University Hospital Zurich and University of Zurich, Zurich, 8091, Switzerland
| | - Stefanie D Krämer
- Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, 8093, Switzerland
| | - Gerhard Rogler
- Department of Gastroenterology and Hepatology, University Hospital Zurich and University of Zurich, Zurich, 8091, Switzerland
| | - Martin Hersberger
- Division of Clinical Chemistry and Biochemistry, University Children's Hospital Zurich, Zurich, 8032, Switzerland
- Center for Integrative Human Physiology, University of Zurich, Zurich, 8057, Switzerland
| | - Michael Zaugg
- Department of Pharmacology, University of Alberta, Edmonton, T6G 2R3, Canada
- Department of Anesthesiology and Pain Medicine and Cardiovascular Research Centre, University of Alberta, Edmonton, T6G 2R3, Canada
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21
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Lipotoxic Impairment of Mitochondrial Function in β-Cells: A Review. Antioxidants (Basel) 2021; 10:antiox10020293. [PMID: 33672062 PMCID: PMC7919463 DOI: 10.3390/antiox10020293] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 02/06/2021] [Accepted: 02/11/2021] [Indexed: 02/08/2023] Open
Abstract
Lipotoxicity is a major contributor to type 2 diabetes mainly promoting mitochondrial dysfunction. Lipotoxic stress is mediated by elevated levels of free fatty acids through various mechanisms and pathways. Impaired peroxisome proliferator-activated receptor (PPAR) signaling, enhanced oxidative stress levels, and uncoupling of the respiratory chain result in ATP deficiency, while β-cell viability can be severely impaired by lipotoxic modulation of PI3K/Akt and mitogen-activated protein kinase (MAPK)/extracellular-signal-regulated kinase (ERK) pathways. However, fatty acids are physiologically required for an unimpaired β-cell function. Thus, preparation, concentration, and treatment duration determine whether the outcome is beneficial or detrimental when fatty acids are employed in experimental setups. Further, ageing is a crucial contributor to β-cell decay. Cellular senescence is connected to loss of function in β-cells and can further be promoted by lipotoxicity. The potential benefit of nutrients has been broadly investigated, and particularly polyphenols were shown to be protective against both lipotoxicity and cellular senescence, maintaining the physiology of β-cells. Positive effects on blood glucose regulation, mitigation of oxidative stress by radical scavenging properties or regulation of antioxidative enzymes, and modulation of apoptotic factors were reported. This review summarizes the significance of lipotoxicity and cellular senescence for mitochondrial dysfunction in the pancreatic β-cell and outlines potential beneficial effects of plant-based nutrients by the example of polyphenols.
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Henquin JC. Paracrine and autocrine control of insulin secretion in human islets: evidence and pending questions. Am J Physiol Endocrinol Metab 2021; 320:E78-E86. [PMID: 33103455 DOI: 10.1152/ajpendo.00485.2020] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Insulin secretion by β-cells is largely controlled by circulating nutrients, hormones, and neurotransmitters. However, recent years have witnessed the multiplication of studies investigating whether local regulation also takes place within pancreatic islets, in which β-cells cohabit with several other cell types. The cell composition and architectural organization of human islets differ from those of rodent islets and are particularly favorable to cellular interactions. An impressive number of hormonal (glucagon, glucagon-like peptide-1, somatostatin, etc.) and nonhormonal products (ATP, acetylcholine, γ-aminobutyric acid, dopamine, etc.) are released by islet cells and have been implicated in a local control of insulin secretion. This review analyzes reports directly testing paracrine and autocrine control of insulin secretion in isolated human islets. Many of these studies were designed on background information collected in rodent islets. However, the perspective of the review is not to highlight species similarities or specificities but to contrast established and speculative mechanisms in human islets. It will be shown that the current evidence is convincing only for a minority of candidates for a paracrine function whereas arguments supporting a physiological role of others do not stand up to scrutiny. Several pending questions await further investigation.
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Affiliation(s)
- Jean-Claude Henquin
- Unit of Endocrinology and Metabolism, Faculty of Medicine, University of Louvain, Brussels, Belgium
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Guo H, Ma C, Wu X, Pan C. Functional Status of Pancreatic α and β Cells in Type 2 Diabetes Mellitus Patients with Different Plasma Triglyceride Levels: A Retrospective Analysis. Int J Endocrinol 2021; 2021:9976067. [PMID: 34457002 PMCID: PMC8387189 DOI: 10.1155/2021/9976067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 07/19/2021] [Accepted: 07/31/2021] [Indexed: 11/25/2022] Open
Abstract
OBJECTIVE To investigate the functional status of pancreatic α and β cells in Type 2 diabetes mellitus (T2DM) patients with different plasma triglyceride (TG) levels. TG levels can be prognostic markers for T2DM. METHODS A total of 328 patients with T2DM were divided into three groups according to different TG levels: the TGL group: TG < 1.7 mmol/L; TGM group: 1.7 mmol/L ≤ TG < 2.3 mmol/L; and TGH group: TG ≥ 2.3 mmol/L. An oral glucose tolerance test (OGTT), insulin release test, and glucagon release test were performed in each patient. The changes of glucagon, glucagon/insulin ratio, early insulin secretion index (ΔI 30/ΔG 30), and area under the insulin curve (AUCI) were compared among each group. Also, the correlations between glucagon and pancreatic β-cell function, glycosylated hemoglobin (HbA1c), and other indices were analyzed. RESULTS With the increase of TG, the fasting and postprandial glucagon levels, the glucagon/insulin ratio, and the area under the glucagon curve (AUCG) presented an increasing trend. The homeostasis model assessment of insulin resistance (HOMA-IR) of the TGH group was significantly increased compared to the TGL and TGM groups. In addition to the increase in TG levels, the insulin sensitivity index (ISI), homeostasis model assessment for β-cell function index (HOMA-β), ΔI 30/ΔG 30, and AUCI displayed a reducing trend. Glucagon was negatively correlated with ΔI 30/ΔG 30, high-density lipoprotein (HDL), HOMA-β, body mass index (BMI), ISI, and AUCI (P < 0.05) and positively correlated with fasting blood glucose (FPG), AUCG, HOMA-IR, HbA1c, duration, TG, low-density lipoprotein (LDL), and total cholesterol (TC) (P < 0.05). CONCLUSION Hypertriglyceridemia aggravated the dysfunction of pancreatic α and β cells. A reasonable control of the TG level makes it easier for blood glucose to reach the standard.
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Affiliation(s)
- Hang Guo
- NHC Key Laboratory of Hormones and Development, Tianjin Key Laboratory of Metabolic Diseases, Chu Hsien-I Memorial Hospital & Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin, China
| | - Chunlei Ma
- Department of Urology, Tianjin 4th Center Hospital, The Fourth Central Hospital Affiliated to Nankai University, Tianjin 300140, China
| | - Xiaoming Wu
- NHC Key Laboratory of Hormones and Development, Tianjin Key Laboratory of Metabolic Diseases, Chu Hsien-I Memorial Hospital & Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin, China
| | - Congqing Pan
- NHC Key Laboratory of Hormones and Development, Tianjin Key Laboratory of Metabolic Diseases, Chu Hsien-I Memorial Hospital & Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin, China
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McNally LA, Altamimi TR, Fulghum K, Hill BG. Considerations for using isolated cell systems to understand cardiac metabolism and biology. J Mol Cell Cardiol 2020; 153:26-41. [PMID: 33359038 DOI: 10.1016/j.yjmcc.2020.12.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 12/13/2020] [Accepted: 12/16/2020] [Indexed: 12/11/2022]
Abstract
Changes in myocardial metabolic activity are fundamentally linked to cardiac health and remodeling. Primary cardiomyocytes, induced pluripotent stem cell-derived cardiomyocytes, and transformed cardiomyocyte cell lines are common models used to understand how (patho)physiological conditions or stimuli contribute to changes in cardiac metabolism. These cell models are helpful also for defining metabolic mechanisms of cardiac dysfunction and remodeling. Although technical advances have improved our capacity to measure cardiomyocyte metabolism, there is often heterogeneity in metabolic assay protocols and cell models, which could hinder data interpretation and discernment of the mechanisms of cardiac (patho)physiology. In this review, we discuss considerations for integrating cardiomyocyte cell models with techniques that have become relatively common in the field, such as respirometry and extracellular flux analysis. Furthermore, we provide overviews of metabolic assays that complement XF analyses and that provide information on not only catabolic pathway activity, but biosynthetic pathway activity and redox status as well. Cultivating a more widespread understanding of the advantages and limitations of metabolic measurements in cardiomyocyte cell models will continue to be essential for the development of coherent metabolic mechanisms of cardiac health and pathophysiology.
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Affiliation(s)
- Lindsey A McNally
- Department of Medicine, Division of Environmental Medicine, Christina Lee Brown Envirome Institute, Diabetes and Obesity Center, University of Louisville, Louisville, KY, USA
| | - Tariq R Altamimi
- Department of Medicine, Division of Environmental Medicine, Christina Lee Brown Envirome Institute, Diabetes and Obesity Center, University of Louisville, Louisville, KY, USA
| | - Kyle Fulghum
- Department of Medicine, Division of Environmental Medicine, Christina Lee Brown Envirome Institute, Diabetes and Obesity Center, University of Louisville, Louisville, KY, USA
| | - Bradford G Hill
- Department of Medicine, Division of Environmental Medicine, Christina Lee Brown Envirome Institute, Diabetes and Obesity Center, University of Louisville, Louisville, KY, USA.
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Mechanisms of the Regulation and Dysregulation of Glucagon Secretion. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2020; 2020:3089139. [PMID: 32774668 PMCID: PMC7396046 DOI: 10.1155/2020/3089139] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 07/11/2020] [Indexed: 02/06/2023]
Abstract
Glucagon, a hormone secreted by pancreatic alpha cells, contributes to the maintenance of normal blood glucose concentration by inducing hepatic glucose production in response to declining blood glucose. However, glucagon hypersecretion contributes to the pathogenesis of type 2 diabetes. Moreover, diabetes is associated with relative glucagon undersecretion at low blood glucose and oversecretion at normal and high blood glucose. The mechanisms of such alpha cell dysfunctions are not well understood. This article reviews the genesis of alpha cell dysfunctions during the pathogenesis of type 2 diabetes and after the onset of type 1 and type 2 diabetes. It unravels a signaling pathway that contributes to glucose- or hydrogen peroxide-induced glucagon secretion, whose overstimulation contributes to glucagon dysregulation, partly through oxidative stress and reduced ATP synthesis. The signaling pathway involves phosphatidylinositol-3-kinase, protein kinase B, protein kinase C delta, non-receptor tyrosine kinase Src, and phospholipase C gamma-1. This knowledge will be useful in the design of new antidiabetic agents or regimens.
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Reduced somatostatin signalling leads to hypersecretion of glucagon in mice fed a high-fat diet. Mol Metab 2020; 40:101021. [PMID: 32446876 PMCID: PMC7322681 DOI: 10.1016/j.molmet.2020.101021] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 05/11/2020] [Accepted: 05/14/2020] [Indexed: 11/29/2022] Open
Abstract
Objectives Elevated plasma glucagon is an early symptom of diabetes, occurring in subjects with impaired glucose regulation. Here, we explored alpha-cell function in female mice fed a high-fat diet (HFD). Methods Female mice expressing the Ca2+ indicator GCaMP3 specifically in alpha-cells were fed a high-fat or control (CTL) diet. We then conducted in vivo phenotyping of these mice, as well as experiments on isolated (ex vivo) islets and in the in situ perfused pancreas. Results In HFD-fed mice, fed plasma glucagon levels were increased and glucagon secretion from isolated islets and in the perfused mouse pancreas was also elevated. In mice fed a CTL diet, increasing glucose reduced intracellular Ca2+ ([Ca2+]i) oscillation frequency and amplitude. This effect was also observed in HFD mice; however, both the frequency and amplitude of the [Ca2+]i oscillations were higher than those in CTL alpha-cells. Given that alpha-cells are under strong paracrine control from neighbouring somatostatin-secreting delta-cells, we hypothesised that this elevation of alpha-cell output was due to a lack of somatostatin (SST) secretion. Indeed, SST secretion in isolated islets from HFD-fed mice was reduced but exogenous SST also failed to suppress glucagon secretion and [Ca2+]i activity from HFD alpha-cells, in contrast to observations in CTL mice. Conclusions These findings suggest that reduced delta-cell function, combined with intrinsic changes in alpha-cells including sensitivity to somatostatin, accounts for the hyperglucagonaemia in mice fed a HFD. HFD feeding causes hyperglucagonaemia in vivo. Glucagon is inadequately suppressed by glucose in HFD-fed mice. Alpha-cell [Ca2+]i oscillations and glucagon output are elevated ex vivo in response to HFD feeding. SST secretion from HFD islets is reduced. Alpha-cells from HFD-fed mice become ‘resistant’ to SST.
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Grubelnik V, Zmazek J, Markovič R, Gosak M, Marhl M. Modelling of energy-driven switch for glucagon and insulin secretion. J Theor Biol 2020; 493:110213. [PMID: 32109481 DOI: 10.1016/j.jtbi.2020.110213] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 02/19/2020] [Accepted: 02/24/2020] [Indexed: 12/14/2022]
Abstract
We present a mathematical model of the energy-driven metabolic switch for glucagon and insulin secretion from pancreatic alpha and beta cells, respectively. The energy status related to hormone secretion is studied for various glucose concentrations. Additionally, the physiological response is studied with regards to the presence of other metabolites, particularly the free-fatty acids. At low glucose, the ATP production in alpha cells is high due to free-fatty acids oxidation in mitochondria, which enables glucagon secretion. When the glucose concentration is elevated above the threshold value, the glucagon secretion is switched off due to the contribution of glycolytic ATP production, representing an "anaerobic switch". On the other hand, during hypoglycemia, the ATP production in beta cells is low, reflecting a "waiting state" for glucose as the main metabolite. When glucose is elevated above the threshold value, the oxidative fate of glucose in mitochondria is the main source of energy required for effective insulin secretion, i.e. the "aerobic switch". Our results show the importance of well-regulated and fine-tuned energetic processes in pancreatic alpha and beta cells required for efficient hormone secretion and hence effective blood glucose regulation. These energetic processes have to be appropriately switched on and off based on the sensing of different metabolites by alpha and beta cells. Our computational results indicate that disturbances in cell energetics (e.g. mitochondrial dysfunction), and dysfunctional metabolite sensing and distribution throughout the cell might be related to pathologies such as metabolic syndrome and diabetes.
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Affiliation(s)
- Vladimir Grubelnik
- Faculty of Electrical Engineering and Computer Science, University of Maribor, Maribor SI-2000, Slovenia
| | - Jan Zmazek
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor SI-2000, Slovenia
| | - Rene Markovič
- Faculty of Electrical Engineering and Computer Science, University of Maribor, Maribor SI-2000, Slovenia; Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor SI-2000, Slovenia
| | - Marko Gosak
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor SI-2000, Slovenia; Faculty of Medicine, University of Maribor, Maribor SI-2000, Slovenia
| | - Marko Marhl
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor SI-2000, Slovenia; Faculty of Medicine, University of Maribor, Maribor SI-2000, Slovenia; Faculty of Education, University of Maribor, Maribor SI-2000, Slovenia.
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Pozuelo-Sanchez I, Villasanta-Gonzalez A, Alcala-Diaz JF, Vals-Delgado C, Leon-Acuña A, Gonzalez-Requero A, Yubero-Serrano EM, Luque RM, Caballero-Villarraso J, Quesada I, Ordovas JM, Pérez-Martinez P, Roncero-Ramos I, Lopez-Miranda J. Postprandial Lipemia Modulates Pancreatic Alpha-Cell Function in the Prediction of Type 2 Diabetes Development: The CORDIOPREV Study. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2020; 68:1266-1275. [PMID: 31937103 DOI: 10.1021/acs.jafc.9b06801] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Diabetes (T2DM) is a major global health issue, and developing new approaches to its prevention is of paramount importance. We hypothesized that abnormalities in lipid metabolism are involved in alpha-cell deregulation. We therefore studied the metabolic factors underlying alpha-cell dysfunction in T2DM progression after a dietary intervention (Mediterranean and low-fat). Additionally, we evaluated whether postprandial glucagon levels may be considered as a predictive factor of T2DM in cardiovascular patients. Non-T2DM participants from the CORDIOPREV study were categorized by tertiles of the area under the curve (AUC) for triacylglycerols and also by tertiles of AUC for glucagon. Our results showed that patients with higher triacylglycerols levels presented elevated postprandial glucagon (P = 0.009). Moreover, we observed higher risk of T2DM (hazard ratio: 2.65; 95% confidence interval: 1.56-4.53) in subjects with elevated glucagon. In conclusion, high postprandial lipemia may induce alpha-cell dysfunction in cardiovascular patients. Our results also showed that postprandial glucagon levels could be used to predict T2DM development.
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Affiliation(s)
- Isabel Pozuelo-Sanchez
- Lipids and Atherosclerosis Unit, Department of Internal Medicine, Maimonides Biomedical Research Institute of Cordoba (IMIBIC), Reina Sofia University Hospital , University of Cordoba , Córdoba 14004 , Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN) , Instituto de Salud Carlos III , Madrid 28029 , Spain
| | - Alejandro Villasanta-Gonzalez
- Lipids and Atherosclerosis Unit, Department of Internal Medicine, Maimonides Biomedical Research Institute of Cordoba (IMIBIC), Reina Sofia University Hospital , University of Cordoba , Córdoba 14004 , Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN) , Instituto de Salud Carlos III , Madrid 28029 , Spain
| | - Juan Francisco Alcala-Diaz
- Lipids and Atherosclerosis Unit, Department of Internal Medicine, Maimonides Biomedical Research Institute of Cordoba (IMIBIC), Reina Sofia University Hospital , University of Cordoba , Córdoba 14004 , Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN) , Instituto de Salud Carlos III , Madrid 28029 , Spain
| | - Cristina Vals-Delgado
- Lipids and Atherosclerosis Unit, Department of Internal Medicine, Maimonides Biomedical Research Institute of Cordoba (IMIBIC), Reina Sofia University Hospital , University of Cordoba , Córdoba 14004 , Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN) , Instituto de Salud Carlos III , Madrid 28029 , Spain
| | - Ana Leon-Acuña
- Lipids and Atherosclerosis Unit, Department of Internal Medicine, Maimonides Biomedical Research Institute of Cordoba (IMIBIC), Reina Sofia University Hospital , University of Cordoba , Córdoba 14004 , Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN) , Instituto de Salud Carlos III , Madrid 28029 , Spain
| | - Anabel Gonzalez-Requero
- Lipids and Atherosclerosis Unit, Department of Internal Medicine, Maimonides Biomedical Research Institute of Cordoba (IMIBIC), Reina Sofia University Hospital , University of Cordoba , Córdoba 14004 , Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN) , Instituto de Salud Carlos III , Madrid 28029 , Spain
| | - Elena Maria Yubero-Serrano
- Lipids and Atherosclerosis Unit, Department of Internal Medicine, Maimonides Biomedical Research Institute of Cordoba (IMIBIC), Reina Sofia University Hospital , University of Cordoba , Córdoba 14004 , Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN) , Instituto de Salud Carlos III , Madrid 28029 , Spain
| | - Raul Miguel Luque
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN) , Instituto de Salud Carlos III , Madrid 28029 , Spain
- Department of Cell Biology, Physiology, and Immunology, Maimonides Biomedical Research Institute of Córdoba (IMIBIC), Reina Sofía University Hospital , University of Córdoba , Córdoba 14004 , Spain
| | | | - Ivan Quesada
- Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDiBE) , Universidad Miguel Hernández and Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM) , Elche 03202 , Spain
| | - José María Ordovas
- Nutrition and Genomics Laboratory , J.M.-US Department of Agriculture Human Nutrition Research Center on Aging at Tufts University , Boston , Massachusetts 02111 , United States
- IMDEA Alimentacion , Madrid 28049 , Spain
| | - Pablo Pérez-Martinez
- Lipids and Atherosclerosis Unit, Department of Internal Medicine, Maimonides Biomedical Research Institute of Cordoba (IMIBIC), Reina Sofia University Hospital , University of Cordoba , Córdoba 14004 , Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN) , Instituto de Salud Carlos III , Madrid 28029 , Spain
| | - Irene Roncero-Ramos
- Lipids and Atherosclerosis Unit, Department of Internal Medicine, Maimonides Biomedical Research Institute of Cordoba (IMIBIC), Reina Sofia University Hospital , University of Cordoba , Córdoba 14004 , Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN) , Instituto de Salud Carlos III , Madrid 28029 , Spain
| | - Jose Lopez-Miranda
- Lipids and Atherosclerosis Unit, Department of Internal Medicine, Maimonides Biomedical Research Institute of Cordoba (IMIBIC), Reina Sofia University Hospital , University of Cordoba , Córdoba 14004 , Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN) , Instituto de Salud Carlos III , Madrid 28029 , Spain
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Taddeo EP, Alsabeeh N, Baghdasarian S, Wikstrom JD, Ritou E, Sereda S, Erion K, Li J, Stiles L, Abdulla M, Swanson Z, Wilhelm JJ, Bellin MD, Kibbey RG, Liesa M, Shirihai OS. Mitochondrial Proton Leak Regulated by Cyclophilin D Elevates Insulin Secretion in Islets at Nonstimulatory Glucose Levels. Diabetes 2020; 69:131-145. [PMID: 31740442 PMCID: PMC6971491 DOI: 10.2337/db19-0379] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 11/11/2019] [Indexed: 12/13/2022]
Abstract
Fasting hyperinsulinemia precedes the development of type 2 diabetes. However, it is unclear whether fasting insulin hypersecretion is a primary driver of insulin resistance or a consequence of the progressive increase in fasting glycemia induced by insulin resistance in the prediabetic state. Herein, we have discovered a mechanism that specifically regulates non-glucose-stimulated insulin secretion (NGSIS) in pancreatic islets that is activated by nonesterified free fatty acids, the major fuel used by β-cells during fasting. We show that the mitochondrial permeability transition pore regulator cyclophilin D (CypD) promotes NGSIS, but not glucose-stimulated insulin secretion, by increasing mitochondrial proton leak. Islets from prediabetic obese mice show significantly higher CypD-dependent proton leak and NGSIS compared with lean mice. Proton leak-mediated NGSIS is conserved in human islets and is stimulated by exposure to nonesterified free fatty acids at concentrations observed in obese subjects. Mechanistically, proton leak activates islet NGSIS independently of mitochondrial ATP synthesis but ultimately requires closure of the KATP channel. In summary, we have described a novel nonesterified free fatty acid-stimulated pathway that selectively drives pancreatic islet NGSIS, which may be therapeutically exploited as an alternative way to halt fasting hyperinsulinemia and the progression of type 2 diabetes.
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Affiliation(s)
- Evan P Taddeo
- Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA
| | - Nour Alsabeeh
- Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA
- Department of Physiology, Faculty of Medicine, Kuwait University, Kuwait City, Kuwait
| | - Siyouneh Baghdasarian
- Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA
| | - Jakob D Wikstrom
- Dermatology and Venereology Unit, Department of Medicine, Karolinska Institutet, and Department of Dermato-Venereology, Karolinska University Hospital, Stockholm, Sweden
| | - Eleni Ritou
- Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA
| | - Samuel Sereda
- Endocrinology, Diabetes, Nutrition and Weight Management Section, Department of Medicine, Boston University School of Medicine, Boston, MA
| | - Karel Erion
- Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA
| | - Jin Li
- Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA
| | - Linsey Stiles
- Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA
| | - Muhamad Abdulla
- Department of Surgery and Schulze Diabetes Institute, University of Minnesota School of Medicine, Minneapolis, MN
| | - Zachary Swanson
- Department of Surgery and Schulze Diabetes Institute, University of Minnesota School of Medicine, Minneapolis, MN
| | - Joshua J Wilhelm
- Department of Surgery and Schulze Diabetes Institute, University of Minnesota School of Medicine, Minneapolis, MN
| | - Melena D Bellin
- Department of Surgery and Schulze Diabetes Institute, University of Minnesota School of Medicine, Minneapolis, MN
- Division of Pediatric Endocrinology, Department of Pediatrics, University of Minnesota Medical School, Minneapolis, MN
| | - Richard G Kibbey
- Departments of Internal Medicine (Endocrinology) and Cellular & Molecular Physiology, Yale University, New Haven, CT
| | - Marc Liesa
- Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA
- Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA
| | - Orian S Shirihai
- Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA
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Wendt A, Eliasson L. Pancreatic α-cells - The unsung heroes in islet function. Semin Cell Dev Biol 2020; 103:41-50. [PMID: 31983511 DOI: 10.1016/j.semcdb.2020.01.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 01/17/2020] [Accepted: 01/20/2020] [Indexed: 01/15/2023]
Abstract
The pancreatic islets of Langerhans consist of several hormone-secreting cell types important for blood glucose control. The insulin secreting β-cells are the best studied of these cell types, but less is known about the glucagon secreting α-cells. The α-cells secrete glucagon as a response to low blood glucose. The major function of glucagon is to release glucose from the glycogen stores in the liver. In both type 1 and type 2 diabetes, glucagon secretion is dysregulated further exaggerating the hyperglycaemia, and in type 1 diabetes α-cells fail to counter regulate hypoglycaemia. Although glucagon has been recognized for almost 100 years, the understanding of how glucagon secretion is regulated and how glucagon act within the islet is far from complete. However, α-cell research has taken off lately which is promising for future knowledge. In this review we aim to highlight α-cell regulation and glucagon secretion with a special focus on recent discoveries from human islets. We will present some novel aspects of glucagon function and effects of selected glucose lowering agents on glucagon secretion.
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Affiliation(s)
- Anna Wendt
- Islet Cell Exocytosis, Lund University Diabetes Centre, Department of Clinical Sciences Malmö, Lund University, Clinical Research Centre, SUS, Malmö, Sweden
| | - Lena Eliasson
- Islet Cell Exocytosis, Lund University Diabetes Centre, Department of Clinical Sciences Malmö, Lund University, Clinical Research Centre, SUS, Malmö, Sweden.
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31
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Gilon P. The Role of α-Cells in Islet Function and Glucose Homeostasis in Health and Type 2 Diabetes. J Mol Biol 2020; 432:1367-1394. [PMID: 31954131 DOI: 10.1016/j.jmb.2020.01.004] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 12/23/2019] [Accepted: 01/06/2020] [Indexed: 01/09/2023]
Abstract
Pancreatic α-cells are the major source of glucagon, a hormone that counteracts the hypoglycemic action of insulin and strongly contributes to the correction of acute hypoglycemia. The mechanisms by which glucose controls glucagon secretion are hotly debated, and it is still unclear to what extent this control results from a direct action of glucose on α-cells or is indirectly mediated by β- and/or δ-cells. Besides its hyperglycemic action, glucagon has many other effects, in particular on lipid and amino acid metabolism. Counterintuitively, glucagon seems also required for an optimal insulin secretion in response to glucose by acting on its cognate receptor and, even more importantly, on GLP-1 receptors. Patients with diabetes mellitus display two main alterations of glucagon secretion: a relative hyperglucagonemia that aggravates hyperglycemia, and an impaired glucagon response to hypoglycemia. Under metabolic stress states, such as diabetes, pancreatic α-cells also secrete GLP-1, a glucose-lowering hormone, whereas the gut can produce glucagon. The contribution of extrapancreatic glucagon to the abnormal glucose homeostasis is unclear. Here, I review the possible mechanisms of control of glucagon secretion and the role of α-cells on islet function in healthy state. I discuss the possible causes of the abnormal glucagonemia in diabetes, with particular emphasis on type 2 diabetes, and I briefly comment the current antidiabetic therapies affecting α-cells.
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Affiliation(s)
- Patrick Gilon
- Université Catholique de Louvain, Institute of Experimental and Clinical Research, Pole of Endocrinology, Diabetes and Nutrition, Avenue Hippocrate 55 (B1.55.06), Brussels, B-1200, Belgium.
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Towers AE, Oelschlager ML, Juda MB, Jain S, Gainey SJ, Freund GG. HFD refeeding in mice after fasting impairs learning by activating caspase-1 in the brain. Metabolism 2020; 102:153989. [PMID: 31697963 PMCID: PMC6906226 DOI: 10.1016/j.metabol.2019.153989] [Citation(s) in RCA: 4] [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: 07/01/2019] [Revised: 09/10/2019] [Accepted: 10/01/2019] [Indexed: 01/07/2023]
Abstract
BACKGROUND Diets that include some aspect of fasting have dramatically increased in popularity. In addition, fasting reduces inflammasome activity in the brain while improving learning. Here, we examine the impact of refeeding a low-fat diet (LFD) or high-fat diet (HFD) after fasting. METHODS Male wildtype (WT), caspase-1 knockout (KO) and/or IL-1 receptor 1 (IL-1R1) KO mice were fasted for 24 h or allowed ad libitum access to food (chow). Immediately after fasting, mice were allowed to refeed for 2 h in the presence of LFD, HFD or chow. Mouse learning was examined using novel object recognition (NOR) and novel location recognition (NLR). Caspase-1 activity was quantified in the brain using histochemistry (HC) and image analysis. RESULTS Refeeding with a HFD but not a LFD or chow fully impaired both NOR and NLR. Likewise, HFD when compared to LFD refeeding increased caspase-1 activity in the whole amygdala and, particularly, in the posterior basolateral nuclei (BLp) by 2.5-fold and 4.6-fold, respectively. When caspase-1 KO or IL-1R1 KO mice were examined, learning impairment secondary to HFD refeeding did not occur. Equally, administration of n-acetylcysteine to fasted WT mice prevented HFD-dependent learning impairment and caspase-1 activation in the BLp. Finally, the free-fatty acid receptor 1 (FFAR1) antagonist, DC260126, mitigated learning impairment associated with HFD refeeding while blocking caspase-1 activation in the BLp. CONCLUSIONS Consumption of a HFD after fasting impairs learning by a mechanism that is dependent on caspase-1 and the IL-1R1 receptor. These consequences of a HFD refeeding on the BLP of the amygdala appear linked to oxidative stress and FFAR1.
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Affiliation(s)
- Albert E Towers
- Division of Nutritional Sciences, University of Illinois, Urbana, IL, USA
| | | | - Michal B Juda
- Department of Pathology, Program in Integrative Immunology and Behavior, University of Illinois, Urbana, IL, USA
| | - Sparsh Jain
- School of Molecular and Cellular Biology, University of Illinois, Urbana, IL, USA
| | - Stephen J Gainey
- Department of Animal Sciences, University of Illinois, Urbana, IL, USA
| | - Gregory G Freund
- Division of Nutritional Sciences, University of Illinois, Urbana, IL, USA; Department of Animal Sciences, University of Illinois, Urbana, IL, USA; Department of Pathology, Program in Integrative Immunology and Behavior, University of Illinois, Urbana, IL, USA.
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Noguchi GM, Huising MO. Integrating the inputs that shape pancreatic islet hormone release. Nat Metab 2019; 1:1189-1201. [PMID: 32694675 PMCID: PMC7378277 DOI: 10.1038/s42255-019-0148-2] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 11/07/2019] [Indexed: 02/06/2023]
Abstract
The pancreatic islet is a complex mini organ composed of a variety of endocrine cells and their support cells, which together tightly control blood glucose homeostasis. Changes in glucose concentration are commonly regarded as the chief signal controlling insulin-secreting beta cells, glucagon-secreting alpha cells and somatostatin-secreting delta cells. However, each of these cell types is highly responsive to a multitude of endocrine, paracrine, nutritional and neural inputs, which collectively shape the final endocrine output of the islet. Here, we review the principal inputs for each islet-cell type and the physiological circumstances in which these signals arise, through the prism of the insights generated by the transcriptomes of each of the major endocrine-cell types. A comprehensive integration of the factors that influence blood glucose homeostasis is essential to successfully improve therapeutic strategies for better diabetes management.
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Affiliation(s)
- Glyn M Noguchi
- Department of Neurobiology, Physiology & Behavior, College of Biological Sciences, University of California, Davis, Davis, CA, USA
| | - Mark O Huising
- Department of Neurobiology, Physiology & Behavior, College of Biological Sciences, University of California, Davis, Davis, CA, USA.
- Department of Physiology & Membrane Biology, School of Medicine, University of California, Davis, Davis, CA, USA.
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Liu W, Kin T, Ho S, Dorrell C, Campbell SR, Luo P, Chen X. Abnormal regulation of glucagon secretion by human islet alpha cells in the absence of beta cells. EBioMedicine 2019; 50:306-316. [PMID: 31780397 PMCID: PMC6921359 DOI: 10.1016/j.ebiom.2019.11.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 11/11/2019] [Accepted: 11/11/2019] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND The understanding of the regulation of glucagon secretion by pancreatic islet α-cells remains elusive. We aimed to develop an in vitro model for investigating the function of human α-cells under direct influence of glucose and other potential regulators. METHODS Highly purified human α-cells from islets of deceased donors were re-aggregated in the presence or absence of β-cells in culture, evaluated for glucagon secretion under various treatment conditions, and compared to that of intact human islets and non-sorted islet cell aggregates. FINDINGS The pure human α-cell aggregates maintained proper glucagon secretion capability at low concentrations of glucose, but failed to respond to changes in ambient glucose concentration. Addition of purified β-cells, but not the secreted factors from β-cells at low or high concentrations of glucose, partly restored the responsiveness of α-cells to glucose with regulated glucagon secretion. The EphA stimulator ephrinA5-fc failed to mimic the inhibitory effect of β-cells on glucagon secretion. Glibenclamide inhibited glucagon secretion from islets and the α- and β-mixed cell-aggregates, but not from the α-cell-only aggregates, at 2.0 mM glucose. INTERPRETATION This study validated the use of isolated and then re-aggregated human islet cells for investigating α-cell function and paracrine regulation, and demonstrated the importance of cell-to-cell contact between α- and β-cells on glucagon secretion. Loss of proper β- and α-cell physical interaction in islets likely contributes to the dysregulated glucagon secretion in diabetic patients. Re-aggregated select combinations of human islet cells provide unique platforms for studying islet cell function and regulation.
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Affiliation(s)
- Wei Liu
- Department of Nephropathy, The Second Hospital of Jilin University, 218 Ziquiang Street, Nanguan District, Changchun, Jilin 130041, China; Columbia Center for Translational Immunology, Department of Medicine, Columbia University Medical Center, New York, NY, USA
| | - Tatsuya Kin
- Clinical Islet Laboratory, University of Alberta, Edmonton, Alberta, Canada
| | - Siuhong Ho
- Columbia Center for Translational Immunology, Department of Medicine, Columbia University Medical Center, New York, NY, USA
| | - Craig Dorrell
- Oregon Stem Cell Center, Oregon Health & Science University, Portland, OR, USA
| | - Sean R Campbell
- Columbia Center for Translational Immunology, Department of Medicine, Columbia University Medical Center, New York, NY, USA
| | - Ping Luo
- Department of Nephropathy, The Second Hospital of Jilin University, 218 Ziquiang Street, Nanguan District, Changchun, Jilin 130041, China.
| | - Xiaojuan Chen
- Columbia Center for Translational Immunology, Department of Surgery, Columbia University Medical Center, 650 West 168th Street, BB1701, New York, NY 10032, USA.
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Briant LJB, Dodd MS, Chibalina MV, Rorsman NJG, Johnson PRV, Carmeliet P, Rorsman P, Knudsen JG. CPT1a-Dependent Long-Chain Fatty Acid Oxidation Contributes to Maintaining Glucagon Secretion from Pancreatic Islets. Cell Rep 2019; 23:3300-3311. [PMID: 29898400 PMCID: PMC6581793 DOI: 10.1016/j.celrep.2018.05.035] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 03/19/2018] [Accepted: 05/11/2018] [Indexed: 12/30/2022] Open
Abstract
Glucagon, the principal hyperglycemic hormone, is secreted from pancreatic islet α cells as part of the counter-regulatory response to hypoglycemia. Hence, secretory output from α cells is under high demand in conditions of low glucose supply. Many tissues oxidize fat as an alternate energy substrate. Here, we show that glucagon secretion in low glucose conditions is maintained by fatty acid metabolism in both mouse and human islets, and that inhibiting this metabolic pathway profoundly decreases glucagon output by depolarizing α cell membrane potential and decreasing action potential amplitude. We demonstrate, by using experimental and computational approaches, that this is not mediated by the KATP channel, but instead due to reduced operation of the Na+-K+ pump. These data suggest that counter-regulatory secretion of glucagon is driven by fatty acid metabolism, and that the Na+-K+ pump is an important ATP-dependent regulator of α cell function. Glucagon secretion in low glucose is maintained by CPT1a-dependent FAO Loss of CPT1a-dependent FAO in mouse and human islets decreases glucagon secretion CPT1a-dependent FAO maintains glucagon secretion by supplying ATP to the Na+-K+-ATPase CPT1a-dependent FAO contributes to the counter-regulatory secretion of glucagon
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Affiliation(s)
- Linford J B Briant
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 7LE, UK; Department of Computer Science, University of Oxford, Oxford OX1 3QD, UK
| | - Michael S Dodd
- Department of Physiology, Anatomy & Genetics, University of Oxford, Parks Road, Oxford OX1 3PT, UK; Faculty of Health and Life Sciences, Coventry University, Coventry CV1 5FB, UK
| | - Margarita V Chibalina
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 7LE, UK
| | - Nils J G Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 7LE, UK
| | - Paul R V Johnson
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 7LE, UK; Oxford National Institute for Health Research, Biomedical Research Centre, Churchill Hospital, Oxford OX3 7LJ, UK
| | - Peter Carmeliet
- Laboratory of Angiogenesis and Vascular Metabolism, VIB-KU Leuven Center for Cancer Biology, Leuven, Belgium
| | - Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 7LE, UK; Metabolic Research, Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Göteborg, Box 433, 405 30 Göteborg, Sweden
| | - Jakob G Knudsen
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 7LE, UK.
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Manell H, Kristinsson H, Kullberg J, Ubhayasekera SJK, Mörwald K, Staaf J, Cadamuro J, Zsoldos F, Göpel S, Sargsyan E, Ahlström H, Bergquist J, Weghuber D, Forslund A, Bergsten P. Hyperglucagonemia in youth is associated with high plasma free fatty acids, visceral adiposity, and impaired glucose tolerance. Pediatr Diabetes 2019; 20:880-891. [PMID: 31271247 DOI: 10.1111/pedi.12890] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 04/11/2019] [Accepted: 06/18/2019] [Indexed: 12/11/2022] Open
Abstract
OBJECTIVE To delineate potential mechanisms for fasting hyperglucagonemia in childhood obesity by studying the associations between fasting plasma glucagon concentrations and plasma lipid parameters and fat compartments. METHODS Cross-sectional study of children and adolescents with obesity (n = 147) and lean controls (n = 43). Differences in free fatty acids (FFAs), triglycerides, insulin, and fat compartments (quantified by magnetic resonance imaging) across quartiles of fasting plasma glucagon concentration were analyzed. Differences in oral glucose tolerance test (OGTT) glucagon response was tested in high vs low FFAs, triglycerides, and insulin. Human islets of Langerhans were cultured at 5.5 mmol/L glucose and in the absence or presence of a FFA mixture with total FFA concentration of 0.5 mmol/L and glucagon secretion quantified. RESULTS In children with obesity, the quartile with the highest fasting glucagon had higher insulin (201 ± 174 vs 83 ± 39 pmol/L, P < .01), FFAs (383 ± 52 vs 338 ± 109 μmol/L, P = .02), triglycerides (1.5 ± 0.9 vs 1.0 ± 0.7 mmol/L, P < .01), visceral adipose tissue volume (1.9 ± 0.8 vs 1.2 ± 0.3 dm3 , P < .001), and a higher prevalence of impaired glucose tolerance (IGT; 41% vs 8%, P = .01) than the lowest quartile. During OGTT, children with obesity and high insulin had a worse suppression of glucagon during the first 10 minutes after glucose intake. Glucagon secretion was 2.6-fold higher in islets treated with FFAs than in those not treated with FFAs. CONCLUSIONS Hyperglucagonemia in childhood obesity is associated with hyperinsulinemia, high plasma FFAs, high plasma triglycerides, visceral adiposity, and IGT. The glucagonotropic effect of FFAs on isolated human islets provides a potential mechanism linking high fasting plasma FFAs and glucagon levels.
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Affiliation(s)
- Hannes Manell
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden.,Department of Women's and Children's Health, Uppsala University, Uppsala, Sweden
| | | | - Joel Kullberg
- Department of Surgical Sciences, Radiology, Uppsala University, Uppsala, Sweden
| | | | - Katharina Mörwald
- Obesity Research Unit, Paracelsus Medical University, Salzburg, Austria
| | - Johan Staaf
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden.,Department of Women's and Children's Health, Uppsala University, Uppsala, Sweden
| | - Janne Cadamuro
- Department of Laboratory Medicine, Paracelsus Medical University, Salzburg, Austria
| | - Fanni Zsoldos
- Department of Laboratory Medicine, Paracelsus Medical University, Salzburg, Austria.,Department of Pediatrics, Paracelsus Medical University, Salzburg, Austria
| | - Sven Göpel
- Cardiovascular and Metabolic Diseases (CVMD), Innovative Medicines and Early Development Biotech Unit (iMed), AstraZeneca AB, Mölndal, Sweden
| | - Ernest Sargsyan
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Håkan Ahlström
- Department of Surgical Sciences, Radiology, Uppsala University, Uppsala, Sweden
| | - Jonas Bergquist
- Department of Chemistry-BMC, Analytical Chemistry & Neurochemistry, Uppsala University, Uppsala, Sweden
| | - Daniel Weghuber
- Department of Laboratory Medicine, Paracelsus Medical University, Salzburg, Austria.,Department of Pediatrics, Paracelsus Medical University, Salzburg, Austria
| | - Anders Forslund
- Department of Women's and Children's Health, Uppsala University, Uppsala, Sweden
| | - Peter Bergsten
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden.,Department of Women's and Children's Health, Uppsala University, Uppsala, Sweden
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Hanikoglu A, Kucuksayan E, Hanikoglu F, Ozben T, Menounou G, Sansone A, Chatgilialoglu C, Di Bella G, Ferreri C. Effects of somatostatin, curcumin, and quercetin on the fatty acid profile of breast cancer cell membranes. Can J Physiol Pharmacol 2019; 98:131-138. [PMID: 31545905 DOI: 10.1139/cjpp-2019-0352] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Breast cancer is a worldwide commonly found malignancy in women and effective treatment is regarded as a huge clinical challenge even in the presence of several treatment options. Extensive literature is available demonstrating polyphenols as phytopharmaceutical anticancer agents. Among the polyphenols, quercetin and curcumin have been reported to have a strong potential against breast cancer. However, so far, no comprehensive study has been performed to demonstrate the anticarcinogenic effects of curcumin, quercetin, and their combinations with somatostatin on the fatty acid profile of breast cancer cell membranes. We used MCF-7 and MDA-MB231 breast cancer cells incubated with curcumin and quercetin for 24 h, in the absence and presence of somatostatin, at their EC50 concentrations to evaluate membrane fatty acid based functional lipidomics together with the followup of EGFR and MAPK signaling pathways. The two cell lines gave different membrane free fatty acid reorganization. In MCF-7 cells, the following changes were observed: an increase of ω6 linoleic acid in the cells incubated with somatostatin + quercetin and quercetin and a decrease of ω3 acids in the cells incubated with somatostatin + curcumin compared to somatostatin and significant increases of monounsaturated fatty acid (MUFA), mono-trans arachidonic acid levels and docosapentaenoic acid for the cells incubated with somatostatin + quercetin compared to the control cells. In MDA-MB231 cells, incubations with curcumin, quercetin, and somatostatin + quercetin induced the most significant membrane remodeling with the increase of stearic acid, diminution of ω6 linoleic, arachidonic acids, and ω3 (docosapentaenoic and docosahexaenoic acids). Distinct signaling pathway changes were found for these cell lines. In MCF-7 cells, separate or combined incubations with somatostatin and quercetin, significantly decreased EGFR and incubation with curcumin decreased MAPK signaling. In MDA-MB231 cells, incubation with curcumin decreased AKT1 and p-AKT1 (Thr308) levels. Incubation with curcumin and quercetin decreased the EGFR levels. Our results showed that cytostatic and antioxidant treatments can be combined to induce membrane fatty acid changes, including lipid isomerization as specific free radical driven process, and to influence signaling pathways. This study aimed to contribute to the literature on these antioxidants in the treatment of breast cancer to clarify the effects and mechanisms in combination with somatostatin.
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Affiliation(s)
- Aysegul Hanikoglu
- Department of Biochemistry, Faculty of Pharmacy, Biruni University, Istanbul, Turkey
| | - Ertan Kucuksayan
- Department of Biochemistry, Faculty of Medicine, Alanya Alaaddin Keykubat University, Antalya, Turkey
| | - Ferhat Hanikoglu
- Department of Biochemistry, Faculty of Medicine, Biruni University, Istanbul, Turkey
| | - Tomris Ozben
- Department of Biochemistry, Faculty of Medicine, Akdeniz University, 07070 Antalya, Turkey
| | - Georgia Menounou
- Consiglio Nazionale delle Ricerche, ISOF, Via Piero Gobetti 101, 40129 Bologna, Italy
| | - Anna Sansone
- Consiglio Nazionale delle Ricerche, ISOF, Via Piero Gobetti 101, 40129 Bologna, Italy
| | - Chrys Chatgilialoglu
- Consiglio Nazionale delle Ricerche, ISOF, Via Piero Gobetti 101, 40129 Bologna, Italy
| | | | - Carla Ferreri
- Consiglio Nazionale delle Ricerche, ISOF, Via Piero Gobetti 101, 40129 Bologna, Italy
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Galsgaard KD, Pedersen J, Knop FK, Holst JJ, Wewer Albrechtsen NJ. Glucagon Receptor Signaling and Lipid Metabolism. Front Physiol 2019; 10:413. [PMID: 31068828 PMCID: PMC6491692 DOI: 10.3389/fphys.2019.00413] [Citation(s) in RCA: 108] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2018] [Accepted: 03/26/2019] [Indexed: 01/04/2023] Open
Abstract
Glucagon is secreted from the pancreatic alpha cells upon hypoglycemia and stimulates hepatic glucose production. Type 2 diabetes is associated with dysregulated glucagon secretion, and increased glucagon concentrations contribute to the diabetic hyperglycemia. Antagonists of the glucagon receptor have been considered as glucose-lowering therapy in type 2 diabetes patients, but their clinical applicability has been questioned because of reports of therapy-induced increments in liver fat content and increased plasma concentrations of low-density lipoprotein. Conversely, in animal models, increased glucagon receptor signaling has been linked to improved lipid metabolism. Glucagon acts primarily on the liver and by regulating hepatic lipid metabolism glucagon may reduce hepatic lipid accumulation and decrease hepatic lipid secretion. Regarding whole-body lipid metabolism, it is controversial to what extent glucagon influences lipolysis in adipose tissue, particularly in humans. Glucagon receptor agonists combined with glucagon-like peptide 1 receptor agonists (dual agonists) improve dyslipidemia and reduce hepatic steatosis. Collectively, emerging data support an essential role of glucagon for lipid metabolism.
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Affiliation(s)
- Katrine D Galsgaard
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jens Pedersen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Cardiology, Nephrology and Endocrinology, Nordsjællands Hospital Hillerød, University of Copenhagen, Hillerød, Denmark
| | - Filip K Knop
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Clinical Metabolic Physiology, Steno Diabetes Center Copenhagen, Gentofte Hospital, Hellerup, Denmark.,Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jens J Holst
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Nicolai J Wewer Albrechtsen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Clinical Biochemistry, Rigshospitalet, Copenhagen, Denmark.,Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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39
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Hanikoglu A, Kucuksayan E, Hanikoglu F, Ozben T, Menounou G, Sansone A, Chatgilialoglu C, Di Bella G, Ferreri C. Effects of Somatostatin and Vitamin C on the Fatty Acid Profile of Breast Cancer Cell Membranes. Anticancer Agents Med Chem 2019; 19:1899-1909. [DOI: 10.2174/1871520619666190930130732] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 07/16/2019] [Accepted: 07/17/2019] [Indexed: 12/12/2022]
Abstract
Background:Vitamin C (Vit C) is an important physiological antioxidant with growing applications in cancer. Somatostatin (SST) is a natural peptide with growth inhibitory effect in several mammary cancer models.Objective:The combined effects of SST and Vit C supplementation have never been studied in breast cancer cells so far.Methods:We used MCF-7 and MDA-MB231 breast cancer cells incubated with SST for 24h, in the absence and presence of Vit C, at their EC50 concentrations, to evaluate membrane fatty acid-profiles together with the follow-up of EGFR and MAPK signaling pathways.Results:The two cell lines gave different membrane reorganization: in MCF-7 cells, decrease of omega-6 linoleic acid and increase of omega-3 fatty acids (Fas) occurred after SST and SST+Vit C incubations, the latter also showing significant increases in MUFA, docosapentaenoic acid and mono-trans arachidonic acid levels. In MDA-MB231 cells, SST+Vit C incubation induced significant membrane remodeling with an increase of stearic acid and mono-trans-linoleic acid isomer, diminution of omega-6 linoleic, arachidonic acid and omega-3 (docosapentaenoic and docosadienoic acids). Distinct signaling pathways in these cell lines were studies: in MCF-7 cells, incubations with SST and Vit C, alone or in combination significantly decreased EGFR and MAPK signaling, whereas in MDA-MB231 cells, SST and Vit C incubations, alone or combined, decreased p-P44/42 MAPK levels, and increased EGFR levels.Conclusion:Our results showed that SST and Vit C can be combined to induce membrane fatty acid changes, including lipid isomerization through a specific free radical-driven process, influencing signaling pathways.
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Affiliation(s)
- Aysegul Hanikoglu
- Department of Biochemistry, Faculty of Medicine, Akdeniz University, 07070 Antalya, Turkey
| | - Ertan Kucuksayan
- Department of Biochemistry, Faculty of Medicine, Alanya Alaaddin Keykubat University, Antalya, Turkey
| | - Ferhat Hanikoglu
- Department of Biochemistry, Faculty of Medicine, Biruni University, Istanbul, Turkey
| | - Tomris Ozben
- Department of Biochemistry, Faculty of Medicine, Akdeniz University, 07070 Antalya, Turkey
| | - Georgia Menounou
- Consiglio Nazionale delle Ricerche, ISOF, Via Piero Gobetti 101, 40129 Bologna, Italy
| | - Anna Sansone
- Consiglio Nazionale delle Ricerche, ISOF, Via Piero Gobetti 101, 40129 Bologna, Italy
| | - Chrys Chatgilialoglu
- Consiglio Nazionale delle Ricerche, ISOF, Via Piero Gobetti 101, 40129 Bologna, Italy
| | | | - Carla Ferreri
- Consiglio Nazionale delle Ricerche, ISOF, Via Piero Gobetti 101, 40129 Bologna, Italy
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40
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Tse LH, Wong YH. GPCRs in Autocrine and Paracrine Regulations. Front Endocrinol (Lausanne) 2019; 10:428. [PMID: 31354618 PMCID: PMC6639758 DOI: 10.3389/fendo.2019.00428] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Accepted: 06/14/2019] [Indexed: 12/17/2022] Open
Abstract
G protein-coupled receptors (GPCRs) constitute the largest superfamily of integral membrane protein receptors. As signal detectors, the several 100 known GPCRs are responsible for sensing the plethora of endogenous ligands that are critical for the functioning of our endocrine system. Although GPCRs are typically considered as detectors for first messengers in classical signal transduction pathways, they seldom operate in isolation in complex biological systems. Intercellular communication between identical or different cell types is often mediated by autocrine or paracrine signals that are generated upon activation of specific GPCRs. In the context of energy homeostasis, the distinct complement of GPCRs in each cell type bridges the autocrine and paracrine communication within an organ, and the various downstream signaling mechanisms regulated by GPCRs can be integrated in a cell to produce an ultimate output. GPCRs thus act as gatekeepers that coordinate and fine-tune a response. By examining the role of GPCRs in activating and receiving autocrine and paracrine signals, one may have a better understanding of endocrine diseases that are associated with GPCR mutations, thereby providing new insights for treatment regimes.
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Affiliation(s)
- Lap Hang Tse
- Division of Life Science, Biotechnology Research Institute, Hong Kong University of Science and Technology, Hong Kong, Hong Kong
| | - Yung Hou Wong
- Division of Life Science, Biotechnology Research Institute, Hong Kong University of Science and Technology, Hong Kong, Hong Kong
- State Key Laboratory of Molecular Neuroscience, Molecular Neuroscience Center, Hong Kong University of Science and Technology, Hong Kong, Hong Kong
- *Correspondence: Yung Hou Wong
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Hastoy B, Godazgar M, Clark A, Nylander V, Spiliotis I, van de Bunt M, Chibalina MV, Barrett A, Burrows C, Tarasov AI, Scharfmann R, Gloyn AL, Rorsman P. Electrophysiological properties of human beta-cell lines EndoC-βH1 and -βH2 conform with human beta-cells. Sci Rep 2018; 8:16994. [PMID: 30451893 PMCID: PMC6242937 DOI: 10.1038/s41598-018-34743-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 10/19/2018] [Indexed: 12/30/2022] Open
Abstract
Limited access to human islets has prompted the development of human beta cell models. The human beta cell lines EndoC-βH1 and EndoC-βH2 are increasingly used by the research community. However, little is known of their electrophysiological and secretory properties. Here, we monitored parameters that constitute the glucose-triggering pathway of insulin release. Both cell lines respond to glucose (6 and 20 mM) with 2- to 3-fold stimulation of insulin secretion which correlated with an elevation of [Ca2+]i, membrane depolarisation and increased action potential firing. Similar to human primary beta cells, KATP channel activity is low at 1 mM glucose and is further reduced upon increasing glucose concentration; an effect that was mimicked by the KATP channel blocker tolbutamide. The upstroke of the action potentials reflects the activation of Ca2+ channels with some small contribution of TTX-sensitive Na+ channels. The repolarisation involves activation of voltage-gated Kv2.2 channels and large-conductance Ca2+-activated K+ channels. Exocytosis presented a similar kinetics to human primary beta cells. The ultrastructure of these cells shows insulin vesicles composed of an electron-dense core surrounded by a thin clear halo. We conclude that the EndoC-βH1 and -βH2 cells share many features of primary human β-cells and thus represent a useful experimental model.
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Affiliation(s)
- Benoît Hastoy
- 0000 0004 1936 8948grid.4991.5Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Mahdieh Godazgar
- 0000 0004 1936 8948grid.4991.5Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Anne Clark
- 0000 0004 1936 8948grid.4991.5Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Vibe Nylander
- 0000 0004 1936 8948grid.4991.5Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Ioannis Spiliotis
- 0000 0004 1936 8948grid.4991.5Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Martijn van de Bunt
- 0000 0004 1936 8948grid.4991.5Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom ,0000 0004 1936 8948grid.4991.5Wellcome Centre for Human Genetics, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Margarita V. Chibalina
- 0000 0004 1936 8948grid.4991.5Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Amy Barrett
- 0000 0004 1936 8948grid.4991.5Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Carla Burrows
- 0000 0004 1936 8948grid.4991.5Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Andrei I. Tarasov
- 0000 0004 1936 8948grid.4991.5Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Raphael Scharfmann
- 0000 0001 2188 0914grid.10992.33INSERM U1016, Cochin Institute, Université Paris Descartes, Paris, France
| | - Anna L. Gloyn
- 0000 0004 1936 8948grid.4991.5Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom ,0000 0004 1936 8948grid.4991.5Wellcome Centre for Human Genetics, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom ,0000 0004 0488 9484grid.415719.fNational Institute for Health Research (NIHR) Oxford Biomedical Research Centre, Churchill Hospital, Oxford, United Kingdom
| | - Patrik Rorsman
- 0000 0004 1936 8948grid.4991.5Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom ,0000 0004 0488 9484grid.415719.fNational Institute for Health Research (NIHR) Oxford Biomedical Research Centre, Churchill Hospital, Oxford, United Kingdom ,0000 0000 9919 9582grid.8761.8Department of Physiology, Institute of Neuroscience and Physiology, University of Goteborg, Goteborg, Sweden
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Cen J, Sargsyan E, Forslund A, Bergsten P. Mechanisms of beneficial effects of metformin on fatty acid-treated human islets. J Mol Endocrinol 2018; 61:91-99. [PMID: 30307162 DOI: 10.1530/jme-17-0304] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Elevated levels of palmitate accentuate glucose-stimulated insulin secretion (GSIS) after short-term and cause beta-cell dysfunction after prolonged exposure. We investigated whether metformin, the first-line oral drug for treatment of T2DM, has beneficial effects on FFA-treated human islets and the potential mechanisms behind the effects. Insulin secretion, oxygen consumption rate (OCR), AMPK activation, endoplasmic reticulum (ER) stress and apoptosis were examined in isolated human islets after exposure to elevated levels of palmitate in the absence or presence of metformin. Palmitate exposure doubled GSIS after 2 days but halved after 7 days compared with control. Inclusion of metformin during palmitate exposure normalized insulin secretion both after 2 and 7 days. After 2-day exposure to palmitate, OCR and the marker of the adaptive arm of ER stress response (sorcin) were significantly raised, whereas AMPK phosphorylation, markers of pro-apoptotic arm of ER stress response (p-EIF2α and CHOP) and apoptosis (cleaved caspase 3) were not affected. Presence of metformin during 2-day palmitate exposure normalized OCR and sorcin levels. After 7-day exposure to palmitate, OCR and sorcin were not significantly different from control level, p-AMPK was reduced and p-EIF2α, CHOP and cleaved caspase 3 were strongly upregulated. Presence of metformin during 7-day culture with palmitate normalized the level of p-AMPK, p-EIF2α, CHOP and cleaved caspase 3 but significantly increased the level of sorcin. Our study demonstrates that metformin prevents early insulin hypersecretion and later decrease in insulin secretion from palmitate-treated human islets by utilizing different mechanisms.
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Affiliation(s)
- Jing Cen
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Ernest Sargsyan
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
- Molecular Neuroscience Group, Institute of Molecular Biology, National Academy of Sciences, Yerevan, Armenia
| | - Anders Forslund
- Department of Women’s and Children’s Health, Uppsala University, Uppsala, Sweden
| | - Peter Bergsten
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
- Department of Women’s and Children’s Health, Uppsala University, Uppsala, Sweden
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Fatty Acid-Stimulated Insulin Secretion vs. Lipotoxicity. Molecules 2018; 23:molecules23061483. [PMID: 29921789 PMCID: PMC6100479 DOI: 10.3390/molecules23061483] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 06/13/2018] [Accepted: 06/15/2018] [Indexed: 12/29/2022] Open
Abstract
Fatty acid (FA)-stimulated insulin secretion (FASIS) is reviewed here in contrast to type 2 diabetes etiology, resulting from FA overload, oxidative stress, intermediate hyperinsulinemia, and inflammation, all converging into insulin resistance. Focusing on pancreatic islet β-cells, we compare the physiological FA roles with the pathological ones. Considering FAs not as mere amplifiers of glucose-stimulated insulin secretion (GSIS), but as parallel insulin granule exocytosis inductors, partly independent of the KATP channel closure, we describe the FA initiating roles in the prediabetic state that is induced by retardations in the glycerol-3-phosphate (glucose)-promoted glycerol/FA cycle and by the impaired GPR40/FFA1 (free FA1) receptor pathway, specifically in its amplification by the redox-activated mitochondrial phospholipase, iPLA2γ. Also, excessive dietary FAs stimulate intestine enterocyte incretin secretion, further elevating GSIS, even at low glucose levels, thus contributing to diabetic hyperinsulinemia. With overnutrition and obesity, the FA overload causes impaired GSIS by metabolic dysbalance, paralleled by oxidative and metabolic stress, endoplasmic reticulum stress and numerous pro-apoptotic signaling, all leading to decreased β-cell survival. Lipotoxicity is exerted by saturated FAs, whereas ω-3 polyunsaturated FAs frequently exert antilipotoxic effects. FA-facilitated inflammation upon the recruitment of excess M1 macrophages into islets (over resolving M2 type), amplified by cytokine and chemokine secretion by β-cells, leads to an inevitable failure of pancreatic β-cells.
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20-HETE promotes glucose-stimulated insulin secretion in an autocrine manner through FFAR1. Nat Commun 2018; 9:177. [PMID: 29330456 PMCID: PMC5766607 DOI: 10.1038/s41467-017-02539-4] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 12/07/2017] [Indexed: 01/02/2023] Open
Abstract
The long-chain fatty acid receptor FFAR1 is highly expressed in pancreatic β-cells. Synthetic FFAR1 agonists can be used as antidiabetic drugs to promote glucose-stimulated insulin secretion (GSIS). However, the physiological role of FFAR1 in β-cells remains poorly understood. Here we show that 20-HETE activates FFAR1 and promotes GSIS via FFAR1 with higher potency and efficacy than dietary fatty acids such as palmitic, linoleic, and α-linolenic acid. Murine and human β-cells produce 20-HETE, and the ω-hydroxylase-mediated formation and release of 20-HETE is strongly stimulated by glucose. Pharmacological inhibition of 20-HETE formation and blockade of FFAR1 in islets inhibits GSIS. In islets from type-2 diabetic humans and mice, glucose-stimulated 20-HETE formation and 20-HETE-dependent stimulation of GSIS are strongly reduced. We show that 20-HETE is an FFAR1 agonist, which functions as an autocrine positive feed-forward regulator of GSIS, and that a reduced glucose-induced 20-HETE formation contributes to inefficient GSIS in type-2 diabetes. FFAR1 receptor is highly expressed in beta cells and its activation has been suggested as therapy against type-2 diabetes. Here, Tunaru et al. show that 20-hydroxyeicosatetraenoic acid, produced within the islets upon glucose stimulation, acts in an autocrine manner to stimulate insulin secretion via FFAR1 activation.
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Paternoster S, Falasca M. Dissecting the Physiology and Pathophysiology of Glucagon-Like Peptide-1. Front Endocrinol (Lausanne) 2018; 9:584. [PMID: 30364192 PMCID: PMC6193070 DOI: 10.3389/fendo.2018.00584] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 09/14/2018] [Indexed: 12/11/2022] Open
Abstract
An aging world population exposed to a sedentary life style is currently plagued by chronic metabolic diseases, such as type-2 diabetes, that are spreading worldwide at an unprecedented rate. One of the most promising pharmacological approaches for the management of type 2 diabetes takes advantage of the peptide hormone glucagon-like peptide-1 (GLP-1) under the form of protease resistant mimetics, and DPP-IV inhibitors. Despite the improved quality of life, long-term treatments with these new classes of drugs are riddled with serious and life-threatening side-effects, with no overall cure of the disease. New evidence is shedding more light over the complex physiology of GLP-1 in health and metabolic diseases. Herein, we discuss the most recent advancements in the biology of gut receptors known to induce the secretion of GLP-1, to bridge the multiple gaps into our understanding of its physiology and pathology.
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