51
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Hoffman EG, Jahangiriesmaili M, Mandel ER, Greenberg C, Aiken J, D’Souza NC, Pasieka A, Teich T, Chan O, Liggins R, Riddell MC. Somatostatin Receptor Antagonism Reverses Glucagon Counterregulatory Failure in Recurrently Hypoglycemic Male Rats. Endocrinology 2021; 162:6363563. [PMID: 34477204 PMCID: PMC8482965 DOI: 10.1210/endocr/bqab189] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Indexed: 12/12/2022]
Abstract
Recent antecedent hypoglycemia is a known source of defective glucose counter-regulation in diabetes; the mechanisms perpetuating the cycle of progressive α-cell failure and recurrent hypoglycemia remain unknown. Somatostatin has been shown to suppress the glucagon response to acute hypoglycemia in rodent models of type 1 diabetes. We hypothesized that somatostatin receptor 2 antagonism (SSTR2a) would restore glucagon counterregulation and delay the onset of insulin-induced hypoglycemia in recurrently hypoglycemic, nondiabetic male rats. Healthy, male, Sprague-Dawley rats (n = 39) received bolus injections of insulin (10 U/kg, 8 U/kg, 5 U/kg) on 3 consecutive days to induce hypoglycemia. On day 4, animals were then treated with SSTR2a (10 mg/kg; n = 17) or vehicle (n = 12) 1 hour prior to the induction of hypoglycemia using insulin (5 U/kg). Plasma glucagon level during hypoglycemia was ~30% lower on day 3 (150 ± 75 pg/mL; P < .01), and 68% lower on day 4 in the vehicle group (70 ± 52 pg/mL; P < .001) compared with day 1 (219 ± 99 pg/mL). On day 4, SSTR2a prolonged euglycemia by 25 ± 5 minutes (P < .05) and restored the plasma glucagon response to hypoglycemia. Hepatic glycogen content of SSTR2a-treated rats was 35% lower than vehicle controls after hypoglycemia induction on day 4 (vehicle: 20 ± 7.0 vs SSTR2a: 13 ± 4.4 µmol/g; P < .01). SSTR2a treatment reverses the cumulative glucagon deficit resulting from 3 days of antecedent hypoglycemia in healthy rats. This reversal is associated with decreased hepatic glycogen content and delayed time to hypoglycemic onset. We conclude that recurrent hypoglycemia produces glucagon counterregulatory deficiency in healthy male rats, which can be improved by SSTR2a.
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Affiliation(s)
- Emily G Hoffman
- School of Kinesiology and Health Science, Muscle Health Research Centre, York University, Toronto, ON M3J 1P3, Canada
| | - Mahsa Jahangiriesmaili
- School of Kinesiology and Health Science, Muscle Health Research Centre, York University, Toronto, ON M3J 1P3, Canada
| | - Erin R Mandel
- School of Kinesiology and Health Science, Muscle Health Research Centre, York University, Toronto, ON M3J 1P3, Canada
| | - Caylee Greenberg
- School of Kinesiology and Health Science, Muscle Health Research Centre, York University, Toronto, ON M3J 1P3, Canada
| | - Julian Aiken
- School of Kinesiology and Health Science, Muscle Health Research Centre, York University, Toronto, ON M3J 1P3, Canada
| | - Ninoschka C D’Souza
- School of Kinesiology and Health Science, Muscle Health Research Centre, York University, Toronto, ON M3J 1P3, Canada
| | - Aoibhe Pasieka
- School of Kinesiology and Health Science, Muscle Health Research Centre, York University, Toronto, ON M3J 1P3, Canada
| | - Trevor Teich
- School of Kinesiology and Health Science, Muscle Health Research Centre, York University, Toronto, ON M3J 1P3, Canada
| | - Owen Chan
- Department of Internal Medicine—Division of Endocrinology, Metabolism and Diabetes, University of Utah, Salt Lake City, UT 84112, USA
| | | | - Michael C Riddell
- School of Kinesiology and Health Science, Muscle Health Research Centre, York University, Toronto, ON M3J 1P3, Canada
- Correspondence: Michael C. Riddell, PhD, School of Kinesiology and Health Science, Muscle Health Research Centre, York University, 4700 Keele Street, Toronto, ON, Canada, M3J 1P3.
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Kim A, Knudsen JG, Madara JC, Benrick A, Hill TG, Abdul Kadir L, Kellard JA, Mellander L, Miranda C, Lin H, James T, Suba K, Spigelman AF, Wu Y, MacDonald PE, Wernstedt Asterholm I, Magnussen T, Christensen M, Vilsbøll T, Salem V, Knop FK, Rorsman P, Lowell BB, Briant LJB. Arginine-vasopressin mediates counter-regulatory glucagon release and is diminished in type 1 diabetes. eLife 2021; 10:e72919. [PMID: 34787082 PMCID: PMC8654374 DOI: 10.7554/elife.72919] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 11/16/2021] [Indexed: 01/27/2023] Open
Abstract
Insulin-induced hypoglycemia is a major treatment barrier in type-1 diabetes (T1D). Accordingly, it is important that we understand the mechanisms regulating the circulating levels of glucagon. Varying glucose over the range of concentrations that occur physiologically between the fed and fuel-deprived states (8 to 4 mM) has no significant effect on glucagon secretion in the perfused mouse pancreas or in isolated mouse islets (in vitro), and yet associates with dramatic increases in plasma glucagon. The identity of the systemic factor(s) that elevates circulating glucagon remains unknown. Here, we show that arginine-vasopressin (AVP), secreted from the posterior pituitary, stimulates glucagon secretion. Alpha-cells express high levels of the vasopressin 1b receptor (V1bR) gene (Avpr1b). Activation of AVP neurons in vivo increased circulating copeptin (the C-terminal segment of the AVP precursor peptide) and increased blood glucose; effects blocked by pharmacological antagonism of either the glucagon receptor or V1bR. AVP also mediates the stimulatory effects of hypoglycemia produced by exogenous insulin and 2-deoxy-D-glucose on glucagon secretion. We show that the A1/C1 neurons of the medulla oblongata drive AVP neuron activation in response to insulin-induced hypoglycemia. AVP injection increased cytoplasmic Ca2+ in alpha-cells (implanted into the anterior chamber of the eye) and glucagon release. Hypoglycemia also increases circulating levels of AVP/copeptin in humans and this hormone stimulates glucagon secretion from human islets. In patients with T1D, hypoglycemia failed to increase both copeptin and glucagon. These findings suggest that AVP is a physiological systemic regulator of glucagon secretion and that this mechanism becomes impaired in T1D.
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Affiliation(s)
- Angela Kim
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical CenterBostonUnited States
- Program in Neuroscience, Harvard Medical SchoolBostonUnited States
| | - Jakob G Knudsen
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of OxfordOxfordUnited Kingdom
- Section for Cell Biology and Physiology, Department of Biology, University of CopenhagenCopenhagenDenmark
| | - Joseph C Madara
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical CenterBostonUnited States
| | - Anna Benrick
- Metabolic Research Unit, Institute of Neuroscience and Physiology, Sahlgrenska Academy at University of GothenburgGöteborgSweden
| | - Thomas G Hill
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of OxfordOxfordUnited Kingdom
| | - Lina Abdul Kadir
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of OxfordOxfordUnited Kingdom
| | - Joely A Kellard
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of OxfordOxfordUnited Kingdom
| | - Lisa Mellander
- Metabolic Research Unit, Institute of Neuroscience and Physiology, Sahlgrenska Academy at University of GothenburgGöteborgSweden
| | - Caroline Miranda
- Metabolic Research Unit, Institute of Neuroscience and Physiology, Sahlgrenska Academy at University of GothenburgGöteborgSweden
| | - Haopeng Lin
- Alberta Diabetes Institute, Li Ka Shing Centre for Health Research InnovationEdmontonCanada
| | - Timothy James
- Department of Clinical Biochemistry, John Radcliffe, Oxford NHS TrustOxfordUnited Kingdom
| | - Kinga Suba
- Section of Cell Biology and Functional Genomics, Department of Metabolism, Digestion and Reproduction, Imperial College LondonLondonUnited Kingdom
| | - Aliya F Spigelman
- Alberta Diabetes Institute, Li Ka Shing Centre for Health Research InnovationEdmontonCanada
| | - Yanling Wu
- Metabolic Research Unit, Institute of Neuroscience and Physiology, Sahlgrenska Academy at University of GothenburgGöteborgSweden
| | - Patrick E MacDonald
- Alberta Diabetes Institute, Li Ka Shing Centre for Health Research InnovationEdmontonCanada
| | - Ingrid Wernstedt Asterholm
- Metabolic Research Unit, Institute of Neuroscience and Physiology, Sahlgrenska Academy at University of GothenburgGöteborgSweden
| | - Tore Magnussen
- Center for Clinical Metabolic Research, Gentofte HospitalHellerupDenmark
| | - Mikkel Christensen
- Center for Clinical Metabolic Research, Gentofte HospitalHellerupDenmark
- Department of Clinical Pharmacology, Bispebjerg Hospital, University of CopenhagenCopenhagenDenmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of CopenhagenCopenhagenDenmark
| | - Tina Vilsbøll
- Center for Clinical Metabolic Research, Gentofte HospitalHellerupDenmark
- Department of Clinical Pharmacology, Bispebjerg Hospital, University of CopenhagenCopenhagenDenmark
- Steno Diabetes Center CopenhagenCopenhagenDenmark
| | - Victoria Salem
- Section of Cell Biology and Functional Genomics, Department of Metabolism, Digestion and Reproduction, Imperial College LondonLondonUnited Kingdom
| | - Filip K Knop
- Center for Clinical Metabolic Research, Gentofte HospitalHellerupDenmark
- Department of Clinical Pharmacology, Bispebjerg Hospital, University of CopenhagenCopenhagenDenmark
- Steno Diabetes Center CopenhagenCopenhagenDenmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of CopenhagenCopenhagenDenmark
| | - Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of OxfordOxfordUnited Kingdom
- Metabolic Research Unit, Institute of Neuroscience and Physiology, Sahlgrenska Academy at University of GothenburgGöteborgSweden
| | - Bradford B Lowell
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical CenterBostonUnited States
- Program in Neuroscience, Harvard Medical SchoolBostonUnited States
| | - Linford JB Briant
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of OxfordOxfordUnited Kingdom
- Department of Computer Science, University of OxfordOxfordUnited Kingdom
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Romero-Campos HE, Dupont G, Gonzalez-Velez V. On the Electrophysiological Component of Pancreatic Alpha-Cell Models. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2021; 2021:4408-4411. [PMID: 34892197 DOI: 10.1109/embc46164.2021.9630329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Glucagon, the main hormone responsible for increasing blood glucose levels, is secreted by pancreatic alphacells in a Ca2+ dependent process associated to membrane potential oscillations developed by the dynamic operation of K+, Na+ and Ca2+ channels. The mechanisms behind membrane potential and Ca2+ oscillations in alpha-cells are still under debate, and some new research works have used alpha-cell models to describe electrical activity. In this paper we studied the dynamics of electrical activity of three alpha-cell models using the Lead Potential Analysis method and Bifurcation Diagrams. Our aim is to highlight the differences in their dynamic behavior and therefore, in their response to glucose. Both issues are relevant to understand the stimulus-secretion coupling in alpha-cells and then, the mechanisms behind their dysregulation in Type 2 Diabetes.Clinical Relevance - A reliable description of the electrophysiological mechanisms in pancreatic alpha-cells is key to understand and treat the dysregulation of these cells in patients with Type 2 Diabetes.
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Asadi F, Dhanvantari S. Pathways of Glucagon Secretion and Trafficking in the Pancreatic Alpha Cell: Novel Pathways, Proteins, and Targets for Hyperglucagonemia. Front Endocrinol (Lausanne) 2021; 12:726368. [PMID: 34659118 PMCID: PMC8511682 DOI: 10.3389/fendo.2021.726368] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 09/13/2021] [Indexed: 12/15/2022] Open
Abstract
Patients with diabetes mellitus exhibit hyperglucagonemia, or excess glucagon secretion, which may be the underlying cause of the hyperglycemia of diabetes. Defective alpha cell secretory responses to glucose and paracrine effectors in both Type 1 and Type 2 diabetes may drive the development of hyperglucagonemia. Therefore, uncovering the mechanisms that regulate glucagon secretion from the pancreatic alpha cell is critical for developing improved treatments for diabetes. In this review, we focus on aspects of alpha cell biology for possible mechanisms for alpha cell dysfunction in diabetes: proglucagon processing, intrinsic and paracrine control of glucagon secretion, secretory granule dynamics, and alterations in intracellular trafficking. We explore possible clues gleaned from these studies in how inhibition of glucagon secretion can be targeted as a treatment for diabetes mellitus.
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Affiliation(s)
- Farzad Asadi
- Department of Pathology and Laboratory Medicine, Western University, London, ON, Canada
- Program in Metabolism and Diabetes, Lawson Health Research Institute, London, ON, Canada
| | - Savita Dhanvantari
- Department of Pathology and Laboratory Medicine, Western University, London, ON, Canada
- Program in Metabolism and Diabetes, Lawson Health Research Institute, London, ON, Canada
- Imaging Research Program, Lawson Health Research Institute, London, ON, Canada
- Department of Medical Biophysics, Western University, London, ON, Canada
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55
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Kuhre RE, Deacon CF, Wewer Albrechtsen NJ, Holst JJ. Do sodium-glucose co-transporter-2 inhibitors increase plasma glucagon by direct actions on the alpha cell? And does the increase matter for the associated increase in endogenous glucose production? Diabetes Obes Metab 2021; 23:2009-2019. [PMID: 33961344 DOI: 10.1111/dom.14422] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 04/21/2021] [Accepted: 05/04/2021] [Indexed: 12/12/2022]
Abstract
Sodium-glucose co-transporter-2 inhibitors (SGLT2is) lower blood glucose and are used for treatment of type 2 diabetes. However, SGLT2is have been associated with increases in endogenous glucose production (EGP) by mechanisms that have been proposed to result from SGLT2i-mediated increases in circulating glucagon concentrations, but the relative importance of this effect is debated, and mechanisms possibly coupling SGLT2is to increased plasma glucagon are unclear. A direct effect on alpha-cell activity has been proposed, but data on alpha-cell SGLT2 expression are inconsistent, and studies investigating the direct effects of SGLT2 inhibition on glucagon secretion are conflicting. By contrast, alpha-cell sodium-glucose co-transporter-1 (SGLT1) expression has been found more consistently and appears to be more prominent, pointing to an underappreciated role for this transporter. Nevertheless, the selectivity of most SGLT2is does not support interference with SGLT1 during therapy. Paracrine effects mediated by secretion of glucagonotropic/static molecules from beta and/or delta cells have also been suggested to be involved in SGLT2i-induced increase in plasma glucagon, but studies are few and arrive at different conclusions. It is also possible that the effect on glucagon is secondary to drug-induced increases in urinary glucose excretion and lowering of blood glucose, as shown in experiments with glucose clamping where SGLT2i-associated increases in plasma glucagon are prevented. However, regardless of the mechanisms involved, the current balance of evidence does not support that SGLT2 plays a crucial role for alpha-cell physiology or that SGLT2i-induced glucagon secretion is important for the associated increased EGP, particularly because the increase in EGP occurs before any rise in plasma glucagon.
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Affiliation(s)
- Rune E Kuhre
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Obesity Pharmacology, Novo Nordisk, Måløv, Denmark
| | - Carolyn F Deacon
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- School of Biomedical Sciences, Ulster University, Coleraine, UK
| | - Nicolai J Wewer Albrechtsen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Department of Clinical Biochemistry, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jens J Holst
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Novo Nordisk Foundation Centre for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Pancreatic Ppy-expressing γ-cells display mixed phenotypic traits and the adaptive plasticity to engage insulin production. Nat Commun 2021; 12:4458. [PMID: 34294685 PMCID: PMC8298494 DOI: 10.1038/s41467-021-24788-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 07/08/2021] [Indexed: 02/06/2023] Open
Abstract
The cellular identity of pancreatic polypeptide (Ppy)-expressing γ-cells, one of the rarest pancreatic islet cell-type, remains elusive. Within islets, glucagon and somatostatin, released respectively from α- and δ-cells, modulate the secretion of insulin by β-cells. Dysregulation of insulin production raises blood glucose levels, leading to diabetes onset. Here, we present the genetic signature of human and mouse γ-cells. Using different approaches, we identified a set of genes and pathways defining their functional identity. We found that the γ-cell population is heterogeneous, with subsets of cells producing another hormone in addition to Ppy. These bihormonal cells share identity markers typical of the other islet cell-types. In mice, Ppy gene inactivation or conditional γ-cell ablation did not alter glycemia nor body weight. Interestingly, upon β-cell injury induction, γ-cells exhibited gene expression changes and some of them engaged insulin production, like α- and δ-cells. In conclusion, we provide a comprehensive characterization of γ-cells and highlight their plasticity and therapeutic potential.
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Acreman S, Zhang Q. Regulation of α-cell glucagon secretion: The role of second messengers. Chronic Dis Transl Med 2021; 8:7-18. [PMID: 35620162 PMCID: PMC9128566 DOI: 10.1016/j.cdtm.2021.06.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 06/15/2021] [Indexed: 11/30/2022] Open
Abstract
Glucagon is a potent glucose‐elevating hormone that is secreted by pancreatic α‐cells. While well‐controlled glucagon secretion plays an important role in maintaining systemic glucose homeostasis and preventing hypoglycaemia, it is increasingly apparent that defects in the regulation of glucagon secretion contribute to impaired counter‐regulation and hyperglycaemia in diabetes. It has therefore been proposed that pharmacological interventions targeting glucagon secretion/signalling can have great potential in improving glycaemic control of patients with diabetes. However, despite decades of research, a consensus on the precise mechanisms of glucose regulation of glucagon secretion is yet to be reached. Second messengers are a group of small intracellular molecules that relay extracellular signals to the intracellular signalling cascade, modulating cellular functions. There is a growing body of evidence that second messengers, such as cAMP and Ca2+, play critical roles in α‐cell glucose‐sensing and glucagon secretion. In this review, we discuss the impact of second messengers on α‐cell electrical activity, intracellular Ca2+ dynamics and cell exocytosis. We highlight the possibility that the interaction between different second messengers may play a key role in the glucose‐regulation of glucagon secretion.
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Sanchez PKM, Khazaei M, Gatineau E, Geravandi S, Lupse B, Liu H, Dringen R, Wojtusciszyn A, Gilon P, Maedler K, Ardestani A. LDHA is enriched in human islet alpha cells and upregulated in type 2 diabetes. Biochem Biophys Res Commun 2021; 568:158-166. [PMID: 34217973 DOI: 10.1016/j.bbrc.2021.06.065] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Accepted: 06/20/2021] [Indexed: 12/25/2022]
Abstract
The lactate dehydrogenase isoform A (LDHA) is a key metabolic enzyme that preferentially catalyzes the conversion of pyruvate to lactate. Whereas LDHA is highly expressed in many tissues, its expression is turned off in the differentiated adult β-cell within the pancreatic islets. The repression of LDHA under normal physiological condition and its inappropriate upregulation under a diabetogenic environment is well-documented in rodent islets/β-cells but little is known about LDHA expression in human islet cells and whether its abundance is altered under diabetic conditions. Analysis of public single-cell RNA-seq (sc-RNA seq) data as well as cell type-specific immunolabeling of human pancreatic islets showed that LDHA was mainly localized in human α-cells while it is expressed at a very low level in β-cells. Furthermore, LDHA, both at mRNA and protein, as well as lactate production is upregulated in human pancreatic islets exposed to chronic high glucose treatment. Microscopic analysis of stressed human islets and autopsy pancreases from individuals with type 2 diabetes (T2D) showed LDHA upregulation mainly in human α-cells. Pharmacological inhibition of LDHA in isolated human islets enhanced insulin secretion under physiological conditions but did not significantly correct the deregulated secretion of insulin or glucagon under diabetic conditions.
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Affiliation(s)
| | - Mona Khazaei
- Centre for Biomolecular Interactions Bremen, University of Bremen, Bremen, Germany
| | - Eva Gatineau
- Pole of Endocrinology, Diabetes, and Nutrition (EDIN), Institute of Experimental and Clinical Research (IREC), Université Catholique de Louvain (UCLouvain), 1200, Brussels, Belgium
| | - Shirin Geravandi
- Centre for Biomolecular Interactions Bremen, University of Bremen, Bremen, Germany
| | - Blaz Lupse
- Centre for Biomolecular Interactions Bremen, University of Bremen, Bremen, Germany
| | - Huan Liu
- Centre for Biomolecular Interactions Bremen, University of Bremen, Bremen, Germany
| | - Ralf Dringen
- Centre for Biomolecular Interactions Bremen, University of Bremen, Bremen, Germany
| | - Anne Wojtusciszyn
- Department of Endocrinology, Diabetology and Metabolism, Lausanne University Hospital, Lausanne, Switzerland
| | - Patrick Gilon
- Pole of Endocrinology, Diabetes, and Nutrition (EDIN), Institute of Experimental and Clinical Research (IREC), Université Catholique de Louvain (UCLouvain), 1200, Brussels, Belgium
| | - Kathrin Maedler
- Centre for Biomolecular Interactions Bremen, University of Bremen, Bremen, Germany.
| | - Amin Ardestani
- Centre for Biomolecular Interactions Bremen, University of Bremen, Bremen, Germany; Department of Molecular Medicine, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran.
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Satin LS, Soleimanpour SA, Walker EM. New Aspects of Diabetes Research and Therapeutic Development. Pharmacol Rev 2021; 73:1001-1015. [PMID: 34193595 DOI: 10.1124/pharmrev.120.000160] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Both type 1 and type 2 diabetes mellitus are advancing at exponential rates, placing significant burdens on health care networks worldwide. Although traditional pharmacologic therapies such as insulin and oral antidiabetic stalwarts like metformin and the sulfonylureas continue to be used, newer drugs are now on the market targeting novel blood glucose-lowering pathways. Furthermore, exciting new developments in the understanding of beta cell and islet biology are driving the potential for treatments targeting incretin action, islet transplantation with new methods for immunologic protection, and the generation of functional beta cells from stem cells. Here we discuss the mechanistic details underlying past, present, and future diabetes therapies and evaluate their potential to treat and possibly reverse type 1 and 2 diabetes in humans. SIGNIFICANCE STATEMENT: Diabetes mellitus has reached epidemic proportions in the developed and developing world alike. As the last several years have seen many new developments in the field, a new and up to date review of these advances and their careful evaluation will help both clinical and research diabetologists to better understand where the field is currently heading.
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Affiliation(s)
- Leslie S Satin
- Department of Pharmacology (L.S.S.), Division of Metabolism, Endocrinology, and Diabetes, Department of Internal Medicine (L.S.S., S.A.S., E.M.W.), and Brehm Diabetes Center (L.S.S., S.A.S., E.M.W.), University of Michigan Medical School, Ann Arbor, Michigan; and VA Ann Arbor Healthcare System, Ann Arbor, Michigan (S.A.S.) ; ;
| | - Scott A Soleimanpour
- Department of Pharmacology (L.S.S.), Division of Metabolism, Endocrinology, and Diabetes, Department of Internal Medicine (L.S.S., S.A.S., E.M.W.), and Brehm Diabetes Center (L.S.S., S.A.S., E.M.W.), University of Michigan Medical School, Ann Arbor, Michigan; and VA Ann Arbor Healthcare System, Ann Arbor, Michigan (S.A.S.)
| | - Emily M Walker
- Department of Pharmacology (L.S.S.), Division of Metabolism, Endocrinology, and Diabetes, Department of Internal Medicine (L.S.S., S.A.S., E.M.W.), and Brehm Diabetes Center (L.S.S., S.A.S., E.M.W.), University of Michigan Medical School, Ann Arbor, Michigan; and VA Ann Arbor Healthcare System, Ann Arbor, Michigan (S.A.S.) ; ;
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Pancreatic β Cells Inhibit Glucagon Secretion from α Cells: An In Vitro Demonstration of α-β Cell Interaction. Nutrients 2021; 13:nu13072281. [PMID: 34209449 PMCID: PMC8308288 DOI: 10.3390/nu13072281] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 06/25/2021] [Accepted: 06/27/2021] [Indexed: 12/24/2022] Open
Abstract
Interactions between endocrine α and β cells are critical to their secretory function in vivo. The interactions are highly regulated, although yet to be fully understood. In this study, we aim to assess the impact of α and β cell co-culture on hormone secretion. Mouse clonal cell lines α-TC6-1 (α cell line) and MIN-6 (β cell line) were cultured independently or in combination in a medium containing 5.5, 11.1, or 25 mM glucose, respectively. After 72 h, hormone release was measured using insulin and glucagon secretion assays, the cell distribution was visualized by inverted microscopy and an immunocytochemistry assay, and changes in gene expressions were assessed using the RT-PCR technique. The co-culture of the two cell lines caused a decrease in glucagon secretion from α-TC1-6 cells, while no effect on insulin secretion from MIN-6 cells was revealed. Both types of cells were randomly scattered throughout the culture flask, unlike in mice islets in vivo where β cells cluster in the core and α cells are localized at the periphery. During the α-β cell co-culture, the gene expression of glucagon (Gcg) decreased significantly. We conclude that islet β cells suppress glucagon secretion from α cells, apparently via direct cell-to-cell contact, of which the molecular mechanism needs further verification.
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Singh B, Khattab F, Chae H, Desmet L, Herrera PL, Gilon P. K ATP channel blockers control glucagon secretion by distinct mechanisms: A direct stimulation of α-cells involving a [Ca 2+] c rise and an indirect inhibition mediated by somatostatin. Mol Metab 2021; 53:101268. [PMID: 34118477 PMCID: PMC8274344 DOI: 10.1016/j.molmet.2021.101268] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 05/10/2021] [Accepted: 06/03/2021] [Indexed: 02/06/2023] Open
Abstract
Objective Glucagon is secreted by pancreatic α-cells in response to hypoglycemia and its hyperglycemic effect helps to restore normal blood glucose. Insulin and somatostatin (SST) secretions from β- and δ-cells, respectively, are stimulated by glucose by mechanisms involving an inhibition of their ATP-sensitive K+ (KATP) channels, leading to an increase in [Ca2+]c that triggers exocytosis. Drugs that close KATP channels, such as sulfonylureas, are used to stimulate insulin release in type 2 diabetic patients. α-cells also express KATP channels. However, the mechanisms by which sulfonylureas control glucagon secretion are still largely debated and were addressed in the present study. In particular, we studied the effects of KATP channel blockers on α-cell [Ca2+]c and glucagon secretion in the presence of a low (1 mM) or a high (15 mM) glucose concentration and evaluated the role of SST in these effects. Methods Using a transgenic mouse model expressing the Ca2+-sensitive fluorescent protein, GCaMP6f, specifically in α-cells, we measured [Ca2+]c in α-cells either dispersed or within whole islets (by confocal microscopy). By measuring [Ca2+]c in α-cells within islets and glucagon secretion using the same perifusion protocols, we tested whether glucagon secretion correlated with changes in [Ca2+]c in response to sulfonylureas. We studied the role of SST in the effects of sulfonylureas using multiple approaches including genetic ablation of SST, or application of SST-14 and SST receptor antagonists. Results Application of the sulfonylureas, tolbutamide, or gliclazide, to a medium containing 1 mM or 15 mM glucose increased [Ca2+]c in α-cells by a direct effect as in β-cells. At low glucose, sulfonylureas inhibited glucagon secretion of islets despite the rise in α-cell [Ca2+]c that they triggered. This glucagonostatic effect was indirect and attributed to SST because, in the islets of SST-knockout mice, sulfonylureas induced a stimulation of glucagon secretion which correlated with an increase in α-cell [Ca2+]c. Experiments with exogenous SST-14 and SST receptor antagonists indicated that the glucagonostatic effect of sulfonylureas mainly resulted from an inhibition of the efficacy of cytosolic Ca2+ on exocytosis. Although SST-14 was also able to inhibit glucagon secretion by decreasing α-cell [Ca2+]c, no decrease in [Ca2+]c occurred during sulfonylurea application because it was largely counterbalanced by the direct stimulatory effect of these drugs on α-cell [Ca2+]c. At high glucose, i.e., in conditions where glucagon release was already low, sulfonylureas stimulated glucagon secretion because their direct stimulatory effect on α-cells exceeded the indirect effect by SST. Our results also indicated that, unexpectedly, SST-14 poorly decreased the efficacy of Ca2+ on exocytosis in β-cells. Conclusions Sulfonylureas exert two opposite actions on α-cells: a direct stimulation as in β-cells and an indirect inhibition by SST. This suggests that any alteration of SST paracrine influence, as described in diabetes, will modify the effect of sulfonylureas on glucagon release. In addition, we suggest that δ-cells inhibit α-cells more efficiently than β-cells. KATP channel blockers control glucagon secretion by two mechanisms. The first one is the direct stimulation of α-cell by a [Ca2+]c rise, as in β-cells. The second one is an indirect inhibition mediated by δ-cells releasing somatostatin. Somatostatin mainly reduces the efficacy of Ca2+ on exocytosis in α-cells. Somatostatin more potently inhibits glucagon than insulin secretion.
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Affiliation(s)
- Bilal Singh
- Université Catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle d'Endocrinologie, Diabète et Nutrition, Brussels, Belgium
| | - Firas Khattab
- Université Catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle d'Endocrinologie, Diabète et Nutrition, Brussels, Belgium
| | - Heeyoung Chae
- Université Catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle d'Endocrinologie, Diabète et Nutrition, Brussels, Belgium
| | - Lieven Desmet
- Université Catholique de Louvain, SMCS, Louvain Institute of Data Analysis and Modeling in economics and statistics, Louvain-la-Neuve, Belgium
| | - Pedro L Herrera
- Department of Genetic Medicine and Development, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Patrick Gilon
- Université Catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle d'Endocrinologie, Diabète et Nutrition, Brussels, Belgium.
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Zhu X, Lin C, Li L, Hu S, Cai X, Ji L. SGLT2i increased the plasma fasting glucagon level in patients with diabetes: A meta-analysis. Eur J Pharmacol 2021; 903:174145. [PMID: 33957085 DOI: 10.1016/j.ejphar.2021.174145] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2020] [Revised: 04/11/2021] [Accepted: 04/28/2021] [Indexed: 02/06/2023]
Abstract
Increased glucagon level was hypothesized to participate in the ketoacidosis associated with sodium-glucose co-transporter 2 inhibitors (SGLT2i) treatment. However, the effect of SGLT2i on glucagon remains controversial. Hence, we conducted this meta-analysis to assess the overall effect of SGLT2i treatment on plasma fasting glucagon level in patients with diabetes. PubMed/MEDLINE, Embase, and Cochrane databases were searched for studies published before August 2020. Clinical trials in patients with type 1 diabetes mellitus and type 2 diabetes mellitus with reports of glucagon changes before and after SGLT2i intervention were included. Eligible trials were analyzed by fixed-effect model, random effect model, and meta-regression analysis accordingly. In total, ten trials were included in this meta-analysis. Compared with the non-SGLT2i treatment group, SGLT2i treatment resulted in increased plasma fasting glucagon levels with significance (WMD, 8.35 pg/ml; 95% CI, 2.17-14.54 pg/ml, P<0.01) in patients with diabetes mellitus. Besides, when compared with non-SGLT2i control group, the insulin level decreased (WMD, -2.78 μU/ml; 95% CI, -5.11 to -0.46 μU/ml, P = 0.02) and ketone body level increased (WMD, 0.17 mmol/l; 95% CI, 0.09-0.25 mmol/l, P<0.01) in patients with type 2 diabetes. In conclusion, our result indicated SGLT2i intervention would increase the plasma fasting glucagon level in patients with diabetes mellitus. The increase in plasma fasting glucagon level may be associated with reduced insulin level. The increased glucagon-insulin ratio after the use of SGLT2i may make diabetic patients susceptible to ketosis.
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Affiliation(s)
- Xingyun Zhu
- Department of Endocrinology and Metabolism, Peking University People's Hospital, Beijing, China.
| | - Chu Lin
- Department of Endocrinology and Metabolism, Peking University People's Hospital, Beijing, China.
| | - Li Li
- Department of Endocrinology and Metabolism, Peking University People's Hospital, Beijing, China.
| | - Suiyuan Hu
- Department of Endocrinology and Metabolism, Peking University People's Hospital, Beijing, China.
| | - Xiaoling Cai
- Department of Endocrinology and Metabolism, Peking University People's Hospital, Beijing, China.
| | - Linong Ji
- Department of Endocrinology and Metabolism, Peking University People's Hospital, Beijing, China.
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Takatani T, Shirakawa J, Shibue K, Gupta MK, Kim H, Lu S, Hu J, White MF, Kennedy RT, Kulkarni RN. Insulin receptor substrate 1, but not IRS2, plays a dominant role in regulating pancreatic alpha cell function in mice. J Biol Chem 2021; 296:100646. [PMID: 33839150 PMCID: PMC8131928 DOI: 10.1016/j.jbc.2021.100646] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 03/24/2021] [Accepted: 04/07/2021] [Indexed: 11/29/2022] Open
Abstract
Dysregulated glucagon secretion deteriorates glycemic control in type 1 and type 2 diabetes. Although insulin is known to regulate glucagon secretion via its cognate receptor (insulin receptor, INSR) in pancreatic alpha cells, the role of downstream proteins and signaling pathways underlying insulin's activities are not fully defined. Using in vivo (knockout) and in vitro (knockdown) studies targeting insulin receptor substrate (IRS) proteins, we compared the relative roles of IRS1 and IRS2 in regulating alpha cell function. Alpha cell-specific IRS1-knockout mice exhibited glucose intolerance and inappropriate glucagon suppression during glucose tolerance tests. In contrast, alpha cell-specific IRS2-knockout animals manifested normal glucose tolerance and suppression of glucagon secretion after glucose administration. Alpha cell lines with stable IRS1 knockdown could not repress glucagon mRNA expression and exhibited a reduction in phosphorylation of AKT Ser/Thr kinase (AKT, at Ser-473 and Thr-308). AlphaIRS1KD cells also displayed suppressed global protein translation, including reduced glucagon expression, impaired cytoplasmic Ca2+ response, and mitochondrial dysfunction. This was supported by the identification of novel IRS1-specific downstream target genes, Trpc3 and Cartpt, that are associated with glucagon regulation in alpha cells. These results provide evidence that IRS1, rather than IRS2, is a dominant regulator of pancreatic alpha cell function.
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Affiliation(s)
- Tomozumi Takatani
- Islet Cell and Regenerative Biology, Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA; Department of Pediatrics, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Jun Shirakawa
- Laboratory of Diabetes and Metabolic Disorders, Institute for Molecular and Cellular Regulation (IMCR), Gunma University, Gunma, Japan
| | - Kimitaka Shibue
- Islet Cell and Regenerative Biology, Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Manoj K Gupta
- Islet Cell and Regenerative Biology, Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA; Cell Therapy Translational Engine (CTTE), Takeda Pharmaceuticals, Cambridge, Massachusetts, USA
| | - Hyunki Kim
- Islet Cell and Regenerative Biology, Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Shusheng Lu
- Departments of Chemistry and Pharmacology, University of Michigan, Ann Arbor, Michigan, USA
| | - Jiang Hu
- Islet Cell and Regenerative Biology, Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Morris F White
- Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Robert T Kennedy
- Departments of Chemistry and Pharmacology, University of Michigan, Ann Arbor, Michigan, USA
| | - Rohit N Kulkarni
- Islet Cell and Regenerative Biology, Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA; Harvard Stem Cell Institute, Harvard Medical School, Boston, Massachusetts, USA.
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Lewis GF, Carpentier AC, Pereira S, Hahn M, Giacca A. Direct and indirect control of hepatic glucose production by insulin. Cell Metab 2021; 33:709-720. [PMID: 33765416 DOI: 10.1016/j.cmet.2021.03.007] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 02/23/2021] [Accepted: 03/05/2021] [Indexed: 01/08/2023]
Abstract
There is general agreement that the acute suppression of hepatic glucose production by insulin is mediated by both a direct and an indirect effect on the liver. There is, however, no consensus regarding the relative magnitude of these effects under physiological conditions. Extensive research over the past three decades in humans and animal models has provided discordant results between these two modes of insulin action. Here, we review the field to make the case that physiologically direct hepatic insulin action dominates acute suppression of glucose production, but that there is also a delayed, second order regulation of this process via extrahepatic effects. We further provide our views regarding the timing, dominance, and physiological relevance of these effects and discuss novel concepts regarding insulin regulation of adipose tissue fatty acid metabolism and central nervous system (CNS) signaling to the liver, as regulators of insulin's extrahepatic effects on glucose production.
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Affiliation(s)
- Gary F Lewis
- Departments of Medicine and Physiology, University of Toronto, Toronto, ON, Canada; Banting & Best Diabetes Centre, University of Toronto, Toronto, ON, Canada; Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada.
| | - Andre C Carpentier
- Division of Endocrinology, Department of Medicine, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Sandra Pereira
- Centre for Addiction and Mental Health and Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Margaret Hahn
- Banting & Best Diabetes Centre, University of Toronto, Toronto, ON, Canada; Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada; Centre for Addiction and Mental Health and Department of Psychiatry, University of Toronto, Toronto, ON, Canada
| | - Adria Giacca
- Departments of Medicine and Physiology, University of Toronto, Toronto, ON, Canada; Banting & Best Diabetes Centre, University of Toronto, Toronto, ON, Canada; Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada
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Abstract
Glucagon-Like Peptide-1 (GLP-1) is an important peptide hormone secreted by L-cells in the gastrointestinal tract in response to nutrients. It is produced by the differential cleavage of the proglucagon peptide. GLP-1 elicits a wide variety of physiological responses in many tissues that contribute to metabolic homeostasis. For these reasons, therapies designed to either increase endogenous GLP-1 levels or introduce exogenous peptide mimetics are now widely used in the management of diabetes. In addition to GLP-1 production from L-cells, recent reports suggest that pancreatic islet alpha cells may also synthesize and secrete GLP-1. Intra-islet GLP-1 may therefore play an unappreciated role in islet health and glucose regulation, suggesting a potential functional paracrine role for islet-derived GLP-1. In this review, we assess the current literature from an islet-centric point-of-view to better understand the production, degradation, and actions of GLP-1 within the endocrine pancreas in rodents and humans. The relevance of intra-islet GLP-1 in human physiology is discussed regarding the potential role of intra-islet GLP-1 in islet health and dysfunction.
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Affiliation(s)
- Scott A. Campbell
- Department of Medicine, Faculty of Medicine, Université de Montréal, Montreal Diabetes Research Centre CRCHUM, Montréal, Canada
| | - Janyne Johnson
- Alberta Diabetes Institute, Department of Pharmacology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada
| | - Peter E. Light
- Alberta Diabetes Institute, Department of Pharmacology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada
- CONTACT Peter E. Light Alberta Diabetes Institute, Department of Pharmacology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AlbertaT6G 2E1, Canada
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Ghislain J, Poitout V. Targeting lipid GPCRs to treat type 2 diabetes mellitus - progress and challenges. Nat Rev Endocrinol 2021; 17:162-175. [PMID: 33495605 DOI: 10.1038/s41574-020-00459-w] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/04/2020] [Indexed: 02/07/2023]
Abstract
Therapeutic approaches to the treatment of type 2 diabetes mellitus that are designed to increase insulin secretion either directly target β-cells or indirectly target gastrointestinal enteroendocrine cells (EECs), which release hormones that modulate insulin secretion (for example, incretins). Given that β-cells and EECs both express a large array of G protein-coupled receptors (GPCRs) that modulate insulin secretion, considerable research and development efforts have been undertaken to design therapeutic drugs targeting these GPCRs. Among them are GPCRs specific for free fatty acid ligands (lipid GPCRs), including free fatty acid receptor 1 (FFA1, otherwise known as GPR40), FFA2 (GPR43), FFA3 (GPR41) and FFA4 (GPR120), as well as the lipid metabolite binding glucose-dependent insulinotropic receptor (GPR119). These lipid GPCRs have demonstrated important roles in the control of islet and gut hormone secretion. Advances in lipid GPCR pharmacology have led to the identification of a number of synthetic agonists that exert beneficial effects on glucose homeostasis in preclinical studies. Yet, translation of these promising results to the clinic has so far been disappointing. In this Review, we present the physiological roles, pharmacology and clinical studies of these lipid receptors and discuss the challenges associated with their clinical development for the treatment of type 2 diabetes mellitus.
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Affiliation(s)
- Julien Ghislain
- Montreal Diabetes Research Center, Centre Hospitalier de l'Université de Montréal, Montréal, QC, Canada
| | - Vincent Poitout
- Montreal Diabetes Research Center, Centre Hospitalier de l'Université de Montréal, Montréal, QC, Canada.
- Department of Medicine, Université de Montréal, Montréal, QC, Canada.
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Gao R, Yang T, Zhang Q. δ-Cells: The Neighborhood Watch in the Islet Community. BIOLOGY 2021; 10:biology10020074. [PMID: 33494193 PMCID: PMC7909827 DOI: 10.3390/biology10020074] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 01/19/2021] [Accepted: 01/19/2021] [Indexed: 12/29/2022]
Abstract
Somatostatin-secreting δ-cells have aroused great attention due to their powerful roles in coordination of islet insulin and glucagon secretion and maintenance of glucose homeostasis. δ-cells exhibit neuron-like morphology with projections which enable pan-islet somatostatin paracrine regulation despite their scarcity in the islets. The expression of a range of hormone and neurotransmitter receptors allows δ-cells to integrate paracrine, endocrine, neural and nutritional inputs, and provide rapid and precise feedback modulations on glucagon and insulin secretion from α- and β-cells, respectively. Interestingly, the paracrine tone of δ-cells can be effectively modified in response to factors released by neighboring cells in this interactive communication, such as insulin, urocortin 3 and γ-aminobutyric acid from β-cells, glucagon, glutamate and glucagon-like peptide-1 from α-cells. In the setting of diabetes, defects in δ-cell function lead to suboptimal insulin and glucagon outputs and lift the glycemic set-point. The interaction of δ-cells and non-δ-cells also becomes defective in diabetes, with reduces paracrine feedback to β-cells to exacerbate hyperglycemia or enhanced inhibition of α-cells, disabling counter-regulation, to cause hypoglycemia. Thus, it is possible to restore/optimize islet function in diabetes targeting somatostatin signaling, which could open novel avenues for the development of effective diabetic treatments.
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Affiliation(s)
- Rui Gao
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 7LE, UK;
- Department of Endocrinology and Metabolism, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China;
| | - Tao Yang
- Department of Endocrinology and Metabolism, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China;
| | - Quan Zhang
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 7LE, UK;
- Correspondence:
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Campbell JE, Newgard CB. Mechanisms controlling pancreatic islet cell function in insulin secretion. Nat Rev Mol Cell Biol 2021; 22:142-158. [PMID: 33398164 DOI: 10.1038/s41580-020-00317-7] [Citation(s) in RCA: 247] [Impact Index Per Article: 82.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/19/2020] [Indexed: 02/07/2023]
Abstract
Metabolic homeostasis in mammals is tightly regulated by the complementary actions of insulin and glucagon. The secretion of these hormones from pancreatic β-cells and α-cells, respectively, is controlled by metabolic, endocrine, and paracrine regulatory mechanisms and is essential for the control of blood levels of glucose. The deregulation of these mechanisms leads to various pathologies, most notably type 2 diabetes, which is driven by the combined lesions of impaired insulin action and a loss of the normal insulin secretion response to glucose. Glucose stimulates insulin secretion from β-cells in a bi-modal fashion, and new insights about the underlying mechanisms, particularly relating to the second or amplifying phase of this secretory response, have been recently gained. Other recent work highlights the importance of α-cell-produced proglucagon-derived peptides, incretin hormones from the gastrointestinal tract and other dietary components, including certain amino acids and fatty acids, in priming and potentiation of the β-cell glucose response. These advances provide a new perspective for the understanding of the β-cell failure that triggers type 2 diabetes.
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Affiliation(s)
- Jonathan E Campbell
- Sarah W. Stedman Nutrition and Metabolism Center and Duke Molecular Physiology Institute, Duke University Medical Center, Durham, NC, USA.,Department of Medicine, Endocrinology and Metabolism Division, Duke University Medical Center, Durham, NC, USA.,Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC, USA
| | - Christopher B Newgard
- Sarah W. Stedman Nutrition and Metabolism Center and Duke Molecular Physiology Institute, Duke University Medical Center, Durham, NC, USA. .,Department of Medicine, Endocrinology and Metabolism Division, Duke University Medical Center, Durham, NC, USA. .,Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC, USA.
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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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Svendsen B, Holst JJ. Paracrine regulation of somatostatin secretion by insulin and glucagon in mouse pancreatic islets. Diabetologia 2021; 64:142-151. [PMID: 33043402 DOI: 10.1007/s00125-020-05288-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 07/26/2020] [Indexed: 01/11/2023]
Abstract
AIMS/HYPOTHESIS The endocrine pancreas comprises the islets of Langerhans, primarily consisting of beta cells, alpha cells and delta cells responsible for secretion of insulin, glucagon and somatostatin, respectively. A certain level of intra-islet communication is thought to exist, where the individual hormones may reach the other islet cells and regulate their secretion. Glucagon has been demonstrated to importantly regulate insulin secretion, while somatostatin powerfully inhibits both insulin and glucagon secretion. In this study we investigated how secretion of somatostatin is regulated by paracrine signalling from glucagon and insulin. METHODS Somatostatin secretion was measured from perfused mouse pancreases isolated from wild-type as well as diphtheria toxin-induced alpha cell knockdown, and global glucagon receptor knockout (Gcgr-/-) mice. We studied the effects of varying glucose concentrations together with infusions of arginine, glucagon, insulin and somatostatin, as well as infusions of antagonists of insulin, somatostatin and glucagon-like peptide 1 (GLP-1) receptors. RESULTS A tonic inhibitory role of somatostatin was demonstrated with infusion of somatostatin receptor antagonists, which significantly increased glucagon secretion at low and high glucose, whereas insulin secretion was only increased at high glucose levels. Infusion of glucagon dose-dependently increased somatostatin secretion approximately twofold in control mice. Exogenous glucagon had no effect on somatostatin secretion in Gcgr-/- mice, and a reduced effect when combined with the GLP-1 receptor antagonist exendin 9-39. Diphtheria toxin-induced knockdown of glucagon producing cells led to reduced somatostatin secretion in response to 12 mmol/l glucose and arginine infusions. In Gcgr-/- mice (where glucagon levels are dramatically increased) overall somatostatin secretion was increased. However, infusion of exendin 9-39 in Gcgr-/- mice completely abolished somatostatin secretion in response to glucose and arginine. Neither insulin nor an insulin receptor antagonist (S961) had any effect on somatostatin secretion. CONCLUSIONS/INTERPRETATION Our findings demonstrate that somatostatin and glucagon secretion are linked in a reciprocal feedback cycle with somatostatin inhibiting glucagon secretion at low and high glucose levels, and glucagon stimulating somatostatin secretion via the glucagon and GLP-1 receptors. Graphical abstract.
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Affiliation(s)
- Berit Svendsen
- NovoNordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
| | - Jens J Holst
- NovoNordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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Wang B, Yang Y, Yuan H, Li X. Association between Neutrophilic Granulocyte Percentage and Diabetes Mellitus in Cushing's Syndrome Patients: A Cross-Sectional Study. Int J Endocrinol 2021; 2021:9536730. [PMID: 34880914 PMCID: PMC8648481 DOI: 10.1155/2021/9536730] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 11/08/2021] [Accepted: 11/18/2021] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Glucose metabolism is frequently impaired in patients with Cushing's syndrome (CS) due to chronic exposure to excess glucocorticoids. Inflammation plays an essential role in the pathophysiology of diabetes mellitus (DM). The present study aimed to investigate the potential associations of inflammatory blood cell parameters, including white blood cell (WBC) count, neutrophil count, neutrophilic granulocyte percentage (NEUT%), lymphocyte count (LYM), and lymphocyte proportion (LYM%), with diabetes mellitus in Cushing's syndrome patients. MATERIALS AND METHODS The cross-sectional study was conducted in Zhongshan Hospital of Fudan University, China. A total of 150 patients with Cushing's syndrome were retrospectively screened from 2017 to 2019. The demographic data, clinical data, and blood samples (lipids, adrenal, glucose, and inflammatory blood cell parameters) were recorded. Statistical analyses were carried out by using the SPSS software package, version 13.0. RESULTS In this study, the prevalence of diabetes mellitus was 38.7% in patients with Cushing's syndrome. Patients with DM had higher WBC, neutrophil, NEUT% levels than patients without DM (p < 0.05). As the NEUT% increased, a stepwise increase in glucose and glycated hemoglobin (HbA1c) level was observed. In addition, in the multivariate logistic regression, NEUT% was a significant independent risk factor for DM, regardless of gender, age, body mass index (BMI), and triglyceride and 12 midnight cortisol (12 MN cortisol) level (OR = 2.542, 95% CI 1.337-4.835, p < 0.001). CONCLUSIONS In conclusion, elevated NEUT% level was linked to diabetes in patients with Cushing's syndrome. The neutrophilic granulocyte percentage may be referred to as a new predictor for diabetes in Cushing's syndrome patients.
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Affiliation(s)
- Baomin Wang
- Department of Endocrinology and Metabolism, Zhongshan Hospital, Fudan University, Shanghai 200032, China
| | - Yumei Yang
- Department of Endocrinology and Metabolism, Zhongshan Hospital, Fudan University, Shanghai 200032, China
| | - Haoyue Yuan
- Department of Endocrinology and Metabolism, Zhongshan Hospital, Fudan University, Shanghai 200032, China
| | - Xiaomu Li
- Department of Endocrinology and Metabolism, Zhongshan Hospital, Fudan University, Shanghai 200032, China
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Shamsi BH, Chatoo M, Xu XK, Xu X, Chen XQ. Versatile Functions of Somatostatin and Somatostatin Receptors in the Gastrointestinal System. Front Endocrinol (Lausanne) 2021; 12:652363. [PMID: 33796080 PMCID: PMC8009181 DOI: 10.3389/fendo.2021.652363] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 02/19/2021] [Indexed: 01/03/2023] Open
Abstract
Somatostatin (SST) and somatostatin receptors (SSTRs) play an important role in the brain and gastrointestinal (GI) system. SST is produced in various organs and cells, and the inhibitory function of somatostatin-containing cells is involved in a range of physiological functions and pathological modifications. The GI system is the largest endocrine organ for digestion and absorption, SST-endocrine cells and neurons in the GI system are a critical effecter to maintain homeostasis via SSTRs 1-5 and co-receptors, while SST-SSTRs are involved in chemo-sensory, mucus, and hormone secretion, motility, inflammation response, itch, and pain via the autocrine, paracrine, endocrine, and exoendocrine pathways. It is also a power inhibitor for tumor cell proliferation, severe inflammation, and post-operation complications, and is a first-line anti-cancer drug in clinical practice. This mini review focuses on the current function of producing SST endocrine cells and local neurons SST-SSTRs in the GI system, discusses new development prognostic markers, phosphate-specific antibodies, and molecular imaging emerging in diagnostics and therapy, and summarizes the mechanism of the SST family in basic research and clinical practice. Understanding of endocrines and neuroendocrines in SST-SSTRs in GI will provide an insight into advanced medicine in basic and clinical research.
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Affiliation(s)
- Bilal Haider Shamsi
- Department of Neurobiology, Department of Neurology of the Second Affiliated Hospital, School of Brain Science and Brain Medicine, Hangzhou, China
| | - Mahanand Chatoo
- Department of Neurobiology, Department of Neurology of the Second Affiliated Hospital, School of Brain Science and Brain Medicine, Hangzhou, China
| | - Xiao Kang Xu
- Department of Neurobiology, Department of Neurology of the Second Affiliated Hospital, School of Brain Science and Brain Medicine, Hangzhou, China
| | - Xun Xu
- College of Renji, Wenzhou Medical University, Wenzhou, China
| | - Xue Qun Chen
- Department of Neurobiology, Department of Neurology of the Second Affiliated Hospital, School of Brain Science and Brain Medicine, Hangzhou, China
- National Health Commission (NHC) and Chinese Academy of Medical Sciences (CAMS) Key Laboratory of Medical Neurobiology, Ministry of Education (MOE), Frontier Science Center for Brain Research and Brain Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, China
- *Correspondence: Xue Qun Chen,
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73
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Morettini M, Burattini L, Göbl C, Pacini G, Ahrén B, Tura A. Mathematical Model of Glucagon Kinetics for the Assessment of Insulin-Mediated Glucagon Inhibition During an Oral Glucose Tolerance Test. Front Endocrinol (Lausanne) 2021; 12:611147. [PMID: 33828527 PMCID: PMC8020816 DOI: 10.3389/fendo.2021.611147] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 01/26/2021] [Indexed: 01/29/2023] Open
Abstract
Glucagon is secreted from the pancreatic alpha cells and plays an important role in the maintenance of glucose homeostasis, by interacting with insulin. The plasma glucose levels determine whether glucagon secretion or insulin secretion is activated or inhibited. Despite its relevance, some aspects of glucagon secretion and kinetics remain unclear. To gain insight into this, we aimed to develop a mathematical model of the glucagon kinetics during an oral glucose tolerance test, which is sufficiently simple to be used in the clinical practice. The proposed model included two first-order differential equations -one describing glucagon and the other describing C-peptide in a compartment remote from plasma - and yielded a parameter of possible clinical relevance (i.e., SGLUCA(t), glucagon-inhibition sensitivity to glucose-induced insulin secretion). Model was validated on mean glucagon data derived from the scientific literature, yielding values for SGLUCA(t) ranging from -15.03 to 2.75 (ng of glucagon·nmol of C-peptide-1). A further validation on a total of 100 virtual subjects provided reliable results (mean residuals between -1.5 and 1.5 ng·L-1) and a negative significant linear correlation (r = -0.74, p < 0.0001, 95% CI: -0.82 - -0.64) between SGLUCA(t) and the ratio between the areas under the curve of suprabasal remote C-peptide and glucagon. Model reliability was also proven by the ability to capture different patterns in glucagon kinetics. In conclusion, the proposed model reliably reproduces glucagon kinetics and is characterized by sufficient simplicity to be possibly used in the clinical practice, for the estimation in the single individual of some glucagon-related parameters.
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Affiliation(s)
- Micaela Morettini
- Department of Information Engineering, Università Politecnica delle Marche, Ancona, Italy
- *Correspondence: Micaela Morettini,
| | - Laura Burattini
- Department of Information Engineering, Università Politecnica delle Marche, Ancona, Italy
| | - Christian Göbl
- Division of Obstetrics and Feto-Maternal Medicine, Department of Obstetrics and Gynecology, Medical University of Vienna, Vienna, Austria
| | - Giovanni Pacini
- Metabolic Unit, CNR Institute of Neuroscience, Padova, Italy
| | - Bo Ahrén
- Department of Clinical Sciences, Faculty of Medicine, Lund University, Lund, Sweden
| | - Andrea Tura
- Metabolic Unit, CNR Institute of Neuroscience, Padova, Italy
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74
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Grubelnik V, Zmazek J, Markovič R, Gosak M, Marhl M. Mitochondrial Dysfunction in Pancreatic Alpha and Beta Cells Associated with Type 2 Diabetes Mellitus. Life (Basel) 2020; 10:E348. [PMID: 33327428 PMCID: PMC7764865 DOI: 10.3390/life10120348] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 12/04/2020] [Accepted: 12/10/2020] [Indexed: 12/16/2022] Open
Abstract
Type 2 diabetes mellitus is a complex multifactorial disease of epidemic proportions. It involves genetic and lifestyle factors that lead to dysregulations in hormone secretion and metabolic homeostasis. Accumulating evidence indicates that altered mitochondrial structure, function, and particularly bioenergetics of cells in different tissues have a central role in the pathogenesis of type 2 diabetes mellitus. In the present study, we explore how mitochondrial dysfunction impairs the coupling between metabolism and exocytosis in the pancreatic alpha and beta cells. We demonstrate that reduced mitochondrial ATP production is linked with the observed defects in insulin and glucagon secretion by utilizing computational modeling approach. Specifically, a 30-40% reduction in alpha cells' mitochondrial function leads to a pathological shift of glucagon secretion, characterized by oversecretion at high glucose concentrations and insufficient secretion in hypoglycemia. In beta cells, the impaired mitochondrial energy metabolism is accompanied by reduced insulin secretion at all glucose levels, but the differences, compared to a normal beta cell, are the most pronounced in hyperglycemia. These findings improve our understanding of metabolic pathways and mitochondrial bioenergetics in the pathology of type 2 diabetes mellitus and might help drive the development of innovative therapies to treat various metabolic diseases.
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Affiliation(s)
- Vladimir Grubelnik
- Faculty of Electrical Engineering and Computer Science, University of Maribor, SI-2000 Maribor, Slovenia; (V.G.); (R.M.)
| | - Jan Zmazek
- Faculty of Natural Sciences and Mathematics, University of Maribor, SI-2000 Maribor, Slovenia; (J.Z.); (M.G.)
| | - Rene Markovič
- Faculty of Electrical Engineering and Computer Science, University of Maribor, SI-2000 Maribor, Slovenia; (V.G.); (R.M.)
- Faculty of Natural Sciences and Mathematics, University of Maribor, SI-2000 Maribor, Slovenia; (J.Z.); (M.G.)
| | - Marko Gosak
- Faculty of Natural Sciences and Mathematics, University of Maribor, SI-2000 Maribor, Slovenia; (J.Z.); (M.G.)
- Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia
| | - Marko Marhl
- Faculty of Natural Sciences and Mathematics, University of Maribor, SI-2000 Maribor, Slovenia; (J.Z.); (M.G.)
- Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia
- Faculty of Education, University of Maribor, SI-2000 Maribor, Slovenia
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75
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Haris B, Saraswathi S, Hussain K. Somatostatin analogues for the treatment of hyperinsulinaemic hypoglycaemia. Ther Adv Endocrinol Metab 2020; 11:2042018820965068. [PMID: 33329885 PMCID: PMC7720331 DOI: 10.1177/2042018820965068] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 09/11/2020] [Indexed: 01/10/2023] Open
Abstract
Hyperinsulinaemic hypoglycaemia (HH) is a biochemical finding of low blood glucose levels due to the dysregulation of insulin secretion from pancreatic β-cells. Under normal physiological conditions, glucose metabolism is coupled to β-cell insulin secretion so that blood glucose levels are maintained within the physiological range of 3.5-5.5 mmol/L. However, in HH this coupling of glucose metabolism to insulin secretion is perturbed so that insulin secretion becomes unregulated. HH typically occurs in the neonatal, infancy and childhood periods and can be due to many different causes. Adults can also present with HH but the causes in adults tend to be different. Somatostatin (SST) is a peptide hormone that is released by the delta cells (δ-cells) in the pancreas. It binds to G protein-coupled SST receptors to regulate a variety of location-specific and selective functions such as hormone inhibition, neurotransmission and cell proliferation. SST plays a potent role in the regulation of both insulin and glucagon secretion in response to changes in glucose levels by negative feedback mechanism. The half-life of SST is only 1-3 min due to quick degradation by peptidases in plasma and tissues. Thus, a direct continuous intravenous or subcutaneous infusion is required to achieve the therapeutic effect. These limitations prompted the discovery of SST analogues such as octreotide and lanreotide, which have longer half-lives and therefore can be administered as injections. SST analogues are used to treat different forms of HH in children and adults and therapeutic effect is achieved by suppressing insulin secretion from pancreatic β-cells by complex mechanisms. These treatments are associated with several side effects, especially in the newborn period, with necrotizing enterocolitis being the most serious side effect and hence SS analogues should be used with extreme caution in this age group.
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Affiliation(s)
- Basma Haris
- Department of Paediatric Medicine, Division of Endocrinology, Sidra Medicine, Doha, Qatar
| | - Saras Saraswathi
- Department of Paediatric Medicine, Division of Endocrinology, Sidra Medicine, Doha, Qatar
| | - Khalid Hussain
- Professor of Paediatrics, Weill Cornell Medicine-Qatar, Division Chief – Endocrinology, Department of Paediatric Medicine, Division of Endocrinology, Sidra Medicine, OPC, C6-340 |PO Box 26999, Al Luqta Street, Education City North Campus, Doha, Qatar
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76
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Gilor C, Duesberg C, Elliott DA, Feldman EC, Mundinger TO, Taborsky GJ, Nelson RW, Havel PJ. Co-impairment of autonomic and glucagon responses to insulin-induced hypoglycemia in dogs with naturally occurring insulin-dependent diabetes mellitus. Am J Physiol Endocrinol Metab 2020; 319:E1074-E1083. [PMID: 33044845 PMCID: PMC7792666 DOI: 10.1152/ajpendo.00379.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
This study aimed to investigate the contributions of two factors potentially impairing glucagon response to insulin-induced hypoglycemia (IIH) in insulin-deficient diabetes: 1) loss of paracrine disinhibition by intra-islet insulin and 2) defects in the activation of the autonomic inputs to the islet. Plasma glucagon responses during hyperinsulinemic-hypoglycemic clamps ([Formula: see text]40 mg/dL) were assessed in dogs with spontaneous diabetes (n = 13) and in healthy nondiabetic dogs (n = 6). Plasma C-peptide responses to intravenous glucagon were measured to assess endogenous insulin secretion. Plasma pancreatic polypeptide, epinephrine, and norepinephrine were measured as indices of parasympathetic and sympathoadrenal autonomic responses to IIH. In 8 of the 13 diabetic dogs, glucagon did not increase during IIH (diabetic nonresponder [DMN]; ∆ = -6 ± 12 pg/mL). In five other diabetic dogs (diabetic responder [DMR]), glucagon responses (∆ = +26 ± 12) were within the range of nondiabetic control dogs (∆ = +27 ± 16 pg/mL). C-peptide responses to intravenous glucagon were absent in diabetic dogs. Activation of all three autonomic responses were impaired in DMN dogs but remained intact in DMR dogs. Each of the three autonomic responses to IIH was positively correlated with glucagon responses across the three groups. The study conclusions are as follows: 1) Impairment of glucagon responses in DMN dogs is not due to generalized impairment of α-cell function. 2) Loss of tonic inhibition of glucagon secretion by insulin is not sufficient to produce loss of the glucagon response; impairment of autonomic activation is also required. 3) In dogs with major β-cell function loss, activation of the autonomic inputs is sufficient to mediate an intact glucagon response to IIH.NEW & NOTEWORTHY In dogs with naturally occurring, insulin-dependent (C-peptide negative) diabetes mellitus, impairment of glucagon responses is not due to generalized impairment of α-cell function. Loss of tonic inhibition of glucagon secretion by insulin is not sufficient, by itself, to produce loss of the glucagon response. Rather, impaired activation of the parasympathetic and sympathoadrenal autonomic inputs to the pancreas is also required. Activation of the autonomic inputs to the pancreas is sufficient to mediate an intact glucagon response to insulin-induced hypoglycemia in dogs with naturally occurring diabetes mellitus. These results have important implications that include leading to a greater understanding and insight into the pathophysiology, prevention, and treatment of hypoglycemia during insulin treatment of diabetes in companion dogs and in human patients.
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Affiliation(s)
- Chen Gilor
- Department of Veterinary Medicine and Epidemiology, University of California, Davis, California
- Department of Small Animal Clinical Sciences, University of Florida, Gainesville, Florida
| | - Cynthia Duesberg
- Department of Veterinary Medicine and Epidemiology, University of California, Davis, California
| | - Denise A Elliott
- Department of Veterinary Medicine and Epidemiology, University of California, Davis, California
| | - Edward C Feldman
- Department of Veterinary Medicine and Epidemiology, University of California, Davis, California
| | | | - Gerald J Taborsky
- Department of Medicine, University of Washington, Seattle, Washington
| | - Richard W Nelson
- Department of Veterinary Medicine and Epidemiology, University of California, Davis, California
| | - Peter J Havel
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California
- Department of Nutrition, School of Veterinary Medicine, University of California, Davis, California
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77
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Shikata M, Ashida K, Goto Y, Nagayama A, Iwata S, Yano M, Hasuzawa N, Hara K, Mawatari K, Sakata K, Tsuruta M, Wada N, Nomura M. Pasireotide-induced hyperglycemia in a patient with Cushing's disease: Potential use of sodium-glucose cotransporter 2 inhibitor and glucagon-like peptide-1 receptor agonist for treatment. Clin Case Rep 2020; 8:2613-2618. [PMID: 33363790 PMCID: PMC7752440 DOI: 10.1002/ccr3.3230] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2020] [Revised: 06/05/2020] [Accepted: 07/18/2020] [Indexed: 12/17/2022] Open
Abstract
Pasireotide improves hypercortisolemia and induces hyperglycemia via somatostatin receptor type-5 stimulation. GLP-1RA and SGLT2 inhibitor potentially help regulate hyperglycemia in patients with Cushing's disease, especially after pasireotide administration.
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Affiliation(s)
- Masato Shikata
- Division of Endocrinology and MetabolismDepartment of Internal MedicineKurume University School of MedicineFukuokaJapan
| | - Kenji Ashida
- Division of Endocrinology and MetabolismDepartment of Internal MedicineKurume University School of MedicineFukuokaJapan
| | - Yuka Goto
- Division of Endocrinology and MetabolismDepartment of Internal MedicineKurume University School of MedicineFukuokaJapan
| | - Ayako Nagayama
- Division of Endocrinology and MetabolismDepartment of Internal MedicineKurume University School of MedicineFukuokaJapan
| | - Shimpei Iwata
- Division of Endocrinology and MetabolismDepartment of Internal MedicineKurume University School of MedicineFukuokaJapan
| | - Mamiko Yano
- Division of Endocrinology and MetabolismDepartment of Internal MedicineKurume University School of MedicineFukuokaJapan
| | - Nao Hasuzawa
- Division of Endocrinology and MetabolismDepartment of Internal MedicineKurume University School of MedicineFukuokaJapan
| | - Kento Hara
- Division of Endocrinology and MetabolismDepartment of Internal MedicineKurume University School of MedicineFukuokaJapan
| | - Kazutoshi Mawatari
- Division of Cardiovascular MedicineDepartment of Internal MedicineKurume University School of MedicineFukuokaJapan
| | - Kiyohiko Sakata
- Department of NeurosurgeryKurume University School of MedicineFukuokaJapan
| | - Munehisa Tsuruta
- Division of Endocrinology and MetabolismDepartment of Internal MedicineKurume University School of MedicineFukuokaJapan
| | - Nobuhiko Wada
- Division of Endocrinology and MetabolismDepartment of Internal MedicineKurume University School of MedicineFukuokaJapan
| | - Masatoshi Nomura
- Division of Endocrinology and MetabolismDepartment of Internal MedicineKurume University School of MedicineFukuokaJapan
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78
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Chae H, Augustin R, Gatineau E, Mayoux E, Bensellam M, Antoine N, Khattab F, Lai BK, Brusa D, Stierstorfer B, Klein H, Singh B, Ruiz L, Pieper M, Mark M, Herrera PL, Gribble FM, Reimann F, Wojtusciszyn A, Broca C, Rita N, Piemonti L, Gilon P. SGLT2 is not expressed in pancreatic α- and β-cells, and its inhibition does not directly affect glucagon and insulin secretion in rodents and humans. Mol Metab 2020; 42:101071. [PMID: 32896668 PMCID: PMC7554656 DOI: 10.1016/j.molmet.2020.101071] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 08/13/2020] [Accepted: 08/25/2020] [Indexed: 12/22/2022] Open
Abstract
Objective Sodium-glucose cotransporter 2 (SGLT2) inhibitors (SGLT2i), or gliflozins, are anti-diabetic drugs that lower glycemia by promoting glucosuria, but they also stimulate endogenous glucose and ketone body production. The likely causes of these metabolic responses are increased blood glucagon levels, and decreased blood insulin levels, but the mechanisms involved are hotly debated. This study verified whether or not SGLT2i affect glucagon and insulin secretion by a direct action on islet cells in three species, using multiple approaches. Methods We tested the in vivo effects of two selective SGLT2i (dapagliflozin, empagliflozin) and a SGLT1/2i (sotagliflozin) on various biological parameters (glucosuria, glycemia, glucagonemia, insulinemia) in mice. mRNA expression of SGLT2 and other glucose transporters was assessed in rat, mouse, and human FACS-purified α- and β-cells, and by analysis of two human islet cell transcriptomic datasets. Immunodetection of SGLT2 in pancreatic tissues was performed with a validated antibody. The effects of dapagliflozin, empagliflozin, and sotagliflozin on glucagon and insulin secretion were assessed using isolated rat, mouse and human islets and the in situ perfused mouse pancreas. Finally, we tested the long-term effect of SGLT2i on glucagon gene expression. Results SGLT2 inhibition in mice increased the plasma glucagon/insulin ratio in the fasted state, an effect correlated with a decline in glycemia. Gene expression analyses and immunodetections showed no SGLT2 mRNA or protein expression in rodent and human islet cells, but moderate SGLT1 mRNA expression in human α-cells. However, functional experiments on rat, mouse, and human (29 donors) islets and the in situ perfused mouse pancreas did not identify any direct effect of dapagliflozin, empagliflozin or sotagliflozin on glucagon and insulin secretion. SGLT2i did not affect glucagon gene expression in rat and human islets. Conclusions The data indicate that the SGLT2i-induced increase of the plasma glucagon/insulin ratio in vivo does not result from a direct action of the gliflozins on islet cells. Gliflozins (SGLT2 and SGLT1/2 inhibitors) increase plasma glucagon/insulin ratio. SGLT2 is not expressed in rodent and human pancreatic α- and β-cells. SGLT1 is however expressed in human α-cells. SGLT2 and SGLT1/2 inhibitors do not directly affect glucagon and insulin secretion.
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Affiliation(s)
- Heeyoung Chae
- Pole of Endocrinology, Diabetes, and Nutrition (EDIN), Institute of Experimental and Clinical Research (IREC), Université Catholique de Louvain (UCLouvain), 1200, Brussels, Belgium
| | - Robert Augustin
- Department of Cardiometabolic Disease Research, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany
| | - Eva Gatineau
- Pole of Endocrinology, Diabetes, and Nutrition (EDIN), Institute of Experimental and Clinical Research (IREC), Université Catholique de Louvain (UCLouvain), 1200, Brussels, Belgium
| | - Eric Mayoux
- Department of Cardiometabolic Disease Research, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany
| | - Mohammed Bensellam
- Pole of Endocrinology, Diabetes, and Nutrition (EDIN), Institute of Experimental and Clinical Research (IREC), Université Catholique de Louvain (UCLouvain), 1200, Brussels, Belgium
| | - Nancy Antoine
- Pole of Endocrinology, Diabetes, and Nutrition (EDIN), Institute of Experimental and Clinical Research (IREC), Université Catholique de Louvain (UCLouvain), 1200, Brussels, Belgium
| | - Firas Khattab
- Pole of Endocrinology, Diabetes, and Nutrition (EDIN), Institute of Experimental and Clinical Research (IREC), Université Catholique de Louvain (UCLouvain), 1200, Brussels, Belgium
| | - Bao-Khanh Lai
- Pole of Endocrinology, Diabetes, and Nutrition (EDIN), Institute of Experimental and Clinical Research (IREC), Université Catholique de Louvain (UCLouvain), 1200, Brussels, Belgium
| | - Davide Brusa
- Flow Cytometry Platform, Institute of Experimental and Clinical Research (IREC), Université Catholique de Louvain (UCLouvain), 1200, Brussels, Belgium
| | - Birgit Stierstorfer
- Drug Discovery Sciences, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany
| | - Holger Klein
- Global Computational Biology and Data Sciences, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany
| | - Bilal Singh
- Pole of Endocrinology, Diabetes, and Nutrition (EDIN), Institute of Experimental and Clinical Research (IREC), Université Catholique de Louvain (UCLouvain), 1200, Brussels, Belgium
| | - Lucie Ruiz
- Pole of Endocrinology, Diabetes, and Nutrition (EDIN), Institute of Experimental and Clinical Research (IREC), Université Catholique de Louvain (UCLouvain), 1200, Brussels, Belgium
| | - Michael Pieper
- Department of Cardiometabolic Disease Research, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany
| | - Michael Mark
- Department of Cardiometabolic Disease Research, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany
| | - Pedro L Herrera
- Department of Genetic Medicine and Development, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Fiona M Gribble
- Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, UK
| | - Frank Reimann
- Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, UK
| | - Anne Wojtusciszyn
- Laboratory of Cellular Therapy for Diabetes, University Hospital of Montpellier, Montpellier, France; Department of Endocrinology, Diabetes and Metabolism, Lausanne University Hospital, Lausanne, Switzerland
| | - Christophe Broca
- Laboratory of Cellular Therapy for Diabetes, University Hospital of Montpellier, Montpellier, France
| | - Nano Rita
- San Raffaele Diabetes Research Institute, IRCCS Ospedale San Raffaele, 20132, Milan, Italy
| | - Lorenzo Piemonti
- San Raffaele Diabetes Research Institute, IRCCS Ospedale San Raffaele, 20132, Milan, Italy; Università Vita-Salute San Raffaele, Milan, Italy
| | - Patrick Gilon
- Pole of Endocrinology, Diabetes, and Nutrition (EDIN), Institute of Experimental and Clinical Research (IREC), Université Catholique de Louvain (UCLouvain), 1200, Brussels, Belgium.
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79
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Berger C, Zdzieblo D. Glucose transporters in pancreatic islets. Pflugers Arch 2020; 472:1249-1272. [PMID: 32394191 PMCID: PMC7462922 DOI: 10.1007/s00424-020-02383-4] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 04/20/2020] [Accepted: 04/22/2020] [Indexed: 02/07/2023]
Abstract
The fine-tuning of glucose uptake mechanisms is rendered by various glucose transporters with distinct transport characteristics. In the pancreatic islet, facilitative diffusion glucose transporters (GLUTs), and sodium-glucose cotransporters (SGLTs) contribute to glucose uptake and represent important components in the glucose-stimulated hormone release from endocrine cells, therefore playing a crucial role in blood glucose homeostasis. This review summarizes the current knowledge about cell type-specific expression profiles as well as proven and putative functions of distinct GLUT and SGLT family members in the human and rodent pancreatic islet and further discusses their possible involvement in onset and progression of diabetes mellitus. In context of GLUTs, we focus on GLUT2, characterizing the main glucose transporter in insulin-secreting β-cells in rodents. In addition, we discuss recent data proposing that other GLUT family members, namely GLUT1 and GLUT3, render this task in humans. Finally, we summarize latest information about SGLT1 and SGLT2 as representatives of the SGLT family that have been reported to be expressed predominantly in the α-cell population with a suggested functional role in the regulation of glucagon release.
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Affiliation(s)
- Constantin Berger
- Tissue Engineering & Regenerative Medicine, University Hospital Würzburg, Röntgenring 11, 97070, Würzburg, Germany
| | - Daniela Zdzieblo
- Tissue Engineering & Regenerative Medicine, University Hospital Würzburg, Röntgenring 11, 97070, Würzburg, Germany.
- Fraunhofer Institute for Silicate Research (ISC), Translational Center Regenerative Therapies, Neunerplatz 2, 97082, Würzburg, Germany.
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80
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Perry RJ, Shulman GI. Sodium-glucose cotransporter-2 inhibitors: Understanding the mechanisms for therapeutic promise and persisting risks. J Biol Chem 2020; 295:14379-14390. [PMID: 32796035 DOI: 10.1074/jbc.rev120.008387] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Revised: 08/11/2020] [Indexed: 12/16/2022] Open
Abstract
In a healthy person, the kidney filters nearly 200 g of glucose per day, almost all of which is reabsorbed. The primary transporter responsible for renal glucose reabsorption is sodium-glucose cotransporter-2 (SGLT2). Based on the impact of SGLT2 to prevent renal glucose wasting, SGLT2 inhibitors have been developed to treat diabetes and are the newest class of glucose-lowering agents approved in the United States. By inhibiting glucose reabsorption in the proximal tubule, these agents promote glycosuria, thereby reducing blood glucose concentrations and often resulting in modest weight loss. Recent work in humans and rodents has demonstrated that the clinical utility of these agents may not be limited to diabetes management: SGLT2 inhibitors have also shown therapeutic promise in improving outcomes in heart failure, atrial fibrillation, and, in preclinical studies, certain cancers. Unfortunately, these benefits are not without risk: SGLT2 inhibitors predispose to euglycemic ketoacidosis in those with type 2 diabetes and, largely for this reason, are not approved to treat type 1 diabetes. The mechanism for each of the beneficial and harmful effects of SGLT2 inhibitors-with the exception of their effect to lower plasma glucose concentrations-is an area of active investigation. In this review, we discuss the mechanisms by which these drugs cause euglycemic ketoacidosis and hyperglucagonemia and stimulate hepatic gluconeogenesis as well as their beneficial effects in cardiovascular disease and cancer. In so doing, we aim to highlight the crucial role for selecting patients for SGLT2 inhibitor therapy and highlight several crucial questions that remain unanswered.
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Affiliation(s)
- Rachel J Perry
- Departments of Cellular and Molecular Physiology and Internal Medicine (Endocrinology), Yale School of Medicine, New Haven, Connecticut, USA
| | - Gerald I Shulman
- Departments of Cellular and Molecular Physiology and Internal Medicine (Endocrinology), Yale School of Medicine, New Haven, Connecticut, USA
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Dai C, Walker JT, Shostak A, Bouchi Y, Poffenberger G, Hart NJ, Jacobson DA, Calcutt MW, Bottino R, Greiner DL, Shultz LD, McGuinness OP, Dean ED, Powers AC. Dapagliflozin Does Not Directly Affect Human α or β Cells. Endocrinology 2020; 161:bqaa080. [PMID: 32428240 PMCID: PMC7375801 DOI: 10.1210/endocr/bqaa080] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 05/14/2020] [Indexed: 02/06/2023]
Abstract
Selective inhibitors of sodium glucose cotransporter-2 (SGLT2) are widely used for the treatment of type 2 diabetes and act primarily to lower blood glucose by preventing glucose reabsorption in the kidney. However, it is controversial whether these agents also act on the pancreatic islet, specifically the α cell, to increase glucagon secretion. To determine the effects of SGLT2 on human islets, we analyzed SGLT2 expression and hormone secretion by human islets treated with the SGLT2 inhibitor dapagliflozin (DAPA) in vitro and in vivo. Compared to the human kidney, SLC5A2 transcript expression was 1600-fold lower in human islets and SGLT2 protein was not detected. In vitro, DAPA treatment had no effect on glucagon or insulin secretion by human islets at either high or low glucose concentrations. In mice bearing transplanted human islets, 1 and 4 weeks of DAPA treatment did not alter fasting blood glucose, human insulin, and total glucagon levels. Upon glucose stimulation, DAPA treatment led to lower blood glucose levels and proportionally lower human insulin levels, irrespective of treatment duration. In contrast, after glucose stimulation, total glucagon was increased after 1 week of DAPA treatment but normalized after 4 weeks of treatment. Furthermore, the human islet grafts showed no effects of DAPA treatment on hormone content, endocrine cell proliferation or apoptosis, or amyloid deposition. These data indicate that DAPA does not directly affect the human pancreatic islet, but rather suggest an indirect effect where lower blood glucose leads to reduced insulin secretion and a transient increase in glucagon secretion.
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Affiliation(s)
- Chunhua Dai
- Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - John T Walker
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Alena Shostak
- Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Yasir Bouchi
- Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Greg Poffenberger
- Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Nathaniel J Hart
- Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - David A Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - M Wade Calcutt
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Rita Bottino
- Institute of Cellular Therapeutics, Allegheny-Singer Research Institute, Allegheny Health Network, Pittsburgh, Pennsylvania
| | - Dale L Greiner
- Department of Molecular Medicine, Diabetes Center of Excellence, University of Massachusetts Medical School, Worcester, Massachusetts
| | | | - Owen P McGuinness
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - E Danielle Dean
- Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Alvin C Powers
- Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
- VA Tennessee Valley Healthcare System, Nashville Tennessee
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82
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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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83
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Xu SFS, Andersen DB, Izarzugaza JMG, Kuhre RE, Holst JJ. In the rat pancreas, somatostatin tonically inhibits glucagon secretion and is required for glucose-induced inhibition of glucagon secretion. Acta Physiol (Oxf) 2020; 229:e13464. [PMID: 32145704 DOI: 10.1111/apha.13464] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 02/28/2020] [Accepted: 03/04/2020] [Indexed: 12/20/2022]
Abstract
AIM It is debated whether the inhibition of glucagon secretion by glucose results from direct effects of glucose on the α-cell (intrinsic regulation) or by paracrine effects exerted by beta- or delta-cell products. METHODS To study this in a more physiological model than isolated islets, we perfused isolated rat pancreases and measured glucagon, insulin and somatostatin secretion in response to graded increases in perfusate glucose concentration (from 3.5 to 4, 5, 6, 7, 8, 10, 12 mmol/L) as well as glucagon responses to blockage/activation of insulin/GABA/somatostatin signalling with or without addition of glucose. RESULTS Glucagon secretion was reduced by about 50% (compared to baseline secretion at 3.5 mmol/L) within minutes after increasing glucose from 4 to 5 mmol/L (P < .01, n = 13). Insulin secretion was increased minimally, but significantly, compared to baseline (3.5 mmol/L) at 4 mmol/L, whereas somatostatin secretion was not significantly increased from baseline until 7 mmol/L. Hereafter secretion of both increased gradually up to 12 mmol/L glucose. Neither recombinant insulin (1 µmol/L), GABA (300 µmol/L) or the insulin-receptor antagonist S961 (at 1 µmol/L) affected basal (3.5 mmol/L) or glucose-induced (5.0 mmol/L) attenuation of glucagon secretion (n = 7-8). Somatostatin-14 attenuated glucagon secretion by ~ 95%, and blockage of somatostatin-receptor (SSTR)-2 or combined blockage of SSTR-2, -3 and -5 by specific antagonists increased glucagon output (at 3.5 mmol/L glucose) and prevented glucose-induced (from 3.5 to 5.0 mmol/L) suppression of secretion. CONCLUSION Somatostatin is a powerful and tonic inhibitor of glucagon secretion from the rat pancreas and is required for glucose to inhibit glucagon secretion.
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Affiliation(s)
- Stella F. S. Xu
- 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
| | - Daniel B. Andersen
- 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
| | | | - Rune E. Kuhre
- Department of Biomedical Sciences Faculty of Health and Medical Sciences University of Copenhagen Copenhagen Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research Faculty of Health and Medical Sciences University of Copenhagen Copenhagen Denmark
| | - Jens J. Holst
- Department of Biomedical Sciences Faculty of Health and Medical Sciences University of Copenhagen Copenhagen Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research Faculty of Health and Medical Sciences University of Copenhagen Copenhagen Denmark
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84
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Abstract
PURPOSE OF REVIEW Impairment of glucose metabolism is commonly encountered in Cushing's syndrome. It is the source of significant morbidity and mortality even after successful treatment of Cushing's. This review is to understand the recent advances in understanding the pathophysiology of diabetes mellitus from excess cortisol. RECENT FINDINGS In-vitro studies have led to significant advancement in understanding the molecular effects of cortisol on glucose metabolism. Some of these findings have been translated with human data. There is marked reduction in insulin action and glucose disposal with a concomitant, insufficient increase in insulin secretion. Cortisol has a varied effect on adipose tissue, with increased lipolysis in subcutaneous adipose tissue in the extremities, and increased lipogenesis in visceral and subcutaneous truncal adipose tissue. SUMMARY Cushing's syndrome results in marked impairment in insulin action and glucose disposal resulting in hyperglycemia. Further studies are required to understand the effect on incretin secretion and action, gastric emptying, and its varied effect on adipose tissue.
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Affiliation(s)
- Anu Sharma
- Division of Diabetes and Endocrinology, University of Utah School of Medicine, Salt Lake City, UT
| | - Adrian Vella
- Division of Endocrinology, Diabetes, Metabolism and Nutrition, Mayo College of Medicine, Rochester, MN
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85
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Tellez K, Hang Y, Gu X, Chang CA, Stein RW, Kim SK. In vivo studies of glucagon secretion by human islets transplanted in mice. Nat Metab 2020; 2:547-557. [PMID: 32694729 PMCID: PMC7739959 DOI: 10.1038/s42255-020-0213-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 04/24/2020] [Indexed: 02/06/2023]
Abstract
Little is known about regulated glucagon secretion by human islet α-cells compared to insulin secretion from β-cells, despite conclusive evidence of dysfunction in both cell types in diabetes mellitus. Distinct insulins in humans and mice permit in vivo studies of human β-cell regulation after human islet transplantation in immunocompromised mice, whereas identical glucagon sequences prevent analogous in vivo measures of glucagon output from human α-cells. Here, we use CRISPR-Cas9 editing to remove glucagon codons 2-29 in immunocompromised NSG mice, preserving the production of other proglucagon-derived hormones. Glucagon knockout NSG (GKO-NSG) mice have metabolic, liver and pancreatic phenotypes associated with glucagon-signalling deficits that revert after transplantation of human islets from non-diabetic donors. Glucagon hypersecretion by transplanted islets from donors with type 2 diabetes revealed islet-intrinsic defects. We suggest that GKO-NSG mice provide an unprecedented resource to investigate human α-cell regulation in vivo.
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Affiliation(s)
- Krissie Tellez
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Yan Hang
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA
- Stanford Diabetes Research Center, Stanford University School of Medicine, Stanford, CA, USA
| | - Xueying Gu
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Charles A Chang
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Roland W Stein
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN, USA
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Seung K Kim
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA.
- Stanford Diabetes Research Center, Stanford University School of Medicine, Stanford, CA, USA.
- Department of Medicine (Endocrinology Division), Stanford University School of Medicine, Stanford, CA, USA.
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86
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Martinussen C, Veedfald S, Dirksen C, Bojsen-Møller KN, Svane MS, Wewer Albrechtsen NJ, van Hall G, Kristiansen VB, Fenger M, Holst JJ, Madsbad S. The effect of acute dual SGLT1/SGLT2 inhibition on incretin release and glucose metabolism after gastric bypass surgery. Am J Physiol Endocrinol Metab 2020; 318:E956-E964. [PMID: 32182123 DOI: 10.1152/ajpendo.00023.2020] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Enhanced meal-related enteroendocrine secretion, particularly of glucagon-like peptide-1 (GLP-1), contributes to weight-loss and improved glycemia after Roux-en-Y gastric bypass (RYGB). Dietary glucose drives GLP-1 and glucose-dependent insulinotropic polypeptide (GIP) secretion postoperatively. Understanding how glucose triggers incretin secretion following RYGB could lead to new treatments of diabetes and obesity. In vitro, incretin release depends on glucose absorption via sodium-glucose cotransporter 1 (SGLT1). We investigated the importance of SGLT1/SGLT2 for enteropancreatic hormone concentrations and glucose metabolism after RYGB in a randomized, controlled, crossover study. Ten RYGB-operated patients ingested 50 g of oral glucose with and without acute pretreatment with 600 mg of the SGLT1/SGLT2-inhibitor canagliflozin. Paracetamol and 3-O-methyl-d-glucopyranose (3-OMG) were added to the glucose drink to evaluate rates of intestinal entry and absorption of glucose, respectively. Blood samples were collected for 4 h. The primary outcome was 4-h plasma GLP-1 (incremental area-under the curve, iAUC). Secondary outcomes included glucose, GIP, insulin, and glucagon. Canagliflozin delayed glucose absorption (time-to-peak 3-OMG: 50 vs. 132 min, P < 0.01) but did not reduce iAUC GLP-1 (6,067 vs. 7,273·min·pmol-1·L-1, P = 0.23), although peak GLP-1 concentrations were lowered (-28%, P = 0.03). Canagliflozin reduced GIP (iAUC -28%, P = 0.01; peak concentrations -57%, P < 0.01), insulin, and glucose excursions, whereas plasma glucagon (AUC 3,216 vs. 4,160 min·pmol·L-1, P = 0.02) and amino acids were increased. In conclusion, acute SGLT1/SGLT2-inhibition during glucose ingestion did not reduce 4-h plasma GLP-1 responses in RYGB-patients but attenuated the early rise in GLP-1, GIP, and insulin, whereas late glucagon concentrations were increased. The results suggest that SGLT1-mediated glucose absorption contributes to incretin hormone secretion after RYGB.
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Affiliation(s)
- Christoffer Martinussen
- Department of Endocrinology, Hvidovre Hospital, Hvidovre, Denmark
- Danish Diabetes Academy, Odense, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Simon Veedfald
- Department of Endocrinology, Hvidovre Hospital, Hvidovre, Denmark
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Carsten Dirksen
- Department of Endocrinology, Hvidovre Hospital, Hvidovre, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Kirstine N Bojsen-Møller
- Department of Endocrinology, Hvidovre Hospital, Hvidovre, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Maria S Svane
- Department of Endocrinology, Hvidovre Hospital, Hvidovre, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Nicolai J Wewer Albrechtsen
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
- Department of Clinical Biochemistry, Rigshospitalet, Copenhagen, Denmark
| | - Gerrit van Hall
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
- Clinical Metabolomics Core Facility, Clinical Biochemistry, Rigshospitalet, Copenhagen, Denmark
| | - Viggo B Kristiansen
- Department of Surgical Gastroenterology, Hvidovre Hospital, Hvidovre, Denmark
| | - Mogens Fenger
- Department of Clinical Biochemistry, Hvidovre Hospital, Hvidovre, Denmark
| | - Jens J Holst
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Sten Madsbad
- Department of Endocrinology, Hvidovre Hospital, Hvidovre, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
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87
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Dapagliflozin not only improves hepatic injury and pancreatic endoplasmic reticulum stress, but also induces hepatic gluconeogenic enzymes expression in obese rats. Clin Sci (Lond) 2020; 133:2415-2430. [PMID: 31769484 DOI: 10.1042/cs20190863] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 11/12/2019] [Accepted: 11/26/2019] [Indexed: 02/06/2023]
Abstract
BACKGROUND With an increasing prevalence of obesity and metabolic syndrome, exploring the effects and delineating the mechanisms of possible therapeutic agents are of critical importance. We examined the effects of SGLT2 inhibitor-dapagliflozin on insulin resistance, hepatic gluconeogenesis, hepatic injury and pancreatic ER stress in high-fat diet-induced obese rats. MATERIALS AND METHODS Male Wistar rats were fed with normal diet (ND) or high-fat diet for 16 weeks. Then high-fat rats were given vehicle (HF) or dapagliflozin (1 mg/kg/day; HFDapa) or metformin (30 mg/kg/day; HFMet) for another 4 weeks. RESULTS We found that dapagliflozin ameliorated high-fat diet-induced insulin resistance. The fasting plasma glucose level was comparable among groups, although dapagliflozin treatment led to substantial glycosuria. Hepatic gluconeogenic enzymes, PEPCK, G6Pase and FBPase, expression was not different in HF rats compared with ND rats. Meanwhile, dapagliflozin-treated group exhibited the elevation of these enzymes in parallel with the rise of transcription factor CREB, co-factor PGC1α and upstream regulator SIRT1. Hepatic oxidative stress, inflammation and NAFLD activity score as well as hepatic and pancreatic ER stress and apoptosis in obese rats were attenuated by dapagliflozin. CONCLUSION We conclude that dapagliflozin improved obesity-related insulin resistance, hepatic and pancreatic injury independent of fasting plasma glucose level. Of note, dapagliflozin-induced glycosuria apparently triggered the up-regulation of hepatic gluconeogenic enzymes to prevent hypoglycemia.
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88
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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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89
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Affiliation(s)
- David J Hodson
- Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Edgbaston, U.K.
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, U.K
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Edgbaston, U.K
| | - Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford, U.K
- Nuffield Department of Clinical Medicine, University of Oxford, Oxford, U.K
- National Institute for Health Research Oxford Biomedical Research Centre, Churchill Hospital, Oxford, U.K
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90
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Saponaro C, Mühlemann M, Acosta-Montalvo A, Piron A, Gmyr V, Delalleau N, Moerman E, Thévenet J, Pasquetti G, Coddeville A, Cnop M, Kerr-Conte J, Staels B, Pattou F, Bonner C. Interindividual Heterogeneity of SGLT2 Expression and Function in Human Pancreatic Islets. Diabetes 2020; 69:902-914. [PMID: 31896553 DOI: 10.2337/db19-0888] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 12/27/2019] [Indexed: 11/13/2022]
Abstract
Studies implicating sodium-glucose cotransporter 2 (SGLT2) inhibitors in glucagon secretion by pancreatic α-cells reported controversial results. We hypothesized that interindividual heterogeneity in SGLT2 expression and regulation may affect glucagon secretion by human α-cells in response to SGLT2 inhibitors. An unbiased RNA-sequencing analysis of 207 donors revealed an unprecedented level of heterogeneity of SLC5A2 expression. To determine heterogeneity of SGLT2 expression at the protein level, the anti-SGLT2 antibody was first rigorously evaluated for specificity, followed by Western blot and immunofluorescence analysis on islets from 10 and 12 donors, respectively. The results revealed a high interdonor variability of SGLT2 protein expression. Quantitative analysis of 665 human islets showed a significant SGLT2 protein colocalization with glucagon but not with insulin or somatostatin. Moreover, glucagon secretion by islets from 31 donors at low glucose (1 mmol/L) was also heterogeneous and correlated with dapagliflozin-induced glucagon secretion at 6 mmol/L glucose. Intriguingly, islets from three donors did not secrete glucagon in response to either 1 mmol/L glucose or dapagliflozin, indicating a functional impairment of the islets of these donors to glucose sensing and SGLT2 inhibition. Collectively, these data suggest that heterogeneous expression of SGLT2 protein and variability in glucagon secretory responses contribute to interindividual differences in response to SGLT2 inhibitors.
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Affiliation(s)
- Chiara Saponaro
- INSERM, U1190, Lille, France
- European Genomic Institute for Diabetes, Lille, France
- University of Lille, Lille, France
| | - Markus Mühlemann
- INSERM, U1190, Lille, France
- European Genomic Institute for Diabetes, Lille, France
- University of Lille, Lille, France
| | - Ana Acosta-Montalvo
- INSERM, U1190, Lille, France
- European Genomic Institute for Diabetes, Lille, France
- University of Lille, Lille, France
| | - Anthony Piron
- ULB Center for Diabetes Research, Université Libre de Bruxelles, Brussels, Belgium
| | - Valery Gmyr
- INSERM, U1190, Lille, France
- European Genomic Institute for Diabetes, Lille, France
- University of Lille, Lille, France
| | - Nathalie Delalleau
- INSERM, U1190, Lille, France
- European Genomic Institute for Diabetes, Lille, France
- University of Lille, Lille, France
| | - Ericka Moerman
- INSERM, U1190, Lille, France
- European Genomic Institute for Diabetes, Lille, France
- University of Lille, Lille, France
| | - Julien Thévenet
- INSERM, U1190, Lille, France
- European Genomic Institute for Diabetes, Lille, France
- University of Lille, Lille, France
| | - Gianni Pasquetti
- INSERM, U1190, Lille, France
- European Genomic Institute for Diabetes, Lille, France
- University of Lille, Lille, France
| | - Anais Coddeville
- INSERM, U1190, Lille, France
- European Genomic Institute for Diabetes, Lille, France
- University of Lille, Lille, France
| | - Miriam Cnop
- ULB Center for Diabetes Research, Université Libre de Bruxelles, Brussels, Belgium
- Division of Endocrinology, Erasmus Hospital, Université Libre de Bruxelles, Brussels, Belgium
| | - Julie Kerr-Conte
- INSERM, U1190, Lille, France
- European Genomic Institute for Diabetes, Lille, France
- University of Lille, Lille, France
| | - Bart Staels
- European Genomic Institute for Diabetes, Lille, France
- University of Lille, Lille, France
- INSERM, U1011, Lille, France
- Service Biochimie automatisée Pathologies des protéines, CHU Lille, Lille, France
- Institut Pasteur de Lille, Lille, France
| | - François Pattou
- INSERM, U1190, Lille, France
- European Genomic Institute for Diabetes, Lille, France
- University of Lille, Lille, France
- Chirurgie Endocrinienne et Métabolique, CHU Lille, Lille, France
| | - Caroline Bonner
- INSERM, U1190, Lille, France
- European Genomic Institute for Diabetes, Lille, France
- University of Lille, Lille, France
- Institut Pasteur de Lille, Lille, France
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91
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Israël M, Schwartz L. Inhibition of the ketolytic acetyl CoA supply to tumors could be their "Achilles heel". Int J Cancer 2020; 147:1755-1757. [PMID: 32181876 DOI: 10.1002/ijc.32979] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 03/05/2020] [Accepted: 03/13/2020] [Indexed: 12/13/2022]
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92
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Bouzakri K, Veyrat-Durebex C, Holterman C, Arous C, Barbieux C, Bosco D, Altirriba J, Alibashe M, Tournier BB, Gunton JE, Mouche S, Bietiger W, Forterre A, Berney T, Pinget M, Christofori G, Kennedy C, Szanto I. Beta-Cell-Specific Expression of Nicotinamide Adenine Dinucleotide Phosphate Oxidase 5 Aggravates High-Fat Diet-Induced Impairment of Islet Insulin Secretion in Mice. Antioxid Redox Signal 2020; 32:618-635. [PMID: 31931619 DOI: 10.1089/ars.2018.7579] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Aims: Nicotinamide adenine dinucleotide phosphate oxidases (NOX-es) produce reactive oxygen species and modulate β-cell insulin secretion. Islets of type 2 diabetic subjects present elevated expression of NOX5. Here, we sought to characterize regulation of NOX5 expression in human islets in vitro and to uncover the relevance of NOX5 in islet function in vivo using a novel mouse model expressing NOX5 in doxycycline-inducible, β-cell-specific manner (RIP/rtTA/NOX5 mice). Results:In situ hybridization and immunohistochemistry employed on pancreatic sections demonstrated NOX5 messenger ribonucleic acid (mRNA) and protein expressions in human islets. In cultures of dispersed islets, NOX5 protein was observed in somatostatin-positive (δ) cells in basal (2.8 mM glucose) conditions. Small interfering ribonucleic acid (siRNA)-mediated knockdown of NOX5 in human islets cultured in basal glucose concentrations resulted in diminished glucose-induced insulin secretion (GIIS) in vitro. However, when islets were preincubated in high (16.7 mM) glucose media for 12 h, NOX5 appeared also in insulin-positive (β) cells. In vivo, mice with β-cell NOX5 expression developed aggravated impairment of GIIS compared with control mice when challenged with 14 weeks of high-fat diet. Similarly, in vitro palmitate preincubation resulted in more severe reduction of insulin release in islets of RIP/rtTA/NOX5 mice compared with their control littermates. Decreased insulin secretion was most distinct in response to theophylline stimulation, suggesting impaired cyclic adenosine monophosphate (cAMP)-mediated signaling due to increased phosphodiesterase activation. Innovation and Conclusions: Our data provide the first insight into the complex regulation and function of NOX5 in islets implying an important role for NOX5 in δ-cell-mediated intraislet crosstalk in physiological circumstances but also identifying it as an aggravating factor in β-cell failure in diabetic conditions.
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Affiliation(s)
- Karim Bouzakri
- Department of Genetic Medicine and Development, University of Geneva, Geneva, Switzerland.,Centre Européen d'Etude du Diabète, Strasbourg, France
| | | | - Chet Holterman
- Division of Nephrology, Department of Medicine, Kidney Research Centre, Ottawa Hospital Research Institute, Ottawa, Canada
| | - Caroline Arous
- Department of Genetic Medicine and Development, University of Geneva, Geneva, Switzerland.,Department of Cellular Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - Charlotte Barbieux
- Cell Isolation and Transplantation Center, Department of Surgery, Geneva University Hospitals and University of Geneva, Geneva, Switzerland
| | - Domenico Bosco
- Cell Isolation and Transplantation Center, Department of Surgery, Geneva University Hospitals and University of Geneva, Geneva, Switzerland
| | - Jordi Altirriba
- Laboratory of Metabolism, Department of Internal Medicine, Geneva University Hospitals, Geneva, Switzerland
| | - Mohamed Alibashe
- Cell Isolation and Transplantation Center, Department of Surgery, Geneva University Hospitals and University of Geneva, Geneva, Switzerland
| | - Benjamin B Tournier
- Vulnerability Biomarkers Unit, Division of General Psychiatry, Department of Psychiatry, University Hospitals of Geneva, Geneva, Switzerland
| | - Jenny E Gunton
- Centre for Diabetes, Obesity and Endocrinology, Westmead Millennium Institute, The University of Sydney, Sydney, Australia.,Diabetes and Transcription Factors Group, Garvan Institute of Medical Research, Sydney, Australia
| | - Sarah Mouche
- Department of Cellular Physiology and Metabolism, University of Geneva, Geneva, Switzerland.,Department of Internal Medicine, Geneva University Hospitals and University of Geneva, Geneva, Switzerland
| | | | | | - Thierry Berney
- Division of Transplantation, Department of Surgery, University Hospitals of Geneva, Geneva, Switzerland
| | - Michel Pinget
- Centre Européen d'Etude du Diabète, Strasbourg, France
| | | | - Christopher Kennedy
- Division of Nephrology, Department of Medicine, Kidney Research Centre, Ottawa Hospital Research Institute, Ottawa, Canada
| | - Ildiko Szanto
- Department of Internal Medicine, Geneva University Hospitals and University of Geneva, Geneva, Switzerland.,Diabetes Center of the Faculty of Medicine at the University of Geneva, Geneva, Switzerland
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93
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Hartig SM, Cox AR. Paracrine signaling in islet function and survival. J Mol Med (Berl) 2020; 98:451-467. [PMID: 32067063 DOI: 10.1007/s00109-020-01887-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 02/05/2020] [Accepted: 02/11/2020] [Indexed: 02/06/2023]
Abstract
The pancreatic islet is a dense cellular network comprised of several cell types with endocrine function vital in the control of glucose homeostasis, metabolism, and feeding behavior. Within the islet, endocrine hormones also form an intricate paracrine network with supportive cells (endothelial, neuronal, immune) and secondary signaling molecules regulating cellular function and survival. Modulation of these signals has potential consequences for diabetes development, progression, and therapeutic intervention. Beta cell loss, reduced endogenous insulin secretion, and dysregulated glucagon secretion are hallmark features of both type 1 and 2 diabetes that not only impact systemic regulation of glucose, but also contribute to the function and survival of cells within the islet. Advancing research and technology have revealed new islet biology (cellular identity and transcriptomes) and identified previously unrecognized paracrine signals and mechanisms (somatostatin and ghrelin paracrine actions), while shifting prior views of intraislet communication. This review will summarize the paracrine signals regulating islet endocrine function and survival, the disruption and dysfunction that occur in diabetes, and potential therapeutic targets to preserve beta cell mass and function.
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Affiliation(s)
- Sean M Hartig
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Baylor College of Medicine, Houston, TX, 77030, USA
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Aaron R Cox
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Baylor College of Medicine, Houston, TX, 77030, USA.
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94
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Cherkas A, Holota S, Mdzinarashvili T, Gabbianelli R, Zarkovic N. Glucose as a Major Antioxidant: When, What for and Why It Fails? Antioxidants (Basel) 2020; 9:antiox9020140. [PMID: 32033390 PMCID: PMC7070274 DOI: 10.3390/antiox9020140] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 02/01/2020] [Accepted: 02/03/2020] [Indexed: 02/07/2023] Open
Abstract
A human organism depends on stable glucose blood levels in order to maintain its metabolic needs. Glucose is considered to be the most important energy source, and glycolysis is postulated as a backbone pathway. However, when the glucose supply is limited, ketone bodies and amino acids can be used to produce enough ATP. In contrast, for the functioning of the pentose phosphate pathway (PPP) glucose is essential and cannot be substituted by other metabolites. The PPP generates and maintains the levels of nicotinamide adenine dinucleotide phosphate (NADPH) needed for the reduction in oxidized glutathione and protein thiols, the synthesis of lipids and DNA as well as for xenobiotic detoxification, regulatory redox signaling and counteracting infections. The flux of glucose into a PPP—particularly under extreme oxidative and toxic challenges—is critical for survival, whereas the glycolytic pathway is primarily activated when glucose is abundant, and there is lack of NADP+ that is required for the activation of glucose-6 phosphate dehydrogenase. An important role of glycogen stores in resistance to oxidative challenges is discussed. Current evidences explain the disruptive metabolic effects and detrimental health consequences of chronic nutritional carbohydrate overload, and provide new insights into the positive metabolic effects of intermittent fasting, caloric restriction, exercise, and ketogenic diet through modulation of redox homeostasis.
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Affiliation(s)
- Andriy Cherkas
- Department of Internal Medicine # 1, Lviv National Medical University, 79010 Lviv, Ukraine
- Correspondence:
| | - Serhii Holota
- Department of Pharmaceutical, Organic and Bioorganic Chemistry, Lviv National Medical University, 79010 Lviv, Ukraine;
- Department of Organic Chemistry and Pharmacy, Lesya Ukrainka Eastern European National University, 43025 Lutsk, Ukraine
| | - Tamaz Mdzinarashvili
- Institute of Medical and Applied Biophysics, I. Javakhishvili Tbilisi State University, 0128 Tbilisi, Georgia;
| | - Rosita Gabbianelli
- Unit of Molecular Biology, School of Pharmacy, University of Camerino, 62032 Camerino, Italy;
| | - Neven Zarkovic
- Laboratory for Oxidative Stress (LabOS), Institute “Rudjer Boskovic”, HR-10000 Zagreb, Croatia;
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95
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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: 29] [Impact Index Per Article: 7.3] [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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96
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Yi Z, Waseem Ghani M, Ghani H, Jiang W, Waseem Birmani M, Ye L, Bin L, Cun LG, Lilong A, Mei X. Gimmicks of gamma-aminobutyric acid (GABA) in pancreatic β-cell regeneration through transdifferentiation of pancreatic α- to β-cells. Cell Biol Int 2020; 44:926-936. [PMID: 31903671 DOI: 10.1002/cbin.11302] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 01/04/2020] [Indexed: 02/06/2023]
Abstract
In vivo regeneration of lost or dysfunctional islet β cells can fulfill the promise of improved therapy for diabetic patients. To achieve this, many mitogenic factors have been attempted, including gamma-aminobutyric acid (GABA). GABA remarkably affects pancreatic islet cells' (α cells and β cells) function through paracrine and/or autocrine binding to its membrane receptors on these cells. GABA has also been studied for promoting the transformation of α cells to β cells. Nonetheless, the gimmickry of GABA-induced α-cell transformation to β cells has two different perspectives. On the one hand, GABA was found to induce α-cell transformation to β cells in vivo and insulin-secreting β-like cells in vitro. On the other hand, GABA treatment showed that it has no α- to β-cell transformation response. Here, we will summarize the physiological effects of GABA on pancreatic islet β cells with an emphasis on its regenerative effects for transdifferentiation of islet α cells to β cells. We will also critically discuss the controversial results about GABA-mediated transdifferentiation of α cells to β cells.
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Affiliation(s)
- Zhao Yi
- Department of Animal Science and Medicine, Agricultural College, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China.,Department of Animal Breeding, Genetics and Reproduction, Agricultural Collage, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China
| | - Muhammad Waseem Ghani
- Department of Animal Science and Medicine, Agricultural College, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China.,Department of Animal Breeding, Genetics and Reproduction, Agricultural Collage, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China
| | - Hammad Ghani
- Nawaz Sharif Medical College, University of Gujrat, Punjab, 50180, Pakistan
| | - Wu Jiang
- Department of Animal Science and Medicine, Agricultural College, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China.,Department of Animal Breeding, Genetics and Reproduction, Agricultural Collage, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China
| | - Muhammad Waseem Birmani
- Department of Animal Science and Medicine, Agricultural College, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China
| | - Li Ye
- Department of Animal Science and Medicine, Agricultural College, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China.,Department of Animal Breeding, Genetics and Reproduction, Agricultural Collage, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China
| | - Liu Bin
- Department of Animal Science and Medicine, Agricultural College, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China.,Department of Animal Breeding, Genetics and Reproduction, Agricultural Collage, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China
| | - Lang Guan Cun
- Department of Animal Science and Medicine, Agricultural College, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China.,Department of Animal Breeding, Genetics and Reproduction, Agricultural Collage, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China
| | - An Lilong
- Department of Animal Science and Medicine, Agricultural College, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China
| | - Xiao Mei
- Department of Animal Science and Medicine, Agricultural College, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China.,Department of Animal Breeding, Genetics and Reproduction, Agricultural Collage, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China
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97
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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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98
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Bru-Tari E, Oropeza D, Herrera PL. Cell Heterogeneity and Paracrine Interactions in Human Islet Function: A Perspective Focused in β-Cell Regeneration Strategies. Front Endocrinol (Lausanne) 2020; 11:619150. [PMID: 33613453 PMCID: PMC7888438 DOI: 10.3389/fendo.2020.619150] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Accepted: 12/14/2020] [Indexed: 12/27/2022] Open
Abstract
The β-cell regeneration field has shown a strong knowledge boost in the last 10 years. Pluripotent stem cell differentiation and direct reprogramming from other adult cell types are becoming more tangible long-term diabetes therapies. Newly generated β-like-cells consistently show hallmarks of native β-cells and can restore normoglycemia in diabetic mice in virtually all recent studies. Nonetheless, these cells still show important compromises in insulin secretion, cell metabolism, electrical activity, and overall survival, perhaps due to a lack of signal integration from other islet cells. Mounting data suggest that diabetes is not only a β-cell disease, as the other islet cell types also contribute to its physiopathology. Here, we present an update on the most recent studies of islet cell heterogeneity and paracrine interactions in the context of restoring an integrated islet function to improve β-cell replacement therapies.
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99
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Vergari E, Denwood G, Salehi A, Zhang Q, Adam J, Alrifaiy A, Wernstedt Asterholm I, Benrick A, Chibalina MV, Eliasson L, Guida C, Hill TG, Hamilton A, Ramracheya R, Reimann F, Rorsman NJG, Spilliotis I, Tarasov AI, Walker JN, Rorsman P, Briant LJB. Somatostatin secretion by Na +-dependent Ca 2+-induced Ca 2+ release in pancreatic delta-cells. Nat Metab 2020; 2:32-40. [PMID: 31993555 PMCID: PMC6986923 DOI: 10.1038/s42255-019-0158-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Pancreatic islets are complex micro-organs consisting of at least three different cell types: glucagon-secreting α-, insulin-producing β- and somatostatin-releasing δ-cells1. Somatostatin is a powerful paracrine inhibitor of insulin and glucagon secretion2. In diabetes, increased somatostatinergic signalling leads to defective counter-regulatory glucagon secretion3. This increases the risk of severe hypoglycaemia, a dangerous complication of insulin therapy4. The regulation of somatostatin secretion involves both intrinsic and paracrine mechanisms5 but their relative contributions and whether they interact remains unclear. Here we show that dapagliflozin-sensitive glucose- and insulin-dependent sodium uptake stimulates somatostatin secretion by elevating the cytoplasmic Na+ concentration ([Na+]i) and promoting intracellular Ca2+-induced Ca2+ release (CICR). This mechanism also becomes activated when [Na+]i is elevated following the inhibition of the plasmalemmal Na+-K+ pump by reductions of the extracellular K+ concentration emulating those produced by exogenous insulin in vivo 6. Islets from some donors with type-2 diabetes hypersecrete somatostatin, leading to suppression of glucagon secretion that can be alleviated by a somatostatin receptor antagonist. Our data highlight the role of Na+ as an intracellular second messenger, illustrate the significance of the intraislet paracrine network and provide a mechanistic framework for pharmacological correction of the hormone secretion defects associated with diabetes that selectively target the δ-cells.
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Affiliation(s)
- Elisa Vergari
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, Churchill Hospital, Oxford, UK
| | - Geoffrey Denwood
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, Churchill Hospital, Oxford, UK
| | - Albert Salehi
- Department of Neuroscience and Physiology, University of Göteborg, Göteborg, Sweden
- Department of Clinical Sciences Malmö, Clinical Research Centre, Malmö, Sweden
| | - Quan Zhang
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, Churchill Hospital, Oxford, UK
| | - Julie Adam
- Nuffield Department of Clinical Medicine, University of Oxford, NDM Research Building, Oxford, UK
| | - Ahmed Alrifaiy
- Department of Neuroscience and Physiology, University of Göteborg, Göteborg, Sweden
| | | | - Anna Benrick
- Department of Neuroscience and Physiology, University of Göteborg, Göteborg, Sweden
| | - Margarita V Chibalina
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, Churchill Hospital, Oxford, UK
| | - Lena Eliasson
- Department of Clinical Sciences Malmö, Clinical Research Centre, Malmö, Sweden
| | - Claudia Guida
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, Churchill Hospital, Oxford, UK
| | - Thomas G Hill
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, Churchill Hospital, Oxford, UK
| | - Alexander Hamilton
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, Churchill Hospital, Oxford, UK
- Department of Clinical Sciences Malmö, Clinical Research Centre, Malmö, Sweden
| | - Reshma Ramracheya
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, Churchill Hospital, Oxford, UK
| | - Frank Reimann
- MRC Metabolic Diseases Unit, University of Cambridge Metabolic Research Laboratories, WT-MRC Institute of Metabolic Science, University of Cambridge, Cambridge, UK
| | - Nils J G Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, Churchill Hospital, Oxford, UK
| | - Ioannis Spilliotis
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, Churchill Hospital, Oxford, UK
- Oxford National Institute for Health Research, Biomedical Research Centre, Churchill Hospital, Oxford, UK
| | - Andrei I Tarasov
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, Churchill Hospital, Oxford, UK
- Oxford National Institute for Health Research, Biomedical Research Centre, Churchill Hospital, Oxford, UK
| | - Jonathan N Walker
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, Churchill Hospital, Oxford, UK
- MacLeod Diabetes and Endocrine Centre, Royal Devon and Exeter Hospital, Exeter, UK
| | - Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, Churchill Hospital, Oxford, UK.
- Department of Neuroscience and Physiology, University of Göteborg, Göteborg, Sweden.
- Oxford National Institute for Health Research, Biomedical Research Centre, Churchill Hospital, Oxford, UK.
| | - Linford J B Briant
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, Churchill Hospital, Oxford, UK.
- Department of Computer Science, University of Oxford, Oxford, UK.
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100
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Elsakr JM, Deeter C, Ricciardi V, Gannon M. Analysis of Non-Human Primate Pancreatic Islet Oxygen Consumption. J Vis Exp 2019:10.3791/60696. [PMID: 31904022 PMCID: PMC7607517 DOI: 10.3791/60696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
The measurement of oxygen consumption in spheroid clusters of cells, such as ex vivo pancreatic islets, has historically been challenging. We demonstrate the measurement of islet oxygen consumption using a 96-well microplate designed for the measurement of oxygen consumption in spheroids. In this assay, spheroid microplates are coated with a cell and tissue adhesive on the day prior to the assay. We utilize a small volume of adhesive solution to encourage islet adherence to only the bottom of the well. On the day of the assay, 15 islets are loaded directly into the base of each well using a technique that ensures optimal positioning of islets and accurate measurement of oxygen consumption. Various aspects of mitochondrial respiration are probed pharmacologically in non-human primate islets, including ATP-dependent respiration, maximal respiration, and proton leak. This method allows for consistent, reproducible results using only a small number of islets per well. It can theoretically be applied to any cultured spheroids of similar size.
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Affiliation(s)
- Joseph M Elsakr
- Department of Molecular Physiology and Biophysics, Vanderbilt University
| | | | | | - Maureen Gannon
- Department of Molecular Physiology and Biophysics, Vanderbilt University; Department of Veterans Affairs Tennessee Valley; Department of Medicine, Vanderbilt University Medical Center; Department of Cell and Developmental Biology, Vanderbilt University;
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