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Krishnan G, Bagath M, Devaraj C, Soren NM. The signalling association of glucagon-like peptide-1 and its receptors in the gastrointestinal tract and GPR40 and insulin receptor in the pancreas of sheep. Gen Comp Endocrinol 2024; 358:114602. [PMID: 39226991 DOI: 10.1016/j.ygcen.2024.114602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2024] [Revised: 08/19/2024] [Accepted: 08/31/2024] [Indexed: 09/05/2024]
Abstract
The present study was aimed at gaining insight into the signalling relationship between glucagon-like peptide-1 (GLP-1) and its receptor (GLP-1R) in the regulation of glucose metabolism. Further, to assess the role of G-protein-coupled receptor 40 (GPR40) and insulin receptor (INSR) in the pancreas of sheep that were supplemented with calcium salts of long-chain fatty acids (CSFAs). An experiment was carried out over a period of 60 days with eighteen sheep, and they were fed with a standard basal diet. The sheep were divided into three groups: CSFA0 (without CSFAs), while CSFA3 and CSFA5 were supplemented with 3 % and 5 % of CSFAs, respectively. Plasma concentrations of GLP-1, insulin, glucagon, and glucose were assessed every two weeks. At the end of the experiment, sheep were slaughtered, and samples of gastrointestinal tract (GIT) epithelial tissues and pancreas were collected to assess the relative expression of mRNA of GPR40, GLP-1R, and INSR. Postprandial GLP-1 and insulin were increased by 3.7-4.1 and 1.45-1.5 times, respectively, in the CSFAs-supplemented groups compared to CSFA0. Post-feeding, glucagon and glucose levels decreased in CSFA3 and CSFA5 compared to CSFA0. The results indicated that the supplementation of LCFAs increased the expression of GLP-1R in the GIT and pancreas, as well as the mRNA of GPR40 and INSR in the pancreas. Chemosensing of LCFAs by GPR40 in the pancreas triggers signalling transduction, and enhanced GLP-1 and GLP-1R resulted in moderately increased insulin secretion and reduced glucagon levels. These combined effects, along with the glucose-lowering effect of GLP-1, effectively lowered glucose levels in normoglycemic sheep.
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Affiliation(s)
- G Krishnan
- Animal Physiology Division, ICAR-National Institute of Animal Nutrition and Physiology, Bangalore 560030, India.
| | - M Bagath
- Animal Nutrition Division, ICAR-National Institute of Animal Nutrition and Physiology, Bangalore 560030, India
| | - C Devaraj
- Bioenergetics and Environmental Sciences Division, ICAR-National Institute of Animal Nutrition and Physiology, Bangalore 560030, India
| | - N M Soren
- Animal Nutrition Division, ICAR-National Institute of Animal Nutrition and Physiology, Bangalore 560030, India
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2
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Peart LA, Draper M, Tarasov AI. The impact of GLP-1 signalling on the energy metabolism of pancreatic islet β-cells and extrapancreatic tissues. Peptides 2024; 178:171243. [PMID: 38788902 DOI: 10.1016/j.peptides.2024.171243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Revised: 05/19/2024] [Accepted: 05/21/2024] [Indexed: 05/26/2024]
Abstract
Glucagon-like peptide-1 signalling impacts glucose homeostasis and appetite thereby indirectly affecting substrate availability at the whole-body level. The incretin canonically produces an insulinotropic effect, thereby lowering blood glucose levels by promoting the uptake and inhibiting the production of the sugar by peripheral tissues. Likewise, GLP-1 signalling within the central nervous system reduces the appetite and food intake, whereas its gastric effect delays the absorption of nutrients, thus improving glycaemic control and reducing the risk of postprandial hyperglycaemia. We review the molecular aspects of the GLP-1 signalling, focusing on its impact on intracellular energy metabolism. Whilst the incretin exerts its effects predominantly via a Gs receptor, which decodes the incretin signal into the elevation of intracellular cAMP levels, the downstream signalling cascades within the cell, acting on fast and slow timescales, resulting in an enhancement or an attenuation of glucose catabolism, respectively.
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Affiliation(s)
- Leah A Peart
- School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine, Northern Ireland BT52 1SA, UK
| | - Matthew Draper
- School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine, Northern Ireland BT52 1SA, UK
| | - Andrei I Tarasov
- School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine, Northern Ireland BT52 1SA, UK.
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Shi W, Zhang L, Zhao Y, Li X. Exendin-4 Caused Growth Arrest by Regulating Sugar Metabolism in Hyphantria cunea (Lepidoptera: Erebidae) Larvae. INSECTS 2024; 15:503. [PMID: 39057236 PMCID: PMC11276936 DOI: 10.3390/insects15070503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2024] [Revised: 07/01/2024] [Accepted: 07/04/2024] [Indexed: 07/28/2024]
Abstract
Insects' growth and development are highly dependent on energy supply, with sugar metabolism playing a pivotal role in maintaining homeostasis and regulating physiological processes. The present study investigated the effects of exendin-4, a glucagon-like peptide-1 receptor (GLP-1R) agonist, on the growth, development, glycolysis, and energy metabolism of fourth-instar larvae of the fall webworm, Hyphantria cunea. We determined the impact of exendin-4 on larval growth and nutritional indices, analyzed the responses of glycolytic and metabolic pathways, and revealed the underlying regulatory mechanisms. Exendin-4 treatment significantly decreased growth and nutritional indices, influenced the activity of digestive enzymes, and induced changes in metabolite profiles, particularly affecting energy substance metabolism. We observed an increase in the glycogen content and a decrease in glucose and trehalose levels in the hemolymph, suggesting a regulatory effect on blood sugar homeostasis. Furthermore, exendin-4 promoted glycolysis by enhancing the activities and expressions of key glycolytic enzymes, leading to an increase in pyruvate production. This was accompanied by a reduction in ATP levels and the activation of AMP-activated protein kinase (AMPK), which may underlie the growth arrest in larvae. Our findings provide novel insights into the effects of exendin-4 on insect responses from an energy metabolism perspective and may contribute to the development of GLP-1R agonists for pest management.
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Affiliation(s)
- Wenhui Shi
- College of Wildlife and Protected Area, Northeast Forestry University, Harbin 150040, China;
| | - Lu Zhang
- College of Forestry, Northeast Forestry University, Harbin 150040, China;
| | - Yuecheng Zhao
- College of Forestry and Grassland Science, Jilin Agricultural University, Changchun 130118, China
| | - Xingpeng Li
- College of Forestry, Beihua University, Jilin 132013, China
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Noguchi GM, Castillo VC, Donaldson CJ, Flisher MR, Momen AT, Saghatelian A, Huising MO. Urocortin 3 contributes to paracrine inhibition of islet alpha cells in mice. J Endocrinol 2024; 261:e240018. [PMID: 38593829 PMCID: PMC11095665 DOI: 10.1530/joe-24-0018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Accepted: 04/08/2024] [Indexed: 04/11/2024]
Abstract
Pancreatic alpha cell activity and glucagon secretion lower as glucose levels increase. While part of the decrease is regulated by glucose itself, paracrine signaling by their neighboring beta and delta cells also plays an important role. Somatostatin from delta cells is an important local inhibitor of alpha cells at high glucose. Additionally, urocortin 3 (UCN3) is a hormone that is co-released from beta cells with insulin and acts locally to potentiate somatostatin secretion from delta cells. UCN3 thus inhibits insulin secretion via a negative feedback loop with delta cells, but its role with respect to alpha cells and glucagon secretion is not understood. We hypothesize that the somatostatin-driven glucagon inhibition at high glucose is regulated in part by UCN3 from beta cells. Here, we use a combination of live functional Ca2+ and cAMP imaging as well as direct glucagon secretion measurement, all from alpha cells in intact mouse islets, to determine the contributions of UCN3 to alpha cell behavior. Exogenous UCN3 treatment decreased alpha cell Ca2+ and cAMP levels and inhibited glucagon release. Blocking endogenous UCN3 signaling increased alpha cell Ca2+ by 26.8 ± 7.6%, but this did not result in increased glucagon release at high glucose. Furthermore, constitutive deletion of Ucn3 did not increase Ca2+ activity or glucagon secretion relative to controls. UCN3 is thus capable of inhibiting mouse alpha cells, but, given the subtle effects of endogenous UCN3 signaling on alpha cells, we propose that UCN3-driven somatostatin may serve to regulate local paracrine glucagon levels in the islet instead of inhibiting gross systemic glucagon release.
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Affiliation(s)
- Glyn M. Noguchi
- Department of Neurobiology, Physiology & Behavior, University of California Davis, Davis, CA, USA
| | - Vincent C. Castillo
- Department of Neurobiology, Physiology & Behavior, University of California Davis, Davis, CA, USA
| | | | - Marcus R. Flisher
- Department of Neurobiology, Physiology & Behavior, University of California Davis, Davis, CA, USA
| | - Ariana T. Momen
- Department of Neurobiology, Physiology & Behavior, University of California Davis, Davis, CA, USA
| | | | - Mark O. Huising
- Department of Neurobiology, Physiology & Behavior, University of California Davis, Davis, CA, USA
- Department of Physiology & Membrane Biology, University of California Davis, Davis, CA, USA
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Acreman S, Ma J, Denwood G, Gao R, Tarasov A, Rorsman P, Zhang Q. The endoplasmic reticulum plays a key role in α-cell intracellular Ca 2+ dynamics and glucose-regulated glucagon secretion in mouse islets. iScience 2024; 27:109665. [PMID: 38646167 PMCID: PMC11033163 DOI: 10.1016/j.isci.2024.109665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 02/13/2024] [Accepted: 04/02/2024] [Indexed: 04/23/2024] Open
Abstract
Glucagon is secreted by pancreatic α-cells to counteract hypoglycaemia. How glucose regulates glucagon secretion remains unclear. Here, using mouse islets, we studied the role of transmembrane and endoplasmic reticulum (ER) Ca2+ on intrinsic α-cell glucagon secretion. Blocking isradipine-sensitive L-type voltage-gated Ca2+ (Cav) channels abolished α-cell electrical activity but had little impact on its cytosolic Ca2+ oscillations or low-glucose-stimulated glucagon secretion. In contrast, depleting ER Ca2+ with cyclopiazonic acid or blocking ER Ca2+-releasing ryanodine receptors abolished α-cell glucose sensitivity and low-glucose-stimulated glucagon secretion. ER Ca2+ mobilization in α-cells is regulated by intracellular ATP and likely to be coupled to Ca2+ influx through P/Q-type Cav channels. ω-Agatoxin IVA blocked α-cell ER Ca2+ release and cell exocytosis, but had no additive effect on glucagon secretion when combined with ryanodine. We conclude that glucose regulates glucagon secretion through the control of ER Ca2+ mobilization, a mechanism that can be independent of α-cell electrical activity.
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Affiliation(s)
- Samuel Acreman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 7LE, UK
- Institute of Neuroscience and Physiology, Department of Physiology, Metabolic Research Unit, Sahlgrenska Academy, University of Gothenburg, Box 430, S-405 30 Gothenburg, Sweden
| | - Jinfang Ma
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 7LE, UK
- Department of Endocrinology and Metabolism, West China Hospital, Sichuan University, Chengdu, China
| | - Geoffrey Denwood
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 7LE, UK
| | - Rui Gao
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 7LE, UK
| | - Andrei Tarasov
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 7LE, UK
- Biomedical Sciences Research Institute, School of Biomedical Sciences, Ulster University, Coleraine, Northern Ireland, UK
| | - Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 7LE, UK
- Institute of Neuroscience and Physiology, Department of Physiology, Metabolic Research Unit, Sahlgrenska Academy, University of Gothenburg, Box 430, S-405 30 Gothenburg, Sweden
- Biomedical Sciences Research Institute, School of Biomedical Sciences, Ulster University, Coleraine, Northern Ireland, UK
| | - Quan Zhang
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 7LE, UK
- CNC - Center for Neuroscience and Cell Biology, CIBB - Centre for Innovative Biomedicine and Biotechnology, University of Coimbra, Coimbra, Portugal
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Kaur M, Misra S. A review of an investigational drug retatrutide, a novel triple agonist agent for the treatment of obesity. Eur J Clin Pharmacol 2024; 80:669-676. [PMID: 38367045 DOI: 10.1007/s00228-024-03646-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Accepted: 02/02/2024] [Indexed: 02/19/2024]
Abstract
BACKGROUND Obesity is one of the critical public health problems in our society. It leads to various health conditions, such as type 2 diabetes mellitus, cardiovascular disease, hypertension, dyslipidaemia, and non-alcoholic fatty liver disease. With the rising incidence of obesity, there is a growing demand for new therapies which can effectively manage body weight and improve health. CURRENT EVIDENCE Currently under development, multi-receptor agonist drugs may offer a promising solution to meet this unmet medical need. Retatrutide is a novel triple receptor agonist peptide that targets the glucagon receptor (GCGR), glucose-dependent insulinotropic polypeptide receptor (GIPR), and glucagon-like peptide-1 receptor (GLP-1R). This novel drug has the potential to treat metabolic abnormalities associated with obesity as well as diseases resulting from it due to its distinct mechanism of action. The Phase III trial of this pipeline drug for treating type 2 diabetes mellitus, non-alcoholic fatty liver disease, and obesity started on August 28, 2023. The results of a Phase II clinical trial have demonstrated significant weight reduction in overweight and obese adults. Specifically, the trial reported an average weight loss of 17.5% and 24.4% at 24 and 48 weeks, respectively. CONCLUSIONS These findings hold promise for the development of effective weight loss interventions in this population group. There is a need for more phase III studies to provide sufficient clinical evidence for the effectiveness of retatrutide, as current evidence is limited to phase II studies and has yet to prove its worth in a larger population. Here, we aimed to provide an overview of retatrutide's safety and effectiveness in treating obesity.
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Affiliation(s)
- Manmeet Kaur
- Department of Pharmacology, Kalpana Chawla Government Medical College, Karnal, India
| | - Saurav Misra
- Department of Pharmacology, Kalpana Chawla Government Medical College, Karnal, India.
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Shilleh AH, Viloria K, Broichhagen J, Campbell JE, Hodson DJ. GLP1R and GIPR expression and signaling in pancreatic alpha cells, beta cells and delta cells. Peptides 2024; 175:171179. [PMID: 38360354 DOI: 10.1016/j.peptides.2024.171179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Revised: 02/09/2024] [Accepted: 02/13/2024] [Indexed: 02/17/2024]
Abstract
Glucagon-like peptide-1 receptor (GLP1R) and glucose-dependent insulinotropic polypeptide receptor (GIPR) are transmembrane receptors involved in insulin, glucagon and somatostatin secretion from the pancreatic islet. Therapeutic targeting of GLP1R and GIPR restores blood glucose levels in part by influencing beta cell, alpha cell and delta cell function. Despite the importance of the incretin-mimetics for diabetes therapy, our understanding of GLP1R and GIPR expression patterns and signaling within the islet remain incomplete. Here, we present the evidence for GLP1R and GIPR expression in the major islet cell types, before addressing signaling pathway(s) engaged, as well as their influence on cell survival and function. While GLP1R is largely a beta cell-specific marker within the islet, GIPR is expressed in alpha cells, beta cells, and (possibly) delta cells. GLP1R and GIPR engage Gs-coupled pathways in most settings, although the exact outcome on hormone release depends on paracrine communication and promiscuous signaling. Biased agonism away from beta-arrestin is an emerging concept for improving therapeutic efficacy, and is also relevant for GLP1R/GIPR dual agonism. Lastly, dual agonists exert multiple effects on islet function through GIPR > GLP1R imbalance, increased GLP1R surface expression and cAMP signaling, as well as beneficial alpha cell-beta cell-delta cell crosstalk.
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Affiliation(s)
- Ali H Shilleh
- Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), NIHR Oxford Biomedical Research Centre, Churchill Hospital, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Katrina Viloria
- Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), NIHR Oxford Biomedical Research Centre, Churchill Hospital, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | | | - Jonathan E Campbell
- Duke Molecular Physiology Institute, USA; Department of Medicine, Division of Endocrinology, Duke University, Durham, NC, USA; Department of Pharmacology and Cancer Biology, Duke University, Durham, NC, USA.
| | - David J Hodson
- Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), NIHR Oxford Biomedical Research Centre, Churchill Hospital, Radcliffe Department of Medicine, University of Oxford, Oxford, UK.
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Shi M, Liu C, Qin Y, Yv L, Lu W. α1 and β3 adrenergic receptor-mediated excitatory effects of adrenaline on the caudal neurosecretory system (CNSS) in olive flounder, Paralichthys olivaceus. Gen Comp Endocrinol 2024; 349:114468. [PMID: 38325527 DOI: 10.1016/j.ygcen.2024.114468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 01/14/2024] [Accepted: 02/03/2024] [Indexed: 02/09/2024]
Abstract
Adrenaline is one of the most important neurotransmitters in the central nervous system and is produced during stress. In this study, we investigated the modulatory role of adrenaline and adrenergic receptors on the neuroendocrine Dahlgren cells in the caudal neurosecretory system (CNSS) of olive flounder. Ex vivo electrophysiological recordings revealed that adrenaline significantly increased the firing frequency and altered the firing pattern of Dahlgren cells. Moreover, treatment with adrenaline led to a significant upregulation of ion channels and major hormone secretion genes in CNSS at the mRNA levels. Additionally, treatment with adrenaline resulted in a significantly elevation in the expression levels of α1- and β3-adrenergic receptors. Furthermore, the β3-adrenergic receptor antagonist exerts a significant inhibitory effect on adrenaline-induced enhancement firing activities of Dahlgren cells, whereas the α1-adrenergic receptor antagonist displays a comparatively weaker inhibitory effect. Additionally, the enhanced firing activity induced by adrenaline could be effectively suppressed by both α1- and β3-adrenergic receptor antagonists. Taken together, these findings provide strong evidence in favor of the excitatory effects of adrenaline through α1 and β3 adrenergic receptors in CNSS to stimulate the secretion of stress-related hormones, β3-adrenergic receptor plays a more dominant role in the modulation of firing activities of Dahlgren cells by adrenaline and thereby regulates the stress response in olive flounder.
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Affiliation(s)
- Mengmeng Shi
- National Demonstration Center for Experimental Fisheries Science Education (Shanghai Ocean University), Shanghai 201306, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Shanghai Ocean University), Ministry of Education, Shanghai 201306, China
| | - Cheng Liu
- National Demonstration Center for Experimental Fisheries Science Education (Shanghai Ocean University), Shanghai 201306, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Shanghai Ocean University), Ministry of Education, Shanghai 201306, China
| | - Yeyang Qin
- National Demonstration Center for Experimental Fisheries Science Education (Shanghai Ocean University), Shanghai 201306, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Shanghai Ocean University), Ministry of Education, Shanghai 201306, China
| | - Lin Yv
- National Demonstration Center for Experimental Fisheries Science Education (Shanghai Ocean University), Shanghai 201306, China
| | - Weiqun Lu
- National Demonstration Center for Experimental Fisheries Science Education (Shanghai Ocean University), Shanghai 201306, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources (Shanghai Ocean University), Ministry of Education, Shanghai 201306, China; International Research Center for Marine Biosciences at Shanghai Ocean University, Ministry of Science and Technology, Shanghai 201306, China.
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9
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Chen S, Wang X, Jin Y, Chen X, Song Q, Wei G, Li L. Assessment of Changes in Body Composition After 3 Months of Dulaglutide Treatment. Diabetes Metab Syndr Obes 2024; 17:1301-1308. [PMID: 38505539 PMCID: PMC10949166 DOI: 10.2147/dmso.s443631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 02/29/2024] [Indexed: 03/21/2024] Open
Abstract
Background Changes in body composition accompanied by glucagon-like peptide 1 receptor agonist (GLP-1RA) induced weight loss have drawn much attention. However, fewer studies have reported body composition changes in patients receiving dulaglutide therapy in Chinese population. Methods A total of 70 overweight/obese type 2 diabetes mellitus (T2DM) patients who received dulaglutide therapy were included. Clinical data were collected. Visceral fat area (VFA) and body composition were also measured. Changes in clinical indicators and body composition of patients before and after intervention were also analyzed. Correlation analysis and multiple linear regression model were used to evaluate the association between hemoglobin A1C (HbA1c) and body composition. Results The results showed that body weight (BW), VFA, body fat (BF), lean body mass (LBM), skeletal muscle mass (SMM) and water content were reduced after 3 months dulaglutide intervention. The lean body mass percentage (LBMP) and skeletal muscle mass percentage (SMMP) significantly increased. Moreover, there was no significant difference in bone mineral quality (BMQ) after the intervention. The multiple linear regression model revealed that the % change in BF was independently associated with % change in HbA1c (β = 0.449, t = 3.148, p=0.002). Conclusion These results indicate that dulaglutide intervention does not cause muscle and bone mass loss while inducing weight loss, and % change in BF was independently associated with improved glucose control during dulaglutide therapy. This study offers some positive results to support the clinical application of dulaglutide.
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Affiliation(s)
- Shuqin Chen
- Department of Endocrinology and Metabolism, The First Affiliated Hospital of Ningbo University, Ningbo, People’s Republic of China
| | - Xuepeng Wang
- Department of Infectious Disease, The First Affiliated Hospital of Ningbo University, Ningbo, People’s Republic of China
| | - Yong Jin
- Department of Internal Medicine, Ningbo Yinzhou No.2 Hospital, Ningbo, People’s Republic of China
| | - Xueqin Chen
- Department of Traditional Medicine, The First Affiliated Hospital of Ningbo University, Ningbo, People’s Republic of China
| | - Qifa Song
- Medical Data Center, The First Affiliated Hospital of Ningbo University, Ningbo, People’s Republic of China
| | - Gang Wei
- Beijing Diabetes Institute, Beijing Key Laboratory of Diabetes Research and Care, Department of Endocrinology, Beijing Tongren Hospital, Capital Medical University, Beijing, People’s Republic of China
| | - Li Li
- Department of Endocrinology and Metabolism, The First Affiliated Hospital of Ningbo University, Ningbo, People’s Republic of China
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10
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Gandasi NR, Gao R, Kothegala L, Pearce A, Santos C, Acreman S, Basco D, Benrick A, Chibalina MV, Clark A, Guida C, Harris M, Johnson PRV, Knudsen JG, Ma J, Miranda C, Shigeto M, Tarasov AI, Yeung HY, Thorens B, Asterholm IW, Zhang Q, Ramracheya R, Ladds G, Rorsman P. GLP-1 metabolite GLP-1(9-36) is a systemic inhibitor of mouse and human pancreatic islet glucagon secretion. Diabetologia 2024; 67:528-546. [PMID: 38127123 PMCID: PMC10844371 DOI: 10.1007/s00125-023-06060-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Accepted: 10/18/2023] [Indexed: 12/23/2023]
Abstract
AIMS/HYPOTHESIS Diabetes mellitus is associated with impaired insulin secretion, often aggravated by oversecretion of glucagon. Therapeutic interventions should ideally correct both defects. Glucagon-like peptide 1 (GLP-1) has this capability but exactly how it exerts its glucagonostatic effect remains obscure. Following its release GLP-1 is rapidly degraded from GLP-1(7-36) to GLP-1(9-36). We hypothesised that the metabolite GLP-1(9-36) (previously believed to be biologically inactive) exerts a direct inhibitory effect on glucagon secretion and that this mechanism becomes impaired in diabetes. METHODS We used a combination of glucagon secretion measurements in mouse and human islets (including islets from donors with type 2 diabetes), total internal reflection fluorescence microscopy imaging of secretory granule dynamics, recordings of cytoplasmic Ca2+ and measurements of protein kinase A activity, immunocytochemistry, in vivo physiology and GTP-binding protein dissociation studies to explore how GLP-1 exerts its inhibitory effect on glucagon secretion and the role of the metabolite GLP-1(9-36). RESULTS GLP-1(7-36) inhibited glucagon secretion in isolated islets with an IC50 of 2.5 pmol/l. The effect was particularly strong at low glucose concentrations. The degradation product GLP-1(9-36) shared this capacity. GLP-1(9-36) retained its glucagonostatic effects after genetic/pharmacological inactivation of the GLP-1 receptor. GLP-1(9-36) also potently inhibited glucagon secretion evoked by β-adrenergic stimulation, amino acids and membrane depolarisation. In islet alpha cells, GLP-1(9-36) led to inhibition of Ca2+ entry via voltage-gated Ca2+ channels sensitive to ω-agatoxin, with consequential pertussis-toxin-sensitive depletion of the docked pool of secretory granules, effects that were prevented by the glucagon receptor antagonists REMD2.59 and L-168049. The capacity of GLP-1(9-36) to inhibit glucagon secretion and reduce the number of docked granules was lost in alpha cells from human donors with type 2 diabetes. In vivo, high exogenous concentrations of GLP-1(9-36) (>100 pmol/l) resulted in a small (30%) lowering of circulating glucagon during insulin-induced hypoglycaemia. This effect was abolished by REMD2.59, which promptly increased circulating glucagon by >225% (adjusted for the change in plasma glucose) without affecting pancreatic glucagon content. CONCLUSIONS/INTERPRETATION We conclude that the GLP-1 metabolite GLP-1(9-36) is a systemic inhibitor of glucagon secretion. We propose that the increase in circulating glucagon observed following genetic/pharmacological inactivation of glucagon signalling in mice and in people with type 2 diabetes reflects the removal of GLP-1(9-36)'s glucagonostatic action.
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Affiliation(s)
- Nikhil R Gandasi
- Metabolic Physiology Unit, Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, Gothenburg, Sweden
- Cell Metabolism Lab (GA-08), Department of Developmental Biology and Genetics, Indian Institute of Science, Bangalore, India
| | - Rui Gao
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK
| | - Lakshmi Kothegala
- Metabolic Physiology Unit, Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, Gothenburg, Sweden
| | - Abigail Pearce
- Department of Pharmacology, University of Cambridge, Cambridge, UK
| | - Cristiano Santos
- Metabolic Physiology Unit, Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, Gothenburg, Sweden
| | - Samuel Acreman
- Metabolic Physiology Unit, Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, Gothenburg, Sweden
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK
| | - Davide Basco
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
| | - Anna Benrick
- Metabolic Physiology Unit, Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, Gothenburg, Sweden
| | - Margarita V Chibalina
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK
| | - Anne Clark
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK
| | - Claudia Guida
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK
| | - Matthew Harris
- Department of Pharmacology, University of Cambridge, Cambridge, UK
| | - Paul R V Johnson
- Nuffield Department of Surgical Sciences, John Radcliffe Hospital, Oxford, UK
- Biomedical Research Centre, Oxford National Institute for Health Research, Churchill Hospital, Oxford, UK
| | - Jakob G Knudsen
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Jinfang Ma
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK
| | - Caroline Miranda
- Metabolic Physiology Unit, Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, Gothenburg, Sweden
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK
| | - Makoto Shigeto
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK
| | - Andrei I Tarasov
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK
- School of Biomedical Sciences, University of Ulster, Coleraine, Northern Ireland, UK
| | - Ho Yan Yeung
- Department of Pharmacology, University of Cambridge, Cambridge, UK
| | - Bernard Thorens
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
| | - Ingrid W Asterholm
- Metabolic Physiology Unit, Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, Gothenburg, Sweden
| | - Quan Zhang
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK
| | - Reshma Ramracheya
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK
| | - Graham Ladds
- Department of Pharmacology, University of Cambridge, Cambridge, UK
| | - Patrik Rorsman
- Metabolic Physiology Unit, Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, Gothenburg, Sweden.
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK.
- Biomedical Research Centre, Oxford National Institute for Health Research, Churchill Hospital, Oxford, UK.
- School of Biomedical Sciences, University of Ulster, Coleraine, Northern Ireland, UK.
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11
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Tian H, Chang M, Lyu Y, Dong N, Yu N, Yin T, Zhang Y, He H, Gou J, Tang X. Intramuscular injection of palmitic acid-conjugated Exendin-4 loaded multivesicular liposomes for long-acting and improving in-situ stability. Expert Opin Drug Deliv 2024; 21:169-185. [PMID: 38224039 DOI: 10.1080/17425247.2024.2305110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 01/09/2024] [Indexed: 01/16/2024]
Abstract
BACKGROUND Exendin-4 (Ex4) is a promising drug for diabetes mellitus with a half-life of 2.4 h in human bodies. Besides, the Ex4 formulations currently employed in the clinic or under development have problems pertaining to stability. In this study, palmitic acid-modified Ex4 (Pal-Ex4) was prepared and purified to extend the half-life of Ex4. In addition, Pal-Ex4-MVLs were further designed and optimized as a long-acting delivery system for intramuscular injection. METHODS Pal-Ex4 was encapsulated within multivesicular liposomes (MVLs) via a two-step double emulsification process. The formulated products were then assessed for their vesicle size, encapsulation efficiency, and in vitro and in vivo. RESULTS Pal-Ex4-MVLs with a notable encapsulation efficiency of 99.18% were successfully prepared. Pal-Ex4-MVLs, administered via a single intramuscular injection in Sprague-Dawley rats, sustained stable plasma concentrations for 168 h, presenting extended half-life (77.28 ± 12.919 h) and enhanced relative bioavailability (664.18%). MVLs protected Ex4 through providing stable retention and slow release. This approach considerably improved the in-situ stability of the drug for intramuscular administration. CONCLUSIONS The combination of palmitic acid modification process with MVLs provides dual protection for Ex4 and can be a promising strategy for other hydrophilic protein/polypeptide-loaded sustained-release delivery systems with high drug bioactivity.
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Affiliation(s)
- Huixian Tian
- Department of Pharmaceutics, School of Pharmacy, Shenyang Pharmaceutical University, Shenyang, Liaoning, PR China
| | - Minsi Chang
- Department of Pharmaceutics, School of Pharmacy, Shenyang Pharmaceutical University, Shenyang, Liaoning, PR China
| | - Yanlin Lyu
- Department of Pharmaceutics, School of Pharmacy, Shenyang Pharmaceutical University, Shenyang, Liaoning, PR China
| | - Nan Dong
- Department of Pharmaceutics, School of Pharmacy, Shenyang Pharmaceutical University, Shenyang, Liaoning, PR China
| | - Nini Yu
- Department of Pharmaceutics, School of Pharmacy, Shenyang Pharmaceutical University, Shenyang, Liaoning, PR China
| | - Tian Yin
- School of Functional Food and Wine, Shenyang Pharmaceutical University, Shenyang, Liaoning, PR China
| | - Yu Zhang
- Department of Pharmaceutics, School of Pharmacy, Shenyang Pharmaceutical University, Shenyang, Liaoning, PR China
| | - Haibing He
- Department of Pharmaceutics, School of Pharmacy, Shenyang Pharmaceutical University, Shenyang, Liaoning, PR China
| | - Jingxin Gou
- Department of Pharmaceutics, School of Pharmacy, Shenyang Pharmaceutical University, Shenyang, Liaoning, PR China
| | - Xing Tang
- Department of Pharmaceutics, School of Pharmacy, Shenyang Pharmaceutical University, Shenyang, Liaoning, PR China
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12
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Bany Bakar R, Reimann F, Gribble FM. The intestine as an endocrine organ and the role of gut hormones in metabolic regulation. Nat Rev Gastroenterol Hepatol 2023; 20:784-796. [PMID: 37626258 DOI: 10.1038/s41575-023-00830-y] [Citation(s) in RCA: 17] [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: 07/25/2023] [Indexed: 08/27/2023]
Abstract
Gut hormones orchestrate pivotal physiological processes in multiple metabolically active tissues, including the pancreas, liver, adipose tissue, gut and central nervous system, making them attractive therapeutic targets in the treatment of obesity and type 2 diabetes mellitus. Most gut hormones are derived from enteroendocrine cells, but bioactive peptides that are derived from other intestinal epithelial cell types have also been implicated in metabolic regulation and can be considered gut hormones. A deeper understanding of the complex inter-organ crosstalk mediated by the intestinal endocrine system is a prerequisite for designing more effective drugs that are based on or target gut hormones and their receptors, and extending their therapeutic potential beyond obesity and diabetes mellitus. In this Review, we present an overview of gut hormones that are involved in the regulation of metabolism and discuss their action in the gastrointestinal system and beyond.
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Affiliation(s)
- Rula Bany Bakar
- Wellcome Trust-MRC Institute of Metabolic Science Metabolic Research Laboratories, University of Cambridge, Cambridge, UK
| | - Frank Reimann
- Wellcome Trust-MRC Institute of Metabolic Science Metabolic Research Laboratories, University of Cambridge, Cambridge, UK
| | - Fiona M Gribble
- Wellcome Trust-MRC Institute of Metabolic Science Metabolic Research Laboratories, University of Cambridge, Cambridge, UK.
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13
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Chen D, Rehfeld JF, Watts AG, Rorsman P, Gundlach AL. History of key regulatory peptide systems and perspectives for future research. J Neuroendocrinol 2023; 35:e13251. [PMID: 37053148 DOI: 10.1111/jne.13251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 02/10/2023] [Accepted: 02/26/2023] [Indexed: 03/06/2023]
Abstract
Throughout the 20th Century, regulatory peptide discovery advanced from the identification of gut hormones to the extraction and characterization of hypothalamic hypophysiotropic factors, and to the isolation and cloning of multiple brain neuropeptides. These discoveries were followed by the discovery of G-protein-coupled and other membrane receptors for these peptides. Subsequently, the systems physiology associated with some of these multiple regulatory peptides and receptors has been comprehensively elucidated and has led to improved therapeutics and diagnostics and their approval by the US Food and Drug Administration. In light of this wealth of information and further potential, it is truly a time of renaissance for regulatory peptides. In this perspective, we review what we have learned from the pioneers in exemplified fields of gut peptides, such as cholecystokinin, enterochromaffin-like-cell peptides, and glucagon, from the trailblazing studies on the key stress hormone, corticotropin-releasing factor, as well as from more recently characterized relaxin-family peptides and receptors. The historical viewpoints are based on our understanding of these topics in light of the earliest phases of research and on subsequent studies and the evolution of knowledge, aiming to sharpen our vision of the current state-of-the-art and those studies that should be prioritized in the future.
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Affiliation(s)
- Duan Chen
- Department of Clinical and Molecular Medicine, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - Jens F Rehfeld
- Department of Clinical Biochemistry, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Alan G Watts
- Department of Biological Sciences, Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, California, USA
| | - Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Andrew L Gundlach
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, VIC, Australia
- Florey Department of Neuroscience and Mental Health and Department of Anatomy and Physiology, The University of Melbourne, Melbourne, VIC, Australia
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14
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Knuth ER, Foster HR, Jin E, Merrins MJ. Leucine suppresses glucagon secretion from pancreatic islets by directly modulating α-cell cAMP. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.31.551113. [PMID: 37577685 PMCID: PMC10418066 DOI: 10.1101/2023.07.31.551113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
Objective Pancreatic islets are nutrient sensors that regulate organismal blood glucose homeostasis. Glucagon release from the pancreatic α-cell is important under fasted, fed, and hypoglycemic conditions, yet metabolic regulation of α-cells remains poorly understood. Here, we identified a previously unexplored role for physiological levels of leucine, which is classically regarded as a β-cell fuel, in the intrinsic regulation of α-cell glucagon release. Methods GcgCreERT:CAMPER and GcgCreERT:GCaMP6s mice were generated to perform dynamic, high-throughput functional measurements of α-cell cAMP and Ca2+ within the intact islet. Islet perifusion assays were used for simultaneous, time-resolved measurements of glucagon and insulin release from mouse and human islets. The effects of leucine were compared with glucose and the mitochondrial fuels 2-aminobicyclo(2,2,1)heptane-2-carboxylic acid (BCH, non-metabolized leucine analog that activates glutamate dehydrogenase), α-ketoisocaproate (KIC, leucine metabolite), and methyl-succinate (complex II fuel). CYN154806 (Sstr2 antagonist), diazoxide (KATP activator, which prevents Ca2+-dependent exocytosis from α, β, and δ-cells), and dispersed α-cells were used to inhibit islet paracrine signaling and identify α-cell intrinsic effects. Results Mimicking the effect of glucose, leucine strongly suppressed amino acid-stimulated glucagon secretion. Mechanistically, leucine dose-dependently reduced α-cell cAMP at physiological concentrations, with an IC50 of 57, 440, and 1162 μM at 2, 6, and 10 mM glucose, without affecting α-cell Ca2+. Leucine also reduced α-cell cAMP in islets treated with Sstr2 antagonist or diazoxide, as well as dispersed α-cells, indicating an α-cell intrinsic effect. The effect of leucine was matched by KIC and the glutamate dehydrogenase activator BCH, but not methyl-succinate, indicating a dependence on mitochondrial anaplerosis. Glucose, which stimulates anaplerosis via pyruvate carboxylase, had the same suppressive effect on α-cell cAMP but with lower potency. Similarly to mouse islets, leucine suppressed glucagon secretion from human islets under hypoglycemic conditions. Conclusions These findings highlight an important role for physiological levels of leucine in the metabolic regulation of α-cell cAMP and glucagon secretion. Leucine functions primarily through an α-cell intrinsic effect that is dependent on glutamate dehydrogenase, in addition to the well-established α-cell regulation by β/δ-cell paracrine signaling. Our results suggest that mitochondrial anaplerosis-cataplerosis facilitates the glucagonostatic effect of both leucine and glucose, which cooperatively suppress α-cell tone by reducing cAMP.
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Affiliation(s)
- Emily R. Knuth
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Hannah R. Foster
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Erli Jin
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Matthew J. Merrins
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin-Madison, Madison, WI 53705, USA
- William S. Middleton Memorial Veterans Hospital, Madison, WI 53705, USA
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15
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Hamilton A, Eliasson L, Knudsen JG. Amino acids and the changing face of the α-cell. Peptides 2023:171039. [PMID: 37295651 DOI: 10.1016/j.peptides.2023.171039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 05/31/2023] [Accepted: 06/05/2023] [Indexed: 06/12/2023]
Abstract
Glucagon has long been defined by its glucogenic action and as a result α-cells have been characterised based largely on their interaction with glucose. Recent findings have challenged this preconception, bringing to the fore the significant role glucagon plays in amino acid breakdown and underlining the importance of amino acids in glucagon secretion. The challenge that remains is defining the mechanism that underlie these effects - understanding which amino acids are most important, how they act on the α-cell and how their actions integrate with other fuels such as glucose and fatty acids. This review will describe the current relationship between amino acids and glucagon and how we can use this knowledge to redefine the α-cell.
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Affiliation(s)
- Alexander Hamilton
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Denmark; Department of Clinical Sciences in Malmö, Islet Cell Exocytosis, Lund University Diabetes Centre, Lund University, Malmö, Sweden.
| | - Lena Eliasson
- Department of Clinical Sciences in Malmö, Islet Cell Exocytosis, Lund University Diabetes Centre, Lund University, Malmö, Sweden.
| | - Jakob G Knudsen
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Denmark.
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16
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Berman C, Vidmar AP, Chao LC. Glucagon-like Peptide-1 Receptor Agonists for the Treatment of Type 2 Diabetes in Youth. TOUCHREVIEWS IN ENDOCRINOLOGY 2023; 19:38-45. [PMID: 37313232 PMCID: PMC10258616 DOI: 10.17925/ee.2023.19.1.38] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 04/20/2023] [Indexed: 06/15/2023]
Abstract
Glucagon-like peptide-1 receptor agonists (GLP-1RAs) have gained traction for the management of type 2 diabetes and obesity. Unlike several classes of antidiabetic medications that contribute to weight gain, GLP-1RAs not only reduce haemoglobin A1c, but also promote weight loss. While there is a large body of evidence supporting its safety and efficacy in adults, paediatric clinical trial data have only emerged in recent years. This review will discuss the limited treatment options for paediatric type 2 diabetes and the mechanism of action of GLP-1RAs as it pertains to physiological pathways relevant for type 2 diabetes, obesity and their related comorbidities. The outcomes of paediatric trials evaluating liraglutide, exenatide, semaglutide and dulaglutide in paediatric type 2 diabetes and obesity will be closely examined, including differences compared with adult studies. Finally, potential barriers and strategies to expanding GLP-1RA access in adolescents will be discussed. Future studies are needed to determine if the cardio-and renal-protective benefits of GLP-1RAs apply to youth-onset type 2 diabetes.
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Affiliation(s)
- Casey Berman
- Division of Endocrinology, Department of Pediatrics, Children’s Hospital Los Angeles, Los Angeles, CA, USA
| | - Alaina P Vidmar
- Division of Endocrinology, Department of Pediatrics, Children’s Hospital Los Angeles, Los Angeles, CA, USA
- Keck School of Medicine of University of Southern California, Los Angeles, CA, USA
| | - Lily C Chao
- Division of Endocrinology, Department of Pediatrics, Children’s Hospital Los Angeles, Los Angeles, CA, USA
- Keck School of Medicine of University of Southern California, Los Angeles, CA, USA
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17
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Lafferty RA, Flatt PR, Irwin N. GLP-1/GIP analogues: potential impact in the landscape of obesity pharmacotherapy. Expert Opin Pharmacother 2023; 24:587-597. [PMID: 36927378 DOI: 10.1080/14656566.2023.2192865] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023]
Abstract
INTRODUCTION : Obesity is recognised as a major healthcare challenge. Following years of slow progress in discovery of safe, effective therapies for weight management, recent approval of the glucagon-like peptide 1 receptor (GLP-1R) mimetics, liraglutide and semaglutide, for obesity has generated considerable excitement. It is anticipated these agents will pave the way for application of tirzepatide, a highly effective glucose-dependent insulinotropic polypeptide receptor (GIPR), GLP-1R co-agonist recently approved for management of type 2 diabetes mellitus. AREAS COVERED : Following promising weight loss in obese individuals in Phase III clinical trials, liraglutide and semaglutide were approved for weight management without diabetes. Tirzepatide has attained Fast Track designation for obesity management by the US Food and Drug Association. This narrative review summarises experimental, preclinical and clinical data for these agents and related GLP-1R/GIPR co-agonists, prioritising clinical research published within the last 10 years where possible. EXPERT OPINION : GLP-1R mimetics are often discontinued within 24-months, owing to gastrointestinal side-effects, meaning long-term application of these agents in obesity is questioned. Combined GIPR/GLP-1R agonism appears to induce fewer side-effects, indicating GLP-1R/GIPR co-agonists may be more suitable for enduring obesity management. After years of debate, this GIPR-biased GLP-1R/GIPR co-agonist highlights the therapeutic promise of including GIPR modulation for diabetes and obesity therapy.
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Affiliation(s)
- Ryan A Lafferty
- Diabetes Research Centre, Ulster University, Coleraine, Northern Ireland, BT52 1SA, UK
| | - Peter R Flatt
- Diabetes Research Centre, Ulster University, Coleraine, Northern Ireland, BT52 1SA, UK
| | - Nigel Irwin
- Diabetes Research Centre, Ulster University, Coleraine, Northern Ireland, BT52 1SA, UK
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18
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Abstract
Plasma glucose is tightly regulated via the secretion of the two glucose-regulating hormones insulin and glucagon. Situated next to the insulin-secreting β-cells, the α-cells produce and secrete glucagon-one of the body's few blood glucose-increasing hormones. Diabetes is a bihormonal disorder, resulting from both inadequate insulin secretion and dysregulation of glucagon. The year 2023 marks the 100th anniversary of the discovery of glucagon, making it particularly timely to highlight the roles of this systemic metabolic messenger in health and disease.
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Affiliation(s)
- Patrick E MacDonald
- Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada
- Department of Pharmacology, University of Alberta, Edmonton, AB, Canada
| | - Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford, UK.
- Metabolic Physiology, Institute of Neuroscience and Physiology, University of Göteborg, Gothenburg, Sweden.
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19
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Pixner T, Stummer N, Schneider AM, Lukas A, Gramlinger K, Julian V, Thivel D, Mörwald K, Mangge H, Dalus C, Aigner E, Furthner D, Weghuber D, Maruszczak K. The relationship between glucose and the liver-alpha cell axis - A systematic review. Front Endocrinol (Lausanne) 2023; 13:1061682. [PMID: 36686477 PMCID: PMC9849557 DOI: 10.3389/fendo.2022.1061682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Accepted: 12/13/2022] [Indexed: 01/06/2023] Open
Abstract
Until recently, glucagon was considered a mere antagonist to insulin, protecting the body from hypoglycemia. This notion changed with the discovery of the liver-alpha cell axis (LACA) as a feedback loop. The LACA describes how glucagon secretion and pancreatic alpha cell proliferation are stimulated by circulating amino acids. Glucagon in turn leads to an upregulation of amino acid metabolism and ureagenesis in the liver. Several increasingly common diseases (e.g., non-alcoholic fatty liver disease, type 2 diabetes, obesity) disrupt this feedback loop. It is important for clinicians and researchers alike to understand the liver-alpha cell axis and the metabolic sequelae of these diseases. While most of previous studies have focused on fasting concentrations of glucagon and amino acids, there is limited knowledge of their dynamics after glucose administration. The authors of this systematic review applied PRISMA guidelines and conducted PubMed searches to provide results of 8078 articles (screened and if relevant, studied in full). This systematic review aims to provide better insight into the LACA and its mediators (amino acids and glucagon), focusing on the relationship between glucose and the LACA in adult and pediatric subjects.
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Affiliation(s)
- Thomas Pixner
- Department of Pediatric and Adolescent Medicine, Salzkammergutklinikum Voecklabruck, Voecklabruck, Austria
- Obesity Research Unit, Paracelsus Medical University, Salzburg, Austria
| | - Nathalie Stummer
- Obesity Research Unit, Paracelsus Medical University, Salzburg, Austria
- Department of Pediatrics, Paracelsus Medical University, Salzburg, Austria
| | - Anna Maria Schneider
- Obesity Research Unit, Paracelsus Medical University, Salzburg, Austria
- Department of Pediatrics, Paracelsus Medical University, Salzburg, Austria
| | - Andreas Lukas
- Department of Pediatric and Adolescent Medicine, Salzkammergutklinikum Voecklabruck, Voecklabruck, Austria
- Obesity Research Unit, Paracelsus Medical University, Salzburg, Austria
| | - Karin Gramlinger
- Department of Pediatric and Adolescent Medicine, Salzkammergutklinikum Voecklabruck, Voecklabruck, Austria
| | - Valérie Julian
- Department of Sport Medicine and Functional Explorations, Diet and Musculoskeletal Health Team, Human Nutrition Research Center (CRNH), INRA, University Hospital of Clermont-Ferrand, University of Clermont Auvergne, Clermont-Ferrand, France
| | - David Thivel
- Laboratory of Metabolic Adaptations to Exercise under Physiological and Pathological Conditions (AME2P), University of Clermont Auvergne, Clermont-Ferrand, France
| | - Katharina Mörwald
- Obesity Research Unit, Paracelsus Medical University, Salzburg, Austria
- Department of Pediatrics, Paracelsus Medical University, Salzburg, Austria
| | - Harald Mangge
- Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Graz, Graz, Austria
| | - Christopher Dalus
- Obesity Research Unit, Paracelsus Medical University, Salzburg, Austria
- Department of Pediatrics, Paracelsus Medical University, Salzburg, Austria
| | - Elmar Aigner
- Obesity Research Unit, Paracelsus Medical University, Salzburg, Austria
- First Department of Medicine, Paracelsus Medical University, Salzburg, Austria
| | - Dieter Furthner
- Department of Pediatric and Adolescent Medicine, Salzkammergutklinikum Voecklabruck, Voecklabruck, Austria
- Obesity Research Unit, Paracelsus Medical University, Salzburg, Austria
| | - Daniel Weghuber
- Obesity Research Unit, Paracelsus Medical University, Salzburg, Austria
- Department of Pediatrics, Paracelsus Medical University, Salzburg, Austria
| | - Katharina Maruszczak
- Obesity Research Unit, Paracelsus Medical University, Salzburg, Austria
- Department of Pediatrics, Paracelsus Medical University, Salzburg, Austria
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20
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Klempel N, Thomas K, Conlon JM, Flatt PR, Irwin N. Alpha-cells and therapy of diabetes: Inhibition, antagonism or death? Peptides 2022; 157:170877. [PMID: 36108978 DOI: 10.1016/j.peptides.2022.170877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 09/06/2022] [Accepted: 09/08/2022] [Indexed: 11/22/2022]
Abstract
Absolute or relative hyperglucagonaemia is a characteristic of both Type 1 and Type 2 diabetes, resulting in fasting hyperglycaemia due in part to increased hepatic glucose production and lack of postprandial suppression of circulating glucagon concentrations. Consequently, therapeutics that target glucagon secretion or biological action may be effective antidiabetic agents. In this regard, specific glucagon receptor (GCGR) antagonists have been developed that exhibit impressive glucose-lowering actions, but unfortunately may cause off-target adverse effects in humans. Further to this, several currently approved antidiabetic agents, including GLP-1 mimetics, DPP-4 inhibitors, metformin, sulphonylureas and pramlintide likely exert part of their glucose homeostatic actions through direct or indirect inhibition of GCGR signalling. In addition to agents that inhibit the release of glucagon, compounds that enhance the transdifferentiation of glucagon secreting alpha-cells towards an insulin positive beta-cell phenotype could also help curb excess glucagon secretion in diabetes. Use of alpha-cell toxins represents another possible strategy to address hyperglucagonaemia in diabetes. In that respect, research from the 1920 s with diguanides such as synthalin A demonstrated effective glucose-lowering with alpha-cell ablation in both animal models and humans with diabetes. However, further clinical use of synthalin A was curtailed due its adverse effects and the increased availability of insulin. Overall, these observations with therapeutics that directly target alpha-cells, or GCGR signaling, highlight a largely untapped potential for diabetes therapy that merits further detailed consideration.
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Affiliation(s)
- Natalie Klempel
- Diabetes Research Centre, Biomedical Sciences Research Institute, Ulster University, Cromore Road, Coleraine, Northern Ireland BT52 1SA, UK
| | - Keith Thomas
- Diabetes Research Centre, Biomedical Sciences Research Institute, Ulster University, Cromore Road, Coleraine, Northern Ireland BT52 1SA, UK
| | - J Michael Conlon
- Diabetes Research Centre, Biomedical Sciences Research Institute, Ulster University, Cromore Road, Coleraine, Northern Ireland BT52 1SA, UK
| | - Peter R Flatt
- Diabetes Research Centre, Biomedical Sciences Research Institute, Ulster University, Cromore Road, Coleraine, Northern Ireland BT52 1SA, UK
| | - Nigel Irwin
- Diabetes Research Centre, Biomedical Sciences Research Institute, Ulster University, Cromore Road, Coleraine, Northern Ireland BT52 1SA, UK.
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21
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Zaborska KE, Jordan KL, Thorson AS, Dadi PK, Schaub CM, Nakhe AY, Dickerson MT, Lynch JC, Weiss AJ, Dobson JR, Jacobson DA. Liraglutide increases islet Ca 2+ oscillation frequency and insulin secretion by activating hyperpolarization-activated cyclic nucleotide-gated channels. Diabetes Obes Metab 2022; 24:1741-1752. [PMID: 35546791 PMCID: PMC9843726 DOI: 10.1111/dom.14747] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 04/28/2022] [Accepted: 04/29/2022] [Indexed: 01/19/2023]
Abstract
AIM To determine whether hyperpolarization-activated cyclic nucleotide-gated (HCN) channels impact glucagon-like peptide-1 (GLP-1) receptor (GLP-1R) modulation of islet Ca2+ handling and insulin secretion. METHODS The impact of liraglutide (GLP-1 analogue) on islet Ca2+ handling, HCN currents and insulin secretion was monitored with fluorescence microscopy, electrophysiology and enzyme immunoassays, respectively. Furthermore, liraglutide-mediated β-to-δ-cell cross-communication was assessed following selective ablation of either mouse islet δ or β cells. RESULTS Liraglutide increased β-cell Ca2+ oscillation frequency in mouse and human islets under stimulatory glucose conditions. This was dependent in part on liraglutide activation of HCN channels, which also enhanced insulin secretion. Similarly, liraglutide activation of HCN channels also increased β-cell Ca2+ oscillation frequency in islets from rodents exposed to a diabetogenic diet. Interestingly, liraglutide accelerated Ca2+ oscillations in a majority of islet δ cells, which showed synchronized Ca2+ oscillations equivalent to β cells; therefore, we assessed if either cell type was driving this liraglutide-mediated islet Ca2+ response. Although δ-cell loss did not impact liraglutide-mediated increase in β-cell Ca2+ oscillation frequency, β-cell ablation attenuated liraglutide-facilitated acceleration of δ-cell Ca2+ oscillations. CONCLUSION The data presented here show that liraglutide-induced stimulation of islet HCN channels augments Ca2+ oscillation frequency. As insulin secretion oscillates with β-cell Ca2+ , these findings have important implications for pulsatile insulin secretion that is probably enhanced by liraglutide activation of HCN channels and therapeutics that target GLP-1Rs for treating diabetes. Furthermore, these studies suggest that liraglutide as well as GLP-1-based therapies enhance δ-cell Ca2+ oscillation frequency and somatostatin secretion kinetics in a β-cell-dependent manner.
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Affiliation(s)
- Karolina E Zaborska
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Kelli L Jordan
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Ariel S Thorson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Prasanna K Dadi
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Charles M Schaub
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Arya Y Nakhe
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Matthew T Dickerson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Joshua C Lynch
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Adam J Weiss
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Jordyn R Dobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - David A Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
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22
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Sun L, Zheng ZM, Shao CS, Zhang ZY, Li MW, Wang L, Wang H, Zhao GH, Wang P. Rational Design by Structural Biology of Industrializable, Long-Acting Antihyperglycemic GLP-1 Receptor Agonists. Pharmaceuticals (Basel) 2022; 15:ph15060740. [PMID: 35745659 PMCID: PMC9230455 DOI: 10.3390/ph15060740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 05/19/2022] [Accepted: 05/20/2022] [Indexed: 02/01/2023] Open
Abstract
Glucagon-like peptide-1 (GLP-1) is easily degraded by dipeptidyl peptidase-4 (DPP-4) in the human body, limiting its therapeutic effect on type II diabetes. Therefore, improving GLP-1 receptor agonist (GLP-1RA) stability is a major obstacle for drug development. We analyzed human GLP-1, DPP-4, and GLP-1 receptor structures and designed three GLP-1RAs, which were introduced into fusion protein fragments and changed in the overall conformation. This modification effectively prevented GLP-1RAs from entering the DPP-4 active center without affecting GLP-1RAs’ ability to bind to GLP-1R, the new GLP-1RA hypoglycemic effect lasting for >24 h. Through molecular modeling, molecular dynamics calculation, and simulation, possible tertiary structure models of GLP-1RAs were obtained; molecular docking with DPP-4 and GLP-1R showed access to the fusion protein. The overall conformational change of GLP-1RAs prevented DPP-4 binding, without affecting GLP-1RAs’ affinity to GLP-1R. This study provides important drug design ideas for GLP-1RA development and a new example for application of structural biology-based protein design in drug development.
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Affiliation(s)
- Lei Sun
- Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences (CAS), Hefei 230031, China; (L.S.); (C.-S.S.); (L.W.); (H.W.); (G.-H.Z.)
- Science Island Branch of Graduate School, University of Science and Technology of China, Hefei 230026, China
| | - Zhi-Ming Zheng
- Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences (CAS), Hefei 230031, China; (L.S.); (C.-S.S.); (L.W.); (H.W.); (G.-H.Z.)
- Correspondence: (Z.-M.Z.); (P.W.); Tel./Fax: +86-551-65593148 (Z.-M.Z.); +86-551-65593145 (P.W.)
| | - Chang-Sheng Shao
- Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences (CAS), Hefei 230031, China; (L.S.); (C.-S.S.); (L.W.); (H.W.); (G.-H.Z.)
| | - Zhi-Yong Zhang
- MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, National Science Center for Physical Sciences at Microscale, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230022, China; (Z.-Y.Z.); (M.-W.L.)
| | - Ming-Wei Li
- MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, National Science Center for Physical Sciences at Microscale, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230022, China; (Z.-Y.Z.); (M.-W.L.)
| | - Li Wang
- Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences (CAS), Hefei 230031, China; (L.S.); (C.-S.S.); (L.W.); (H.W.); (G.-H.Z.)
| | - Han Wang
- Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences (CAS), Hefei 230031, China; (L.S.); (C.-S.S.); (L.W.); (H.W.); (G.-H.Z.)
| | - Gen-Hai Zhao
- Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences (CAS), Hefei 230031, China; (L.S.); (C.-S.S.); (L.W.); (H.W.); (G.-H.Z.)
| | - Peng Wang
- Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences (CAS), Hefei 230031, China; (L.S.); (C.-S.S.); (L.W.); (H.W.); (G.-H.Z.)
- Science Island Branch of Graduate School, University of Science and Technology of China, Hefei 230026, China
- Correspondence: (Z.-M.Z.); (P.W.); Tel./Fax: +86-551-65593148 (Z.-M.Z.); +86-551-65593145 (P.W.)
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23
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Guccio N, Gribble FM, Reimann F. Glucose-Dependent Insulinotropic Polypeptide-A Postprandial Hormone with Unharnessed Metabolic Potential. Annu Rev Nutr 2022; 42:21-44. [PMID: 35609956 DOI: 10.1146/annurev-nutr-062320-113625] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Glucose-dependent insulinotropic polypeptide (GIP) is released from the upper small intestine in response to food intake and contributes to the postprandial control of nutrient disposition, including of sugars and fats. Long neglected as a potential therapeutic target, the GIPR axis has received increasing interest recently, with the emerging data demonstrating the metabolically favorable outcomes of adding GIPR agonism to GLP-1 receptor agonists in people with type 2 diabetes and obesity. This review examines the physiology of the GIP axis, from the mechanisms underlying GIP secretion from the intestine to its action on target tissues and therapeutic development. Expected final online publication date for the Annual Review of Nutrition, Volume 42 is August 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Nunzio Guccio
- MRC Metabolic Diseases Unit, Wellcome Trust/MRC Institute of Metabolic Science, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom; ,
| | - Fiona M Gribble
- MRC Metabolic Diseases Unit, Wellcome Trust/MRC Institute of Metabolic Science, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom; ,
| | - Frank Reimann
- MRC Metabolic Diseases Unit, Wellcome Trust/MRC Institute of Metabolic Science, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom; ,
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24
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Wendt A, Eliasson L. Pancreatic alpha cells and glucagon secretion: Novel functions and targets in glucose homeostasis. Curr Opin Pharmacol 2022; 63:102199. [PMID: 35245797 DOI: 10.1016/j.coph.2022.102199] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Revised: 01/25/2022] [Accepted: 01/31/2022] [Indexed: 11/16/2022]
Abstract
Diabetes is the result of dysregulation of both insulin and glucagon. Still, insulin has attracted much more attention than glucagon. Glucagon is released from alpha cells in the islets of Langerhans in response to low glucose and certain amino acids. Drugs with the primary aim of targeting glucagon signalling are scarce. However, glucagon is often administered to counteract severe hypoglycaemia, and commonly used diabetes medications such as GLP-1 analogues, sulfonylureas and SGLT2-inhibitors also affect alpha cells. Indeed, there are physiological and developmental similarities between the alpha cell and the insulin-secreting beta cell and new data confirm that alpha cells can be converted into insulin-secreting cells. These aspects and attributes, the need to find novel therapies targeting the alpha cell and more are considered in this review.
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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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25
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Andersen DB, Holst JJ. Peptides in the regulation of glucagon secretion. Peptides 2022; 148:170683. [PMID: 34748791 DOI: 10.1016/j.peptides.2021.170683] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 10/21/2021] [Accepted: 11/02/2021] [Indexed: 02/06/2023]
Abstract
Glucose homeostasis is maintained by the glucoregulatory hormones, glucagon, insulin and somatostatin, secreted from the islets of Langerhans. Glucagon is the body's most important anti-hypoglycemic hormone, mobilizing glucose from glycogen stores in the liver in response to fasting, thus maintaining plasma glucose levels within healthy limits. Glucagon secretion is regulated by both circulating nutrients, hormones and neuronal inputs. Hormones that may regulate glucagon secretion include locally produced insulin and somatostatin, but also urocortin-3, amylin and pancreatic polypeptide, and from outside the pancreas glucagon-like peptide-1 and 2, peptide tyrosine tyrosine and oxyntomodulin, glucose-dependent insulinotropic polypeptide, neurotensin and ghrelin, as well as the hypothalamic hormones arginine-vasopressin and oxytocin, and calcitonin from the thyroid. Each of these hormones have distinct effects, ranging from regulating blood glucose, to regulating appetite, stomach emptying rate and intestinal motility, which makes them interesting targets for treating metabolic diseases. Awareness regarding the potential effects of the hormones on glucagon secretion is important since secretory abnormalities could manifest as hyperglycemia or even lethal hypoglycemia. Here, we review the effects of each individual hormone on glucagon secretion, their interplay, and how treatments aimed at modulating the plasma levels of these hormones may also influence glucagon secretion and glycemic control.
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Affiliation(s)
- Daniel B Andersen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Panum Institute, Blegdamsvej 3B, 2200, Copenhagen N, Denmark; Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Jens J Holst
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Panum Institute, Blegdamsvej 3B, 2200, Copenhagen N, Denmark; Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark.
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26
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Dai XQ, Camunas-Soler J, Briant LJB, Dos Santos T, Spigelman AF, Walker EM, Arrojo E Drigo R, Bautista A, Jones RC, Avrahami D, Lyon J, Nie A, Smith N, Zhang Y, Johnson J, Manning Fox JE, Michelakis ED, Light PE, Kaestner KH, Kim SK, Rorsman P, Stein RW, Quake SR, MacDonald PE. Heterogenous impairment of α cell function in type 2 diabetes is linked to cell maturation state. Cell Metab 2022; 34:256-268.e5. [PMID: 35108513 PMCID: PMC8852281 DOI: 10.1016/j.cmet.2021.12.021] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 10/08/2021] [Accepted: 12/22/2021] [Indexed: 02/03/2023]
Abstract
In diabetes, glucagon secretion from pancreatic α cells is dysregulated. The underlying mechanisms, and whether dysfunction occurs uniformly among cells, remain unclear. We examined α cells from human donors and mice using electrophysiological, transcriptomic, and computational approaches. Rising glucose suppresses α cell exocytosis by reducing P/Q-type Ca2+ channel activity, and this is disrupted in type 2 diabetes (T2D). Upon high-fat feeding of mice, α cells shift toward a "β cell-like" electrophysiological profile in concert with indications of impaired identity. In human α cells we identified links between cell membrane properties and cell surface signaling receptors, mitochondrial respiratory chain complex assembly, and cell maturation. Cell-type classification using machine learning of electrophysiology data demonstrated a heterogenous loss of "electrophysiologic identity" in α cells from donors with type 2 diabetes. Indeed, a subset of α cells with impaired exocytosis is defined by an enrichment in progenitor and lineage markers and upregulation of an immature transcriptomic phenotype, suggesting important links between α cell maturation state and dysfunction.
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Affiliation(s)
- Xiao-Qing Dai
- Department of Pharmacology, University of Alberta, Edmonton, AB T6G2R3, Canada; Alberta Diabetes Institute, University of Alberta, Edmonton, AB T6G2R3, Canada
| | - Joan Camunas-Soler
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA; Chan Zuckerberg Biohub, San Francisco, CA 94518, USA
| | - Linford J B Briant
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, Churchill Hospital, Oxford OX3 7LE, UK
| | - Theodore Dos Santos
- Department of Pharmacology, University of Alberta, Edmonton, AB T6G2R3, Canada; Alberta Diabetes Institute, University of Alberta, Edmonton, AB T6G2R3, Canada
| | - Aliya F Spigelman
- Department of Pharmacology, University of Alberta, Edmonton, AB T6G2R3, Canada; Alberta Diabetes Institute, University of Alberta, Edmonton, AB T6G2R3, Canada
| | - Emily M Walker
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48105, USA
| | - Rafael Arrojo E Drigo
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Austin Bautista
- Alberta Diabetes Institute, University of Alberta, Edmonton, AB T6G2R3, Canada
| | - Robert C Jones
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Dana Avrahami
- Endocrinology and Metabolism Department, Hadassah-Hebrew University Medical Centre, Jerusalem, Israel
| | - James Lyon
- Alberta Diabetes Institute, University of Alberta, Edmonton, AB T6G2R3, Canada
| | - Aifang Nie
- Department of Pharmacology, University of Alberta, Edmonton, AB T6G2R3, Canada; Alberta Diabetes Institute, University of Alberta, Edmonton, AB T6G2R3, Canada
| | - Nancy Smith
- Department of Pharmacology, University of Alberta, Edmonton, AB T6G2R3, Canada; Alberta Diabetes Institute, University of Alberta, Edmonton, AB T6G2R3, Canada
| | - Yongneng Zhang
- Department of Medicine, University of Alberta, Edmonton, AB T6G2R3, Canada
| | - Janyne Johnson
- Department of Pharmacology, University of Alberta, Edmonton, AB T6G2R3, Canada; Alberta Diabetes Institute, University of Alberta, Edmonton, AB T6G2R3, Canada
| | - Jocelyn E Manning Fox
- Department of Pharmacology, University of Alberta, Edmonton, AB T6G2R3, Canada; Alberta Diabetes Institute, University of Alberta, Edmonton, AB T6G2R3, Canada
| | | | - Peter E Light
- Department of Pharmacology, University of Alberta, Edmonton, AB T6G2R3, Canada; Alberta Diabetes Institute, University of Alberta, Edmonton, AB T6G2R3, Canada
| | - Klaus H Kaestner
- Department of Genetics and Institute for Diabetes, Obesity and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Seung K Kim
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA; Stanford Diabetes Research Center, Stanford University, Stanford, CA 94305, USA
| | - Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, Churchill Hospital, Oxford OX3 7LE, UK
| | - Roland W Stein
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Stephen R Quake
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA; Chan Zuckerberg Biohub, San Francisco, CA 94518, USA; Department of Applied Physics, Stanford University, Stanford, CA 94305, USA
| | - Patrick E MacDonald
- Department of Pharmacology, University of Alberta, Edmonton, AB T6G2R3, Canada; Alberta Diabetes Institute, University of Alberta, Edmonton, AB T6G2R3, Canada.
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27
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Mourad NI, Xhema D, Gianello P. In vitro assessment of pancreatic hormone secretion from isolated porcine islets. Front Endocrinol (Lausanne) 2022; 13:935060. [PMID: 36034433 PMCID: PMC9402940 DOI: 10.3389/fendo.2022.935060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 07/25/2022] [Indexed: 11/26/2022] Open
Abstract
The potential use of porcine islets for transplantation in humans has triggered interest in understanding porcine islet physiology. However, the number of studies dedicated to this topic has remained limited, as most islet physiologists prefer to use the less time-consuming rodent model or the more clinically relevant human islet. An often-overlooked aspect of pig islet physiology is its alpha cell activity and regulation of its glucagon secretion. In vitro islet perifusion is a reliable method to study the dynamics of hormone secretion in response to different stimuli. We thus used this method to quantify and study glucagon secretion from pig islets. Pancreatic islets were isolated from 20 neonatal (14 to 21-day old) and 5 adult (>2 years) pigs and cultured in appropriate media. Islet perifusion experiments were performed 8 to 10 days post-isolation for neonatal islets and 1 to 2 days post-isolation for adult islets. Insulin and glucagon were quantified in perifusion effluent fractions as well as in islet extracts by RIA. Increasing glucose concentration from 1 mM to 15 mM markedly inhibited glucagon secretion independently of animal age. Interestingly, the effect of high glucose was more drastic on glucagon secretion compared to its effect on insulin secretion. In vivo, glucose injection during IVGTT initiated a quick (2-10 minutes) 3-fold decrease of plasmatic glucagon whereas the increase of plasmatic insulin took 20 minutes to become significant. These results suggest that regulation of glucagon secretion significantly contributes to glucose homeostasis in pigs and might compensate for the mild changes in insulin secretion in response to changes in glucose concentration.
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28
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Hughson BN. The Glucagon-Like Adipokinetic Hormone in Drosophila melanogaster - Biosynthesis and Secretion. Front Physiol 2021; 12:710652. [PMID: 35002748 PMCID: PMC8733639 DOI: 10.3389/fphys.2021.710652] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 09/16/2021] [Indexed: 11/13/2022] Open
Abstract
Metabolic homeostasis requires the precise regulation of circulating sugar titers. In mammals, homeostatic control of circulating sugar titers requires the coordinated secretion and systemic activities of glucagon and insulin. Metabolic homeostasis is similarly regulated in Drosophila melanogaster through the glucagon-like adipokinetic hormone (AKH) and the Drosophila insulin-like peptides (DILPs). In flies and mammals, glucagon and AKH are biosynthesized in and secreted from specialized endocrine cells. KATP channels borne on these cells respond to fluctuations in circulating glucose titers and thereby regulate glucagon secretion. The influence of glucagon in the pathogenesis of type 2 diabetes mellitus is now recognized, and a crucial mechanism that regulates glucagon secretion was reported nearly a decade ago. Ongoing efforts to develop D. melanogaster models for metabolic syndrome must build upon this seminal work. These efforts make a critical review of AKH physiology timely. This review focuses on AKH biosynthesis and the regulation of glucose-responsive AKH secretion through changes in CC cell electrical activity. Future directions for AKH research in flies are discussed, including the development of models for hyperglucagonemia and epigenetic inheritance of acquired metabolic traits. Many avenues of AKH physiology remain to be explored and thus present great potential for improving the utility of D. melanogaster in metabolic research.
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Affiliation(s)
- Bryon N. Hughson
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada
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29
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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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Toki S, Newcomb DC, Printz RL, Cahill KN, Boyd KL, Niswender KD, Peebles RS. Glucagon-like peptide-1 receptor agonist inhibits aeroallergen-induced activation of ILC2 and neutrophilic airway inflammation in obese mice. Allergy 2021; 76:3433-3445. [PMID: 33955007 PMCID: PMC8597133 DOI: 10.1111/all.14879] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Revised: 03/31/2021] [Accepted: 04/10/2021] [Indexed: 01/04/2023]
Abstract
BACKGROUND Obesity is a risk factor for the development of asthma. However, pharmacologic therapeutic strategies that specifically target obese asthmatics have not been identified. We hypothesize that glucagon-like peptide-1 receptor agonist (GLP-1RA) treatment inhibits aeroallergen-induced early innate airway inflammation in a mouse model of asthma in the setting of obesity. METHODS SWR (lean) and TALLYHO (obese) mice were challenged intranasally with Alternaria alternata extract (Alt-Ext) or PBS for 4 consecutive days concurrent with GLP-1RA or vehicle treatment. RESULTS TALLYHO mice had greater Alt-Ext-induced airway neutrophilia and lung protein expression of IL-5, IL-13, CCL11, CXCL1, and CXCL5, in addition to ICAM-1 expression on lung epithelial cells compared with SWR mice, and all endpoints were reduced by GLP-1RA treatment. Alt-Ext significantly increased BALF IL-33 in both TALLYHO and SWR mice compared to PBS challenge, but there was no difference in the BALF IL-33 levels between these two strains. However, TALLYHO, but not SWR, mice had significantly higher airway TSLP in BALF following Alt-Ext challenge compared to PBS, and BALF TSLP was significantly greater in TALLYHO mice compared to SWR mice following airway Alt-Ext challenge. GLP-1RA treatment significantly decreased the Alt-Ext-induced TSLP and IL-33 release in TALLYHO mice. While TSLP or ST2 inhibition with a neutralizing antibody decreased airway eosinophils, they did not reduce airway neutrophils in TALLYHO mice. CONCLUSIONS These results suggest that GLP-1RA treatment may be a novel pharmacologic therapeutic strategy for obese persons with asthma by inhibiting aeroallergen-induced neutrophilia, a feature not seen with either TSLP or ST2 inhibition.
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Affiliation(s)
- Shinji Toki
- Division of Allergy, Pulmonary, and Critical Care MedicineVanderbilt University School of MedicineNashvilleTNUSA
| | - Dawn C. Newcomb
- Division of Allergy, Pulmonary, and Critical Care MedicineVanderbilt University School of MedicineNashvilleTNUSA
- Department of Pathology, Microbiology, and ImmunologyVanderbilt University School of MedicineNashvilleTNUSA
| | - Richard L. Printz
- Division of Diabetes, Endocrinology, and MetabolismVanderbilt University School of MedicineNashvilleTNUSA
| | - Katherine N. Cahill
- Division of Allergy, Pulmonary, and Critical Care MedicineVanderbilt University School of MedicineNashvilleTNUSA
| | - Kelli L. Boyd
- Department of Pathology, Microbiology, and ImmunologyVanderbilt University School of MedicineNashvilleTNUSA
| | - Kevin D. Niswender
- Division of Diabetes, Endocrinology, and MetabolismVanderbilt University School of MedicineNashvilleTNUSA
- Department of Molecular Physiology and BiophysicsVanderbilt University School of MedicineNashvilleTNUSA
- United States Department of Veterans AffairsTennessee Valley Healthcare SystemNashvilleTNUSA
| | - R. Stokes Peebles
- Division of Allergy, Pulmonary, and Critical Care MedicineVanderbilt University School of MedicineNashvilleTNUSA
- Department of Pathology, Microbiology, and ImmunologyVanderbilt University School of MedicineNashvilleTNUSA
- United States Department of Veterans AffairsTennessee Valley Healthcare SystemNashvilleTNUSA
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EPAC2 acts as a negative regulator in Matrigel-driven tubulogenesis of human microvascular endothelial cells. Sci Rep 2021; 11:19453. [PMID: 34593918 PMCID: PMC8484440 DOI: 10.1038/s41598-021-98906-9] [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: 05/18/2021] [Accepted: 09/16/2021] [Indexed: 11/08/2022] Open
Abstract
Angiogenesis is physiologically essential for embryogenesis and development and reinitiated in adult animals during tissue growth and repair. Forming new vessels from the walls of existing vessels occurs as a multistep process coordinated by sprouting, branching, and a new lumenized network formation. However, little is known regarding the molecular mechanisms that form new tubular structures, especially molecules regulating the proper network density of newly formed capillaries. This study conducted microarray analyses in human primary microvascular endothelial cells (HMVECs) plated on Matrigel. The RAPGEF4 gene that encodes exchange proteins directly activated by cAMP 2 (EPAC2) proteins was increased in Matrigel-driven tubulogenesis. Tube formation was suppressed by the overexpression of EPAC2 and enhanced by EPAC2 knockdown in endothelial cells. Endothelial cell morphology was changed to round cell morphology by EPAC2 overexpression, while EPAC2 knockdown showed an elongated cell shape with filopodia-like protrusions. Furthermore, increased EPAC2 inhibited endothelial cell migration, and ablation of EPAC2 inversely enhanced cell mobility. These results suggest that EPAC2 affects the morphology and migration of microvascular endothelial cells and is involved in the termination and proper network formation of vascular tubes.
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32
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Zhang Y, Han C, Zhu W, Yang G, Peng X, Mehta S, Zhang J, Chen L, Liu Y. Glucagon Potentiates Insulin Secretion Via β-Cell GCGR at Physiological Concentrations of Glucose. Cells 2021; 10:cells10092495. [PMID: 34572144 PMCID: PMC8471175 DOI: 10.3390/cells10092495] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 09/14/2021] [Accepted: 09/15/2021] [Indexed: 12/21/2022] Open
Abstract
Incretin-potentiated glucose-stimulated insulin secretion (GSIS) is critical to maintaining euglycemia, of which GLP-1 receptor (GLP-1R) on β-cells plays an indispensable role. Recently, α-cell-derived glucagon but not intestine-derived GLP-1 has been proposed as the critical hormone that potentiates GSIS via GLP-1R. However, the function of glucagon receptors (GCGR) on β-cells remains elusive. Here, using GCGR or GLP-1R antagonists, in combination with glucagon, to treat single β-cells, α-β cell clusters and isolated islets, we found that glucagon potentiates insulin secretion via β-cell GCGR at physiological but not high concentrations of glucose. Furthermore, we transfected primary mouse β-cells with RAB-ICUE (a genetically encoded cAMP fluorescence indicator) to monitor cAMP level after glucose stimulation and GCGR activation. Using specific inhibitors of different adenylyl cyclase (AC) family members, we revealed that high glucose concentration or GCGR activation independently evoked cAMP elevation via AC5 in β-cells, thus high glucose stimulation bypassed GCGR in promoting insulin secretion. Additionally, we generated β-cell-specific GCGR knockout mice which glucose intolerance was more severe when fed a high-fat diet (HFD). We further found that β-cell GCGR activation promoted GSIS more than GLP-1R in HFD, indicating the critical role of GCGR in maintaining glucose homeostasis during nutrient overload.
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Affiliation(s)
- Yulin Zhang
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China; (Y.Z.); (C.H.); (W.Z.); (G.Y.); (X.P.)
| | - Chengsheng Han
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China; (Y.Z.); (C.H.); (W.Z.); (G.Y.); (X.P.)
| | - Wenzhen Zhu
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China; (Y.Z.); (C.H.); (W.Z.); (G.Y.); (X.P.)
| | - Guoyi Yang
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China; (Y.Z.); (C.H.); (W.Z.); (G.Y.); (X.P.)
| | - Xiaohong Peng
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China; (Y.Z.); (C.H.); (W.Z.); (G.Y.); (X.P.)
| | - Sohum Mehta
- Department of Pharmacology, University of California San Diego, La Jolla, CA 92093-0702, USA; (S.M.); (J.Z.)
| | - Jin Zhang
- Department of Pharmacology, University of California San Diego, La Jolla, CA 92093-0702, USA; (S.M.); (J.Z.)
| | - Liangyi Chen
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, College of Future Technology, Peking University, Beijing 100871, China; (Y.Z.); (C.H.); (W.Z.); (G.Y.); (X.P.)
- PKU-IDG/McGovern Institute for Brain Research, Beijing 100871, China
- Beijing Academy of Artificial Intelligence, Beijing 100871, China
- Correspondence: (L.C.); (Y.L.)
| | - Yanmei Liu
- Key Laboratory of Brain, Cognition and Education Sciences, Ministry of Education, Institute for Brain Research and Rehabilitation, South China Normal University, Guangzhou 510631, China
- Correspondence: (L.C.); (Y.L.)
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Wang Y, Liu Q, Kang SG, Huang K, Tong T. Dietary Bioactive Ingredients Modulating the cAMP Signaling in Diabetes Treatment. Nutrients 2021; 13:nu13093038. [PMID: 34578916 PMCID: PMC8467569 DOI: 10.3390/nu13093038] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Revised: 08/25/2021] [Accepted: 08/27/2021] [Indexed: 02/06/2023] Open
Abstract
As the prevalence of diabetes increases progressively, research to develop new therapeutic approaches and the search for more bioactive compounds are attracting more attention. Over the past decades, studies have suggested that cyclic adenosine monophosphate (cAMP), the important intracellular second messenger, is a key regulator of metabolism and glucose homeostasis in diverse physiopathological states in multiple organs including the pancreas, liver, gut, skeletal muscle, adipose tissues, brain, and kidney. The multiple characteristics of dietary compounds and their favorable influence on diabetes pathogenesis, as well as their intersections with the cAMP signaling pathway, indicate that these compounds have a beneficial effect on the regulation of glucose homeostasis. In this review, we outline the current understanding of the diverse functions of cAMP in different organs involved in glucose homeostasis and show that a diversity of bioactive ingredients from foods activate or inhibit cAMP signaling, resulting in the improvement of the diabetic pathophysiological process. It aims to highlight the diabetes-preventative or -therapeutic potential of dietary bioactive ingredients targeting cAMP signaling.
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Affiliation(s)
- Yanan Wang
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China;
| | - Qing Liu
- Jilin Green Food Engineering Research Institute, Changchun 130022, China;
| | - Seong-Gook Kang
- Department of Food Engineering, Mokpo National University, Muangun 58554, Korea;
| | - Kunlun Huang
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China;
- Key Laboratory of Safety Assessment of Genetically Modified Organism (Food Safety), Ministry of Agriculture, Beijing 100083, China
- Correspondence: (K.H.); (T.T.)
| | - Tao Tong
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China;
- Correspondence: (K.H.); (T.T.)
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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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Ng XW, Chung YH, Piston DW. Intercellular Communication in the Islet of Langerhans in Health and Disease. Compr Physiol 2021; 11:2191-2225. [PMID: 34190340 PMCID: PMC8985231 DOI: 10.1002/cphy.c200026] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Blood glucose homeostasis requires proper function of pancreatic islets, which secrete insulin, glucagon, and somatostatin from the β-, α-, and δ-cells, respectively. Each islet cell type is equipped with intrinsic mechanisms for glucose sensing and secretory actions, but these intrinsic mechanisms alone cannot explain the observed secretory profiles from intact islets. Regulation of secretion involves interconnected mechanisms among and between islet cell types. Islet cells lose their normal functional signatures and secretory behaviors upon dispersal as compared to intact islets and in vivo. In dispersed islet cells, the glucose response of insulin secretion is attenuated from that seen from whole islets, coordinated oscillations in membrane potential and intracellular Ca2+ activity, as well as the two-phase insulin secretion profile, are missing, and glucagon secretion displays higher basal secretion profile and a reverse glucose-dependent response from that of intact islets. These observations highlight the critical roles of intercellular communication within the pancreatic islet, and how these communication pathways are crucial for proper hormonal and nonhormonal secretion and glucose homeostasis. Further, misregulated secretions of islet secretory products that arise from defective intercellular islet communication are implicated in diabetes. Intercellular communication within the islet environment comprises multiple mechanisms, including electrical synapses from gap junctional coupling, paracrine interactions among neighboring cells, and direct cell-to-cell contacts in the form of juxtacrine signaling. In this article, we describe the various mechanisms that contribute to proper islet function for each islet cell type and how intercellular islet communications are coordinated among the same and different islet cell types. © 2021 American Physiological Society. Compr Physiol 11:2191-2225, 2021.
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Affiliation(s)
- Xue W Ng
- Department of Cell Biology and Physiology, Washington University, St Louis, Missouri, USA
| | - Yong H Chung
- Department of Cell Biology and Physiology, Washington University, St Louis, Missouri, USA
| | - David W Piston
- Department of Cell Biology and Physiology, Washington University, St Louis, Missouri, USA
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36
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Cross-Talk Between the Adenylyl Cyclase/cAMP Pathway and Ca 2+ Homeostasis. Rev Physiol Biochem Pharmacol 2021; 179:73-116. [PMID: 33398503 DOI: 10.1007/112_2020_55] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Cyclic AMP and Ca2+ are the first second or intracellular messengers identified, unveiling the cellular mechanisms activated by a plethora of extracellular signals, including hormones. Cyclic AMP generation is catalyzed by adenylyl cyclases (ACs), which convert ATP into cAMP and pyrophosphate. By the way, Ca2+, as energy, can neither be created nor be destroyed; Ca2+ can only be transported, from one compartment to another, or chelated by a variety of Ca2+-binding molecules. The fine regulation of cytosolic concentrations of cAMP and free Ca2+ is crucial in cell function and there is an intimate cross-talk between both messengers to fine-tune the cellular responses. Cancer is a multifactorial disease resulting from a combination of genetic and environmental factors. Frequent cases of cAMP and/or Ca2+ homeostasis remodeling have been described in cancer cells. In those tumoral cells, cAMP and Ca2+ signaling plays a crucial role in the development of hallmarks of cancer, including enhanced proliferation and migration, invasion, apoptosis resistance, or angiogenesis. This review summarizes the cross-talk between the ACs/cAMP and Ca2+ intracellular pathways with special attention to the functional and reciprocal regulation between Orai1 and AC8 in normal and cancer cells.
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37
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Lafferty RA, O’Harte FPM, Irwin N, Gault VA, Flatt PR. Proglucagon-Derived Peptides as Therapeutics. Front Endocrinol (Lausanne) 2021; 12:689678. [PMID: 34093449 PMCID: PMC8171296 DOI: 10.3389/fendo.2021.689678] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 05/05/2021] [Indexed: 12/12/2022] Open
Abstract
Initially discovered as an impurity in insulin preparations, our understanding of the hyperglycaemic hormone glucagon has evolved markedly over subsequent decades. With description of the precursor proglucagon, we now appreciate that glucagon was just the first proglucagon-derived peptide (PGDP) to be characterised. Other bioactive members of the PGDP family include glucagon-like peptides -1 and -2 (GLP-1 and GLP-2), oxyntomodulin (OXM), glicentin and glicentin-related pancreatic peptide (GRPP), with these being produced via tissue-specific processing of proglucagon by the prohormone convertase (PC) enzymes, PC1/3 and PC2. PGDP peptides exert unique physiological effects that influence metabolism and energy regulation, which has witnessed several of them exploited in the form of long-acting, enzymatically resistant analogues for treatment of various pathologies. As such, intramuscular glucagon is well established in rescue of hypoglycaemia, while GLP-2 analogues are indicated in the management of short bowel syndrome. Furthermore, since approval of the first GLP-1 mimetic for the management of Type 2 diabetes mellitus (T2DM) in 2005, GLP-1 therapeutics have become a mainstay of T2DM management due to multifaceted and sustainable improvements in glycaemia, appetite control and weight loss. More recently, longer-acting PGDP therapeutics have been developed, while newfound benefits on cardioprotection, bone health, renal and liver function and cognition have been uncovered. In the present article, we discuss the physiology of PGDP peptides and their therapeutic applications, with a focus on successful design of analogues including dual and triple PGDP receptor agonists currently in clinical development.
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Affiliation(s)
| | | | | | - Victor A. Gault
- School of Biomedical Sciences, Ulster University, Coleraine, United Kingdom
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38
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Ghazvini Zadeh EH, Huang Z, Xia J, Li D, Davidson HW, Li WH. ZIGIR, a Granule-Specific Zn 2+ Indicator, Reveals Human Islet α Cell Heterogeneity. Cell Rep 2021; 32:107904. [PMID: 32668245 DOI: 10.1016/j.celrep.2020.107904] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 05/04/2020] [Accepted: 06/23/2020] [Indexed: 02/07/2023] Open
Abstract
Numerous mammalian cells contain abundant Zn2+ in their secretory granules, yet available Zn2+ sensors lack the desired specificity and sensitivity for imaging granular Zn2+. We developed a fluorescent zinc granule indicator, ZIGIR, that possesses numerous desired properties for live cell imaging, including >100-fold fluorescence enhancement, membrane permeability, and selective enrichment to acidic granules. The combined advantages endow ZIGIR with superior sensitivity and specificity for imaging granular Zn2+. ZIGIR enables separation of heterogenous β cells based on their insulin content and sorting of mouse islets into pure α cells and β cells. In human islets, ZIGIR facilitates sorting of endocrine cells into highly enriched α cells and β cells, reveals unexpectedly high Zn2+ activity in the somatostatin granule of some δ cells, and uncovers variation in the glucagon content among human α cells. We expect broad applications of ZIGIR for studying Zn2+ biology and Zn2+-rich secretory granules and for engineering β cells with high insulin content for treating diabetes.
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Affiliation(s)
- Ebrahim H Ghazvini Zadeh
- Departments of Cell Biology and Biochemistry, University of Texas Southwestern Medical Center, 6000 Harry Hines Blvd., Dallas, TX 75390-9039, USA
| | - ZhiJiang Huang
- Departments of Cell Biology and Biochemistry, University of Texas Southwestern Medical Center, 6000 Harry Hines Blvd., Dallas, TX 75390-9039, USA
| | - Jing Xia
- Departments of Cell Biology and Biochemistry, University of Texas Southwestern Medical Center, 6000 Harry Hines Blvd., Dallas, TX 75390-9039, USA; Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX, USA
| | - Daliang Li
- Departments of Cell Biology and Biochemistry, University of Texas Southwestern Medical Center, 6000 Harry Hines Blvd., Dallas, TX 75390-9039, USA
| | - Howard W Davidson
- Barbara Davis Center for Diabetes, University of Colorado Denver Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Wen-Hong Li
- Departments of Cell Biology and Biochemistry, University of Texas Southwestern Medical Center, 6000 Harry Hines Blvd., Dallas, TX 75390-9039, USA.
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Wang X, Kang J, Liu Q, Tong T, Quan H. Fighting Diabetes Mellitus: Pharmacological and Non-pharmacological Approaches. Curr Pharm Des 2021; 26:4992-5001. [PMID: 32723251 DOI: 10.2174/1381612826666200728144200] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 06/29/2020] [Indexed: 02/08/2023]
Abstract
BACKGROUND The increasing worldwide prevalence of diabetes mellitus confers heavy public health issues and points to a large medical need for effective and novel anti-diabetic approaches with negligible adverse effects. Developing effective and novel anti-diabetic approaches to curb diabetes is one of the most foremost scientific challenges. OBJECTIVES This article aims to provide an overview of current pharmacological and non-pharmacological approaches available for the management of diabetes mellitus. METHODS Research articles that focused on pharmacological and non-pharmacological interventions for diabetes were collected from various search engines such as Science Direct and Scopus, using keywords like diabetes, glucagon-like peptide-1, glucose homeostasis, etc. Results: We review in detail several key pathways and pharmacological targets (e.g., the G protein-coupled receptors- cyclic adenosine monophosphate, 5'-adenosine monophosphate-activated protein kinase, sodium-glucose cotransporters 2, and peroxisome proliferator activated-receptor gamma signaling pathways) that are vital in the regulation of glucose homeostasis. The currently approved diabetes medications, the pharmacological potentials of naturally occurring compounds as promising interventions for diabetes, and the non-pharmacological methods designed to mitigate diabetes are summarized and discussed. CONCLUSION Pharmacological-based approaches such as insulin, metformin, sodium-glucose cotransporters 2 inhibitor, sulfonylureas, glucagon-like peptide-1 receptor agonists, and dipeptidyl peptidase IV inhibitors represent the most important strategies in diabetes management. These approved diabetes medications work via targeting the central signaling pathways related to the etiology of diabetes. Non-pharmacological approaches, including dietary modification, increased physical activity, and microbiota-based therapy are the other cornerstones for diabetes treatment. Pharmacological-based approaches may be incorporated when lifestyle modification alone is insufficient to achieve positive outcomes.
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Affiliation(s)
- Xin Wang
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Jinhong Kang
- College of Pharmacy, Korea University, Sejong 30019, Korea
| | - Qing Liu
- Jilin Green Food Engineering Research Institute, Changchun, 130022, China
| | - Tao Tong
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Helong Quan
- Exercise and Metabolism Research Center, College of Physical Education and Health Sciences, Zhejiang Normal University, Jinhua, Zhejiang Province, 321004, China
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40
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Tanday N, Flatt PR, Irwin N. Metabolic responses and benefits of glucagon-like peptide-1 (GLP-1) receptor ligands. Br J Pharmacol 2021; 179:526-541. [PMID: 33822370 PMCID: PMC8820187 DOI: 10.1111/bph.15485] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 03/19/2021] [Accepted: 03/30/2021] [Indexed: 12/19/2022] Open
Abstract
Glucagon-like peptide-1 (GLP-1) is an incretin hormone that has undergone a revolutionary turnaround from discovery to clinically approved therapeutic. Rapid progress in drug design and formulation has led from initial development of short- and long-acting drugs suitable for daily or weekly parenteral administration, respectively, through to the most recent approval of an orally active GLP-1 agent. The current review outlines the biological action profile of GLP-1 including the various beneficial metabolic responses in pancreatic and extra-pancreatic tissues, including the gastrointestinal tract, liver, bone and kidney as well as the reproductive cardiovascular and CNS. We then briefly consider clinically approved GLP-1 receptor ligands and recent advances in this field. Given the sustained evolution in the area of GLP-1 drug development and excellent safety profile, as well as the plethora of metabolic benefits, clinical approval for use in diseases beyond diabetes and obesity is very much conceivable.
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Affiliation(s)
- Neil Tanday
- Diabetes Research Group, Ulster University, Coleraine, UK
| | - Peter R Flatt
- Diabetes Research Group, Ulster University, Coleraine, UK
| | - Nigel Irwin
- Diabetes Research Group, Ulster University, Coleraine, UK
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41
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McLean BA, Wong CK, Campbell JE, Hodson DJ, Trapp S, Drucker DJ. Revisiting the Complexity of GLP-1 Action from Sites of Synthesis to Receptor Activation. Endocr Rev 2021; 42:101-132. [PMID: 33320179 PMCID: PMC7958144 DOI: 10.1210/endrev/bnaa032] [Citation(s) in RCA: 112] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Indexed: 02/06/2023]
Abstract
Glucagon-like peptide-1 (GLP-1) is produced in gut endocrine cells and in the brain, and acts through hormonal and neural pathways to regulate islet function, satiety, and gut motility, supporting development of GLP-1 receptor (GLP-1R) agonists for the treatment of diabetes and obesity. Classic notions of GLP-1 acting as a meal-stimulated hormone from the distal gut are challenged by data supporting production of GLP-1 in the endocrine pancreas, and by the importance of brain-derived GLP-1 in the control of neural activity. Moreover, attribution of direct vs indirect actions of GLP-1 is difficult, as many tissue and cellular targets of GLP-1 action do not exhibit robust or detectable GLP-1R expression. Furthermore, reliable detection of the GLP-1R is technically challenging, highly method dependent, and subject to misinterpretation. Here we revisit the actions of GLP-1, scrutinizing key concepts supporting gut vs extra-intestinal GLP-1 synthesis and secretion. We discuss new insights refining cellular localization of GLP-1R expression and integrate recent data to refine our understanding of how and where GLP-1 acts to control inflammation, cardiovascular function, islet hormone secretion, gastric emptying, appetite, and body weight. These findings update our knowledge of cell types and mechanisms linking endogenous vs pharmacological GLP-1 action to activation of the canonical GLP-1R, and the control of metabolic activity in multiple organs.
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Affiliation(s)
- Brent A McLean
- Department of Medicine, Lunenfeld-Tanenbaum Research Institute, Mt. Sinai Hospital, University of Toronto, Ontario, Canada
| | - Chi Kin Wong
- Department of Medicine, Lunenfeld-Tanenbaum Research Institute, Mt. Sinai Hospital, University of Toronto, Ontario, Canada
| | - Jonathan E Campbell
- The Department of Medicine, Division of Endocrinology, Department of Pharmacology and Cancer Biology, Duke Molecular Physiology Institute, Duke University, Durham, NC, USA
| | - David J Hodson
- Institute of Metabolism and Systems Research (IMSR), University of Birmingham, and Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, UK
| | - Stefan Trapp
- Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology & Pharmacology, UCL, London, UK
| | - Daniel J Drucker
- Department of Medicine, Lunenfeld-Tanenbaum Research Institute, Mt. Sinai Hospital, University of Toronto, Ontario, Canada
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Viloria K, Hewison M, Hodson DJ. Vitamin D binding protein/GC-globulin: a novel regulator of alpha cell function and glucagon secretion. J Physiol 2021; 600:1119-1133. [PMID: 33719063 DOI: 10.1113/jp280890] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 03/05/2021] [Indexed: 12/24/2022] Open
Abstract
The contribution of glucagon to type 1 and type 2 diabetes has long been known, but the underlying defects in alpha cell function are not well-described. During both disease states, alpha cells respond inappropriately to stimuli, leading to dysregulated glucagon secretion, impaired glucose tolerance and hypoglycaemia. The mechanisms involved in this dysfunction are complex, but possibly include changes in alpha cell glucose-sensing, alpha cell de-differentiation, paracrine feedback, as well as alpha cell mass. However, the molecular underpinnings of alpha cell failure are still poorly understood. Recent transcriptomic analyses have identified vitamin D binding protein (DBP), encoded by GC/Gc, as an alpha cell signature gene. DBP is highly localized to the liver and alpha cells and is virtually absent from other tissues and cell types under non-pathological conditions. While the vitamin D transportation role of DBP is well characterized in the liver and circulation, its function in alpha cells remains more enigmatic. Recent work reveals that loss of DBP leads to smaller and hyperplastic alpha cells, which secrete less glucagon in response to low glucose concentration, despite vitamin D sufficiency. Alpha cells lacking DBP display impaired Ca2+ fluxes and Na+ conductance, as well as changes in glucagon granule distribution. Underlying these defects is an increase in the ratio of cytoskeletal F-actin to G-actin, highlighting a novel intracellular actin scavenging role for DBP in islets.
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Affiliation(s)
- Katrina Viloria
- Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Birmingham, B15 2TT, UK.,Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, B15 2TT, UK.,Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, UK
| | - Martin Hewison
- Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Birmingham, B15 2TT, UK.,Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, B15 2TT, UK
| | - David J Hodson
- Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Birmingham, B15 2TT, UK.,Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, B15 2TT, UK.,Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, UK
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43
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Croze ML, Flisher MF, Guillaume A, Tremblay C, Noguchi GM, Granziera S, Vivot K, Castillo VC, Campbell SA, Ghislain J, Huising MO, Poitout V. Free fatty acid receptor 4 inhibitory signaling in delta cells regulates islet hormone secretion in mice. Mol Metab 2021; 45:101166. [PMID: 33484949 PMCID: PMC7873385 DOI: 10.1016/j.molmet.2021.101166] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 01/08/2021] [Accepted: 01/11/2021] [Indexed: 02/06/2023] Open
Abstract
OBJECTIVE Maintenance of glucose homeostasis requires the precise regulation of hormone secretion from the endocrine pancreas. Free fatty acid receptor 4 (FFAR4/GPR120) is a G protein-coupled receptor whose activation in islets of Langerhans promotes insulin and glucagon secretion and inhibits somatostatin secretion. However, the contribution of individual islet cell types (α, β, and δ cells) to the insulinotropic and glucagonotropic effects of GPR120 remains unclear. As gpr120 mRNA is enriched in somatostatin-secreting δ cells, we hypothesized that GPR120 activation stimulates insulin and glucagon secretion via inhibition of somatostatin release. METHODS Glucose tolerance tests were performed in mice after administration of selective GPR120 agonist Compound A. Insulin, glucagon, and somatostatin secretion were measured in static incubations of isolated mouse islets in response to endogenous (ω-3 polyunsaturated fatty acids) and/or pharmacological (Compound A and AZ-13581837) GPR120 agonists. The effect of Compound A on hormone secretion was tested further in islets isolated from mice with global or somatostatin cell-specific knock-out of gpr120. Gpr120 expression was assessed in pancreatic sections by RNA in situ hybridization. Cyclic AMP (cAMP) and calcium dynamics in response to pharmacological GPR120 agonists were measured specifically in α, β, and δ cells in intact islets using cAMPER and GCaMP6 reporter mice, respectively. RESULTS Acute exposure to Compound A increased glucose tolerance, circulating insulin, and glucagon levels in vivo. Endogenous and/or pharmacological GPR120 agonists reduced somatostatin secretion in isolated islets and concomitantly demonstrated dose-dependent potentiation of glucose-stimulated insulin secretion and arginine-stimulated glucagon secretion. Gpr120 was enriched in δ cells. Pharmacological GPR120 agonists reduced cAMP and calcium levels in δ cells but increased these signals in α and β cells. Compound A-mediated inhibition of somatostatin secretion was insensitive to pertussis toxin. The effect of Compound A on hormone secretion was completely absent in islets from mice with either global or somatostatin cell-specific deletion of gpr120 and partially reduced upon blockade of somatostatin receptor signaling by cyclosomatostatin. CONCLUSIONS Inhibitory GPR120 signaling in δ cells contributes to both insulin and glucagon secretion in part by mitigating somatostatin release.
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Affiliation(s)
- Marine L Croze
- Montreal Diabetes Research Center, CRCHUM, Montréal, QC, Canada
| | - Marcus F Flisher
- Department of Neurobiology, Physiology, and Behavior, College of Biological Sciences, University of California Davis, Davis, CA, USA
| | | | | | - Glyn M Noguchi
- Department of Neurobiology, Physiology, and Behavior, College of Biological Sciences, University of California Davis, Davis, CA, USA
| | | | - Kevin Vivot
- Montreal Diabetes Research Center, CRCHUM, Montréal, QC, Canada
| | - Vincent C Castillo
- Department of Neurobiology, Physiology, and Behavior, College of Biological Sciences, University of California Davis, Davis, CA, USA
| | | | - Julien Ghislain
- Montreal Diabetes Research Center, CRCHUM, Montréal, QC, Canada
| | - Mark O Huising
- Department of Neurobiology, Physiology, and Behavior, College of Biological Sciences, University of California Davis, Davis, CA, USA; Department of Physiology and Membrane Biology, School of Medicine, University of California Davis, Davis, CA, USA
| | - Vincent Poitout
- Montreal Diabetes Research Center, CRCHUM, 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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45
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Imaging Meets Cytometry: Analyzing Heterogeneous Functional Microscopic Data from Living Cell Populations. J Imaging 2021; 7:jimaging7010009. [PMID: 34460580 PMCID: PMC8321243 DOI: 10.3390/jimaging7010009] [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: 12/17/2020] [Revised: 01/06/2021] [Accepted: 01/09/2021] [Indexed: 12/27/2022] Open
Abstract
Biological tissue consists of populations of cells exhibiting different responses to pharmacological stimuli. To probe the heterogeneity of cell function, we propose a multiplexed approach based on real‐time imaging of the secondary messenger levels within each cell of the tissue, followed by extraction of the changes of single‐cell fluorescence over time. By utilizing a piecewise baseline correction, we were able to quantify the effects of multiple pharmacological stimuli added and removed sequentially to pancreatic islets of Langerhans, thereby performing a deep functional profiling for each cell within the islet. Cluster analysis based on the functional profile demonstrated dose‐dependent changes in statistical inter‐relationships between islet cell populations. We therefore believe that the functional cytometric approach can be used for routine quantitative profiling of the tissue for drug screening or pathological testing.
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46
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Bédécarrats GY, Hanlon C, Tsutsui K. Gonadotropin Inhibitory Hormone and Its Receptor: Potential Key to the Integration and Coordination of Metabolic Status and Reproduction. Front Endocrinol (Lausanne) 2021; 12:781543. [PMID: 35095760 PMCID: PMC8792613 DOI: 10.3389/fendo.2021.781543] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 12/02/2021] [Indexed: 12/18/2022] Open
Abstract
Since its discovery as a novel gonadotropin inhibitory peptide in 2000, the central and peripheral roles played by gonadotropin-inhibiting hormone (GnIH) have been significantly expanded. This is highlighted by the wide distribution of its receptor (GnIH-R) within the brain and throughout multiple peripheral organs and tissues. Furthermore, as GnIH is part of the wider RF-amide peptides family, many orthologues have been characterized across vertebrate species, and due to the promiscuity between ligands and receptors within this family, confusion over the nomenclature and function has arisen. In this review, we intend to first clarify the nomenclature, prevalence, and distribution of the GnIH-Rs, and by reviewing specific localization and ligand availability, we propose an integrative role for GnIH in the coordination of reproductive and metabolic processes. Specifically, we propose that GnIH participates in the central regulation of feed intake while modulating the impact of thyroid hormones and the stress axis to allow active reproduction to proceed depending on the availability of resources. Furthermore, beyond the central nervous system, we also propose a peripheral role for GnIH in the control of glucose and lipid metabolism at the level of the liver, pancreas, and adipose tissue. Taken together, evidence from the literature strongly suggests that, in fact, the inhibitory effect of GnIH on the reproductive axis is based on the integration of environmental cues and internal metabolic status.
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Affiliation(s)
- Grégoy Y. Bédécarrats
- Department of Animal Biosciences, University of Guelph, Guelph, ON, Canada
- *Correspondence: Grégoy Y. Bédécarrats,
| | - Charlene Hanlon
- Department of Animal Biosciences, University of Guelph, Guelph, ON, Canada
| | - Kazuyoshi Tsutsui
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashihiroshima, Japan
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47
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Drott CJ, Norman D, Espes D. CART decreases islet blood flow, but has no effect on total pancreatic blood flow and glucose tolerance in anesthetized rats. Peptides 2021; 135:170431. [PMID: 33098940 DOI: 10.1016/j.peptides.2020.170431] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 10/12/2020] [Accepted: 10/12/2020] [Indexed: 01/08/2023]
Abstract
Cocaine- and amphetamine-regulated transcript (CART) is a neurotransmitter and hormone, involved in the regulation of e.g. food intake, body weight, reward and addiction, and stress response. CART has also been found to affect insulin secretion and beta cell morphology, both in vivo and in vitro. Furthermore, CART affects regulation of the cardiovascular system and helps to modulate vascular tone. The present study evaluated the local effect of CART on the pancreatic and islet circulation and function. CART (25 μg/h) or saline, combinations of CART and endothelin-A receptor antagonist (BQ123; 100 μg/kg), and glucose (2 g/kg) were intravenously infused in Sprague Dawley rats followed by blood flow measurements using a microsphere technique. Separately, CART-infused animals underwent an intravenous glucose tolerance test (ivGTT). The direct effect of CART on insulin release was investigated using isolated islets from Sprague Dawley rats. CART reduced islet blood flow, without reduction in total pancreatic blood flow. The normal glucose-induced islet blood flow increase was diminished by CART, albeit still present. Simultaneously, CART had no effect on systemic-, intestinal- or renal blood flow. The endothelin-A receptor antagonist BQ123 together with CART had no pancreatic vascular effects. We found that CART has pronounced vascular constrictive actions restricted to the pancreatic islet circulation but had no effect on insulin release neither in vivo nor in vitro. The mechanisms behind the vascular effects are still unknown, but may reflect a direct action on pancreatic blood vessels.
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Affiliation(s)
- Carl Johan Drott
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden.
| | - Daniel Norman
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Daniel Espes
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden; Department of Medical Sciences, Uppsala University, Uppsala, Sweden
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48
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Sarnobat D, Moffett CR, Tanday N, Reimann F, Gribble FM, Flatt PR, Tarasov AI. Antidiabetic drug therapy alleviates type 1 diabetes in mice by promoting pancreatic α-cell transdifferentiation. Biochem Pharmacol 2020; 182:114216. [PMID: 32926875 PMCID: PMC7614179 DOI: 10.1016/j.bcp.2020.114216] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 09/03/2020] [Accepted: 09/04/2020] [Indexed: 12/17/2022]
Abstract
Gut incretins, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP), enhance secretion of insulin in a glucose-dependent manner, predominantly by elevating cytosolic levels of cAMP in pancreatic β-cells. Successful targeting of the incretin pathway by several drugs, however, suggests the antidiabetic mechanism is likely to span beyond the acute effect on hormone secretion and include, for instance, stimulation of β-cell growth and/or proliferation. Likewise, the antidiabetic action of kidney sodium-glucose linked transporter-2 (SGLT-2) inhibitors exceeds simple increase glucose excretion. Potential reasons for these 'added benefits' may lie in the long-term effects of these signals on developmental aspects of pancreatic islet cells. In this work, we explored if the incretin mimetics or SGLT-2 inhibitors can affect the size of the islet α- or β-cell compartments, under the condition of β-cell stress. To that end, we utilised mice expressing YFP specifically in pancreatic α-cells, in which we modelled type 1 diabetes by injecting streptozotocin, followed by a 10-day administration of liraglutide, sitagliptin or dapagliflozin. We observed an onset of diabetic phenotype, which was partially reversed by the administration of the antidiabetic drugs. The mechanism for the reversal included induction of β-cell proliferation, decrease in β-cell apoptosis and, for the incretin mimetics, transdifferentiation of α-cells into β-cells. Our data therefore emphasize the role of chronic incretin signalling in induction of α-/β-cell transdifferentiation. We conclude that incretin peptides may act directly on islet cells, making use of the endogenous local sites of 'ectopic' expression, whereas SGLT-2 inhibitors work via protecting β-cells from chronic hyperglycaemia.
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Affiliation(s)
- Dipak Sarnobat
- School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine, BT52 1SA, UK
| | - Charlotte R Moffett
- School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine, BT52 1SA, UK
| | - Neil Tanday
- School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine, BT52 1SA, UK
| | - Frank Reimann
- Metabolic Research Laboratories, Wellcome Trust–MRC Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge, CB2 0QQ, UK
| | - Fiona M Gribble
- Metabolic Research Laboratories, Wellcome Trust–MRC Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge, CB2 0QQ, UK
| | - Peter R Flatt
- School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine, BT52 1SA, UK
| | - Andrei I Tarasov
- School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine BT52 1SA, UK.
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49
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Saponaro C, Gmyr V, Thévenet J, Moerman E, Delalleau N, Pasquetti G, Coddeville A, Quenon A, Daoudi M, Hubert T, Vantyghem MC, Bousquet C, Martineau Y, Kerr-Conte J, Staels B, Pattou F, Bonner C. The GLP1R Agonist Liraglutide Reduces Hyperglucagonemia Induced by the SGLT2 Inhibitor Dapagliflozin via Somatostatin Release. Cell Rep 2020; 28:1447-1454.e4. [PMID: 31390560 DOI: 10.1016/j.celrep.2019.07.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 08/02/2018] [Accepted: 07/01/2019] [Indexed: 12/20/2022] Open
Abstract
The newest classes of anti-diabetic agents include sodium-glucose cotransporter 2 (SGLT2) inhibitors and glucagon-like peptide 1 receptor (GLP1R) agonists. The SGLT2 inhibitor dapagliflozin reduces glucotoxicity by glycosuria but elevates glucagon secretion. The GLP1R agonist liraglutide inhibits glucagon; therefore, we hypothesize that the cotreatment of dapagliflozin with liraglutide could reduce hyperglucagonemia and hyperglycemia. Here we use five complementary models: human islet cultures, healthy mice, db/db mice, diet-induced obese (DIO) mice, and somatostatin receptor-2 (SSTR2) KO mice. A single administration of liraglutide and dapagliflozin in combination improves glycemia and reduces dapagliflozin-induced glucagon secretion in diabetic mice. Chronic treatment with liraglutide and dapagliflozin produces a sustainable reduction of glycemia compared with each drug alone. Moreover, liraglutide reduces dapagliflozin-induced glucagon secretion by enhancing somatostatin release, as demonstrated by SSTR2 inhibition in human islets and in mice. Collectively, these data provide mechanistic insights into how intra-islet GLP1R activation is critical for the regulation of glucose homeostasis.
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Affiliation(s)
- Chiara Saponaro
- University of Lille, U1190-EGID, 59000 Lille, France; INSERM, U1190, 59000 Lille, France
| | - Valéry Gmyr
- University of Lille, U1190-EGID, 59000 Lille, France; INSERM, U1190, 59000 Lille, France
| | - Julien Thévenet
- University of Lille, U1190-EGID, 59000 Lille, France; INSERM, U1190, 59000 Lille, France
| | - Ericka Moerman
- University of Lille, U1190-EGID, 59000 Lille, France; INSERM, U1190, 59000 Lille, France
| | - Nathalie Delalleau
- University of Lille, U1190-EGID, 59000 Lille, France; INSERM, U1190, 59000 Lille, France
| | - Gianni Pasquetti
- University of Lille, U1190-EGID, 59000 Lille, France; INSERM, U1190, 59000 Lille, France
| | - Anais Coddeville
- University of Lille, U1190-EGID, 59000 Lille, France; INSERM, U1190, 59000 Lille, France
| | - Audrey Quenon
- University of Lille, U1190-EGID, 59000 Lille, France; INSERM, U1190, 59000 Lille, France
| | - Mehdi Daoudi
- University of Lille, U1190-EGID, 59000 Lille, France; INSERM, U1190, 59000 Lille, France
| | - Thomas Hubert
- University of Lille, U1190-EGID, 59000 Lille, France; INSERM, U1190, 59000 Lille, France
| | - Marie-Christine Vantyghem
- University of Lille, U1190-EGID, 59000 Lille, France; INSERM, U1190, 59000 Lille, France; CHU Lille, Clinique Médicale: Endocrinologie Diabétologie Métabolismes, 59000 Lille, France
| | - Corinne Bousquet
- Cancer Research Center of Toulouse (CRCT), INSERM U1037, University Toulouse III Paul Sabatier, Toulouse, France; Equipe Labellisée Ligue Contre le Cancer, Toulouse, France
| | - Yvan Martineau
- Cancer Research Center of Toulouse (CRCT), INSERM U1037, University Toulouse III Paul Sabatier, Toulouse, France; Equipe Labellisée Ligue Contre le Cancer, Toulouse, France
| | - Julie Kerr-Conte
- University of Lille, U1190-EGID, 59000 Lille, France; INSERM, U1190, 59000 Lille, France
| | - Bart Staels
- University of Lille, U1011-EGID, 59000 Lille, France; INSERM, U1011, 59000 Lille, France; CHU Lille, Service Biochimie Automatisée Pathologies des Protéines, 59000 Lille, France; Institut Pasteur de Lille, 59000 Lille, France
| | - François Pattou
- University of Lille, U1190-EGID, 59000 Lille, France; INSERM, U1190, 59000 Lille, France; CHU Lille, Service de Chirurgie Métabolique et Endocrienne, 59000 Lille, France
| | - Caroline Bonner
- University of Lille, U1190-EGID, 59000 Lille, France; INSERM, U1190, 59000 Lille, France; Institut Pasteur de Lille, 59000 Lille, France.
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50
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Zhang Q, Dou H, Rorsman P. 'Resistance is futile?' - paradoxical inhibitory effects of K ATP channel closure in glucagon-secreting α-cells. J Physiol 2020; 598:4765-4780. [PMID: 32716554 PMCID: PMC7689873 DOI: 10.1113/jp279775] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Accepted: 07/24/2020] [Indexed: 12/12/2022] Open
Abstract
By secreting insulin and glucagon, the β- and α-cells of the pancreatic islets play a central role in the regulation of systemic metabolism. Both cells are equipped with ATP-regulated potassium (KATP ) channels that are regulated by the intracellular ATP/ADP ratio. In β-cells, KATP channels are active at low (non-insulin-releasing) glucose concentrations. An increase in glucose leads to KATP channel closure, membrane depolarization and electrical activity that culminates in elevation of [Ca2+ ]i and initiation of exocytosis of the insulin-containing secretory granules. The α-cells are also equipped with KATP channels but they are under strong tonic inhibition at low glucose, explaining why α-cells are electrically active under hypoglycaemic conditions and generate large Na+ - and Ca2+ -dependent action potentials. Closure of residual KATP channel activity leads to membrane depolarization and an increase in action potential firing but this stimulation of electrical activity is associated with inhibition rather than acceleration of glucagon secretion. This paradox arises because membrane depolarization reduces the amplitude of the action potentials by voltage-dependent inactivation of the Na+ channels involved in action potential generation. Exocytosis in α-cells is tightly linked to the opening of voltage-gated P/Q-type Ca2+ channels, the activation of which is steeply voltage-dependent. Accordingly, the inhibitory effect of the reduced action potential amplitude exceeds the stimulatory effect resulting from the increased action potential frequency. These observations highlight a previously unrecognised role of the action potential amplitude as a key regulator of pancreatic islet hormone secretion.
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Affiliation(s)
- Quan Zhang
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Churchill Hospital, Oxford, OX3 7LE, UK
| | - Haiqiang Dou
- Metabolic Physiology Unit, Institute of Neuroscience and Physiology, University of Göteborg, PO Box 430, Göteborg, SE-405 30, Sweden
| | - Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Churchill Hospital, Oxford, OX3 7LE, UK.,Metabolic Physiology Unit, Institute of Neuroscience and Physiology, University of Göteborg, PO Box 430, Göteborg, SE-405 30, Sweden
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