1
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Hill TG, Gao R, Benrick A, Kothegala L, Rorsman N, Santos C, Acreman S, Briant LJ, Dou H, Gandasi NR, Guida C, Haythorne E, Wallace M, Knudsen JG, Miranda C, Tolö J, Clark A, Davison L, Størling J, Tarasov A, Ashcroft FM, Rorsman P, Zhang Q. Loss of electrical β-cell to δ-cell coupling underlies impaired hypoglycaemia-induced glucagon secretion in type-1 diabetes. Nat Metab 2024:10.1038/s42255-024-01139-z. [PMID: 39313541 DOI: 10.1038/s42255-024-01139-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 08/30/2024] [Indexed: 09/25/2024]
Abstract
Diabetes mellitus involves both insufficient insulin secretion and dysregulation of glucagon secretion1. In healthy people, a fall in plasma glucose stimulates glucagon release and thereby increases counter-regulatory hepatic glucose production. This response is absent in many patients with type-1 diabetes (T1D)2, which predisposes to severe hypoglycaemia that may be fatal and accounts for up to 10% of the mortality in patients with T1D3. In rats with chemically induced or autoimmune diabetes, counter-regulatory glucagon secretion can be restored by SSTR antagonists4-7 but both the underlying cellular mechanism and whether it can be extended to humans remain unestablished. Here, we show that glucagon secretion is not stimulated by low glucose in isolated human islets from donors with T1D, a defect recapitulated in non-obese diabetic mice with T1D. This occurs because of hypersecretion of somatostatin, leading to aberrant paracrine inhibition of glucagon secretion. Normally, KATP channel-dependent hyperpolarization of β-cells at low glucose extends into the δ-cells through gap junctions, culminating in suppression of action potential firing and inhibition of somatostatin secretion. This 'electric brake' is lost following autoimmune destruction of the β-cells, resulting in impaired counter-regulation. This scenario accounts for the clinical observation that residual β-cell function correlates with reduced hypoglycaemia risk8.
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Affiliation(s)
- Thomas G Hill
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, UK
| | - Rui Gao
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, UK
| | - Anna Benrick
- Metabolic Research Unit, Institute of Neuroscience and Physiology, University of Göteborg, Göteborg, Sweden
| | - Lakshmi Kothegala
- Metabolic Research Unit, Institute of Neuroscience and Physiology, University of Göteborg, Göteborg, Sweden
- Department of Developmental Biology and Genetics (DBG), Indian Institute of Science (IISc), Bengaluru, India
| | - Nils Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, UK
| | - Cristiano Santos
- Metabolic Research Unit, Institute of Neuroscience and Physiology, University of Göteborg, Göteborg, Sweden
| | - Samuel Acreman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, UK
- Metabolic Research Unit, Institute of Neuroscience and Physiology, University of Göteborg, Göteborg, Sweden
| | - Linford J Briant
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, UK
| | - Haiqiang Dou
- Metabolic Research Unit, Institute of Neuroscience and Physiology, University of Göteborg, Göteborg, Sweden
| | - Nikhil R Gandasi
- Metabolic Research Unit, Institute of Neuroscience and Physiology, University of Göteborg, Göteborg, Sweden
- Department of Developmental Biology and Genetics (DBG), Indian Institute of Science (IISc), Bengaluru, India
| | - Claudia Guida
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, UK
| | - Elizabeth Haythorne
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Marsha Wallace
- Nuffield Department of Clinical Medicine, University of Oxford, Roosevelt Drive, Oxford, UK
- The Royal Veterinary College, Hatfield, Hertfordshire, UK
| | - Jakob G Knudsen
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, UK
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Caroline Miranda
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, UK
- Metabolic Research Unit, Institute of Neuroscience and Physiology, University of Göteborg, Göteborg, Sweden
| | - Johan Tolö
- Metabolic Research Unit, Institute of Neuroscience and Physiology, University of Göteborg, Göteborg, Sweden
| | - Anne Clark
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, UK
| | - Lucy Davison
- Nuffield Department of Clinical Medicine, University of Oxford, Roosevelt Drive, Oxford, UK
- The Royal Veterinary College, Hatfield, Hertfordshire, UK
| | - Joachim Størling
- Steno Diabetes Center Copenhagen, Translational Type 1 Diabetes Research, Herlev, Denmark
| | - Andrei Tarasov
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, UK
- Biomedical Sciences Research Institute, School of Biomedical Sciences, Ulster University, Coleraine, Northern Ireland, UK
| | - Frances M Ashcroft
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, UK.
- Metabolic Research Unit, Institute of Neuroscience and Physiology, University of Göteborg, Göteborg, Sweden.
- Biomedical Sciences Research Institute, School of Biomedical Sciences, Ulster University, Coleraine, Northern Ireland, UK.
- Oxford National Institute for Health Research, Biomedical Research Centre, Churchill Hospital, Oxford, UK.
| | - Quan Zhang
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, UK.
- Center for Neuroscience and Cell Biology (CNC), Centre for Innovative Biomedicine and Biotechnology (CIBB), University of Coimbra, Coimbra, Portugal.
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2
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Sridhar A, Khan D, Babu G, Irwin N, Gault VA, Flatt PR, Moffett CR. Chronic exposure to incretin metabolites GLP-1(9-36) and GIP(3-42) affect islet morphology and beta cell health in high fat fed mice. Peptides 2024; 178:171254. [PMID: 38815655 DOI: 10.1016/j.peptides.2024.171254] [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: 02/19/2024] [Revised: 04/24/2024] [Accepted: 05/27/2024] [Indexed: 06/01/2024]
Abstract
The incretin hormones, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), are rapidly degraded by dipeptidyl peptidase-4 (DPP-4) to their major circulating metabolites GLP-1(9-36) and GIP(3-42). This study investigates the possible effects of these metabolites, and the equivalent exendin molecule Ex(9-39), on pancreatic islet morphology and constituent alpha and beta cells in high-fat diet (HFD) fed mice. Male Swiss TO-mice (6-8 weeks-old) were maintained on a HFD or normal diet (ND) for 4 months and then received twice-daily subcutaneous injections of GLP-1(9-36), GIP(3-42), Ex(9-39) (25 nmol/kg bw) or saline vehicle (0.9% (w/v) NaCl) over a 60-day period. Metabolic parameters were monitored and excised pancreatic tissues were used for immunohistochemical analysis. Body weight and assessed metabolic indices were not changed by peptide administration. GLP-1(9-36) significantly (p<0.001) increased islet density per mm2 tissue, that was decreased (p<0.05) by HFD. Islet, beta and alpha cell areas were increased (p<0.01) following HFD and subsequently reduced (p<0.01-p<0.001) by GIP(3-42) and Ex(9-39) treatment. While GLP-1(9-36) did not affect islet and beta cell areas in HFD mice, it significantly (p<0.01) decreased alpha cell area. Compared to ND and HFD mice, GIP(3-42) treatment significantly (p<0.05) increased beta cell proliferation. Whilst HFD increased (p<0.001) beta cell apoptosis, this was reduced (p<0.01-p<0.001) by both GLP-1(9-36) and GIP(3-42). These data indicate that the major circulating forms of GLP-1 and GIP, namely GLP-1(9-36) and GIP(3-42) previously considered largely inactive, may directly impact pancreatic morphology, with an important protective effect on beta cell health under conditions of beta cell stress.
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Affiliation(s)
- Ananyaa Sridhar
- Biomedical Sciences Research Institute, Diabetes Research Centre, School of Biomedical Sciences, Ulster University, Coleraine, Northern Ireland, UK.
| | - Dawood Khan
- Biomedical Sciences Research Institute, Diabetes Research Centre, School of Biomedical Sciences, Ulster University, Coleraine, Northern Ireland, UK
| | - Gayathri Babu
- Biomedical Sciences Research Institute, Diabetes Research Centre, School of Biomedical Sciences, Ulster University, Coleraine, Northern Ireland, UK
| | - Nigel Irwin
- Biomedical Sciences Research Institute, Diabetes Research Centre, School of Biomedical Sciences, Ulster University, Coleraine, Northern Ireland, UK
| | - Victor A Gault
- Biomedical Sciences Research Institute, Diabetes Research Centre, School of Biomedical Sciences, Ulster University, Coleraine, Northern Ireland, UK
| | - Peter R Flatt
- Biomedical Sciences Research Institute, Diabetes Research Centre, School of Biomedical Sciences, Ulster University, Coleraine, Northern Ireland, UK
| | - Charlotte R Moffett
- Biomedical Sciences Research Institute, Diabetes Research Centre, School of Biomedical Sciences, Ulster University, Coleraine, Northern Ireland, UK
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Tonet NS, da Silva Marçal DF, da Silva FN, Brunetta HS, Mori MADS, Dos Santos GJ, Moreira ELG, Rafacho A. Moderate chronic sleep perturbation impairs glucose and lipid homeostasis in rats. Sleep 2024; 47:zsae118. [PMID: 38788154 DOI: 10.1093/sleep/zsae118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2024] [Revised: 04/23/2024] [Indexed: 05/26/2024] Open
Abstract
STUDY OBJECTIVES Sleep deprivation is a potential risk factor for metabolic diseases, including obesity and type 2 diabetes. We evaluated the impacts of moderate chronic sleep deprivation on glucose and lipid homeostasis in adult rats. METHODS Wistar rats (both sexes) were sleep-perturbed daily for 2 hours at the early (06:00-08:00) and the late light cycle (16:00-18:00) five days a week (except weekends) for 4 weeks. RESULTS Sleep perturbation (SP) resulted in reduced body weight gain in both sexes, associated with altered food intake and reduced adiposity. SP did not alter the short- or long-term memories or cause anxiogenic behavior. No major changes were observed in the plasma insulin, leptin, triacylglycerol, non-esterified fatty acids, and blood glucose upon SP. After SP, females exhibited a transitory glucose intolerance, while males became glucose intolerant at the end of the experimental period. Male rats also developed higher insulin sensitivity at the end of the SP protocol. Morphometric analyses revealed no changes in hepatic glycogen deposition, pancreatic islet mass, islet-cell distribution, or adrenal cortex thickness in SP rats from both sexes, except for lower adipocyte size compared with controls. We did not find homogeneous changes in the relative expression of circadian and metabolic genes in muscle or hepatic tissues from the SP rats. CONCLUSIONS Moderate chronic SP reduces visceral adiposity and causes glucose intolerance with a more pronounced impact on male rats, reinforcing the metabolic risks of exposure to sleep disturbances.
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Affiliation(s)
- Natália Stinghen Tonet
- Laboratory of Investigation in Chronic Diseases (LIDoC), Center of Biological Sciences, Federal University of Santa Catarina, Florianópolis, Brazil
- Graduate Program in Biochemistry, Center of Biological Sciences, Federal University of Santa Catarina, Florianópolis, Brazil
| | - Danilo Francisco da Silva Marçal
- Laboratory of Investigation in Chronic Diseases (LIDoC), Center of Biological Sciences, Federal University of Santa Catarina, Florianópolis, Brazil
| | - Flavia Natividade da Silva
- Laboratory of Investigation in Chronic Diseases (LIDoC), Center of Biological Sciences, Federal University of Santa Catarina, Florianópolis, Brazil
| | - Henver Simionato Brunetta
- Department of Biochemistry and Tissue Biology, Institute of Biology, Universidade Estadual de Campinas, Campinas, Brazil
| | - Marcelo Alves da Silva Mori
- Department of Biochemistry and Tissue Biology, Institute of Biology, Universidade Estadual de Campinas, Campinas, Brazil
| | - Gustavo Jorge Dos Santos
- Department of Physiological Sciences, Center of Biological Sciences, Federal University of Santa Catarina, Florianópolis, Brazil
| | - Eduardo Luiz Gasnhar Moreira
- Department of Physiological Sciences, Center of Biological Sciences, Federal University of Santa Catarina, Florianópolis, Brazil
| | - Alex Rafacho
- Laboratory of Investigation in Chronic Diseases (LIDoC), Center of Biological Sciences, Federal University of Santa Catarina, Florianópolis, Brazil
- Graduate Program in Biochemistry, Center of Biological Sciences, Federal University of Santa Catarina, Florianópolis, Brazil
- Department of Physiological Sciences, Center of Biological Sciences, Federal University of Santa Catarina, Florianópolis, Brazil
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4
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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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5
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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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6
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Fleishman JS, Kumar S. Bile acid metabolism and signaling in health and disease: molecular mechanisms and therapeutic targets. Signal Transduct Target Ther 2024; 9:97. [PMID: 38664391 PMCID: PMC11045871 DOI: 10.1038/s41392-024-01811-6] [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: 11/28/2023] [Revised: 03/06/2024] [Accepted: 03/17/2024] [Indexed: 04/28/2024] Open
Abstract
Bile acids, once considered mere dietary surfactants, now emerge as critical modulators of macronutrient (lipid, carbohydrate, protein) metabolism and the systemic pro-inflammatory/anti-inflammatory balance. Bile acid metabolism and signaling pathways play a crucial role in protecting against, or if aberrant, inducing cardiometabolic, inflammatory, and neoplastic conditions, strongly influencing health and disease. No curative treatment exists for any bile acid influenced disease, while the most promising and well-developed bile acid therapeutic was recently rejected by the FDA. Here, we provide a bottom-up approach on bile acids, mechanistically explaining their biochemistry, physiology, and pharmacology at canonical and non-canonical receptors. Using this mechanistic model of bile acids, we explain how abnormal bile acid physiology drives disease pathogenesis, emphasizing how ceramide synthesis may serve as a unifying pathogenic feature for cardiometabolic diseases. We provide an in-depth summary on pre-existing bile acid receptor modulators, explain their shortcomings, and propose solutions for how they may be remedied. Lastly, we rationalize novel targets for further translational drug discovery and provide future perspectives. Rather than dismissing bile acid therapeutics due to recent setbacks, we believe that there is immense clinical potential and a high likelihood for the future success of bile acid therapeutics.
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Affiliation(s)
- Joshua S Fleishman
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University, Queens, NY, USA
| | - Sunil Kumar
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University, Queens, NY, USA.
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7
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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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8
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Nguyen HT, Wiederkehr A, Wollheim CB, Park KS. Regulation of autophagy by perilysosomal calcium: a new player in β-cell lipotoxicity. Exp Mol Med 2024; 56:273-288. [PMID: 38297165 PMCID: PMC10907728 DOI: 10.1038/s12276-024-01161-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 10/16/2023] [Accepted: 11/09/2023] [Indexed: 02/02/2024] Open
Abstract
Autophagy is an essential quality control mechanism for maintaining organellar functions in eukaryotic cells. Defective autophagy in pancreatic beta cells has been shown to be involved in the progression of diabetes through impaired insulin secretion under glucolipotoxic stress. The underlying mechanism reveals the pathologic role of the hyperactivation of mechanistic target of rapamycin (mTOR), which inhibits lysosomal biogenesis and autophagic processes. Moreover, accumulating evidence suggests that oxidative stress induces Ca2+ depletion in the endoplasmic reticulum (ER) and cytosolic Ca2+ overload, which may contribute to mTOR activation in perilysosomal microdomains, leading to autophagic defects and β-cell failure due to lipotoxicity. This review delineates the antagonistic regulation of autophagic flux by mTOR and AMP-dependent protein kinase (AMPK) at the lysosomal membrane, and both of these molecules could be activated by perilysosomal calcium signaling. However, aberrant and persistent Ca2+ elevation upon lipotoxic stress increases mTOR activity and suppresses autophagy. Therefore, normalization of autophagy is an attractive therapeutic strategy for patients with β-cell failure and diabetes.
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Affiliation(s)
- Ha Thu Nguyen
- Department of Physiology, Yonsei University Wonju College of Medicine, Wonju, Korea
- Mitohormesis Research Center, Yonsei University Wonju College of Medicine, Wonju, Korea
| | | | - Claes B Wollheim
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland.
- Department of Clinical Sciences, Lund University, Malmö, Sweden.
| | - Kyu-Sang Park
- Department of Physiology, Yonsei University Wonju College of Medicine, Wonju, Korea.
- Mitohormesis Research Center, Yonsei University Wonju College of Medicine, Wonju, Korea.
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9
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Goldstein DS. Linking the Extended Autonomic System with the Homeostat Theory: New Perspectives about Dysautonomias. J Pers Med 2024; 14:123. [PMID: 38276245 PMCID: PMC10817591 DOI: 10.3390/jpm14010123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Revised: 01/14/2024] [Accepted: 01/20/2024] [Indexed: 01/27/2024] Open
Abstract
Dysautonomias are conditions in which altered functions of one or more components of the autonomic nervous system (ANS) adversely affect health. This essay is about how elucidating mechanisms of dysautonomias may rationalize personalized treatments. Emphasized here are two relatively new ideas-the "extended" autonomic system (EAS) and the "homeostat" theory as applied to the pathophysiology and potential treatments of dysautonomias. The recently promulgated concept of the EAS updates Langley's ANS to include neuroendocrine, immune/inflammatory, and central components. The homeostat theory builds on Cannon's theory of homeostasis by proposing the existence of comparators (e.g., a thermostat, glucostat, carbistat, barostat) that receive information about regulated variables (e.g., core temperature, blood glucose, blood gases, delivery of blood to the brain). Homeostats sense discrepancies between the information and response algorithms. The presentation links the EAS with the homeostat theory to understand pathophysiological mechanisms of dysautonomias. Feed-forward anticipatory processes shift input-output curves and maintain plateau levels of regulated variables within different bounds of values-"allostasis". Sustained allostatic processes increase long-term wear-and-tear on effectors and organs-allostatic load. They decreaseing thresholds for destabilizing and potentially fatal positive feedback loops. The homeostat theory enables mathematical models that define stress, allostasis, and allostatic load. The present discussion applies the EAS and homeostat concepts to specific examples of pediatric, adolescent/adult, and geriatric dysautonomias-familial dysautonomia, chronic orthostatic intolerance, and Lewy body diseases. Computer modeling has the potential to take into account the complexity and dynamics of allostatic processes and may yield testable predictions about individualized treatments and outcomes.
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Affiliation(s)
- David S Goldstein
- Autonomic Medicine Section, Clinical Neurosciences Program, Division of Intramural Research, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
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10
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Moustaki M, Paschou SA, Vakali E, Xekouki P, Ntali G, Kassi E, Peppa M, Psaltopoulou T, Tzanela M, Vryonidou A. Secondary diabetes mellitus in pheochromocytomas and paragangliomas. Endocrine 2023; 82:467-479. [PMID: 37731140 PMCID: PMC10618385 DOI: 10.1007/s12020-023-03492-7] [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: 06/28/2023] [Accepted: 08/10/2023] [Indexed: 09/22/2023]
Abstract
Secondary diabetes mellitus (DM) in secretory pheochromocytomas and paragangliomas (PPGLs) is encountered in up to 50% of cases, with its presentation ranging from mild, insulin resistant forms to profound insulin deficiency states, such as diabetic ketoacidosis and hyperglycemic hyperosmolar state. PPGLs represent hypermetabolic states, in which adrenaline and noradrenaline induce insulin resistance in target tissues characterized by aerobic glycolysis, excessive lipolysis, altered adipokine expression, subclinical inflammation, as well as enhanced gluconeogenesis and glucogenolysis. These effects are mediated both directly, upon adrenergic receptor stimulation, and indirectly, via increased glucagon secretion. Impaired insulin secretion is the principal pathogenetic mechanism of secondary DM in this setting; yet, this is relevant for tumors with adrenergic phenotype, arising from direct inhibitory actions in beta pancreatic cells and incretin effect impairment. In contrast, insulin secretion might be enhanced in tumors with noradrenergic phenotype. This dimorphic effect might correspond to two distinct glycemic phenotypes, with predominant insulin resistance and insulin deficiency respectively. Secondary DM improves substantially post-surgery, with up to 80% remission rate. The fact that surgical treatment of PPGLs restores insulin sensitivity and secretion at greater extent compared to alpha and beta blockade, implies the existence of further, non-adrenergic mechanisms, possibly involving other hormonal co-secretion by these tumors. DM management in PPGLs is scarcely studied. The efficacy and safety of newer anti-diabetic medications, such as glucagon-like peptide 1 receptor agonists and sodium glucose cotransporter 2 inhibitors (SGLT2is), as well as potential disease-modifying roles of metformin and SGLT2is warrant further investigation in future studies.
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Affiliation(s)
- Melpomeni Moustaki
- Department of Endocrinology and Diabetes Center, Hellenic Red Cross Hospital, Athens, Greece
| | - Stavroula A Paschou
- Endocrine Unit and Diabetes Center, Department of Clinical Therapeutics, Alexandra Hospital, School of Medicine, National and Kapodistrian University of Athens, Athens, Greece.
| | - Elena Vakali
- Department of Endocrinology and Diabetes Center, Hellenic Red Cross Hospital, Athens, Greece
| | - Paraskevi Xekouki
- Department of Endocrinology and Diabetes, University General Hospital of Heraklion, School of Medicine, University of Crete, Heraklion, Greece
| | - Georgia Ntali
- Department of Endocrinology and Diabetes Center, Endo ERN Center, Evaggelismos Hospital, Athens, Greece
| | - Evanthia Kassi
- Endocrine Unit, First Department of Propaedeutic and Internal Medicine, Laiko Hospital, School of Medicine, National and Kapodistrian University of Athens, Athens, Greece
| | - Melpomeni Peppa
- Endocrine Unit and Diabetes Center, Second Department of Internal Medicine, Attikon University Hospital, School of Medicine, National and Kapodistrian University of Athens, Athens, Greece
| | - Theodora Psaltopoulou
- Endocrine Unit and Diabetes Center, Department of Clinical Therapeutics, Alexandra Hospital, School of Medicine, National and Kapodistrian University of Athens, Athens, Greece
| | - Marinella Tzanela
- Department of Endocrinology and Diabetes Center, Endo ERN Center, Evaggelismos Hospital, Athens, Greece
| | - Andromachi Vryonidou
- Department of Endocrinology and Diabetes Center, Hellenic Red Cross Hospital, Athens, Greece
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11
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Ogunkunle EO, Davis JJ, Skinner EL, Thornham J, Roper MG. Analysis of D-amino acids secreted from murine islets of Langerhans using Marfey's reagent and reversed phase LC-MS/MS. J Chromatogr B Analyt Technol Biomed Life Sci 2023; 1231:123928. [PMID: 37976942 PMCID: PMC10843809 DOI: 10.1016/j.jchromb.2023.123928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 10/22/2023] [Accepted: 11/08/2023] [Indexed: 11/19/2023]
Abstract
D-amino acids (D-AAs) are important signaling molecules due to their ability to bind ionotropic N-methyl-D-aspartate receptors. D-serine (D-Ser), D-alanine (D-Ala), and D-aspartate (D-Asp) have been found individually in the endocrine portion of the pancreas, the islets of Langerhans, and/or their secretions. However, there has been no report of a comprehensive assessment of D-AAs in islet secretions. To evaluate the release of these compounds, the effectiveness of both 1-(9-fluorenyl)-ethyl chloroformate (FLEC reagent) and 1-fluoro-2,4-dinitrophenyl-5-L-alanine amide (Marfey's reagent, MR) in separation of D/L-AA enantiomeric pairs in islet-specific buffers were evaluated. MR-derivatized D/L AAs showed greater than baseline resolution (Rs ≥ 1.5) of 13 enantiomeric pairs when using a non-linear gradient and an acidic mobile phase system, while FLEC-derivatized AAs exhibited limited resolution on both biphenyl and C18 columns. The optimized MR method yielded highly reproducible separations with retention times less than 1% RSD. Excellent linearity between the analyte concentrations and response (R2 > 0.98) were obtained, with less than 15% RSD for all analyte responses. Most analytes had an LOD at or below 100 nM, except for L-Ala (200 nM). The optimized MR method was used to quantify D-AAs in secretions of 150 murine islets after incubation in 3- and 20-mM glucose. In response to both solutions, D-Ser and D-glutamine were tentatively identified via comparison of retention time and quantifier-to-qualifer ion ratios with standards, and from spiking experiments. Both were secreted in low quantities which did not differ significantly in either low (D-Ser: 44 ± 2 fmol islet-1h-1; D-Gln: 300 ± 100 fmol islet-1h-1) or high (D-Ser: 23 ± 1 fmol islet-1h-1; D-Gln: 120 ± 50 fmol islet-1h-1) glucose across 3 biological replicates. The method developed is robust and can be applied to further examine the release of D-AAs and their potential roles in islet physiology.
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Affiliation(s)
- Emmanuel O Ogunkunle
- Department of Chemistry and Biochemistry, Florida State University, 95 Chieftain Way, Tallahassee, FL 32306, United States
| | - Joshua J Davis
- Department of Chemistry and Biochemistry, Florida State University, 95 Chieftain Way, Tallahassee, FL 32306, United States
| | - Emily L Skinner
- Department of Chemistry and Biochemistry, Florida State University, 95 Chieftain Way, Tallahassee, FL 32306, United States
| | - James Thornham
- Program in Molecular Biophysics, Florida State University, 95 Chieftain Way, Tallahassee, FL 32306, United States
| | - Michael G Roper
- Department of Chemistry and Biochemistry, Florida State University, 95 Chieftain Way, Tallahassee, FL 32306, United States; Program in Molecular Biophysics, Florida State University, 95 Chieftain Way, Tallahassee, FL 32306, United States.
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12
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Pettway YD, Saunders DC, Brissova M. The human α cell in health and disease. J Endocrinol 2023; 258:e220298. [PMID: 37114672 PMCID: PMC10428003 DOI: 10.1530/joe-22-0298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 04/27/2023] [Indexed: 04/29/2023]
Abstract
In commemoration of 100 years since the discovery of glucagon, we review current knowledge about the human α cell. Alpha cells make up 30-40% of human islet endocrine cells and play a major role in regulating whole-body glucose homeostasis, largely through the direct actions of their main secretory product - glucagon - on peripheral organs. Additionally, glucagon and other secretory products of α cells, namely acetylcholine, glutamate, and glucagon-like peptide-1, have been shown to play an indirect role in the modulation of glucose homeostasis through autocrine and paracrine interactions within the islet. Studies of glucagon's role as a counterregulatory hormone have revealed additional important functions of the α cell, including the regulation of multiple aspects of energy metabolism outside that of glucose. At the molecular level, human α cells are defined by the expression of conserved islet-enriched transcription factors and various enriched signature genes, many of which have currently unknown cellular functions. Despite these common threads, notable heterogeneity exists amongst human α cell gene expression and function. Even greater differences are noted at the inter-species level, underscoring the importance of further study of α cell physiology in the human context. Finally, studies on α cell morphology and function in type 1 and type 2 diabetes, as well as other forms of metabolic stress, reveal a key contribution of α cell dysfunction to dysregulated glucose homeostasis in disease pathogenesis, making targeting the α cell an important focus for improving treatment.
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Affiliation(s)
- Yasminye D. Pettway
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, 37232, USA
| | - Diane C. Saunders
- Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, 37232, USA
| | - Marcela Brissova
- Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, 37232, USA
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13
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Turbitt J, Brennan L, Moffett RC, Flatt PR, Johnson PRV, Tarasov AI, McClenaghan NH. NKCC transport mediates the insulinotropic effects of taurine and other small neutral amino acids. Life Sci 2023; 316:121402. [PMID: 36669678 DOI: 10.1016/j.lfs.2023.121402] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2022] [Revised: 01/04/2023] [Accepted: 01/13/2023] [Indexed: 01/19/2023]
Abstract
AIMS Despite its high concentration in pancreatic islets of Langerhans and broad range of antihyperglycemic effects, the route facilitating the import of dietary taurine into pancreatic β-cell and mechanisms underlying its insulinotropic activity are unclear. We therefore studied the impact of taurine on beta-cell function, alongside that of other small neutral amino acids, L-alanine and L-proline. MAIN METHODS Pharmacological profiling of insulin secretion was conducted using clonal BRIN BD11 β-cells, the impact of taurine on the metabolic fate of glucose carbons was assessed using NMR and the findings were verified by real-time imaging of Ca2+ dynamics in the cytosol of primary mouse and human islet beta-cells. KEY FINDINGS In our hands, taurine, alanine and proline induced secretory responses that were dependent on the plasma membrane depolarisation, import of Ca2+, homeostasis of K+ and Na+ as well as on cell glycolytic and oxidative metabolism. Taurine shifted the balance between the oxidation and anaplerosis towards the latter, in BRIN BD11 beta-cells. Furthermore, the amino acid signalling was significantly attenuated by inhibition of Na+-K+-Cl- symporter (NKCC). SIGNIFICANCE These data suggest that taurine, like L-alanine and L-proline, acutely induces glucose-dependent insulin-secretory responses by modulating electrogenic Na+ transport, with potential role of intracellular K+ and Cl- in the signal transduction. The acute action delineated would be consistent with antidiabetic potential of dietary taurine supplementation.
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Affiliation(s)
- Julie Turbitt
- School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine BT52 1SA, UK
| | - Lorraine Brennan
- UCD Institute of Food and Health, UCD School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Ireland; UCD Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland.
| | - R Charlotte Moffett
- School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine BT52 1SA, UK.
| | - Peter R Flatt
- School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine BT52 1SA, UK.
| | - Paul R V Johnson
- Nuffeld Department of Surgical Sciences, Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Headington, OX3 7LE Oxford, UK; Oxford Biomedical Research Centre (OxBRC), UK.
| | - Andrei I Tarasov
- School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine BT52 1SA, UK; Nuffeld Department of Surgical Sciences, Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Headington, OX3 7LE Oxford, UK; Oxford Biomedical Research Centre (OxBRC), UK.
| | - Neville H McClenaghan
- School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine BT52 1SA, UK; Department of Life Sciences, Atlantic Technological University, Ash Lane, Sligo, F91 YW50, Ireland.
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14
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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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15
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Viloria K, Nasteska D, Ast J, Hasib A, Cuozzo F, Heising S, Briant LJB, Hewison M, Hodson DJ. GC-Globulin/Vitamin D-Binding Protein Is Required for Pancreatic α-Cell Adaptation to Metabolic Stress. Diabetes 2023; 72:275-289. [PMID: 36445949 DOI: 10.2337/db22-0326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 11/14/2022] [Indexed: 12/02/2022]
Abstract
GC-globulin (GC), or vitamin D-binding protein, is a multifunctional protein involved in the transport of circulating vitamin 25(OH)D and fatty acids, as well as actin scavenging. In the pancreatic islets, the gene encoding GC, GC/Gc, is highly localized to glucagon-secreting α-cells. Despite this, the role of GC in α-cell function is poorly understood. We previously showed that GC is essential for α-cell morphology, electrical activity, and glucagon secretion. We now show that loss of GC exacerbates α-cell failure during metabolic stress. High-fat diet-fed GC-/- mice have basal hyperglucagonemia, which is associated with decreased α-cell size, impaired glucagon secretion and Ca2+ fluxes, and changes in glucose-dependent F-actin remodelling. Impairments in glucagon secretion can be rescued using exogenous GC to replenish α-cell GC levels, increase glucagon granule area, and restore the F-actin cytoskeleton. Lastly, GC levels decrease in α-cells of donors with type 2 diabetes, which is associated with changes in α-cell mass, morphology, and glucagon expression. Together, these data demonstrate an important role for GC in α-cell adaptation to metabolic stress.
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Affiliation(s)
- Katrina Viloria
- Institute of Metabolism and Systems Research (IMSR), and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, U.K
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, U.K
| | - Daniela Nasteska
- Institute of Metabolism and Systems Research (IMSR), and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, U.K
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, U.K
| | - Julia Ast
- Institute of Metabolism and Systems Research (IMSR), and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, U.K
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, U.K
| | - Annie Hasib
- Institute of Metabolism and Systems Research (IMSR), and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, U.K
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, U.K
| | - Federica Cuozzo
- Institute of Metabolism and Systems Research (IMSR), and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, U.K
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, U.K
| | - Silke Heising
- Institute of Metabolism and Systems Research (IMSR), and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, U.K
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, U.K
| | - Linford J B Briant
- Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), National Institute for Health Research (NIHR) Oxford Biomedical Research Centre, Churchill Hospital, Radcliffe Department of Medicine, University of Oxford, Oxford, U.K
| | - Martin Hewison
- Institute of Metabolism and Systems Research (IMSR), and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, U.K
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, U.K
| | - David J Hodson
- Institute of Metabolism and Systems Research (IMSR), and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, U.K
- Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, U.K
- Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), National Institute for Health Research (NIHR) Oxford Biomedical Research Centre, Churchill Hospital, Radcliffe Department of Medicine, University of Oxford, Oxford, U.K
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16
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Sarnobat D, Moffett RC, Ma J, Flatt PR, McClenaghan NH, Tarasov AI. Taurine rescues pancreatic β-cell stress by stimulating α-cell transdifferentiation. Biofactors 2023. [PMID: 36714992 DOI: 10.1002/biof.1938] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 01/05/2023] [Indexed: 01/31/2023]
Abstract
The semi-essential ubiquitous amino acid taurine has been shown to alleviate obesity and hyperglycemia in humans; however, the pathways underlying the antidiabetic actions have not been characterized. We explored the effect of chronic taurine exposure on cell biology of pancreatic islets, in degenerative type 1-like diabetes. The latter was modeled by small dose of streptozotocin (STZ) injection for 5 days in mice, followed by a 10-day administration of taurine (2% w/v, orally) in the drinking water. Taurine treatment opposed the detrimental changes in islet morphology and β-/α-cell ratio, induced by STZ diabetes, coincidentally with a significant 3.9 ± 0.7-fold enhancement of proliferation and 40 ± 5% reduction of apoptosis in β-cells. In line with these findings, the treatment counteracted an upregulation of antioxidant (Sod1, Sod2, Cat, Gpx1) and downregulation of islet expansion (Ngn3, Itgb1) genes induced by STZ, in a pancreatic β-cell line. At the same time, taurine enhanced the transdifferentiation of α-cells into β-cells by 2.3 ± 0.8-fold, echoed in strong non-metabolic elevation of cytosolic Ca2+ levels in pancreatic α-cells. Our data suggest a bimodal effect of dietary taurine on islet β-cell biology, which combines the augmentation of α-/β-cell transdifferentiation with downregulation of apoptosis. The dualism of action, stemming presumably from the intra- and extracellular modality of the signal, is likely to explain the antidiabetic potential of taurine supplementation.
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Affiliation(s)
- Dipak Sarnobat
- School of Biomedical Sciences, Ulster University, Coleraine, UK
| | | | - Jinfang Ma
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK
| | - Peter R Flatt
- School of Biomedical Sciences, Ulster University, Coleraine, UK
| | - Neville H McClenaghan
- School of Biomedical Sciences, Ulster University, Coleraine, UK
- Department of Life Sciences, Atlantic Technological University, Sligo, Ireland
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17
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Riederer E, Cang C, Ren D. Lysosomal Ion Channels: What Are They Good For and Are They Druggable Targets? Annu Rev Pharmacol Toxicol 2023; 63:19-41. [PMID: 36151054 DOI: 10.1146/annurev-pharmtox-051921-013755] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Lysosomes play fundamental roles in material digestion, cellular clearance, recycling, exocytosis, wound repair, Ca2+ signaling, nutrient signaling, and gene expression regulation. The organelle also serves as a hub for important signaling networks involving the mTOR and AKT kinases. Electrophysiological recording and molecular and structural studies in the past decade have uncovered several unique lysosomal ion channels and transporters, including TPCs, TMEM175, TRPMLs, CLN7, and CLC-7. They underlie the organelle's permeability to major ions, including K+, Na+, H+, Ca2+, and Cl-. The channels are regulated by numerous cellular factors, ranging from H+ in the lumen and voltage across the lysosomal membrane to ATP in the cytosol to growth factors outside the cell. Genetic variations in the channel/transporter genes are associated with diseases that include lysosomal storage diseases and neurodegenerative diseases. Recent studies with human genetics and channel activators suggest that lysosomal channels may be attractive targets for the development of therapeutics for the prevention of and intervention in human diseases.
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Affiliation(s)
- Erika Riederer
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, USA; ,
| | - Chunlei Cang
- CAS Key Laboratory of Innate Immunity and Chronic Disease, Neurodegenerative Disorder Research Center, School of Basic Medical Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, China;
| | - Dejian Ren
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, USA; ,
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18
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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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19
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Abstract
The discovery of NAADP-evoked Ca2+ release in sea urchin eggs and then as a ubiquitous Ca2+ mobilizing messenger has introduced several novel paradigms to our understanding of Ca2+ signalling, not least in providing a link between cell stimulation and Ca2+ release from lysosomes and other acidic Ca2+ storage organelles. In addition, the hallmark concentration-response relationship of NAADP-mediated Ca2+ release, shaped by striking activation/desensitization mechanisms, influences its actions as an intracellular messenger. There has been recent progress in our understanding of the molecular mechanisms underlying NAADP-evoked Ca2+ release, such as the identification of the endo-lysosomal two-pore channel family of cation channels (TPCs) as their principal target and the identity of NAADP-binding proteins that complex with them. The NAADP/TPC signalling axis has gained recent prominence in pathophysiology for their roles in such disease processes as neurodegeneration, tumorigenesis and cellular viral entry.
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Affiliation(s)
- Antony Galione
- Department of Pharmacology, University of Oxford, Oxford, UK.
| | - Lianne C Davis
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Lora L Martucci
- Department of Pharmacology, University of Oxford, Oxford, UK
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20
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Matsuo Y, Ashida K, Nagayama A, Moritaka K, Gobaru M, Yasuda J, Ogasawara N, Kurose H, Chikui K, Iwata S, Inoguchi Y, Hasuzawa N, Motomura S, Igawa T, Nomura M. Metyrosine-associated endocrinological changes in pheochromocytoma and paraganglioma. ENDOCRINE ONCOLOGY (BRISTOL, ENGLAND) 2023; 3:e230006. [PMID: 37822367 PMCID: PMC10563611 DOI: 10.1530/eo-23-0006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Accepted: 08/29/2023] [Indexed: 10/13/2023]
Abstract
Objective Metyrosine (alpha-methyl-para-tyrosine) effectively reduces catecholamine levels in patients with pheochromocytoma/paraganglioma. However, improvements in physiological and metabolic parameters and changes in endocrine function associated with metyrosine administration should be validated in comparison to surgery. This study was performed to confirm the effects of metyrosine on the physiological, metabolic, and endocrinological functions of patients with pheochromocytoma/paraganglioma in the perioperative period. Design This retrospective cohort study was performed at a single university hospital. Methods We included ten patients with pheochromocytoma/paraganglioma who received oral metyrosine after α-blocker therapy and consecutive surgeries. Urinary catecholamine metabolite levels and other clinical parameters were evaluated before and after metyrosine administration, and 1 week after surgery. Results The mean age was 53.1 ± 16.1 years. Of the ten participants (four men and six women), nine had pheochromocytoma and one had paraganglioma. The median maximum metyrosine dose was 750 mg/day. Urinary catecholamine metabolite levels significantly decreased in a dose-dependent manner after metyrosine administration. Both systolic and diastolic blood pressure significantly decreased after metyrosine and surgical treatment. Metyrosine administration significantly improved insulin sensitivity, although surgery improved the the basal insulin secretion. Additionally, serum prolactin and thyroid-stimulatory hormone levels were significantly increased by metyrosine treatment, whereas plasma renin activity was decreased. Conclusions Metyrosine significantly reduced catecholamines in patients with pheochromocytoma/paraganglioma and ensured the safety of the surgery. Adjustment of metyrosine administration may make surgical pretreatment more effective in achieving stabilized blood pressure and improving glucose metabolism. Endocrine parameters may manifest as the systemic effects of metyrosine administration.
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Affiliation(s)
- Yuko Matsuo
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kurume University School of Medicine, Asahi-machi, Kurume, Fukuoka, Japan
| | - Kenji Ashida
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kurume University School of Medicine, Asahi-machi, Kurume, Fukuoka, Japan
| | - Ayako Nagayama
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kurume University School of Medicine, Asahi-machi, Kurume, Fukuoka, Japan
| | - Kanoko Moritaka
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kurume University School of Medicine, Asahi-machi, Kurume, Fukuoka, Japan
| | - Mizuki Gobaru
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kurume University School of Medicine, Asahi-machi, Kurume, Fukuoka, Japan
| | - Junichi Yasuda
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kurume University School of Medicine, Asahi-machi, Kurume, Fukuoka, Japan
| | - Naoyuki Ogasawara
- Department of Urology, Kurume University School of Medicine, Asahi-machi, Kurume, Fukuoka, Japan
| | - Hirofumi Kurose
- Department of Urology, Kurume University School of Medicine, Asahi-machi, Kurume, Fukuoka, Japan
| | - Katsuaki Chikui
- Department of Urology, Kurume University School of Medicine, Asahi-machi, Kurume, Fukuoka, Japan
| | - Shimpei Iwata
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kurume University School of Medicine, Asahi-machi, Kurume, Fukuoka, Japan
| | - Yukihiro Inoguchi
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kurume University School of Medicine, Asahi-machi, Kurume, Fukuoka, Japan
| | - Nao Hasuzawa
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kurume University School of Medicine, Asahi-machi, Kurume, Fukuoka, Japan
| | - Seiichi Motomura
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kurume University School of Medicine, Asahi-machi, Kurume, Fukuoka, Japan
| | - Tsukasa Igawa
- Department of Urology, Kurume University School of Medicine, Asahi-machi, Kurume, Fukuoka, Japan
| | - Masatoshi Nomura
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kurume University School of Medicine, Asahi-machi, Kurume, Fukuoka, Japan
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21
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Sarnobat D, Lafferty RA, Charlotte Moffett R, Tarasov AI, Flatt PR, Irwin N. Effects of artemether on pancreatic islet morphology, islet cell turnover and α-cell transdifferentiation in insulin-deficient GluCreERT2;ROSA26-eYFP diabetic mice. J Pharm Pharmacol 2022; 74:1758-1764. [PMID: 36206181 DOI: 10.1093/jpp/rgac075] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 09/05/2022] [Indexed: 01/26/2023]
Abstract
OBJECTIVES The antimalarial drug artemether is suggested to effect pancreatic islet cell transdifferentiation, presumably through activation γ-aminobutyric acid receptors, but this biological action is contested. METHODS We have investigated changes in α-cell lineage in response to 10-days treatment with artemether (100 mg/kg oral, once daily) on a background of β-cell stress induced by multiple low-dose streptozotocin (STZ) injection in GluCreERT2; ROSA26-eYFP transgenic mice. KEY FINDINGS Artemether intervention did not affect the actions of STZ on body weight, food and fluid intake or blood glucose. Circulating insulin and glucagon were reduced by STZ treatment, with a corresponding decline in pancreatic insulin content, which were not altered by artemether. The detrimental changes to pancreatic islet morphology induced by STZ were also evident in artemether-treated mice. Tracing of α-cell lineage, through co-staining for glucagon and yellow fluorescent protein (YFP), revealed a significant decrease of the proportion of glucagon+YFP- cells in STZ-diabetic mice, which was reversed by artemether. However, artemether had no effect on transdifferentiation of α-cells into β-cells and failed to augment the number of bi-hormonal, insulin+glucagon+, islet cells. CONCLUSIONS Our observations confirm that artemisinin derivatives do not impart meaningful benefits on islet cell lineage transition events or pancreatic islet morphology.
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Affiliation(s)
- Dipak Sarnobat
- Biomedical Sciences Research Institute, Centre for Diabetes, Ulster University, Coleraine, UK
| | - Ryan A Lafferty
- Biomedical Sciences Research Institute, Centre for Diabetes, Ulster University, Coleraine, UK
| | - R Charlotte Moffett
- Biomedical Sciences Research Institute, Centre for Diabetes, Ulster University, Coleraine, UK
| | - Andrei I Tarasov
- Biomedical Sciences Research Institute, Centre for Diabetes, Ulster University, Coleraine, UK
| | - Peter R Flatt
- Biomedical Sciences Research Institute, Centre for Diabetes, Ulster University, Coleraine, UK
| | - Nigel Irwin
- Biomedical Sciences Research Institute, Centre for Diabetes, Ulster University, Coleraine, UK
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22
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Hampton RF, Jimenez-Gonzalez M, Stanley SA. Unravelling innervation of pancreatic islets. Diabetologia 2022; 65:1069-1084. [PMID: 35348820 PMCID: PMC9205575 DOI: 10.1007/s00125-022-05691-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 02/08/2022] [Indexed: 01/05/2023]
Abstract
The central and peripheral nervous systems play critical roles in regulating pancreatic islet function and glucose metabolism. Over the last century, in vitro and in vivo studies along with examination of human pancreas samples have revealed the structure of islet innervation, investigated the contribution of sympathetic, parasympathetic and sensory neural pathways to glucose control, and begun to determine how the structure and function of pancreatic nerves are disrupted in metabolic disease. Now, state-of-the art techniques such as 3D imaging of pancreatic innervation and targeted in vivo neuromodulation provide further insights into the anatomy and physiological roles of islet innervation. Here, we provide a summary of the published work on the anatomy of pancreatic islet innervation, its roles, and evidence for disordered islet innervation in metabolic disease. Finally, we discuss the possibilities offered by new technologies to increase our knowledge of islet innervation and its contributions to metabolic regulation.
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Affiliation(s)
- Rollie F Hampton
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Maria Jimenez-Gonzalez
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Sarah A Stanley
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
- Nash Family Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
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23
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Dong X, Chen Y, Lu J, Huang S, Pei G. β-arrestin 2 and Epac2 cooperatively mediate DRD1-stimulated proliferation of human neural stem cells and growth of human cerebral organoids. Stem Cells 2022; 40:857-869. [PMID: 35772103 DOI: 10.1093/stmcls/sxac046] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 06/15/2022] [Indexed: 11/12/2022]
Abstract
G protein coupled receptors (GPCRs) reportedly relay specific signals, such as dopamine and serotonin, to regulate neurogenic processes though the underlying signaling pathways are not fully elucidated. Based on our previous work which demonstrated Dopamine receptor D1 (DRD1) effectively induces the proliferation of human neural stem cells, here we continued to show the knockout of β-arrestin 2 by CRISPR/Cas9 technology significantly weakened the DRD1-induced proliferation and neurosphere growth. Furthermore, inhibition of the downstream p38 MAPK by its specific inhibitors or small hairpin RNA mimicked the weakening effect of β-arrestin 2 knockout. In addition, blocking of Epac2, a PKA independent signal pathway, by its specific inhibitors or small hairpin RNA also significantly reduced DRD1-induced effects. Simultaneous inhibition of β-arrestin 2/p38 MAPK and Epac2 pathways nearly abolished the DRD1-stimulated neurogenesis, indicating the cooperative contribution of both pathways. Consistently, the expansion and folding of human cerebral organoids as stimulated by DRD1 were also mediated cooperatively by both β-arrestin 2/p38 MAPK and Epac2 pathways. Taken together, our results reveal that GPCRs apply at least two different signal pathways to regulate neurogenic processes in a delicate and balanced manners.
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Affiliation(s)
- Xiaoxu Dong
- School of Life Science and Technology, Shanghai Tech University, Shanghai, China.,State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China
| | - Yujie Chen
- Uli Schwarz Quantitative Biology Core Facility, Bio-Med Big Data Center, CAS Key Laboratory of Computational Biology, Shanghai Institute of Nutrition and Health, Chinese Academy of Sciences, Shanghai, China
| | - Juan Lu
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China
| | - Shichao Huang
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China
| | - Gang Pei
- School of Life Science and Technology, Shanghai Tech University, Shanghai, China.,State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China.,Shanghai Key Laboratory of Signaling and Disease Research, Collaborative Innovation Center for Brain Science, School of Life Sciences and Technology, Tongji University, Shanghai, China.,Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing, China
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24
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Khan D, Moffett RC, Flatt PR, Tarasov AI. Classical and non-classical islet peptides in the control of β-cell function. Peptides 2022; 150:170715. [PMID: 34958851 DOI: 10.1016/j.peptides.2021.170715] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 11/25/2021] [Accepted: 12/17/2021] [Indexed: 12/25/2022]
Abstract
The dual role of the pancreas as both an endocrine and exocrine gland is vital for food digestion and control of nutrient metabolism. The exocrine pancreas secretes enzymes into the small intestine aiding digestion of sugars and fats, whereas the endocrine pancreas secretes a cocktail of hormones into the blood, which is responsible for blood glucose control and regulation of carbohydrate, protein and fat metabolism. Classical islet hormones, insulin, glucagon, pancreatic polypeptide and somatostatin, interact in an autocrine and paracrine manner, to fine-tube the islet function and insulin secretion to the needs of the body. Recently pancreatic islets have been reported to express a number of non-classical peptide hormones involved in metabolic signalling, whose major production site was believed to reside outside pancreas, e.g. in the small intestine. We highlight the key non-classical islet peptides, and consider their involvement, together with established islet hormones, in regulation of stimulus-secretion coupling as well as proliferation, survival and transdifferentiation of β-cells. We furthermore focus on the paracrine interaction between classical and non-classical islet hormones in the maintenance of β-cell function. Understanding the functional relationships between these islet peptides might help to develop novel, more efficient treatments for diabetes and related metabolic disorders.
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Affiliation(s)
- Dawood Khan
- Biomedical Sciences Research Institute, School of Biomedical Sciences, Ulster University, Coleraine, Northern Ireland, UK.
| | - R Charlotte Moffett
- Biomedical Sciences Research Institute, School of Biomedical Sciences, Ulster University, Coleraine, Northern Ireland, UK
| | - Peter R Flatt
- Biomedical Sciences Research Institute, School of Biomedical Sciences, Ulster University, Coleraine, Northern Ireland, UK
| | - Andrei I Tarasov
- Biomedical Sciences Research Institute, School of Biomedical Sciences, Ulster University, Coleraine, Northern Ireland, UK
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25
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Singh B, Khattab F, Gilon P. Glucose inhibits glucagon secretion by decreasing [Ca2+]c and by reducing the efficacy of Ca2+ on exocytosis via somatostatin-dependent and independent mechanisms. Mol Metab 2022; 61:101495. [PMID: 35421610 PMCID: PMC9065434 DOI: 10.1016/j.molmet.2022.101495] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 03/15/2022] [Accepted: 04/04/2022] [Indexed: 11/15/2022] Open
Abstract
Objective Methods Results Conclusions Glucose modulates [Ca2+]c in α-cells within islets but not in dispersed α-cells. In α-cells within islets, it decreases [Ca2+]c independently of their KATP channels. It decreases α-cell [Ca2+]c partly via somatostatin. All glucose-induced [Ca2+]c changes trigger parallel changes in glucagon release. Glucose also decreases the efficacy of Ca2+ on exocytosis (attenuating pathway).
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Affiliation(s)
- Bilal Singh
- Université Catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle d'Endocrinologie, Diabète et Nutrition, Brussels, Belgium
| | - Firas Khattab
- Université Catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle d'Endocrinologie, Diabète et Nutrition, Brussels, Belgium
| | - Patrick Gilon
- Université Catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle d'Endocrinologie, Diabète et Nutrition, Brussels, Belgium.
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26
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Acetyl-CoA-carboxylase 1 (ACC1) plays a critical role in glucagon secretion. Commun Biol 2022; 5:238. [PMID: 35304577 PMCID: PMC8933412 DOI: 10.1038/s42003-022-03170-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 02/08/2022] [Indexed: 11/09/2022] Open
Abstract
Dysregulated glucagon secretion from pancreatic alpha-cells is a key feature of type-1 and type-2 diabetes (T1D and T2D), yet our mechanistic understanding of alpha-cell function is underdeveloped relative to insulin-secreting beta-cells. Here we show that the enzyme acetyl-CoA-carboxylase 1 (ACC1), which couples glucose metabolism to lipogenesis, plays a key role in the regulation of glucagon secretion. Pharmacological inhibition of ACC1 in mouse islets or αTC9 cells impaired glucagon secretion at low glucose (1 mmol/l). Likewise, deletion of ACC1 in alpha-cells in mice reduced glucagon secretion at low glucose in isolated islets, and in response to fasting or insulin-induced hypoglycaemia in vivo. Electrophysiological recordings identified impaired KATP channel activity and P/Q- and L-type calcium currents in alpha-cells lacking ACC1, explaining the loss of glucose-sensing. ACC-dependent alterations in S-acylation of the KATP channel subunit, Kir6.2, were identified by acyl-biotin exchange assays. Histological analysis identified that loss of ACC1 caused a reduction in alpha-cell area of the pancreas, glucagon content and individual alpha-cell size, further impairing secretory capacity. Loss of ACC1 also reduced the release of glucagon-like peptide 1 (GLP-1) in primary gastrointestinal crypts. Together, these data reveal a role for the ACC1-coupled pathway in proglucagon-expressing nutrient-responsive endocrine cell function and systemic glucose homeostasis.
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27
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Sarnobat D, Charlotte Moffett R, Flatt PR, Irwin N, Tarasov AI. GABA and insulin but not nicotinamide augment α- to β-cell transdifferentiation in insulin-deficient diabetic mice. Biochem Pharmacol 2022; 199:115019. [DOI: 10.1016/j.bcp.2022.115019] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 03/23/2022] [Accepted: 03/23/2022] [Indexed: 12/30/2022]
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28
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Skelding KA, Barry DL, Theron DZ, Lincz LF. Targeting the two-pore channel 2 in cancer progression and metastasis. EXPLORATION OF TARGETED ANTI-TUMOR THERAPY 2022; 3:62-89. [PMID: 36046356 PMCID: PMC9400767 DOI: 10.37349/etat.2022.00072] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 02/02/2022] [Indexed: 11/19/2022] Open
Abstract
The importance of Ca2+ signaling, and particularly Ca2+ channels, in key events of cancer cell function such as proliferation, metastasis, autophagy and angiogenesis, has recently begun to be appreciated. Of particular note are two-pore channels (TPCs), a group of recently identified Ca2+-channels, located within the endolysosomal system. TPC2 has recently emerged as an intracellular ion channel of significant pathophysiological relevance, specifically in cancer, and interest in its role as an anti-cancer drug target has begun to be explored. Herein, an overview of the cancer-related functions of TPC2 and a discussion of its potential as a target for therapeutic intervention, including a summary of clinical trials examining the TPC2 inhibitors, naringenin, tetrandrine, and verapamil for the treatment of various cancers is provided.
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Affiliation(s)
- Kathryn A. Skelding
- Cancer Cell Biology Research Group, School of Biomedical Sciences and Pharmacy, College of Health, Medicine and Wellbeing, The University of Newcastle, Callaghan, New South Wales 2308, Australia;Hunter Medical Research Institute, New Lambton Heights, New South Wales 2305, Australia
| | - Daniel L. Barry
- Cancer Cell Biology Research Group, School of Biomedical Sciences and Pharmacy, College of Health, Medicine and Wellbeing, The University of Newcastle, Callaghan, New South Wales 2308, Australia;Hunter Medical Research Institute, New Lambton Heights, New South Wales 2305, Australia
| | - Danielle Z. Theron
- Cancer Cell Biology Research Group, School of Biomedical Sciences and Pharmacy, College of Health, Medicine and Wellbeing, The University of Newcastle, Callaghan, New South Wales 2308, Australia;Hunter Medical Research Institute, New Lambton Heights, New South Wales 2305, Australia
| | - Lisa F. Lincz
- Cancer Cell Biology Research Group, School of Biomedical Sciences and Pharmacy, College of Health, Medicine and Wellbeing, The University of Newcastle, Callaghan, New South Wales 2308, Australia;Hunter Medical Research Institute, New Lambton Heights, New South Wales 2305, Australia;Hunter Hematology Research Group, Calvary Mater Newcastle Hospital, Waratah, New South Wales 2298, Australia
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29
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Krogsaeter E, Rosato AS, Grimm C. TRPMLs and TPCs: targets for lysosomal storage and neurodegenerative disease therapy? Cell Calcium 2022; 103:102553. [DOI: 10.1016/j.ceca.2022.102553] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 02/04/2022] [Accepted: 02/04/2022] [Indexed: 12/25/2022]
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30
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Sarnobat D, Moffett RC, Flatt PR, Tarasov AI. Effects of first-line diabetes therapy with biguanides, sulphonylurea and thiazolidinediones on the differentiation, proliferation and apoptosis of islet cell populations. J Endocrinol Invest 2022; 45:95-103. [PMID: 34191257 PMCID: PMC8741670 DOI: 10.1007/s40618-021-01620-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 06/17/2021] [Indexed: 12/13/2022]
Abstract
AIMS Metformin, rosiglitazone and sulfonylureas enhance either insulin action or secretion and thus have been used extensively as early stage anti-diabetic medication, independently of the aetiology of the disease. When administered to newly diagnosed diabetes patients, these drugs produce variable results. Here, we examined the effects of the three early stage oral hypoglycaemic agents in mice with diabetes induced by multiple low doses of streptozotocin, focusing specifically on the developmental biology of pancreatic islets. METHODS Streptozotocin-treated diabetic mice expressing a fluorescent reporter specifically in pancreatic islet α-cells were administered the biguanide metformin (100 mg/kg), thiazolidinedione rosiglitazone (10 mg/kg), or sulfonylurea tolbutamide (20 mg/kg) for 10 days. We assessed the impact of the treatment on metabolic status of the animals as well as on the morphology, proliferative potential and transdifferentiation of pancreatic islet cells, using immunofluorescence. RESULTS The effect of the therapy on the islet cells varied depending on the drug and included enhanced pancreatic islet β-cell proliferation, in case of metformin and rosiglitazone; de-differentiation of α-cells and β-cell apoptosis with tolbutamide; increased relative number of β-cells and bi-hormonal insulin + glucagon + cells with metformin. These effects were accompanied by normalisation of food and fluid intake with only minor effects on glycaemia at the low doses of the agents employed. CONCLUSIONS Our data suggest that metformin and rosiglitazone attenuate the depletion of the β-cell pool in the streptozotocin-induced diabetes, whereas tolbutamide exacerbates the β-cell apoptosis, but is likely to protect β-cells from chronic hyperglycaemia by directly elevating insulin secretion.
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Affiliation(s)
- D Sarnobat
- School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine, BT52 1SA, Northern Ireland, UK
| | - R C Moffett
- School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine, BT52 1SA, Northern Ireland, UK
| | - P R Flatt
- School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine, BT52 1SA, Northern Ireland, UK
| | - A I Tarasov
- School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine, BT52 1SA, Northern Ireland, UK.
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31
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Goldstein DS. Stress and the "extended" autonomic system. Auton Neurosci 2021; 236:102889. [PMID: 34656967 PMCID: PMC10699409 DOI: 10.1016/j.autneu.2021.102889] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2021] [Revised: 09/06/2021] [Accepted: 09/28/2021] [Indexed: 12/22/2022]
Abstract
This review updates three key concepts of autonomic neuroscience-stress, the autonomic nervous system (ANS), and homeostasis. Hans Selye popularized stress as a scientific idea. He defined stress variously as a stereotyped response pattern, a state that evokes this pattern, or a stimulus that evokes the state. According to the "homeostat" theory stress is a condition where a comparator senses a discrepancy between sensed afferent input and a response algorithm, the integrated error signal eliciting specific patterns of altered effector outflows. Scientific advances since Langley's definition of the ANS have incited the proposal here of the "extended autonomic system," or EAS, for three reasons. (1) Several neuroendocrine systems are bound inextricably to Langley's ANS. The first to be described, by Cannon in the early 1900s, involves the hormone adrenaline, the main effector chemical of the sympathetic adrenergic system. Other neuroendocrine systems are the hypothalamic-pituitary-adrenocortical system, the arginine vasopressin system, and the renin-angiotensin-aldosterone system. (2) An evolving body of research links the ANS complexly with inflammatory/immune systems, including vagal anti-inflammatory and catecholamine-related inflammasomal components. (3) A hierarchical network of brain centers (the central autonomic network, CAN) regulates ANS outflows. Embedded within the CAN is the central stress system conceptualized by Chrousos and Gold. According to the allostasis concept, homeostatic input-output curves can be altered in an anticipatory, feed-forward manner; and prolonged or inappropriate allostatic adjustments increase wear-and-tear (allostatic load), resulting in chronic, stress-related, multi-system disorders. This review concludes with sections on clinical and therapeutic implications of the updated concepts offered here.
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Affiliation(s)
- David S Goldstein
- Autonomic Medicine Section, Clinical Neurosciences Program, Division of Intramural Research, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA; Autonomic Medicine Section, CNP/DIR/NINDS/NIH, 9000 Rockville Pike MSC-1620, Building 10 Room 8N260, Bethesda, MD 20892-1620, USA..
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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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Abstract
This review focuses on the human pancreatic islet-including its structure, cell composition, development, function, and dysfunction. After providing a historical timeline of key discoveries about human islets over the past century, we describe new research approaches and technologies that are being used to study human islets and how these are providing insight into human islet physiology and pathophysiology. We also describe changes or adaptations in human islets in response to physiologic challenges such as pregnancy, aging, and insulin resistance and discuss islet changes in human diabetes of many forms. We outline current and future interventions being developed to protect, restore, or replace human islets. The review also highlights unresolved questions about human islets and proposes areas where additional research on human islets is needed.
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Affiliation(s)
- John T Walker
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Diane C Saunders
- Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Marcela Brissova
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Alvin C Powers
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
- Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- VA Tennessee Valley Healthcare System, Nashville, Tennessee, USA
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Martínez MS, Manzano A, Olivar LC, Nava M, Salazar J, D’Marco L, Ortiz R, Chacín M, Guerrero-Wyss M, Cabrera de Bravo M, Cano C, Bermúdez V, Angarita L. The Role of the α Cell in the Pathogenesis of Diabetes: A World beyond the Mirror. Int J Mol Sci 2021; 22:9504. [PMID: 34502413 PMCID: PMC8431704 DOI: 10.3390/ijms22179504] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 08/26/2021] [Accepted: 08/26/2021] [Indexed: 12/11/2022] Open
Abstract
Type 2 Diabetes Mellitus (T2DM) is one of the most prevalent chronic metabolic disorders, and insulin has been placed at the epicentre of its pathophysiological basis. However, the involvement of impaired alpha (α) cell function has been recognized as playing an essential role in several diseases, since hyperglucagonemia has been evidenced in both Type 1 and T2DM. This phenomenon has been attributed to intra-islet defects, like modifications in pancreatic α cell mass or dysfunction in glucagon's secretion. Emerging evidence has shown that chronic hyperglycaemia provokes changes in the Langerhans' islets cytoarchitecture, including α cell hyperplasia, pancreatic beta (β) cell dedifferentiation into glucagon-positive producing cells, and loss of paracrine and endocrine regulation due to β cell mass loss. Other abnormalities like α cell insulin resistance, sensor machinery dysfunction, or paradoxical ATP-sensitive potassium channels (KATP) opening have also been linked to glucagon hypersecretion. Recent clinical trials in phases 1 or 2 have shown new molecules with glucagon-antagonist properties with considerable effectiveness and acceptable safety profiles. Glucagon-like peptide-1 (GLP-1) agonists and Dipeptidyl Peptidase-4 inhibitors (DPP-4 inhibitors) have been shown to decrease glucagon secretion in T2DM, and their possible therapeutic role in T1DM means they are attractive as an insulin-adjuvant therapy.
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Affiliation(s)
- María Sofía Martínez
- MedStar Health Internal Medicine, Georgetown University Affiliated, Baltimore, MD 21218-2829, USA;
| | - Alexander Manzano
- Endocrine and Metabolic Diseases Research Center, School of Medicine, Universidad del Zulia, Maracaibo 4002, Venezuela; (A.M.); (L.C.O.); (M.N.); (J.S.); (C.C.)
| | - Luis Carlos Olivar
- Endocrine and Metabolic Diseases Research Center, School of Medicine, Universidad del Zulia, Maracaibo 4002, Venezuela; (A.M.); (L.C.O.); (M.N.); (J.S.); (C.C.)
| | - Manuel Nava
- Endocrine and Metabolic Diseases Research Center, School of Medicine, Universidad del Zulia, Maracaibo 4002, Venezuela; (A.M.); (L.C.O.); (M.N.); (J.S.); (C.C.)
| | - Juan Salazar
- Endocrine and Metabolic Diseases Research Center, School of Medicine, Universidad del Zulia, Maracaibo 4002, Venezuela; (A.M.); (L.C.O.); (M.N.); (J.S.); (C.C.)
| | - Luis D’Marco
- Department of Nephrology, Hospital Clinico Universitario de Valencia, INCLIVA, University of Valencia, 46010 Valencia, Spain;
| | - Rina Ortiz
- Facultad de Medicina, Universidad Católica de Cuenca, Ciudad de Cuenca, Azuay 010105, Ecuador;
| | - Maricarmen Chacín
- Facultad de Ciencias de la Salud, Universidad Simón Bolívar, Barranquilla 080022, Colombia; (M.C.); (V.B.)
| | - Marion Guerrero-Wyss
- Escuela de Nutrición y Dietética, Facultad de Ciencias Para el Cuidado de la Salud, Universidad San Sebastián, Valdivia 5090000, Chile;
| | | | - Clímaco Cano
- Endocrine and Metabolic Diseases Research Center, School of Medicine, Universidad del Zulia, Maracaibo 4002, Venezuela; (A.M.); (L.C.O.); (M.N.); (J.S.); (C.C.)
| | - Valmore Bermúdez
- Facultad de Ciencias de la Salud, Universidad Simón Bolívar, Barranquilla 080022, Colombia; (M.C.); (V.B.)
| | - Lisse Angarita
- Escuela de Nutrición y Dietética, Facultad de Medicina, Universidad Andres Bello, Sede Concepción 4260000, Chile
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Jin X, Zhang Y, Alharbi A, Hanbashi A, Alhoshani A, Parrington J. Targeting Two-Pore Channels: Current Progress and Future Challenges. Trends Pharmacol Sci 2021; 41:582-594. [PMID: 32679067 PMCID: PMC7365084 DOI: 10.1016/j.tips.2020.06.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 06/04/2020] [Accepted: 06/04/2020] [Indexed: 12/19/2022]
Abstract
Two-pore channels (TPCs) are cation-permeable channels located on endolysosomal membranes and important mediators of intracellular Ca2+ signalling. TPCs are involved in various pathophysiological processes, including cell growth and development, metabolism, and cancer progression. Most studies of TPCs have used TPC–/– cell or whole-animal models, or Ned-19, an indirect inhibitor. The TPC activation mechanism remains controversial, which has made it difficult to develop selective modulators. Recent studies of TPC structure and their interactomes are aiding the development of direct pharmacological modulators. This process is still in its infancy, but will facilitate future research and TPC targeting for therapeutical purposes. Here, we review the progress of current research into TPCs, including recent insights into their structures, functional roles, mechanisms of activation, and pharmacological modulators. Two-pore channel (TPC)-mediated endolysosomal Ca2+ signalling regulates a variety of processes, including cell proliferation, differentiation, metabolism, viral infection, and cardiac function. Despite the well-established model that TPCs are Ca2+-selective channels indirectly activated by nicotinic acid adenine dinucleotide phosphate (NAADP), it has also been proposed that TPCs as Na+ channels are activated directly by phosphatidylinositol 3,5-bisphosphate [PI(3,5)P2]. 3D structures of mouse TPC1 and human TPC2 were recently determined, which made it possible for structure-based virtual screening methods to identify pharmacological modulators of TPC. Recent identification by high-throughput screens of pharmacological modulators that target TPCs will help reveal the molecular mechanisms underlying the role of endolysosomal Ca2+ signalling in different pathophysiological processes, and to develop new therapeutics.
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Affiliation(s)
- Xuhui Jin
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT, UK
| | - Yuxuan Zhang
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT, UK
| | - Abeer Alharbi
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT, UK
| | - Ali Hanbashi
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT, UK
| | - Ali Alhoshani
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, PO Box 2457, Riyadh 11454, Kingdom of Saudi Arabia
| | - John Parrington
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT, UK.
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Abstract
Neurons are highly specialized cells equipped with a sophisticated molecular machinery for the reception, integration, conduction and distribution of information. The evolutionary origin of neurons remains unsolved. How did novel and pre-existing proteins assemble into the complex machinery of the synapse and of the apparatus conducting current along the neuron? In this review, the step-wise assembly of functional modules in neuron evolution serves as a paradigm for the emergence and modification of molecular machinery in the evolution of cell types in multicellular organisms. The pre-synaptic machinery emerged through modification of calcium-regulated large vesicle release, while the postsynaptic machinery has different origins: the glutamatergic postsynapse originated through the fusion of a sensory signaling module and a module for filopodial outgrowth, while the GABAergic postsynapse incorporated an ancient actin regulatory module. The synaptic junction, in turn, is built around two adhesion modules controlled by phosphorylation, which resemble septate and adherens junctions. Finally, neuronal action potentials emerged via a series of duplications and modifications of voltage-gated ion channels. Based on these origins, key molecular innovations are identified that led to the birth of the first neuron in animal evolution.
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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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Noueiri B, Nassif N. Dental Treatment Effect on Blood Glucose Level Fluctuation in Type 1 Unbalanced Diabetic Children. Int J Clin Pediatr Dent 2021; 14:497-501. [PMID: 34824503 PMCID: PMC8585890 DOI: 10.5005/jp-journals-10005-1985] [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] [Indexed: 11/23/2022] Open
Abstract
Diabetic patients struggle to maintain their blood glucose near normal levels to avoid the occurrence of hypo- or hyperglycemia discomfort. Dental practitioners must foresee such complications as they can also take place during dental treatment. AIM AND OBJECTIVE This study aims to evaluate the impact of the type and duration of dental treatment on the blood glucose level (BGL) fluctuation in type 1 unbalanced diabetic children [hemoglobin A1c (HbA1c) >7]. MATERIAL AND METHODS A cross-sectional approach was conducted on 83 type 1 unbalanced diabetic children (HbA1c) > 7%, aged between 7 years and 12 years, divided into 40 females and 43 males in the Department of Pediatric Dentistry at the Lebanese University in Beirut. For dental treatments, diabetic children were scheduled for morning sessions 60-90 minutes after breakfast intake and a habitual insulin shot. Only patients with a BGL between 70 mg/dL and 300 mg/dL underwent dental treatments. The type, the duration of the dental session, and the BGL at the baseline (T0), and at the end of the session (T1) were recorded. The dental acts were classified into simple (without local anesthesia) and unpleasant with a solution of 2% lignocaine with 1:200,000 epinephrine. Statistical analyses were performed. RESULTS Fifty of 83 showed a decrease in their BGLs after dental treatments, 20 an increase, and 13 no change. For both genders, in simple acts, a statistical significance was noted (p = 0.0002) for the female and (p = 0.0014) for the males. CONCLUSION Treatment unbalanced diabetic children can be safely done by taking some precautions and measures to avoid a hypo- or hyperglycemia episode. HOW TO CITE THIS ARTICLE Noueiri B, Nassif N. Dental Treatment Effect on Blood Glucose Level Fluctuation in Type 1 Unbalanced Diabetic Children. Int J Clin Pediatr Dent 2021;14(4):497-501.
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Affiliation(s)
- Balsam Noueiri
- Department of Pediatric Dentistry, Lebanese University, Beirut, Lebanon
| | - Nahla Nassif
- Department of Pediatric Dentistry, Lebanese University, Beirut, Lebanon
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Singh B, Khattab F, Chae H, Desmet L, Herrera PL, Gilon P. K ATP channel blockers control glucagon secretion by distinct mechanisms: A direct stimulation of α-cells involving a [Ca 2+] c rise and an indirect inhibition mediated by somatostatin. Mol Metab 2021; 53:101268. [PMID: 34118477 PMCID: PMC8274344 DOI: 10.1016/j.molmet.2021.101268] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 05/10/2021] [Accepted: 06/03/2021] [Indexed: 02/06/2023] Open
Abstract
Objective Glucagon is secreted by pancreatic α-cells in response to hypoglycemia and its hyperglycemic effect helps to restore normal blood glucose. Insulin and somatostatin (SST) secretions from β- and δ-cells, respectively, are stimulated by glucose by mechanisms involving an inhibition of their ATP-sensitive K+ (KATP) channels, leading to an increase in [Ca2+]c that triggers exocytosis. Drugs that close KATP channels, such as sulfonylureas, are used to stimulate insulin release in type 2 diabetic patients. α-cells also express KATP channels. However, the mechanisms by which sulfonylureas control glucagon secretion are still largely debated and were addressed in the present study. In particular, we studied the effects of KATP channel blockers on α-cell [Ca2+]c and glucagon secretion in the presence of a low (1 mM) or a high (15 mM) glucose concentration and evaluated the role of SST in these effects. Methods Using a transgenic mouse model expressing the Ca2+-sensitive fluorescent protein, GCaMP6f, specifically in α-cells, we measured [Ca2+]c in α-cells either dispersed or within whole islets (by confocal microscopy). By measuring [Ca2+]c in α-cells within islets and glucagon secretion using the same perifusion protocols, we tested whether glucagon secretion correlated with changes in [Ca2+]c in response to sulfonylureas. We studied the role of SST in the effects of sulfonylureas using multiple approaches including genetic ablation of SST, or application of SST-14 and SST receptor antagonists. Results Application of the sulfonylureas, tolbutamide, or gliclazide, to a medium containing 1 mM or 15 mM glucose increased [Ca2+]c in α-cells by a direct effect as in β-cells. At low glucose, sulfonylureas inhibited glucagon secretion of islets despite the rise in α-cell [Ca2+]c that they triggered. This glucagonostatic effect was indirect and attributed to SST because, in the islets of SST-knockout mice, sulfonylureas induced a stimulation of glucagon secretion which correlated with an increase in α-cell [Ca2+]c. Experiments with exogenous SST-14 and SST receptor antagonists indicated that the glucagonostatic effect of sulfonylureas mainly resulted from an inhibition of the efficacy of cytosolic Ca2+ on exocytosis. Although SST-14 was also able to inhibit glucagon secretion by decreasing α-cell [Ca2+]c, no decrease in [Ca2+]c occurred during sulfonylurea application because it was largely counterbalanced by the direct stimulatory effect of these drugs on α-cell [Ca2+]c. At high glucose, i.e., in conditions where glucagon release was already low, sulfonylureas stimulated glucagon secretion because their direct stimulatory effect on α-cells exceeded the indirect effect by SST. Our results also indicated that, unexpectedly, SST-14 poorly decreased the efficacy of Ca2+ on exocytosis in β-cells. Conclusions Sulfonylureas exert two opposite actions on α-cells: a direct stimulation as in β-cells and an indirect inhibition by SST. This suggests that any alteration of SST paracrine influence, as described in diabetes, will modify the effect of sulfonylureas on glucagon release. In addition, we suggest that δ-cells inhibit α-cells more efficiently than β-cells. KATP channel blockers control glucagon secretion by two mechanisms. The first one is the direct stimulation of α-cell by a [Ca2+]c rise, as in β-cells. The second one is an indirect inhibition mediated by δ-cells releasing somatostatin. Somatostatin mainly reduces the efficacy of Ca2+ on exocytosis in α-cells. Somatostatin more potently inhibits glucagon than insulin secretion.
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Affiliation(s)
- Bilal Singh
- Université Catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle d'Endocrinologie, Diabète et Nutrition, Brussels, Belgium
| | - Firas Khattab
- Université Catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle d'Endocrinologie, Diabète et Nutrition, Brussels, Belgium
| | - Heeyoung Chae
- Université Catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle d'Endocrinologie, Diabète et Nutrition, Brussels, Belgium
| | - Lieven Desmet
- Université Catholique de Louvain, SMCS, Louvain Institute of Data Analysis and Modeling in economics and statistics, Louvain-la-Neuve, Belgium
| | - Pedro L Herrera
- Department of Genetic Medicine and Development, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Patrick Gilon
- Université Catholique de Louvain, Institut de Recherche Expérimentale et Clinique, Pôle d'Endocrinologie, Diabète et Nutrition, Brussels, Belgium.
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Davis MA, Camacho LE, Pendleton AL, Antolic AT, Luna-Ramirez RI, Kelly AC, Steffens NR, Anderson MJ, Limesand SW. Augmented glucose production is not contingent on high catecholamines in fetal sheep with IUGR. J Endocrinol 2021; 249:195-207. [PMID: 33994373 PMCID: PMC8175032 DOI: 10.1530/joe-21-0071] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 04/22/2021] [Indexed: 01/04/2023]
Abstract
Fetuses with intrauterine growth restriction (IUGR) have high concentrations of catecholamines, which lowers the insulin secretion and glucose uptake. Here, we studied the effect of hypercatecholaminemia on glucose metabolism in sheep fetuses with placental insufficiency-induced IUGR. Norepinephrine concentrations are elevated throughout late gestation in IUGR fetuses but not in IUGR fetuses with a bilateral adrenal demedullation (IAD) at 0.65 of gestation. Euglycemic (EC) and hyperinsulinemic-euglycemic (HEC) clamps were performed in control, intact-IUGR, and IAD fetuses at 0.87 of gestation. Compared to controls, basal oxygen, glucose, and insulin concentrations were lower in IUGR groups. Norepinephrine concentrations were five-fold higher in IUGR fetuses than in IAD fetuses. During the EC, rates of glucose entry (GER, umbilical + exogenous), glucose utilization (GUR), and glucose oxidation (GOR) were greater in IUGR groups than in controls. In IUGR and IAD fetuses with euglycemia and euinsulinemia, glucose production rates (GPR) remained elevated. During the HEC, GER and GOR were not different among groups. In IUGR and IAD fetuses, GURs were 40% greater than in controls, which paralleled the sustained GPR despite hyperinsulinemia. Glucose-stimulated insulin concentrations were augmented in IAD fetuses compared to IUGR fetuses. Fetal weights were not different between IUGR groups but were less than controls. Regardless of norepinephrine concentrations, IUGR fetuses not only develop greater peripheral insulin sensitivity for glucose utilization but also develop hepatic insulin resistance because GPR was maintained and unaffected by euglycemia or hyperinsulinemia. These findings show that adaptation in glucose metabolism of IUGR fetuses are independent of catecholamines, which implicate that hypoxemia and hypoglycemia cause the metabolic responses.
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Affiliation(s)
- Melissa A Davis
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona, USA
| | - Leticia E Camacho
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona, USA
| | - Alexander L Pendleton
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona, USA
| | - Andrew T Antolic
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona, USA
| | - Rosa I Luna-Ramirez
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona, USA
| | - Amy C Kelly
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona, USA
| | - Nathan R Steffens
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona, USA
| | - Miranda J Anderson
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona, USA
| | - Sean W Limesand
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona, USA
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Campbell-Thompson M, Butterworth EA, Boatwright JL, Nair MA, Nasif LH, Nasif K, Revell AY, Riva A, Mathews CE, Gerling IC, Schatz DA, Atkinson MA. Islet sympathetic innervation and islet neuropathology in patients with type 1 diabetes. Sci Rep 2021; 11:6562. [PMID: 33753784 PMCID: PMC7985489 DOI: 10.1038/s41598-021-85659-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 03/04/2021] [Indexed: 02/07/2023] Open
Abstract
Dysregulation of glucagon secretion in type 1 diabetes (T1D) involves hypersecretion during postprandial states, but insufficient secretion during hypoglycemia. The sympathetic nervous system regulates glucagon secretion. To investigate islet sympathetic innervation in T1D, sympathetic tyrosine hydroxylase (TH) axons were analyzed in control non-diabetic organ donors, non-diabetic islet autoantibody-positive individuals (AAb), and age-matched persons with T1D. Islet TH axon numbers and density were significantly decreased in AAb compared to T1D with no significant differences observed in exocrine TH axon volume or lengths between groups. TH axons were in close approximation to islet α-cells in T1D individuals with long-standing diabetes. Islet RNA-sequencing and qRT-PCR analyses identified significant alterations in noradrenalin degradation, α-adrenergic signaling, cardiac β-adrenergic signaling, catecholamine biosynthesis, and additional neuropathology pathways. The close approximation of TH axons at islet α-cells supports a model for sympathetic efferent neurons directly regulating glucagon secretion. Sympathetic islet innervation and intrinsic adrenergic signaling pathways could be novel targets for improving glucagon secretion in T1D.
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Affiliation(s)
- Martha Campbell-Thompson
- Department of Pathology, Immunology, and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL, 32610, USA. .,Department of Biomedical Engineering, College of Engineering, University of Florida, Gainesville, FL, 32610, USA.
| | - Elizabeth A Butterworth
- Department of Pathology, Immunology, and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL, 32610, USA
| | - J Lucas Boatwright
- Bioinformatics Core, Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL, 32610, USA
| | - Malavika A Nair
- Department of Pathology, Immunology, and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL, 32610, USA
| | - Lith H Nasif
- Department of Pathology, Immunology, and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL, 32610, USA
| | - Kamal Nasif
- Department of Pathology, Immunology, and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL, 32610, USA
| | - Andy Y Revell
- Department of Pathology, Immunology, and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL, 32610, USA
| | - Alberto Riva
- Bioinformatics Core, Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL, 32610, USA
| | - Clayton E Mathews
- Department of Pathology, Immunology, and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL, 32610, USA
| | - Ivan C Gerling
- Department of Medicine-Endocrinology, University of Tennessee Health Science Center, Memphis, TN, 38163, USA
| | - Desmond A Schatz
- Department of Pediatrics, College of Medicine, University of Florida, Gainesville, FL, 32610, USA
| | - Mark A Atkinson
- Department of Pathology, Immunology, and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL, 32610, USA.,Department of Pediatrics, College of Medicine, University of Florida, Gainesville, FL, 32610, USA
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42
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Revealing lipid droplets evolution at nanoscale under proteohormone stimulation by a BODIPY- hexylcarbazole derivative. Biosens Bioelectron 2021; 175:112871. [DOI: 10.1016/j.bios.2020.112871] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 11/19/2020] [Accepted: 11/26/2020] [Indexed: 12/15/2022]
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43
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Oduori OS, Murao N, Shimomura K, Takahashi H, Zhang Q, Dou H, Sakai S, Minami K, Chanclon B, Guida C, Kothegala L, Tolö J, Maejima Y, Yokoi N, Minami Y, Miki T, Rorsman P, Seino S. Gs/Gq signaling switch in β cells defines incretin effectiveness in diabetes. J Clin Invest 2021; 130:6639-6655. [PMID: 33196462 DOI: 10.1172/jci140046] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 09/03/2020] [Indexed: 12/15/2022] Open
Abstract
By restoring glucose-regulated insulin secretion, glucagon-like peptide-1-based (GLP-1-based) therapies are becoming increasingly important in diabetes care. Normally, the incretins GLP-1 and glucose-dependent insulinotropic polypeptide (GIP) jointly maintain normal blood glucose levels by stimulation of insulin secretion in pancreatic β cells. However, the reason why only GLP-1-based drugs are effective in improving insulin secretion after presentation of diabetes has not been resolved. ATP-sensitive K+ (KATP) channels play a crucial role in coupling the systemic metabolic status to β cell electrical activity for insulin secretion. Here, we have shown that persistent membrane depolarization of β cells due to genetic (β cell-specific Kcnj11-/- mice) or pharmacological (long-term exposure to sulfonylureas) inhibition of the KATP channel led to a switch from Gs to Gq in a major amplifying pathway of insulin secretion. The switch determined the relative insulinotropic effectiveness of GLP-1 and GIP, as GLP-1 can activate both Gq and Gs, while GIP only activates Gs. The findings were corroborated in other models of persistent depolarization: a spontaneous diabetic KK-Ay mouse and nondiabetic human and mouse β cells of pancreatic islets chronically treated with high glucose. Thus, a Gs/Gq signaling switch in β cells exposed to chronic hyperglycemia underlies the differential insulinotropic potential of incretins in diabetes.
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Affiliation(s)
- Okechi S Oduori
- Division of Molecular and Metabolic Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Naoya Murao
- Division of Molecular and Metabolic Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Kenju Shimomura
- Department of Bioregulation and Pharmacological Medicine, Fukushima Medical University School of Medicine, Fukushima, Japan
| | - Harumi Takahashi
- Division of Molecular and Metabolic Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Quan Zhang
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Haiqiang Dou
- Metabolic Research Unit, Institute of Neuroscience and Physiology, University of Gothenburg, Gothenburg, Sweden
| | - Shihomi Sakai
- Division of Molecular and Metabolic Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Kohtaro Minami
- Division of Molecular and Metabolic Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Belen Chanclon
- Metabolic Research Unit, Institute of Neuroscience and Physiology, University of Gothenburg, Gothenburg, Sweden
| | - Claudia Guida
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Lakshmi Kothegala
- Metabolic Research Unit, Institute of Neuroscience and Physiology, University of Gothenburg, Gothenburg, Sweden
| | - Johan Tolö
- Metabolic Research Unit, Institute of Neuroscience and Physiology, University of Gothenburg, Gothenburg, Sweden
| | - Yuko Maejima
- Department of Bioregulation and Pharmacological Medicine, Fukushima Medical University School of Medicine, Fukushima, Japan
| | - Norihide Yokoi
- Division of Molecular and Metabolic Medicine, Kobe University Graduate School of Medicine, Kobe, Japan.,Laboratory of Animal Breeding and Genetics, Division of Applied Biosciences, Kyoto University Graduate School of Agriculture, Kyoto, Japan
| | - Yasuhiro Minami
- Division of Cell Physiology, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Takashi Miki
- Division of Molecular and Metabolic Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom.,Metabolic Research Unit, Institute of Neuroscience and Physiology, University of Gothenburg, Gothenburg, Sweden
| | - Susumu Seino
- Division of Molecular and Metabolic Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
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44
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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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45
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Böck J, Krogsaeter E, Passon M, Chao YK, Sharma S, Grallert H, Peters A, Grimm C. Human genome diversity data reveal that L564P is the predominant TPC2 variant and a prerequisite for the blond hair associated M484L gain-of-function effect. PLoS Genet 2021; 17:e1009236. [PMID: 33465068 PMCID: PMC7845996 DOI: 10.1371/journal.pgen.1009236] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 01/29/2021] [Accepted: 10/29/2020] [Indexed: 12/29/2022] Open
Abstract
The endo-lysosomal two-pore channel (TPC2) has been established as an intracellular cation channel of significant physiological and pathophysiological relevance in recent years. For example, TPC2-/- mice show defects in cholesterol degradation, leading to hypercholesterinemia; TPC2 absence also results in mature-onset obesity, and a role in glucagon secretion and diabetes has been proposed. Infections with bacterial toxins or viruses e.g., cholera toxin or Ebola virus result in reduced infectivity rates in the absence of TPC2 or after pharmacological blockage, and TPC2-/- cancer cells lose their ability to migrate and metastasize efficiently. Finally, melanin production is affected by changes in hTPC2 activity, resulting in pigmentation defects and hair color variation. Here, we analyzed several publicly available genome variation data sets and identified multiple variations in the TPC2 protein in distinct human populations. Surprisingly, one variation, L564P, was found to be the predominant TPC2 isoform on a global scale. By applying endo-lysosomal patch-clamp electrophysiology, we found that L564P is a prerequisite for the previously described M484L gain-of-function effect that is associated with blond hair. Additionally, other gain-of-function variants with distinct geographical and ethnic distribution were discovered and functionally characterized. A meta-analysis of genome-wide association studies was performed, finding the polymorphisms to be associated with both distinct and overlapping traits. In sum, we present the first systematic analysis of variations in TPC2. We functionally characterized the most common variations and assessed their association with various disease traits. With TPC2 emerging as a novel drug target for the treatment of various diseases, this study provides valuable insights into ethnic and geographical distribution of TPC2 polymorphisms and their effects on channel activity.
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Affiliation(s)
- Julia Böck
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians-Universität, Munich, Germany
| | - Einar Krogsaeter
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians-Universität, Munich, Germany
| | - Marcel Passon
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians-Universität, Munich, Germany
| | - Yu-Kai Chao
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians-Universität, Munich, Germany
| | - Sapna Sharma
- Helmholtz Zentrum–Deutsches Forschungszentrum für Gesundheit und Umwelt (GmbH), Institute of Epidemiology, Neuherberg, Germany
| | - Harald Grallert
- Helmholtz Zentrum–Deutsches Forschungszentrum für Gesundheit und Umwelt (GmbH), Institute of Epidemiology, Neuherberg, Germany
| | - Annette Peters
- Helmholtz Zentrum–Deutsches Forschungszentrum für Gesundheit und Umwelt (GmbH), Institute of Epidemiology, Neuherberg, Germany
| | - Christian Grimm
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians-Universität, Munich, Germany
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46
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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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47
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Two-pore and TRPML cation channels: Regulators of phagocytosis, autophagy and lysosomal exocytosis. Pharmacol Ther 2020; 220:107713. [PMID: 33141027 DOI: 10.1016/j.pharmthera.2020.107713] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 10/19/2020] [Indexed: 02/07/2023]
Abstract
The old Greek saying "Panta Rhei" ("everything flows") is true for all life and all living things in general. It also becomes nicely evident when looking closely into cells. There, material from the extracellular space is taken up by endocytic processes and transported to endosomes where it is sorted either for recycling or degradation. Cargo is also packaged for export through exocytosis involving the Golgi network, lysosomes and other organelles. Everything in this system is in constant motion and many proteins are necessary to coordinate transport along the different intracellular pathways to avoid chaos. Among these proteins are ion channels., in particular TRPML channels (mucolipins) and two-pore channels (TPCs) which reside on endosomal and lysosomal membranes to speed up movement between organelles, e.g. by regulating fusion and fission; they help readjust pH and osmolarity changes due to such processes, or they promote exocytosis of export material. Pathophysiologically, these channels are involved in neurodegenerative, metabolic, retinal and infectious diseases, cancer, pigmentation defects, and immune cell function, and thus have been proposed as novel pharmacological targets, e.g. for the treatment of lysosomal storage disorders, Duchenne muscular dystrophy, or different types of cancer. Here, we discuss the similarities but also differences of TPCs and TRPMLs in regulating phagocytosis, autophagy and lysosomal exocytosis, and we address the contradictions and open questions in the field relating to the roles TPCs and TRPMLs play in these different processes.
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48
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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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49
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Abstract
The pandemic viral illness COVID-19 is especially life-threatening in the elderly and in those with any of a variety of chronic medical conditions. This essay explores the possibility that the heightened risk may involve activation of the "extended autonomic system" (EAS). Traditionally, the autonomic nervous system has been viewed as consisting of the sympathetic nervous system, the parasympathetic nervous system, and the enteric nervous system. Over the past century, however, neuroendocrine and neuroimmune systems have come to the fore, justifying expansion of the meaning of "autonomic." Additional facets include the sympathetic adrenergic system, for which adrenaline is the key effector; the hypothalamic-pituitary-adrenocortical axis; arginine vasopressin (synonymous with anti-diuretic hormone); the renin-angiotensin-aldosterone system, with angiotensin II and aldosterone the main effectors; and cholinergic anti-inflammatory and sympathetic inflammasomal pathways. A hierarchical brain network-the "central autonomic network"-regulates these systems; embedded within it are components of the Chrousos/Gold "stress system." Acute, coordinated alterations in homeostatic settings (allostasis) can be crucial for surviving stressors such as traumatic hemorrhage, asphyxiation, and sepsis, which throughout human evolution have threatened homeostasis; however, intense or long-term EAS activation may cause harm. While required for appropriate responses in emergencies, EAS activation in the setting of chronically decreased homeostatic efficiencies (dyshomeostasis) may reduce thresholds for induction of destabilizing, lethal vicious cycles. Testable hypotheses derived from these concepts are that biomarkers of EAS activation correlate with clinical and pathophysiologic data and predict outcome in COVID-19 and that treatments targeting specific abnormalities identified in individual patients may be beneficial.
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Affiliation(s)
- David S Goldstein
- Autonomic Medicine Section, Clinical Neurosciences Program, Division of Intramural Research, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 9000 Rockville Pike MSC-1620, Building 10 Room 8N260, Bethesda, MD, 20892-1620, USA.
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50
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Zaborska KE, Dadi PK, Dickerson MT, Nakhe AY, Thorson AS, Schaub CM, Graff SM, Stanley JE, Kondapavuluru RS, Denton JS, Jacobson DA. Lactate activation of α-cell K ATP channels inhibits glucagon secretion by hyperpolarizing the membrane potential and reducing Ca 2+ entry. Mol Metab 2020; 42:101056. [PMID: 32736089 PMCID: PMC7479281 DOI: 10.1016/j.molmet.2020.101056] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 07/17/2020] [Accepted: 07/24/2020] [Indexed: 12/20/2022] Open
Abstract
Objective Elevations in pancreatic α-cell intracellular Ca2+ ([Ca2+]i) lead to glucagon (GCG) secretion. Although glucose inhibits GCG secretion, how lactate and pyruvate control α-cell Ca2+ handling is unknown. Lactate enters cells through monocarboxylate transporters (MCTs) and is also produced during glycolysis by lactate dehydrogenase A (LDHA), an enzyme expressed in α-cells. As lactate activates ATP-sensitive K+ (KATP) channels in cardiomyocytes, lactate may also modulate α-cell KATP. Therefore, this study investigated how lactate signaling controls α-cell Ca2+ handling and GCG secretion. Methods Mouse and human islets were used in combination with confocal microscopy, electrophysiology, GCG immunoassays, and fluorescent thallium flux assays to assess α-cell Ca2+ handling, Vm, KATP currents, and GCG secretion. Results Lactate-inhibited mouse (75 ± 25%) and human (47 ± 9%) α-cell [Ca2+]i fluctuations only under low-glucose conditions (1 mM) but had no effect on β- or δ-cells [Ca2+]i. Glyburide inhibition of KATP channels restored α-cell [Ca2+]i fluctuations in the presence of lactate. Lactate transport into α-cells via MCTs hyperpolarized mouse (14 ± 1 mV) and human (12 ± 1 mV) α-cell Vm and activated KATP channels. Interestingly, pyruvate showed a similar KATP activation profile and α-cell [Ca2+]i inhibition as lactate. Lactate-induced inhibition of α-cell [Ca2+]i influx resulted in reduced GCG secretion in mouse (62 ± 6%) and human (43 ± 13%) islets. Conclusions These data demonstrate for the first time that lactate entry into α-cells through MCTs results in KATP activation, Vm hyperpolarization, reduced [Ca2+]i, and inhibition of GCG secretion. Thus, taken together, these data indicate that lactate either within α-cells and/or elevated in serum could serve as important modulators of α-cell function. Lactate reduces islet α-cell Ca2+ entry under low glucose conditions. Lactate does not alter β- or δ-cell Ca2+ handling under low glucose conditions. Lactate enters islet α-cells through monocarboxylate transporters. Lactate hyperpolarizes islet α-cell membrane potential by activating KATP channels. Lactate reduces mouse and human islet glucagon secretion.
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Affiliation(s)
- Karolina E Zaborska
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Prasanna K Dadi
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Matthew T Dickerson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Arya Y Nakhe
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Ariel S Thorson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Charles M Schaub
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Sarah M Graff
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Jade E Stanley
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Roy S Kondapavuluru
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Jerod S Denton
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA
| | - David A Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA.
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