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Welsh N. Are off-target effects of imatinib the key to improving beta-cell function in diabetes? Ups J Med Sci 2022; 127:8841. [PMID: 36187072 PMCID: PMC9487420 DOI: 10.48101/ujms.v127.8841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 07/18/2022] [Accepted: 07/27/2022] [Indexed: 11/18/2022] Open
Abstract
The small tyrosine kinase (TK) inhibitor imatinib mesylate (Gleevec, STI571) protects against both type 1 and type 2 diabetes, but as it inhibits many TKs and other proteins, it is not clear by which mechanisms it acts. This present review will focus on the possibility that imatinib acts, at least in part, by improving beta-cell function and survival via off-target effects on beta-cell signaling/metabolic flow events. Particular attention will be given to the possibility that imatinib and other TK inhibitors function as inhibitors of mitochondrial respiration. A better understanding of how imatinib counteracts diabetes will possibly help to clarify the pathogenic role of beta-cell signaling events and mitochondrial function, and hopefully leading to improved treatment of the disease.
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Affiliation(s)
- Nils Welsh
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
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Elksnis A, Schiffer TA, Palm F, Wang Y, Cen J, Turpaev K, Ngamjariyawat A, Younis S, Huang S, Shen Y, Leng Y, Bergsten P, Karlsborn T, Welsh N, Wang X. Imatinib protects against human beta-cell death via inhibition of mitochondrial respiration and activation of AMPK. Clin Sci (Lond) 2021; 135:2243-2263. [PMID: 34569605 DOI: 10.1042/cs20210604] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 09/22/2021] [Accepted: 09/27/2021] [Indexed: 12/17/2022]
Abstract
The protein tyrosine kinase inhibitor imatinib is used in the treatment of various malignancies but may also promote beneficial effects in the treatment of diabetes. The aim of the present investigation was to characterize the mechanisms by which imatinib protects insulin producing cells. Treatment of non-obese diabetic (NOD) mice with imatinib resulted in increased beta-cell AMP-activated kinase (AMPK) phosphorylation. Imatinib activated AMPK also in vitro, resulting in decreased ribosomal protein S6 phosphorylation and protection against islet amyloid polypeptide (IAPP)-aggregation, thioredoxin interacting protein (TXNIP) up-regulation and beta-cell death. 5-Aminoimidazole-4-carboxamide ribonucleotide (AICAR) mimicked and compound C counteracted the effect of imatinib on beta-cell survival. Imatinib-induced AMPK activation was preceded by reduced glucose/pyruvate-dependent respiration, increased glycolysis rates, and a lowered ATP/AMP ratio. Imatinib augmented the fractional oxidation of fatty acids/malate, possibly via a direct interaction with the beta-oxidation enzyme enoyl coenzyme A hydratase, short chain, 1, mitochondrial (ECHS1). In non-beta cells, imatinib reduced respiratory chain complex I and II-mediated respiration and acyl-CoA carboxylase (ACC) phosphorylation, suggesting that mitochondrial effects of imatinib are not beta-cell specific. In conclusion, tyrosine kinase inhibitors modestly inhibit mitochondrial respiration, leading to AMPK activation and TXNIP down-regulation, which in turn protects against beta-cell death.
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Affiliation(s)
- Andris Elksnis
- Science for Life Laboratory, Department of Medical Cell Biology, Uppsala University, Box 571, SE-751 23 Uppsala, Sweden
| | - Tomas A Schiffer
- Science for Life Laboratory, Department of Medical Cell Biology, Uppsala University, Box 571, SE-751 23 Uppsala, Sweden
| | - Fredrik Palm
- Science for Life Laboratory, Department of Medical Cell Biology, Uppsala University, Box 571, SE-751 23 Uppsala, Sweden
| | - Yun Wang
- Science for Life Laboratory, Department of Medical Cell Biology, Uppsala University, Box 571, SE-751 23 Uppsala, Sweden
| | - Jing Cen
- Science for Life Laboratory, Department of Medical Cell Biology, Uppsala University, Box 571, SE-751 23 Uppsala, Sweden
| | - Kyril Turpaev
- Science for Life Laboratory, Department of Medical Cell Biology, Uppsala University, Box 571, SE-751 23 Uppsala, Sweden
- Center for Theoretical Problems of Physicochemical Pharmacology, Russian Academy of Sciences, Moscow, Russia
| | - Anongnad Ngamjariyawat
- Science for Life Laboratory, Department of Medical Cell Biology, Uppsala University, Box 571, SE-751 23 Uppsala, Sweden
| | - Shady Younis
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
- Division of Immunology and Rheumatology, Stanford University, Stanford, CA, U.S.A
| | - Suling Huang
- State key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Science, Shanghai, China
| | - Yu Shen
- State key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Science, Shanghai, China
| | - Ying Leng
- State key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Science, Shanghai, China
| | - Peter Bergsten
- Science for Life Laboratory, Department of Medical Cell Biology, Uppsala University, Box 571, SE-751 23 Uppsala, Sweden
| | - Tony Karlsborn
- Swedish Metabolomics Centre, KBC Byggnaden, Plan 3, Linnaeus väg 6, 901 87 Umeå, Sweden
| | - Nils Welsh
- Science for Life Laboratory, Department of Medical Cell Biology, Uppsala University, Box 571, SE-751 23 Uppsala, Sweden
| | - Xuan Wang
- Science for Life Laboratory, Department of Medical Cell Biology, Uppsala University, Box 571, SE-751 23 Uppsala, Sweden
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Chen HY, Chiang YF, Wang KL, Huang TC, Ali M, Shieh TM, Chang HY, Hong YH, Hsia SM. Rice Husk Silica Liquid Protects Pancreatic β Cells from Streptozotocin-Induced Oxidative Damage. Antioxidants (Basel) 2021; 10:antiox10071080. [PMID: 34356312 PMCID: PMC8301121 DOI: 10.3390/antiox10071080] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 06/29/2021] [Accepted: 07/01/2021] [Indexed: 01/04/2023] Open
Abstract
Type 2 diabetes mellitus is a complex multifactorial disease characterized by insulin resistance and dysfunction of pancreatic β-cells. Rice husk silica liquid (RHSL) is derived from rice husks and has not been explored in diabetes mellitus until now. Previous studies showed that rice husk is enriched with silica, and its silica nanoparticles are higher more biocompatible. To investigate the potential protective role of RHSL on pancreatic β cells, we utilized RIN-m5F pancreatic β cells and explored RHSL effect after streptozotocin (STZ)-stimulation. The recovery effects of RHSL were evaluated using flow cytometry, Western blotting, and immunofluorescence analysis. Results of our study showed that RHSL reversed the cell viability, insulin secretion, reactive oxygen species (ROS) production, and the change of mitochondria membrane potential (ΔΨm) in STZ-treated RIN-m5F cells. Moreover, the expression of phospho-receptor-interacting protein 3 (p-RIP3) and cleaved-poly (ADP-ribose) polymerase (PARP), phospho-mammalian target of rapamycin (p-mTOR), and sequestosome-1 (p62/SQSTM1) were significantly decreased, while the transition of light chain (LC)3-I to LC3-II was markedly increased after RHSL treatment in STZ-induced RIN-m5F cells. Interestingly, using autophagy inhibitors such as 3-methyladenine (3-MA) and chloroquine (CQ) both showed an increase in cleaved-PARP protein level, indicating apoptosis induction. Taken together, this study demonstrated that RHSL induced autophagy and alleviated STZ-induced ROS-mediated apoptosis in RIN-m5F cells.
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Affiliation(s)
- Hsin-Yuan Chen
- School of Nutrition and Health Sciences, College of Nutrition, Taipei Medical University, Taipei 11031, Taiwan; (H.-Y.C.); (Y.-F.C.)
- Department of Nutrition, I-Shou University, Kaohsiung 84001, Taiwan
| | - Yi-Fen Chiang
- School of Nutrition and Health Sciences, College of Nutrition, Taipei Medical University, Taipei 11031, Taiwan; (H.-Y.C.); (Y.-F.C.)
| | - Kai-Lee Wang
- Department of Nursing, Ching Kuo Institute of Management and Health, Keelung 20301, Taiwan;
| | - Tsui-Chin Huang
- Graduate Institute of Cancer Biology and Drug Discovery, College of Medical Science and Technology, Taipei Medical University, Taipei 11031, Taiwan;
| | - Mohamed Ali
- Clinical Pharmacy Department, Faculty of Pharmacy, Ain Shams University, Cairo 11566, Egypt;
| | - Tzong-Ming Shieh
- School of Dentistry, College of Dentistry, China Medical University, Taichung 40402, Taiwan;
| | - Hsin-Yi Chang
- Graduate Institute of Metabolism and Obesity Sciences, College of Nutrition, Taipei Medical University, Taipei 11031, Taiwan;
| | - Yong-Han Hong
- Department of Nutrition, I-Shou University, Kaohsiung 84001, Taiwan
- Correspondence: (Y.-H.H.); (S.-M.H.); Tel.: +886-7-6151100 (ext. 7914) (Y.-H.H.); +886-2-27361661 (ext. 6558) (S.-M.H.)
| | - Shih-Min Hsia
- School of Nutrition and Health Sciences, College of Nutrition, Taipei Medical University, Taipei 11031, Taiwan; (H.-Y.C.); (Y.-F.C.)
- Graduate Institute of Metabolism and Obesity Sciences, College of Nutrition, Taipei Medical University, Taipei 11031, Taiwan;
- School of Food and Safety, Taipei Medical University, Taipei 11031, Taiwan
- Nutrition Research Center, Taipei Medical University Hospital, Taipei 11031, Taiwan
- Correspondence: (Y.-H.H.); (S.-M.H.); Tel.: +886-7-6151100 (ext. 7914) (Y.-H.H.); +886-2-27361661 (ext. 6558) (S.-M.H.)
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Diazoxide Preconditioning of Nonhuman Primate Pancreas Improves Islet Isolation Outcomes by Mitochondrial Protection. Pancreas 2020; 49:706-713. [PMID: 32433410 DOI: 10.1097/mpa.0000000000001557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
OBJECTIVES Previously, we showed that diazoxide (DZ), an effective ischemic preconditioning agent, protected rodent pancreas against ischemia-reperfusion injury. Here, we further investigate whether DZ supplementation to University of Wisconsin (UW) solution during pancreas procurement and islet isolation has similar cytoprotection in a preclinical nonhuman primate model. METHODS Cynomolgus monkey pancreata were flushed with UW or UW + 150 μM DZ during procurement and preserved for 8 hours before islet isolation. RESULTS First, a significantly higher islet yield was observed in UW + DZ than in UW (57,887 vs 23,574 IEq/pancreas and 5396 vs 1646 IEq/g). Second, the DZ treated islets had significantly lower apoptotic cells per islet (1.64% vs 9.85%). Third, DZ significantly inhibited ROS surge during reperfusion with a dose-response manner. Fourth, DZ improved in vitro function of isolated islets determined by mitochondrial potentials and calcium influx in responses to glucose and KCI. Fifth, the DZ treated islets had much higher cure rate and better glycemia control in diabetic mice transplant model. CONCLUSIONS This study showed a strong mitochondrial protection of DZ on nonhuman primate islets against ischemia-reperfusion injury that provides strong evidence for its clinical application in islet and pancreas transplantation.
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Zhang YQ, Tian F, Zhou Y, Chen YD, Li B, Ma Q, Zhang Y. Nicorandil attenuates carotid intimal hyperplasia after balloon catheter injury in diabetic rats. Cardiovasc Diabetol 2016; 15:62. [PMID: 27059601 PMCID: PMC4826484 DOI: 10.1186/s12933-016-0377-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 03/25/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Diabetic patients suffer from undesired intimal hyperplasia after angioplasty. Nicorandil has a trend to reduce the rate of target lesion revascularization. However, whether nicorandil inhibits intimal hyperplasia and the possible mechanisms underlying it remain to be determined. We aimed at assessing the effect of nicorandil on intimal hyperplasia in diabetic rats. METHODS After intraperitoneal injection of streptozotocin (STZ, 50 mg/kg), balloon injury model was established in carotid arteries of diabetic rats. Rats were randomized to vehicle, nicorandil (15 mg/kg/day) or 5-hydroxydecanoate (5-HD, 10 mg/kg/day), a mitochondrial ATP-sensitive potassium channel (mitoKATP channel)-selective antagonist. Perivascular delivery of εPKC siRNA was conducted to determine the role of εPKC pathway in intimal hyperplasia. In hyperglycemia environment (25 mM glucose), primary culture of vascular smooth muscle cells (VSMCs) were treated with nicorandil or 5-HD. Cell proliferation and cell migration were analyzed. RESULTS Intimal hyperplasia significantly increased 14 days after balloon injury in diabetic rats (p < 0.01). Nicorandil inhibited intima development, reduced inflammation and prevented cell proliferation in balloon-injured arteries (p < 0.01). The protective effects of nicorandil were reversed by 5-HD (p < 0.05). εPKC was activated in balloon-injured arteries (p < 0.01). Nicorandil inhibited εPKC activation by opening mitoKATP channel. Perivascular delivery of εPKC siRNA inhibited intimal hyperplasia, inflammation and cell proliferation (p < 0.01). High glucose-induced VSMCs proliferation and migration were inhibited by nicorandil. εPKC activation induced by high glucose was also inhibited by nicorandil and that is partially reversed by 5-HD. εPKC knockdown prevented VSMCs proliferation and migration (p < 0.01). CONCLUSIONS Our study demonstrates that nicorandil inhibits intimal hyperplasia in balloon-injured arteries in diabetic rats. Nicorandil also prevents VSMCs proliferation and migration induced by high glucose. The beneficial effect of nicorandil is conducted via opening mitoKATP channel and inhibiting εPKC activation.
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Affiliation(s)
- Ying Qian Zhang
- Department of Cardiology, Chinese PLA General Hospital, 28 Fuxing Rd, Beijing, 100853, China
| | - Feng Tian
- Department of Cardiology, Chinese PLA General Hospital, 28 Fuxing Rd, Beijing, 100853, China
| | - Ying Zhou
- Department of Cardiology, Chinese PLA General Hospital, 28 Fuxing Rd, Beijing, 100853, China
| | - Yun Dai Chen
- Department of Cardiology, Chinese PLA General Hospital, 28 Fuxing Rd, Beijing, 100853, China.
| | - Bo Li
- Department of Cardiology, Chinese PLA General Hospital, 28 Fuxing Rd, Beijing, 100853, China
| | - Qiang Ma
- Department of Cardiology, Chinese PLA General Hospital, 28 Fuxing Rd, Beijing, 100853, China
| | - Ying Zhang
- Department of Cardiology, Chinese PLA General Hospital, 28 Fuxing Rd, Beijing, 100853, China
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Hamilton D, Rugg C, Davis N, Kvezereli M, Tafti BA, Busque S, Fontaine M. A Preconditioning Regimen with a PKCε Activator Improves Islet Graft Function in a Mouse Transplant Model. Cell Transplant 2014; 23:913-9. [DOI: 10.3727/096368913x665567] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Transplantation of islets isolated from deceased donor pancreata is an attractive method of β-cell replacement therapy for patients with type 1 diabetes (T1D). However, the loss of islet cell viability and function during the peritransplant period is a limiting factor to long-term islet engraftment. Activation of the isoenzyme PKCe may improve islet survival and function. The current study assesses the effects of PKCe activation on islet graft function in a syngeneic streptozotocin-induced diabetic mouse model. Islets were isolated from wild-type BALB/c mice preconditioned with either a PKCe activator (ψεRACK) or a TAT carrier control peptide. Islets were further treated with the same agents during isolation, purification, and incubation prior to transplantation. Two hundred seventy-five islet equivalents were transplanted under the kidney capsule of streptozotocin-induced diabetic BALB/c mice. Islet function was assessed by measurement of blood glucose levels every 3 days for 42 days after transplant and through an intraperitoneal glucose tolerance test (IPGTT). The time for return to euglycemia in mice transplanted with islets treated with ψεRACK was improved at 14 ± 6 days versus 21 ± 6 days with TAT-treated islets. The IPGTT showed a 50% reduction in the area under the curve associated with an improved insulin response in mice transplanted with ψεRACK-treated islets compared to TAT-treated islets. A preconditioning regimen using PKCe agonist before pancreatic recovery and during islet isolation improves islet graft function and resistance to high glucose stress after transplantation.
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Affiliation(s)
- Diana Hamilton
- Department of Pathology, Stanford University, Stanford, CA, USA
| | - Caitlin Rugg
- Department of Pathology, Stanford University, Stanford, CA, USA
| | - Nicolynn Davis
- Department of Pathology, Stanford University, Stanford, CA, USA
| | | | | | - Stephan Busque
- Department of Surgery, Stanford University, Stanford, CA, USA
| | - Magali Fontaine
- Department of Pathology, Stanford University, Stanford, CA, USA
- Department of Pathology, University of Maryland School of Medicine, Baltimore, MD, USA
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Ma Z, Moruzzi N, Catrina SB, Hals I, Oberholzer J, Grill V, Björklund A. Preconditioning with associated blocking of Ca2+ inflow alleviates hypoxia-induced damage to pancreatic β-cells. PLoS One 2013; 8:e67498. [PMID: 23935835 PMCID: PMC3723782 DOI: 10.1371/journal.pone.0067498] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Accepted: 05/20/2013] [Indexed: 01/06/2023] Open
Abstract
Objective Beta cells of pancreatic islets are susceptible to functional deficits and damage by hypoxia. Here we aimed to characterize such effects and to test for and pharmacological means to alleviate a negative impact of hypoxia. Methods and Design Rat and human pancreatic islets were subjected to 5.5 h of hypoxia after which functional and viability parameters were measured subsequent to the hypoxic period and/or following a 22 h re-oxygenation period. Preconditioning with diazoxide or other agents was usually done during a 22 h period prior to hypoxia. Results Insulin contents decreased by 23% after 5.5 h of hypoxia and by 61% after a re-oxygenation period. Preconditioning with diazoxide time-dependently alleviated these hypoxia effects in rat and human islets. Hypoxia reduced proinsulin biosynthesis (3H-leucine incorporation into proinsulin) by 35%. Preconditioning counteracted this decrease by 91%. Preconditioning reduced hypoxia-induced necrosis by 40%, attenuated lowering of proteins of mitochondrial complexes I–IV and enhanced stimulation of HIF-1-alpha and phosphorylated AMPK proteins. Preconditioning by diazoxide was abolished by co-exposure to tolbutamide or elevated potassium (i.e. conditions which increase Ca2+ inflow). Preconditioning with nifedipine, a calcium channel blocker, partly reproduced effects of diazoxide. Both diazoxide and nifedipine moderately reduced basal glucose oxidation whereas glucose-induced oxygen consumption (tested with diazoxide) was unaffected. Preconditioning with diaxoxide enhanced insulin contents in transplants of rat islets to non-diabetic rats and lowered hyperglycemia vs. non-preconditioned islets in streptozotocin-diabetic rats. Preconditioning of human islet transplants lowered hyperglycemia in streptozotocin-diabetic nude mice. Conclusions 1) Prior blocking of Ca2+ inflow associates with lesser hypoxia-induced damage, 2) preconditioning affects basal mitochondrial metabolism and accelerates activation of hypoxia-reactive and potentially protective factors, 3) results indicate that preconditioning by K+-ATP-channel openers has therapeutic potential for islet transplantations.
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Affiliation(s)
- Zuheng Ma
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| | - Noah Moruzzi
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| | - Sergiu-Bogdan Catrina
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| | - Ingrid Hals
- Institute of Cancer Research and Molecular Medicine, The Medical Faculty, Norwegian University of Science and Technology, Trondheim, Norway
| | - José Oberholzer
- Department of Transplant/Surgery, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Valdemar Grill
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
- Institute of Cancer Research and Molecular Medicine, The Medical Faculty, Norwegian University of Science and Technology, Trondheim, Norway
- Department of Endocrinology, St. Olav University Hospital, 7006 Trondheim, Norway
| | - Anneli Björklund
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
- * E-mail:
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de Tullio P, Servais AC, Fillet M, Gillotin F, Somers F, Chiap P, Lebrun P, Pirotte B. Hydroxylated Analogues of ATP-Sensitive Potassium Channel Openers Belonging to the Group of 6- and/or 7-Substituted 3-Isopropylamino-4H-1,2,4-benzothiadiazine 1,1-Dioxides: Toward an Improvement in Sulfonylurea Receptor 1 Selectivity and Metabolism Stability. J Med Chem 2011; 54:8353-61. [DOI: 10.1021/jm200786z] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Pascal de Tullio
- Drug Research Center, Laboratoire de Chimie Pharmaceutique, Université de Liège, Centre Hospitalier Universitaire de Liège, 1 Avenue de l'Hôpital, B36, 4000 Liège, Belgium.
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Xue Y, Xie N, Lin Y, Xu J, Han Y, Wang S, Jiang H, Chi Z. Role of PI3K/Akt in diazoxide preconditioning against rat hippocampal neuronal death in pilocarpine-induced seizures. Brain Res 2011; 1383:135-40. [DOI: 10.1016/j.brainres.2011.01.037] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2010] [Revised: 01/11/2011] [Accepted: 01/12/2011] [Indexed: 12/21/2022]
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Börjesson A, Rønn SG, Karlsen AE, Billestrup N, Sandler S. β-cell specific overexpression of suppressor of cytokine signalling-3 does not protect against multiple low dose streptozotocin induced type 1 diabetes in mice. Immunol Lett 2011; 136:74-9. [PMID: 21237203 DOI: 10.1016/j.imlet.2010.12.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2010] [Revised: 10/27/2010] [Accepted: 12/21/2010] [Indexed: 12/21/2022]
Abstract
We investigated the impact of β-cell specific overexpression of suppressor of cytokine signalling-3 (SOCS-3) on the development of multiple low dose streptozotocin (MLDSTZ) induced Type 1 diabetes and the possible mechanisms involved. MLDSTZ treatment was administered to RIP-SOCS-3 transgenic and wild-type (wt) mice and progression of hyperglycemia monitored. Isolated islets from both strains were exposed to human IL-1β (25U/ml) or a combination of human IL-1β (25U/ml) and murine IFN-γ (1000U/ml) for 24h or 48h and we investigated the expression of IL-1 receptor antagonist (IL-1Ra) mRNA in islet cells and secretion of IL-1Ra into culture medium. MLDSTZ treatment caused gradual hyperglycemia both in the wt mice and in the transgenic mice with the latter tending to be more sensitive. In vitro experiments on wt and transgenic islets did not reveal any differences in sensitivity to damaging effects of STZ. Exposure of wt islets to IL-1β or IL-1β+IFN-γ seemed to lead to a failing IL-1Ra response from SOCS-3 transgenic islets. It could be that an increased expression of a possible protective molecule against β-cell destruction may lead to a dampered response of another putative protective molecule. This may have counteracted a protective effect against MLDSTZ in SOCS-3 transgenic mice.
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Affiliation(s)
- A Börjesson
- Department of Medical Cell Biology, Uppsala University, SE-751 23, Uppsala, Sweden.
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Drews G, Krippeit-Drews P, Düfer M. Electrophysiology of islet cells. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 654:115-63. [PMID: 20217497 DOI: 10.1007/978-90-481-3271-3_7] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Stimulus-Secretion Coupling (SSC) of pancreatic islet cells comprises electrical activity. Changes of the membrane potential (V(m)) are regulated by metabolism-dependent alterations in ion channel activity. This coupling is best explored in beta-cells. The effect of glucose is directly linked to mitochondrial metabolism as the ATP/ADP ratio determines the open probability of ATP-sensitive K(+) channels (K(ATP) channels). Nucleotide sensitivity and concentration in the direct vicinity of the channels are controlled by several factors including phospholipids, fatty acids, and kinases, e.g., creatine and adenylate kinase. Closure of K(ATP) channels leads to depolarization of beta-cells via a yet unknown depolarizing current. Ca(2+) influx during action potentials (APs) results in an increase of the cytosolic Ca(2+) concentration ([Ca(2+)](c)) that triggers exocytosis. APs are elicited by the opening of voltage-dependent Na(+) and/or Ca(2+) channels and repolarized by voltage- and/or Ca(2+)-dependent K(+) channels. At a constant stimulatory glucose concentration APs are clustered in bursts that are interrupted by hyperpolarized interburst phases. Bursting electrical activity induces parallel fluctuations in [Ca(2+)](c) and insulin secretion. Bursts are terminated by I(Kslow) consisting of currents through Ca(2+)-dependent K(+) channels and K(ATP) channels. This review focuses on structure, characteristics, physiological function, and regulation of ion channels in beta-cells. Information about pharmacological drugs acting on K(ATP) channels, K(ATP) channelopathies, and influence of oxidative stress on K(ATP) channel function is provided. One focus is the outstanding significance of L-type Ca(2+) channels for insulin secretion. The role of less well characterized beta-cell channels including voltage-dependent Na(+) channels, volume sensitive anion channels (VSACs), transient receptor potential (TRP)-related channels, and hyperpolarization-activated cyclic nucleotide-gated (HCN) channels is discussed. A model of beta-cell oscillations provides insight in the interplay of the different channels to induce and maintain electrical activity. Regulation of beta-cell electrical activity by hormones and the autonomous nervous system is discussed. alpha- and delta-cells are also equipped with K(ATP) channels, voltage-dependent Na(+), K(+), and Ca(2+) channels. Yet the SSC of these cells is less clear and is not necessarily dependent on K(ATP) channel closure. Different ion channels of alpha- and delta-cells are introduced and SSC in alpha-cells is described in special respect of paracrine effects of insulin and GABA secreted from beta-cells.
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Affiliation(s)
- Gisela Drews
- Institute of Pharmacy, Department of Pharmacology and Clinical Pharmacy, University of Tübingen, 72076 Tübingen, Germany.
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Pirotte B, de Tullio P, Nguyen QA, Somers F, Fraikin P, Florence X, Wahl P, Hansen JB, Lebrun P. Chloro-substituted 3-alkylamino-4H-1,2,4-benzothiadiazine 1,1-dioxides as ATP-sensitive potassium channel activators: impact of the position of the chlorine atom on the aromatic ring on activity and tissue selectivity. J Med Chem 2010; 53:147-54. [PMID: 19919106 DOI: 10.1021/jm9010093] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The synthesis of 5-chloro-, 6-chloro-, and 8-chloro-substituted 3-alkylamino/cycloalkylamino-4H-1,2,4-benzothiadiazine 1,1-dioxides is described. Their inhibitory effect on the insulin releasing process and their vasorelaxant activity was compared to that of previously reported 7-chloro-3-alkylamino/cycloalkylamino-4H-1,2,4-benzothiadiazine 1,1-dioxides. "5-Chloro" compounds were found to be essentially inactive on both the insulin-secreting and the smooth muscle cells. By contrast, "8-chloro" and "6-chloro" compounds were found to be active on insulin-secreting cells, with the "6-chloro" derivatives emerging as the most potent drugs. Moreover, the "6-chloro" analogues exhibited less myorelaxant activity than their "7-chloro" counterparts. 8-Chloro-3-isopropylamino-4H-1,2,4-benzothiadiazine 1,1-dioxide (25b) and 6-chloro-3-cyclobutylamino-4H-1,2,4-benzothiadiazine 1,1-dioxide (19e) were further identified as K(ATP) channel openers by radioisotopic measurements conducted on insulin-secreting cells. Likewise, current recordings on HEK293 cells expressing human SUR1/Kir6.2 channels confirmed the highly potent activity of 19e (EC(50) = 80 nM) on such types of K(ATP) channels. The present work indicates that 6-chloro-3-alkylamino/cycloalkylamino-4H-1,2,4-benzothiadiazine 1,1-dioxides appear to be more attractive than their previously described 7-chloro-substituted analogues as original drugs activating the SUR1/Kir6.2 K(ATP) channels.
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Affiliation(s)
- Bernard Pirotte
- Laboratoire de Chimie Pharmaceutique, Centre Interfacultaire de Recherche du Medicament (Drug Research Center), Universite de Liege, 1 Avenue de l'Hopital, B-4000 Liege, Belgium.
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Grill V, Radtke M, Qvigstad E, Kollind M, Björklund A. Beneficial effects of K-ATP channel openers in diabetes: an update on mechanisms and clinical experiences. Diabetes Obes Metab 2009; 11 Suppl 4:143-8. [PMID: 19817796 DOI: 10.1111/j.1463-1326.2009.01119.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Stresses associated with the diabetic state participate in the demise of beta-cells and therapies that eliminate or reduce such stresses are much needed. K-ATP channel openers, of which diazoxide is the most studied, are potentially useful because experimental studies show that they can counteract chronic over-stimulation of beta-cells and protect against toxic conditions, including relative hypoxia. Several mechanisms may underlie the beneficial effects of diazoxide; these may include both indirect (counteracting over-stimulation) and direct mitochondrial effects. Side effects of diazoxide have limited its use in human trials. We have tested lower doses than previously of diazoxide and thereby largely eliminated side effects. In this setting, we demonstrate positive effects on beta-cell function in type 2 diabetic patients who were simultaneously treated with bedtime insulin. However, such effects were absent in insulin-naïve patients. In newly diagnosed type 1 diabetic patients, a 6-month intervention with diazoxide failed to result in better preservation of beta-cell function. K-ATP channel openers have a potential to improve beta-cell function in subgroups of type 2 diabetes patients. Analogues of diazoxide with more potency in relation to side effects would heighten the possibilities for K-ATP channel openers to be of therapeutic use in type 1 diabetes.
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Affiliation(s)
- V Grill
- Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway.
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Gier B, Krippeit-Drews P, Sheiko T, Aguilar-Bryan L, Bryan J, Düfer M, Drews G. Suppression of KATP channel activity protects murine pancreatic beta cells against oxidative stress. J Clin Invest 2009; 119:3246-56. [PMID: 19805912 DOI: 10.1172/jci38817] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2009] [Accepted: 07/29/2009] [Indexed: 12/21/2022] Open
Abstract
The enhanced oxidative stress associated with type 2 diabetes mellitus contributes to disease pathogenesis. We previously identified plasma membrane-associated ATP-sensitive K+ (KATP) channels of pancreatic beta cells as targets for oxidants. Here, we examined the effects of genetic and pharmacologic ablation of KATP channels on loss of mouse beta cell function and viability following oxidative stress. Using mice lacking the sulfonylurea receptor type 1 (Sur1) subunit of KATP channels, we found that, compared with insulin secretion by WT islets, insulin secretion by Sur1-/- islets was less susceptible to oxidative stress induced by the oxidant H2O2. This was likely, at least in part, a result of the reduced ability of H2O2 to hyperpolarize plasma membrane potential and reduce cytosolic free Ca2+ concentration ([Ca2+]c) in the Sur1-/- beta cells. Remarkably, Sur1-/- beta cells were less prone to apoptosis induced by H2O2 or an NO donor than WT beta cells, despite an enhanced basal rate of apoptosis. This protective effect was attributed to upregulation of the antioxidant enzymes SOD, glutathione peroxidase, and catalase. Upregulation of antioxidant enzymes and reduced sensitivity of Sur1-/- cells to H2O2-induced apoptosis were mimicked by treatment with the sulfonylureas tolbutamide and gliclazide. Enzyme upregulation and protection against oxidant-induced apoptosis were abrogated by agents lowering [Ca2+]c. Sur1-/- mice were less susceptible than WT mice to streptozotocin-induced beta cell destruction and subsequent hyperglycemia and death, which suggests that loss of KATP channel activity may protect against streptozotocin-induced diabetes in vivo.
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Affiliation(s)
- Belinda Gier
- Institute of Pharmacy, Department of Pharmacology, University of Tübingen, Tübingen, Germany
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