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Efthymiou S, Scala M, Nagaraj V, Ochenkowska K, Komdeur FL, Liang RA, Abdel-Hamid MS, Sultan T, Barøy T, Van Ghelue M, Vona B, Maroofian R, Zafar F, Alkuraya FS, Zaki MS, Severino M, Duru KC, Tryon RC, Brauteset LV, Ansari M, Hamilton M, van Haelst MM, van Haaften G, Zara F, Houlden H, Samarut É, Nichols CG, Smeland MF, McClenaghan C. Novel loss-of-function variants expand ABCC9-related intellectual disability and myopathy syndrome. Brain 2024; 147:1822-1836. [PMID: 38217872 PMCID: PMC11068106 DOI: 10.1093/brain/awae010] [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: 06/25/2023] [Revised: 11/22/2023] [Accepted: 12/30/2023] [Indexed: 01/15/2024] Open
Abstract
Loss-of-function mutation of ABCC9, the gene encoding the SUR2 subunit of ATP sensitive-potassium (KATP) channels, was recently associated with autosomal recessive ABCC9-related intellectual disability and myopathy syndrome (AIMS). Here we identify nine additional subjects, from seven unrelated families, harbouring different homozygous loss-of-function variants in ABCC9 and presenting with a conserved range of clinical features. All variants are predicted to result in severe truncations or in-frame deletions within SUR2, leading to the generation of non-functional SUR2-dependent KATP channels. Affected individuals show psychomotor delay and intellectual disability of variable severity, microcephaly, corpus callosum and white matter abnormalities, seizures, spasticity, short stature, muscle fatigability and weakness. Heterozygous parents do not show any conserved clinical pathology but report multiple incidences of intra-uterine fetal death, which were also observed in an eighth family included in this study. In vivo studies of abcc9 loss-of-function in zebrafish revealed an exacerbated motor response to pentylenetetrazole, a pro-convulsive drug, consistent with impaired neurodevelopment associated with an increased seizure susceptibility. Our findings define an ABCC9 loss-of-function-related phenotype, expanding the genotypic and phenotypic spectrum of AIMS and reveal novel human pathologies arising from KATP channel dysfunction.
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Affiliation(s)
- Stephanie Efthymiou
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Marcello Scala
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, 16147 Genoa, Italy
- U.O.C. Genetica Medica, IRCCS Istituto Giannina Gaslini, 16147 Genoa, Italy
| | - Vini Nagaraj
- Center for Advanced Biotechnology and Medicine, and Departments of Pharmacology and Medicine, Robert Wood Johnson Medical School, Rutgers the State University of New Jersey, Piscatway, NJ 08854, USA
| | - Katarzyna Ochenkowska
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), and Department of Neuroscience, Université de Montréal, Montreal H2X 0A9, Quebec, Canada
| | - Fenne L Komdeur
- Section Clinical Genetics, Department of Human Genetics and Amsterdam Reproduction and Development, Amsterdam University Medical Centers, 1105 AZ, Amsterdam, The Netherlands
| | - Robin A Liang
- Department of Medical Genetics, Division of Child and Adolescent Health, University Hospital of North Norway, 9019 Tromsø, Norway
| | - Mohamed S Abdel-Hamid
- Medical Molecular Genetics Department, Human Genetics and Genome Research Institute, National Research Centre, Cairo 12622, Egypt
| | - Tipu Sultan
- Department of Pediatric Neurology, Children Hospital, University of Child Health Sciences, Lahore, Punjab 54000, Pakistan
| | - Tuva Barøy
- Department of Medical Genetics, Oslo University Hospital, 0450 Oslo, Norway
| | - Marijke Van Ghelue
- Department of Medical Genetics, Division of Child and Adolescent Health, University Hospital of North Norway, 9019 Tromsø, Norway
| | - Barbara Vona
- Institute of Human Genetics and Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37073 Göttingen, Germany
| | - Reza Maroofian
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Faisal Zafar
- Department of Paediatric Neurology, Children’s Hospital and Institute of Child Health, Multan, Punjab 60000, Pakistan
| | - Fowzan S Alkuraya
- Department of Translational Genomics, Center for Genomic Medicine, King Faisal Specialist Hospital and Research Center, Riyadh 12713, Saudi Arabia
| | - Maha S Zaki
- Clinical Genetics Department, Human Genetics and Genome Research Institute, National Research Centre, Cairo 12622, Egypt
| | | | - Kingsley C Duru
- Center for Advanced Biotechnology and Medicine, and Departments of Pharmacology and Medicine, Robert Wood Johnson Medical School, Rutgers the State University of New Jersey, Piscatway, NJ 08854, USA
| | - Robert C Tryon
- Department of Cell Biology and Physiology, and Center for the Investigation of Membrane Excitability Diseases (CIMED), Washington University, St Louis, MO 63110, USA
| | - Lin Vigdis Brauteset
- Division of Habilitation for Children, Innlandet Hospital Sanderud, Hamar 2312, Norway
| | - Morad Ansari
- South East Scotland Genetic Service, Western General Hospital, Edinburgh EH4 2XU, UK
| | - Mark Hamilton
- West of Scotland Clinical Genetics Service, Queen Elizabeth University Hospital, Glasgow G51 4TF, UK
| | - Mieke M van Haelst
- Section Clinical Genetics, Department of Human Genetics and Amsterdam Reproduction and Development, Amsterdam University Medical Centers, 1105 AZ, Amsterdam, The Netherlands
| | - Gijs van Haaften
- Department of Genetics, University Medical Center, Utrecht, 3584 CX, The Netherlands
| | - Federico Zara
- U.O.C. Genetica Medica, IRCCS Istituto Giannina Gaslini, 16147 Genoa, Italy
| | - Henry Houlden
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Éric Samarut
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), and Department of Neuroscience, Université de Montréal, Montreal H2X 0A9, Quebec, Canada
| | - Colin G Nichols
- Department of Cell Biology and Physiology, and Center for the Investigation of Membrane Excitability Diseases (CIMED), Washington University, St Louis, MO 63110, USA
| | - Marie F Smeland
- Department of Pediatric Rehabilitation, University Hospital of North Norway, 9019 Tromsø, Norway
- Institute of Clinical Medicine, UiT The Arctic University of Norway, 9019, Tromsø, Norway
| | - Conor McClenaghan
- Center for Advanced Biotechnology and Medicine, and Departments of Pharmacology and Medicine, Robert Wood Johnson Medical School, Rutgers the State University of New Jersey, Piscatway, NJ 08854, USA
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2
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Doucette A, Johnson K, Hulke S, Mujteba S, Miller E, Meyer B, Dosa PI, Klein AH. K ATP Channel Prodrugs Reduce Inflammatory and Neuropathic Hypersensitivity, Morphine-Induced Hypersensitivity, and Precipitated Withdrawal in Mice. J Pharmacol Exp Ther 2023; 387:18-26. [PMID: 36931644 PMCID: PMC10519579 DOI: 10.1124/jpet.122.001522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 02/14/2023] [Accepted: 03/06/2023] [Indexed: 03/19/2023] Open
Abstract
Previous studies show ATP-sensitive potassium (KATP) channel openers can reduce hypersensitivity associated with chronic pain models in rodents, and reduce morphine tolerance. Many agonists of KATP channels are not soluble in physiologically relevant vehicles, requiring adaptation for clinical use. This study compared the antinociceptive activity of novel KATP channel targeting prodrugs, CKLP1, CKLP2, and CF3-CKLP. These prodrugs are activated by endogenous alkaline phosphatase enzymes present in the peripheral and central nervous systems. Analgesic capabilities of intrathecally injected prodrugs were tested in rodent models of spinal nerve ligation (SNL) and complete Freund's adjuvant (CFA) as models for neuropathic and inflammatory pain, respectively. CKLP1 and CKLP2 significantly increased mechanical paw withdrawal thresholds 1-2 hours after intrathecal administration in the SNL model, but all three prodrugs were able to attenuate hypersensitivity up to 7 days after CFA treatment. The reduction of opioid tolerance and opioid-induced hypersensitivity in mice treated chronically with morphine was significantly reduced in CKLP1 and CKLP2 treated animals. Prodrug cleavage was confirmed in mouse spinal cords using liquid chromatography. These studies may aid in the further development of KATP channel prodrugs for use in treatments of chronic pain, opioid tolerance, and withdrawal. SIGNIFICANCE STATEMENT: The cromakalim prodrugs, CKLP1, CKLP2, and CF3-CKLP1 reduced hypersensitivity in inflammatory and neuropathic pain models in male and female mice. CKLP1 and CKLP2 also reduced morphine-induced hypersensitivity in a mouse model of chronic morphine exposure. CKLP2 reduced jumping and rearing behaviors after naloxone-induced precipitated morphine withdrawal. Taken together, CKLP2 demonstrates the potential for development as a non-opioid analgesic drug.
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Affiliation(s)
- Alexis Doucette
- Department of Pharmacy Practice and Pharmaceutical Sciences, University of Minnesota, Duluth, Minnesota (A.D., K.J., S.H., S.M., E.M., B.M., A.H.K.) and Institute for Therapeutics Discovery and Development, Department of Medicinal Chemistry, University of Minnesota, Minneapolis, Minnesota (P.I.D.)
| | - Kayla Johnson
- Department of Pharmacy Practice and Pharmaceutical Sciences, University of Minnesota, Duluth, Minnesota (A.D., K.J., S.H., S.M., E.M., B.M., A.H.K.) and Institute for Therapeutics Discovery and Development, Department of Medicinal Chemistry, University of Minnesota, Minneapolis, Minnesota (P.I.D.)
| | - Shelby Hulke
- Department of Pharmacy Practice and Pharmaceutical Sciences, University of Minnesota, Duluth, Minnesota (A.D., K.J., S.H., S.M., E.M., B.M., A.H.K.) and Institute for Therapeutics Discovery and Development, Department of Medicinal Chemistry, University of Minnesota, Minneapolis, Minnesota (P.I.D.)
| | - Sunna Mujteba
- Department of Pharmacy Practice and Pharmaceutical Sciences, University of Minnesota, Duluth, Minnesota (A.D., K.J., S.H., S.M., E.M., B.M., A.H.K.) and Institute for Therapeutics Discovery and Development, Department of Medicinal Chemistry, University of Minnesota, Minneapolis, Minnesota (P.I.D.)
| | - Elena Miller
- Department of Pharmacy Practice and Pharmaceutical Sciences, University of Minnesota, Duluth, Minnesota (A.D., K.J., S.H., S.M., E.M., B.M., A.H.K.) and Institute for Therapeutics Discovery and Development, Department of Medicinal Chemistry, University of Minnesota, Minneapolis, Minnesota (P.I.D.)
| | - Belle Meyer
- Department of Pharmacy Practice and Pharmaceutical Sciences, University of Minnesota, Duluth, Minnesota (A.D., K.J., S.H., S.M., E.M., B.M., A.H.K.) and Institute for Therapeutics Discovery and Development, Department of Medicinal Chemistry, University of Minnesota, Minneapolis, Minnesota (P.I.D.)
| | - Peter I Dosa
- Department of Pharmacy Practice and Pharmaceutical Sciences, University of Minnesota, Duluth, Minnesota (A.D., K.J., S.H., S.M., E.M., B.M., A.H.K.) and Institute for Therapeutics Discovery and Development, Department of Medicinal Chemistry, University of Minnesota, Minneapolis, Minnesota (P.I.D.)
| | - Amanda H Klein
- Department of Pharmacy Practice and Pharmaceutical Sciences, University of Minnesota, Duluth, Minnesota (A.D., K.J., S.H., S.M., E.M., B.M., A.H.K.) and Institute for Therapeutics Discovery and Development, Department of Medicinal Chemistry, University of Minnesota, Minneapolis, Minnesota (P.I.D.)
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Gando I, Becerra Flores M, Chen IS, Yang HQ, Nakamura TY, Cardozo TJ, Coetzee WA. CL-705G: a novel chemical Kir6.2-specific K ATP channel opener. Front Pharmacol 2023; 14:1197257. [PMID: 37408765 PMCID: PMC10319115 DOI: 10.3389/fphar.2023.1197257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Accepted: 06/01/2023] [Indexed: 07/07/2023] Open
Abstract
Background: KATP channels have diverse roles, including regulation of insulin secretion and blood flow, and protection against biological stress responses and are excellent therapeutic targets. Different subclasses of KATP channels exist in various tissue types due to the unique assemblies of specific pore-forming (Kir6.x) and accessory (SURx) subunits. The majority of pharmacological openers and blockers act by binding to SURx and are poorly selective against the various KATP channel subclasses. Methods and Results: We used 3D models of the Kir6.2/SUR homotetramers based on existing cryo-EM structures of channels in both the open and closed states to identify a potential agonist binding pocket in a functionally critical area of the channel. Computational docking screens of this pocket with the Chembridge Core chemical library of 492,000 drug-like compounds yielded 15 top-ranked "hits", which were tested for activity against KATP channels using patch clamping and thallium (Tl+) flux assays with a Kir6.2/SUR2A HEK-293 stable cell line. Several of the compounds increased Tl+ fluxes. One of them (CL-705G) opened Kir6.2/SUR2A channels with a similar potency as pinacidil (EC50 of 9 µM and 11 μM, respectively). Remarkably, compound CL-705G had no or minimal effects on other Kir channels, including Kir6.1/SUR2B, Kir2.1, or Kir3.1/Kir3.4 channels, or Na+ currents of TE671 medulloblastoma cells. CL-705G activated Kir6.2Δ36 in the presence of SUR2A, but not when expressed by itself. CL-705G activated Kir6.2/SUR2A channels even after PIP2 depletion. The compound has cardioprotective effects in a cellular model of pharmacological preconditioning. It also partially rescued activity of the gating-defective Kir6.2-R301C mutant that is associated with congenital hyperinsulinism. Conclusion: CL-705G is a new Kir6.2 opener with little cross-reactivity with other channels tested, including the structurally similar Kir6.1. This, to our knowledge, is the first Kir-specific channel opener.
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Affiliation(s)
- Ivan Gando
- Biochemistry and Molecular Pharmacology, NYU Grossman School of Medicine, New York, NY, United States
| | - Manuel Becerra Flores
- Biochemistry and Molecular Pharmacology, NYU Grossman School of Medicine, New York, NY, United States
| | - I.-Shan Chen
- Phamacology, Wakayama Medical University, Wakayama, Japan
| | - Hua-Qian Yang
- Cyrus Tang Hematology Center, Soochow University, Suzhou, China
| | | | - Timothy J. Cardozo
- Biochemistry and Molecular Pharmacology, NYU Grossman School of Medicine, New York, NY, United States
| | - William A. Coetzee
- Biochemistry and Molecular Pharmacology, NYU Grossman School of Medicine, New York, NY, United States
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Kobara M, Amano T, Toba H, Nakata T. Nicorandil Suppresses Ischemia-Induced Norepinephrine Release and Ventricular Arrhythmias in Hypertrophic Hearts. Cardiovasc Drugs Ther 2023; 37:53-62. [PMID: 35895166 DOI: 10.1007/s10557-022-07369-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/19/2022] [Indexed: 01/14/2023]
Abstract
PURPOSE Ventricular arrhythmias (VAs) are a common cause of sudden death in acute myocardial infarction (MI), for which hypertension is a major risk factor. Nicorandil opens ATP-sensitive potassium (KATP) channels, which are expressed by nerve terminals and cardiomyocytes and regulate the release of norepinephrine (NE). However, the effects of nicorandil on ischemic NE release in cardiac tissue remain unclear. Therefore, we herein investigated whether nicorandil suppressed interstitial NE concentrations and VAs during acute MI in pressure overload-induced hypertrophic hearts. METHODS Rats were divided into two groups: an abdominal aortic constriction (AAC) group and sham-operated (Sham) group. Four weeks after constriction, cardiac geometry and functions were examined using echocardiography and hemodynamic analyses. Myocardial ischemia was induced by coronary artery occlusion for 100 min with or without the administration of nicorandil. VAs were assessed by electrocardiography, and NE concentrations in the ischemic region were measured using a micro-dialysis method. RESULTS AAC induced left ventricular hypertrophy with diastolic dysfunction. VAs markedly increased in the early phase (0-20 min) of ischemia in both groups and were more frequent in the AAC group. Cardiac interstitial NE concentrations were higher in the AAC group before ischemia and significantly increased during ischemia in both groups. Nicorandil significantly suppressed ischemia-induced VAs and NE increases in the AAC group. CONCLUSION Ischemia-induced VAs were more frequent in hypertrophic hearts and associated with high interstitial concentrations of NE. The attenuation of ischemia-induced increases in NE through neuronal KATP opening by nicorandil may suppress ischemia-induced VAs in hypertrophic hearts.
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Affiliation(s)
- Miyuki Kobara
- Department of Clinical Pharmacology, Division of Pathological Science, Kyoto Pharmaceutical University, 5 Misasagi Nakauchi-cho, Yamashina-ku, Kyoto, 607-8414, Japan.
| | - Toshihiro Amano
- Department of Clinical Pharmacology, Division of Pathological Science, Kyoto Pharmaceutical University, 5 Misasagi Nakauchi-cho, Yamashina-ku, Kyoto, 607-8414, Japan
| | - Hiroe Toba
- Department of Clinical Pharmacology, Division of Pathological Science, Kyoto Pharmaceutical University, 5 Misasagi Nakauchi-cho, Yamashina-ku, Kyoto, 607-8414, Japan
| | - Tetsuo Nakata
- Department of Clinical Pharmacology, Division of Pathological Science, Kyoto Pharmaceutical University, 5 Misasagi Nakauchi-cho, Yamashina-ku, Kyoto, 607-8414, Japan
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5
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Bercea C, Limbu R, Behnam K, Ng KE, Aziz Q, Tinker A, Tamagnini F, Cottrell GS, McNeish AJ. Omega-3 polyunsaturated fatty acid-induced vasodilation in mouse aorta and mesenteric arteries is not mediated by ATP-sensitive potassium channels. Front Physiol 2022; 13:1033216. [PMID: 36589427 PMCID: PMC9797959 DOI: 10.3389/fphys.2022.1033216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Accepted: 11/30/2022] [Indexed: 12/23/2022] Open
Abstract
There is strong evidence that the omega-3 polyunsaturated fatty acids (n-3 PUFAs) docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) have cardioprotective effects. n-3 PUFAs cause vasodilation in hypertensive patients, in part controlled by increased membrane conductance to potassium. As KATP channels play a major role in vascular tone regulation and are involved in hypertension, we aimed to verify whether n-3 PUFA-mediated vasodilation involved the opening of KATP channels. We used a murine model in which the KATP channel pore subunit, Kir6.1, is deleted in vascular smooth muscle. The vasomotor response of preconstricted arteries to physiologically relevant concentrations of DHA and EPA was measured using wire myography, using the channel blocker PNU-37883A. The effect of n-3 PUFAs on potassium currents in wild-type native smooth muscle cells was investigated using whole-cell patch clamping. DHA and EPA induced vasodilation in mouse aorta and mesenteric arteries; relaxations in the aorta were sensitive to KATP blockade with PNU-37883A. Endothelium removal didn't affect relaxation to EPA and caused a small but significant inhibition of relaxation to DHA. In the knock-out model, relaxations to DHA and EPA were unaffected by channel knockdown but were still inhibited by PNU-37883A, indicating that the action of PNU-37883A on relaxation may not reflect inhibition of KATP. In native aortic smooth muscle cells DHA failed to activate KATP currents. We conclude that DHA and EPA cause vasodilation in mouse aorta and mesenteric arteries. Relaxations in blocker-treated arteries from knock-out mice demonstrate that KATP channels are not involved in the n-3 PUFA-induced relaxation.
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Affiliation(s)
- Cristiana Bercea
- McNeish Laboratory, School of Chemistry, Food and Pharmacy, Department of Pharmacology, University of Reading, London, United Kingdom
- Tinker Laboratory, William Harvey Research Institute, Clinical Pharmacology and Precision Medicine, Queen Mary University, London, United Kingdom
| | - Roshan Limbu
- McNeish Laboratory, School of Chemistry, Food and Pharmacy, Department of Pharmacology, University of Reading, London, United Kingdom
| | - Kamila Behnam
- McNeish Laboratory, School of Chemistry, Food and Pharmacy, Department of Pharmacology, University of Reading, London, United Kingdom
| | - Keat-Eng Ng
- Tinker Laboratory, William Harvey Research Institute, Clinical Pharmacology and Precision Medicine, Queen Mary University, London, United Kingdom
| | - Qadeer Aziz
- Tinker Laboratory, William Harvey Research Institute, Clinical Pharmacology and Precision Medicine, Queen Mary University, London, United Kingdom
| | - Andrew Tinker
- Tinker Laboratory, William Harvey Research Institute, Clinical Pharmacology and Precision Medicine, Queen Mary University, London, United Kingdom
| | - Francesco Tamagnini
- McNeish Laboratory, School of Chemistry, Food and Pharmacy, Department of Pharmacology, University of Reading, London, United Kingdom
| | - Graeme S Cottrell
- McNeish Laboratory, School of Chemistry, Food and Pharmacy, Department of Pharmacology, University of Reading, London, United Kingdom
| | - Alister J McNeish
- McNeish Laboratory, School of Chemistry, Food and Pharmacy, Department of Pharmacology, University of Reading, London, United Kingdom
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Nakai-Shimoda H, Himeno T, Okawa T, Miura-Yura E, Sasajima S, Kato M, Yamada Y, Morishita Y, Tsunekawa S, Kato Y, Seino Y, Inoue R, Kondo M, Seino S, Naruse K, Kato K, Mizukami H, Nakamura J, Kamiya H. Kir6.2-deficient mice develop somatosensory dysfunction and axonal loss in the peripheral nerves. iScience 2022; 25:103609. [PMID: 35005553 PMCID: PMC8719014 DOI: 10.1016/j.isci.2021.103609] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 11/27/2021] [Accepted: 12/08/2021] [Indexed: 10/26/2022] Open
Abstract
Glucose-responsive ATP-sensitive potassium channels (KATP) are expressed in a variety of tissues including nervous systems. The depolarization of the membrane potential induced by glucose may lead to hyperexcitability of neurons and induce excitotoxicity. However, the roles of KATP in the peripheral nervous system (PNS) are poorly understood. Here, we determine the roles of KATP in the PNS using KATP-deficient (Kir6.2-deficient) mice. We demonstrate that neurite outgrowth of dorsal root ganglion (DRG) neurons was reduced by channel closers sulfonylureas. However, a channel opener diazoxide elongated the neurite. KATP subunits were expressed in mouse DRG, and expression of certain subunits including Kir6.2 was increased in diabetic mice. In Kir6.2-deficient mice, the current perception threshold, thermal perception threshold, and sensory nerve conduction velocity were impaired. Electron microscopy revealed a reduction of unmyelinated and small myelinated fibers in the sural nerves. In conclusion, KATP may contribute to the development of peripheral neuropathy.
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Affiliation(s)
- Hiromi Nakai-Shimoda
- Division of Diabetes, Department of Internal Medicine, Aichi Medical University School of Medicine, Nagakute 480-1185, Japan
| | - Tatsuhito Himeno
- Division of Diabetes, Department of Internal Medicine, Aichi Medical University School of Medicine, Nagakute 480-1185, Japan.,Department of Innovative Diabetes Therapy, Aichi Medical University School of Medicine, Nagakute 480-1185, Japan
| | - Tetsuji Okawa
- Department of Endocrinology, Gifu Prefectural Tajimi Hospital, Tajimi 507-8522, Japan
| | - Emiri Miura-Yura
- Division of Diabetes, Department of Internal Medicine, Aichi Medical University School of Medicine, Nagakute 480-1185, Japan
| | - Sachiko Sasajima
- Division of Diabetes, Department of Internal Medicine, Aichi Medical University School of Medicine, Nagakute 480-1185, Japan
| | - Makoto Kato
- Division of Diabetes, Department of Internal Medicine, Aichi Medical University School of Medicine, Nagakute 480-1185, Japan
| | - Yuichiro Yamada
- Division of Diabetes, Department of Internal Medicine, Aichi Medical University School of Medicine, Nagakute 480-1185, Japan
| | - Yoshiaki Morishita
- Division of Diabetes, Department of Internal Medicine, Aichi Medical University School of Medicine, Nagakute 480-1185, Japan
| | - Shin Tsunekawa
- Division of Diabetes, Department of Internal Medicine, Aichi Medical University School of Medicine, Nagakute 480-1185, Japan
| | - Yoshiro Kato
- Division of Diabetes, Department of Internal Medicine, Aichi Medical University School of Medicine, Nagakute 480-1185, Japan
| | - Yusuke Seino
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Fujita Health University School of Medicine, Toyoake 470-1192, Aichi, Japan
| | - Rieko Inoue
- Division of Diabetes, Department of Internal Medicine, Aichi Medical University School of Medicine, Nagakute 480-1185, Japan
| | - Masaki Kondo
- Division of Diabetes, Department of Internal Medicine, Aichi Medical University School of Medicine, Nagakute 480-1185, Japan
| | - Susumu Seino
- Division of Molecular and Metabolic Medicine, Department of Physiology and Cell Biology, Kobe University Graduate School of Medicine, Kobe 650-0047, Japan
| | - Keiko Naruse
- Department of Internal Medicine, Aichi Gakuin University School of Dentistry, Nagoya 464-0821, Japan
| | - Koichi Kato
- Department of Medicine, Aichi Gakuin University School of Pharmacy, Nagoya 464-8650, Japan
| | - Hiroki Mizukami
- Department of Pathology and Molecular Medicine, Hirosaki University Graduate School of Medicine, Hirosaki 036-8562, Japan
| | - Jiro Nakamura
- Division of Diabetes, Department of Internal Medicine, Aichi Medical University School of Medicine, Nagakute 480-1185, Japan.,Department of Innovative Diabetes Therapy, Aichi Medical University School of Medicine, Nagakute 480-1185, Japan
| | - Hideki Kamiya
- Division of Diabetes, Department of Internal Medicine, Aichi Medical University School of Medicine, Nagakute 480-1185, Japan
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7
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Singareddy SS, Roessler HI, McClenaghan C, Ikle JM, Tryon RC, van Haaften G, Nichols CG. ATP-sensitive potassium channels in zebrafish cardiac and vascular smooth muscle. J Physiol 2021; 600:299-312. [PMID: 34820842 DOI: 10.1113/jp282157] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 11/18/2021] [Indexed: 12/12/2022] Open
Abstract
ATP-sensitive potassium channels (KATP channels) are hetero-octameric nucleotide-gated ion channels that couple cellular metabolism to excitability in various tissues. In the heart, KATP channels are activated during ischaemia and potentially during adrenergic stimulation. In the vasculature, they are normally active at a low level, reducing vascular tone, but the ubiquitous nature of these channels leads to complex and poorly understood channelopathies as a result of gain- or loss-of-function mutations. Zebrafish (ZF) models of these channelopathies may provide insights to the link between molecular dysfunction and complex pathophysiology, but this requires understanding the tissue dependence of channel activity and subunit specificity. Thus far, direct analysis of ZF KATP expression and functional properties has only been performed in pancreatic β-cells. Using a comprehensive combination of genetically modified fish, electrophysiology and gene expression analysis, we demonstrate that ZF cardiac myocytes (CM) and vascular smooth muscle (VSM) express functional KATP channels of similar subunit composition, structure and metabolic sensitivity to their mammalian counterparts. However, in contrast to mammalian cardiovascular KATP channels, ZF channels are insensitive to potassium channel opener drugs (pinacidil, minoxidil) in both chambers of the heart and in VSM. The results provide a first characterization of the molecular properties of fish KATP channels and validate the use of such genetically modified fish as models of human Cantú syndrome and ABCC9-related Intellectual Disability and Myopathy syndrome. KEY POINTS: Zebrafish cardiac myocytes (CM) and vascular smooth muscle (VSM) express functional KATP channels of similar subunit composition, structure and metabolic sensitivity to their mammalian counterparts. In contrast to mammalian cardiovascular KATP channels, zebrafish channels are insensitive to potassium channel opener drugs (pinacidil, minoxidil) in both chambers of the heart and in VSM. We provide a first characterization of the molecular properties of fish KATP channels and validate the use of such genetically modified fish as models of human Cantú syndrome and ABCC9-related Intellectual Disability and Myopathy syndrome.
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Affiliation(s)
- Soma S Singareddy
- Department of Cell Biology and Physiology and Center for the Investigation of Membrane Excitability Diseases, Washington University in St Louis, St Louis, MO, USA
| | - Helen I Roessler
- Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Conor McClenaghan
- Department of Cell Biology and Physiology and Center for the Investigation of Membrane Excitability Diseases, Washington University in St Louis, St Louis, MO, USA
| | - Jennifer M Ikle
- Department of Cell Biology and Physiology and Center for the Investigation of Membrane Excitability Diseases, Washington University in St Louis, St Louis, MO, USA
| | - Robert C Tryon
- Department of Cell Biology and Physiology and Center for the Investigation of Membrane Excitability Diseases, Washington University in St Louis, St Louis, MO, USA
| | - Gijs van Haaften
- Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Colin G Nichols
- Department of Cell Biology and Physiology and Center for the Investigation of Membrane Excitability Diseases, Washington University in St Louis, St Louis, MO, USA
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8
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Kravenska Y, Checchetto V, Szabo I. Routes for Potassium Ions across Mitochondrial Membranes: A Biophysical Point of View with Special Focus on the ATP-Sensitive K + Channel. Biomolecules 2021; 11:1172. [PMID: 34439838 PMCID: PMC8393992 DOI: 10.3390/biom11081172] [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: 06/22/2021] [Revised: 07/29/2021] [Accepted: 08/02/2021] [Indexed: 12/18/2022] Open
Abstract
Potassium ions can cross both the outer and inner mitochondrial membranes by means of multiple routes. A few potassium-permeable ion channels exist in the outer membrane, while in the inner membrane, a multitude of different potassium-selective and potassium-permeable channels mediate K+ uptake into energized mitochondria. In contrast, potassium is exported from the matrix thanks to an H+/K+ exchanger whose molecular identity is still debated. Among the K+ channels of the inner mitochondrial membrane, the most widely studied is the ATP-dependent potassium channel, whose pharmacological activation protects cells against ischemic damage and neuronal injury. In this review, we briefly summarize and compare the different hypotheses regarding the molecular identity of this patho-physiologically relevant channel, taking into account the electrophysiological characteristics of the proposed components. In addition, we discuss the characteristics of the other channels sharing localization to both the plasma membrane and mitochondria.
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Affiliation(s)
| | | | - Ildiko Szabo
- Department of Biology, University of Padova, 35131 Padova, Italy; (Y.K.); (V.C.)
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9
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Abstract
ATP-sensitive K+ channels (KATP) are inwardly-rectifying potassium channels, broadly expressed throughout the body. KATP is regulated by adenine nucleotides, characteristically being activated by falling ATP and rising ADP levels thus playing an important physiological role by coupling cellular metabolism with membrane excitability. The hetero-octameric channel complex is formed of 4 pore-forming inward rectifier Kir6.x subunits (Kir6.1 or Kir6.2) and 4 regulatory sulfonylurea receptor subunits (SUR1, SUR2A, or SUR2B). These subunits can associate in various tissue-specific combinations to form functional KATP channels with distinct electrophysiological and pharmacological properties. KATP channels play many important physiological roles and mutations in channel subunits can result in diseases such as disorders of insulin handling, cardiac arrhythmia, cardiomyopathy, and neurological abnormalities. The tissue-specific expression of KATP channel subunits coupled with their rich and diverse pharmacology makes KATP channels attractive therapeutic targets in the treatment of endocrine and cardiovascular diseases.
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10
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Huang Y, Hu D, Huang C, Nichols CG. Genetic Discovery of ATP-Sensitive K + Channels in Cardiovascular Diseases. Circ Arrhythm Electrophysiol 2020; 12:e007322. [PMID: 31030551 DOI: 10.1161/circep.119.007322] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The ATP-sensitive K+ (KATP) channels are hetero-octameric protein complexes comprising 4 pore-forming (Kir6.x) subunits and 4 regulatory sulfonylurea receptor (SURx) subunits. They are prominent in myocytes, pancreatic β cells, and neurons and link cellular metabolism with membrane excitability. Using genetically modified animals and genomic analysis in patients, recent studies have implicated certain ATP-sensitive K+ channel subtypes in physiological and pathological processes in a variety of cardiovascular diseases. In this review, we focus on the causal relationship between ATP-sensitive K+ channel activity and pathophysiology in the cardiovascular system, particularly from the perspective of genetic changes in human and animal models.
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Affiliation(s)
- Yan Huang
- Department of Cardiology, Renmin Hospital of Wuhan University; Cardiovascular Research Institute, Wuhan University, PR China (Y.H., D.H., C.H.).,Hubei Key Laboratory of Cardiology, Wuhan, PR China (Y.H., D.H., C.H.)
| | - Dan Hu
- Department of Cardiology, Renmin Hospital of Wuhan University; Cardiovascular Research Institute, Wuhan University, PR China (Y.H., D.H., C.H.).,Hubei Key Laboratory of Cardiology, Wuhan, PR China (Y.H., D.H., C.H.)
| | - Congxin Huang
- Department of Cardiology, Renmin Hospital of Wuhan University; Cardiovascular Research Institute, Wuhan University, PR China (Y.H., D.H., C.H.).,Hubei Key Laboratory of Cardiology, Wuhan, PR China (Y.H., D.H., C.H.)
| | - Colin G Nichols
- Center for the Investigation of Membrane Excitability Diseases and Department of Cell Biology and Physiology, Washington University School of Medicine, Saint Louis, MO (C.G.N.)
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11
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Imtiaz SM, Aleem A, Saqib F, Ormenisan AN, Elena Neculau A, Anastasiu CV. The Potential Involvement of an ATP-Dependent Potassium Channel-Opening Mechanism in the Smooth Muscle Relaxant Properties of Tamarix dioica Roxb. Biomolecules 2019; 9:biom9110722. [PMID: 31717691 PMCID: PMC6920928 DOI: 10.3390/biom9110722] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 11/03/2019] [Accepted: 11/06/2019] [Indexed: 11/16/2022] Open
Abstract
Background: Tamarix dioica is traditionally used to manage various disorders related to smooth muscle in the gastrointestinal, respiratory, and cardiovascular systems. This study was planned to establish a pharmacological basis for the uses of Tamarix dioica in certain medical conditions related to the digestive, respiratory, and cardiovascular systems, and to explore the underlying mechanisms. Methods: A phytochemical study was performed by preliminary methods, followed by HPLC-DAD and spectrometric methods. In vivo evaluation of a crude hydromethanolic extract of T. dioica (TdCr) was done with a castor-oil-provoked diarrheal model in rats to determine its antidiarrheal effect. Ex vivo experiments were done by using isolated tissues to determine the effects on smooth and cardiac muscles and explore the possible mechanisms. Results: TdCr tested positive for flavonoids, saponins, phenols, and tannins as methanolic solvable constituents in a preliminary study. The maximum quantity of gallic acid equivalent (GAE), phenolic, and quercetin equivalent (QE) flavonoid content found was 146 ± 0.001 μg GAE/mg extract and 36.17 ± 2.35 μg QE/mg extract. Quantification based on HPLC-DAD (reverse phase) exposed the presence of rutin at the highest concentration, followed by catechin, gallic acid, myricetin, kaempferol, and apigenin in TdCr. In vivo experiments showed the significant antidiarrheal effect of TdCr (100, 200, and 400 mg/kg) in the diarrheal (castor-oil-provoked) model. Ex vivo experiments revealed spasmolytic, bronchodilatory, and vasorelaxant activities as well as partial cardiac depressant activity, which may be potentiated by a potassium channel opener mechanism, similar to that of cromakalim. The potassium channel (KATP channel)-opening activity was further confirmed by repeating the experiments in glibenclamide-pretreated tissues. Conclusions: In vivo and ex vivo studies of T. dioica provided evidence of the antidiarrheal, spasmolytic, bronchodilator, vasorelaxant, and partial cardiodepressant properties facilitated through the opening of the KATP channel.
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Affiliation(s)
- Syeda Madiha Imtiaz
- Faculty of Pharmacy, Bahauddin Zakariya University, Multan 60800, Pakistan; (S.M.I.); (A.A.); (F.S.)
| | - Ambreen Aleem
- Faculty of Pharmacy, Bahauddin Zakariya University, Multan 60800, Pakistan; (S.M.I.); (A.A.); (F.S.)
| | - Fatima Saqib
- Faculty of Pharmacy, Bahauddin Zakariya University, Multan 60800, Pakistan; (S.M.I.); (A.A.); (F.S.)
| | - Alexe Nicolae Ormenisan
- Department of Engineering and Management of Food and Tourism, Faculty of Tourism, Transilvania University, Brasov 500036, Romania;
| | - Andrea Elena Neculau
- Department of Fundamental, Prophylactical and Clinical Disciplines, Faculty of Medicine, Transilvania University, Brasov 500019, Romania
- Correspondence: ; Tel.: +40-268-412-185
| | - Costin Vlad Anastasiu
- Department of Surgical and Medical Specialities, Faculty of Medicine, Transilvania University, Brasov 500019, Romania;
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12
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Kharade SV, Sanchez-Andres JV, Fulton MG, Shelton EL, Blobaum AL, Engers DW, Hofmann CS, Dadi PK, Lantier L, Jacobson DA, Lindsley CW, Denton JS. Structure-Activity Relationships, Pharmacokinetics, and Pharmacodynamics of the Kir6.2/SUR1-Specific Channel Opener VU0071063. J Pharmacol Exp Ther 2019; 370:350-359. [PMID: 31201216 PMCID: PMC6691189 DOI: 10.1124/jpet.119.257204] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 06/12/2019] [Indexed: 01/14/2023] Open
Abstract
Glucose-stimulated insulin secretion from pancreatic β-cells is controlled by ATP-regulated potassium (KATP) channels composed of Kir6.2 and sulfonylurea receptor 1 (SUR1) subunits. The KATP channel-opener diazoxide is FDA-approved for treating hyperinsulinism and hypoglycemia but suffers from off-target effects on vascular KATP channels and other ion channels. The development of more specific openers would provide critically needed tool compounds for probing the therapeutic potential of Kir6.2/SUR1 activation. Here, we characterize a novel scaffold activator of Kir6.2/SUR1 that our group recently discovered in a high-throughput screen. Optimization efforts with medicinal chemistry identified key structural elements that are essential for VU0071063-dependent opening of Kir6.2/SUR1. VU0071063 has no effects on heterologously expressed Kir6.1/SUR2B channels or ductus arteriole tone, indicating it does not open vascular KATP channels. VU0071063 induces hyperpolarization of β-cell membrane potential and inhibits insulin secretion more potently than diazoxide. VU0071063 exhibits metabolic and pharmacokinetic properties that are favorable for an in vivo probe and is brain penetrant. Administration of VU0071063 inhibits glucose-stimulated insulin secretion and glucose-lowering in mice. Taken together, these studies indicate that VU0071063 is a more potent and specific opener of Kir6.2/SUR1 than diazoxide and should be useful as an in vitro and in vivo tool compound for investigating the therapeutic potential of Kir6.2/SUR1 expressed in the pancreas and brain.
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Affiliation(s)
- Sujay V Kharade
- Departments of Anesthesiology (S.V.K., J.S.D.) and Pediatrics (E.L.S.), Vanderbilt University Medical Center, Nashville, Tennessee; Department of Medicine, Jaume I University, Castellon de la Plana, Spain (J.V.S.-A.); Departments of Chemistry (M.G.F., C.W.L.), Pharmacology (M.G.F., A.L.B., D.W.E., C.S.H., C.W.L., J.S.D.), and Molecular Physiology and Biophysics (P.K.D., D.A.J.), and Mouse Metabolic Phenotyping Core (L.L.), Vanderbilt University, Nashville, Tennessee; and Vanderbilt Center for Neuroscience Drug Discovery, Franklin, Tennessee (D.W.E., A.L.B., C.W.L.)
| | - Juan Vicente Sanchez-Andres
- Departments of Anesthesiology (S.V.K., J.S.D.) and Pediatrics (E.L.S.), Vanderbilt University Medical Center, Nashville, Tennessee; Department of Medicine, Jaume I University, Castellon de la Plana, Spain (J.V.S.-A.); Departments of Chemistry (M.G.F., C.W.L.), Pharmacology (M.G.F., A.L.B., D.W.E., C.S.H., C.W.L., J.S.D.), and Molecular Physiology and Biophysics (P.K.D., D.A.J.), and Mouse Metabolic Phenotyping Core (L.L.), Vanderbilt University, Nashville, Tennessee; and Vanderbilt Center for Neuroscience Drug Discovery, Franklin, Tennessee (D.W.E., A.L.B., C.W.L.)
| | - Mark G Fulton
- Departments of Anesthesiology (S.V.K., J.S.D.) and Pediatrics (E.L.S.), Vanderbilt University Medical Center, Nashville, Tennessee; Department of Medicine, Jaume I University, Castellon de la Plana, Spain (J.V.S.-A.); Departments of Chemistry (M.G.F., C.W.L.), Pharmacology (M.G.F., A.L.B., D.W.E., C.S.H., C.W.L., J.S.D.), and Molecular Physiology and Biophysics (P.K.D., D.A.J.), and Mouse Metabolic Phenotyping Core (L.L.), Vanderbilt University, Nashville, Tennessee; and Vanderbilt Center for Neuroscience Drug Discovery, Franklin, Tennessee (D.W.E., A.L.B., C.W.L.)
| | - Elaine L Shelton
- Departments of Anesthesiology (S.V.K., J.S.D.) and Pediatrics (E.L.S.), Vanderbilt University Medical Center, Nashville, Tennessee; Department of Medicine, Jaume I University, Castellon de la Plana, Spain (J.V.S.-A.); Departments of Chemistry (M.G.F., C.W.L.), Pharmacology (M.G.F., A.L.B., D.W.E., C.S.H., C.W.L., J.S.D.), and Molecular Physiology and Biophysics (P.K.D., D.A.J.), and Mouse Metabolic Phenotyping Core (L.L.), Vanderbilt University, Nashville, Tennessee; and Vanderbilt Center for Neuroscience Drug Discovery, Franklin, Tennessee (D.W.E., A.L.B., C.W.L.)
| | - Anna L Blobaum
- Departments of Anesthesiology (S.V.K., J.S.D.) and Pediatrics (E.L.S.), Vanderbilt University Medical Center, Nashville, Tennessee; Department of Medicine, Jaume I University, Castellon de la Plana, Spain (J.V.S.-A.); Departments of Chemistry (M.G.F., C.W.L.), Pharmacology (M.G.F., A.L.B., D.W.E., C.S.H., C.W.L., J.S.D.), and Molecular Physiology and Biophysics (P.K.D., D.A.J.), and Mouse Metabolic Phenotyping Core (L.L.), Vanderbilt University, Nashville, Tennessee; and Vanderbilt Center for Neuroscience Drug Discovery, Franklin, Tennessee (D.W.E., A.L.B., C.W.L.)
| | - Darren W Engers
- Departments of Anesthesiology (S.V.K., J.S.D.) and Pediatrics (E.L.S.), Vanderbilt University Medical Center, Nashville, Tennessee; Department of Medicine, Jaume I University, Castellon de la Plana, Spain (J.V.S.-A.); Departments of Chemistry (M.G.F., C.W.L.), Pharmacology (M.G.F., A.L.B., D.W.E., C.S.H., C.W.L., J.S.D.), and Molecular Physiology and Biophysics (P.K.D., D.A.J.), and Mouse Metabolic Phenotyping Core (L.L.), Vanderbilt University, Nashville, Tennessee; and Vanderbilt Center for Neuroscience Drug Discovery, Franklin, Tennessee (D.W.E., A.L.B., C.W.L.)
| | - Christopher S Hofmann
- Departments of Anesthesiology (S.V.K., J.S.D.) and Pediatrics (E.L.S.), Vanderbilt University Medical Center, Nashville, Tennessee; Department of Medicine, Jaume I University, Castellon de la Plana, Spain (J.V.S.-A.); Departments of Chemistry (M.G.F., C.W.L.), Pharmacology (M.G.F., A.L.B., D.W.E., C.S.H., C.W.L., J.S.D.), and Molecular Physiology and Biophysics (P.K.D., D.A.J.), and Mouse Metabolic Phenotyping Core (L.L.), Vanderbilt University, Nashville, Tennessee; and Vanderbilt Center for Neuroscience Drug Discovery, Franklin, Tennessee (D.W.E., A.L.B., C.W.L.)
| | - Prasanna K Dadi
- Departments of Anesthesiology (S.V.K., J.S.D.) and Pediatrics (E.L.S.), Vanderbilt University Medical Center, Nashville, Tennessee; Department of Medicine, Jaume I University, Castellon de la Plana, Spain (J.V.S.-A.); Departments of Chemistry (M.G.F., C.W.L.), Pharmacology (M.G.F., A.L.B., D.W.E., C.S.H., C.W.L., J.S.D.), and Molecular Physiology and Biophysics (P.K.D., D.A.J.), and Mouse Metabolic Phenotyping Core (L.L.), Vanderbilt University, Nashville, Tennessee; and Vanderbilt Center for Neuroscience Drug Discovery, Franklin, Tennessee (D.W.E., A.L.B., C.W.L.)
| | - Louise Lantier
- Departments of Anesthesiology (S.V.K., J.S.D.) and Pediatrics (E.L.S.), Vanderbilt University Medical Center, Nashville, Tennessee; Department of Medicine, Jaume I University, Castellon de la Plana, Spain (J.V.S.-A.); Departments of Chemistry (M.G.F., C.W.L.), Pharmacology (M.G.F., A.L.B., D.W.E., C.S.H., C.W.L., J.S.D.), and Molecular Physiology and Biophysics (P.K.D., D.A.J.), and Mouse Metabolic Phenotyping Core (L.L.), Vanderbilt University, Nashville, Tennessee; and Vanderbilt Center for Neuroscience Drug Discovery, Franklin, Tennessee (D.W.E., A.L.B., C.W.L.)
| | - David A Jacobson
- Departments of Anesthesiology (S.V.K., J.S.D.) and Pediatrics (E.L.S.), Vanderbilt University Medical Center, Nashville, Tennessee; Department of Medicine, Jaume I University, Castellon de la Plana, Spain (J.V.S.-A.); Departments of Chemistry (M.G.F., C.W.L.), Pharmacology (M.G.F., A.L.B., D.W.E., C.S.H., C.W.L., J.S.D.), and Molecular Physiology and Biophysics (P.K.D., D.A.J.), and Mouse Metabolic Phenotyping Core (L.L.), Vanderbilt University, Nashville, Tennessee; and Vanderbilt Center for Neuroscience Drug Discovery, Franklin, Tennessee (D.W.E., A.L.B., C.W.L.)
| | - Craig W Lindsley
- Departments of Anesthesiology (S.V.K., J.S.D.) and Pediatrics (E.L.S.), Vanderbilt University Medical Center, Nashville, Tennessee; Department of Medicine, Jaume I University, Castellon de la Plana, Spain (J.V.S.-A.); Departments of Chemistry (M.G.F., C.W.L.), Pharmacology (M.G.F., A.L.B., D.W.E., C.S.H., C.W.L., J.S.D.), and Molecular Physiology and Biophysics (P.K.D., D.A.J.), and Mouse Metabolic Phenotyping Core (L.L.), Vanderbilt University, Nashville, Tennessee; and Vanderbilt Center for Neuroscience Drug Discovery, Franklin, Tennessee (D.W.E., A.L.B., C.W.L.)
| | - Jerod S Denton
- Departments of Anesthesiology (S.V.K., J.S.D.) and Pediatrics (E.L.S.), Vanderbilt University Medical Center, Nashville, Tennessee; Department of Medicine, Jaume I University, Castellon de la Plana, Spain (J.V.S.-A.); Departments of Chemistry (M.G.F., C.W.L.), Pharmacology (M.G.F., A.L.B., D.W.E., C.S.H., C.W.L., J.S.D.), and Molecular Physiology and Biophysics (P.K.D., D.A.J.), and Mouse Metabolic Phenotyping Core (L.L.), Vanderbilt University, Nashville, Tennessee; and Vanderbilt Center for Neuroscience Drug Discovery, Franklin, Tennessee (D.W.E., A.L.B., C.W.L.)
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13
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Pirotte B, Florence X, Goffin E, Lebrun P. 2,2-Dimethyl-3,4-dihydro-2 H-1,4-benzoxazines as isosteres of 2,2-dimethylchromans acting as inhibitors of insulin release and vascular smooth muscle relaxants. MEDCHEMCOMM 2019; 10:431-438. [PMID: 31015906 DOI: 10.1039/c8md00593a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 02/01/2019] [Indexed: 11/21/2022]
Abstract
The present study describes the synthesis and biological evaluation of 4-phenylureido/thioureido-substituted 2,2-dimethyl-3,4-dihydro-2H-1,4-benzoxazines as isosteres of corresponding 2,2-dimethylchromans reported to be pancreatic β-cell KATP channel openers. The benzoxazines were found to be less active as inhibitors of the glucose-induced insulin release than their corresponding chromans, while the myorelaxant activity of some 4-arylureido-substituted benzoxazines was more pronounced than that exhibited by their chroman counterparts. The myorelaxant activity of the most potent benzoxazine 8e was further characterized on rat aortic rings precontracted by 30 mM KCl in the presence of glibenclamide (10 μM) or precontracted by 80 mM extracellular KCl. Our findings indicate that, on vascular smooth muscle cells, the benzoxazine 8e mainly behaved as a calcium entry blocker.
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Affiliation(s)
- Bernard Pirotte
- Laboratoire de Chimie Pharmaceutique , Center for Interdisciplinary Research on Medicines (CIRM) , Université de Liège , Quartier Hôpital , Avenue Hippocrate 15 , B-4000 Liège , Belgium .
| | - Xavier Florence
- Laboratoire de Chimie Pharmaceutique , Center for Interdisciplinary Research on Medicines (CIRM) , Université de Liège , Quartier Hôpital , Avenue Hippocrate 15 , B-4000 Liège , Belgium . .,Laboratoire de Physiologie et Pharmacologie , Université Libre de Bruxelles , Faculté de Médecine , 808 Route de Lennik , B-1070 Bruxelles , Belgium
| | - Eric Goffin
- Laboratoire de Chimie Pharmaceutique , Center for Interdisciplinary Research on Medicines (CIRM) , Université de Liège , Quartier Hôpital , Avenue Hippocrate 15 , B-4000 Liège , Belgium .
| | - Philippe Lebrun
- Laboratoire de Physiologie et Pharmacologie , Université Libre de Bruxelles , Faculté de Médecine , 808 Route de Lennik , B-1070 Bruxelles , Belgium
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14
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Tinker A, Aziz Q, Li Y, Specterman M. ATP‐Sensitive Potassium Channels and Their Physiological and Pathophysiological Roles. Compr Physiol 2018; 8:1463-1511. [DOI: 10.1002/cphy.c170048] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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15
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Pashynska V, Stepanian S, Gömöry Á, Vékey K, Adamowicz L. New cardioprotective agent flokalin and its supramolecular complexes with target amino acids: An integrated mass-spectrometry and quantum-chemical study. J Mol Struct 2017. [DOI: 10.1016/j.molstruc.2017.06.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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16
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Liu X, Duan P, Hu X, Li R, Zhu Q. Altered KATP Channel Subunits Expression and Vascular Reactivity in Spontaneously Hypertensive Rats With Age. J Cardiovasc Pharmacol 2016; 68:143-9. [PMID: 27035370 PMCID: PMC4979625 DOI: 10.1097/fjc.0000000000000394] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 03/12/2016] [Indexed: 11/25/2022]
Abstract
ATP-sensitive potassium (KATP) channels link membrane excitability to metabolic state to regulate a series of biological activities including the vascular tone. However, their ability to influence hypertension is controversial. Here we aim to investigate possible alteration of KATP channel in vascular smooth muscles (VSMs) during hypertension development process. In this study, we used 16-week-old spontaneously hypertensive rats (SHRs), 49-week-old SHRs, and their age-matched Wistar-Kyoto rats to study the expression of VSM KATP subunits at the mRNA and protein level and the function of VSM KATP by observing the relaxation reactivity of isolated aorta rings to KATP modulators. We found that the expression of VSM KATP subunits Kir6.1 and sulfonylurea receptor (SUR2B) decreased during hypertension. Moreover, the expression of SUR2B and Kir6.1 in 49-week-old SHRs decreased much more than that in 16-week-old SHRs. Furthermore, the aorta rings of 49-week-old SHRs showed lower reactivity to diazoxide than 16-week-old SHRs. This study suggests that KATP channels in VSM subunits Kir6.1 and SUR2B contribute to modify the functionality of this channel in hypertension with age.
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MESH Headings
- Age Factors
- Aging/metabolism
- Animals
- Aorta/metabolism
- Aorta/physiopathology
- Blood Pressure/drug effects
- Diazoxide/pharmacology
- Disease Models, Animal
- Dose-Response Relationship, Drug
- Down-Regulation
- Hypertension/drug therapy
- Hypertension/genetics
- Hypertension/metabolism
- Hypertension/physiopathology
- KATP Channels/genetics
- KATP Channels/metabolism
- Male
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Muscle, Smooth, Vascular/physiopathology
- Potassium Channel Blockers/pharmacology
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Rats, Inbred SHR
- Rats, Inbred WKY
- Sulfonylurea Receptors/genetics
- Sulfonylurea Receptors/metabolism
- Vasodilation/drug effects
- Vasodilator Agents/pharmacology
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Affiliation(s)
- Xiaojing Liu
- Department of Cardiology, Chinese PLA General Hospital, Beijing, China; and
| | - Peng Duan
- Department of Cardiology, Chinese PLA General Hospital, Beijing, China; and
| | - Xingxing Hu
- Department of Cardiology, Chinese PLA General Hospital, Beijing, China; and
| | - Ruisheng Li
- Research and Technology Service Center, 302 Hospital of PLA, Beijing, China
| | - Qinglei Zhu
- Department of Cardiology, Chinese PLA General Hospital, Beijing, China; and
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17
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Gao Z, Sierra A, Zhu Z, Koganti SRK, Subbotina E, Maheshwari A, Anderson ME, Zingman LV, Hodgson-Zingman DM. Loss of ATP-Sensitive Potassium Channel Surface Expression in Heart Failure Underlies Dysregulation of Action Potential Duration and Myocardial Vulnerability to Injury. PLoS One 2016; 11:e0151337. [PMID: 26964104 PMCID: PMC4786327 DOI: 10.1371/journal.pone.0151337] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Accepted: 02/26/2016] [Indexed: 11/18/2022] Open
Abstract
The search for new approaches to treatment and prevention of heart failure is a major challenge in medicine. The adenosine triphosphate-sensitive potassium (KATP) channel has been long associated with the ability to preserve myocardial function and viability under stress. High surface expression of membrane KATP channels ensures a rapid energy-sparing reduction in action potential duration (APD) in response to metabolic challenges, while cellular signaling that reduces surface KATP channel expression blunts APD shortening, thus sacrificing energetic efficiency in exchange for greater cellular calcium entry and increased contractile force. In healthy hearts, calcium/calmodulin-dependent protein kinase II (CaMKII) phosphorylates the Kir6.2 KATP channel subunit initiating a cascade responsible for KATP channel endocytosis. Here, activation of CaMKII in a transaortic banding (TAB) model of heart failure is coupled with a 35–40% reduction in surface expression of KATP channels compared to hearts from sham-operated mice. Linkage between KATP channel expression and CaMKII is verified in isolated cardiomyocytes in which activation of CaMKII results in downregulation of KATP channel current. Accordingly, shortening of monophasic APD is slowed in response to hypoxia or heart rate acceleration in failing compared to non-failing hearts, a phenomenon previously shown to result in significant increases in oxygen consumption. Even in the absence of coronary artery disease, failing myocardium can be further injured by ischemia due to a mismatch between metabolic supply and demand. Ischemia-reperfusion injury, following ischemic preconditioning, is diminished in hearts with CaMKII inhibition compared to wild-type hearts and this advantage is largely eliminated when myocardial KATP channel expression is absent, supporting that the myocardial protective benefit of CaMKII inhibition in heart failure may be substantially mediated by KATP channels. Recognition of CaMKII-dependent downregulation of KATP channel expression as a mechanism for vulnerability to injury in failing hearts points to strategies targeting this interaction for potential preventives or treatments.
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Affiliation(s)
- Zhan Gao
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Ana Sierra
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Zhiyong Zhu
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Siva Rama Krishna Koganti
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Ekaterina Subbotina
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Ankit Maheshwari
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Mark E. Anderson
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
- François Abboud Cardiovascular Research Center, University of Iowa, Iowa City, Iowa, United States of America
| | - Leonid V. Zingman
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
- François Abboud Cardiovascular Research Center, University of Iowa, Iowa City, Iowa, United States of America
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa, United States of America
- Veterans Affairs Medical Center, Iowa City, Iowa, United States of America
| | - Denice M. Hodgson-Zingman
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
- François Abboud Cardiovascular Research Center, University of Iowa, Iowa City, Iowa, United States of America
- * E-mail:
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18
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Abstract
KATP channels are integral to the functions of many cells and tissues. The use of electrophysiological methods has allowed for a detailed characterization of KATP channels in terms of their biophysical properties, nucleotide sensitivities, and modification by pharmacological compounds. However, even though they were first described almost 25 years ago (Noma 1983, Trube and Hescheler 1984), the physiological and pathophysiological roles of these channels, and their regulation by complex biological systems, are only now emerging for many tissues. Even in tissues where their roles have been best defined, there are still many unanswered questions. This review aims to summarize the properties, molecular composition, and pharmacology of KATP channels in various cardiovascular components (atria, specialized conduction system, ventricles, smooth muscle, endothelium, and mitochondria). We will summarize the lessons learned from available genetic mouse models and address the known roles of KATP channels in cardiovascular pathologies and how genetic variation in KATP channel genes contribute to human disease.
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Affiliation(s)
- Monique N Foster
- Departments of Pediatrics, Physiology & Neuroscience, and Biochemistry and Molecular Pharmacology, NYU School of Medicine, New York, New York
| | - William A Coetzee
- Departments of Pediatrics, Physiology & Neuroscience, and Biochemistry and Molecular Pharmacology, NYU School of Medicine, New York, New York
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19
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Principalli MA, Dupuis JP, Moreau CJ, Vivaudou M, Revilloud J. Kir6.2 activation by sulfonylurea receptors: a different mechanism of action for SUR1 and SUR2A subunits via the same residues. Physiol Rep 2015; 3:3/9/e12533. [PMID: 26416970 PMCID: PMC4600379 DOI: 10.14814/phy2.12533] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
ATP-sensitive potassium channels (K-ATP channels) play a key role in adjusting the membrane potential to the metabolic state of cells. They result from the unique combination of two proteins: the sulfonylurea receptor (SUR), an ATP-binding cassette (ABC) protein, and the inward rectifier K(+) channel Kir6.2. Both subunits associate to form a heterooctamer (4 SUR/4 Kir6.2). SUR modulates channel gating in response to the binding of nucleotides or drugs and Kir6.2 conducts potassium ions. The activity of K-ATP channels varies with their localization. In pancreatic β-cells, SUR1/Kir6.2 channels are partly active at rest while in cardiomyocytes SUR2A/Kir6.2 channels are mostly closed. This divergence of function could be related to differences in the interaction of SUR1 and SUR2A with Kir6.2. Three residues (E1305, I1310, L1313) located in the linker region between transmembrane domain 2 and nucleotide-binding domain 2 of SUR2A were previously found to be involved in the activation pathway linking binding of openers onto SUR2A and channel opening. To determine the role of the equivalent residues in the SUR1 isoform, we designed chimeras between SUR1 and the ABC transporter multidrug resistance-associated protein 1 (MRP1), and used patch clamp recordings on Xenopus oocytes to assess the functionality of SUR1/MRP1 chimeric K-ATP channels. Our results reveal that the same residues in SUR1 and SUR2A are involved in the functional association with Kir6.2, but they display unexpected side-chain specificities which could account for the contrasted properties of pancreatic and cardiac K-ATP channels.
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Affiliation(s)
- Maria A Principalli
- Institut de Biologie Structurale (IBS), University of Grenoble Alpes, Grenoble, France CNRS, IBS, Grenoble, France CEA, IBS, Grenoble, France
| | - Julien P Dupuis
- Institut Interdisciplinaire de Neurosciences CNRS UMR 5297, Bordeaux, France
| | - Christophe J Moreau
- Institut de Biologie Structurale (IBS), University of Grenoble Alpes, Grenoble, France CNRS, IBS, Grenoble, France CEA, IBS, Grenoble, France
| | - Michel Vivaudou
- Institut de Biologie Structurale (IBS), University of Grenoble Alpes, Grenoble, France CNRS, IBS, Grenoble, France CEA, IBS, Grenoble, France
| | - Jean Revilloud
- Institut de Biologie Structurale (IBS), University of Grenoble Alpes, Grenoble, France CNRS, IBS, Grenoble, France CEA, IBS, Grenoble, France
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20
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Abstract
The field of mitochondrial ion channels has recently seen substantial progress, including the molecular identification of some of the channels. An integrative approach using genetics, electrophysiology, pharmacology, and cell biology to clarify the roles of these channels has thus become possible. It is by now clear that many of these channels are important for energy supply by the mitochondria and have a major impact on the fate of the entire cell as well. The purpose of this review is to provide an up-to-date overview of the electrophysiological properties, molecular identity, and pathophysiological functions of the mitochondrial ion channels studied so far and to highlight possible therapeutic perspectives based on current information.
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21
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Label-free cell phenotypic profiling decodes the composition and signaling of an endogenous ATP-sensitive potassium channel. Sci Rep 2014; 4:4934. [PMID: 24816792 PMCID: PMC4017216 DOI: 10.1038/srep04934] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Accepted: 04/24/2014] [Indexed: 11/27/2022] Open
Abstract
Current technologies for studying ion channels are fundamentally limited because of their inability to functionally link ion channel activity to cellular pathways. Herein, we report the use of label-free cell phenotypic profiling to decode the composition and signaling of an endogenous ATP-sensitive potassium ion channel (KATP) in HepG2C3A, a hepatocellular carcinoma cell line. Label-free cell phenotypic agonist profiling showed that pinacidil triggered characteristically similar dynamic mass redistribution (DMR) signals in A431, A549, HT29 and HepG2C3A, but not in HepG2 cells. Reverse transcriptase PCR, RNAi knockdown, and KATP blocker profiling showed that the pinacidil DMR is due to the activation of SUR2/Kir6.2 KATP channels in HepG2C3A cells. Kinase inhibition and RNAi knockdown showed that the pinacidil activated KATP channels trigger signaling through Rho kinase and Janus kinase-3, and cause actin remodeling. The results are the first demonstration of a label-free methodology to characterize the composition and signaling of an endogenous ATP-sensitive potassium ion channel.
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22
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Hosy E, Vivaudou M. The unusual stoichiometry of ADP activation of the KATP channel. Front Physiol 2014; 5:11. [PMID: 24478723 PMCID: PMC3904077 DOI: 10.3389/fphys.2014.00011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Accepted: 01/07/2014] [Indexed: 11/27/2022] Open
Abstract
KATP channels, oligomers of 4 pore-forming Kir6.2 proteins and 4 sulfonylurea receptors (SUR), sense metabolism by monitoring both cytosolic ATP, which closes the channel by interacting with Kir6.2, and ADP, which opens it via SUR. SUR mutations that alter activation by ADP are a major cause of KATP channelopathies. We examined the mechanism of ADP activation by analysis of single-channel and macropatch recordings from Xenopus oocytes expressing various mixtures of wild-type SUR2A and an ADP-activation-defective mutant. Evaluation of the data by a binomial distribution model suggests that wild-type and mutant SURs freely co-assemble and that channel activation results from interaction of ADP with only 2 of 4 SURs. This finding explains the heterozygous nature of most KATP channelopathies linked to mutations altering ADP activation. It also suggests that the channel deviates from circular symmetry and could function as a dimer-of-dimers.
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Affiliation(s)
- Eric Hosy
- Institut de Biologie Structurale, University Grenoble Alpes Grenoble, France ; Laboratory of Excellence, Ion Channel Science and Therapeutics, CNRS, Institut de Biologie Structurale Grenoble, France ; CEA, DSV, Institut de Biologie Structurale Grenoble, France
| | - Michel Vivaudou
- Institut de Biologie Structurale, University Grenoble Alpes Grenoble, France ; Laboratory of Excellence, Ion Channel Science and Therapeutics, CNRS, Institut de Biologie Structurale Grenoble, France ; CEA, DSV, Institut de Biologie Structurale Grenoble, France
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23
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Martin GM, Chen PC, Devaraneni P, Shyng SL. Pharmacological rescue of trafficking-impaired ATP-sensitive potassium channels. Front Physiol 2013; 4:386. [PMID: 24399968 PMCID: PMC3870925 DOI: 10.3389/fphys.2013.00386] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Accepted: 12/09/2013] [Indexed: 12/25/2022] Open
Abstract
ATP-sensitive potassium (KATP) channels link cell metabolism to membrane excitability and are involved in a wide range of physiological processes including hormone secretion, control of vascular tone, and protection of cardiac and neuronal cells against ischemic injuries. In pancreatic β-cells, KATP channels play a key role in glucose-stimulated insulin secretion, and gain or loss of channel function results in neonatal diabetes or congenital hyperinsulinism, respectively. The β-cell KATP channel is formed by co-assembly of four Kir6.2 inwardly rectifying potassium channel subunits encoded by KCNJ11 and four sulfonylurea receptor 1 subunits encoded by ABCC8. Many mutations in ABCC8 or KCNJ11 cause loss of channel function, thus, congenital hyperinsulinism by hampering channel biogenesis and hence trafficking to the cell surface. The trafficking defects caused by a subset of these mutations can be corrected by sulfonylureas, KATP channel antagonists that have long been used to treat type 2 diabetes. More recently, carbamazepine, an anticonvulsant that is thought to target primarily voltage-gated sodium channels has been shown to correct KATP channel trafficking defects. This article reviews studies to date aimed at understanding the mechanisms by which mutations impair channel biogenesis and trafficking and the mechanisms by which pharmacological ligands overcome channel trafficking defects. Insight into channel structure-function relationships and therapeutic implications from these studies are discussed.
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Affiliation(s)
- Gregory M Martin
- Department of Biochemistry and Molecular Biology, Oregon Health & Science University Portland, OR, USA
| | - Pei-Chun Chen
- Department of Biochemistry and Molecular Biology, Oregon Health & Science University Portland, OR, USA
| | - Prasanna Devaraneni
- Department of Biochemistry and Molecular Biology, Oregon Health & Science University Portland, OR, USA
| | - Show-Ling Shyng
- Department of Biochemistry and Molecular Biology, Oregon Health & Science University Portland, OR, USA
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24
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Zhu Z, Sierra A, Burnett CML, Chen B, Subbotina E, Koganti SRK, Gao Z, Wu Y, Anderson ME, Song LS, Goldhamer DJ, Coetzee WA, Hodgson-Zingman DM, Zingman LV. Sarcolemmal ATP-sensitive potassium channels modulate skeletal muscle function under low-intensity workloads. ACTA ACUST UNITED AC 2013; 143:119-34. [PMID: 24344248 PMCID: PMC3874572 DOI: 10.1085/jgp.201311063] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
ATP-sensitive potassium (KATP) channels have the unique ability to adjust membrane excitability and functions in accordance with the metabolic status of the cell. Skeletal muscles are primary sites of activity-related energy consumption and have KATP channels expressed in very high density. Previously, we demonstrated that transgenic mice with skeletal muscle–specific disruption of KATP channel function consume more energy than wild-type littermates. However, how KATP channel activation modulates skeletal muscle resting and action potentials under physiological conditions, particularly low-intensity workloads, and how this can be translated to muscle energy expenditure are yet to be determined. Here, we developed a technique that allows evaluation of skeletal muscle excitability in situ, with minimal disruption of the physiological environment. Isometric twitching of the tibialis anterior muscle at 1 Hz was used as a model of low-intensity physical activity in mice with normal and genetically disrupted KATP channel function. This workload was sufficient to induce KATP channel opening, resulting in membrane hyperpolarization as well as reduction in action potential overshoot and duration. Loss of KATP channel function resulted in increased calcium release and aggravated activity-induced heat production. Thus, this study identifies low-intensity workload as a trigger for opening skeletal muscle KATP channels and establishes that this coupling is important for regulation of myocyte function and thermogenesis. These mechanisms may provide a foundation for novel strategies to combat metabolic derangements when energy conservation or dissipation is required.
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Affiliation(s)
- Zhiyong Zhu
- Department of Internal Medicine and 2 Fraternal Order of Eagles Diabetes Research Center, University of Iowa Carver College of Medicine, Iowa City, IA 52242
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25
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Aggarwal NT, Shi NQ, Makielski JC. ATP-sensitive potassium currents from channels formed by Kir6 and a modified cardiac mitochondrial SUR2 variant. Channels (Austin) 2013; 7:493-502. [PMID: 24037327 DOI: 10.4161/chan.26181] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Cardiac ATP-sensitive potassium channels (KATP) are found in both the sarcoplasmic reticulum (sarcKATP) and the inner membrane of mitochondria (mitoKATP). SarcKATP are composed of a pore containing subunit Kir6.2 and a regulatory sulfonylurea receptor subunit (SUR2), but the composition of mitoKATP remains unclear. An unusual intra-exonic splice variant of SUR2 (SUR2A-55) was previously identified in mitochondria of mammalian heart and brain, and by analogy with sarcKATP we proposed SUR2A-55 as a candidate regulatory subunit of mitoKATP. Although SUR2A-55 lacks the first nucleotide binding domain (NBD) and 2 transmembrane domains (TMD), it has a hybrid TMD and retains the second NBD. It resembles a hemi-ABC transporter suggesting it could multimerize to function as a regulatory subunit. A putative mitochondrial targeting signal in the N-terminal domain of SUR2A-55 was removed by truncation and when co-expressed with Kir6.1 and Kir6.2 it targeted to the plasma membrane and yielded KATP currents. Single channel conductance, mean open time, and burst open time of SUR2A-55 based KATP was similar to the full-length SUR2A based KATP. However, the SUR2A-55 KATP were 70-fold less sensitive to block by ATP, and twice as resistant to intracellular Ca (2+) inhibition compared with the SUR2A KATP, and were markedly insensitive to KATP drugs, pinacidil, diazoxide, and glybenclamide. These results suggest that the SUR2A-55 based channels would tend to be open under physiological conditions and in ischemia, and could account for cardiac and mitochondrial phenotypes protective for ischemia.
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Affiliation(s)
- Nitin T Aggarwal
- Department of Medicine; University of Wisconsin; Madison, WI USA
| | - Nian-Qing Shi
- Department of Medicine; University of Wisconsin; Madison, WI USA
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26
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Neuroprotective role of ATP-sensitive potassium channels in cerebral ischemia. Acta Pharmacol Sin 2013; 34:24-32. [PMID: 23123646 DOI: 10.1038/aps.2012.138] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
ATP-sensitive potassium (K(ATP)) channels are weak, inward rectifiers that couple metabolic status to cell membrane electrical activity, thus modulating many cellular functions. An increase in the ADP/ATP ratio opens K(ATP) channels, leading to membrane hyperpolarization. K(ATP) channels are ubiquitously expressed in neurons located in different regions of the brain, including the hippocampus and cortex. Brief hypoxia triggers membrane hyperpolarization in these central neurons. In vivo animal studies confirmed that knocking out the Kir6.2 subunit of the K(ATP) channels increases ischemic infarction, and overexpression of the Kir6.2 subunit reduces neuronal injury from ischemic insults. These findings provide the basis for a practical strategy whereby activation of endogenous K(ATP) channels reduces cellular damage resulting from cerebral ischemic stroke. K(ATP) channel modulators may prove to be clinically useful as part of a combination therapy for stroke management in the future.
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27
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Sierra A, Zhu Z, Sapay N, Sharotri V, Kline CF, Luczak ED, Subbotina E, Sivaprasadarao A, Snyder PM, Mohler PJ, Anderson ME, Vivaudou M, Zingman LV, Hodgson-Zingman DM. Regulation of cardiac ATP-sensitive potassium channel surface expression by calcium/calmodulin-dependent protein kinase II. J Biol Chem 2012; 288:1568-81. [PMID: 23223335 DOI: 10.1074/jbc.m112.429548] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Cardiac ATP-sensitive potassium (K(ATP)) channels are key sensors and effectors of the metabolic status of cardiomyocytes. Alteration in their expression impacts their effectiveness in maintaining cellular energy homeostasis and resistance to injury. We sought to determine how activation of calcium/calmodulin-dependent protein kinase II (CaMKII), a central regulator of calcium signaling, translates into reduced membrane expression and current capacity of cardiac K(ATP) channels. We used real-time monitoring of K(ATP) channel current density, immunohistochemistry, and biotinylation studies in isolated hearts and cardiomyocytes from wild-type and transgenic mice as well as HEK cells expressing wild-type and mutant K(ATP) channel subunits to track the dynamics of K(ATP) channel surface expression. Results showed that activation of CaMKII triggered dynamin-dependent internalization of K(ATP) channels. This process required phosphorylation of threonine at 180 and 224 and an intact (330)YSKF(333) endocytosis motif of the K(ATP) channel Kir6.2 pore-forming subunit. A molecular model of the μ2 subunit of the endocytosis adaptor protein, AP2, complexed with Kir6.2 predicted that μ2 docks by interaction with (330)YSKF(333) and Thr-180 on one and Thr-224 on the adjacent Kir6.2 subunit. Phosphorylation of Thr-180 and Thr-224 would favor interactions with the corresponding arginine- and lysine-rich loops on μ2. We concluded that calcium-dependent activation of CaMKII results in phosphorylation of Kir6.2, which promotes endocytosis of cardiac K(ATP) channel subunits. This mechanism couples the surface expression of cardiac K(ATP) channels with calcium signaling and reveals new targets to improve cardiac energy efficiency and stress resistance.
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Affiliation(s)
- Ana Sierra
- Department of Internal Medicine, University of Iowa, Carver College of Medicine, Iowa City, Iowa 52242, USA
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28
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López-Alonso JP, de Araujo ED, Kanelis V. NMR and fluorescence studies of drug binding to the first nucleotide binding domain of SUR2A. Biochemistry 2012; 51:9211-22. [PMID: 23078514 DOI: 10.1021/bi301019e] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
ATP sensitive potassium (K(ATP)) channels are composed of four copies of a pore-forming inward rectifying potassium channel (Kir6.1 or Kir6.2) and four copies of a sulfonylurea receptor (SUR1, SUR2A, or SUR2B) that surround the pore. SUR proteins are members of the ATP-binding cassette (ABC) superfamily of proteins. Binding of MgATP at the SUR nucleotide binding domains (NBDs) results in NBD dimerization, and hydrolysis of MgATP at the NBDs leads to channel opening. The SUR proteins also mediate interactions with K(ATP) channel openers (KCOs) that activate the channel, with KCO binding and/or activation involving residues in the transmembrane helices and cytoplasmic loops of the SUR proteins. Because the cytoplasmic loops make extensive interactions with the NBDs, we hypothesized that the NBDs may also be involved in KCO binding. Here, we report nuclear magnetic resonance (NMR) spectroscopy studies that demonstrate a specific interaction of the KCO pinacidil with the first nucleotide binding domain (NBD1) from SUR2A, the regulatory SUR protein in cardiac K(ATP) channels. Intrinsic tryptophan fluorescence titrations also demonstrate binding of pinacidil to SUR2A NBD1, and fluorescent nucleotide binding studies show that pinacidil binding increases the affinity of SUR2A NBD1 for ATP. In contrast, the KCO diazoxide does not interact with SUR2A NBD1 under the same conditions. NMR relaxation experiments and size exclusion chromatography indicate that SUR2A NBD1 is monomeric under the conditions used in drug binding studies. These studies identify additional binding sites for commonly used KCOs and provide a foundation for testing binding of drugs to the SUR NBDs.
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Affiliation(s)
- Jorge P López-Alonso
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Road, Mississauga, Ontario, Canada L5L 1C6
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29
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Ortiz D, Voyvodic P, Gossack L, Quast U, Bryan J. Two neonatal diabetes mutations on transmembrane helix 15 of SUR1 increase affinity for ATP and ADP at nucleotide binding domain 2. J Biol Chem 2012; 287:17985-95. [PMID: 22451668 DOI: 10.1074/jbc.m112.349019] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
K(ATP) channels, (SUR1/Kir6.2)(4) (sulfonylurea receptor type 1/potassium inward rectifier type 6.2) respond to the metabolic state of pancreatic β-cells, modulating membrane potential and insulin exocytosis. Mutations in both subunits cause neonatal diabetes by overactivating the pore. Hyperactive channels fail to close appropriately with increased glucose metabolism; thus, β-cell hyperpolarization limits insulin release. K(ATP) channels are inhibited by ATP binding to the Kir6.2 pore and stimulated, via an uncertain mechanism, by magnesium nucleotides at SUR1. Glibenclamide (GBC), a sulfonylurea, was used as a conformational probe to compare nucleotide action on wild type versus Q1178R and R1182Q SUR1 mutants. GBC binds with high affinity to aporeceptors, presumably in the inward facing ATP-binding cassette configuration; MgATP reduces binding affinity via a shift to the outward facing conformation. To determine nucleotide affinities under equilibrium, non-hydrolytic conditions, Mg(2+) was eliminated. A four-state equilibrium model describes the allosteric linkage. The K(D) for ATP(4-) is ~1 versus 12 mM, Q1178R versus wild type, respectively. The linkage constant is ~10, implying that outward facing conformations bind GBC with a lower affinity, 9-10 nM for Q1178R. Thus, nucleotides cannot completely inhibit GBC binding. Binding of channel openers is reported to require ATP hydrolysis, but diazoxide, a SUR1-selective agonist, concentration-dependently augments ATP(4-) action. An eight-state model describes linkage between diazoxide and ATP(4-) binding; diazoxide markedly increases the affinity of Q1178R for ATP(4-) and ATP(4-) augments diazoxide binding. NBD2, but not NBD1, has a higher affinity for ATP (and ADP) in mutant versus wild type (with or without Mg(2+)). Thus, the mutants spend more time in nucleotide-bound conformations, with reduced affinity for GBC, that activate the pore.
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Affiliation(s)
- David Ortiz
- Graduate Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston, Texas 77030, USA
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30
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Winkler M, Kühner P, Russ U, Ortiz D, Bryan J, Quast U. Role of the amino-terminal transmembrane domain of sulfonylurea receptor SUR2B for coupling to KIR6.2, ligand binding, and oligomerization. Naunyn Schmiedebergs Arch Pharmacol 2011; 385:287-98. [DOI: 10.1007/s00210-011-0708-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Accepted: 10/24/2011] [Indexed: 01/11/2023]
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31
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Eicosapentaenoic acid reduces ischemic ventricular fibrillation via altering monophasic action potential in pigs. J Mol Cell Cardiol 2011; 51:329-36. [DOI: 10.1016/j.yjmcc.2011.05.018] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Revised: 05/13/2011] [Accepted: 05/23/2011] [Indexed: 11/22/2022]
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32
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Quan Y, Barszczyk A, Feng ZP, Sun HS. Current understanding of K ATP channels in neonatal diseases: focus on insulin secretion disorders. Acta Pharmacol Sin 2011; 32:765-80. [PMID: 21602835 PMCID: PMC4009965 DOI: 10.1038/aps.2011.57] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2011] [Accepted: 04/13/2011] [Indexed: 12/25/2022] Open
Abstract
ATP-sensitive potassium (K(ATP)) channels are cell metabolic sensors that couple cell metabolic status to electric activity, thus regulating many cellular functions. In pancreatic beta cells, K(ATP) channels modulate insulin secretion in response to fluctuations in plasma glucose level, and play an important role in glucose homeostasis. Recent studies show that gain-of-function and loss-of-function mutations in K(ATP) channel subunits cause neonatal diabetes mellitus and congenital hyperinsulinism respectively. These findings lead to significant changes in the diagnosis and treatment for neonatal insulin secretion disorders. This review describes the physiological and pathophysiological functions of K(ATP) channels in glucose homeostasis, their specific roles in neonatal diabetes mellitus and congenital hyperinsulinism, as well as future perspectives of K(ATP) channels in neonatal diseases.
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Affiliation(s)
- Yi Quan
- Departments of Physiology, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada, M5S 1A8
| | - Andrew Barszczyk
- Departments of Physiology, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada, M5S 1A8
| | - Zhong-ping Feng
- Departments of Physiology, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada, M5S 1A8
| | - Hong-shuo Sun
- Departments of Physiology, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada, M5S 1A8
- Departments of Surgery, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada, M5S 1A8
- Departments of Pharmacology, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada, M5S 1A8
- Institute of Medical Science, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada, M5S 1A8
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33
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β2-Adrenergic ion-channel coupled receptors as conformational motion detectors. PLoS One 2011; 6:e18226. [PMID: 21464970 PMCID: PMC3064670 DOI: 10.1371/journal.pone.0018226] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2010] [Accepted: 02/25/2011] [Indexed: 12/14/2022] Open
Abstract
Ion Channel-Coupled Receptors (ICCRs) are artificial proteins comprised of a G protein-coupled receptor and a fused ion channel, engineered to couple channel gating to ligand binding. These novel biological objects have potential use in drug screening and functional characterization, in addition to providing new tools in the synthetic biology repertoire as synthetic K+-selective ligand-gated channels. The ICCR concept was previously validated with fusion proteins between the K+ channel Kir6.2 and muscarinic M2 or dopaminergic D2 receptors. Here, we extend the concept to the distinct, longer β2-adrenergic receptor which, unlike M2 and D2 receptors, displayed barely detectable surface expression in our Xenopus oocyte expression system and did not couple to Kir6.2 when unmodified. Here, we show that a Kir6.2-binding protein, the N-terminal transmembrane domain of the sulfonylurea receptor, can greatly increase plasma membrane expression of β2 constructs. We then demonstrate how engineering of both receptor and channel can produce β2-Kir6.2 ICCRs. Specifically, removal of 62–72 residues from the cytoplasmic C-terminus of the receptor was required to enable coupling, suggesting that ligand-dependent conformational changes do not efficiently propagate to the distal C-terminus. Characterization of the β2 ICCRs demonstrated that full and partial agonists had the same coupling efficacy, that an inverse agonist had no effect and that the stabilizing mutation E122 W reduced agonist-induced coupling efficacy without affecting affinity. Because the ICCRs are expected to report motions of the receptor C-terminus, these results provide novel insights into the conformational dynamics of the β2 receptor.
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34
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Bessadok A, Garcia E, Jacquet H, Martin S, Garrigues A, Loiseau N, André F, Orlowski S, Vivaudou M. Recognition of sulfonylurea receptor (ABCC8/9) ligands by the multidrug resistance transporter P-glycoprotein (ABCB1): functional similarities based on common structural features between two multispecific ABC proteins. J Biol Chem 2010; 286:3552-69. [PMID: 21098040 DOI: 10.1074/jbc.m110.155200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
ATP-sensitive K(+) (K(ATP)) channels are the target of a number of pharmacological agents, blockers like hypoglycemic sulfonylureas and openers like the hypotensive cromakalim and diazoxide. These agents act on the channel regulatory subunit, the sulfonylurea receptor (SUR), which is an ABC protein with homologies to P-glycoprotein (P-gp). P-gp is a multidrug transporter expressed in tumor cells and in some healthy tissues. Because these two ABC proteins both exhibit multispecific recognition properties, we have tested whether SUR ligands could be substrates of P-gp. Interaction with P-gp was assayed by monitoring ATPase activity of P-gp-enriched vesicles. The blockers glibenclamide, tolbutamide, and meglitinide increased ATPase activity, with a rank order of potencies that correlated with their capacity to block K(ATP) channels. P-gp ATPase activity was also increased by the openers SR47063 (a cromakalim analog), P1075 (a pinacidil analog), and diazoxide. Thus, these molecules bind to P-gp (although with lower affinities than for SUR) and are possibly transported by P-gp. Competition experiments among these molecules as well as with typical P-gp substrates revealed a structural similarity between drug binding domains in the two proteins. To rationalize the observed data, we addressed the molecular features of these proteins and compared structural models, computerized by homology from the recently solved structures of murine P-gp and bacterial ABC transporters MsbA and Sav1866. Considering the various residues experimentally assigned to be involved in drug binding, we uncovered several hot spots, which organized spatially in two main binding domains, selective for SR47063 and for glibenclamide, in matching regions of both P-gp and SUR.
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Affiliation(s)
- Anis Bessadok
- Service de Bioénergétique, Biologie Structurale et Mécanismes, URA 2096 CNRS, iBiTec-S, Commissariat à l'Energie Atomique-Saclay, 91191 Gif-sur-Yvette Cedex, France
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Flagg TP, Enkvetchakul D, Koster JC, Nichols CG. Muscle KATP channels: recent insights to energy sensing and myoprotection. Physiol Rev 2010; 90:799-829. [PMID: 20664073 DOI: 10.1152/physrev.00027.2009] [Citation(s) in RCA: 202] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
ATP-sensitive potassium (K(ATP)) channels are present in the surface and internal membranes of cardiac, skeletal, and smooth muscle cells and provide a unique feedback between muscle cell metabolism and electrical activity. In so doing, they can play an important role in the control of contractility, particularly when cellular energetics are compromised, protecting the tissue against calcium overload and fiber damage, but the cost of this protection may be enhanced arrhythmic activity. Generated as complexes of Kir6.1 or Kir6.2 pore-forming subunits with regulatory sulfonylurea receptor subunits, SUR1 or SUR2, the differential assembly of K(ATP) channels in different tissues gives rise to tissue-specific physiological and pharmacological regulation, and hence to the tissue-specific pharmacological control of contractility. The last 10 years have provided insights into the regulation and role of muscle K(ATP) channels, in large part driven by studies of mice in which the protein determinants of channel activity have been deleted or modified. As yet, few human diseases have been correlated with altered muscle K(ATP) activity, but genetically modified animals give important insights to likely pathological roles of aberrant channel activity in different muscle types.
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Affiliation(s)
- Thomas P Flagg
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
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Tei A, Nejime N, Tada Y, Kagota S, Tanabe Y, Hashimoto M, Shinozuka K. Effects of nicorandil on sympathetic neurotransmission in rat caudal artery. Clin Exp Pharmacol Physiol 2010; 37:619-23. [PMID: 20132237 DOI: 10.1111/j.1440-1681.2010.05366.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
1. We examined the effects of nicorandil, an ATP-sensitive potassium (K(ATP)) channel opener and nitric oxide donor, on the release of noradrenaline from vascular sympathetic nerves. This effect was compared to the effect on vascular smooth muscle. 2. Caudal artery preparations from Wistar rats were electrically stimulated (1 Hz, 0.5-ms duration) and noradrenaline release in the artery was detected using an high-pressure liquid chromatography-electrochemical detection technique. The pharmacological properties of the prejunctional effect of nicorandil were determined using the nonselective K(ATP) channel blocker glibenclamide, the pancreatic beta-cell and brain-type K(ATP) channel blocker tolbutamide, and the smooth muscle-type K(ATP) channel blocker PNU-37883A. 3. Nicorandil inhibited the electrical stimulation-evoked noradrenaline release in a concentration-dependent manner. This inhibitory effect was abolished by 1 micromol/L glibenclamide and 10 micromol/L tolbutamide, but was not affected by 10 micromol/L PNU-37883A or 0.3 micromol/L ODQ. Nicorandil did not affect the noradrenaline transporter uptake 1 in the adrenergic nerve terminals. 4. Nicorandil produced a relaxation response in a concentration-dependent manner in the caudal artery pre-contracted with 0.3 micromol/L noradrenaline. This relaxation response was significantly diminished in the presence of 1 micromol/L glibenclamide, 10 micromol/L PNU-37883A and 0.3 micromol/L ODQ but not by 10 micromol/L tolbutamide. 5. These findings suggest that nicorandil inhibits noradrenaline release via the K(ATP) channels of sympathetic nerves. These channels may be pharmacologically different from those of vascular smooth muscle.
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Affiliation(s)
- Ami Tei
- Department of Pharmacology and Pharmaceutics, School of Pharmaceutical Sciences, Mukogawa Women's University, Nishinomiya 663-8179, Japan
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Hibino H, Inanobe A, Furutani K, Murakami S, Findlay I, Kurachi Y. Inwardly rectifying potassium channels: their structure, function, and physiological roles. Physiol Rev 2010; 90:291-366. [PMID: 20086079 DOI: 10.1152/physrev.00021.2009] [Citation(s) in RCA: 1074] [Impact Index Per Article: 76.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Inwardly rectifying K(+) (Kir) channels allow K(+) to move more easily into rather than out of the cell. They have diverse physiological functions depending on their type and their location. There are seven Kir channel subfamilies that can be classified into four functional groups: classical Kir channels (Kir2.x) are constitutively active, G protein-gated Kir channels (Kir3.x) are regulated by G protein-coupled receptors, ATP-sensitive K(+) channels (Kir6.x) are tightly linked to cellular metabolism, and K(+) transport channels (Kir1.x, Kir4.x, Kir5.x, and Kir7.x). Inward rectification results from pore block by intracellular substances such as Mg(2+) and polyamines. Kir channel activity can be modulated by ions, phospholipids, and binding proteins. The basic building block of a Kir channel is made up of two transmembrane helices with cytoplasmic NH(2) and COOH termini and an extracellular loop which folds back to form the pore-lining ion selectivity filter. In vivo, functional Kir channels are composed of four such subunits which are either homo- or heterotetramers. Gene targeting and genetic analysis have linked Kir channel dysfunction to diverse pathologies. The crystal structure of different Kir channels is opening the way to understanding the structure-function relationships of this simple but diverse ion channel family.
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Affiliation(s)
- Hiroshi Hibino
- Department of Pharmacology, Graduate School of Medicine and The Center for Advanced Medical Engineering and Informatics, Osaka University, Osaka 565-0871, Japan
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Li GR, Dong MQ. Pharmacology of Cardiac Potassium Channels. CARDIOVASCULAR PHARMACOLOGY - HEART AND CIRCULATION 2010; 59:93-134. [DOI: 10.1016/s1054-3589(10)59004-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Hosy E, Dupuis JP, Vivaudou M. Impact of disease-causing SUR1 mutations on the KATP channel subunit interface probed with a rhodamine protection assay. J Biol Chem 2009; 285:3084-91. [PMID: 19933268 DOI: 10.1074/jbc.m109.043307] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The function of the ATP-sensitive potassium (K(ATP)) channel relies on the proper coupling between its two subunits: the pore-forming Kir6.2 and the regulator SUR. The conformation of the interface between these two subunits can be monitored using a rhodamine 123 (Rho) protection assay because Rho blocks Kir6.2 with an efficiency that depends on the relative position of transmembrane domain (TMD) 0 of the associated SUR (Hosy, E., Dérand, R., Revilloud, J., and Vivaudou, M. (2007) J. Physiol. 582, 27-39). Here we find that the natural and synthetic K(ATP) channel activators MgADP, zinc, and SR47063 induced a Rho-insensitive conformation. The activating mutation F132L in SUR1, which causes neonatal diabetes, also rendered the channel resistant to Rho block, suggesting that it stabilized an activated conformation by uncoupling TMD0 from the rest of SUR1. At a nearby residue, the SUR1 mutation E128K impairs trafficking, thereby reducing surface expression and causing hyperinsulinism. To augment channel density at the plasma membrane to investigate the effect of mutating this residue on channel function, we introduced the milder mutation E126A at the matching residue of SUR2A. Mutation E126A imposed a hypersensitive Rho phenotype indicative of a functional uncoupling between TMD0 and Kir6.2. These results suggest that the TMD0-Kir6.2 interface is mobile and that the gating modes of Kir6.2 correlate with distinct positions of TMD0. They further demonstrate that the second intracellular loop of SUR, which contains the two residues studied here, is a key structural element of the TMD0-Kir6.2 interface.
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Affiliation(s)
- Eric Hosy
- Institut de Biologie Structurale (CEA, CNRS, UJF), Laboratoire des Protéines Membranaires, 41 Rue Jules Horowitz, 38027 Grenoble, France
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Remedi MS, Koster JC. K(ATP) channelopathies in the pancreas. Pflugers Arch 2009; 460:307-20. [PMID: 19921246 DOI: 10.1007/s00424-009-0756-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2009] [Revised: 10/20/2009] [Accepted: 10/23/2009] [Indexed: 12/14/2022]
Abstract
Adenosine-triphosphate-sensitive potassium channels (KATP) are regulated by adenosine nucleotides, and, thereby, couple cellular metabolism with electrical activity in multiple tissues including the pancreatic beta-cell. The critical involvement of KATP in insulin secretion is confirmed by the demonstration that inactivating and activating mutations in KATP underlie persistent hyperinsulinemia and neonatal diabetes mellitus, respectively, in both animal models and humans. In addition, a common variant in KATP represents a risk factor in the etiology of type 2 diabetes. This review focuses on the mechanistic basis by which KATP mutations underlie insulin secretory disorders and the implications of these findings for successful clinical intervention.
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Affiliation(s)
- Maria S Remedi
- Department of Cell Biology and Physiology, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA.
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Ackermann S, Hiller S, Osswald H, Lösle M, Grenz A, Hambrock A. 17beta-Estradiol modulates apoptosis in pancreatic beta-cells by specific involvement of the sulfonylurea receptor (SUR) isoform SUR1. J Biol Chem 2008; 284:4905-13. [PMID: 19095654 DOI: 10.1074/jbc.m807638200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Apoptosis of pancreatic beta-cells is an important factor in the pathophysiology of diabetes. Previously, we have shown that the "phytoestrogen" resveratrol can induce beta-cell apoptosis dependent on the expression of sulfonylurea receptor (SUR) 1, the regulatory subunit of pancreatic ATP-sensitive K(+) channels. Here, we investigate whether 17beta-estradiol also influences beta-cell apoptosis in a SUR1-dependent manner. Therefore, islets from wild type or SUR1 knock-out mice, clonal beta-cells, or HEK293 cells expressing different SUR forms were treated with 17beta-estradiol or estrone. Different apoptotic parameters were determined and estrogen binding to SUR was analyzed. In murine islets, 17beta-estradiol treatment resulted in significant apoptotic changes, which in their nature (either apoptotic or anti-apoptotic) were dependent on the age of the animal. These effects were not observed in SUR1 knock-out mice. Furthermore, 17beta-estradiol, which specifically binds to SUR, induced enhanced apoptosis in SUR1-expressing HEK293 cells and clonal beta-cells, whereas apoptosis in recombinant cells expressing SUR2A or SUR2B (cardiac or vascular SUR-isoforms) or sham-transfected control cells was significantly lower. The apoptotic potency of 17beta-estradiol was much higher than that of resveratrol or estrone. SUR1-specific 17beta-estradiol-induced apoptosis was either abolished by the mutation M1289T in transmembrane helix 17 of SUR1 or clearly enhanced by two mutations in nucleotide binding fold 2 (R1379C, R1379L). In conclusion, 17beta-estradiol treatment modulates beta-cell apoptosis under specific involvement of SUR1 in an age-dependent manner. 17beta-Estradiol-induced apoptosis can be influenced by certain SUR1 mutations. These findings may contribute to the understanding of pathophysiological changes in beta-cell mass and could, for instance, provide interesting aspects concerning the etiology of gestational diabetes.
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Affiliation(s)
- Stefanie Ackermann
- Department of Pharmacology and Toxicology, Medical Faculty, University of Tübingen, Wilhelmstrasse 56, D-72074 Tübingen, Germany
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Garlid KD, Costa ADT, Quinlan CL, Pierre SV, Dos Santos P. Cardioprotective signaling to mitochondria. J Mol Cell Cardiol 2008; 46:858-66. [PMID: 19118560 DOI: 10.1016/j.yjmcc.2008.11.019] [Citation(s) in RCA: 156] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2008] [Revised: 11/07/2008] [Accepted: 11/26/2008] [Indexed: 01/05/2023]
Abstract
Mitochondria are central players in the pathophysiology of ischemia-reperfusion. Activation of plasma membrane G-coupled receptors or the Na,K-ATPase triggers cytosolic signaling pathways that result in cardioprotection. Our working hypothesis is that the occupied receptors migrate to caveolae, where signaling enzymes are scaffolded into signalosomes that bud off the plasma membrane and migrate to mitochondria. The signalosome-mitochondria interaction then initiates intramitochondrial signaling by opening the mitochondrial ATP-sensitive K(+) channel (mitoK(ATP)). MitoK(ATP) opening causes an increase in ROS production, which activates mitochondrial protein kinase C epsilon (PKCvarepsilon), which inhibits the mitochondrial permeability transition (MPT), thus decreasing cell death. We review the experimental findings that bear on these hypotheses and other modes of protection involving mitochondria.
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Affiliation(s)
- Keith D Garlid
- Department of Biology, Portland State University, Portland, OR 97201-0751, USA.
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Moreau CJ, Dupuis JP, Revilloud J, Arumugam K, Vivaudou M. Coupling ion channels to receptors for biomolecule sensing. NATURE NANOTECHNOLOGY 2008; 3:620-625. [PMID: 18839002 DOI: 10.1038/nnano.2008.242] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2008] [Accepted: 07/24/2008] [Indexed: 05/26/2023]
Abstract
Nanoscale electrical biosensors are promising tools for diagnostics and high-throughput screening systems. The electrical signal allows label-free assays with a high signal-to-noise ratio and fast real-time measurements. The challenge in developing such biosensors lies in functionally connecting a molecule detector to an electrical switch. Advances in this field have relied on synthetic ion-conducting pores and modified ion channels that are not yet suitable for biomolecule screening. Here we report the design and characterization of a novel bioelectric-sensing platform engineered by coupling an ion channel, which serves as the electrical probe, to G-protein-coupled receptors (GPCRs), a family of receptors that detect molecules outside the cell. These ion-channel-coupled receptors may potentially detect a wide range of ligands recognized by natural or altered GPCRs, which are known to be major pharmaceutical targets. This could form a unique platform for label-free drug screening.
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MESH Headings
- Animals
- Biosensing Techniques/methods
- Dopamine D2 Receptor Antagonists
- Drug Evaluation, Preclinical/methods
- Electric Conductivity
- Humans
- Ion Transport/drug effects
- Ligands
- Mice
- Multiprotein Complexes/genetics
- Multiprotein Complexes/metabolism
- Potassium Channels/genetics
- Potassium Channels/metabolism
- Potassium Channels, Inwardly Rectifying/genetics
- Potassium Channels, Inwardly Rectifying/metabolism
- Protein Engineering/methods
- Receptor, Muscarinic M2/agonists
- Receptor, Muscarinic M2/antagonists & inhibitors
- Receptor, Muscarinic M2/genetics
- Receptor, Muscarinic M2/metabolism
- Receptors, Dopamine D2/agonists
- Receptors, Dopamine D2/genetics
- Receptors, Dopamine D2/metabolism
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
- Signal Transduction
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Affiliation(s)
- Christophe J Moreau
- Laboratoire des Protéines Membranaires, Institut de Biologie Structurale (CEA, CNRS, UJF), 41 rue Jules Horowitz, 38027 Grenoble, France
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Costa ADT, Garlid KD. Intramitochondrial signaling: interactions among mitoKATP, PKCepsilon, ROS, and MPT. Am J Physiol Heart Circ Physiol 2008; 295:H874-82. [PMID: 18586884 DOI: 10.1152/ajpheart.01189.2007] [Citation(s) in RCA: 167] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Activation of protein kinase Cepsilon (PKCepsilon), opening of mitochondrial ATP-sensitive K(+) channels (mitoK(ATP)), and increased mitochondrial reactive oxygen species (ROS) are key events in the signaling that underlies cardioprotection. We showed previously that mitoK(ATP) is opened by activation of a mitochondrial PKCepsilon, designated PKCepsilon1, that is closely associated with mitoK(ATP). mitoK(ATP) opening then causes an increase in ROS production by complex I of the respiratory chain. This ROS activates a second pool of PKCepsilon, designated PKCepsilon2, which inhibits the mitochondrial permeability transition (MPT). In the present study, we measured mitoK(ATP)-dependent changes in mitochondrial matrix volume to further investigate the relationships among PKCepsilon, mitoK(ATP), ROS, and MPT. We present evidence that 1) mitoK(ATP) can be opened by H(2)O(2) and nitric oxide (NO) and that these effects are mediated by PKCepsilon1 and not by direct actions on mitoK(ATP), 2) superoxide has no effect on mitoK(ATP) opening, 3) exogenous H(2)O(2) or NO also inhibits MPT opening, and both compounds do so independently of mitoK(ATP) activity via activation of PKCepsilon2, 4) mitoK(ATP) opening induced by PKG, phorbol ester, or diazoxide is not mediated by ROS, and 5) mitoK(ATP)-generated ROS activates PKCepsilon1 and induces phosphorylation-dependent mitoK(ATP) opening in vitro and in vivo. Thus mitoK(ATP)-dependent mitoK(ATP) opening constitutes a positive feedback loop capable of maintaining the channel open after the stimulus is no longer present. This feedback pathway may be responsible for the lasting protective effect of preconditioning, colloquially known as the memory effect.
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Affiliation(s)
- Alexandre D T Costa
- Dept. of Biology, Portland State Univ., PO Box 751, Portland, OR 97201-0751, USA
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Karger AB, Park S, Reyes S, Bienengraeber M, Dyer RB, Terzic A, Alekseev AE. Role for SUR2A ED domain in allosteric coupling within the K(ATP) channel complex. ACTA ACUST UNITED AC 2008; 131:185-96. [PMID: 18299394 PMCID: PMC2248718 DOI: 10.1085/jgp.200709852] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Allosteric regulation of heteromultimeric ATP-sensitive potassium (KATP) channels is unique among protein systems as it implies transmission of ligand-induced structural adaptation at the regulatory SUR subunit, a member of ATP-binding cassette ABCC family, to the distinct pore-forming K+ (Kir6.x) channel module. Cooperative interaction between nucleotide binding domains (NBDs) of SUR is a prerequisite for KATP channel gating, yet pathways of allosteric intersubunit communication remain uncertain. Here, we analyzed the role of the ED domain, a stretch of 15 negatively charged aspartate/glutamate amino acid residues (948–962) of the SUR2A isoform, in the regulation of cardiac KATP channels. Disruption of the ED domain impeded cooperative NBDs interaction and interrupted the regulation of KATP channel complexes by MgADP, potassium channel openers, and sulfonylurea drugs. Thus, the ED domain is a structural component of the allosteric pathway within the KATP channel complex integrating transduction of diverse nucleotide-dependent states in the regulatory SUR subunit to the open/closed states of the K+-conducting channel pore.
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Affiliation(s)
- Amy B Karger
- Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic, Rochester, MN 55905, USA
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Farzaneh T, Tinker A. Differences in the mechanism of metabolic regulation of ATP-sensitive K+ channels containing Kir6.1 and Kir6.2 subunits. Cardiovasc Res 2008; 79:621-31. [PMID: 18522960 DOI: 10.1093/cvr/cvn138] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
AIMS ATP sensitive K(+) channels (K(ATP)) sense adenine nucleotide concentrations and thus couple the metabolic state of the cell to membrane potential. The hetero-octameric complex of a sulphonylurea receptor (SUR2B) and an inwardly rectifying K(+) channel (Kir6.1) and the corresponding native channel in smooth muscle are relatively insensitive to variations in intracellular ATP. Activation of these channels in blood vessels during hypoxia/ischaemia is thought to be mediated via hormonal regulation such as cellular adenosine release or the release of mediators from the endothelium. In contrast, intracellular ATP prominently inhibits Kir6.2 containing complexes, such as those present in cardiac myocytes. Thus, we investigated differences in the mechanism of metabolic regulation of Kir6.1 and Kir6.2 containing K(ATP) channels. METHODS AND RESULTS We have heterologously expressed K(ATP) channel subunits in HEK293 and CHO cells and studied their function using (86)Rb efflux and patch clamping. We show that rodent Kir6.1/SUR2B has direct intrinsic metabolic sensitivity independent of any regulation by protein kinase A. In contrast to Kir6.2 containing complexes, this was not endowed by the ATP sensitivity of the pore forming subunit but was instead a property of the SUR2B subunit. Mutagenesis of key residues within the nucleotide-binding domains (NBD) implicated both domains in governing the metabolic sensitivity. CONCLUSION Kir6.1\SUR2B has intrinsic sensitivity to metabolism endowed by the likely processing of adenine nucleotides at the NBD of SUR2B.
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Affiliation(s)
- Tabasum Farzaneh
- BHF Laboratories, Department of Medicine, The Rayne Institute, University College London, Room 107, 5 University Street, London WC1E 6JJ, UK
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47
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Dupuis JP, Revilloud J, Moreau CJ, Vivaudou M. Three C-terminal residues from the sulphonylurea receptor contribute to the functional coupling between the K(ATP) channel subunits SUR2A and Kir6.2. J Physiol 2008; 586:3075-85. [PMID: 18450778 DOI: 10.1113/jphysiol.2008.152744] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Cardiac ATP-sensitive potassium (K(ATP)) channels are metabolic sensors formed by the association of the inward rectifier potassium channel Kir6.2 and the sulphonylurea receptor SUR2A. SUR2A adjusts channel gating as a function of intracellular ATP and ADP and is the target of pharmaceutical openers and blockers which, respectively, up- and down-regulate Kir6.2. In an effort to understand how effector binding to SUR2A translates into Kir6.2 gating modulation, we examined the role of a 65-residue SUR2A fragment linking transmembrane domain TMD2 and nucleotide-binding domain NBD2 that has been shown to interact with Kir6.2. This fragment of SUR2A was replaced by the equivalent residues of its close homologue, the multidrug resistance protein MRP1. The chimeric construct was expressed in Xenopus oocytes and characterized using the patch-clamp technique. We found that activation by MgADP and synthetic openers was greatly attenuated although apparent affinities were unchanged. Further chimeragenetic and mutagenetic studies showed that mutation of three residues, E1305, I1310 and L1313 (rat numbering), was sufficient to confer this defective phenotype. The same mutations had no effects on channel block by the sulphonylurea glibenclamide or by ATP, suggesting a role for these residues in activatory--but not inhibitory--transduction processes. These results indicate that, within the K(ATP) channel complex, the proximal C-terminal of SUR2A is a critical link between ligand binding to SUR2A and Kir6.2 up-regulation.
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Affiliation(s)
- Julien P Dupuis
- Institut de Biologie Structurale, UMR5075 CEA-CNRS-University J. Fourier, 41, rue Jules Horowitz, 38027 Grenoble, France
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Cairns BE, Mann MK, Mok E, Dong XD, Svensson P. Diclofenac exerts local anesthetic-like actions on rat masseter muscle afferent fibers. Brain Res 2008; 1194:56-64. [DOI: 10.1016/j.brainres.2007.11.060] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2007] [Revised: 11/26/2007] [Accepted: 11/27/2007] [Indexed: 10/22/2022]
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Guiot Y, Stevens M, Marhfour I, Stiernet P, Mikhailov M, Ashcroft SJH, Rahier J, Henquin JC, Sempoux C. Morphological localisation of sulfonylurea receptor 1 in endocrine cells of human, mouse and rat pancreas. Diabetologia 2007; 50:1889-1899. [PMID: 17593344 DOI: 10.1007/s00125-007-0731-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2007] [Accepted: 05/14/2007] [Indexed: 12/25/2022]
Abstract
AIMS/HYPOTHESIS Sulfonylurea receptor 1 (SUR1) is the regulatory subunit of ATP-sensitive K channels in beta cells. Morphological methods (immunohistochemistry and sulfonylurea binding) were used to establish the cellular and subcellular location of SUR1 in human and rodent islets. RESULTS In the human, mouse and rat pancreas, all endocrine cells of the islets were immunolabelled with an anti-SUR1 antibody, whereas tissues containing SUR2 were consistently negative, as were those from Sur1 (also known as Abcc8)(-/-) mice. In beta cells of the three species, the plasma membrane was distinctly stained, but SUR1 was mainly present over the cytoplasm, with an intensity that varied between cells. Electron microscopy showed that SUR1 was immunolocalised in insulin, glucagon and somatostatin granules. In rat beta cells degranulated by in vivo treatment with glibenclamide (known as glyburide in the USA and Canada), the insulin and SUR1 staining intensity was similarly decreased by approximately 45%, whereas SUR1 staining was not changed in non-beta cells. In all islet cells, binding of glibenclamide labelled with fluorescent dipyrromethane boron difluoride (BODIPY-FL) was punctate over the cytoplasm, compatible with the labelling of endocrine granules. A faint labelling persisted in Sur1 (-/-) mice, but it was not different from that obtained with BODIPY-FL alone used as negative control. CONCLUSIONS/INTERPRETATION Our study immunolocalised SUR1 in alpha, beta and delta cells of human, mouse and rat islets, and for the first time visualised it in the plasma membrane. We also show that SUR1 is abundant in endocrine granules, where its function remains to be established. No specific sulfonylurea-binding sites other than SUR1 are identified in islet cells by the glibenclamide-BODIPY-FL technique.
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Affiliation(s)
- Y Guiot
- Department of Pathology, Faculty of Medicine, University of Louvain, B-1200, Brussels, Belgium.
| | - M Stevens
- Department of Pathology, Faculty of Medicine, University of Louvain, B-1200, Brussels, Belgium
| | - I Marhfour
- Department of Pathology, Faculty of Medicine, University of Louvain, B-1200, Brussels, Belgium
| | - P Stiernet
- Endocrinology Unit and Metabolism, Faculty of Medicine, University of Louvain, UCL5530, Brussels, Belgium
| | - M Mikhailov
- Physiology Laboratory, University of Oxford, Oxford, UK
| | - S J H Ashcroft
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, UK
| | - J Rahier
- Department of Pathology, Faculty of Medicine, University of Louvain, B-1200, Brussels, Belgium
| | - J-C Henquin
- Endocrinology Unit and Metabolism, Faculty of Medicine, University of Louvain, UCL5530, Brussels, Belgium
| | - C Sempoux
- Department of Pathology, Faculty of Medicine, University of Louvain, B-1200, Brussels, Belgium
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Zingman LV, Alekseev AE, Hodgson-Zingman DM, Terzic A. ATP-sensitive potassium channels: metabolic sensing and cardioprotection. J Appl Physiol (1985) 2007; 103:1888-93. [PMID: 17641217 DOI: 10.1152/japplphysiol.00747.2007] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The cardiovascular system operates under a wide scale of demands, ranging from conditions of rest to extreme stress. How the heart muscle matches rates of ATP production with utilization is an area of active investigation. ATP-sensitive potassium (K(ATP)) channels serve a critical role in the orchestration of myocardial energetic well-being. K(ATP) channel heteromultimers consist of inwardly-rectifying K(+) channel 6.2 and ATP-binding cassette sulfonylurea receptor 2A that translates local ATP/ADP levels, set by ATPases and phosphotransfer reactions, to the channel pore function. In cells in which the mobility of metabolites between intracellular microdomains is limited, coupling of phosphotransfer pathways with K(ATP) channels permits a high-fidelity transduction of nucleotide fluxes into changes in membrane excitability, matching energy demands with metabolic resources. This K(ATP) channel-dependent optimization of cardiac action potential duration preserves cellular energy balance at varying workloads. Mutations of K(ATP) channels result in disruption of the nucleotide signaling network and generate a stress-vulnerable phenotype with excessive susceptibility to injury, development of cardiomyopathy, and arrhythmia. Solving the mechanisms underlying the integration of K(ATP) channels into the cellular energy network will advance the understanding of endogenous cardioprotection and the development of strategies for the management of cardiovascular injury and disease progression.
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Affiliation(s)
- L V Zingman
- Univ. of Iowa, Carver College of Medicine, 285 Newton Rd., CBRB2296, Iowa City, IA 52242, USA.
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