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Renigunta V, Fischer T, Zuzarte M, Kling S, Zou X, Siebert K, Limberg MM, Rinné S, Decher N, Schlichthörl G, Daut J. Cooperative endocytosis of the endosomal SNARE protein syntaxin-8 and the potassium channel TASK-1. Mol Biol Cell 2014; 25:1877-91. [PMID: 24743596 PMCID: PMC4055267 DOI: 10.1091/mbc.e13-10-0592] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
SNARE proteins can have functions unrelated to membrane fusion. The unassembled form of the SNARE protein syntaxin-8 interacts with the K+ channel TASK-1; both proteins are internalized via clathrin-mediated endocytosis in a cooperative manner. This is a novel mechanism for the control of endocytosis by cargo proteins. The endosomal SNARE protein syntaxin-8 interacts with the acid-sensitive potassium channel TASK-1. The functional relevance of this interaction was studied by heterologous expression of these proteins (and mutants thereof) in Xenopus oocytes and in mammalian cell lines. Coexpression of syntaxin-8 caused a fourfold reduction in TASK-1 current, a corresponding reduction in the expression of TASK-1 at the cell surface, and a marked increase in the rate of endocytosis of the channel. TASK-1 and syntaxin-8 colocalized in the early endosomal compartment, as indicated by the endosomal markers 2xFYVE and rab5. The stimulatory effect of the SNARE protein on the endocytosis of the channel was abolished when both an endocytosis signal in TASK-1 and an endocytosis signal in syntaxin-8 were mutated. A syntaxin-8 mutant that cannot assemble with other SNARE proteins had virtually the same effect as wild-type syntaxin-8. Total internal reflection fluorescence microscopy showed formation and endocytosis of vesicles containing fluorescence-tagged clathrin, TASK-1, and/or syntaxin-8. Our results suggest that the unassembled form of syntaxin-8 and the potassium channel TASK-1 are internalized via clathrin-mediated endocytosis in a cooperative manner. This implies that syntaxin-8 regulates the endocytosis of TASK-1. Our study supports the idea that endosomal SNARE proteins can have functions unrelated to membrane fusion.
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Affiliation(s)
- Vijay Renigunta
- Institute of Physiology and Pathophysiology, Marburg University, 35037 Marburg, Germany
| | - Thomas Fischer
- Institute of Physiology and Pathophysiology, Marburg University, 35037 Marburg, Germany
| | - Marylou Zuzarte
- Institute of Physiology and Pathophysiology, Marburg University, 35037 Marburg, Germany
| | - Stefan Kling
- Institute of Physiology and Pathophysiology, Marburg University, 35037 Marburg, Germany
| | - Xinle Zou
- Institute of Physiology and Pathophysiology, Marburg University, 35037 Marburg, Germany
| | - Kai Siebert
- Institute of Physiology and Pathophysiology, Marburg University, 35037 Marburg, Germany
| | - Maren M Limberg
- Institute of Physiology and Pathophysiology, Marburg University, 35037 Marburg, Germany
| | - Susanne Rinné
- Institute of Physiology and Pathophysiology, Marburg University, 35037 Marburg, Germany
| | - Niels Decher
- Institute of Physiology and Pathophysiology, Marburg University, 35037 Marburg, Germany
| | - Günter Schlichthörl
- Institute of Physiology and Pathophysiology, Marburg University, 35037 Marburg, Germany
| | - Jürgen Daut
- Institute of Physiology and Pathophysiology, Marburg University, 35037 Marburg, Germany
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Hao X, Li X, Li X. 17β-estradiol downregulated the expression of TASK-1 channels in mouse neuroblastoma N2A cells. J Membr Biol 2014; 247:273-9. [PMID: 24435466 DOI: 10.1007/s00232-014-9632-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Accepted: 01/06/2014] [Indexed: 01/23/2023]
Abstract
TASK channels, an acid-sensitive subgroup of two pore domain K⁺ (K2P) channels family, were widely expressed in a variety of neural tissues, and exhibited potent functions such as the regulation of membrane potential. The steroid hormone estrogen was able to interact with K⁺ channels, including voltage-gated K⁺ (Kv) and large conductance Ca²⁺-activated (BK) K⁺ channels, in different types of cells like cardiac myocytes and neurons. However, it is unclear about the effects of estrogen on TASK channels. In the present study, the expressions of two members of acid-sensitive TASK channels, TASK-1 and TASK-2, were detected in mouse neuroblastoma N2A cells by RT-PCR. Extracellular acidification (pH 6.4) weakly but statistically significantly inhibited the outward background current by 22.9 % at a holding potential of 0 mV, which inactive voltage-gated K⁺ currents, suggesting that there existed the functional TASK channels in the membrane of N2A cells. Although these currents were not altered by the acute application of 100 nM 17β-estradiol, incubation with 10 nM 17β-estradiol for 48 h reduced the mRNA level of TASK-1 channels by 40.4 % without any effect on TASK-2 channels. The proliferation rates of N2A cells were also increased by treatment with 10 nM 17β-estradiol for 48 h. These data implied that N2A cells expressed functional TASK channels and chronic exposure to 17β-estradiol downregulated the expression of TASK-1 channels and improved cell proliferation. The effect of 17β-estradiol on TASK-1 channels might be an alternative mechanism for the neuroprotective action of 17β-estradiol.
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Affiliation(s)
- Xuran Hao
- Department of Biomedical Engineering, South-Central University for Nationalities, 182 Minyuan Road, Wuhan, 430074, China
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53
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Liang B, Soka M, Christensen AH, Olesen MS, Larsen AP, Knop FK, Wang F, Nielsen JB, Andersen MN, Humphreys D, Mann SA, Huttner IG, Vandenberg JI, Svendsen JH, Haunsø S, Preiss T, Seebohm G, Olesen SP, Schmitt N, Fatkin D. Genetic variation in the two-pore domain potassium channel, TASK-1, may contribute to an atrial substrate for arrhythmogenesis. J Mol Cell Cardiol 2013; 67:69-76. [PMID: 24374141 DOI: 10.1016/j.yjmcc.2013.12.014] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 12/09/2013] [Accepted: 12/17/2013] [Indexed: 12/22/2022]
Abstract
The two-pore domain potassium channel, K2P3.1 (TASK-1) modulates background conductance in isolated human atrial cardiomyocytes and has been proposed as a potential drug target for atrial fibrillation (AF). TASK-1 knockout mice have a predominantly ventricular phenotype however, and effects of TASK-1 inactivation on atrial structure and function have yet to be demonstrated in vivo. The extent to which genetic variation in KCNK3, that encodes TASK-1, might be a determinant of susceptibility to AF is also unknown. To address these questions, we first evaluated the effects of transient knockdown of the zebrafish kcnk3a and kcnk3b genes and cardiac phenotypes were evaluated using videomicroscopy. Combined kcnk3a and kcnk3b knockdown in 72 hour post fertilization embryos resulted in lower heart rate (p<0.001), marked increase in atrial diameter (p<0.001), and mild increase in end-diastolic ventricular diameter (p=0.01) when compared with control-injected embryos. We next performed genetic screening of KCNK3 in two independent AF cohorts (373 subjects) and identified three novel KCNK3 variants. Two of these variants, present in one proband with familial AF, were located at adjacent nucleotides in the Kozak sequence and reduced expression of an engineered reporter. A third missense variant, V123L, in a patient with lone AF, reduced resting membrane potential and altered pH sensitivity in patch-clamp experiments, with structural modeling predicting instability in the vicinity of the TASK-1 pore. These in vitro data suggest that the double Kozak variants and V123L will have loss-of-function effects on ITASK. Cardiac action potential modeling predicted that reduced ITASK prolongs atrial action potential duration, and that this is potentiated by reciprocal changes in activity of other ion channel currents. Our findings demonstrate the functional importance of ITASK in the atrium and suggest that inactivation of TASK-1 may have diverse effects on atrial size and electrophysiological properties that can contribute to an arrhythmogenic substrate.
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Affiliation(s)
- Bo Liang
- Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark
| | - Magdalena Soka
- Molecular Cardiology Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia
| | - Alex Horby Christensen
- Molecular Cardiology Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia
| | - Morten S Olesen
- Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark
| | - Anders P Larsen
- Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark; Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, USA
| | - Filip K Knop
- Molecular Cardiology Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia
| | - Fan Wang
- Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark
| | - Jonas B Nielsen
- Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark
| | - Martin N Andersen
- Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark
| | - David Humphreys
- Molecular Genetics Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia
| | - Stefan A Mann
- Molecular Cardiology Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia
| | - Inken G Huttner
- Molecular Cardiology Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia
| | - Jamie I Vandenberg
- Molecular Cardiology Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia; Faculty of Medicine, University of New South Wales, Kensington, New South Wales, Australia
| | - Jesper H Svendsen
- Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark
| | - Stig Haunsø
- Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark
| | - Thomas Preiss
- John Curtin School of Medical Research, Australian National University, Canberra, Australian Capital Territory, Australia
| | - Guiscard Seebohm
- Institute for Genetics of Heart Diseases (IfGH), Department of Cardiovascular Medicine, University Hospital Münster, Germany
| | - Søren-Peter Olesen
- Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark
| | - Nicole Schmitt
- Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark.
| | - Diane Fatkin
- Molecular Cardiology Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia; Faculty of Medicine, University of New South Wales, Kensington, New South Wales, Australia; Cardiology Department, St Vincent's Hospital, Darlinghurst, New South Wales, Australia
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Seyler C, Li J, Schweizer PA, Katus HA, Thomas D. Inhibition of cardiac two-pore-domain K+ (K2P) channels by the antiarrhythmic drug vernakalant--comparison with flecainide. Eur J Pharmacol 2013; 724:51-7. [PMID: 24374008 DOI: 10.1016/j.ejphar.2013.12.030] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2013] [Revised: 12/16/2013] [Accepted: 12/18/2013] [Indexed: 01/25/2023]
Abstract
The mixed ion channel blocker, vernakalant (RSD1235), is effective in rapid conversion of atrial fibrillation (AF) to sinus rhythm (SR). Suppression of cardiac two-pore-domain potassium (K2P) channels causes action potential prolongation and has recently been proposed as a novel antiarrhythmic strategy. The objective of this study was to investigate acute effects of vernakalant on human K2P2.1 (TREK-1) and K2P3.1 (TASK-1) channels to provide a more complete picture of its antiarrhythmic mechanism of action. The class IC antiarrhythmic drug flecainide was studied as a comparator agent. Two-electrode voltage clamp and whole-cell patch clamp electrophysiology was used to record K2P currents from Xenopus oocytes and Chinese hamster ovary (CHO) cells. Vernakalant inhibited cardiac K2P2.1 channels expressed in Xenopus oocytes and in CHO cells. The IC50 value obtained from mammalian cells (13.3 µM) was close to the range of vernakalant levels reported in patients (2-8 µM), indicating potential clinical significance of K2P2.1 blockade. Open rectification characteristics and current-voltage relationships of K2P2.1 currents were not affected by vernakalant. Vernakalant did not significantly reduce K2P3.1 currents. Finally, the class I antiarrhythmic drug flecainide had no effect on K2P2.1 or K2P3.1 channels. In conclusion, the recently developed antiarrhythmic drug vernakalant targets human K2P2.1 K(+) background channels. This previously unrecognized inhibitory property adds to the multichannel blocking profile of vernakalant and extends the mechanistic basis for its anti-fibrillatory effect.
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Affiliation(s)
- Claudia Seyler
- Department of Cardiology, Medical University Hospital, Heidelberg, Im Neuenheimer Feld 410, D-69120 Heidelberg, Germany
| | - Jin Li
- Department of Cardiology, Medical University Hospital, Heidelberg, Im Neuenheimer Feld 410, D-69120 Heidelberg, Germany
| | - Patrick A Schweizer
- Department of Cardiology, Medical University Hospital, Heidelberg, Im Neuenheimer Feld 410, D-69120 Heidelberg, Germany
| | - Hugo A Katus
- Department of Cardiology, Medical University Hospital, Heidelberg, Im Neuenheimer Feld 410, D-69120 Heidelberg, Germany
| | - Dierk Thomas
- Department of Cardiology, Medical University Hospital, Heidelberg, Im Neuenheimer Feld 410, D-69120 Heidelberg, Germany.
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55
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Schmidt C, Wiedmann F, Tristram F, Anand P, Wenzel W, Lugenbiel P, Schweizer PA, Katus HA, Thomas D. Cardiac expression and atrial fibrillation-associated remodeling of K₂p2.1 (TREK-1) K⁺ channels in a porcine model. Life Sci 2013; 97:107-15. [PMID: 24345461 DOI: 10.1016/j.lfs.2013.12.006] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 11/19/2013] [Accepted: 12/05/2013] [Indexed: 01/01/2023]
Abstract
AIMS Effective management of atrial fibrillation (AF) often remains an unmet need. Cardiac two-pore-domain K(+) (K2P) channels are implicated in action potential regulation, and their inhibition has been proposed as a novel antiarrhythmic strategy. K2P2.1 (TREK-1) channels are expressed in the human heart. This study was designed to identify and functionally express porcine K2P2.1 channels. In addition, we sought to analyze cardiac expression and AF-associated K2P2.1 remodeling in a clinically relevant porcine AF model. MAIN METHODS Three pK2P2.1 isoforms were identified and amplified. Currents were recorded using voltage clamp electrophysiology in the Xenopus oocyte expression system. K2P2.1 remodeling was studied by quantitative real time PCR and Western blot in domestic pigs during AF induced by atrial burst pacing. KEY FINDINGS Human and porcine K2P2.1 proteins share 99% identity. Residues involved in phosphorylation or glycosylation are conserved. Porcine K2P2.1 channels carried outwardly rectifying K(+) currents similar to their human counterparts. In pigs, K2P2.1 was expressed ubiquitously in the heart with predominance in the atrial tissue. AF was associated with time-dependent reduction of K2P2.1 protein in the RA by 70% (7 days of AF) and 80% (21 days of AF) compared to control animals in sinus rhythm. K2P2.1 expression in the left atrium, AV node, and ventricles was not affected by AF. SIGNIFICANCE Similarities between porcine and human K2P2.1 channels indicate that the pig may represent a valid model for mechanistic and preclinical studies. AF-related atrial K2P2.1 remodeling has potential implications for arrhythmia maintenance and antiarrhythmic therapy.
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Affiliation(s)
- Constanze Schmidt
- Department of Cardiology, Medical University Hospital, Im Neuenheimer Feld 410, D-69120 Heidelberg, Germany
| | - Felix Wiedmann
- Department of Cardiology, Medical University Hospital, Im Neuenheimer Feld 410, D-69120 Heidelberg, Germany
| | - Frank Tristram
- Institute of Nanotechnology, Karlsruhe Institute of Technology, P.O. Box 3640, D-76021 Karlsruhe, Germany
| | - Priya Anand
- Institute of Nanotechnology, Karlsruhe Institute of Technology, P.O. Box 3640, D-76021 Karlsruhe, Germany
| | - Wolfgang Wenzel
- Institute of Nanotechnology, Karlsruhe Institute of Technology, P.O. Box 3640, D-76021 Karlsruhe, Germany
| | - Patrick Lugenbiel
- Department of Cardiology, Medical University Hospital, Im Neuenheimer Feld 410, D-69120 Heidelberg, Germany
| | - Patrick A Schweizer
- Department of Cardiology, Medical University Hospital, Im Neuenheimer Feld 410, D-69120 Heidelberg, Germany
| | - Hugo A Katus
- Department of Cardiology, Medical University Hospital, Im Neuenheimer Feld 410, D-69120 Heidelberg, Germany
| | - Dierk Thomas
- Department of Cardiology, Medical University Hospital, Im Neuenheimer Feld 410, D-69120 Heidelberg, Germany.
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56
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Class I antiarrhythmic drugs inhibit human cardiac two-pore-domain K+ (K2P) channels. Eur J Pharmacol 2013; 721:237-48. [DOI: 10.1016/j.ejphar.2013.09.029] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Revised: 09/04/2013] [Accepted: 09/11/2013] [Indexed: 11/22/2022]
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Harleton E, Besana A, Comas GM, Danilo P, Rosen TS, Argenziano M, Rosen MR, Robinson RB, Feinmark SJ. Ability to induce atrial fibrillation in the peri-operative period is associated with phosphorylation-dependent inhibition of TWIK protein-related acid-sensitive potassium channel 1 (TASK-1). J Biol Chem 2012; 288:2829-38. [PMID: 23229553 DOI: 10.1074/jbc.m112.404095] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Peri-operative atrial fibrillation (peri-op AF) is a common complication following thoracic surgery. This arrhythmia is thought to be triggered by an inflammatory response and can be reproduced in various animal models. Previous work has shown that the lipid inflammatory mediator, platelet-activating factor (PAF), synthesized by activated neutrophils, can induce atrial and ventricular arrhythmias as well as repolarization abnormalities in isolated ventricular myocytes. We have previously shown that carbamylated PAF-induced repolarization abnormalities result from the protein kinase C (PKC) ε-dependent phosphorylation of the two-pore domain potassium channel TASK-1. We now demonstrate that canine peri-op AF is associated with the phosphorylation-dependent loss of TASK-1 current. Further studies identified threonine 383 in the C terminus of human and canine TASK-1 as the phosphorylation site required for PAF-dependent inhibition of the channel. Using a novel phosphorylation site-specific antibody targeting the phosphorylated channel, we have determined that peri-op AF is associated with the loss of TASK-1 current and increased phosphorylation of TASK-1 at this site.
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Affiliation(s)
- Erin Harleton
- Department of Pharmacology, Columbia University Medical Center, New York, New York 10032, USA
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58
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59
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Andronic J, Bobak N, Bittner S, Ehling P, Kleinschnitz C, Herrmann AM, Zimmermann H, Sauer M, Wiendl H, Budde T, Meuth SG, Sukhorukov VL. Identification of two-pore domain potassium channels as potent modulators of osmotic volume regulation in human T lymphocytes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1828:699-707. [PMID: 23041580 DOI: 10.1016/j.bbamem.2012.09.028] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Revised: 09/21/2012] [Accepted: 09/27/2012] [Indexed: 11/17/2022]
Abstract
Many functions of T lymphocytes are closely related to cell volume homeostasis and regulation, which utilize a complex network of membrane channels for anions and cations. Among the various potassium channels, the voltage-gated K(V)1.3 is well known to contribute greatly to the osmoregulation and particularly to the potassium release during the regulatory volume decrease (RVD) of T cells faced with hypotonic environment. Here we address a putative role of the newly identified two-pore domain (K(2P)) channels in the RVD of human CD4(+) T lymphocytes, using a series of potent well known channel blockers. In the present study, the pharmacological profiles of RVD inhibition revealed K(2P)5.1 and K(2P)18.1 as the most important K(2P) channels involved in the RVD of both naïve and stimulated T cells. The impact of chemical inhibition of K(2P)5.1 and K(2P)18.1 on the RVD was comparable to that of K(V)1.3. K(2P)9.1 also notably contributed to the RVD of T cells but the extent of this contribution and its dependence on the activation status could not be unambiguously resolved. In summary, our data provide first evidence that the RVD-related potassium efflux from human T lymphocytes relies on K(2P) channels.
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Affiliation(s)
- Joseph Andronic
- University of Wuerzburg, Lehrstuhl für Biotechnologie und Biophysik, Biozentrum, Am Hubland, 97074 Wuerzburg, Germany
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Kisselbach J, Schweizer PA, Gerstberger R, Becker R, Katus HA, Thomas D. Enhancement of K2P2.1 (TREK1) background currents expressed in Xenopus oocytes by voltage-gated K+ channel β subunits. Life Sci 2012; 91:377-383. [DOI: 10.1016/j.lfs.2012.08.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2012] [Revised: 07/17/2012] [Accepted: 08/02/2012] [Indexed: 11/26/2022]
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Schiekel J, Lindner M, Hetzel A, Wemhöner K, Renigunta V, Schlichthörl G, Decher N, Oliver D, Daut J. The inhibition of the potassium channel TASK-1 in rat cardiac muscle by endothelin-1 is mediated by phospholipase C. Cardiovasc Res 2012; 97:97-105. [DOI: 10.1093/cvr/cvs285] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
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The TASK1 channel inhibitor A293 shows efficacy in a mouse model of multiple sclerosis. Exp Neurol 2012; 238:149-55. [PMID: 22960185 DOI: 10.1016/j.expneurol.2012.08.021] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Revised: 08/14/2012] [Accepted: 08/21/2012] [Indexed: 01/26/2023]
Abstract
The two-pore domain potassium channel TASK1 (KCNK3) has recently emerged as an important modulator in autoimmune CNS inflammation. Previously, it was shown that T lymphocytes obtained from TASK1(-/-) mice display impaired T cell effector functions and that TASK1(-/-) mice show a significantly reduced disease severity in myelin oligodendrocyte glycoprotein (MOG(35-55)) peptide induced experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis. We here evaluate a potent and specific TASK1 channel inhibitor, A293, which caused a dose-dependent reduction of T cell effector functions (cytokine production and proliferation). This effect was abolished in CD4(+) T cells from TASK1(-/-) mice but not in cells from TASK3(-/-) mice. In electrophysiological measurements, A293 application induced a significant reduction of the outward current of wildtype T lymphocytes, while there was no effect in TASK1(-/-) cells. Preventive and therapeutic application of A293 significantly ameliorated the EAE disease course in wildtype mice while it had no significant effect in TASK1(-/-) mice and was still partly effective in TASK3(-/-) mice. In summary, our findings support the concept of TASK1 as an attractive drug target for autoimmune disorders.
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Novel electrophysiological properties of dronedarone: inhibition of human cardiac two-pore-domain potassium (K2P) channels. Naunyn Schmiedebergs Arch Pharmacol 2012; 385:1003-16. [DOI: 10.1007/s00210-012-0780-9] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Accepted: 06/29/2012] [Indexed: 12/27/2022]
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64
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Limberg SH, Netter MF, Rolfes C, Rinné S, Schlichthörl G, Zuzarte M, Vassiliou T, Moosdorf R, Wulf H, Daut J, Sachse FB, Decher N. TASK-1 channels may modulate action potential duration of human atrial cardiomyocytes. Cell Physiol Biochem 2011; 28:613-24. [PMID: 22178873 DOI: 10.1159/000335757] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/28/2011] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND/AIMS Atrial fibrillation is the most common arrhythmia in the elderly, and potassium channels with atrium-specific expression have been discussed as targets to treat atrial fibrillation. Our aim was to characterize TASK-1 channels in human heart and to functionally describe the role of the atrial whole cell current I(TASK-1). METHODS AND RESULTS Using quantitative PCR, we show that TASK-1 is predominantly expressed in the atria, auricles and atrio-ventricular node of the human heart. Single channel recordings show the functional expression of TASK-1 in right human auricles. In addition, we describe for the first time the whole cell current carried by TASK-1 channels (I(TASK-1)) in human atrial tissue. We show that I(TASK-1) contributes to the sustained outward current I(Ksus) and that I(TASK-1) is a major component of the background conductance in human atrial cardiomyocytes. Using patch clamp recordings and mathematical modeling of action potentials, we demonstrate that modulation of I(TASK-1) can alter human atrial action potential duration. CONCLUSION Due to the lack of ventricular expression and the ability to alter human atrial action potential duration, TASK-1 might be a drug target for the treatment of atrial fibrillation.
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Affiliation(s)
- Sven H Limberg
- Institut für Physiologie und Pathophysiologie, Abteilung vegetative Physiologie, Universität Marburg, Deutschhausstraße 1-2, Marburg, Germany
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