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Song R, Chen H, Zhan R, Han M, Zhao L, Shen X. Vitamin E protects dopaminergic neurons against manganese-induced neurotoxicity through stimulation of CHRM1 and KCNJ4. J Trace Elem Med Biol 2024; 81:127326. [PMID: 37939525 DOI: 10.1016/j.jtemb.2023.127326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2023] [Revised: 10/17/2023] [Accepted: 10/19/2023] [Indexed: 11/10/2023]
Abstract
BACKGROUND Manganese (Mn) overexposure can induce neurotoxicity and lead to manganism. Vitamin E (Vit E) has neuroprotective effects by acting as an ROS scavenger, preventing mitochondrial dysfunction and neuronal apoptosis. However, the effects of Vit E on Mn-induced nigrostriatal system lesions remains unknown. OBJECTIVES We aim to investigate whether Vit E has protective effects on Mn-induced nigrostriatal system lesions and mRNA expression profiles in the SN of mice. METHODS Sixty 8-week-old C57BL/6 male mice were randomly divided into the Control, MnCl2, MnCl2 +Vit E, and Vit E group. Twenty-four hours after the last injection, the behaviour test was performed. The numbers of dopaminergic neurons in Substantia nigra (SN), the contents of dopamine and its metabolite levels in striatium, and the morphology of mitochondria and nuclei in the dopaminergic neurons in SN were detected by immunofluorescence staining, high-performance liquid chromatography, and transmission electron microscopy. Transcriptome analysis was used to analyze the signaling pathways and RT-PCR was used to verify the mRNA levels. RESULTS Vit E ameliorates behavioral disorders and attenuates the loss of nigral dopaminergic neurons in the Mn-induced mouse model. In addition, Vit E antagonized Mn-induced toxicity by restoring mitochondrial function. The results of transcriptome sequencing and RTPCR show that the protective effect of Vit E was related to the upregulation of CHRM1 and KCNJ4 mRNA in the SN. CONCLUSIONS Vit E has neuroprotective effects on Mn-induced neurodegeneration in the nigrostriatal system. This effect may be related to the upregulation of CHRM1 and KCNJ4 mRNA stimulated by Vit E in the SN.
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Affiliation(s)
- Ruihan Song
- Department of Epidemiology and Health Statistics, Medical School of Qingdao University, Qingdao, Shandong, China
| | - Huanhuan Chen
- Qingdao Municipal Center for Disease Control and Prevention/Qingdao Institute of Preventive Medicine, Qingdao, Shandong, China
| | - Runqing Zhan
- Qingdao University Affiliated Hiser Hospital, Qingdao, Shandong, China
| | - Miaomiao Han
- Department of Epidemiology and Health Statistics, Medical School of Qingdao University, Qingdao, Shandong, China
| | - Longzhu Zhao
- Department of Epidemiology and Health Statistics, Medical School of Qingdao University, Qingdao, Shandong, China
| | - Xiaoli Shen
- Department of Epidemiology and Health Statistics, Medical School of Qingdao University, Qingdao, Shandong, China.
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Classic and Novel Biomarkers as Potential Predictors of Ventricular Arrhythmias and Sudden Cardiac Death. J Clin Med 2020; 9:jcm9020578. [PMID: 32093244 PMCID: PMC7074455 DOI: 10.3390/jcm9020578] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 02/12/2020] [Accepted: 02/14/2020] [Indexed: 02/07/2023] Open
Abstract
Sudden cardiac death (SCD), most often induced by ventricular arrhythmias, is one of the main reasons for cardiovascular-related mortality. While coronary artery disease remains the leading cause of SCD, other pathologies like cardiomyopathies and, especially in the younger population, genetic disorders, are linked to arrhythmia-related mortality. Despite many efforts to enhance the efficiency of risk-stratification strategies, effective tools for risk assessment are still missing. Biomarkers have a major impact on clinical practice in various cardiac pathologies. While classic biomarkers like brain natriuretic peptide (BNP) and troponins are integrated into daily clinical practice, inflammatory biomarkers may also be helpful for risk assessment. Indeed, several trials investigated their application for the prediction of arrhythmic events indicating promising results. Furthermore, in recent years, active research efforts have brought forward an increasingly large number of “novel and alternative” candidate markers of various pathophysiological origins. Investigations of these promising biological compounds have revealed encouraging results when evaluating the prediction of arrhythmic events. To elucidate this issue, we review current literature dealing with this topic. We highlight the potential of “classic” but also “novel” biomarkers as promising tools for arrhythmia prediction, which in the future might be integrated into clinical practice.
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Liu QH, Qiao X, Zhang LJ, Wang J, Zhang L, Zhai XW, Ren XZ, Li Y, Cao XN, Feng QL, Cao JM, Wu BW. I K1 Channel Agonist Zacopride Alleviates Cardiac Hypertrophy and Failure via Alterations in Calcium Dyshomeostasis and Electrical Remodeling in Rats. Front Pharmacol 2019; 10:929. [PMID: 31507422 PMCID: PMC6718093 DOI: 10.3389/fphar.2019.00929] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 07/22/2019] [Indexed: 01/08/2023] Open
Abstract
Intracellular Ca2+ overload, prolongation of the action potential duration (APD), and downregulation of inward rectifier potassium (IK1) channel are hallmarks of electrical remodeling in cardiac hypertrophy and heart failure (HF). We hypothesized that enhancement of IK1 currents is a compensation for IK1 deficit and a novel modulation for cardiac Ca2+ homeostasis and pathological remodeling. In adult Sprague-Dawley (SD) rats in vivo, cardiac hypertrophy was induced by isoproterenol (Iso) injection (i.p., 3 mg/kg/d) for 3, 10, and 30 days. Neonatal rat ventricular myocytes (NRVMs) were isolated from 1 to 3 days SD rat pups and treated with 1 μmol/L Iso for 24 h in vitro. The effects of zacopride, a selective IK1/Kir2.1 channel agonist, on cardiac remodeling/hypertrophy were observed in the settings of 15 μg/kg in vivo and 1 μmol/L in vitro. After exposing to Iso for 3 days and 10 days, rat hearts showed distinct concentric hypertrophy and fibrosis and enhanced pumping function (P < 0.01 or P < 0.05), then progressed to dilatation and dysfunction post 30 days. Compared with the age-matched control, cardiomyocytes exhibited higher cytosolic Ca2+ (P < 0.01 or P < 0.05) and lower SR Ca2+ content (P < 0.01 or P < 0.05) all through 3, 10, and 30 days of Iso infusion. The expressions of Kir2.1 and SERCA2 were downregulated, while p-CaMKII, p-RyR2, and cleaved caspase-3 were upregulated. Iso-induced electrophysiological abnormalities were also manifested with resting potential (RP) depolarization (P < 0.01), APD prolongation (P < 0.01) in adult cardiomyocytes, and calcium overload in cultured NRVMs (P < 0.01). Zacopride treatment effectively retarded myocardial hypertrophy and fibrosis, preserved the expression of Kir2.1 and some key players in Ca2+ homeostasis, normalized the RP (P < 0.05), and abbreviated APD (P < 0.01), thus lowered cytosolic [Ca2 +]i (P < 0.01 or P < 0.05). IK1channel blocker BaCl2 or chloroquine largely reversed the cardioprotection of zacopride. We conclude that cardiac electrical remodeling is concurrent with structural remodeling. By enhancing cardiac IK1, zacopride prevents Iso-induced electrical remodeling around intracellular Ca2+ overload, thereby attenuates cardiac structural disorder and dysfunction. Early electrical interventions may provide protection on cardiac remodeling.
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Affiliation(s)
- Qing-Hua Liu
- Department of Pathophysiology, Shanxi Medical University, Taiyuan, China
| | - Xi Qiao
- Department of Pathophysiology, Shanxi Medical University, Taiyuan, China
| | - Li-Jun Zhang
- Department of Pathophysiology, Shanxi Medical University, Taiyuan, China
| | - Jin Wang
- Key Laboratory of Cellular Physiology at Shanxi Medical University, Ministry of Education, and the Department of Physiology, Shanxi Medical University, Taiyuan, China
| | - Li Zhang
- Clinical Laboratory, Children's Hospital of Shanxi, Taiyuan, China
| | - Xu-Wen Zhai
- Clinical Skills Teaching Simulation Hospital, Shanxi Medical University, Taiyuan, China
| | - Xiao-Ze Ren
- Key Laboratory of Cellular Physiology at Shanxi Medical University, Ministry of Education, and the Department of Physiology, Shanxi Medical University, Taiyuan, China
| | - Yu Li
- Department of Internal Medicine, The Hospital of Beijing Sports University, Beijing, China
| | - Xiao-Na Cao
- Department of Internal Medicine, The Hospital of Beijing Sports University, Beijing, China
| | - Qi-Long Feng
- Key Laboratory of Cellular Physiology at Shanxi Medical University, Ministry of Education, and the Department of Physiology, Shanxi Medical University, Taiyuan, China
| | - Ji-Min Cao
- Key Laboratory of Cellular Physiology at Shanxi Medical University, Ministry of Education, and the Department of Physiology, Shanxi Medical University, Taiyuan, China
| | - Bo-Wei Wu
- Key Laboratory of Cellular Physiology at Shanxi Medical University, Ministry of Education, and the Department of Physiology, Shanxi Medical University, Taiyuan, China
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Kienitz MC, Niemeyer A, König GM, Kostenis E, Pott L, Rinne A. Biased signaling of Ca 2+-sensing receptors in cardiac myocytes regulates GIRK channel activity. J Mol Cell Cardiol 2019; 130:107-121. [PMID: 30935998 DOI: 10.1016/j.yjmcc.2019.03.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 03/06/2019] [Accepted: 03/27/2019] [Indexed: 12/22/2022]
Abstract
Ca2+-sensing receptors (CaSRs) belong to the class C of G protein-coupled receptors and are activated by extracellular Ca2+. CaSRs display biased G protein signaling by coupling to different classes of heterotrimeric G proteins depending on agonist and cell type. In this study we used fluorescent biosensors to directly analyze G protein coupling to CaSRs and downstream signaling in living cells. In HEK 293 cells, CaSRs displayed biased signaling: elevation of extracellular Ca2+ or application of the alternative agonist spermine caused activation of Gi- and Gq-proteins. Adult cardiac myocytes express endogenous CaSRs, which have been implicated in regulating Ca2+ signaling and contractility. Biased signaling of CaSRs has not been investigated in these cells. To evaluate efficiencies of Gi- and Gq-signaling via CaSRs in rat atrial myocytes, we measured G protein-activated K+ (GIRK) channels. Activation of GIRK requires binding of Gβγ subunits released from Gi proteins, whereas Gq-signaling results in inhibition of GIRK channel activity. Stimulation of CaSRs by Ca2+ or spermine failed to directly activate Gi and GIRK channels. When GIRK channels were pre-activated via endogenous M2 receptors, stimulation of CaSRs caused pronounced inhibition of GIRK currents. This effect was specific to CaSR activation: GIRK current inhibition was sensitive to NPS-2143, a negative allosteric modulator of CaSRs, and abrogated by FR900359, a direct inhibitor of Gq. GIRK current inhibition was also sensitive to the PKC inhibitor chelerythrine, suggesting that following activation of CaSR and Gq, GIRK currents are modulated by PKC phosphorylation. We conclude from this data that cardiac CaSRs do not activate Gi and affect GIRK currents preferentially via the Gq/PKC pathway.
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Affiliation(s)
| | - Anne Niemeyer
- Department of Physiology, Ruhr University Bochum, Bochum, Germany
| | - Gabriele M König
- Institute of Pharmaceutical Biology, University of Bonn, Bonn, Germany
| | - Evi Kostenis
- Institute of Pharmaceutical Biology, University of Bonn, Bonn, Germany
| | - Lutz Pott
- Department of Physiology, Ruhr University Bochum, Bochum, Germany
| | - Andreas Rinne
- Department of Physiology, Ruhr University Bochum, Bochum, Germany
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Goversen B, van der Heyden MAG, van Veen TAB, de Boer TP. The immature electrophysiological phenotype of iPSC-CMs still hampers in vitro drug screening: Special focus on I K1. Pharmacol Ther 2017; 183:127-136. [PMID: 28986101 DOI: 10.1016/j.pharmthera.2017.10.001] [Citation(s) in RCA: 91] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Preclinical drug screens are not based on human physiology, possibly complicating predictions on cardiotoxicity. Drug screening can be humanised with in vitro assays using human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs). However, in contrast to adult ventricular cardiomyocytes, iPSC-CMs beat spontaneously due to presence of the pacemaking current If and reduced densities of the hyperpolarising current IK1. In adult cardiomyocytes, IK1 finalises repolarisation by stabilising the resting membrane potential while also maintaining excitability. The reduced IK1 density contributes to proarrhythmic traits in iPSC-CMs, which leads to an electrophysiological phenotype that might bias drug responses. The proarrhythmic traits can be suppressed by increasing IK1 in a balanced manner. We systematically evaluated all studies that report strategies to mature iPSC-CMs and found that only few studies report IK1 current densities. Furthermore, these studies did not succeed in establishing sufficient IK1 levels as they either added too little or too much IK1. We conclude that reduced densities of IK1 remain a major flaw in iPSC-CMs, which hampers their use for in vitro drug screening.
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Affiliation(s)
- Birgit Goversen
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Yalelaan 50, 3584 CM, Utrecht, The Netherlands
| | - Marcel A G van der Heyden
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Yalelaan 50, 3584 CM, Utrecht, The Netherlands
| | - Toon A B van Veen
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Yalelaan 50, 3584 CM, Utrecht, The Netherlands
| | - Teun P de Boer
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Yalelaan 50, 3584 CM, Utrecht, The Netherlands.
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The Genetics of Asymmetry: Whole Exome Sequencing in a Consanguineous Turkish Family with an Overrepresentation of Left-Handedness. Symmetry (Basel) 2017. [DOI: 10.3390/sym9050066] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
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Scherer D, Schworm B, Seyler C, Xynogalos P, Scholz EP, Thomas D, Katus HA, Zitron E. Inhibition of inwardly rectifying Kir2.x channels by the novel anti-cancer agent gambogic acid depends on both pore block and PIP 2 interference. Naunyn Schmiedebergs Arch Pharmacol 2017; 390:701-710. [PMID: 28365825 DOI: 10.1007/s00210-017-1372-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 03/23/2017] [Indexed: 12/21/2022]
Abstract
The caged xanthone gambogic acid (GA) is a novel anti-cancer agent which exhibits anti-proliferative, anti-inflammatory and cytotoxic effects in many types of cancer tissues. In a recent phase IIa study, GA exhibits a favourable safety profile. However, limited data are available concerning its interaction with cardiac ion channels. Heteromeric assembly of Kir2.x channels underlies the cardiac inwardly rectifying IK1 current which is responsible for the stabilization of the diastolic resting membrane potential. Inhibition of the cardiac IK1 current may lead to ventricular arrhythmia due to delayed afterdepolarizations. Compared to Kv2.1, hERG and Kir1.1, a slow, delayed inhibition of Kir2.1 channels by GA in a mammalian cell line was reported before but no data exist in literature concerning action of GA on homomeric Kir2.2 and Kir2.3 and heteromeric Kir2.x channels. Therefore, the aim of this study was to provide comparative data on the effect of GA on homomeric and heteromeric Kir2.x channels. Homomeric and heteromeric Kir2.x channels were heterologously expressed in Xenopus oocytes, and the two-microelectrode voltage-clamp technique was used to record Kir2.x currents. To investigate the mechanism of the channel inhibition by GA, alanine-mutated Kir2.x channels with modifications in the channels pore region or at phosphatidylinositol 4,5-bisphosphate (PIP2)-binding sites were employed. GA caused a slow inhibition of homomeric and heteromeric Kir2.x channels at low micromolar concentrations (with IC50 Kir2.1/2.2 < Kir2.2 < Kir2.2/2.3 < Kir2.3 < Kir2.1 < Kir2.1/2.3). The effect did not reach saturation within 60 min and was not reversible upon washout for 30 min. The inhibition showed no strong voltage dependence. We provide evidence for a combination of direct channel pore blockade and a PIP2-dependent mechanism as a molecular basis for the observed effect. We conclude that Kir2.x channel inhibition by GA may be relevant in patients with pre-existing cardiac disorders such as chronic heart failure or certain rhythm disorders and recommend a close cardiac monitoring for those patients when treated with GA.
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Affiliation(s)
- Daniel Scherer
- Department of Cardiology, Medical University Hospital Heidelberg, Im Neuenheimer Feld 410, D-69120, Heidelberg, Germany.
| | - Benedikt Schworm
- Department of Cardiology, Medical University Hospital Heidelberg, Im Neuenheimer Feld 410, D-69120, Heidelberg, Germany
| | - Claudia Seyler
- Department of Cardiology, Medical University Hospital Heidelberg, Im Neuenheimer Feld 410, D-69120, Heidelberg, Germany.,DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, Heidelberg, Germany
| | - Panagiotis Xynogalos
- Department of Cardiology, Medical University Hospital Heidelberg, Im Neuenheimer Feld 410, D-69120, Heidelberg, Germany
| | - Eberhard P Scholz
- 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.,DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, Heidelberg, Germany
| | - Hugo A Katus
- Department of Cardiology, Medical University Hospital Heidelberg, Im Neuenheimer Feld 410, D-69120, Heidelberg, Germany.,DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, Heidelberg, Germany
| | - Edgar Zitron
- Department of Cardiology, Medical University Hospital Heidelberg, Im Neuenheimer Feld 410, D-69120, Heidelberg, Germany.,DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, Heidelberg, Germany
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8
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Scherer D, Seyler C, Xynogalos P, Scholz EP, Thomas D, Backs J, Andrassy M, Völkers M, Karle CA, Katus HA, Zitron E. Inhibition of Cardiac Kir Current (IK1) by Protein Kinase C Critically Depends on PKCβ and Kir2.2. PLoS One 2016; 11:e0156181. [PMID: 27214373 PMCID: PMC4877014 DOI: 10.1371/journal.pone.0156181] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Accepted: 05/10/2016] [Indexed: 11/19/2022] Open
Abstract
Background Cardiac inwardly rectifying Kir current (IK1) mediates terminal repolarisation and is critical for the stabilization of the diastolic membrane potential. Its predominant molecular basis in mammalian ventricle is heterotetrameric assembly of Kir2.1 and Kir2.2 channel subunits. It has been shown that PKC inhibition of IK1 promotes focal ventricular ectopy. However, the underlying molecular mechanism has not been fully elucidated to date. Methods and Results In the Xenopus oocyte expression system, we observed a pronounced PKC-induced inhibition of Kir2.2 but not Kir2.1 currents. The PKC regulation of Kir2.2 could be reproduced by an activator of conventional PKC isoforms and antagonized by pharmacological inhibition of PKCβ. In isolated ventricular cardiomyocytes (rat, mouse), pharmacological activation of conventional PKC isoforms induced a pronounced inhibition of IK1. The PKC effect in rat ventricular cardiomyocytes was markedly attenuated following co-application of a small molecule inhibitor of PKCβ. Underlining the critical role of PKCβ, the PKC-induced inhibition of IK1 was absent in homozygous PKCβ knockout-mice. After heterologous expression of Kir2.1-Kir2.2 concatemers in Xenopus oocytes, heteromeric Kir2.1/Kir2.2 currents were also inhibited following activation of PKC. Conclusion We conclude that inhibition of cardiac IK1 by PKC critically depends on the PKCβ isoform and Kir2.2 subunits. This regulation represents a potential novel target for the antiarrhythmic therapy of focal ventricular arrhythmias.
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Affiliation(s)
- Daniel Scherer
- Department of Cardiology, Medical University Hospital Heidelberg, Heidelberg, Germany
- * E-mail:
| | - Claudia Seyler
- Department of Cardiology, Medical University Hospital Heidelberg, Heidelberg, Germany
| | - Panagiotis Xynogalos
- Department of Cardiology, Medical University Hospital Heidelberg, Heidelberg, Germany
| | - Eberhard P. Scholz
- Department of Cardiology, Medical University Hospital Heidelberg, Heidelberg, Germany
| | - Dierk Thomas
- Department of Cardiology, Medical University Hospital Heidelberg, Heidelberg, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, Heidelberg, Germany
| | - Johannes Backs
- Department of Cardiology, Medical University Hospital Heidelberg, Heidelberg, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, Heidelberg, Germany
| | - Martin Andrassy
- Department of Cardiology, Medical University Hospital Heidelberg, Heidelberg, Germany
| | - Mirko Völkers
- Department of Cardiology, Medical University Hospital Heidelberg, Heidelberg, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, Heidelberg, Germany
| | - Christoph A. Karle
- Department of Cardiology, Medical University Hospital Heidelberg, Heidelberg, Germany
| | - Hugo A. Katus
- Department of Cardiology, Medical University Hospital Heidelberg, Heidelberg, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, Heidelberg, Germany
| | - Edgar Zitron
- Department of Cardiology, Medical University Hospital Heidelberg, Heidelberg, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, Heidelberg, Germany
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On the risk concerns of zacopride, a moderate IK1 channel agonist with cardiac protective action. J Cardiovasc Pharmacol 2014; 64:357-9. [PMID: 25072868 DOI: 10.1097/fjc.0000000000000148] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Zacopride, an IK1 agonist with moderate potency, could exert significant antiarrhythmic and cardiac protective effects. To date, there is no report to show that zacopride is proarrhythmic in both experimental studies and clinical trials. However, in certain cardiac pathological conditions, especially short QT syndrome and certain reentry tachycardia, zacopride is not suggested. Further studies are needed to precisely evaluate the potential arrhythmogenic risk of zacopride.
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10
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Schmitt N, Grunnet M, Olesen SP. Cardiac potassium channel subtypes: new roles in repolarization and arrhythmia. Physiol Rev 2014; 94:609-53. [PMID: 24692356 DOI: 10.1152/physrev.00022.2013] [Citation(s) in RCA: 160] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
About 10 distinct potassium channels in the heart are involved in shaping the action potential. Some of the K+ channels are primarily responsible for early repolarization, whereas others drive late repolarization and still others are open throughout the cardiac cycle. Three main K+ channels drive the late repolarization of the ventricle with some redundancy, and in atria this repolarization reserve is supplemented by the fairly atrial-specific KV1.5, Kir3, KCa, and K2P channels. The role of the latter two subtypes in atria is currently being clarified, and several findings indicate that they could constitute targets for new pharmacological treatment of atrial fibrillation. The interplay between the different K+ channel subtypes in both atria and ventricle is dynamic, and a significant up- and downregulation occurs in disease states such as atrial fibrillation or heart failure. The underlying posttranscriptional and posttranslational remodeling of the individual K+ channels changes their activity and significance relative to each other, and they must be viewed together to understand their role in keeping a stable heart rhythm, also under menacing conditions like attacks of reentry arrhythmia.
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11
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Kolettis TM, Oikonomidis DL, Baibaki MEE, Barka E, Kontonika M, Tsalikakis DG, Papalois A, Kyriakides ZS. Endothelin B-receptors and sympathetic activation: impact on ventricular arrhythmogenesis during acute myocardial infarction. Life Sci 2014; 118:281-7. [PMID: 24503339 DOI: 10.1016/j.lfs.2014.01.069] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Revised: 12/26/2013] [Accepted: 01/23/2014] [Indexed: 12/26/2022]
Abstract
AIMS We investigated the role of endothelin-B receptors on sympathetic activation originating from the adrenal gland or from the myocardium and its impact on arrhythmogenesis during acute myocardial infarction. MAIN METHODS We studied two groups of rats (n=120, 284±2 g), namely wild-type and ETB-deficient. Myocardial infarction was induced by permanent ligation of the left coronary artery and ventricular tachyarrhythmias were evaluated from continuous electrocardiographic recordings. Sympathetic activation, measured by indices of heart rate variability, was evaluated after adrenalectomy or catecholamine depletion induced by reserpine. Acute left ventricular failure was assessed by total animal activity. KEY FINDINGS Adrenalectomy decreased the total duration of tachyarrhythmias in ETB-deficient rats, but their incidence remained higher, compared to wild-type rats. After reserpine, heart rate variability indices and tachyarrhythmias were similar in the two groups during the initial, ischaemic phase. During evolving infarction, tachyarrhythmia duration was longer in ETB-deficient rats, despite lower sympathetic activation. Heart rate was lower in ETB-deficient rats throughout the 24-hour observation period, whereas activity was comparable in the two groups. SIGNIFICANCE Endothelin-B receptors modulate sympathetic activation during acute myocardial infarction not only in the ventricular myocardium, but also in the adrenal gland. Sympathetic activation markedly increases early-phase ventricular tachyarrhythmias, but other mechanisms involving the endothelin system underlie delayed arrhythmogenesis.
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Affiliation(s)
- Theofilos M Kolettis
- Department of Cardiology, University of Ioannina, Ioannina, Greece; Cardiovascular Research Institute, Ioannina and Athens, Greece.
| | | | - Maria-Eleni E Baibaki
- Department of Cardiology, University of Ioannina, Ioannina, Greece; Cardiovascular Research Institute, Ioannina and Athens, Greece; Experimental Research Center ELPEN, Pikermi, Athens, Greece
| | - Eleonora Barka
- Department of Materials Science and Engineering, University of Ioannina, Greece
| | - Marianthi Kontonika
- Department of Cardiology, University of Ioannina, Ioannina, Greece; Cardiovascular Research Institute, Ioannina and Athens, Greece
| | - Dimitrios G Tsalikakis
- Engineering Informatics and Telecommunications, University of Western Macedonia, Kozani, Greece
| | - Apostolos Papalois
- Cardiovascular Research Institute, Ioannina and Athens, Greece; Experimental Research Center ELPEN, Pikermi, Athens, Greece
| | - Zenon S Kyriakides
- Cardiovascular Research Institute, Ioannina and Athens, Greece; First Department of Cardiology, Red Cross Hospital, Athens, Greece
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12
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Kolettis TM. Ventricular tachyarrhythmias during acute myocardial infarction: the role of endothelin-1. Life Sci 2014; 118:136-40. [PMID: 24486303 DOI: 10.1016/j.lfs.2014.01.060] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Revised: 12/23/2013] [Accepted: 01/13/2014] [Indexed: 11/16/2022]
Abstract
Ventricular arrhythmogenesis during acute coronary syndromes is a common cause of sudden cardiac death, but the underlying mechanisms remain incompletely understood. Recent evidence indicates an emerging pathophysiologic role of endothelin-1 during myocardial ischaemia and evolving infarction. At the early stages post-coronary occlusion, endothelin-1 enhances sympathetic activation, an effect mediated via the ETA receptor, whereas the ETB receptor exerts protective actions. The importance of this interaction is clearly decreased during subsequent stages, during which endothelin-1 may participate in the genesis of ventricular tachycardia or fibrillation via other mechanisms; of these, the effects of endothelin-1 on repolarizing potassium currents and electrical conduction via gap junctions merit further research. The relative roles of ETA and ETB receptors during this phase are unclear. Evaluation of the arrhythmogenic effects of endothelin-1 during acute coronary syndromes may provide the tools towards lowering sudden cardiac death rates.
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Affiliation(s)
- Theofilos M Kolettis
- Department of Cardiology, University of Ioannina, Cardiovascular Research Institute, Ioannina and Athens, Greece.
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Yu L, Li M, She T, Shi C, Meng W, Wang B, Cheng M. Endothelin-1 stimulates the expression of L-type Ca2+ channels in neonatal rat cardiomyocytes via the extracellular signal-regulated kinase 1/2 pathway. J Membr Biol 2013; 246:343-53. [PMID: 23546014 DOI: 10.1007/s00232-013-9538-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2012] [Accepted: 03/16/2013] [Indexed: 01/07/2023]
Abstract
The cardiac L-type Ca(2+) channel current (I(Ca,L)) plays an important role in controlling both cardiac excitability and excitation-contraction coupling and is involved in the electrical remodeling during postnatal heart development and cardiac hypertrophy. However, the possible role of endothelin-1 (ET-1) in the electrical remodeling of postnatal and diseased hearts remains unclear. Therefore, the present study was designed to investigate the transcriptional regulation of I(Ca,L) mediated by ET-1 in neonatal rat ventricular myocytes using the whole-cell patch-clamp technique, quantitative RT-PCR and Western blotting. Furthermore, we determined whether the extracellular signal-regulated kinase 1/2 (ERK1/2) pathway is involved. ET-1 increased I(Ca,L) density without altering its voltage dependence of activation and inactivation. In line with the absence of functional changes, ET-1 increased L-type Ca(2+) channel pore-forming α1C-subunit mRNA and protein levels without affecting the mRNA expression of auxiliary β- and α2/δ-subunits. Furthermore, an actinomycin D chase experiment revealed that ET-1 did not alter α1C-subunit mRNA stability. These effects of ET-1 were inhibited by the ETA receptor antagonist BQ-123 but not the ETB receptor antagonist BQ-788. Moreover, the effects of ET-1 on I(Ca,L) and α1C-subunit expression were abolished by the ERK1/2 inhibitor (PD98059) but not by the p38 MAPK inhibitor (SB203580) or the c-Jun N-terminal kinase inhibitor (SP600125). These findings indicate that ET-1 increased the transcription of L-type Ca(2+) channel in cardiomyocytes via activation of ERK1/2 through the ETA receptor, which may contribute to the electrical remodeling of heart during postnatal development and cardiac hypertrophy.
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Affiliation(s)
- Liangzhu Yu
- Hubei Province Key Laboratory on Cardiovascular, Cerebrovascular, and Metabolic Disorders, Hubei University of Science and Technology, Xianning, Peoples Republic of China.
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Seyler C, Duthil-Straub E, Zitron E, Gierten J, Scholz EP, Fink RHA, Karle CA, Becker R, Katus HA, Thomas D. TASK1 (K(2P)3.1) K(+) channel inhibition by endothelin-1 is mediated through Rho kinase-dependent phosphorylation. Br J Pharmacol 2012; 165:1467-75. [PMID: 21838752 DOI: 10.1111/j.1476-5381.2011.01626.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND AND PURPOSE TASK1 (K(2P)3.1) two-pore-domain K(+) channels contribute substantially to the resting membrane potential in human pulmonary artery smooth muscle cells (hPASMC), modulating vascular tone and diameter. The endothelin-1 (ET-1) pathway mediates vasoconstriction and is an established target of pulmonary arterial hypertension (PAH) therapy. ET-1-mediated inhibition of TASK1 currents in hPASMC is implicated in the pathophysiology of PAH. This study was designed to elucidate molecular mechanisms underlying inhibition of TASK1 channels by ET-1. EXPERIMENTAL APPROACH Two-electrode voltage clamp and whole-cell patch clamp electrophysiology was used to record TASK1 currents from hPASMC and Xenopus oocytes. KEY RESULTS ET-1 inhibited TASK1-mediated I(KN) currents in hPASMC, an effect attenuated by Rho kinase inhibition with Y-27632. In Xenopus oocytes, TASK1 current reduction by ET-1 was mediated by endothelin receptors ET(A) (IC(50) = 0.08 nM) and ET(B) (IC(50) = 0.23 nM) via Rho kinase signalling. TASK1 channels contain two putative Rho kinase phosphorylation sites, Ser(336) and Ser(393) . Mutation of Ser(393) rendered TASK1 channels insensitive to ET(A) - or ET(B)-mediated current inhibition. In contrast, removal of Ser(336) selectively attenuated ET(A) -dependent TASK1 regulation without affecting the ET(B) pathway. CONCLUSIONS AND IMPLICATIONS ET-1 regulated vascular TASK1 currents through ET(A) and ET(B) receptors mediated by downstream activation of Rho kinase and direct channel phosphorylation. The Rho kinase pathway in PASMC may provide a more specific therapeutic target in pulmonary arterial hypertension treatment.
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Affiliation(s)
- C Seyler
- Department of Cardiology, Medical University Hospital Heidelberg, Heidelberg, Germany
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Rahm AK, Gierten J, Kisselbach J, Staudacher I, Staudacher K, Schweizer PA, Becker R, Katus HA, Thomas D. PKC-dependent activation of human K(2P) 18.1 K(+) channels. Br J Pharmacol 2012; 166:764-73. [PMID: 22168364 DOI: 10.1111/j.1476-5381.2011.01813.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND AND PURPOSE Two-pore-domain K(+) channels (K(2P) ) mediate K(+) background currents that modulate the membrane potential of excitable cells. K(2P) 18.1 (TWIK-related spinal cord K(+) channel) provides hyperpolarizing background currents in neurons. Recently, a dominant-negative loss-of-function mutation in K(2P) 18.1 has been implicated in migraine, and activation of K(2P) 18.1 channels was proposed as a therapeutic strategy. Here we elucidated the molecular mechanisms underlying PKC-dependent activation of K(2P) 18.1 currents. EXPERIMENTAL APPROACH Human K(2P) 18.1 channels were heterologously expressed in Xenopus laevis oocytes, and currents were recorded with the two-electrode voltage clamp technique. KEY RESULTS Stimulation of PKC using phorbol 12-myristate-13-acetate (PMA) activated the hK(2P) 18.1 current by 3.1-fold in a concentration-dependent fashion. The inactive analogue 4α-PMA had no effect on channel activity. The specific PKC inhibitors bisindolylmaleimide I, Ro-32-0432 and chelerythrine reduced PMA-induced channel activation indicating that PKC is involved in this effect of PMA. Selective activation of conventional PKC isoforms with thymeleatoxin (100 nM) did not reproduce K(2P) 18.1 channel activation. Current activation by PMA was not affected by pretreatment with CsA (calcineurin inhibitor) or KT 5720 (PKA inhibitor), ruling out a significant contribution of calcineurin or cross-talk with PKA to the PKC-dependent hK(2P) 18.1 activation. Finally, mutation of putative PKC phosphorylation sites did not prevent PMA-induced K(2P) 18.1 channel activation. CONCLUSIONS AND IMPLICATIONS We demonstrated that activation of hK(2P) 18.1 (TRESK) by PMA is mediated by PKC stimulation. Hence, PKC-mediated activation of K(2P) 18.1 background currents may serve as a novel molecular target for migraine treatment.
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Affiliation(s)
- Ann-Kathrin Rahm
- Department of Cardiology, Medical University Hospital Heidelberg, Heidelberg, Germany
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Central role of PKCα in isoenzyme-selective regulation of cardiac transient outward current Ito and Kv4.3 channels. J Mol Cell Cardiol 2011; 51:722-9. [PMID: 21803046 DOI: 10.1016/j.yjmcc.2011.07.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2011] [Revised: 07/08/2011] [Accepted: 07/11/2011] [Indexed: 11/20/2022]
Abstract
The transient outward current I(to) is an important determinant of the early repolarization phase. I(to) and its molecular basis Kv4.3 are regulated by adrenergic pathways including protein kinase C. However, the exact regulatory mechanisms have not been analyzed yet. We here analyzed isoenzyme specific regulation of Kv4.3 and I(to) by PKC. Kv4.3 channels were expressed in Xenopus oocytes and currents were measured with double electrode voltage clamp technique. Patch clamp experiments were performed in isolated rat cardiomyocytes. Unspecific PKC stimulation with PMA resulted in a reduction of Kv4.3 current. Similar effects could be observed after activation of conventional PKC isoforms by TMX. Both effects were reversible by pharmacological inhibition of the conventional PKC isoenzymes (Gö6976). In contrast, activation of the novel PKC isoforms (ingenol) did not significantly affect Kv4.3 current. Whereas TMX-induced PKC activation was not attenuated inhibition of PKCβ, inhibition of PKCα with HBDDE prevented inhibitory effects of both PMA and TMX. Accordingly, stimulatory effects of PMA and TMX could be mimicked by the α-isoenzyme selective PKC activator iripallidal. Further evidence for the central role of PKCα was provided with the use of siRNAs. We found that PKCα siRNA but not PKCβ siRNA abolished the TMX induced effect. In isolated rat cardiomyocytes, PMA dependent I(to) reduction could be completely abolished by pharmacologic inhibition of PKCα. In summary we show that PKCα plays a central role in protein kinase C dependent regulation of Kv4.3 current and native I(to). These results add to the current understanding of isoenzyme selective ion channel regulation by protein kinases.
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Staudacher K, Staudacher I, Ficker E, Seyler C, Gierten J, Kisselbach J, Rahm AK, Trappe K, Schweizer PA, Becker R, Katus HA, Thomas D. Carvedilol targets human K2P 3.1 (TASK1) K+ leak channels. Br J Pharmacol 2011; 163:1099-110. [PMID: 21410455 PMCID: PMC3130955 DOI: 10.1111/j.1476-5381.2011.01319.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2010] [Revised: 01/20/2011] [Accepted: 02/05/2011] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND AND PURPOSE Human K(2P) 3.1 (TASK1) channels represent potential targets for pharmacological management of atrial fibrillation. K(2P) channels control excitability by stabilizing membrane potential and by expediting repolarization. In the heart, inhibition of K(2P) currents by class III antiarrhythmic drugs results in action potential prolongation and suppression of electrical automaticity. Carvedilol exerts antiarrhythmic activity and suppresses atrial fibrillation following cardiac surgery or cardioversion. The objective of this study was to investigate acute effects of carvedilol on human K(2P) 3.1 (hK(2P) 3.1) channels. EXPERIMENTAL APPROACH Two-electrode voltage clamp and whole-cell patch clamp electrophysiology was used to record hK(2P) 3.1 currents from Xenopus oocytes, Chinese hamster ovary (CHO) cells and human pulmonary artery smooth muscle cells (hPASMC). KEY RESULTS Carvedilol concentration-dependently inhibited hK(2P) 3.1 currents in Xenopus oocytes (IC(50) = 3.8 µM) and in mammalian CHO cells (IC(50) = 0.83 µM). In addition, carvedilol sensitivity of native I(K2P3.1) was demonstrated in hPASMC. Channels were blocked in open and closed states in frequency-dependent fashion, resulting in resting membrane potential depolarization by 7.7 mV. Carvedilol shifted the current-voltage (I-V) relationship by -6.9 mV towards hyperpolarized potentials. Open rectification, characteristic of K(2P) currents, was not affected. CONCLUSIONS AND IMPLICATIONS The antiarrhythmic drug carvedilol targets hK(2P) 3.1 background channels. We propose that cardiac hK(2P) 3.1 current blockade may suppress electrical automaticity, prolong atrial refractoriness and contribute to the class III antiarrhythmic action in patients treated with the drug.
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Affiliation(s)
- K Staudacher
- Department of Cardiology, Medical University Hospital HeidelbergHeidelberg, Germany
| | - I Staudacher
- Department of Cardiology, Medical University Hospital HeidelbergHeidelberg, Germany
| | - E Ficker
- Rammelkamp Center, MetroHealth Campus, Case Western Reserve UniversityCleveland, OH, USA
| | - C Seyler
- Department of Cardiology, Medical University Hospital HeidelbergHeidelberg, Germany
| | - J Gierten
- Department of Cardiology, Medical University Hospital HeidelbergHeidelberg, Germany
| | - J Kisselbach
- Department of Cardiology, Medical University Hospital HeidelbergHeidelberg, Germany
| | - A-K Rahm
- Department of Cardiology, Medical University Hospital HeidelbergHeidelberg, Germany
| | - K Trappe
- Department of Cardiology, Medical University Hospital HeidelbergHeidelberg, Germany
| | - PA Schweizer
- Department of Cardiology, Medical University Hospital HeidelbergHeidelberg, Germany
| | - R Becker
- Department of Cardiology, Medical University Hospital HeidelbergHeidelberg, Germany
| | - HA Katus
- Department of Cardiology, Medical University Hospital HeidelbergHeidelberg, Germany
| | - D Thomas
- Department of Cardiology, Medical University Hospital HeidelbergHeidelberg, Germany
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Mueller EE, Momen A, Massé S, Zhou YQ, Liu J, Backx PH, Henkelman RM, Nanthakumar K, Stewart DJ, Husain M. Electrical remodelling precedes heart failure in an endothelin-1-induced model of cardiomyopathy. Cardiovasc Res 2011; 89:623-33. [PMID: 21062919 DOI: 10.1093/cvr/cvq351] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2023] Open
Abstract
AIMS Binary transgenic (BT) mice with doxycycline (DOX)-suppressible cardiac-specific overexpression of endothelin-1 (ET-1) exhibit progressive heart failure (HF), QRS prolongation, and death following DOX withdrawal. However, the molecular basis and reversibility of the electrophysiological abnormalities in this model were not known. Here, we assess the mechanisms underlying ET-1-mediated electrical remodelling, and its role in HF. METHODS AND RESULTS BT vs. non-BT littermate controls were withdrawn from DOX and serially studied with ultrasound biomicroscopy, octapolar catheters, multielectrode epicardial mapping, histopathology, western blot, immunohistochemistry, and qRT-PCR. Abnormalities in ventricular activation and -dV/dt were detected as early as 4 weeks after transgene activation, when the structure and function of the heart remained unaffected. By 8 weeks of ET-1 overexpression, biventricular systolic and diastolic dysfunction, myocardial fibrosis, and cardiomyocyte hypertrophy were observed. Intracardiac and epicardial electrograms revealed prolonged conduction and ventricular activation, reduced -dV/dt, and abnormal atrioventricular nodal function. Within 4 weeks of ET-1 induction, connexin 40 (Cx40) protein and Cx43 mRNA, protein, and phosphorylation levels were reduced by 36, 64, 93, and 69%, respectively; Na(v)1.5 mRNA and protein levels were reduced by 30 and 50%, respectively, as was Na(+) channel conductance. Importantly, the associated electrophysiological abnormalities at this time point were reversible upon suppression of ET-1 overexpression and completely prevented the development of structural and functional remodelling. CONCLUSION ET-1-mediated electrical remodelling correlates with reduced Cx40, Cx43, and Na(v)1.5 expression and decreased Na(+) channel conductance and precedes HF. The sequence and reversibility of this phenotype suggest that a primary abnormality in electrical remodelling may contribute to the pathogenesis of HF.
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Affiliation(s)
- Erin E Mueller
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
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Deng W, Baki L, Baumgarten CM. Endothelin signalling regulates volume-sensitive Cl- current via NADPH oxidase and mitochondrial reactive oxygen species. Cardiovasc Res 2010; 88:93-100. [PMID: 20444986 DOI: 10.1093/cvr/cvq125] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
AIMS We assessed regulation of volume-sensitive Cl(-) current (I(Cl,swell)) by endothelin-1 (ET-1) and characterized the signalling pathway responsible for its activation in rabbit atrial and ventricular myocytes. METHODS AND RESULTS ET-1 elicited I(Cl,swell) under isosmotic conditions. Outwardly rectified Cl(-) current was blocked by the I(Cl,swell)-selective inhibitor DCPIB or osmotic shrinkage and involved ET(A) but not ET(B) receptors. ET-1-induced current was abolished by inhibiting epidermal growth factor receptor (EGFR) kinase or phosphoinositide-3-kinase (PI-3K), indicating that these kinases were downstream. Regarding upstream events, activation of I(Cl,swell) by osmotic swelling or angiotensin II (AngII) was suppressed by ET(A) blockade, whereas AngII AT(1) receptor blockade failed to alter ET-1-induced current. Reactive oxygen species (ROS) produced by NADPH oxidase (NOX) stimulate I(Cl,swell). As expected, blockade of NOX suppressed ET-1-induced I(Cl,swell), but blockade of mitochondrial ROS production with rotenone also suppressed I(Cl,swell). I(Cl,swell) was activated by augmenting complex III ROS production with antimycin A or diazoxide; in this case, I(Cl,swell) was insensitive to NOX inhibitors, indicating that mitochondria were downstream from NOX. ROS generation in HL-1 cardiomyocytes measured by flow cytometry confirmed the electrophysiological findings. ET-1-induced ROS production was inhibited by blocking either NOX or mitochondrial complex I, whereas complex III-induced ROS production was insensitive to NOX blockade. CONCLUSION ET-1-ET(A) signalling activated I(Cl,swell) via EGFR kinase, PI-3K, and NOX ROS production, which triggered mitochondrial ROS production. ET(A) receptors were downstream effectors when I(Cl,swell) was elicited by osmotic swelling or AngII. These data suggest that ET-1-induced ROS-dependent I(Cl,swell) is likely to participate in multiple physiological and pathophysiological processes.
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Affiliation(s)
- Wu Deng
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, VA 23298-0551, USA
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Mass spectrometric analysis reveals a functionally important PKA phosphorylation site in a Kir3 channel subunit. Pflugers Arch 2009; 458:303-14. [PMID: 19151997 DOI: 10.1007/s00424-008-0628-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2008] [Accepted: 12/20/2008] [Indexed: 01/18/2023]
Abstract
Phosphorylation of the Kir3 channel by cAMP-dependent protein kinase (PKA) potentiates activity and strengthens channel-PIP(2) interactions, whereas phosphorylation by protein kinase C (PKC) exerts the opposite effects (Keselman et al., Channels 1:113-123, 2007; Lopes et al., Channels 1:124-134, 2007). Unequivocal identification of phosphorylated residues in ion channel proteins has been difficult, but recent advances in mass spectrometry techniques have allowed precise identification of phosphorylation sites (Park et al., Science 313:976-979, 2006). In this study, we utilized mass spectrometry to identify phosphorylation sites within the Kir3.1 channel subunit. We focused on the Kir3.1 C-terminal cytosolic domain that has been reported to be regulated by several modulators. In vitro phosphorylation by PKA exhibited a convincing signal upon treatment with a phosphoprotein stain. The phosphorylated C terminus was subjected to mass spectrometric analysis using matrix-assisted lased desorption/ionization-time of flight mass spectroscopy (MS). Peptides whose mass underwent a shift corresponding to addition of a phosphate group were then subjected to tandem MS (MS/MS) in order to confirm the modification and determine its precise location. Using this approach, we identified S385 as an in vitro phosphorylation site. Mutation of this residue to alanine resulted in a reduced sensitivity of Kir3.1* currents to H89 and Forskolin, confirming an in vivo role for this novel site of the Kir3.1 channel subunit in its regulation by PKA.
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Zitron E, Günth M, Scherer D, Kiesecker C, Kulzer M, Bloehs R, Scholz EP, Thomas D, Weidenhammer C, Kathöfer S, Bauer A, Katus HA, Karle CA. Kir2.x inward rectifier potassium channels are differentially regulated by adrenergic α1A receptors. J Mol Cell Cardiol 2008; 44:84-94. [DOI: 10.1016/j.yjmcc.2007.10.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2007] [Revised: 09/21/2007] [Accepted: 10/01/2007] [Indexed: 11/30/2022]
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Scherer D, Kiesecker C, Kulzer M, Günth M, Scholz EP, Kathöfer S, Thomas D, Maurer M, Kreuzer J, Bauer A, Katus HA, Karle CA, Zitron E. Activation of inwardly rectifying Kir2.x potassium channels by beta 3-adrenoceptors is mediated via different signaling pathways with a predominant role of PKC for Kir2.1 and of PKA for Kir2.2. Naunyn Schmiedebergs Arch Pharmacol 2007; 375:311-22. [PMID: 17534603 DOI: 10.1007/s00210-007-0167-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2006] [Accepted: 05/07/2007] [Indexed: 01/22/2023]
Abstract
beta(3)-adrenoceptors have recently been shown to induce a complex modulation of intracellular signaling pathways including cyclic guanine monophosphate, cyclic adenosine monophosphate, nitric oxide, and protein kinases A and C. They are expressed in a broad variety of tissues including the myocardium, vascular smooth muscle, and endothelium. In those tissues, resting membrane potential is controlled mainly by inwardly rectifying potassium channels of the Kir2 family namely, Kir2.1 in the vascular smooth muscle, Kir2.1-2.3 in the myocardium, and Kir2.1-2.2 in the endothelium. In the present study, we investigated the possible modulation of Kir2 channel function by beta(3)-adrenoceptors in an expression system. Human-cloned beta(3)-adrenoceptors and Kir2.1 (KCNJ2), Kir2.2 (KCNJ12), and Kir2.3 (KCNJ4) channels were coexpressed in Xenopus oocytes, and currents were measured with double-microelectrode voltage clamp. Activation of beta(3)-adrenoceptors with isoproterenol resulted in markedly increased currents in Kir2.1 and in Kir2.2 potassium channels with EC50 values of 27 and 18 nM, respectively. In contrast, Kir2.3 currents were not modulated. Coapplication of specific inhibitors of protein kinase A (KT-5720) and calmodulin kinase II (KN-93) had no effects on the observed regulation in Kir2.1. However, coapplication of protein kinase C (PKC) inhibitors staurosporine and chelerythrine suppressed the observed effect. In Kir2.2, coapplication of KT-5720 reduced the effect of beta(3)-adrenoceptor activation. No differences in current increase after application of isoproterenol were observed between mutant Kir2.2 potassium channels lacking all functional PKC phosphorylation sites and Kir2.2 wild-type channels. In heteromeric Kir2.x channels, all types of heteromers were activated. The effect was most pronounced in Kir2.1/Kir2.2 and in Kir2.2/Kir2.3 channels. In summary, homomeric and heteromeric Kir2.x channels are activated by beta(3)-adrenoceptors via different protein kinase-dependent pathways: Kir2.1 subunits are modulated by PKC, whereas Kir2.2 is modulated by protein kinase A. In heteromeric composition, a marked activation of currents can be observed particularly with involvement of Kir2.2 subunits. This regulation may contribute to the hyperpolarizing effects of beta(3)-adrenoceptors in tissues that exhibit modulation by Kir2 channel function.
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Affiliation(s)
- Daniel Scherer
- Department of Cardiology, Medical University Hospital Heidelberg, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany
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Zhang W, Zitron E, Hömme M, Kihm L, Morath C, Scherer D, Hegge S, Thomas D, Schmitt CP, Zeier M, Katus H, Karle C, Schwenger V. Aquaporin-1 channel function is positively regulated by protein kinase C. J Biol Chem 2007; 282:20933-40. [PMID: 17522053 DOI: 10.1074/jbc.m703858200] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Aquaporin-1 (AQP1) channels contribute to osmotically induced water transport in several organs including the kidney and serosal membranes such as the peritoneum and the pleura. In addition, AQP1 channels have been shown to conduct cationic currents upon stimulation by cyclic nucleotides. To date, the short term regulation of AQP1 function by other major intracellular signaling pathways has not been studied. In the present study, we therefore investigated the regulation of AQP1 by protein kinase C. AQP1 wild type channels were expressed in Xenopus oocytes. Water permeability was assessed by hypotonic challenges. Activation of protein kinase C (PKC) by 1-oleoyl-2-acetyl-sn-glycerol (OAG) induced a marked increase of AQP1-dependent water permeability. This regulation was abolished in mutated AQP1 channels lacking both consensus PKC phosphorylation sites Thr(157) and Thr(239) (termed AQP1 DeltaPKC). AQP1 cationic currents measured with double-electrode voltage clamp were markedly increased after pharmacological activation of PKC by either OAG or phorbol 12-myristate 13-acetate. Deletion of either Thr(157) or Thr(239) caused a marked attenuation of PKC-dependent current increases, and deletion of both phosphorylation sites in AQP1 DeltaPKC channels abolished the effect. In vitro phosphorylation studies with synthesized peptides corresponding to amino acids 154-168 and 236-250 revealed that both Thr(157) and Thr(239) are phosphorylated by PKC. Upon stimulation by cyclic nucleotides, AQP1 wild type currents exhibited a strong activation. This regulation was not affected after deletion of PKC phosphorylation sites in AQP1 DeltaPKC channels. In conclusion, this is the first study to show that PKC positively regulates both water permeability and ionic conductance of AQP1 channels. This new pathway of AQP1 regulation is independent of the previously described cyclic nucleotide pathway and may contribute to the PKC stimulation of AQP1-modulated processes such as endothelial permeability, angiogenesis, and urine concentration.
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Affiliation(s)
- Wei Zhang
- Department of Cardiology, University Hospital Heidelberg, D-69120 Heidelberg, Germany
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