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Zhong L, Yan Z, Jiang D, Weng KC, Ouyang Y, Zhang H, Lin X, Xiao C, Yang H, Yao J, Kang X, Wang C, Huang C, Shen B, Chung SK, Jiang ZH, Zhu W, Neher E, Silva JR, Hou P. Targeting the I Ks Channel PKA Phosphorylation Axis to Restore Its Function in High-Risk LQT1 Variants. Circ Res 2024; 135:722-738. [PMID: 39166328 PMCID: PMC11392204 DOI: 10.1161/circresaha.124.325009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2024] [Revised: 08/05/2024] [Accepted: 08/09/2024] [Indexed: 08/22/2024]
Abstract
BACKGROUND The KCNQ1+KCNE1 (IKs) potassium channel plays a crucial role in cardiac adaptation to stress, in which β-adrenergic stimulation phosphorylates the IKs channel through the cyclic adenosine monophosphate (cAMP)/PKA (protein kinase A) pathway. Phosphorylation increases the channel current and accelerates repolarization to adapt to an increased heart rate. Variants in KCNQ1 can cause long-QT syndrome type 1 (LQT1), and those with defective cAMP effects predispose patients to the highest risk of cardiac arrest and sudden death. However, the molecular connection between IKs channel phosphorylation and channel function, as well as why high-risk LQT1 mutations lose cAMP sensitivity, remain unclear. METHODS Regular patch clamp and voltage clamp fluorometry techniques were utilized to record pore opening and voltage sensor movement of wild-type and mutant KCNQ1/IKs channels. The clinical phenotypic penetrance of each LQT1 mutation was analyzed as a metric for assessing their clinical risk. The patient-specific-induced pluripotent stem-cell model was used to test mechanistic findings in physiological conditions. RESULTS By systematically elucidating mechanisms of a series of LQT1 variants that lack cAMP sensitivity, we identified molecular determinants of IKs channel regulation by phosphorylation. These key residues are distributed across the N-terminus of KCNQ1 extending to the central pore region of IKs. We refer to this pattern as the IKs channel PKA phosphorylation axis. Next, by examining LQT1 variants from clinical databases containing 10 579 LQT1 carriers, we found that the distribution of the most high-penetrance LQT1 variants extends across the IKs channel PKA phosphorylation axis, demonstrating its clinical relevance. Furthermore, we found that a small molecule, ML277, which binds at the center of the phosphorylation axis, rescues the defective cAMP effects of multiple high-risk LQT1 variants. This finding was then tested in high-risk patient-specific induced pluripotent stem cell-derived cardiomyocytes, where ML277 remarkably alleviates the beating abnormalities. CONCLUSIONS Our findings not only elucidate the molecular mechanism of PKA-dependent IKs channel phosphorylation but also provide an effective antiarrhythmic strategy for patients with high-risk LQT1 variants.
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Affiliation(s)
- Ling Zhong
- Dr. Neher's Biophysics Laboratory for Innovative Drug Discovery, State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Taipa, Macao SAR, China (L.Z., Z.Y., D.J., Y.O., H.Z., X.L., C.X., C.H., B.S., S.K.C., Z.-H.J., E.N., P.H.)
- Macau University of Science and Technology Zhuhai MUST Science and Technology Research Institute. Zhuhai, Guangdong, China (L.Z., Z.Y., D.J., Y.O., H.Z., X.L., C.X., C.H., B.S., S.K.C., Z.-H.J., E.N., P.H.)
| | - Zhenzhen Yan
- Dr. Neher's Biophysics Laboratory for Innovative Drug Discovery, State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Taipa, Macao SAR, China (L.Z., Z.Y., D.J., Y.O., H.Z., X.L., C.X., C.H., B.S., S.K.C., Z.-H.J., E.N., P.H.)
- Macau University of Science and Technology Zhuhai MUST Science and Technology Research Institute. Zhuhai, Guangdong, China (L.Z., Z.Y., D.J., Y.O., H.Z., X.L., C.X., C.H., B.S., S.K.C., Z.-H.J., E.N., P.H.)
| | - Dexiang Jiang
- Dr. Neher's Biophysics Laboratory for Innovative Drug Discovery, State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Taipa, Macao SAR, China (L.Z., Z.Y., D.J., Y.O., H.Z., X.L., C.X., C.H., B.S., S.K.C., Z.-H.J., E.N., P.H.)
- Macau University of Science and Technology Zhuhai MUST Science and Technology Research Institute. Zhuhai, Guangdong, China (L.Z., Z.Y., D.J., Y.O., H.Z., X.L., C.X., C.H., B.S., S.K.C., Z.-H.J., E.N., P.H.)
| | - Kuo-Chan Weng
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO (K.-C.W., J.R.S.)
| | - Yue Ouyang
- Dr. Neher's Biophysics Laboratory for Innovative Drug Discovery, State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Taipa, Macao SAR, China (L.Z., Z.Y., D.J., Y.O., H.Z., X.L., C.X., C.H., B.S., S.K.C., Z.-H.J., E.N., P.H.)
- Macau University of Science and Technology Zhuhai MUST Science and Technology Research Institute. Zhuhai, Guangdong, China (L.Z., Z.Y., D.J., Y.O., H.Z., X.L., C.X., C.H., B.S., S.K.C., Z.-H.J., E.N., P.H.)
| | - Hangyu Zhang
- Dr. Neher's Biophysics Laboratory for Innovative Drug Discovery, State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Taipa, Macao SAR, China (L.Z., Z.Y., D.J., Y.O., H.Z., X.L., C.X., C.H., B.S., S.K.C., Z.-H.J., E.N., P.H.)
- Macau University of Science and Technology Zhuhai MUST Science and Technology Research Institute. Zhuhai, Guangdong, China (L.Z., Z.Y., D.J., Y.O., H.Z., X.L., C.X., C.H., B.S., S.K.C., Z.-H.J., E.N., P.H.)
| | - Xiaoqing Lin
- Dr. Neher's Biophysics Laboratory for Innovative Drug Discovery, State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Taipa, Macao SAR, China (L.Z., Z.Y., D.J., Y.O., H.Z., X.L., C.X., C.H., B.S., S.K.C., Z.-H.J., E.N., P.H.)
- Macau University of Science and Technology Zhuhai MUST Science and Technology Research Institute. Zhuhai, Guangdong, China (L.Z., Z.Y., D.J., Y.O., H.Z., X.L., C.X., C.H., B.S., S.K.C., Z.-H.J., E.N., P.H.)
| | - Chenxin Xiao
- Dr. Neher's Biophysics Laboratory for Innovative Drug Discovery, State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Taipa, Macao SAR, China (L.Z., Z.Y., D.J., Y.O., H.Z., X.L., C.X., C.H., B.S., S.K.C., Z.-H.J., E.N., P.H.)
- Macau University of Science and Technology Zhuhai MUST Science and Technology Research Institute. Zhuhai, Guangdong, China (L.Z., Z.Y., D.J., Y.O., H.Z., X.L., C.X., C.H., B.S., S.K.C., Z.-H.J., E.N., P.H.)
| | - Huaiyu Yang
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University (H.Y.)
| | - Jing Yao
- State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, TaiKang Center for Life and Medical Sciences, Frontier Science Center for Immunology and Metabolism, Wuhan University, China (J.Y.)
| | - Xinjiang Kang
- Key Laboratory of Medical Electrophysiology, Ministry of Education of China, Collaborative Innovation Center for Prevention and Treatment of Cardiovascular Disease and the Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China (X.K.)
- Department of Neurosurgery, the Affiliated Hospital of Southwest Medical University, Luzhou, China (X.K.)
- College of Life Sciences, Liaocheng University, China (X.K.)
| | - Changhe Wang
- Dr. Neher's Biophysics Laboratory for Innovative Drug Discovery, State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Taipa, Macao SAR, China (L.Z., Z.Y., D.J., Y.O., H.Z., X.L., C.X., C.H., B.S., S.K.C., Z.-H.J., E.N., P.H.)
- Department of Neurology, First Affiliated Hospital, Neuroscience Research Center, Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, China (C.W.)
| | - Chen Huang
- Macau University of Science and Technology Zhuhai MUST Science and Technology Research Institute. Zhuhai, Guangdong, China (L.Z., Z.Y., D.J., Y.O., H.Z., X.L., C.X., C.H., B.S., S.K.C., Z.-H.J., E.N., P.H.)
| | - Bing Shen
- Dr. Neher's Biophysics Laboratory for Innovative Drug Discovery, State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Taipa, Macao SAR, China (L.Z., Z.Y., D.J., Y.O., H.Z., X.L., C.X., C.H., B.S., S.K.C., Z.-H.J., E.N., P.H.)
- Macau University of Science and Technology Zhuhai MUST Science and Technology Research Institute. Zhuhai, Guangdong, China (L.Z., Z.Y., D.J., Y.O., H.Z., X.L., C.X., C.H., B.S., S.K.C., Z.-H.J., E.N., P.H.)
| | - Sookja Kim Chung
- Dr. Neher's Biophysics Laboratory for Innovative Drug Discovery, State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Taipa, Macao SAR, China (L.Z., Z.Y., D.J., Y.O., H.Z., X.L., C.X., C.H., B.S., S.K.C., Z.-H.J., E.N., P.H.)
- Macau University of Science and Technology Zhuhai MUST Science and Technology Research Institute. Zhuhai, Guangdong, China (L.Z., Z.Y., D.J., Y.O., H.Z., X.L., C.X., C.H., B.S., S.K.C., Z.-H.J., E.N., P.H.)
| | - Zhi-Hong Jiang
- Dr. Neher's Biophysics Laboratory for Innovative Drug Discovery, State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Taipa, Macao SAR, China (L.Z., Z.Y., D.J., Y.O., H.Z., X.L., C.X., C.H., B.S., S.K.C., Z.-H.J., E.N., P.H.)
- Macau University of Science and Technology Zhuhai MUST Science and Technology Research Institute. Zhuhai, Guangdong, China (L.Z., Z.Y., D.J., Y.O., H.Z., X.L., C.X., C.H., B.S., S.K.C., Z.-H.J., E.N., P.H.)
| | - Wandi Zhu
- Cardiovascular Medicine Division and Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA (W.Z.)
| | - Erwin Neher
- Dr. Neher's Biophysics Laboratory for Innovative Drug Discovery, State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Taipa, Macao SAR, China (L.Z., Z.Y., D.J., Y.O., H.Z., X.L., C.X., C.H., B.S., S.K.C., Z.-H.J., E.N., P.H.)
- Macau University of Science and Technology Zhuhai MUST Science and Technology Research Institute. Zhuhai, Guangdong, China (L.Z., Z.Y., D.J., Y.O., H.Z., X.L., C.X., C.H., B.S., S.K.C., Z.-H.J., E.N., P.H.)
| | - Jonathan R Silva
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO (K.-C.W., J.R.S.)
| | - Panpan Hou
- Dr. Neher's Biophysics Laboratory for Innovative Drug Discovery, State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Taipa, Macao SAR, China (L.Z., Z.Y., D.J., Y.O., H.Z., X.L., C.X., C.H., B.S., S.K.C., Z.-H.J., E.N., P.H.)
- Macau University of Science and Technology Zhuhai MUST Science and Technology Research Institute. Zhuhai, Guangdong, China (L.Z., Z.Y., D.J., Y.O., H.Z., X.L., C.X., C.H., B.S., S.K.C., Z.-H.J., E.N., P.H.)
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Avalos-Hernandez A, Juarez-Navarro K, Ruiz-Baca E, Meneses-Morales I, Espino-Saldaña E, Martinez-Torres A, Lopez-Rodriguez A. Unlocking cellular traffic jams: olive oil-mediated rescue of CNG mutant channels. Front Pharmacol 2024; 15:1408156. [PMID: 39119605 PMCID: PMC11306028 DOI: 10.3389/fphar.2024.1408156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Accepted: 06/28/2024] [Indexed: 08/10/2024] Open
Abstract
One of the reasons to suggest olive oil consumption for a healthy life is its potential to induce robust lipidomic remodeling through membrane modification by dietary lipids. This remodeling might, in turn, modulate essential lipid-protein interactions while maintaining accurate transmembrane protein/domain orientation. Oleic acid, the primary compound in olive oil, has been suggested as a modulator of ion channel function. In this study, we explored whether this lipid could rescue the trafficking of mutated transmembrane proteins. In our initial approach, we supplemented the cell culture medium of HEK-293 cells expressing cyclic nucleotide channels tagged using green fluorescent protein (CNG-GFP) with olive oil or oleic acid. In addition to wild-type channels, we also expressed R272Q and R278W mutant channels, two non-functional intracellularly retained channels related to retinopathies. We used fluorescence microscopy and patch-clamp in the inside-out configuration to assess changes in the cell localization and function of the tested channels. Our results demonstrated that olive oil and oleic acid facilitated the transport of cyclic nucleotide-gated R272Q mutant channels towards the plasma membrane, rendering them electrophysiologically functional. Thus, our findings reveal a novel property of olive oil as a membrane protein traffic inductor.
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Affiliation(s)
| | - Karina Juarez-Navarro
- Facultad de Ciencias Químicas, Universidad Juárez del Estado de Durango, Durango, Mexico
| | - Estela Ruiz-Baca
- Facultad de Ciencias Químicas, Universidad Juárez del Estado de Durango, Durango, Mexico
| | - Ivan Meneses-Morales
- Facultad de Ciencias Químicas, Universidad Juárez del Estado de Durango, Durango, Mexico
| | - Edith Espino-Saldaña
- Laboratorio de Neurobiología Molecular y Celular, Instituto de Neurobiología, Universidad Nacional Autónoma de México. Campus Juriquilla, Juriquilla, Mexico
| | - Ataulfo Martinez-Torres
- Laboratorio de Neurobiología Molecular y Celular, Instituto de Neurobiología, Universidad Nacional Autónoma de México. Campus Juriquilla, Juriquilla, Mexico
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3
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Roy-Chowdhury S, Jang S, Abderemane-Ali F, Naughton F, Grabe M, Minor DL. Structure of the human K 2P13.1(THIK-1) channel reveals a novel hydrophilic pore restriction and lipid cofactor site. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.26.600491. [PMID: 38979306 PMCID: PMC11230452 DOI: 10.1101/2024.06.26.600491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
The halothane-inhibited K2P leak potassium channel K2P13.1 (THIK-1)1-3 is found in diverse cells1,4 including neurons1,5 and microglia6-8 where it affects surveillance6, synaptic pruning7, phagocytosis7, and inflammasome-mediated interleukin-1β release6,8,9. As with many K2Ps1,5,10-14 and other voltage-gated ion channel (VGIC) superfamily members3,15,16, polyunsaturated fatty acid (PUFA) lipids modulate K2P13.1 (THIK-1)1,5,14,17 via a poorly understood mechanism. Here, we present cryo-electronmicroscopy (cryo-EM) structures of human K2P13.1 (THIK-1) and mutants in lipid nanodiscs and detergent. These reveal that, unlike other K2Ps13,18-24, K2P13.1 (THIK-1) has a two-chamber aqueous inner cavity obstructed by a M4 transmembrane helix tyrosine (Tyr273, the flow restrictor). This hydrophilic barrier can be opened by an activatory mutation, S136P25, at natural break in the M2 transmembrane helix and by intrinsic channel dynamics. The structures also reveal a buried lipid in the P1/M4 intersubunit interface at a location, the PUFA site, that coincides with the TREK subfamily K2P modulator pocket for small molecule agonists18,26,27. This overlap, together with the effects of mutation on K2P13.1 (THIK-1) PUFA responses, indicates that the PUFA site lipids are K2P13.1 (THIK-1) cofactors. Comparison with the PUFA-responsive VGIC Kv7.1 (KCNQ1)28-31 reveals a shared role for the equivalent pore domain intersubunit interface in lipid modulation, providing a framework for dissecting the effects of PUFAs on the VGIC superfamily. Our findings reveal the unique architecture underlying K2P13.1 (THIK-1) function, highlight the importance of the P1/M4 interface in control of K2Ps by both natural and synthetic agents, and should aid development of THIK subfamily modulators for diseases such as neuroinflammation6,32 and autism6.
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Affiliation(s)
- Shatabdi Roy-Chowdhury
- Cardiovascular Research Institute, University of California, San Francisco, California 93858-2330 USA
| | - Seil Jang
- Cardiovascular Research Institute, University of California, San Francisco, California 93858-2330 USA
| | - Fayal Abderemane-Ali
- Cardiovascular Research Institute, University of California, San Francisco, California 93858-2330 USA
| | - Fiona Naughton
- Cardiovascular Research Institute, University of California, San Francisco, California 93858-2330 USA
| | - Michael Grabe
- Cardiovascular Research Institute, University of California, San Francisco, California 93858-2330 USA
- Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, California 93858-2330 USA
| | - Daniel L. Minor
- Cardiovascular Research Institute, University of California, San Francisco, California 93858-2330 USA
- Departments of Biochemistry and Biophysics, and Cellular and Molecular Pharmacology, University of California, San Francisco, California 93858-2330 USA
- California Institute for Quantitative Biomedical Research, University of California, San Francisco, California 93858-2330 USA
- Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, California 93858-2330 USA
- Molecular Biophysics and Integrated Bio-imaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
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Jowais JJ, Yazdi S, Golluscio A, Olivier-Meo V, Liin SI, Larsson HP. Mechanistic understanding of KCNQ1 activating polyunsaturated fatty acid analogs. J Gen Physiol 2023; 155:e202313339. [PMID: 37526928 PMCID: PMC10394376 DOI: 10.1085/jgp.202313339] [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: 01/12/2023] [Revised: 05/02/2023] [Accepted: 07/18/2023] [Indexed: 08/02/2023] Open
Abstract
The KCNQ1 channel is important for the repolarization phase of the cardiac action potential. Loss of function mutations in KCNQ1 can cause long QT syndrome (LQTS), which can lead to cardiac arrythmia and even sudden cardiac death. We have previously shown that polyunsaturated fatty acids (PUFAs) and PUFA analogs can activate the cardiac KCNQ1 channel, making them potential therapeutics for the treatment of LQTS. PUFAs bind to KCNQ1 at two different binding sites: one at the voltage sensor (Site I) and one at the pore (Site II). PUFA interaction at Site I shifts the voltage dependence of the channel to the left, while interaction at Site II increases maximal conductance. The PUFA analogs, linoleic-glycine and linoleic-tyrosine, are more effective than linoleic acid at Site I, but less effective at Site II. Using both simulations and experiments, we find that the larger head groups of linoleic-glycine and linoleic-tyrosine interact with more residues than the smaller linoleic acid at Site I. We propose that this will stabilize the negatively charged PUFA head group in a position to better interact electrostatically with the positively charges in the voltage sensor. In contrast, the larger head groups of linoleic-glycine and linoleic-tyrosine compared with linoleic acid prevent a close fit of these PUFA analogs in Site II, which is more confined. In addition, we identify several KCNQ1 residues as critical PUFA-analog binding residues, thereby providing molecular models of specific interactions between PUFA analogs and KCNQ1. These interactions will aid in future drug development based on PUFA-KCNQ1 channel interactions.
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Affiliation(s)
- Jessica J. Jowais
- Department of Physiology and Biophysics, University of Miami, Miami, FL, USA
| | - Samira Yazdi
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Alessia Golluscio
- Department of Physiology and Biophysics, University of Miami, Miami, FL, USA
| | - Vanessa Olivier-Meo
- Department of Physiology and Biophysics, University of Miami, Miami, FL, USA
| | - Sara I. Liin
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - H. Peter Larsson
- Department of Physiology and Biophysics, University of Miami, Miami, FL, USA
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De la Cruz A, Wu X, Rainer QC, Hiniesto-Iñigo I, Perez ME, Edler I, Liin SI, Larsson HP. Pharmacological Screening of Kv7.1 and Kv7.1/KCNE1 Activators as Potential Antiarrhythmic Drugs in the Zebrafish Heart. Int J Mol Sci 2023; 24:12092. [PMID: 37569465 PMCID: PMC10418701 DOI: 10.3390/ijms241512092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 07/24/2023] [Accepted: 07/25/2023] [Indexed: 08/13/2023] Open
Abstract
Long QT syndrome (LQTS) can lead to ventricular arrhythmia and sudden cardiac death. The most common congenital cause of LQTS is mutations in the channel subunits generating the cardiac potassium current IKs. Zebrafish (Danio rerio) have been proposed as a powerful system to model human cardiac diseases due to the similar electrical properties of the zebrafish heart and the human heart. We used high-resolution all-optical electrophysiology on ex vivo zebrafish hearts to assess the effects of IKs analogues on the cardiac action potential. We found that chromanol 293B (an IKs inhibitor) prolonged the action potential duration (APD) in the presence of E4031 (an IKr inhibitor applied to drug-induced LQT2), and to a lesser extent, in the absence of E4031. Moreover, we showed that PUFA analogues slightly shortened the APD of the zebrafish heart. However, PUFA analogues failed to reverse the APD prolongation in drug-induced LQT2. However, a more potent IKs activator, ML-277, partially reversed the APD prolongation in drug-induced LQT2 zebrafish hearts. Our results suggest that IKs plays a limited role in ventricular repolarizations in the zebrafish heart under resting conditions, although it plays a more important role when the IKr is compromised, as if the IKs in zebrafish serves as a repolarization reserve as in human hearts. This study shows that potent IKs activators can restore the action potential duration in drug-induced LQT2 in the zebrafish heart.
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Affiliation(s)
- Alicia De la Cruz
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, 1600 NW 10th Avenue, Miami, FL 33136, USA
| | - Xiaoan Wu
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, 1600 NW 10th Avenue, Miami, FL 33136, USA
| | - Quinn C. Rainer
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, 1600 NW 10th Avenue, Miami, FL 33136, USA
| | - Irene Hiniesto-Iñigo
- Department of Biomedical and Clinical Sciences, Linköping University, SE-581 85 Linköping, Sweden
| | - Marta E. Perez
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, 1600 NW 10th Avenue, Miami, FL 33136, USA
| | - Isak Edler
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, 1600 NW 10th Avenue, Miami, FL 33136, USA
- Department of Biomedical and Clinical Sciences, Linköping University, SE-581 85 Linköping, Sweden
| | - Sara I. Liin
- Department of Biomedical and Clinical Sciences, Linköping University, SE-581 85 Linköping, Sweden
| | - H. Peter Larsson
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, 1600 NW 10th Avenue, Miami, FL 33136, USA
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6
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Hiniesto-Iñigo I, Castro-Gonzalez LM, Corradi V, Skarsfeldt MA, Yazdi S, Lundholm S, Nikesjö J, Noskov SY, Bentzen BH, Tieleman DP, Liin SI. Endocannabinoids enhance hK V7.1/KCNE1 channel function and shorten the cardiac action potential and QT interval. EBioMedicine 2023; 89:104459. [PMID: 36796231 PMCID: PMC9958262 DOI: 10.1016/j.ebiom.2023.104459] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 01/11/2023] [Accepted: 01/18/2023] [Indexed: 02/15/2023] Open
Abstract
BACKGROUND Genotype-positive patients who suffer from the cardiac channelopathy Long QT Syndrome (LQTS) may display a spectrum of clinical phenotypes, with often unknown causes. Therefore, there is a need to identify factors influencing disease severity to move towards an individualized clinical management of LQTS. One possible factor influencing the disease phenotype is the endocannabinoid system, which has emerged as a modulator of cardiovascular function. In this study, we aim to elucidate whether endocannabinoids target the cardiac voltage-gated potassium channel KV7.1/KCNE1, which is the most frequently mutated ion channel in LQTS. METHODS We used two-electrode voltage clamp, molecular dynamics simulations and the E4031 drug-induced LQT2 model of ex-vivo guinea pig hearts. FINDINGS We found a set of endocannabinoids that facilitate channel activation, seen as a shifted voltage-dependence of channel opening and increased overall current amplitude and conductance. We propose that negatively charged endocannabinoids interact with known lipid binding sites at positively charged amino acids on the channel, providing structural insights into why only specific endocannabinoids modulate KV7.1/KCNE1. Using the endocannabinoid ARA-S as a prototype, we show that the effect is not dependent on the KCNE1 subunit or the phosphorylation state of the channel. In guinea pig hearts, ARA-S was found to reverse the E4031-prolonged action potential duration and QT interval. INTERPRETATION We consider the endocannabinoids as an interesting class of hKV7.1/KCNE1 channel modulators with putative protective effects in LQTS contexts. FUNDING ERC (No. 850622), Canadian Institutes of Health Research, Canada Research Chairs and Compute Canada, Swedish National Infrastructure for Computing.
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Affiliation(s)
- Irene Hiniesto-Iñigo
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Laura M Castro-Gonzalez
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Valentina Corradi
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Mark A Skarsfeldt
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Samira Yazdi
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Siri Lundholm
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Johan Nikesjö
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Sergei Yu Noskov
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Bo Hjorth Bentzen
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - D Peter Tieleman
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Sara I Liin
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden.
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7
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Bohannon BM, Jowais JJ, Nyberg L, Liin SI, Larsson HP. Mechanistic insights into robust cardiac I Ks potassium channel activation by aromatic polyunsaturated fatty acid analogues. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.12.523777. [PMID: 36711783 PMCID: PMC9882137 DOI: 10.1101/2023.01.12.523777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Voltage-gated potassium (K V ) channels are important regulators of cellular excitability and control action potential repolarization in the heart and brain. K V channel mutations lead to disordered cellular excitability. Loss-of-function mutations, for example, result in membrane hyperexcitability, a characteristic of epilepsy and cardiac arrhythmias. Interventions intended to restore K V channel function have strong therapeutic potential in such disorders. Polyunsaturated fatty acids (PUFAs) and PUFA analogues comprise a class of K V channel activators with potential applications in the treatment of arrhythmogenic disorders such as Long QT Syndrome (LQTS). LQTS is caused by a loss-of-function of the cardiac I Ks channel - a tetrameric potassium channel complex formed by K V 7.1 and associated KCNE1 protein subunits. We have discovered a set of aromatic PUFA analogues that produce robust activation of the cardiac I Ks channel and a unique feature of these PUFA analogues is an aromatic, tyrosine head group. We determine the mechanisms through which tyrosine PUFA analogues exert strong activating effects on the I Ks channel by generating modified aromatic head groups designed to probe cation-pi interactions, hydrogen bonding, and ionic interactions. We found that tyrosine PUFA analogues do not activate the I Ks channel through cation-pi interactions, but instead do so through a combination of hydrogen bonding and ionic interactions.
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Affiliation(s)
- Briana M. Bohannon
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
| | - Jessica J. Jowais
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
| | - Leif Nyberg
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, FL 33136, USA,Department of Biomedical and Clinical Sciences, Linköping University, SE-581 85 Linköping, Sweden
| | - Sara I. Liin
- Department of Biomedical and Clinical Sciences, Linköping University, SE-581 85 Linköping, Sweden
| | - H. Peter Larsson
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
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8
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Liin SI. ASIC3, a proton-gated ion channel with preference for polyunsaturated lipids with specific headgroup and tail properties. J Gen Physiol 2022; 154:e202213171. [PMID: 35583814 PMCID: PMC9121178 DOI: 10.1085/jgp.202213171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Commentary highlighting valuable mechanistic insights provided by Klipp and Bankston on ASIC3 regulation by lipids.
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Affiliation(s)
- Sara I. Liin
- Department of Biomedical and Clinical Sciences, Division of Neurobiology, Linköping University, Linköping, Sweden
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9
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Klipp RC, Bankston JR. Structural determinants of acid-sensing ion channel potentiation by single chain lipids. J Gen Physiol 2022; 154:e202213156. [PMID: 35583813 PMCID: PMC9120901 DOI: 10.1085/jgp.202213156] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 05/02/2022] [Indexed: 01/07/2023] Open
Abstract
Acid-sensing ion channels (ASICs) are sensitized to activation by inflammatory mediators such as the polyunsaturated fatty acid (PUFA) arachidonic acid (AA). Previous work has shown that AA can potentiate ASIC currents at subsaturating proton concentrations, but the structural mechanisms of this change in gating are not understood. Here we show that PUFAs cause multiple gating changes in ASIC3, including shifting the pH dependence of activation, slowing the rate of desensitization, and increasing the current even at a saturating pH. The impact on gating depends on the nature of both the head and tail of the lipid, with the head group structure primarily determining the magnitude of the effect on the channel. An N-acyl amino acid (NAAA), arachidonyl glycine (AG), is such a strong regulator that it can act as a ligand at neutral pH. Mutation of an arginine in the outer segment of TM1 (R64) eliminated the effect of docosahexaenoic acid (DHA) even at high concentrations, suggesting a potential interaction site for the lipid on the channel. Our results suggest a model in which PUFAs bind to ASICs via both their tail group and an electrostatic interaction between the negatively charged PUFA head group and the positively charged arginine side chain. These data provide the first look at the structural features of lipids that are important for modulating ASICs and suggest a potential binding site for PUFAs on the channel.
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Affiliation(s)
- Robert C. Klipp
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - John R. Bankston
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO
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10
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Frampton DJA, Choudhury K, Nikesjö J, Delemotte L, Liin SI. Subtype-specific responses of hKv7.4 and hKv7.5 channels to polyunsaturated fatty acids reveal an unconventional modulatory site and mechanism. eLife 2022; 11:77672. [PMID: 35642964 PMCID: PMC9159753 DOI: 10.7554/elife.77672] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 05/11/2022] [Indexed: 11/13/2022] Open
Abstract
The KV7.4 and KV7.5 subtypes of voltage-gated potassium channels play a role in important physiological processes such as sound amplification in the cochlea and adjusting vascular smooth muscle tone. Therefore, the mechanisms that regulate KV7.4 and KV7.5 channel function are of interest. Here, we study the effect of polyunsaturated fatty acids (PUFAs) on human KV7.4 and KV7.5 channels expressed in Xenopus oocytes. We report that PUFAs facilitate activation of hKV7.5 by shifting the V50 of the conductance versus voltage (G(V)) curve toward more negative voltages. This response depends on the head group charge, as an uncharged PUFA analogue has no effect and a positively charged PUFA analogue induces positive V50 shifts. In contrast, PUFAs inhibit activation of hKV7.4 by shifting V50 toward more positive voltages. No effect on V50 of hKV7.4 is observed by an uncharged or a positively charged PUFA analogue. Thus, the hKV7.5 channel's response to PUFAs is analogous to the one previously observed in hKV7.1-7.3 channels, whereas the hKV7.4 channel response is opposite, revealing subtype-specific responses to PUFAs. We identify a unique inner PUFA interaction site in the voltage-sensing domain of hKV7.4 underlying the PUFA response, revealing an unconventional mechanism of modulation of hKV7.4 by PUFAs.
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Affiliation(s)
- Damon J A Frampton
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Koushik Choudhury
- Science for Life Laboratory, Department of Applied Physics, KTH Royal Institute of Technology, Solna, Sweden
| | - Johan Nikesjö
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Lucie Delemotte
- Science for Life Laboratory, Department of Applied Physics, KTH Royal Institute of Technology, Solna, Sweden
| | - Sara I Liin
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
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11
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Castiglione A, Hornyik T, Wülfers EM, Giammarino L, Edler I, Jowais JJ, Rieder M, Perez-Feliz S, Koren G, Bősze Z, Varró A, Zehender M, Brunner M, Bode C, Liin SI, Larsson HP, Baczkó I, Odening KE. Docosahexaenoic acid normalizes QT interval in long QT type 2 transgenic rabbit models in a genotype-specific fashion. Europace 2022; 24:511-522. [PMID: 34601592 PMCID: PMC9125797 DOI: 10.1093/europace/euab228] [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: 06/02/2021] [Accepted: 08/11/2021] [Indexed: 11/13/2022] Open
Abstract
AIM Long QT syndrome (LQTS) is a cardiac channelopathy predisposing to ventricular arrhythmias and sudden cardiac death. Since current therapies often fail to prevent arrhythmic events in certain LQTS subtypes, new therapeutic strategies are needed. Docosahexaenoic acid (DHA) is a polyunsaturated fatty acid, which enhances the repolarizing IKs current. METHODS AND RESULTS We investigated the effects of DHA in wild type (WT) and transgenic long QT Type 1 (LQT1; loss of IKs), LQT2 (loss of IKr), LQT5 (reduction of IKs), and LQT2-5 (loss of IKr and reduction of IKs) rabbits. In vivo ECGs were recorded at baseline and after 10 µM/kg DHA to assess changes in heart-rate corrected QT (QTc) and short-term variability of QT (STVQT). Ex vivo monophasic action potentials were recorded in Langendorff-perfused rabbit hearts, and action potential duration (APD75) and triangulation were assessed. Docosahexaenoic acid significantly shortened QTc in vivo only in WT and LQT2 rabbits, in which both α- and β-subunits of IKs-conducting channels are functionally intact. In LQT2, this led to a normalization of QTc and of its short-term variability. Docosahexaenoic acid had no effect on QTc in LQT1, LQT5, and LQT2-5. Similarly, ex vivo, DHA shortened APD75 in WT and normalized it in LQT2, and additionally decreased AP triangulation in LQT2. CONCLUSIONS Docosahexaenoic acid exerts a genotype-specific beneficial shortening/normalizing effect on QTc and APD75 and reduces pro-arrhythmia markers STVQT and AP triangulation through activation of IKs in LQT2 rabbits but has no effects if either α- or β-subunits to IKs are functionally impaired. Docosahexaenoic acid could represent a new genotype-specific therapy in LQT2.
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Affiliation(s)
- Alessandro Castiglione
- Department of Cardiology and Angiology I, University Heart Center Freiburg, Medical Faculty, University of Freiburg, Freiburg, Germany
- Translational Cardiology, Department of Cardiology, Inselspital, Bern University Hospital, University of Bern, Buehlplatz 5, CH-3012 Bern, Switzerland
- Department of Translational Cardiology/Electrophysiology, Institute of Physiology, University of Bern, Bern, Switzerland
| | - Tibor Hornyik
- Department of Cardiology and Angiology I, University Heart Center Freiburg, Medical Faculty, University of Freiburg, Freiburg, Germany
- Translational Cardiology, Department of Cardiology, Inselspital, Bern University Hospital, University of Bern, Buehlplatz 5, CH-3012 Bern, Switzerland
- Department of Translational Cardiology/Electrophysiology, Institute of Physiology, University of Bern, Bern, Switzerland
- Institute of Experimental Cardiovascular Medicine, University Heart Center Freiburg—Bad Krozingen, Medical Faculty, University of Freiburg, Freiburg, Germany
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Eike M Wülfers
- Institute of Experimental Cardiovascular Medicine, University Heart Center Freiburg—Bad Krozingen, Medical Faculty, University of Freiburg, Freiburg, Germany
| | - Lucilla Giammarino
- Translational Cardiology, Department of Cardiology, Inselspital, Bern University Hospital, University of Bern, Buehlplatz 5, CH-3012 Bern, Switzerland
- Department of Translational Cardiology/Electrophysiology, Institute of Physiology, University of Bern, Bern, Switzerland
| | - Iask Edler
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Jessica J Jowais
- Department of Physiology and Biophysics, University of Miami, Miami, FL, USA
| | - Marina Rieder
- Department of Cardiology and Angiology I, University Heart Center Freiburg, Medical Faculty, University of Freiburg, Freiburg, Germany
- Translational Cardiology, Department of Cardiology, Inselspital, Bern University Hospital, University of Bern, Buehlplatz 5, CH-3012 Bern, Switzerland
- Department of Translational Cardiology/Electrophysiology, Institute of Physiology, University of Bern, Bern, Switzerland
| | - Stefanie Perez-Feliz
- Department of Cardiology and Angiology I, University Heart Center Freiburg, Medical Faculty, University of Freiburg, Freiburg, Germany
- Institute of Experimental Cardiovascular Medicine, University Heart Center Freiburg—Bad Krozingen, Medical Faculty, University of Freiburg, Freiburg, Germany
| | - Gideon Koren
- Division of Cardiology, Cardiovascular Research Center, Brown University, Providence, RI, USA
| | - Zsuzsanna Bősze
- Animal Biotechnology Department, NARIC Agricultural Biotechnology Institute, Gödöllő, Hungary
| | - András Varró
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Manfred Zehender
- Department of Cardiology and Angiology I, University Heart Center Freiburg, Medical Faculty, University of Freiburg, Freiburg, Germany
| | - Michael Brunner
- Department of Cardiology and Angiology I, University Heart Center Freiburg, Medical Faculty, University of Freiburg, Freiburg, Germany
- Department of Cardiology and Medical Intensive Care, St. Josefskrankenhaus, Freiburg, Germany
| | - Christoph Bode
- Department of Cardiology and Angiology I, University Heart Center Freiburg, Medical Faculty, University of Freiburg, Freiburg, Germany
| | - Sara I Liin
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Hans Peter Larsson
- Department of Physiology and Biophysics, University of Miami, Miami, FL, USA
| | - István Baczkó
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Katja E Odening
- Department of Cardiology and Angiology I, University Heart Center Freiburg, Medical Faculty, University of Freiburg, Freiburg, Germany
- Translational Cardiology, Department of Cardiology, Inselspital, Bern University Hospital, University of Bern, Buehlplatz 5, CH-3012 Bern, Switzerland
- Department of Translational Cardiology/Electrophysiology, Institute of Physiology, University of Bern, Bern, Switzerland
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12
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Tajti G, Szanto TG, Csoti A, Racz G, Evaristo C, Hajdu P, Panyi G. Immunomagnetic separation is a suitable method for electrophysiology and ion channel pharmacology studies on T cells. Channels (Austin) 2021; 15:53-66. [PMID: 33356811 PMCID: PMC7781520 DOI: 10.1080/19336950.2020.1859753] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 12/01/2020] [Accepted: 12/01/2020] [Indexed: 12/11/2022] Open
Abstract
Ion channels play pivotal role in the physiological and pathological function of immune cells. As immune cells represent a functionally diverse population, subtype-specific functional studies, such as single-cell electrophysiology require proper subset identification and separation. Magnetic-activated cell sorting (MACS) techniques provide an alternative to fluorescence-activated cell sorting (FACS), however, the potential impact of MACS-related beads on the biophysical and pharmacological properties of the ion channels were not studied yet. We studied the aforementioned properties of the voltage-gated Kv1.3 K+ channel in activated CD4+ T-cells as well as the membrane capacitance using whole-cell patch-clamp following immunomagnetic positive separation, using the REAlease® kit. This kit allows three experimental configurations: bead-bound configuration, bead-free configuration following the removal of magnetic beads, and the label-free configuration following removal of CD4 recognizing antibody fragments. As controls, we used FACS separation as well as immunomagnetic negative selection. The membrane capacitance and of the biophysical parameters of Kv1.3 gating, voltage-dependence of steady-state activation and inactivation kinetics of the current were not affected by the presence of MACS-related compounds on the cell surface. We found subtle differences in the activation kinetics of the Kv1.3 current that could not be explained by the presence of MACS-related compounds. Neither the equilibrium block of Kv1.3 by TEA+ or charybdotoxin (ChTx) nor the kinetics of ChTx block are affected by the presence of the magnetics beads on the cell surface. Based on our results MACS is a suitable method to separate cells for studying ion channels in non-excitable cells, such as T-lymphocytes.
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Affiliation(s)
- Gabor Tajti
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Tibor Gabor Szanto
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Agota Csoti
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Greta Racz
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - César Evaristo
- R&D Reagents Chemical Biology, Miltenyi Biotec B.V. & Co. KG, Bergisch Gladbach, Germany
| | - Peter Hajdu
- Department of Biophysics and Cell Biology, Faculty of Dentistry, University of Debrecen, Debrecen, Hungary
| | - Gyorgy Panyi
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
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13
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Kovacs T, Sohajda T, Szente L, Nagy P, Panyi G, Varga Z, Zakany F. Cyclodextrins Exert a Ligand-like Current Inhibitory Effect on the K V1.3 Ion Channel Independent of Membrane Cholesterol Extraction. Front Mol Biosci 2021; 8:735357. [PMID: 34805269 PMCID: PMC8599428 DOI: 10.3389/fmolb.2021.735357] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 10/19/2021] [Indexed: 12/01/2022] Open
Abstract
Cyclodextrins (CDs) are cyclic oligosaccharides capable of forming water-soluble complexes with a variety of otherwise poorly soluble molecules including cholesterol and different drugs. Consistently, CDs are widely used in research and clinical practice to deplete cholesterol from cellular membranes or to increase solubility and bioavailability of different pharmaceuticals at local concentrations in the millimolar range. Effects of CDs exerted on cellular functions are generally thought to originate from reductions in cholesterol levels. Potential direct, ligand-like CD effects are largely neglected in spite of several recent studies reporting direct interaction between CDs and proteins including AMP-activated protein kinase, β-amyloid peptides, and α-synuclein. In this study, by using patch-clamp technique, time-resolved quantitation of cholesterol levels and biophysical parameters and applying cholesterol-extracting and non-cholesterol-extracting CDs at 1 and 5 mM concentrations, we provide evidence for a previously unexplored ligand-like, cholesterol-independent current inhibitory effect of CDs on KV1.3, a prototypical voltage-gated potassium channel with pathophysiological relevance in various autoimmune and neurodegenerative disorders. Our findings propose that potential direct CD effects on KV channels should be taken into consideration when interpreting functional consequences of CD treatments in both research and clinical practice. Furthermore, current-blocking effects of CDs on KV channels at therapeutically relevant concentrations might contribute to additional beneficial or adverse effects during their therapeutic applications.
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Affiliation(s)
- Tamas Kovacs
- Division of Biophysics, Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Tamas Sohajda
- CycloLab Cyclodextrin R and D Laboratory Ltd., Budapest, Hungary
| | - Lajos Szente
- CycloLab Cyclodextrin R and D Laboratory Ltd., Budapest, Hungary
| | - Peter Nagy
- Division of Biophysics, Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Gyorgy Panyi
- Division of Biophysics, Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Zoltan Varga
- Division of Biophysics, Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Florina Zakany
- Division of Biophysics, Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
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14
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Larsson JE, Karlsson U, Wu X, Liin SI. Combining endocannabinoids with retigabine for enhanced M-channel effect and improved KV7 subtype selectivity. J Gen Physiol 2021; 152:151732. [PMID: 32365171 PMCID: PMC7398146 DOI: 10.1085/jgp.202012576] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 03/25/2020] [Indexed: 12/22/2022] Open
Abstract
Retigabine is unique among anticonvulsant drugs by targeting the neuronal M-channel, which is composed of KV7.2/KV7.3 and contributes to the negative neuronal resting membrane potential. Unfortunately, retigabine causes adverse effects, which limits its clinical use. Adverse effects may be reduced by developing M-channel activators with improved KV7 subtype selectivity. The aim of this study was to evaluate the prospect of endocannabinoids as M-channel activators, either in isolation or combined with retigabine. Human KV7 channels were expressed in Xenopus laevis oocytes. The effect of extracellular application of compounds with different properties was studied using two-electrode voltage clamp electrophysiology. Site-directed mutagenesis was used to construct channels with mutated residues to aid in the mechanistic understanding of these effects. We find that arachidonoyl-L-serine (ARA-S), a weak endocannabinoid, potently activates the human M-channel expressed in Xenopus oocytes. Importantly, we show that ARA-S activates the M-channel via a different mechanism and displays a different KV7 subtype selectivity compared with retigabine. We demonstrate that coapplication of ARA-S and retigabine at low concentrations retains the effect on the M-channel while limiting effects on other KV7 subtypes. Our findings suggest that improved KV7 subtype selectivity of M-channel activators can be achieved through strategically combining compounds with different subtype selectivity.
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Affiliation(s)
- Johan E Larsson
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Urban Karlsson
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Xiongyu Wu
- Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden
| | - Sara I Liin
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
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15
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Bohannon BM, Wu X, Wu X, Perez ME, Liin SI, Larsson HP. Polyunsaturated fatty acids produce a range of activators for heterogeneous IKs channel dysfunction. J Gen Physiol 2021; 152:133474. [PMID: 31865382 PMCID: PMC7062506 DOI: 10.1085/jgp.201912396] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 09/05/2019] [Accepted: 11/27/2019] [Indexed: 01/28/2023] Open
Abstract
Repolarization and termination of the ventricular cardiac action potential is highly dependent on the activation of the slow delayed-rectifier potassium IKs channel. Disruption of the IKs current leads to the most common form of congenital long QT syndrome (LQTS), a disease that predisposes patients to ventricular arrhythmias and sudden cardiac death. We previously demonstrated that polyunsaturated fatty acid (PUFA) analogues increase outward K+ current in wild type and LQTS-causing mutant IKs channels. Our group has also demonstrated the necessity of a negatively charged PUFA head group for potent activation of the IKs channel through electrostatic interactions with the voltage-sensing and pore domains. Here, we test whether the efficacy of the PUFAs can be tuned by the presence of different functional groups in the PUFA head, thereby altering the electrostatic interactions of the PUFA head group with the voltage sensor or the pore. We show that PUFA analogues with taurine and cysteic head groups produced the most potent activation of IKs channels, largely by shifting the voltage dependence of activation. In comparison, the effect on voltage dependence of PUFA analogues with glycine and aspartate head groups was half that of the taurine and cysteic head groups, whereas the effect on maximal conductance was similar. Increasing the number of potentially negatively charged moieties did not enhance the effects of the PUFA on the IKs channel. Our results show that one can tune the efficacy of PUFAs on IKs channels by altering the pKa of the PUFA head group. Different PUFAs with different efficacy on IKs channels could be developed into more personalized treatments for LQTS patients with a varying degree of IKs channel dysfunction.
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Affiliation(s)
- Briana M Bohannon
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, FL
| | - Xiaoan Wu
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, FL
| | - Xiongyu Wu
- Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden
| | - Marta E Perez
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, FL
| | - Sara I Liin
- Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden
| | - H Peter Larsson
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, FL
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16
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Modulating the voltage sensor of a cardiac potassium channel shows antiarrhythmic effects. Proc Natl Acad Sci U S A 2021; 118:2024215118. [PMID: 33990467 DOI: 10.1073/pnas.2024215118] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Cardiac arrhythmias are the most common cause of sudden cardiac death worldwide. Lengthening the ventricular action potential duration (APD), either congenitally or via pathologic or pharmacologic means, predisposes to a life-threatening ventricular arrhythmia, Torsade de Pointes. IKs (KCNQ1+KCNE1), a slowly activating K+ current, plays a role in action potential repolarization. In this study, we screened a chemical library in silico by docking compounds to the voltage-sensing domain (VSD) of the IKs channel. Here, we show that C28 specifically shifted IKs VSD activation in ventricle to more negative voltages and reversed the drug-induced lengthening of APD. At the same dosage, C28 did not cause significant changes of the normal APD in either ventricle or atrium. This study provides evidence in support of a computational prediction of IKs VSD activation as a potential therapeutic approach for all forms of APD prolongation. This outcome could expand the therapeutic efficacy of a myriad of currently approved drugs that may trigger arrhythmias.
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17
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Yazdi S, Nikesjö J, Miranda W, Corradi V, Tieleman DP, Noskov SY, Larsson HP, Liin SI. Identification of PUFA interaction sites on the cardiac potassium channel KCNQ1. J Gen Physiol 2021; 153:212043. [PMID: 33939797 PMCID: PMC8097404 DOI: 10.1085/jgp.202012850] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 03/19/2021] [Accepted: 04/17/2021] [Indexed: 12/16/2022] Open
Abstract
Polyunsaturated fatty acids (PUFAs), but not saturated fatty acids, modulate ion channels such as the cardiac KCNQ1 channel, although the mechanism is not completely understood. Using both simulations and experiments, we find that PUFAs interact directly with the KCNQ1 channel via two different binding sites: one at the voltage sensor and one at the pore. These two amphiphilic binding pockets stabilize the negatively charged PUFA head group by electrostatic interactions with R218, R221, and K316, while the hydrophobic PUFA tail is selectively stabilized by cassettes of hydrophobic residues. The rigid saturated tail of stearic acid prevents close contacts with KCNQ1. By contrast, the mobile tail of PUFA linoleic acid can be accommodated in the crevice of the hydrophobic cassette, a defining feature of PUFA selectivity in KCNQ1. In addition, we identify Y268 as a critical PUFA anchor point underlying fatty acid selectivity. Combined, this study provides molecular models of direct interactions between PUFAs and KCNQ1 and identifies selectivity mechanisms. Long term, this understanding may open new avenues for drug development based on PUFA mechanisms.
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Affiliation(s)
- Samira Yazdi
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Johan Nikesjö
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Williams Miranda
- Centre for Molecular Simulations, Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Valentina Corradi
- Centre for Molecular Simulations, Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - D Peter Tieleman
- Centre for Molecular Simulations, Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Sergei Yu Noskov
- Centre for Molecular Simulations, Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - H Peter Larsson
- Department of Physiology and Biophysics, University of Miami, Miami, FL
| | - Sara I Liin
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
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18
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Targeting of Potassium Channels in Cardiac Arrhythmias. Trends Pharmacol Sci 2021; 42:491-506. [PMID: 33858691 DOI: 10.1016/j.tips.2021.03.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 03/14/2021] [Accepted: 03/17/2021] [Indexed: 02/07/2023]
Abstract
Cardiomyocytes are endowed with a complex repertoire of ion channels, responsible for the generation of action potentials (APs), travelling waves of electrical excitation, propagating throughout the heart and leading to cardiac contractions. Cardiac AP waveforms are shaped by a striking diversity of K+ channels. The pivotal role of K+ channels in cardiac health and disease is underscored by the dramatic impact that K+ channel dysfunction has on cardiac arrhythmias. The development of drugs targeted to specific K+ channels is expected to provide an optimized approach to antiarrhythmic therapy. Here, we review the functional roles of cardiac potassium channels under normal and diseased states. We survey current antiarrhythmic drugs (AADs) targeted to voltage-gated and Ca2+-activated K+ channels and highlight future research opportunities.
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19
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Silverå Ejneby M, Gromova A, Ottosson NE, Borg S, Estrada-Mondragón A, Yazdi S, Apostolakis P, Elinder F, Delemotte L. Resin-acid derivatives bind to multiple sites on the voltage-sensor domain of the Shaker potassium channel. J Gen Physiol 2021; 153:211862. [PMID: 33683319 PMCID: PMC7944402 DOI: 10.1085/jgp.202012676] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 11/30/2020] [Accepted: 01/27/2021] [Indexed: 01/10/2023] Open
Abstract
Voltage-gated potassium (KV) channels can be opened by negatively charged resin acids and their derivatives. These resin acids have been proposed to attract the positively charged voltage-sensor helix (S4) toward the extracellular side of the membrane by binding to a pocket located between the lipid-facing extracellular ends of the transmembrane segments S3 and S4. By contrast to this proposed mechanism, neutralization of the top gating charge of the Shaker KV channel increased resin-acid-induced opening, suggesting other mechanisms and sites of action. Here, we explore the binding of two resin-acid derivatives, Wu50 and Wu161, to the activated/open state of the Shaker KV channel by a combination of in silico docking, molecular dynamics simulations, and electrophysiology of mutated channels. We identified three potential resin-acid-binding sites around S4: (1) the S3/S4 site previously suggested, in which positively charged residues introduced at the top of S4 are critical to keep the compound bound, (2) a site in the cleft between S4 and the pore domain (S4/pore site), in which a tryptophan at the top of S6 and the top gating charge of S4 keeps the compound bound, and (3) a site located on the extracellular side of the voltage-sensor domain, in a cleft formed by S1-S4 (the top-VSD site). The multiple binding sites around S4 and the anticipated helical-screw motion of the helix during activation make the effect of resin-acid derivatives on channel function intricate. The propensity of a specific resin acid to activate and open a voltage-gated channel likely depends on its exact binding dynamics and the types of interactions it can form with the protein in a state-specific manner.
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Affiliation(s)
- Malin Silverå Ejneby
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Arina Gromova
- Science for Life Laboratory, Department of Applied Physics, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Nina E Ottosson
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Stina Borg
- Science for Life Laboratory, Department of Applied Physics, KTH Royal Institute of Technology, Stockholm, Sweden
| | | | - Samira Yazdi
- Science for Life Laboratory, Department of Applied Physics, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Panagiotis Apostolakis
- Science for Life Laboratory, Department of Applied Physics, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Fredrik Elinder
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Lucie Delemotte
- Science for Life Laboratory, Department of Applied Physics, KTH Royal Institute of Technology, Stockholm, Sweden
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20
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Miranda WE, Guo J, Mesa-Galloso H, Corradi V, Lees-Miller JP, Tieleman DP, Duff HJ, Noskov SY. Lipid regulation of hERG1 channel function. Nat Commun 2021; 12:1409. [PMID: 33658490 PMCID: PMC7930123 DOI: 10.1038/s41467-021-21681-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 01/29/2021] [Indexed: 01/31/2023] Open
Abstract
The lipid regulation of mammalian ion channel function has emerged as a fundamental mechanism in the control of electrical signalling and transport specificity in various cell types. In this work, we combine molecular dynamics simulations, mutagenesis, and electrophysiology to provide mechanistic insights into how lipophilic molecules (ceramide-sphingolipid probe) alter gating kinetics and K+ currents of hERG1. We show that the sphingolipid probe induced a significant left shift of activation voltage, faster deactivation rates, and current blockade comparable to traditional hERG1 blockers. Microseconds-long MD simulations followed by experimental mutagenesis elucidated ceramide specific binding locations at the interface between the pore and voltage sensing domains. This region constitutes a unique crevice present in mammalian channels with a non-swapped topology. The combined experimental and simulation data provide evidence for ceramide-induced allosteric modulation of the channel by a conformational selection mechanism.
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Affiliation(s)
- Williams E Miranda
- Centre for Molecular Simulation and Department of Biological Sciences, 507 Campus Drive, University of Calgary, Calgary, AB, Canada
| | - Jiqing Guo
- Department of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, 3280 Hospital Dr., University of Calgary, Calgary, AB, Canada
| | - Haydee Mesa-Galloso
- Centre for Molecular Simulation and Department of Biological Sciences, 507 Campus Drive, University of Calgary, Calgary, AB, Canada
| | - Valentina Corradi
- Centre for Molecular Simulation and Department of Biological Sciences, 507 Campus Drive, University of Calgary, Calgary, AB, Canada
| | - James P Lees-Miller
- Department of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, 3280 Hospital Dr., University of Calgary, Calgary, AB, Canada
| | - D Peter Tieleman
- Centre for Molecular Simulation and Department of Biological Sciences, 507 Campus Drive, University of Calgary, Calgary, AB, Canada.
| | - Henry J Duff
- Department of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, 3280 Hospital Dr., University of Calgary, Calgary, AB, Canada.
| | - Sergei Yu Noskov
- Centre for Molecular Simulation and Department of Biological Sciences, 507 Campus Drive, University of Calgary, Calgary, AB, Canada.
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21
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Wu X, Larsson HP. Insights into Cardiac IKs (KCNQ1/KCNE1) Channels Regulation. Int J Mol Sci 2020; 21:ijms21249440. [PMID: 33322401 PMCID: PMC7763278 DOI: 10.3390/ijms21249440] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 12/05/2020] [Accepted: 12/09/2020] [Indexed: 12/19/2022] Open
Abstract
The delayed rectifier potassium IKs channel is an important regulator of the duration of the ventricular action potential. Hundreds of mutations in the genes (KCNQ1 and KCNE1) encoding the IKs channel cause long QT syndrome (LQTS). LQTS is a heart disorder that can lead to severe cardiac arrhythmias and sudden cardiac death. A better understanding of the IKs channel (here called the KCNQ1/KCNE1 channel) properties and activities is of great importance to find the causes of LQTS and thus potentially treat LQTS. The KCNQ1/KCNE1 channel belongs to the superfamily of voltage-gated potassium channels. The KCNQ1/KCNE1 channel consists of both the pore-forming subunit KCNQ1 and the modulatory subunit KCNE1. KCNE1 regulates the function of the KCNQ1 channel in several ways. This review aims to describe the current structural and functional knowledge about the cardiac KCNQ1/KCNE1 channel. In addition, we focus on the modulation of the KCNQ1/KCNE1 channel and its potential as a target therapeutic of LQTS.
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22
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Kang PW, Westerlund AM, Shi J, White KM, Dou AK, Cui AH, Silva JR, Delemotte L, Cui J. Calmodulin acts as a state-dependent switch to control a cardiac potassium channel opening. SCIENCE ADVANCES 2020; 6:6/50/eabd6798. [PMID: 33310856 PMCID: PMC7732179 DOI: 10.1126/sciadv.abd6798] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 10/27/2020] [Indexed: 05/09/2023]
Abstract
Calmodulin (CaM) and phosphatidylinositol 4,5-bisphosphate (PIP2) are potent regulators of the voltage-gated potassium channel KCNQ1 (KV7.1), which conducts the cardiac I Ks current. Although cryo-electron microscopy structures revealed intricate interactions between the KCNQ1 voltage-sensing domain (VSD), CaM, and PIP2, the functional consequences of these interactions remain unknown. Here, we show that CaM-VSD interactions act as a state-dependent switch to control KCNQ1 pore opening. Combined electrophysiology and molecular dynamics network analysis suggest that VSD transition into the fully activated state allows PIP2 to compete with CaM for binding to VSD. This leads to conformational changes that alter VSD-pore coupling to stabilize open states. We identify a motif in the KCNQ1 cytosolic domain, which works downstream of CaM-VSD interactions to facilitate the conformational change. Our findings suggest a gating mechanism that integrates PIP2 and CaM in KCNQ1 voltage-dependent activation, yielding insights into how KCNQ1 gains the phenotypes critical for its physiological function.
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Affiliation(s)
- Po Wei Kang
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity, and Arrhythmia Center, Washington University, St. Louis, MO 63130, USA
| | - Annie M Westerlund
- Department of Applied Physics, KTH Royal Institute of Technology, Science for Life Laboratory, Stockholm, Sweden
| | - Jingyi Shi
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity, and Arrhythmia Center, Washington University, St. Louis, MO 63130, USA
| | - Kelli McFarland White
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity, and Arrhythmia Center, Washington University, St. Louis, MO 63130, USA
| | - Alex K Dou
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity, and Arrhythmia Center, Washington University, St. Louis, MO 63130, USA
| | - Amy H Cui
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity, and Arrhythmia Center, Washington University, St. Louis, MO 63130, USA
| | - Jonathan R Silva
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity, and Arrhythmia Center, Washington University, St. Louis, MO 63130, USA
| | - Lucie Delemotte
- Department of Applied Physics, KTH Royal Institute of Technology, Science for Life Laboratory, Stockholm, Sweden.
| | - Jianmin Cui
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity, and Arrhythmia Center, Washington University, St. Louis, MO 63130, USA.
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23
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Skarsfeldt MA, Liin SI, Larsson HP, Bentzen BH. Polyunsaturated fatty acid-derived I Ks channel activators shorten the QT interval ex-vivo and in-vivo. Acta Physiol (Oxf) 2020; 229:e13471. [PMID: 32223014 PMCID: PMC8633721 DOI: 10.1111/apha.13471] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 03/17/2020] [Accepted: 03/18/2020] [Indexed: 12/16/2022]
Abstract
AIM We aimed to assess the ability of natural and modified polyunsaturated fatty acids (PUFAs) to shorten QT interval in ex-vivo and in-vivo guinea pig hearts. METHODS The effect of one natural (docosahexaenoic acid [DHA]) and three modified (linoleoyl glycine [Lin-GLY], docosahexaenoyl glycine [DHA-GLY], N-arachidonoyl taurine [N-AT]) PUFAs on ventricular action potential duration (APD) and QT interval was studied in a E4031 drug-induced long QT2 model of ex-vivo guinea pig hearts. The effect of DHA-GLY on QT interval was also studied in in-vivo guinea pig hearts upon intravenous administration. The effect of modified PUFAs on IKs was studied using Xenopus laevis oocytes expressing human KCNQ1 and KCNE1. RESULTS All tested PUFAs shortened ADP and QT interval in ex-vivo guinea pig hearts, however, with different ability in restoring baseline APD/QT interval with specific modified PUFAs being most efficacious. Despite comparable ability in activating the human KCNQ1/KCNE1 channel, Lin-GLY was not as effective in shortening APD/QT interval as DHA-GLY in ex-vivo hearts. By constructing a guinea pig-like KCNE1, we found Lin-GLY to induce less activating effect compared with DHA-GLY on human KCNQ1 co-expressed with guinea pig-like KCNE1. Docosahexaenoyl glycine was studied in more detail and was found to shorten QT interval in in-vivo guinea pig hearts. CONCLUSION Our results show that specific PUFAs shorten QT interval in guinea pig hearts. The tendency of modified PUFAs with pronounced IKs channel activating effect to better restore QT interval suggests that modifying PUFAs to target the IKs channel is a means to improve the QT-shortening effect.
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Affiliation(s)
- Mark A Skarsfeldt
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
- Department of Physiology and Biophysics, University of Miami, Miami, FL, USA
| | - Sara I Liin
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Hans P Larsson
- Department of Physiology and Biophysics, University of Miami, Miami, FL, USA
| | - Bo H Bentzen
- The Danish Arrhythmia Research Centre and Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
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24
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Odening KE. Mechanism-based QT/APD-shortening therapy for potassium-channel-based long-QT syndromes? Acta Physiol (Oxf) 2020; 229:e13481. [PMID: 32330372 DOI: 10.1111/apha.13481] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Katja E Odening
- Translational Cardiology, Department of Cardiology, Inselspital, Bern University Hospital, and Institute of Physiology, University of Bern, Bern, Switzerland.,Department of Cardiology and Angiology I, Medical Faculty, Heart Center University of Freiburg, Freiburg, Germany
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25
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Liu Y, Xu X, Gao J, Naffaa MM, Liang H, Shi J, Wang HZ, Yang ND, Hou P, Zhao W, White KM, Kong W, Dou A, Cui A, Zhang G, Cohen IS, Zou X, Cui J. A PIP 2 substitute mediates voltage sensor-pore coupling in KCNQ activation. Commun Biol 2020; 3:385. [PMID: 32678288 PMCID: PMC7367283 DOI: 10.1038/s42003-020-1104-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Accepted: 06/22/2020] [Indexed: 12/25/2022] Open
Abstract
KCNQ family K+ channels (KCNQ1-5) in the heart, nerve, epithelium and ear require phosphatidylinositol 4,5-bisphosphate (PIP2) for voltage dependent activation. While membrane lipids are known to regulate voltage sensor domain (VSD) activation and pore opening in voltage dependent gating, PIP2 was found to interact with KCNQ1 and mediate VSD-pore coupling. Here, we show that a compound CP1, identified in silico based on the structures of both KCNQ1 and PIP2, can substitute for PIP2 to mediate VSD-pore coupling. Both PIP2 and CP1 interact with residues amongst a cluster of amino acids critical for VSD-pore coupling. CP1 alters KCNQ channel function due to different interactions with KCNQ compared with PIP2. We also found that CP1 returned drug-induced action potential prolongation in ventricular myocytes to normal durations. These results reveal the structural basis of PIP2 regulation of KCNQ channels and indicate a potential approach for the development of anti-arrhythmic therapy.
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Affiliation(s)
- Yongfeng Liu
- grid.4367.60000 0001 2355 7002Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University in Saint Louis, Saint Louis, MO 63130 USA
| | - Xianjin Xu
- grid.134936.a0000 0001 2162 3504Dalton Cardiovascular Research Center, Department of Physics and Astronomy, Department of Biochemistry, Institute for Data Science & Informatics, University of Missouri, Columbia, MO 65211 USA
| | - Junyuan Gao
- grid.36425.360000 0001 2216 9681Department of Physiology and Biophysics, and Institute for Molecular Cardiology, Stony Brook University, Stony Brook, NY 11794 USA
| | - Moawiah M. Naffaa
- grid.4367.60000 0001 2355 7002Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University in Saint Louis, Saint Louis, MO 63130 USA
| | - Hongwu Liang
- grid.4367.60000 0001 2355 7002Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University in Saint Louis, Saint Louis, MO 63130 USA
| | - Jingyi Shi
- grid.4367.60000 0001 2355 7002Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University in Saint Louis, Saint Louis, MO 63130 USA
| | - Hong Zhan Wang
- grid.36425.360000 0001 2216 9681Department of Physiology and Biophysics, and Institute for Molecular Cardiology, Stony Brook University, Stony Brook, NY 11794 USA
| | - Nien-Du Yang
- grid.4367.60000 0001 2355 7002Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University in Saint Louis, Saint Louis, MO 63130 USA
| | - Panpan Hou
- grid.4367.60000 0001 2355 7002Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University in Saint Louis, Saint Louis, MO 63130 USA
| | - Wenshan Zhao
- grid.4367.60000 0001 2355 7002Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University in Saint Louis, Saint Louis, MO 63130 USA
| | - Kelli McFarland White
- grid.4367.60000 0001 2355 7002Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University in Saint Louis, Saint Louis, MO 63130 USA
| | - Wenjuan Kong
- grid.4367.60000 0001 2355 7002Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University in Saint Louis, Saint Louis, MO 63130 USA
| | - Alex Dou
- grid.4367.60000 0001 2355 7002Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University in Saint Louis, Saint Louis, MO 63130 USA
| | - Amy Cui
- grid.4367.60000 0001 2355 7002Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University in Saint Louis, Saint Louis, MO 63130 USA
| | - Guohui Zhang
- grid.4367.60000 0001 2355 7002Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University in Saint Louis, Saint Louis, MO 63130 USA
| | - Ira S. Cohen
- grid.36425.360000 0001 2216 9681Department of Physiology and Biophysics, and Institute for Molecular Cardiology, Stony Brook University, Stony Brook, NY 11794 USA
| | - Xiaoqin Zou
- grid.134936.a0000 0001 2162 3504Dalton Cardiovascular Research Center, Department of Physics and Astronomy, Department of Biochemistry, Institute for Data Science & Informatics, University of Missouri, Columbia, MO 65211 USA
| | - Jianmin Cui
- grid.4367.60000 0001 2355 7002Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University in Saint Louis, Saint Louis, MO 63130 USA
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26
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Larsson JE, Frampton DJA, Liin SI. Polyunsaturated Fatty Acids as Modulators of K V7 Channels. Front Physiol 2020; 11:641. [PMID: 32595524 PMCID: PMC7300222 DOI: 10.3389/fphys.2020.00641] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Accepted: 05/20/2020] [Indexed: 11/25/2022] Open
Abstract
Voltage-gated potassium channels of the KV7 family are expressed in many tissues. The physiological importance of KV7 channels is evident from specific forms of disorders linked to dysfunctional KV7 channels, including variants of epilepsy, cardiac arrhythmia and hearing impairment. Thus, understanding how KV7 channels are regulated in the body is of great interest. This Mini Review focuses on the effects of polyunsaturated fatty acids (PUFAs) on KV7 channel activity and possible underlying mechanisms of action. By summarizing reported effects of PUFAs on KV7 channels and native KV7-mediated currents, we conclude that the generally observed effect is a PUFA-induced increase in current amplitude. The increase in current is commonly associated with a shift in the voltage-dependence of channel opening and in some cases with increased maximum conductance. Auxiliary KCNE subunits, which associate with KV7 channels in certain tissues, may influence PUFA effects, though findings are conflicting. Both direct and indirect activating PUFA effects have been described, direct effects having been most extensively studied on KV7.1. The negative charge of the PUFA head-group has been identified as critical for electrostatic interaction with conserved positively charged amino acids in transmembrane segments 4 and 6. Additionally, the localization of double bonds in the PUFA tail tunes the apparent affinity of PUFAs to KV7.1. Indirect effects include those mediated by PUFA metabolites. Indirect inhibitory effects involve KV7 channel degradation and re-distribution from lipid rafts. Understanding how PUFAs regulate KV7 channels may provide insight into physiological regulation of KV7 channels and bring forth new therapeutic strategies.
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Affiliation(s)
- Johan E Larsson
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Damon J A Frampton
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Sara I Liin
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
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27
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Wang Y, Eldstrom J, Fedida D. Gating and Regulation of KCNQ1 and KCNQ1 + KCNE1 Channel Complexes. Front Physiol 2020; 11:504. [PMID: 32581825 PMCID: PMC7287213 DOI: 10.3389/fphys.2020.00504] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 04/24/2020] [Indexed: 12/20/2022] Open
Abstract
The IKs channel complex is formed by the co-assembly of Kv7.1 (KCNQ1), a voltage-gated potassium channel, with its β-subunit, KCNE1 and the association of numerous accessory regulatory molecules such as PIP2, calmodulin, and yotiao. As a result, the IKs potassium current shows kinetic and regulatory flexibility, which not only allows IKs to fulfill physiological roles as disparate as cardiac repolarization and the maintenance of endolymph K+ homeostasis, but also to cause significant disease when it malfunctions. Here, we review new areas of understanding in the assembly, kinetics of activation and inactivation, voltage-sensor pore coupling, unitary events and regulation of this important ion channel complex, all of which have been given further impetus by the recent solution of cryo-EM structural representations of KCNQ1 alone and KCNQ1+KCNE3. Recently, the stoichiometric ratio of KCNE1 to KCNQ1 subunits has been confirmed to be variable up to a ratio of 4:4, rather than fixed at 2:4, and we will review the results and new methodologies that support this conclusion. Significant advances have been made in understanding differences between KCNQ1 and IKs gating using voltage clamp fluorimetry and mutational analysis to illuminate voltage sensor activation and inactivation, and the relationship between voltage sensor translation and pore domain opening. We now understand that the KCNQ1 pore can open with different permeabilities and conductance when the voltage sensor is in partially or fully activated positions, and the ability to make robust single channel recordings from IKs channels has also revealed the complicated pore subconductance architecture during these opening steps, during inactivation, and regulation by 1−4 associated KCNE1 subunits. Experiments placing mutations into individual voltage sensors to drastically change voltage dependence or prevent their movement altogether have demonstrated that the activation of KCNQ1 alone and IKs can best be explained using allosteric models of channel gating. Finally, we discuss how the intrinsic gating properties of KCNQ1 and IKs are highly modulated through the impact of intracellular signaling molecules and co-factors such as PIP2, protein kinase A, calmodulin and ATP, all of which modulate IKs current kinetics and contribute to diverse IKs channel complex function.
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Affiliation(s)
- Yundi Wang
- Department of Anesthesiology, Pharmacology & Therapeutics, The University of British Columbia, Vancouver, BC, Canada
| | - Jodene Eldstrom
- Department of Anesthesiology, Pharmacology & Therapeutics, The University of British Columbia, Vancouver, BC, Canada
| | - David Fedida
- Department of Anesthesiology, Pharmacology & Therapeutics, The University of British Columbia, Vancouver, BC, Canada
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28
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Brewer KR, Kuenze G, Vanoye CG, George AL, Meiler J, Sanders CR. Structures Illuminate Cardiac Ion Channel Functions in Health and in Long QT Syndrome. Front Pharmacol 2020; 11:550. [PMID: 32431610 PMCID: PMC7212895 DOI: 10.3389/fphar.2020.00550] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 04/09/2020] [Indexed: 12/13/2022] Open
Abstract
The cardiac action potential is critical to the production of a synchronized heartbeat. This electrical impulse is governed by the intricate activity of cardiac ion channels, among them the cardiac voltage-gated potassium (Kv) channels KCNQ1 and hERG as well as the voltage-gated sodium (Nav) channel encoded by SCN5A. Each channel performs a highly distinct function, despite sharing a common topology and structural components. These three channels are also the primary proteins mutated in congenital long QT syndrome (LQTS), a genetic condition that predisposes to cardiac arrhythmia and sudden cardiac death due to impaired repolarization of the action potential and has a particular proclivity for reentrant ventricular arrhythmias. Recent cryo-electron microscopy structures of human KCNQ1 and hERG, along with the rat homolog of SCN5A and other mammalian sodium channels, provide atomic-level insight into the structure and function of these proteins that advance our understanding of their distinct functions in the cardiac action potential, as well as the molecular basis of LQTS. In this review, the gating, regulation, LQTS mechanisms, and pharmacological properties of KCNQ1, hERG, and SCN5A are discussed in light of these recent structural findings.
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Affiliation(s)
- Kathryn R. Brewer
- Center for Structural Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Department of Biochemistry, Vanderbilt University, Nashville, TN, United States
| | - Georg Kuenze
- Center for Structural Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States
| | - Carlos G. Vanoye
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Alfred L. George
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Jens Meiler
- Center for Structural Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States
- Department of Pharmacology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Institute for Drug Discovery, Leipzig University Medical School, Leipzig, Germany
| | - Charles R. Sanders
- Center for Structural Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Department of Biochemistry, Vanderbilt University, Nashville, TN, United States
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Bohannon BM, de la Cruz A, Wu X, Jowais JJ, Perez ME, Dykxhoorn DM, Liin SI, Larsson HP. Polyunsaturated fatty acid analogues differentially affect cardiac Na V, Ca V, and K V channels through unique mechanisms. eLife 2020; 9:51453. [PMID: 32207683 PMCID: PMC7159882 DOI: 10.7554/elife.51453] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 03/24/2020] [Indexed: 12/15/2022] Open
Abstract
The cardiac ventricular action potential depends on several voltage-gated ion channels, including NaV, CaV, and KV channels. Mutations in these channels can cause Long QT Syndrome (LQTS) which increases the risk for ventricular fibrillation and sudden cardiac death. Polyunsaturated fatty acids (PUFAs) have emerged as potential therapeutics for LQTS because they are modulators of voltage-gated ion channels. Here we demonstrate that PUFA analogues vary in their selectivity for human voltage-gated ion channels involved in the ventricular action potential. The effects of specific PUFA analogues range from selective for a specific ion channel to broadly modulating cardiac ion channels from all three families (NaV, CaV, and KV). In addition, a PUFA analogue selective for the cardiac IKs channel (Kv7.1/KCNE1) is effective in shortening the cardiac action potential in human-induced pluripotent stem cell-derived cardiomyocytes. Our data suggest that PUFA analogues could potentially be developed as therapeutics for LQTS and cardiac arrhythmia.
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Affiliation(s)
- Briana M Bohannon
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, United States
| | - Alicia de la Cruz
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, United States
| | - Xiaoan Wu
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, United States
| | - Jessica J Jowais
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, United States
| | - Marta E Perez
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, United States
| | - Derek M Dykxhoorn
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, United States
| | - Sara I Liin
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - H Peter Larsson
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, United States
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Short B. A range of activators for cardiac IKs channels. J Gen Physiol 2020; 152:e201912557. [PMID: 31922528 PMCID: PMC7062509 DOI: 10.1085/jgp.201912557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
JGP study suggests that varying the head group of polyunsaturated fatty acids could enable personalized treatments for long QT syndrome.
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31
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The membrane protein KCNQ1 potassium ion channel: Functional diversity and current structural insights. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1862:183148. [PMID: 31825788 DOI: 10.1016/j.bbamem.2019.183148] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 11/15/2019] [Accepted: 12/04/2019] [Indexed: 12/19/2022]
Abstract
BACKGROUND Ion channels play crucial roles in cellular biology, physiology, and communication including sensory perception. Voltage-gated potassium (Kv) channels execute their function by sensor activation, pore-coupling, and pore opening leading to K+ conductance. SCOPE OF REVIEW This review focuses on a voltage-gated K+ ion channel KCNQ1 (Kv 7.1). Firstly, discussing its positioning in the human ion chanome, and the role of KCNQ1 in the multitude of cellular processes. Next, we discuss the overall channel architecture and current structural insights on KCNQ1. Finally, the gating mechanism involving members of the KCNE family and its interaction with non-KCNE partners. MAJOR CONCLUSIONS KCNQ1 executes its important physiological functions via interacting with KCNE1 and non-KCNE1 proteins/molecules: calmodulin, PIP2, PKA. Although, KCNQ1 has been studied in great detail, several aspects of the channel structure and function still remain unexplored. This review emphasizes the structural and biophysical studies of KCNQ1, its interaction with KCNE1 and non-KCNE1 proteins and focuses on several seminal findings showing the role of VSD and the pore domain in the channel activation and gating properties. GENERAL SIGNIFICANCE KCNQ1 mutations can result in channel defects and lead to several diseases including atrial fibrillation and long QT syndrome. Therefore, a thorough structure-function understanding of this channel complex is essential to understand its role in both normal and disease biology. Moreover, unraveling the molecular mechanisms underlying the regulation of this channel complex will help to find therapeutic strategies for several diseases.
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