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Renigunta V, Xhaferri N, Shaikh IG, Schlegel J, Bisen R, Sanvido I, Kalpachidou T, Kummer K, Oliver D, Leitner MG, Lindner M. A versatile functional interaction between electrically silent K V subunits and K V7 potassium channels. Cell Mol Life Sci 2024; 81:301. [PMID: 39003683 DOI: 10.1007/s00018-024-05312-1] [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: 03/12/2024] [Revised: 05/23/2024] [Accepted: 06/10/2024] [Indexed: 07/15/2024]
Abstract
Voltage-gated K+ (KV) channels govern K+ ion flux across cell membranes in response to changes in membrane potential. They are formed by the assembly of four subunits, typically from the same family. Electrically silent KV channels (KVS), however, are unable to conduct currents on their own. It has been assumed that these KVS must obligatorily assemble with subunits from the KV2 family into heterotetrameric channels, thereby giving rise to currents distinct from those of homomeric KV2 channels. Herein, we show that KVS subunits indeed also modulate the activity, biophysical properties and surface expression of recombinant KV7 isoforms in a subunit-specific manner. Employing co-immunoprecipitation, and proximity labelling, we unveil the spatial coexistence of KVS and KV7 within a single protein complex. Electrophysiological experiments further indicate functional interaction and probably heterotetramer formation. Finally, single-cell transcriptomic analyses identify native cell types in which this KVS and KV7 interaction may occur. Our findings demonstrate that KV cross-family interaction is much more versatile than previously thought-possibly serving nature to shape potassium conductance to the needs of individual cell types.
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Affiliation(s)
- Vijay Renigunta
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps-University Marburg, 35037, Marburg, Germany
| | - Nermina Xhaferri
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps-University Marburg, 35037, Marburg, Germany
| | - Imran Gousebasha Shaikh
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps-University Marburg, 35037, Marburg, Germany
| | - Jonathan Schlegel
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps-University Marburg, 35037, Marburg, Germany
| | - Rajeshwari Bisen
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps-University Marburg, 35037, Marburg, Germany
| | - Ilaria Sanvido
- Institute of Physiology, Medical University of Innsbruck, Innsbruck, Austria
| | | | - Kai Kummer
- Institute of Physiology, Medical University of Innsbruck, Innsbruck, Austria
| | - Dominik Oliver
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps-University Marburg, 35037, Marburg, Germany
| | - Michael G Leitner
- Institute of Physiology, Medical University of Innsbruck, Innsbruck, Austria.
| | - Moritz Lindner
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps-University Marburg, 35037, Marburg, Germany.
- The Nuffield Laboratory of Ophthalmology, Sleep and Circadian Neuroscience Institute, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK.
- Department of Ophthalmology, Philipps University Marburg, 35037, Marburg, Germany.
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Li B, Karlova M, Zhang H, Pustovit OB, Mai L, Novoseletsky V, Podolyak D, Zaklyazminskaya EV, Abramochkin DV, Sokolova OS. A mutation in the cardiac KV7.1 channel possibly disrupts interaction with Yotiao protein. Biochem Biophys Res Commun 2024; 714:149947. [PMID: 38657442 DOI: 10.1016/j.bbrc.2024.149947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2024] [Revised: 04/08/2024] [Accepted: 04/15/2024] [Indexed: 04/26/2024]
Abstract
Here, we characterized the p.Arg583His (R583H) Kv7.1 mutation, identified in two unrelated families suffered from LQT syndrome. This mutation is located in the HС-HD linker of the cytoplasmic portion of the Kv7.1 channel. This linker, together with HD helix are responsible for binding the A-kinase anchoring protein 9 (AKAP9), Yotiao. We studied the electrophysiological characteristics of the mutated channel expressed in CHO-K1 along with KCNE1 subunit and Yotiao protein, using the whole-cell patch-clamp technique. We found that R583H mutation, even at the heterozygous state, impedes IKs activation. Molecular modeling showed that HС and HD helixes of the C-terminal part of Kv7.1 channel are swapped along the C-terminus length of the channel and that R583 position is exposed to the outer surface of HC-HD tandem coiled-coil. Interestingly, the adenylate cyclase activator, forskolin had a smaller effect on the mutant channel comparing with the WT protein, suggesting that R583H mutation may disrupt the interaction of the channel with the adaptor protein Yotiao and, therefore, may impair phosphorylation of the KCNQ1 channel.
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Affiliation(s)
- Bowen Li
- Department of Biology, MSU-BIT University, Shenzhen, Guangdong Province, China
| | - Maria Karlova
- Department of Biology, Moscow Lomonosov University, Moscow, Russia
| | - Han Zhang
- Department of Biology, MSU-BIT University, Shenzhen, Guangdong Province, China
| | | | - Lisha Mai
- Department of Biology, MSU-BIT University, Shenzhen, Guangdong Province, China
| | - Valery Novoseletsky
- Department of Biology, MSU-BIT University, Shenzhen, Guangdong Province, China
| | - Dmitry Podolyak
- Petrovsky Russian Scientific Center for Surgery, Moscow, Russia
| | | | | | - Olga S Sokolova
- Department of Biology, MSU-BIT University, Shenzhen, Guangdong Province, China; Department of Biology, Moscow Lomonosov University, Moscow, Russia.
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3
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Stott JB, Greenwood IA. G protein βγ regulation of KCNQ-encoded voltage-dependent K channels. Front Physiol 2024; 15:1382904. [PMID: 38655029 PMCID: PMC11035767 DOI: 10.3389/fphys.2024.1382904] [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: 02/06/2024] [Accepted: 03/25/2024] [Indexed: 04/26/2024] Open
Abstract
The KCNQ family is comprised of five genes and the expression products form voltage-gated potassium channels (Kv7.1-7.5) that have a major impact upon cellular physiology in many cell types. Each functional Kv7 channel forms as a tetramer that often associates with proteins encoded by the KCNE gene family (KCNE1-5) and is critically reliant upon binding of phosphatidylinositol bisphosphate (PIP2) and calmodulin. Other modulators like A-kinase anchoring proteins, ubiquitin ligases and Ca-calmodulin kinase II alter Kv7 channel function and trafficking in an isoform specific manner. It has now been identified that for Kv7.4, G protein βγ subunits (Gβγ) can be added to the list of key regulators and is paramount for channel activity. This article provides an overview of this nascent field of research, highlighting themes and directions for future study.
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Affiliation(s)
| | - Iain A. Greenwood
- Vascular Biology Research Group, Institute of Molecular and Clinical Sciences, St George’s University of London, London, United Kingdom
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4
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Zhang R, Xie J, Yuan X, Yu Y, Zhuang Y, Zhang F, Hou J, Liu Y, Huang W, Zhang M, Li J, Gong Q, Peng X. Newly discovered variants in unexplained neonatal encephalopathy. Mol Genet Genomic Med 2024; 12:e2354. [PMID: 38284441 PMCID: PMC10795097 DOI: 10.1002/mgg3.2354] [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: 04/12/2023] [Revised: 11/30/2023] [Accepted: 12/14/2023] [Indexed: 01/30/2024] Open
Abstract
BACKGROUND The genetic background of neonatal encephalopathy (NE) is complicated and early diagnosis is beneficial to optimizing therapeutic strategy for patients. METHODS NE Patients with unclear etiology received regular clinical tests including ammonia test, metabolic screening test, amplitude-integrated electroencephalographic (aEEG) monitoring, brain Magnetic Resonance Imaging (MRI) scanning, and genetic test. The protein structure change was predicted using Dynamut2 and RoseTTAFold. RESULTS 15 out of a total of 113 NE Patients were detected with newly reported pathogenic variants. In this sub-cohort, (1) seizure was the primary initial symptoms; (2) four patients had abnormal metabolic screening results, and two of them were also diagnosed with excessive blood ammonia concentration; (3) the brain MRI results were irregular in three infants and the brain waves were of moderate-severe abnormality in about a half of the patients. The novel pathogenic variants discovered in this study belonged to 12 genes, and seven of them were predicted to introduce a premature translation termination. In-silicon predictions showed that four variants were destructive to the protein structure of KCNQ2. CONCLUSION Our study expands the mutation spectrum of genes associated with NE and introduces new evidence for molecular diagnosis in this newborn illness.
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Affiliation(s)
- Rong Zhang
- Department of NeonatologyHunan Children's HospitalChangshaHunanChina
| | - Jingjing Xie
- Department of NeonatologyHunan Children's HospitalChangshaHunanChina
| | - Xiao Yuan
- Department of Laboratory DiagnosisChangsha Kingmed Center for Clinical LaboratoryChangshaHunanChina
| | - Yan Yu
- Department of Laboratory DiagnosisChangsha Kingmed Center for Clinical LaboratoryChangshaHunanChina
| | - Yan Zhuang
- Department of NeonatologyHunan Children's HospitalChangshaHunanChina
| | - Fan Zhang
- Department of NeonatologyHunan Children's HospitalChangshaHunanChina
| | - Jianfei Hou
- Department of Laboratory DiagnosisChangsha Kingmed Center for Clinical LaboratoryChangshaHunanChina
| | - Yanqin Liu
- Department of Laboratory DiagnosisChangsha Kingmed Center for Clinical LaboratoryChangshaHunanChina
| | - Weiqing Huang
- Department of NeonatologyHunan Children's HospitalChangshaHunanChina
| | - Min Zhang
- Department of NeonatologyHunan Children's HospitalChangshaHunanChina
| | - Junshuai Li
- Department of NeonatologyHunan Children's HospitalChangshaHunanChina
| | - Qiang Gong
- Department of Laboratory DiagnosisChangsha Kingmed Center for Clinical LaboratoryChangshaHunanChina
| | - Xiaoming Peng
- Department of NeonatologyHunan Children's HospitalChangshaHunanChina
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Huang Y, Ma D, Yang Z, Zhao Y, Guo J. Voltage-gated potassium channels KCNQs: Structures, mechanisms, and modulations. Biochem Biophys Res Commun 2023; 689:149218. [PMID: 37976835 DOI: 10.1016/j.bbrc.2023.149218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 10/19/2023] [Accepted: 11/03/2023] [Indexed: 11/19/2023]
Abstract
KCNQ (Kv7) channels are voltage-gated, phosphatidylinositol 4,5-bisphosphate- (PIP2-) modulated potassium channels that play essential roles in regulating the activity of neurons and cardiac myocytes. Hundreds of mutations in KCNQ channels are closely related to various cardiac and neurological disorders, such as long QT syndrome, epilepsy, and deafness, which makes KCNQ channels important drug targets. During the past several years, the application of single-particle cryo-electron microscopy (cryo-EM) technique in the structure determination of KCNQ channels has greatly advanced our understanding of their molecular mechanisms. In this review, we summarize the currently available structures of KCNQ channels, analyze their special voltage gating mechanism, and discuss their activation mechanisms by both the endogenous membrane lipid and the exogenous synthetic ligands. These structural studies of KCNQ channels will guide the development of drugs targeting KCNQ channels.
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Affiliation(s)
- Yuan Huang
- Department of Cardiology, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Demin Ma
- Department of Biophysics and Department of Neurology of the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Zhenni Yang
- Department of Biophysics and Department of Neurology of the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Yiwen Zhao
- The Key Laboratory of Neural and Vascular Biology, The Key Laboratory of New Drug Pharmacology and Toxicology, Department of Pharmacology, Ministry of Education, Hebei Medical University, Shijiazhuang, 050011, China
| | - Jiangtao Guo
- Department of Biophysics and Department of Neurology of the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310058, China.
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6
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Huang CN, Chen YM, Xiao XY, Zhou HL, Zhu J, Qin HM, Jiang X, Li Z, Zhuang T, Zhang GS. Pregabalin can interact synergistically with Kv7 channel openers to exert antinociception in mice. Eur J Pharmacol 2023:175870. [PMID: 37353189 DOI: 10.1016/j.ejphar.2023.175870] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 06/10/2023] [Accepted: 06/20/2023] [Indexed: 06/25/2023]
Abstract
Chronic pain is a common public health problem and remains an unmet medical need. Currently available analgesics usually have limited efficacy for the treatment of chronic pain, including neuropathic pain and persistent inflammatory pain, or they are accompanied by many adverse side effects. The voltage-gated calcium channel blocker (pregabalin) and potassium channel openers (flupirtine and retigabine) have been widely used for the management of chronic pain, but their effectiveness in combination is unclear. In this research, we evaluated the antinociceptive effects of pregabalin in combination with flupirtine or retigabine in carrageenan-induced inflammatory pain and paclitaxel-induced peripheral neuropathy in mice using the von Frey test. Isobolographic analysis indicated that pregabalin exerted synergistic antinociceptive effects when combined with flupirtine or retigabine in neuropathic and inflammatory pain models. Furthermore, the antinociceptive effects of pregabalin, flupirtine/retigabine, and their combinations were significantly attenuated by the Kv7 channel blocker XE991. The favored dose ratio between pregabalin and flupirtine/retigabine in combinations was also investigated. Finally, we evaluated the motor coordination of their combinations using the rotarod test, and the outcomes underpinned their safety. Collectively, our results support the potential use of pregabalin in combination with flupirtine or retigabine to alleviate chronic pain.
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Affiliation(s)
- Chao-Nan Huang
- Jiangsu Key Laboratory of Marine Biological Resources and Environment, Jiangsu Key Laboratory of Marine Pharmaceutical Compound Screening, School of Pharmacy, Jiangsu Ocean University, Lianyungang, 222005, China; Co-Innovation Center of Jiangsu Marine Bio-industry Technology, Jiangsu Ocean University, Lianyungang, 222005, China
| | - Yan-Ming Chen
- Jiangsu Key Laboratory of Marine Biological Resources and Environment, Jiangsu Key Laboratory of Marine Pharmaceutical Compound Screening, School of Pharmacy, Jiangsu Ocean University, Lianyungang, 222005, China; Co-Innovation Center of Jiangsu Marine Bio-industry Technology, Jiangsu Ocean University, Lianyungang, 222005, China
| | - Xin-Yi Xiao
- Jiangsu Key Laboratory of Marine Biological Resources and Environment, Jiangsu Key Laboratory of Marine Pharmaceutical Compound Screening, School of Pharmacy, Jiangsu Ocean University, Lianyungang, 222005, China; Co-Innovation Center of Jiangsu Marine Bio-industry Technology, Jiangsu Ocean University, Lianyungang, 222005, China
| | - Hui-Ling Zhou
- Jiangsu Key Laboratory of Marine Biological Resources and Environment, Jiangsu Key Laboratory of Marine Pharmaceutical Compound Screening, School of Pharmacy, Jiangsu Ocean University, Lianyungang, 222005, China
| | - Jin Zhu
- Jiangsu Key Laboratory of Marine Biological Resources and Environment, Jiangsu Key Laboratory of Marine Pharmaceutical Compound Screening, School of Pharmacy, Jiangsu Ocean University, Lianyungang, 222005, China; Co-Innovation Center of Jiangsu Marine Bio-industry Technology, Jiangsu Ocean University, Lianyungang, 222005, China
| | - Hui-Min Qin
- Jiangsu Key Laboratory of Marine Biological Resources and Environment, Jiangsu Key Laboratory of Marine Pharmaceutical Compound Screening, School of Pharmacy, Jiangsu Ocean University, Lianyungang, 222005, China
| | - Xue Jiang
- Jiangsu Key Laboratory of Marine Biological Resources and Environment, Jiangsu Key Laboratory of Marine Pharmaceutical Compound Screening, School of Pharmacy, Jiangsu Ocean University, Lianyungang, 222005, China
| | - Zongzheng Li
- Jiangsu Key Laboratory of Marine Biological Resources and Environment, Jiangsu Key Laboratory of Marine Pharmaceutical Compound Screening, School of Pharmacy, Jiangsu Ocean University, Lianyungang, 222005, China
| | - Tao Zhuang
- Jiangsu Key Laboratory of Marine Biological Resources and Environment, Jiangsu Key Laboratory of Marine Pharmaceutical Compound Screening, School of Pharmacy, Jiangsu Ocean University, Lianyungang, 222005, China; Co-Innovation Center of Jiangsu Marine Bio-industry Technology, Jiangsu Ocean University, Lianyungang, 222005, China.
| | - Gui-Sen Zhang
- Jiangsu Key Laboratory of Marine Biological Resources and Environment, Jiangsu Key Laboratory of Marine Pharmaceutical Compound Screening, School of Pharmacy, Jiangsu Ocean University, Lianyungang, 222005, China; Co-Innovation Center of Jiangsu Marine Bio-industry Technology, Jiangsu Ocean University, Lianyungang, 222005, China.
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7
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Bates A, Stowe RB, Travis EM, Cook LE, Dabney-Smith C, Lorigan GA. The role of native cysteine residues in the oligomerization of KCNQ1 channels. Biochem Biophys Res Commun 2023; 659:34-39. [PMID: 37031592 PMCID: PMC10170711 DOI: 10.1016/j.bbrc.2023.03.082] [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: 02/27/2023] [Accepted: 03/31/2023] [Indexed: 04/03/2023]
Abstract
KCNQ1, the major component of the slow-delayed rectifier potassium channel, is responsible for repolarization of cardiac action potential. Mutations in this channel can lead to a variety of diseases, most notably long QT syndrome. It is currently unknown how many of these mutations change channel function and structure on a molecular level. Since tetramerization is key to proper function and structure of the channel, it is likely that mutations modify the stability of KCNQ1 oligomers. Presently, the C-terminal domain of KCNQ1 has been noted as the driving force for oligomer formation. However, truncated versions of this protein lacking the C-terminal domain still tetramerize. Therefore, we explored the role of native cysteine residues in a truncated construct of human KCNQ1, amino acids 100-370, by blocking potential interactions of cysteines with a nitroxide based spin label. Mobility of the spin labels was investigated with continuous wave electron paramagnetic resonance (CW-EPR) spectroscopy. The oligomerization state was examined by gel electrophoresis. The data provide information on tetramerization of human KCNQ1 without the C-terminal domain. Specifically, how blocking the side chains of native cysteines residues reduces oligomerization. A better understanding of tetramer formation could provide improved understanding of the molecular etiology of long QT syndrome and other diseases related to KCNQ1.
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Affiliation(s)
- Alison Bates
- Department of Chemistry and Biochemistry, Miami University, 651 E. High Street, Oxford, OH, 45056, USA
| | - Rebecca B Stowe
- Department of Chemistry and Biochemistry, Miami University, 651 E. High Street, Oxford, OH, 45056, USA
| | - Elizabeth M Travis
- Department of Chemistry and Biochemistry, Miami University, 651 E. High Street, Oxford, OH, 45056, USA
| | - Lauryn E Cook
- Department of Chemistry and Biochemistry, Miami University, 651 E. High Street, Oxford, OH, 45056, USA
| | - Carole Dabney-Smith
- Department of Chemistry and Biochemistry, Miami University, 651 E. High Street, Oxford, OH, 45056, USA
| | - Gary A Lorigan
- Department of Chemistry and Biochemistry, Miami University, 651 E. High Street, Oxford, OH, 45056, USA.
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8
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Emerging mechanisms involving brain Kv7 channel in the pathogenesis of hypertension. Biochem Pharmacol 2022; 206:115318. [PMID: 36283445 DOI: 10.1016/j.bcp.2022.115318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 10/15/2022] [Accepted: 10/17/2022] [Indexed: 12/14/2022]
Abstract
Hypertension is a prevalent health problem inducing many organ damages. The pathogenesis of hypertension involves a complex integration of different organ systems including the brain. The elevated sympathetic nerve activity is closely related to the etiology of hypertension. Ion channels are critical regulators of neuronal excitability. Several mechanisms have been proposed to contribute to hypothalamic-driven elevated sympathetic activity, including altered ion channel function. Recent findings indicate one of the voltage-gated potassium channels, Kv7 channels (M channels), plays a vital role in regulating cardiovascular-related neurons activity, and the expression of Kv7 channels is downregulated in hypertension. This review highlights recent findings that the Kv7 channels in the brain, blood vessels, and kidneys are emerging targets involved in the pathogenesis of hypertension, suggesting new therapeutic targets for treating drug-resistant, neurogenic hypertension.
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9
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Lu H, Ding W, Xiao H, Dai M, Xue Y, Jia Z, Guo J, Wu M, Shen B, Zhao R. Association of the P441L KCNQ1 variant with severity of long QT syndrome and risk of cardiac events. Front Cardiovasc Med 2022; 9:922335. [PMID: 36386331 PMCID: PMC9659898 DOI: 10.3389/fcvm.2022.922335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2022] [Accepted: 09/12/2022] [Indexed: 11/27/2022] Open
Abstract
Dysfunction of potassium voltage-gated channel subfamily Q member 1 (KCNQ1) is a primary cause of long QT syndrome type 1 (LQT1). Here, we report a missense mutation P441L in KCNQ1 C-terminus of a 37-year-old woman with severe LQT1 phenotype. Variant P441L transporting to the plasma membrane and interacting with KCNE1 were both markedly decreased, leading to potassium efflux disorder and eventually LQT1. Mutations between the C-terminal helix A and helix B of KCNQ1 have linked with low cardiac event risk, however, we firstly find variant P441L causing a severe LQT1 phenotype with a high risk of cardiac events.
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Affiliation(s)
- Haoyang Lu
- Department of Cardiovascular Medicine, The First Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Wen Ding
- School of Basic Medical Sciences, Anhui Medical University, Hefei, China
| | - Hui Xiao
- Department of Cardiovascular Medicine, The First Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Manyu Dai
- Department of Cardiovascular Medicine, The First Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Yangcheng Xue
- Department of Cardiovascular Medicine, The First Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Zhuoran Jia
- Department of Cardiovascular Medicine, The First Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Jie Guo
- Department of Cardiovascular Medicine, The First Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Mengzuo Wu
- Department of Cardiovascular Medicine, The First Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Bing Shen
- School of Basic Medical Sciences, Anhui Medical University, Hefei, China
- Bing Shen,
| | - Ren Zhao
- Department of Cardiovascular Medicine, The First Affiliated Hospital of Anhui Medical University, Hefei, China
- *Correspondence: Ren Zhao,
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10
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Zheng H, Yan X, Li G, Lin H, Deng S, Zhuang W, Yao F, Lu Y, Xia X, Yuan H, Jin L, Yan Z. Proactive functional classification of all possible missense single-nucleotide variants in KCNQ4. Genome Res 2022; 32:1573-1584. [PMID: 35760561 PMCID: PMC9435748 DOI: 10.1101/gr.276562.122] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2022] [Accepted: 06/21/2022] [Indexed: 02/05/2023]
Abstract
Clinical exome sequencing has yielded extensive disease-related missense single-nucleotide variants (SNVs) of uncertain significance, leading to diagnostic uncertainty. KCNQ4 is one of the most commonly responsible genes for autosomal dominant nonsyndromic hearing loss. According to the gnomAD cohort, approximately one in 100 people harbors missense variants in KCNQ4 (missense variants with minor allele frequency > 0.1% were excluded), but most are of unknown consequence. To prospectively characterize the function of all 4085 possible missense SNVs of human KCNQ4, we recorded the whole-cell currents using the patch-clamp technique and categorized 1068 missense SNVs as loss of function, as well as 728 loss-of-function SNVs located in the transmembrane domains. Further, to mimic the heterozygous condition in Deafness nonsyndromic autosomal dominant 2 (DFNA2) patients caused by KCNQ4 variants, we coexpressed loss-of-function variants with wild-type KCNQ4 and found 516 variants showed impaired or only partially rescued heterogeneous channel function. Overall, our functional classification is highly concordant with the auditory phenotypes in Kcnq4 mutant mice and the assessments of pathogenicity in clinical variant interpretations. Taken together, our results provide strong functional evidence to support the pathogenicity classification of newly discovered KCNQ4 missense variants in clinical genetic testing.
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Affiliation(s)
- Honglan Zheng
- Human Phenome Institute, School of Life Sciences, Fudan University, Shanghai 200438, China
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200438, China
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen 518132, China
| | - Xinhao Yan
- Human Phenome Institute, School of Life Sciences, Fudan University, Shanghai 200438, China
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200438, China
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen 518132, China
| | - Guanluan Li
- Human Phenome Institute, School of Life Sciences, Fudan University, Shanghai 200438, China
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200438, China
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen 518132, China
| | - Hengwei Lin
- Human Phenome Institute, School of Life Sciences, Fudan University, Shanghai 200438, China
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200438, China
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen 518132, China
| | - Siqi Deng
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen 518132, China
| | - Wenhui Zhuang
- Human Phenome Institute, School of Life Sciences, Fudan University, Shanghai 200438, China
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200438, China
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen 518132, China
| | - Fuqiang Yao
- Human Phenome Institute, School of Life Sciences, Fudan University, Shanghai 200438, China
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200438, China
| | - Yu Lu
- Institute of Rare Diseases, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Xin Xia
- Human Phenome Institute, School of Life Sciences, Fudan University, Shanghai 200438, China
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200438, China
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen 518132, China
| | - Huijun Yuan
- Institute of Rare Diseases, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Li Jin
- Human Phenome Institute, School of Life Sciences, Fudan University, Shanghai 200438, China
| | - Zhiqiang Yan
- Human Phenome Institute, School of Life Sciences, Fudan University, Shanghai 200438, China
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200438, China
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen 518132, China
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11
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Yang ND, Kanyo R, Zhao L, Li J, Kang PW, Dou AK, White KM, Shi J, Nerbonne JM, Kurata HT, Cui J. Electro-mechanical coupling of KCNQ channels is a target of epilepsy-associated mutations and retigabine. SCIENCE ADVANCES 2022; 8:eabo3625. [PMID: 35857840 PMCID: PMC9299555 DOI: 10.1126/sciadv.abo3625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Accepted: 06/07/2022] [Indexed: 06/15/2023]
Abstract
KCNQ2 and KCNQ3 form the M-channels that are important in regulating neuronal excitability. Inherited mutations that alter voltage-dependent gating of M-channels are associated with neonatal epilepsy. In the homolog KCNQ1 channel, two steps of voltage sensor activation lead to two functionally distinct open states, the intermediate-open (IO) and activated-open (AO), which define the gating, physiological, and pharmacological properties of KCNQ1. However, whether the M-channel shares the same mechanism is unclear. Here, we show that KCNQ2 and KCNQ3 feature only a single conductive AO state but with a conserved mechanism for the electro-mechanical (E-M) coupling between voltage sensor activation and pore opening. We identified some epilepsy-linked mutations in KCNQ2 and KCNQ3 that disrupt E-M coupling. The antiepileptic drug retigabine rescued KCNQ3 currents that were abolished by a mutation disrupting E-M coupling, suggesting that modulating the E-M coupling in KCNQ channels presents a potential strategy for antiepileptic therapy.
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Affiliation(s)
- Nien-Du Yang
- 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
| | - Richard Kanyo
- Department of Pharmacology, Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada
| | - Lu Zhao
- 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
| | - Jingru Li
- Department of Pharmacology, Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada
| | - 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
| | - Alex Kelly 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
| | - 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
| | - 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
| | - Jeanne M. Nerbonne
- Departments of Developmental Biology and Internal Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Harley T. Kurata
- Department of Pharmacology, Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada
| | - 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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12
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Willegems K, Eldstrom J, Kyriakis E, Ataei F, Sahakyan H, Dou Y, Russo S, Van Petegem F, Fedida D. Structural and electrophysiological basis for the modulation of KCNQ1 channel currents by ML277. Nat Commun 2022; 13:3760. [PMID: 35768468 PMCID: PMC9243137 DOI: 10.1038/s41467-022-31526-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 06/17/2022] [Indexed: 01/10/2023] Open
Abstract
The KCNQ1 ion channel plays critical physiological roles in electrical excitability and K+ recycling in organs including the heart, brain, and gut. Loss of function is relatively common and can cause sudden arrhythmic death, sudden infant death, epilepsy and deafness. Here, we report cryogenic electron microscopic (cryo-EM) structures of Xenopus KCNQ1 bound to Ca2+/Calmodulin, with and without the KCNQ1 channel activator, ML277. A single binding site for ML277 was identified, localized to a pocket lined by the S4-S5 linker, S5 and S6 helices of two separate subunits. Several pocket residues are not conserved in other KCNQ isoforms, explaining specificity. MD simulations and point mutations support this binding location for ML277 in open and closed channels and reveal that prevention of inactivation is an important component of the activator effect. Our work provides direction for therapeutic intervention targeting KCNQ1 loss of function pathologies including long QT interval syndrome and seizures. KCNQ1 channels are active in heart, brain and gut. Functional loss causes epilepsy and sudden arrhythmic death. Here, authors describe a key activator drug binding site, explaining isoform and drug selectivity, and point the way for new drug design.
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Affiliation(s)
- Katrien Willegems
- Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, BC, Canada.,Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
| | - Jodene Eldstrom
- Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, BC, Canada
| | - Efthimios Kyriakis
- Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, BC, Canada
| | - Fariba Ataei
- Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, BC, Canada
| | - Harutyun Sahakyan
- National Center for Biotechnology Information, National Library of Medicine, National Institutes for Health, Bethesda, MD, USA
| | - Ying Dou
- Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, BC, Canada
| | - Sophia Russo
- Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, BC, Canada
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada.
| | - David Fedida
- Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, BC, Canada.
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13
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PIP 2-dependent coupling of voltage sensor and pore domains in K v7.2 channel. Commun Biol 2021; 4:1189. [PMID: 34650221 PMCID: PMC8517023 DOI: 10.1038/s42003-021-02729-3] [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: 08/17/2020] [Accepted: 09/23/2021] [Indexed: 01/10/2023] Open
Abstract
Phosphatidylinositol-4,5-bisphosphate (PIP2) is a signaling lipid which regulates voltage-gated Kv7/KCNQ potassium channels. Altered PIP2 sensitivity of neuronal Kv7.2 channel is involved in KCNQ2 epileptic encephalopathy. However, the molecular action of PIP2 on Kv7.2 gating remains largely elusive. Here, we use molecular dynamics simulations and electrophysiology to characterize PIP2 binding sites in a human Kv7.2 channel. In the closed state, PIP2 localizes to the periphery of the voltage-sensing domain (VSD). In the open state, PIP2 binds to 4 distinct interfaces formed by the cytoplasmic ends of the VSD, the gate, intracellular helices A and B and their linkers. PIP2 binding induces bilayer-interacting conformation of helices A and B and the correlated motion of the VSD and the pore domain, whereas charge-neutralizing mutations block this coupling and reduce PIP2 sensitivity of Kv7.2 channels by disrupting PIP2 binding. These findings reveal the allosteric role of PIP2 in Kv7.2 channel activation. Pant et al. describe the mechanism by which PIP2 might regulate homomeric Kv7.2 channels. They identify sites important in the binding of the PIP2 lipid to Kv7.2 channels and propose that the PIP2 binding to a specific site results in the coupling between the voltage sensor domain (VSD) and pore domain (PD), which stabilizes the open state of the channel.
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14
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Chen X, Zhang Y, Ren X, Su Q, Liu Y, Dang X, Qin Y, Yang X, Xing Z, Shen Y, Wang Y, Bai Z, Yeh ETH, Wu H, Qi Y. The SUMO-specific protease SENP2 plays an essential role in the regulation of Kv7.2 and Kv7.3 potassium channels. J Biol Chem 2021; 297:101183. [PMID: 34509475 PMCID: PMC8488601 DOI: 10.1016/j.jbc.2021.101183] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2021] [Revised: 08/28/2021] [Accepted: 09/08/2021] [Indexed: 11/04/2022] Open
Abstract
Sentrin/small ubiquitin-like modifier (SUMO)-specific protease 2 (SENP2)-deficient mice develop spontaneous seizures in early life because of a marked reduction in M currents, which regulate neuronal membrane excitability. We have previously shown that hyper-SUMOylation of the Kv7.2 and Kv7.3 channels is critically involved in the regulation of the M currents conducted by these potassium voltage-gated channels. Here, we show that hyper-SUMOylation of the Kv7.2 and Kv7.3 proteins reduced binding to the lipid secondary messenger PIP2. CaM1 has been shown to be tethered to the Kv7 subunits via hydrophobic motifs in its C termini and implicated in the channel assembly. Mutation of the SUMOylation sites on Kv7.2 and Kv7.3 specifically resulted in decreased binding to CaM1 and enhanced CaM1-mediated assembly of Kv7.2 and Kv7.3, whereas hyper-SUMOylation of Kv7.2 and Kv7.3 inhibited channel assembly. SENP2-deficient mice exhibited increased acetylcholine levels in the brain and the heart tissue because of increases in the vagal tone induced by recurrent seizures. The SENP2-deficient mice develop seizures followed by a period of sinus pauses or atrioventricular conduction blocks. Chronic administration of the parasympathetic blocker atropine or unilateral vagotomy significantly prolonged the life of the SENP2-deficient mice. Furthermore, we showed that retigabine, an M-current opener, reduced the transcription of SUMO-activating enzyme SAE1 and inhibited SUMOylation of the Kv7.2 and Kv7.3 channels, and also prolonged the life of SENP2-deficient mice. Taken together, the previously demonstrated roles of PIP2, CaM1, and retigabine on the regulation of Kv7.2 and Kv7.3 channel function can be explained by their roles in regulating SUMOylation of this critical potassium channel.
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Affiliation(s)
- Xu Chen
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Developing of Endangered Chinese Crude Drugs in Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, Shaanxi, China
| | - Yuhong Zhang
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Developing of Endangered Chinese Crude Drugs in Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, Shaanxi, China
| | - Xiang Ren
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Developing of Endangered Chinese Crude Drugs in Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, Shaanxi, China
| | - Qi Su
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Developing of Endangered Chinese Crude Drugs in Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, Shaanxi, China
| | - Yan Liu
- School of Life Sciences & Research Center for Peptide Drugs, Yan'an University, Yan'an, Shaanxi, China
| | - Xing Dang
- College of Chemistry and Chemical Engineering, Xi'an University of Science and Technology, Xi'an, Shaanxi, China
| | - Yuanyuan Qin
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Developing of Endangered Chinese Crude Drugs in Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, Shaanxi, China
| | - Xinyi Yang
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Developing of Endangered Chinese Crude Drugs in Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, Shaanxi, China
| | - Zhengcao Xing
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Developing of Endangered Chinese Crude Drugs in Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, Shaanxi, China
| | - Yajie Shen
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Developing of Endangered Chinese Crude Drugs in Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, Shaanxi, China
| | - Yaya Wang
- College of Chemistry and Chemical Engineering, Xi'an University of Science and Technology, Xi'an, Shaanxi, China
| | - Zhantao Bai
- School of Life Sciences & Research Center for Peptide Drugs, Yan'an University, Yan'an, Shaanxi, China
| | - Edward T H Yeh
- Department of Internal Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Hongmei Wu
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Developing of Endangered Chinese Crude Drugs in Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, Shaanxi, China.
| | - Yitao Qi
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Developing of Endangered Chinese Crude Drugs in Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, Shaanxi, China.
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15
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Yuan JH, Estacion M, Mis MA, Tanaka BS, Schulman BR, Chen L, Liu S, Dib-Hajj FB, Dib-Hajj SD, Waxman SG. KCNQ variants and pain modulation: a missense variant in Kv7.3 contributes to pain resilience. Brain Commun 2021; 3:fcab212. [PMID: 34557669 PMCID: PMC8454204 DOI: 10.1093/braincomms/fcab212] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 07/13/2021] [Accepted: 07/29/2021] [Indexed: 12/02/2022] Open
Abstract
There is a pressing need for understanding of factors that confer resilience to pain. Gain-of-function mutations in sodium channel Nav1.7 produce hyperexcitability of dorsal root ganglion neurons underlying inherited erythromelalgia, a human genetic model of neuropathic pain. While most individuals with erythromelalgia experience excruciating pain, occasional outliers report more moderate pain. These differences in pain profiles in blood-related erythromelalgia subjects carrying the same pain-causative Nav1.7 mutation and markedly different pain experience provide a unique opportunity to investigate potential genetic factors that contribute to inter-individual variability in pain. We studied a patient with inherited erythromelalgia and a Nav1.7 mutation (c.4345T>G, p. F1449V) with severe pain as is characteristic of most inherited erythromelalgia patients, and her mother who carries the same Nav1.7 mutation with a milder pain phenotype. Detailed six-week daily pain diaries of pain episodes confirmed their distinct pain profiles. Electrophysiological studies on subject-specific induced pluripotent stem cell-derived sensory neurons from each of these patients showed that the excitability of these cells paralleled their pain phenotype. Whole-exome sequencing identified a missense variant (c.2263C>T, p. D755N) in KCNQ3 (Kv7.3) in the pain resilient mother. Voltage-clamp recordings showed that co-expression of Kv7.2-wild type (WT)/Kv7.3-D755N channels produced larger M-currents than that of Kv7.2-WT/Kv7.3-WT. The difference in excitability of the patient-specific induced pluripotent stem cell-derived sensory neurons was mimicked by modulating M-current levels using the dynamic clamp and a model of the mutant Kv7.2-WT/Kv7.3-D755N channels. These results show that a 'pain-in-a-dish' model can be used to explicate genetic contributors to pain, and confirm that KCNQ variants can confer pain resilience via an effect on peripheral sensory neurons.
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Affiliation(s)
- Jun-Hui Yuan
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06520, USA
- Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06520, USA
- Center for Rehabilitation Research, VA Connecticut Healthcare System, West Haven, CT 06516, USA
| | - Mark Estacion
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06520, USA
- Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06520, USA
- Center for Rehabilitation Research, VA Connecticut Healthcare System, West Haven, CT 06516, USA
| | - Malgorzata A Mis
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06520, USA
- Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06520, USA
- Center for Rehabilitation Research, VA Connecticut Healthcare System, West Haven, CT 06516, USA
| | - Brian S Tanaka
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06520, USA
- Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06520, USA
- Center for Rehabilitation Research, VA Connecticut Healthcare System, West Haven, CT 06516, USA
| | - Betsy R Schulman
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06520, USA
- Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06520, USA
- Center for Rehabilitation Research, VA Connecticut Healthcare System, West Haven, CT 06516, USA
| | - Lubin Chen
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06520, USA
- Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06520, USA
- Center for Rehabilitation Research, VA Connecticut Healthcare System, West Haven, CT 06516, USA
| | - Shujun Liu
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06520, USA
- Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06520, USA
- Center for Rehabilitation Research, VA Connecticut Healthcare System, West Haven, CT 06516, USA
| | - Fadia B Dib-Hajj
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06520, USA
- Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06520, USA
- Center for Rehabilitation Research, VA Connecticut Healthcare System, West Haven, CT 06516, USA
| | - Sulayman D Dib-Hajj
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06520, USA
- Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06520, USA
- Center for Rehabilitation Research, VA Connecticut Healthcare System, West Haven, CT 06516, USA
| | - Stephen G Waxman
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06520, USA
- Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06520, USA
- Center for Rehabilitation Research, VA Connecticut Healthcare System, West Haven, CT 06516, USA
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16
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Dwivedi D, Bhalla US. Physiology and Therapeutic Potential of SK, H, and M Medium AfterHyperPolarization Ion Channels. Front Mol Neurosci 2021; 14:658435. [PMID: 34149352 PMCID: PMC8209339 DOI: 10.3389/fnmol.2021.658435] [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: 01/25/2021] [Accepted: 04/13/2021] [Indexed: 12/19/2022] Open
Abstract
SK, HCN, and M channels are medium afterhyperpolarization (mAHP)-mediating ion channels. The three channels co-express in various brain regions, and their collective action strongly influences cellular excitability. However, significant diversity exists in the expression of channel isoforms in distinct brain regions and various subcellular compartments, which contributes to an equally diverse set of specific neuronal functions. The current review emphasizes the collective behavior of the three classes of mAHP channels and discusses how these channels function together although they play specialized roles. We discuss the biophysical properties of these channels, signaling pathways that influence the activity of the three mAHP channels, various chemical modulators that alter channel activity and their therapeutic potential in treating various neurological anomalies. Additionally, we discuss the role of mAHP channels in the pathophysiology of various neurological diseases and how their modulation can alleviate some of the symptoms.
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Affiliation(s)
- Deepanjali Dwivedi
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bengaluru, India.,Department of Neurobiology, Harvard Medical School, Boston, MA, United States.,Stanley Center at the Broad, Cambridge, MA, United States
| | - Upinder S Bhalla
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bengaluru, India
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17
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Urrutia J, Aguado A, Gomis-Perez C, Muguruza-Montero A, Ballesteros OR, Zhang J, Nuñez E, Malo C, Chung HJ, Leonardo A, Bergara A, Villarroel A. An epilepsy-causing mutation leads to co-translational misfolding of the Kv7.2 channel. BMC Biol 2021; 19:109. [PMID: 34020651 PMCID: PMC8138981 DOI: 10.1186/s12915-021-01040-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 04/29/2021] [Indexed: 12/21/2022] Open
Abstract
Background The amino acid sequence of proteins generally carries all the necessary information for acquisition of native conformations, but the vectorial nature of translation can additionally determine the folding outcome. Such consideration is particularly relevant in human diseases associated to inherited mutations leading to structural instability, aggregation, and degradation. Mutations in the KCNQ2 gene associated with human epilepsy have been suggested to cause misfolding of the encoded Kv7.2 channel. Although the effect on folding of mutations in some domains has been studied, little is known of the way pathogenic variants located in the calcium responsive domain (CRD) affect folding. Here, we explore how a Kv7.2 mutation (W344R) located in helix A of the CRD and associated with hereditary epilepsy interferes with channel function. Results We report that the epilepsy W344R mutation within the IQ motif of CRD decreases channel function, but contrary to other mutations at this site, it does not impair the interaction with Calmodulin (CaM) in vitro, as monitored by multiple in vitro binding assays. We find negligible impact of the mutation on the structure of the complex by molecular dynamic computations. In silico studies revealed two orientations of the side chain, which are differentially populated by WT and W344R variants. Binding to CaM is impaired when the mutated protein is produced in cellulo but not in vitro, suggesting that this mutation impedes proper folding during translation within the cell by forcing the nascent chain to follow a folding route that leads to a non-native configuration, and thereby generating non-functional ion channels that fail to traffic to proper neuronal compartments. Conclusions Our data suggest that the key pathogenic mechanism of Kv7.2 W344R mutation involves the failure to adopt a configuration that can be recognized by CaM in vivo but not in vitro. Supplementary Information The online version contains supplementary material available at 10.1186/s12915-021-01040-1.
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Affiliation(s)
- Janire Urrutia
- Instituto Biofisika, CSIC-UPV/EHU, 48940, Leioa, Spain.,Present address: Department of Physiology, Faculty of Medicine and Nursery, UPV/EHU, 48940, Leioa, Spain
| | | | - Carolina Gomis-Perez
- Instituto Biofisika, CSIC-UPV/EHU, 48940, Leioa, Spain.,Present address: Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT, USA
| | | | | | - Jiaren Zhang
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Eider Nuñez
- Instituto Biofisika, CSIC-UPV/EHU, 48940, Leioa, Spain
| | | | - Hee Jung Chung
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Aritz Leonardo
- Departamento de Física Aplicada II, Universidad del País Vasco, UPV/EHU, 48940, Leioa, Spain.,Donostia International Physics Center, 20018, Donostia, Spain
| | - Aitor Bergara
- Centro de Física de Materiales CFM, CSIC-UPV/EHU, 20018, Donostia, Spain.,Donostia International Physics Center, 20018, Donostia, Spain.,Departmento de Materia Condensada, Universidad del País Vasco, UPV/EHU, 48940, Leioa, Spain
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18
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van der Horst J, Rognant S, Abbott GW, Ozhathil LC, Hägglund P, Barrese V, Chuang CY, Jespersen T, Davies MJ, Greenwood IA, Gourdon P, Aalkjær C, Jepps TA. Dynein regulates Kv7.4 channel trafficking from the cell membrane. J Gen Physiol 2021; 153:211752. [PMID: 33533890 PMCID: PMC7863719 DOI: 10.1085/jgp.202012760] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2020] [Revised: 12/21/2020] [Accepted: 01/08/2021] [Indexed: 12/15/2022] Open
Abstract
The dynein motor protein transports proteins away from the cell membrane along the microtubule network. Recently, we found the microtubule network was important for regulating the membrane abundance of voltage-gated Kv7.4 potassium channels in vascular smooth muscle. Here, we aimed to investigate the influence of dynein on the microtubule-dependent internalization of the Kv7.4 channel. Patch-clamp recordings from HEK293B cells showed Kv7.4 currents were increased after inhibiting dynein function with ciliobrevin D or by coexpressing p50/dynamitin, which specifically interferes with dynein motor function. Mutation of a dynein-binding site in the Kv7.4 C terminus increased the Kv7.4 current and prevented p50 interference. Structured illumination microscopy, proximity ligation assays, and coimmunoprecipitation showed colocalization of Kv7.4 and dynein in mesenteric artery myocytes. Ciliobrevin D enhanced mesenteric artery relaxation to activators of Kv7.2–Kv7.5 channels and increased membrane abundance of Kv7.4 protein in isolated smooth muscle cells and HEK293B cells. Ciliobrevin D failed to enhance the negligible S-1–mediated relaxations after morpholino-mediated knockdown of Kv7.4. Mass spectrometry revealed an interaction of dynein with caveolin-1, confirmed using proximity ligation and coimmunoprecipitation assays, which also provided evidence for interaction of caveolin-1 with Kv7.4, confirming that Kv7.4 channels are localized to caveolae in mesenteric artery myocytes. Lastly, cholesterol depletion reduced the interaction of Kv7.4 with caveolin-1 and dynein while increasing the overall membrane expression of Kv7.4, although it attenuated the Kv7.4 current in oocytes and interfered with the action of ciliobrevin D and channel activators in arterial segments. Overall, this study shows that dynein can traffic Kv7.4 channels in vascular smooth muscle in a mechanism dependent on cholesterol-rich caveolae.
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Affiliation(s)
| | - Salomé Rognant
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA
| | | | - Per Hägglund
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Vincenzo Barrese
- St. George's, University of London, London, UK.,Department of Neuroscience, Reproductive Science and Dentistry, University of Naples "Federico II," Naples, Italy
| | - Christine Y Chuang
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Thomas Jespersen
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Michael J Davies
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | - Pontus Gourdon
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Medical Sciences, Lund University, Lund, Sweden
| | - Christian Aalkjær
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Thomas A Jepps
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
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19
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Lo YC, Lin CL, Fang WY, Lőrinczi B, Szatmári I, Chang WH, Fülöp F, Wu SN. Effective Activation by Kynurenic Acid and Its Aminoalkylated Derivatives on M-Type K + Current. Int J Mol Sci 2021; 22:ijms22031300. [PMID: 33525680 PMCID: PMC7865226 DOI: 10.3390/ijms22031300] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 01/25/2021] [Accepted: 01/26/2021] [Indexed: 12/24/2022] Open
Abstract
Kynurenic acid (KYNA, 4-oxoquinoline-2-carboxylic acid), an intermediate of the tryptophan metabolism, has been recognized to exert different neuroactive actions; however, the need of how it or its aminoalkylated amide derivative N-(2-(dimethylamino)ethyl)-3-(morpholinomethyl)-4-oxo-1,4-dihydroquinoline-2-carboxamide (KYNA-A4) exerts any effects on ion currents in excitable cells remains largely unmet. In this study, the investigations of how KYNA and other structurally similar KYNA derivatives have any adjustments on different ionic currents in pituitary GH3 cells and hippocampal mHippoE-14 neurons were performed by patch-clamp technique. KYNA or KYNA-A4 increased the amplitude of M-type K+ current (IK(M)) and concomitantly enhanced the activation time course of the current. The EC50 value required for KYNA- or KYNA-A4 -stimulated IK(M) was yielded to be 18.1 or 6.4 μM, respectively. The presence of KYNA or KYNA-A4 shifted the relationship of normalized IK(M)-conductance versus membrane potential to more depolarized potential with no change in the gating charge of the current. The voltage-dependent hysteretic area of IK(M) elicited by long-lasting triangular ramp pulse was observed in GH3 cells and that was increased during exposure to KYNA or KYNA-A4. In cell-attached current recordings, addition of KYNA raised the open probability of M-type K+ channels, along with increased mean open time of the channel. Cell exposure to KYNA or KYNA-A4 mildly inhibited delayed-rectifying K+ current; however, neither erg-mediated K+ current, hyperpolarization-activated cation current, nor voltage-gated Na+ current in GH3 cells was changed by KYNA or KYNA-A4. Under whole-cell, current-clamp recordings, exposure to KYNA or KYNA-A4 diminished the frequency of spontaneous action potentials; moreover, their reduction in firing frequency was attenuated by linopirdine, yet not by iberiotoxin or apamin. In hippocampal mHippoE-14 neurons, the addition of KYNA also increased the IK(M) amplitude effectively. Taken together, the actions presented herein would be one of the noticeable mechanisms through which they modulate functional activities of excitable cells occurring in vivo.
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Affiliation(s)
- Yi-Ching Lo
- Department of Pharmacology, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 80708, Taiwan; (W.-Y.F.); (W.-H.C.)
- Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung 80708, Taiwan
- Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
- Correspondence: (Y.-C.L.); (S.-N.W.); Tel.: +886-7-3234686 (Y.-C.L.); +886-6-2353535-5334 (S.-N.W.); Fax: +886-7-3234686 (Y.-C.L.); +886-6-2362780 (S.-N.W.)
| | - Chih-Lung Lin
- Department of Neurosurgery, Kaohsiung Medical University Hospital, Kaohsiung 80708, Taiwan;
- Department of Neurosurgery, College of Medicine, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
| | - Wei-Yu Fang
- Department of Pharmacology, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 80708, Taiwan; (W.-Y.F.); (W.-H.C.)
| | - Bálint Lőrinczi
- Institute of Pharmaceutical Chemistry, University of Szeged, Eötvös u. 6, H-6720 Szeged, Hungary; (B.L.); (I.S.); (F.F.)
| | - István Szatmári
- Institute of Pharmaceutical Chemistry, University of Szeged, Eötvös u. 6, H-6720 Szeged, Hungary; (B.L.); (I.S.); (F.F.)
| | - Wan-Hsuan Chang
- Department of Pharmacology, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 80708, Taiwan; (W.-Y.F.); (W.-H.C.)
- Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
| | - Ferenc Fülöp
- Institute of Pharmaceutical Chemistry, University of Szeged, Eötvös u. 6, H-6720 Szeged, Hungary; (B.L.); (I.S.); (F.F.)
- MTA-SZTE Stereochemistry Research Group, Hungarian Academy of Sciences, Eötvös u. 6, H-6720 Szeged, Hungary
| | - Sheng-Nan Wu
- Institute of Basic Medical Sciences, National Cheng Kung University Medical College, Tainan City 70101, Taiwan
- Department of Physiology, National Cheng Kung University Medical College, Tainan City 70101, Taiwan
- Correspondence: (Y.-C.L.); (S.-N.W.); Tel.: +886-7-3234686 (Y.-C.L.); +886-6-2353535-5334 (S.-N.W.); Fax: +886-7-3234686 (Y.-C.L.); +886-6-2362780 (S.-N.W.)
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20
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Abstract
Kv7.1-Kv7.5 (KCNQ1-5) K+ channels are voltage-gated K+ channels with major roles in neurons, muscle cells and epithelia where they underlie physiologically important K+ currents, such as neuronal M current and cardiac IKs. Specific biophysical properties of Kv7 channels make them particularly well placed to control the activity of excitable cells. Indeed, these channels often work as 'excitability breaks' and are targeted by various hormones and modulators to regulate cellular activity outputs. Genetic deficiencies in all five KCNQ genes result in human excitability disorders, including epilepsy, arrhythmias, deafness and some others. Not surprisingly, this channel family attracts considerable attention as potential drug targets. Here we will review biophysical properties and tissue expression profile of Kv7 channels, discuss recent advances in the understanding of their structure as well as their role in various neurological, cardiovascular and other diseases and pathologies. We will also consider a scope for therapeutic targeting of Kv7 channels for treatment of the above health conditions.
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21
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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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22
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Baculis BC, Zhang J, Chung HJ. The Role of K v7 Channels in Neural Plasticity and Behavior. Front Physiol 2020; 11:568667. [PMID: 33071824 PMCID: PMC7530275 DOI: 10.3389/fphys.2020.568667] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 08/28/2020] [Indexed: 12/12/2022] Open
Abstract
Activity-dependent persistent changes in neuronal intrinsic excitability and synaptic strength are widely thought to underlie learning and memory. Voltage-gated KCNQ/Kv7 potassium channels have been of great interest as the potential targets for memory disorders due to the beneficial effects of their antagonists in cognition. Importantly, de novo dominant mutations in their neuronal subunits KCNQ2/Kv7.2 and KCNQ3/Kv7.3 are associated with epilepsy and neurodevelopmental disorder characterized by developmental delay and intellectual disability. The role of Kv7 channels in neuronal excitability and epilepsy has been extensively studied. However, their functional significance in neural plasticity, learning, and memory remains largely unknown. Here, we review recent studies that support the emerging roles of Kv7 channels in intrinsic and synaptic plasticity, and their contributions to cognition and behavior.
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Affiliation(s)
- Brian C Baculis
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Jiaren Zhang
- Department of Molecular Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Hee Jung Chung
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL, United States.,Department of Molecular Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
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23
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Xu Parks X, Qudsi H, Braun C, Lopes CMB. The auxiliary subunit KCNE1 regulates KCNQ1 channel response to sustained calcium-dependent PKC activation. PLoS One 2020; 15:e0237591. [PMID: 32833978 PMCID: PMC7446858 DOI: 10.1371/journal.pone.0237591] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 07/29/2020] [Indexed: 11/18/2022] Open
Abstract
The slow cardiac delayed rectifier current (IKs) is formed by KCNQ1 and KCNE1 subunits and is one of the major repolarizing currents in the heart. Decrease of IKs currents either due to inherited mutations or pathological remodeling is associated with increased risk for cardiac arrhythmias and sudden death. Ca2+-dependent PKC isoforms (cPKC) are chronically activated in heart disease and diabetes. Recently, we found that sustained stimulation of the calcium-dependent PKCβII isoform leads to decrease in KCNQ1 subunit membrane localization and KCNQ1/KCNE1 channel activity, although the role of KCNE1 in this regulation was not explored. Here, we show that the auxiliary KCNE1 subunit expression is necessary for channel internalization. A mutation in a KCNE1 phosphorylation site (KCNE1(S102A)) abolished channel internalization in both heterologous expression systems and cardiomyocytes. Altogether, our results suggest that KCNE1(S102) phosphorylation by PKCβII leads to KCNQ1/KCNE1 channel internalization in response to sustained PKC stimulus, while leaving KCNQ1 homomeric channels in the membrane. This preferential internalization is expected to have strong impact on cardiac repolarization. Our results suggest that KCNE1(S102) is an important anti-arrhythmic drug target to prevent IKs pathological remodeling leading to cardiac arrhythmias.
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Affiliation(s)
- Xiaorong Xu Parks
- Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, United States of America
| | - Haani Qudsi
- Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, United States of America
| | - Chen Braun
- Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, United States of America
| | - Coeli M. B. Lopes
- Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, United States of America
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24
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Abstract
Kv7 channels (Kv7.1-7.5) are voltage-gated K+ channels that can be modulated by five β-subunits (KCNE1-5). Kv7.1-KCNE1 channels produce the slow-delayed rectifying K+ current, IKs, which is important during the repolarization phase of the cardiac action potential. Kv7.2-7.5 are predominantly neuronally expressed and constitute the muscarinic M-current and control the resting membrane potential in neurons. Kv7.1 produces drastically different currents as a result of modulation by KCNE subunits. This flexibility allows the Kv7.1 channel to have many roles depending on location and assembly partners. The pharmacological sensitivity of Kv7.1 channels differs from that of Kv7.2-7.5 and is largely dependent upon the number of β-subunits present in the channel complex. As a result, the development of pharmaceuticals targeting Kv7.1 is problematic. This review discusses the roles and the mechanisms by which different signaling pathways affect Kv7.1 and KCNE channels and could potentially provide different ways of targeting the channel.
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Affiliation(s)
- Emely Thompson
- Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada;
| | - Jodene Eldstrom
- Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada;
| | - David Fedida
- Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada;
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25
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van der Horst J, Greenwood IA, Jepps TA. Cyclic AMP-Dependent Regulation of Kv7 Voltage-Gated Potassium Channels. Front Physiol 2020; 11:727. [PMID: 32695022 PMCID: PMC7338754 DOI: 10.3389/fphys.2020.00727] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 06/04/2020] [Indexed: 01/08/2023] Open
Abstract
Voltage-gated Kv7 potassium channels, encoded by KCNQ genes, have major physiological impacts cardiac myocytes, neurons, epithelial cells, and smooth muscle cells. Cyclic adenosine monophosphate (cAMP), a well-known intracellular secondary messenger, can activate numerous downstream effector proteins, generating downstream signaling pathways that regulate many functions in cells. A role for cAMP in ion channel regulation has been established, and recent findings show that cAMP signaling plays a role in Kv7 channel regulation. Although cAMP signaling is recognized to regulate Kv7 channels, the precise molecular mechanism behind the cAMP-dependent regulation of Kv7 channels is complex. This review will summarize recent research findings that support the mechanisms of cAMP-dependent regulation of Kv7 channels.
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Affiliation(s)
- Jennifer van der Horst
- Vascular Biology Group, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Iain A Greenwood
- Molecular and Clinical Sciences Institute, St. George's University of London, London, United Kingdom
| | - Thomas A Jepps
- Vascular Biology Group, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
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26
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Li J, Maghera J, Lamothe SM, Marco EJ, Kurata HT. Heteromeric Assembly of Truncated Neuronal Kv7 Channels: Implications for Neurologic Disease and Pharmacotherapy. Mol Pharmacol 2020; 98:192-202. [DOI: 10.1124/mol.120.119644] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 06/11/2020] [Indexed: 12/19/2022] Open
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27
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Vigil FA, Carver CM, Shapiro MS. Pharmacological Manipulation of K v 7 Channels as a New Therapeutic Tool for Multiple Brain Disorders. Front Physiol 2020; 11:688. [PMID: 32636759 PMCID: PMC7317068 DOI: 10.3389/fphys.2020.00688] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 05/27/2020] [Indexed: 12/12/2022] Open
Abstract
K v 7 ("M-type," KCNQ) K+ currents, play dominant roles in controlling neuronal excitability. They act as a "brake" against hyperexcitable states in the central and peripheral nervous systems. Pharmacological augmentation of M current has been developed for controlling epileptic seizures, although current pharmacological tools are uneven in practical usefulness. Lately, however, M-current "opener" compounds have been suggested to be efficacious in preventing brain damage after multiple types of insults/diseases, such as stroke, traumatic brain injury, drug addiction and mood disorders. In this review, we will discuss what is known to date on these efforts and identify gaps in our knowledge regarding the link between M current and therapeutic potential for these disorders. We will outline the preclinical experiments that are yet to be performed to demonstrate the likelihood of success of this approach in human trials. Finally, we also address multiple pharmacological tools available to manipulate different K v 7 subunits and the relevant evidence for translational application in the clinical use for disorders of the central nervous system and multiple types of brain insults. We feel there to be great potential for manipulation of K v 7 channels as a novel therapeutic mode of intervention in the clinic, and that the paucity of existing therapies obligates us to perform further research, so that patients can soon benefit from such therapeutic approaches.
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Affiliation(s)
- Fabio A Vigil
- Department of Cellular and Integrative Physiology, University of Texas Health San Antonio, San Antonio, TX, United States
| | - Chase M Carver
- Department of Cellular and Integrative Physiology, University of Texas Health San Antonio, San Antonio, TX, United States
| | - Mark S Shapiro
- Department of Cellular and Integrative Physiology, University of Texas Health San Antonio, San Antonio, TX, United States
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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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29
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Zhang J, Kim EC, Chen C, Procko E, Pant S, Lam K, Patel J, Choi R, Hong M, Joshi D, Bolton E, Tajkhorshid E, Chung HJ. Identifying mutation hotspots reveals pathogenetic mechanisms of KCNQ2 epileptic encephalopathy. Sci Rep 2020; 10:4756. [PMID: 32179837 PMCID: PMC7075958 DOI: 10.1038/s41598-020-61697-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 03/02/2020] [Indexed: 11/08/2022] Open
Abstract
Kv7 channels are enriched at the axonal plasma membrane where their voltage-dependent potassium currents suppress neuronal excitability. Mutations in Kv7.2 and Kv7.3 subunits cause epileptic encephalopathy (EE), yet the underlying pathogenetic mechanism is unclear. Here, we used novel statistical algorithms and structural modeling to identify EE mutation hotspots in key functional domains of Kv7.2 including voltage sensing S4, the pore loop and S6 in the pore domain, and intracellular calmodulin-binding helix B and helix B-C linker. Characterization of selected EE mutations from these hotspots revealed that L203P at S4 induces a large depolarizing shift in voltage dependence of Kv7.2 channels and L268F at the pore decreases their current densities. While L268F severely reduces expression of heteromeric channels in hippocampal neurons without affecting internalization, K552T and R553L mutations at distal helix B decrease calmodulin-binding and axonal enrichment. Importantly, L268F, K552T, and R553L mutations disrupt current potentiation by increasing phosphatidylinositol 4,5-bisphosphate (PIP2), and our molecular dynamics simulation suggests PIP2 interaction with these residues. Together, these findings demonstrate that each EE variant causes a unique combination of defects in Kv7 channel function and neuronal expression, and suggest a critical need for both prediction algorithms and experimental interrogations to understand pathophysiology of Kv7-associated EE.
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Affiliation(s)
- Jiaren Zhang
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
| | - Eung Chang Kim
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
| | - Congcong Chen
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
- Department of Statistics, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
| | - Erik Procko
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
| | - Shashank Pant
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
| | - Kin Lam
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
| | - Jaimin Patel
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
| | - Rebecca Choi
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
| | - Mary Hong
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
| | - Dhruv Joshi
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
| | - Eric Bolton
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
| | - Emad Tajkhorshid
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
| | - Hee Jung Chung
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA.
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA.
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30
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Allen NM, Weckhuysen S, Gorman K, King MD, Lerche H. Genetic potassium channel-associated epilepsies: Clinical review of the K v family. Eur J Paediatr Neurol 2020; 24:105-116. [PMID: 31932120 DOI: 10.1016/j.ejpn.2019.12.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 12/06/2019] [Indexed: 12/22/2022]
Abstract
Next-generation sequencing has enhanced discovery of many disease-associated genes in previously unexplained epilepsies, mainly in developmental and epileptic encephalopathies and familial epilepsies. We now classify these disorders according to the underlying molecular pathways, which encompass a diverse array of cellular and sub-cellular compartments/signalling processes including voltage-gated ion-channel defects. With the aim to develop and increase the use of precision medicine therapies, understanding the pathogenic mechanisms and consequences of disease-causing variants has gained major relevance in clinical care. The super-family of voltage-gated potassium channels is the largest and most diverse family among the ion channels, encompassing approximately 80 genes. Key potassium channelopathies include those affecting the KV, KCa and Kir families, a significant proportion of which have been implicated in neurological disease. As for other ion channel disorders, different pathogenic variants within any individual voltage-gated potassium channel gene tend to affect channel protein function differently, causing heterogeneous clinical phenotypes. The focus of this review is to summarise recent clinical developments regarding the key voltage-gated potassium (KV) family-related epilepsies, which now encompasses approximately 12 established disease-associated genes, from the KCNA-, KCNB-, KCNC-, KCND-, KCNV-, KCNQ- and KCNH-subfamilies.
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Affiliation(s)
- Nicholas M Allen
- Department of Paediatrics, National University of Ireland, Galway, Ireland; Department of Paediatrics (Neurology), Galway University Hospital, Ireland; Regenerative Medicine Institute (REMEDI), National University of Ireland, Galway, Ireland.
| | - Sarah Weckhuysen
- Neurogenetics Group, Center for Molecular Neurology, VIB-University of Antwerp, Antwerp, Belgium; Department of Neurology, University Hospital Antwerp, Antwerp, Belgium
| | - Kathleen Gorman
- Department of Paediatric Neurology & Clinical Neurophysiology, Children's Health Ireland at Temple Street, Dublin 1, Ireland; University College Dublin School of Medicine and Medical Science, University College, Dublin, Ireland
| | - Mary D King
- Department of Paediatric Neurology & Clinical Neurophysiology, Children's Health Ireland at Temple Street, Dublin 1, Ireland; University College Dublin School of Medicine and Medical Science, University College, Dublin, Ireland
| | - Holger Lerche
- Department of Neurology and Epileptology, Hertie Institute of Clinical Brain Research, University of Tubingen, Germany
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Kurakami K, Norota I, Nasu F, Ohshima S, Nagasawa Y, Konno Y, Obara Y, Ishii K. KCNQ1 is internalized by activation of α1 adrenergic receptors. Biochem Pharmacol 2019; 169:113628. [DOI: 10.1016/j.bcp.2019.113628] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 08/30/2019] [Indexed: 01/25/2023]
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Lin Y, Zhao T, He S, Huang J, Liu Q, Yang Z, Qin J, Yu N, Lu H, Lin X. Compound and heterozygous mutations of KCNQ1 in long QT syndrome with familial history of unexplained sudden death: Identified by analysis of whole exome sequencing and predisposing genes. Ann Noninvasive Electrocardiol 2019; 25:e12694. [PMID: 31565860 PMCID: PMC7358849 DOI: 10.1111/anec.12694] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Accepted: 08/05/2019] [Indexed: 12/23/2022] Open
Abstract
Introduction Long QT syndrome (LQTS) increases the risk of life‐threatening arrhythmia in young individuals with structurally normal hearts. Sixteen genes such as the KCNQ1, KCNH2, and SCN5A have been reported for association with LQTS. Case presentation We identified the compound heterozygous mutations in the KCNQ1 gene at c. G527A (p.W176X) and c.G1765A (p.G589S) predicted as “damaging.” The in‐silico analysis showed that when compared to the characteristics of mRNA and protein of wild‐type KCNQ1, the mRNA of c.G527A mutation was significantly different in the centroid secondary structure. The subunit coded by W176X would lose the transmembrane domains S3–S6 and helices A‐D. The protein secondary structure of G589S was slightly shortened in helix structure; the protein physics‐chemical parameters of W176X and G589S significantly and slightly changed, respectively. Conclusions The compound heterozygous mutations of W176X and G589S coexisting in KCNQ1 gene of homologous chromosomes, resulting in more severe phenotype, are the likely pathogenic and genetic risks of LQTS and USD in this Chinese family.
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Affiliation(s)
- Yubi Lin
- Department of Cardiology and Cardiovascular Intervention, Interventional Medical Center, The Fifth Affiliated Hospital of Sun Yat-sen University, Zhuhai, China.,Guangdong Provincial Key Laboratory of Biomedical Imaging and Guangdong Provincial Engineering Research Center of Molecular Imaging, The Fifth Affiliated Hospital, Sun Yat-sen University, Zhuhai, China.,Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangdong Cardiovascular Institute, Guangdong Geriatrics Institute, Guangzhou, China
| | - Ting Zhao
- Department of Cardiology and Cardiovascular Intervention, Interventional Medical Center, The Fifth Affiliated Hospital of Sun Yat-sen University, Zhuhai, China
| | - Siqi He
- The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Jiana Huang
- The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | | | - Zhe Yang
- Department of Cardiology and Cardiovascular Intervention, Interventional Medical Center, The Fifth Affiliated Hospital of Sun Yat-sen University, Zhuhai, China
| | - Jiading Qin
- Department of Cardiology and Cardiovascular Intervention, Interventional Medical Center, The Fifth Affiliated Hospital of Sun Yat-sen University, Zhuhai, China
| | - Nan Yu
- Department of Clinical Laboratory, Zhujiang Hospital of Southern Medical University, Guangzhou, China
| | - Hongyun Lu
- Department of Endocrinology, The Fifth Affiliated Hospital of Sun Yat-sen University, Zhuhai, China
| | - Xiufang Lin
- Department of Cardiology and Cardiovascular Intervention, Interventional Medical Center, The Fifth Affiliated Hospital of Sun Yat-sen University, Zhuhai, China
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Genetic intolerance analysis as a tool for protein science. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1862:183058. [PMID: 31494120 DOI: 10.1016/j.bbamem.2019.183058] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2019] [Revised: 08/21/2019] [Accepted: 08/30/2019] [Indexed: 01/04/2023]
Abstract
Recent advances in whole genome and exome sequencing have dramatically increased the database of human gene variations. There are now enough sequenced human exomes and genomes to begin to identify gene variations that are notable because they are NOT observed in sequenced human genomes, apparently because they are subject to "purifying selection", exemplifying genetic intolerance. Such "dysprocreative" gene variations are embryonic lethal or prevent reproduction through any one of a number of possible mechanisms. Here we review an emerging quantitative approach, "Missense Tolerance Ratio" (MTR) analysis, that is used to assess protein-encoding gene (cDNA) sequence intolerance to missense mutations based on analysis of the >100 K and growing number of currently available human genome and exome sequences. This approach is already useful for analyzing intolerance to mutations in cDNA segments with a resolution on the order of 90 bases. Moreover, as the number of sequenced genomes/exomes increases by orders of magnitude it may eventually be possible to assess mutational tolerance in a statistically robust manner at or near single site resolution. Here we focus on how cDNA intolerance analysis complements other bioinformatic methods to illuminate structure-folding-function relationships for the encoded proteins. A set of disease-linked membrane proteins is employed to provide examples.
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Lauritano A, Moutton S, Longobardi E, Tran Mau‐Them F, Laudati G, Nappi P, Soldovieri MV, Ambrosino P, Cataldi M, Jouan T, Lehalle D, Maurey H, Philippe C, Miceli F, Vitobello A, Taglialatela M. A novel homozygous KCNQ3 loss-of-function variant causes non-syndromic intellectual disability and neonatal-onset pharmacodependent epilepsy. Epilepsia Open 2019; 4:464-475. [PMID: 31440727 PMCID: PMC6698674 DOI: 10.1002/epi4.12353] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 07/04/2019] [Accepted: 07/28/2019] [Indexed: 12/18/2022] Open
Abstract
OBJECTIVE Heterozygous variants in KCNQ2 or, more rarely, KCNQ3 genes are responsible for early-onset developmental/epileptic disorders characterized by heterogeneous clinical presentation and course, genetic transmission, and prognosis. While familial forms mostly include benign epilepsies with seizures starting in the neonatal or early-infantile period, de novo variants in KCNQ2 or KCNQ3 have been described in sporadic cases of early-onset encephalopathy (EOEE) with pharmacoresistant seizures, various age-related pathological EEG patterns, and moderate/severe developmental impairment. All pathogenic variants in KCNQ2 or KCNQ3 occur in heterozygosity. The aim of this work was to report the clinical, molecular, and functional properties of a new KCNQ3 variant found in homozygous configuration in a 9-year-old girl with pharmacodependent neonatal-onset epilepsy and non-syndromic intellectual disability. METHODS Exome sequencing was used for genetic investigation. KCNQ3 transcript and subunit expression in fibroblasts was analyzed with quantitative real-time PCR and Western blotting or immunofluorescence, respectively. Whole-cell patch-clamp electrophysiology was used for functional characterization of mutant subunits. RESULTS A novel single-base duplication in exon 12 of KCNQ3 (NM_004519.3:c.1599dup) was found in homozygous configuration in the proband born to consanguineous healthy parents; this frameshift variant introduced a premature termination codon (PTC), thus deleting a large part of the C-terminal region. Mutant KCNQ3 transcript and protein abundance was markedly reduced in primary fibroblasts from the proband, consistent with nonsense-mediated mRNA decay. The variant fully abolished the ability of KCNQ3 subunits to assemble into functional homomeric or heteromeric channels with KCNQ2 subunits. SIGNIFICANCE The present results indicate that a homozygous KCNQ3 loss-of-function variant is responsible for a severe phenotype characterized by neonatal-onset pharmacodependent seizures, with developmental delay and intellectual disability. They also reveal difference in genetic and pathogenetic mechanisms between KCNQ2- and KCNQ3-related epilepsies, a crucial observation for patients affected with EOEE and/or developmental disabilities.
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Affiliation(s)
- Anna Lauritano
- Division of Pharmacology, Department of NeuroscienceUniversity of Naples “Federico II”NaplesItaly
| | - Sebastien Moutton
- Reference Center for Developmental Anomalies, Department of Medical GeneticsDijon University HospitalDijonFrance
- INSERM U1231, LNC UMR1231 GADBurgundy UniversityDijonFrance
| | - Elena Longobardi
- Division of Pharmacology, Department of NeuroscienceUniversity of Naples “Federico II”NaplesItaly
| | - Frédéric Tran Mau‐Them
- INSERM U1231, LNC UMR1231 GADBurgundy UniversityDijonFrance
- Laboratoire de Génétique, Innovation en Diagnostic Génomique des Maladies Rares UF6254, Plateau Technique de BiologieCHU DijonDijonFrance
| | - Giusy Laudati
- Division of Pharmacology, Department of NeuroscienceUniversity of Naples “Federico II”NaplesItaly
| | - Piera Nappi
- Division of Pharmacology, Department of NeuroscienceUniversity of Naples “Federico II”NaplesItaly
| | | | - Paolo Ambrosino
- Division of Pharmacology, Department of Science and TechnologyUniversity of SannioBeneventoItaly
| | - Mauro Cataldi
- Division of Pharmacology, Department of NeuroscienceUniversity of Naples “Federico II”NaplesItaly
| | - Thibaud Jouan
- INSERM U1231, LNC UMR1231 GADBurgundy UniversityDijonFrance
- Laboratoire de Génétique, Innovation en Diagnostic Génomique des Maladies Rares UF6254, Plateau Technique de BiologieCHU DijonDijonFrance
| | - Daphné Lehalle
- Reference Center for Developmental Anomalies, Department of Medical GeneticsDijon University HospitalDijonFrance
- INSERM U1231, LNC UMR1231 GADBurgundy UniversityDijonFrance
| | - Hélène Maurey
- Service de Neurologie PédiatriqueAPHP, Hôpital Universitaire BicêtreLe Kremlin‐BicêtreFrance
| | - Christophe Philippe
- INSERM U1231, LNC UMR1231 GADBurgundy UniversityDijonFrance
- Laboratoire de Génétique, Innovation en Diagnostic Génomique des Maladies Rares UF6254, Plateau Technique de BiologieCHU DijonDijonFrance
| | - Francesco Miceli
- Division of Pharmacology, Department of NeuroscienceUniversity of Naples “Federico II”NaplesItaly
| | - Antonio Vitobello
- INSERM U1231, LNC UMR1231 GADBurgundy UniversityDijonFrance
- Laboratoire de Génétique, Innovation en Diagnostic Génomique des Maladies Rares UF6254, Plateau Technique de BiologieCHU DijonDijonFrance
| | - Maurizio Taglialatela
- Division of Pharmacology, Department of NeuroscienceUniversity of Naples “Federico II”NaplesItaly
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Meisel E, Tobelaim W, Dvir M, Haitin Y, Peretz A, Attali B. Inactivation gating of Kv7.1 channels does not involve concerted cooperative subunit interactions. Channels (Austin) 2019; 12:89-99. [PMID: 29451064 PMCID: PMC5972808 DOI: 10.1080/19336950.2018.1441649] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Inactivation is an intrinsic property of numerous voltage-gated K+ (Kv) channels and can occur by N-type or/and C-type mechanisms. N-type inactivation is a fast, voltage independent process, coupled to activation, with each inactivation particle of a tetrameric channel acting independently. In N-type inactivation, a single inactivation particle is necessary and sufficient to occlude the pore. C-type inactivation is a slower process, involving the outermost region of the pore and is mediated by a concerted, highly cooperative interaction between all four subunits. Inactivation of Kv7.1 channels does not exhibit the hallmarks of N- and C-type inactivation. Inactivation of WT Kv7.1 channels can be revealed by hooked tail currents that reflects the recovery from a fast and voltage-independent inactivation process. However, several Kv7.1 mutants such as the pore mutant L273F generate an additional voltage-dependent slow inactivation. The subunit interactions during this slow inactivation gating remain unexplored. The goal of the present study was to study the nature of subunit interactions along Kv7.1 inactivation gating, using concatenated tetrameric Kv7.1 channel and introducing sequentially into each of the four subunits the slow inactivating pore mutation L273F. Incorporating an incremental number of inactivating mutant subunits did not affect the inactivation kinetics but slowed down the recovery kinetics from inactivation. Results indicate that Kv7.1 inactivation gating is not compatible with a concerted cooperative process. Instead, adding an inactivating subunit L273F into the Kv7.1 tetramer incrementally stabilizes the inactivated state, which suggests that like for activation gating, Kv7.1 slow inactivation gating is not a concerted process.
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Affiliation(s)
- Eshcar Meisel
- a Department of Physiology & Pharmacology , the Sackler Faculty of Medicine and Sagol School of Neurosciences, Tel Aviv University , Tel Aviv , Israel
| | - William Tobelaim
- a Department of Physiology & Pharmacology , the Sackler Faculty of Medicine and Sagol School of Neurosciences, Tel Aviv University , Tel Aviv , Israel
| | - Meidan Dvir
- a Department of Physiology & Pharmacology , the Sackler Faculty of Medicine and Sagol School of Neurosciences, Tel Aviv University , Tel Aviv , Israel
| | - Yoni Haitin
- a Department of Physiology & Pharmacology , the Sackler Faculty of Medicine and Sagol School of Neurosciences, Tel Aviv University , Tel Aviv , Israel
| | - Asher Peretz
- a Department of Physiology & Pharmacology , the Sackler Faculty of Medicine and Sagol School of Neurosciences, Tel Aviv University , Tel Aviv , Israel
| | - Bernard Attali
- a Department of Physiology & Pharmacology , the Sackler Faculty of Medicine and Sagol School of Neurosciences, Tel Aviv University , Tel Aviv , Israel
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36
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Alaimo A, Etxeberria A, Gómez-Posada JC, Gomis-Perez C, Fernández-Orth J, Malo C, Villarroel A. Lack of correlation between surface expression and currents in epileptogenic AB-calmodulin binding domain Kv7.2 potassium channel mutants. Channels (Austin) 2019; 12:299-310. [PMID: 30126342 PMCID: PMC6161613 DOI: 10.1080/19336950.2018.1511512] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Heteromers of Kv7.2/Kv7.3 subunits constitute the main substrate of the neuronal M-current that limits neuronal hyper-excitability and firing frequency. Calmodulin (CaM) binding is essential for surface expression of Kv7 channels, and disruption of this interaction leads to diseases ranging from mild epilepsy to early onset encephalopathy. In this study, we addressed the impact of a charge neutralizing mutation located at the periphery of helix B (K526N). We found that, CaM binding and surface expression was impaired, although current amplitude was not altered. Currents were reduced at a faster rate after activation of a voltage-dependent phosphatase, suggesting that phosphatidylinositol-4,5-bisphosphate (PIP2) binding was weaker. In contrast, a charge neutralizing mutation located at the periphery of helix A (R333Q) did not affect CaM binding, but impaired trafficking and led to a reduction in current amplitude. Taken together, these results suggest that disruption of CaM-dependent or CaM-independent trafficking of Kv7.2/Kv7.3 channels can lead to pathology regardless of the consequences on the macroscopic ionic flow through the channel.
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Affiliation(s)
- Alessandro Alaimo
- a Instituto Biofisika , Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU , Leioa , Spain
| | - Ainhoa Etxeberria
- a Instituto Biofisika , Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU , Leioa , Spain
| | - Juan Camilo Gómez-Posada
- a Instituto Biofisika , Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU , Leioa , Spain
| | - Carolina Gomis-Perez
- a Instituto Biofisika , Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU , Leioa , Spain
| | - Juncal Fernández-Orth
- a Instituto Biofisika , Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU , Leioa , Spain
| | - Covadonga Malo
- a Instituto Biofisika , Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU , Leioa , Spain
| | - Alvaro Villarroel
- a Instituto Biofisika , Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU , Leioa , Spain
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Ramasubramanian S, Rudy Y. The Structural Basis of IKs Ion-Channel Activation: Mechanistic Insights from Molecular Simulations. Biophys J 2019; 114:2584-2594. [PMID: 29874609 PMCID: PMC6129186 DOI: 10.1016/j.bpj.2018.04.023] [Citation(s) in RCA: 20] [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: 02/07/2018] [Revised: 03/28/2018] [Accepted: 04/13/2018] [Indexed: 11/19/2022] Open
Abstract
Relating ion channel (iCh) structural dynamics to physiological function remains a challenge. Current experimental and computational techniques have limited ability to explore this relationship in atomistic detail over physiological timescales. A framework associating iCh structure to function is necessary for elucidating normal and disease mechanisms. We formulated a modeling schema that overcomes the limitations of current methods through applications of artificial intelligence machine learning. Using this approach, we studied molecular processes that underlie human IKs voltage-mediated gating. IKs malfunction underlies many debilitating and life-threatening diseases. Molecular components of IKs that underlie its electrophysiological function include KCNQ1 (a pore-forming tetramer) and KCNE1 (an auxiliary subunit). Simulations, using the IKs structure-function model, reproduced experimentally recorded saturation of gating-charge displacement at positive membrane voltages, two-step voltage sensor (VS) movement shown by fluorescence, iCh gating statistics, and current-voltage relationship. Mechanistic insights include the following: 1) pore energy profile determines iCh subconductance; 2) the entire protein structure, not limited to the pore, contributes to pore energy and channel subconductance; 3) interactions with KCNE1 result in two distinct VS movements, causing gating-charge saturation at positive membrane voltages and current activation delay; and 4) flexible coupling between VS and pore permits pore opening at lower VS positions, resulting in sequential gating. The new modeling approach is applicable to atomistic scale studies of other proteins on timescales of physiological function.
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Affiliation(s)
- Smiruthi Ramasubramanian
- Department of Biomedical Engineering and Cardiac Bioelectricity and Arrhythmia Center, Washington University in St. Louis, St. Louis, Missouri
| | - Yoram Rudy
- Department of Biomedical Engineering and Cardiac Bioelectricity and Arrhythmia Center, Washington University in St. Louis, St. Louis, Missouri.
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38
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Archer CR, Enslow BT, Taylor AB, De la Rosa V, Bhattacharya A, Shapiro MS. A mutually induced conformational fit underlies Ca 2+-directed interactions between calmodulin and the proximal C terminus of KCNQ4 K + channels. J Biol Chem 2019; 294:6094-6112. [PMID: 30808708 PMCID: PMC6463706 DOI: 10.1074/jbc.ra118.006857] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 02/24/2019] [Indexed: 11/06/2022] Open
Abstract
Calmodulin (CaM) conveys intracellular Ca2+ signals to KCNQ (Kv7, "M-type") K+ channels and many other ion channels. Whether this "calmodulation" involves a dramatic structural rearrangement or only slight perturbations of the CaM/KCNQ complex is as yet unclear. A consensus structural model of conformational shifts occurring between low nanomolar and physiologically high intracellular [Ca2+] is still under debate. Here, we used various techniques of biophysical chemical analyses to investigate the interactions between CaM and synthetic peptides corresponding to the A and B domains of the KCNQ4 subtype. We found that in the absence of CaM, the peptides are disordered, whereas Ca2+/CaM imposed helical structure on both KCNQ A and B domains. Isothermal titration calorimetry revealed that Ca2+/CaM has higher affinity for the B domain than for the A domain of KCNQ2-4 and much higher affinity for the B domain when prebound with the A domain. X-ray crystallography confirmed that these discrete peptides spontaneously form a complex with Ca2+/CaM, similar to previous reports of CaM binding KCNQ-AB domains that are linked together. Microscale thermophoresis and heteronuclear single-quantum coherence NMR spectroscopy indicated the C-lobe of Ca2+-free CaM to interact with the KCNQ4 B domain (Kd ∼10-20 μm), with increasing Ca2+ molar ratios shifting the CaM-B domain interactions via only the CaM C-lobe to also include the N-lobe. Our findings suggest that in response to increased Ca2+, CaM undergoes lobe switching that imposes a dramatic mutually induced conformational fit to both the proximal C terminus of KCNQ4 channels and CaM, likely underlying Ca2+-dependent regulation of KCNQ gating.
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Affiliation(s)
- Crystal R Archer
- From the Departments of Cell and Integrative Physiology, University of Texas Health San Antonio, San Antonio, Texas 78229; Departments of Biochemistry and Structural Biology, University of Texas Health San Antonio, San Antonio, Texas 78229
| | - Benjamin T Enslow
- the Long School of Medicine, University of Texas Health San Antonio, San Antonio, Texas 78229
| | - Alexander B Taylor
- Departments of Biochemistry and Structural Biology, University of Texas Health San Antonio, San Antonio, Texas 78229
| | - Victor De la Rosa
- From the Departments of Cell and Integrative Physiology, University of Texas Health San Antonio, San Antonio, Texas 78229
| | - Akash Bhattacharya
- Departments of Biochemistry and Structural Biology, University of Texas Health San Antonio, San Antonio, Texas 78229
| | - Mark S Shapiro
- From the Departments of Cell and Integrative Physiology, University of Texas Health San Antonio, San Antonio, Texas 78229.
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39
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McDonald SK, Levitz TS, Valiyaveetil FI. A Shared Mechanism for the Folding of Voltage-Gated K + Channels. Biochemistry 2019; 58:1660-1671. [PMID: 30793887 DOI: 10.1021/acs.biochem.9b00068] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In this study, we probe the folding of KvAP, a voltage-gated K+ (Kv) channel. The KvAP channel, though of archaebacterial origin, is structurally and functionally similar to eukaryotic Kv channels. An advantage of the KvAP channel is that it can be folded in vitro from an extensively unfolded state and the folding can be controlled by temperature. We utilize these properties of the KvAP channel to separately study the membrane insertion and the tetramerization stages during folding. We use two quantitative assays: a Cys PEGylation assay to monitor membrane insertion and a cross-linking assay to monitor tetramerization. We show that during folding the KvAP polypeptide is rapidly inserted into the lipid bilayer with a "native-like" topology. We identify a segment at the C-terminus that is important for multimerization of the KvAP channel. We show that this C-terminal domain forms a dimer, which raises the possibility that the tetramerization of the KvAP channel proceeds through a dimer of dimers pathway. Our studies show that the in vitro folding of the KvAP channel mirrors aspects of the cellular assembly pathway for voltage-gated K+ channels and therefore suggest that evolutionarily distinct Kv channels share a common folding pathway. The pathway for the folding and assembly of a Kv channel is of central importance as defects in this pathway have been implicated in the etiology of several disease states. Our studies indicate that the KvAP channel provides an experimentally tractable system for elucidating the folding mechanism of Kv channels.
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Affiliation(s)
- Sarah K McDonald
- Program in Chemical Biology, Department of Physiology and Pharmacology , Oregon Health & Science University , 3181 Southwest Sam Jackson Park Road , Portland , Oregon 97239 , United States
| | - Talya S Levitz
- Program in Chemical Biology, Department of Physiology and Pharmacology , Oregon Health & Science University , 3181 Southwest Sam Jackson Park Road , Portland , Oregon 97239 , United States
| | - Francis I Valiyaveetil
- Program in Chemical Biology, Department of Physiology and Pharmacology , Oregon Health & Science University , 3181 Southwest Sam Jackson Park Road , Portland , Oregon 97239 , United States
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40
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Barros F, Pardo LA, Domínguez P, Sierra LM, de la Peña P. New Structures and Gating of Voltage-Dependent Potassium (Kv) Channels and Their Relatives: A Multi-Domain and Dynamic Question. Int J Mol Sci 2019; 20:ijms20020248. [PMID: 30634573 PMCID: PMC6359393 DOI: 10.3390/ijms20020248] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 12/30/2018] [Accepted: 01/07/2019] [Indexed: 12/15/2022] Open
Abstract
Voltage-dependent potassium channels (Kv channels) are crucial regulators of cell excitability that participate in a range of physiological and pathophysiological processes. These channels are molecular machines that display a mechanism (known as gating) for opening and closing a gate located in a pore domain (PD). In Kv channels, this mechanism is triggered and controlled by changes in the magnitude of the transmembrane voltage sensed by a voltage-sensing domain (VSD). In this review, we consider several aspects of the VSD–PD coupling in Kv channels, and in some relatives, that share a common general structure characterized by a single square-shaped ion conduction pore in the center, surrounded by four VSDs located at the periphery. We compile some recent advances in the knowledge of their architecture, based in cryo-electron microscopy (cryo-EM) data for high-resolution determination of their structure, plus some new functional data obtained with channel variants in which the covalent continuity between the VSD and PD modules has been interrupted. These advances and new data bring about some reconsiderations about the use of exclusively a classical electromechanical lever model of VSD–PD coupling by some Kv channels, and open a view of the Kv-type channels as allosteric machines in which gating may be dynamically influenced by some long-range interactional/allosteric mechanisms.
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Affiliation(s)
- Francisco Barros
- Departamento de Bioquímica y Biología Molecular, Universidad de Oviedo, Edificio Santiago Gascón, Campus de El Cristo, 33006 Oviedo, Asturias, Spain.
| | - Luis A Pardo
- Oncophysiology Group, Max Planck Institute of Experimental Medicine, Hermann-Rein-Strasse 3, 37075 Göttingen, Germany.
| | - Pedro Domínguez
- Departamento de Bioquímica y Biología Molecular, Universidad de Oviedo, Edificio Santiago Gascón, Campus de El Cristo, 33006 Oviedo, Asturias, Spain.
| | - Luisa Maria Sierra
- Departamento de Biología Funcional (Area de Genética), Instituto Universitario de Oncología del Principado de Asturias (IUOPA), Universidad de Oviedo, 33006 Oviedo, Asturias, Spain.
| | - Pilar de la Peña
- Departamento de Bioquímica y Biología Molecular, Universidad de Oviedo, Edificio Santiago Gascón, Campus de El Cristo, 33006 Oviedo, Asturias, Spain.
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Strigli A, Raab C, Hessler S, Huth T, Schuldt AJT, Alzheimer C, Friedrich T, Burridge PW, Luedde M, Schwake M. Doxorubicin induces caspase-mediated proteolysis of KV7.1. Commun Biol 2018; 1:155. [PMID: 30302399 PMCID: PMC6162258 DOI: 10.1038/s42003-018-0162-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 08/31/2018] [Indexed: 12/13/2022] Open
Abstract
Kv7.1 (KCNQ1) coassembles with KCNE1 to generate the cardiac IKs-channel. Gain- and loss-of-function mutations in KCNQ1 are associated with cardiac arrhthymias, highlighting the importance of modulating IKs activity for cardiac function. Here, we report proteolysis of Kv7.1 as an irreversible posttranslational modification. The identification of two C-terminal fragments of Kv7.1 led us to identify an aspartate critical for the generation of one of the fragments and caspases as responsible for mediating proteolysis. Activating caspases reduces Kv7.1/KCNE1 currents, which is abrogated in cells expressing caspase-resistant channels. Enhanced cleavage of Kv7.1 can be detected for the LQT mutation G460S, which is located adjacent to the cleavage site, whereas a calmodulin-binding-deficient mutation impairs cleavage. Application of apoptotic stimuli or doxorubicin-induced cardiotoxicity provokes caspase-mediated cleavage of endogenous IKs in human cardiomyocytes. In summary, caspases are novel regulatory components of IKs channels that may have important implications for the molecular mechanism of doxorubicin-induced cardiotoxicity. Anne Strigli et al. report that the voltage-gated potassium channel Kv7.1 undergoes caspase-mediated proteolytic cleavage, which reduces its cardiac activity. Their findings implicate caspases as regulators of the IKs channel complex, which may have implications for understanding drug-induced cardiotoxicity.
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Affiliation(s)
- Anne Strigli
- Institute of Biochemistry, Christian Albrechts University of Kiel, Otto-Hahn-Platz 9, 24118, Kiel, Germany
| | - Christian Raab
- Institute of Biochemistry, Christian Albrechts University of Kiel, Otto-Hahn-Platz 9, 24118, Kiel, Germany
| | - Sabine Hessler
- Institute of Physiology and Pathophysiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Universitätsstr. 17, 91054, Erlangen, Germany
| | - Tobias Huth
- Institute of Physiology and Pathophysiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Universitätsstr. 17, 91054, Erlangen, Germany
| | - Adam J T Schuldt
- Department of Pharmacology and Center for Pharmacogenomics, Feinberg School of Medicine, Northwestern University, 320 East Superior Street, Searle Building 8-450, Chicago, IL, 60611, USA
| | - Christian Alzheimer
- Institute of Physiology and Pathophysiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Universitätsstr. 17, 91054, Erlangen, Germany
| | - Thomas Friedrich
- Institut für Chemie PC 14, Technische Universität Berlin, Straße des 17. Juni 135, 10623, Berlin, Germany
| | - Paul W Burridge
- Department of Pharmacology and Center for Pharmacogenomics, Feinberg School of Medicine, Northwestern University, 320 East Superior Street, Searle Building 8-450, Chicago, IL, 60611, USA
| | - Mark Luedde
- Department of Internal Medicine III, University Hospital Schleswig-Holstein, Campus Kiel, Arnold-Heller-Str. 3, 24105, Kiel, Germany
| | - Michael Schwake
- Institute of Biochemistry, Christian Albrechts University of Kiel, Otto-Hahn-Platz 9, 24118, Kiel, Germany. .,Faculty of Chemistry/Biochemistry III, University of Bielefeld, Universitätsstr. 25, 33615, Bielefeld, Germany. .,Department of Neurology, Northwestern University Feinberg School of Medicine, 303 East Chicago Avenue, Chicago, IL, 60611-4296, USA.
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42
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Calmodulin: A Multitasking Protein in Kv7.2 Potassium Channel Functions. Biomolecules 2018; 8:biom8030057. [PMID: 30022004 PMCID: PMC6164012 DOI: 10.3390/biom8030057] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 07/13/2018] [Accepted: 07/14/2018] [Indexed: 02/06/2023] Open
Abstract
The ubiquitous calcium transducer calmodulin (CaM) plays a pivotal role in many cellular processes, regulating a myriad of structurally different target proteins. Indeed, it is unquestionable that CaM is the most relevant transductor of calcium signals in eukaryotic cells. During the last two decades, different studies have demonstrated that CaM mediates the modulation of several ion channels. Among others, it has been indicated that Kv7.2 channels, one of the members of the voltage gated potassium channel family that plays a critical role in brain excitability, requires CaM binding to regulate the different mechanisms that govern its functions. The purpose of this review is to provide an overview of the most recent advances in structure–function studies on the role of CaM regulation of Kv7.2 and the other members of the Kv7 family.
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43
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Kim EC, Zhang J, Pang W, Wang S, Lee KY, Cavaretta JP, Walters J, Procko E, Tsai NP, Chung HJ. Reduced axonal surface expression and phosphoinositide sensitivity in K v7 channels disrupts their function to inhibit neuronal excitability in Kcnq2 epileptic encephalopathy. Neurobiol Dis 2018; 118:76-93. [PMID: 30008368 DOI: 10.1016/j.nbd.2018.07.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 06/22/2018] [Accepted: 07/04/2018] [Indexed: 01/08/2023] Open
Abstract
Neuronal Kv7/KCNQ channels are voltage-gated potassium channels composed of Kv7.2/KCNQ2 and Kv7.3/KCNQ3 subunits. Enriched at the axonal membrane, they potently suppress neuronal excitability. De novo and inherited dominant mutations in Kv7.2 cause early onset epileptic encephalopathy characterized by drug resistant seizures and profound psychomotor delay. However, their precise pathogenic mechanisms remain elusive. Here, we investigated selected epileptic encephalopathy causing mutations in calmodulin (CaM)-binding helices A and B of Kv7.2. We discovered that R333W, K526N, and R532W mutations located peripheral to CaM contact sites decreased axonal surface expression of heteromeric channels although only R333W mutation reduced CaM binding to Kv7.2. These mutations also altered gating modulation by phosphatidylinositol 4,5-bisphosphate (PIP2), revealing novel PIP2 binding residues. While these mutations disrupted Kv7 function to suppress excitability, hyperexcitability was observed in neurons expressing Kv7.2-R532W that displayed severe impairment in voltage-dependent activation. The M518 V mutation at the CaM contact site in helix B caused most defects in Kv7 channels by severely reducing their CaM binding, K+ currents, and axonal surface expression. Interestingly, the M518 V mutation induced ubiquitination and accelerated proteasome-dependent degradation of Kv7.2, whereas the presence of Kv7.3 blocked this degradation. Furthermore, expression of Kv7.2-M518V increased neuronal death. Together, our results demonstrate that epileptic encephalopathy mutations in helices A and B of Kv7.2 cause abnormal Kv7 expression and function by disrupting Kv7.2 binding to CaM and/or modulation by PIP2. We propose that such multiple Kv7 channel defects could exert more severe impacts on neuronal excitability and health, and thus serve as pathogenic mechanisms underlying Kcnq2 epileptic encephalopathy.
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Affiliation(s)
- Eung Chang Kim
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Jiaren Zhang
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Weilun Pang
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Shuwei Wang
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Kwan Young Lee
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - John P Cavaretta
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Jennifer Walters
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Erik Procko
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Nien-Pei Tsai
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Hee Jung Chung
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
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44
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Structural basis and energy landscape for the Ca 2+ gating and calmodulation of the Kv7.2 K + channel. Proc Natl Acad Sci U S A 2018; 115:2395-2400. [PMID: 29463698 PMCID: PMC5873240 DOI: 10.1073/pnas.1800235115] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Ion channels are sophisticated proteins that exert control over a plethora of body functions. Specifically, the members of the Kv7 family are prominent components of the nervous systems, responsible for the ion fluxes that regulate the electrical signaling in neurons and cardiac myocytes. Albeit its relevance, there are still several questions, including the Ca2+/calmodulin (CaM)-mediated gating mechanism. We found that Ca2+ binding to CaM triggers a segmental rotation that allosterically transmits the signal from the cytosol up to the transmembrane region. NMR-derived analysis of the dynamics demonstrates that it occurs through a conformational selection mechanism. Energetically, CaM association with the channel tunes the affinities of the CaM lobes (calmodulation) so that the channel can sense the specific changes in [Ca2+] resulting after an action potential. The Kv7.2 (KCNQ2) channel is the principal molecular component of the slow voltage-gated, noninactivating K+ M-current, a key controller of neuronal excitability. To investigate the calmodulin (CaM)-mediated Ca2+ gating of the channel, we used NMR spectroscopy to structurally and dynamically describe the association of helices hA and hB of Kv7.2 with CaM, as a function of Ca2+ concentration. The structures of the CaM/Kv7.2-hAB complex at two different calcification states are reported here. In the presence of a basal cytosolic Ca2+ concentration (10–100 nM), only the N-lobe of CaM is Ca2+-loaded and the complex (representative of the open channel) exhibits collective dynamics on the millisecond time scale toward a low-populated excited state (1.5%) that corresponds to the inactive state of the channel. In response to a chemical or electrical signal, intracellular Ca2+ levels rise up to 1–10 μM, triggering Ca2+ association with the C-lobe. The associated conformational rearrangement is the key biological signal that shifts populations to the closed/inactive channel. This reorientation affects the C-lobe of CaM and both helices in Kv7.2, allosterically transducing the information from the Ca2+-binding site to the transmembrane region of the channel.
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45
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Chang A, Abderemane-Ali F, Hura GL, Rossen ND, Gate RE, Minor DL. A Calmodulin C-Lobe Ca 2+-Dependent Switch Governs Kv7 Channel Function. Neuron 2018; 97:836-852.e6. [PMID: 29429937 DOI: 10.1016/j.neuron.2018.01.035] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 12/07/2017] [Accepted: 01/12/2018] [Indexed: 12/22/2022]
Abstract
Kv7 (KCNQ) voltage-gated potassium channels control excitability in the brain, heart, and ear. Calmodulin (CaM) is crucial for Kv7 function, but how this calcium sensor affects activity has remained unclear. Here, we present X-ray crystallographic analysis of CaM:Kv7.4 and CaM:Kv7.5 AB domain complexes that reveal an Apo/CaM clamp conformation and calcium binding preferences. These structures, combined with small-angle X-ray scattering, biochemical, and functional studies, establish a regulatory mechanism for Kv7 CaM modulation based on a common architecture in which a CaM C-lobe calcium-dependent switch releases a shared Apo/CaM clamp conformation. This C-lobe switch inhibits voltage-dependent activation of Kv7.4 and Kv7.5 but facilitates Kv7.1, demonstrating that mechanism is shared by Kv7 isoforms despite the different directions of CaM modulation. Our findings provide a unified framework for understanding how CaM controls different Kv7 isoforms and highlight the role of membrane proximal domains for controlling voltage-gated channel function. VIDEO ABSTRACT.
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Affiliation(s)
- Aram Chang
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA 94158, USA
| | - Fayal Abderemane-Ali
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA 94158, USA
| | - Greg L Hura
- Molecular Biophysics and Integrated Bio-imaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Nathan D Rossen
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA 94158, USA
| | - Rachel E Gate
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA 94158, USA
| | - Daniel L Minor
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA 94158, USA; Molecular Biophysics and Integrated Bio-imaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Departments of Biochemistry and Biophysics, and Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, CA 94158, USA; California Institute for Quantitative Biomedical Research, University of California San Francisco, San Francisco, CA 94158, USA; Kavli Institute for Fundamental Neuroscience, University of California San Francisco, San Francisco, CA 94158, USA.
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46
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Barrese V, Stott JB, Greenwood IA. KCNQ-Encoded Potassium Channels as Therapeutic Targets. Annu Rev Pharmacol Toxicol 2018; 58:625-648. [DOI: 10.1146/annurev-pharmtox-010617-052912] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
| | | | - Iain A. Greenwood
- Vascular Biology Research Centre, Molecular and Clinical Sciences Institute, St George's, University of London, London, SW17 0RE, United Kingdom;, ,
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47
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Tobelaim WS, Dvir M, Lebel G, Cui M, Buki T, Peretz A, Marom M, Haitin Y, Logothetis DE, Hirsch JA, Attali B. Ca 2+-Calmodulin and PIP2 interactions at the proximal C-terminus of Kv7 channels. Channels (Austin) 2017; 11:686-695. [PMID: 28976808 PMCID: PMC5786183 DOI: 10.1080/19336950.2017.1388478] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Revised: 09/18/2017] [Accepted: 09/29/2017] [Indexed: 10/18/2022] Open
Abstract
In the heart, co-assembly of Kv7.1 with KCNE1 produces the slow IKS potassium current, which repolarizes the cardiac action potential and mutations in human Kv7.1 and KCNE1 genes cause cardiac arrhythmias. The proximal Kv7.1 C-terminus binds calmodulin (CaM) and phosphatidylinositol-4,5-bisphosphate (PIP2) and recently we revealed the competition of PIP2 with the calcified CaM N-lobe to a previously unidentified site in Kv7.1 helix B, also known to harbor a LQT mutation. Data indicated that PIP2 and Ca2+-CaM perform the same function on IKS channel gating to stabilize the channel open state. Here we show that similar features were observed for Kv7.1 currents expressed alone. We also find that conservation of homologous residues in helix B of other Kv7 subtypes confer similar competition of Ca2+-CaM with PIP2 binding to their proximal C-termini and suggest that PIP2-CaM interactions converge to Kv7 helix B to modulates channel activity in a Kv7 subtype-dependent manner.
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Affiliation(s)
- William S. Tobelaim
- Department of Physiology & Pharmacology, Sackler Faculty of Medicine and Sagol School of Neurosciences, Tel Aviv University, Tel Aviv, Israel
| | - Meidan Dvir
- Department of Physiology & Pharmacology, Sackler Faculty of Medicine and Sagol School of Neurosciences, Tel Aviv University, Tel Aviv, Israel
| | - Guy Lebel
- Department of Biochemistry & Molecular Biology, George S. Wise Faculty of Life Sciences, Institute of Structural Biology, Tel Aviv University, Tel Aviv, Israel
| | - Meng Cui
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, USA
| | - Tal Buki
- Laboratory of Structural Physiology, Department of Physiology & Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Asher Peretz
- Department of Physiology & Pharmacology, Sackler Faculty of Medicine and Sagol School of Neurosciences, Tel Aviv University, Tel Aviv, Israel
| | - Milit Marom
- Laboratory of Structural Physiology, Department of Physiology & Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Yoni Haitin
- Laboratory of Structural Physiology, Department of Physiology & Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | | | - Joel A. Hirsch
- Department of Biochemistry & Molecular Biology, George S. Wise Faculty of Life Sciences, Institute of Structural Biology, Tel Aviv University, Tel Aviv, Israel
| | - Bernard Attali
- Department of Physiology & Pharmacology, Sackler Faculty of Medicine and Sagol School of Neurosciences, Tel Aviv University, Tel Aviv, Israel
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48
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Antúnez-Argüelles E, Rojo-Domínguez A, Arregui-Mena AL, Jacobo-Albavera L, Márquez MF, Iturralde-Torres P, Villarreal-Molina MT. Compound heterozygous KCNQ1 mutations (A300T/P535T) in a child with sudden unexplained death: Insights into possible molecular mechanisms based on protein modeling. Gene 2017; 627:40-48. [PMID: 28600177 DOI: 10.1016/j.gene.2017.06.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Revised: 05/18/2017] [Accepted: 06/05/2017] [Indexed: 11/26/2022]
Abstract
Sudden death in a child is a devastating event with important medical implications for surviving relatives. Because it may be the first manifestation of unknown inherited cardiac disease, molecular autopsy can be helpful to determine the cause of death and identify at risk family members. The aim of the study was to perform a molecular autopsy in a seven year-old girl with sudden unexplained death, to find evidence supporting the possible pathogenicity of mutations identified in inherited cardiac disease genes, and to clinically and genetically assess first-degree relatives. DNA from the index case was extracted from umbilical cord cells stored at birth, and DNA of first-degree relatives from blood samples. Targeted sequencing was performed using a Haloplex design including 81 cardiogenes. Possible functional consequences of the mutations were analyzed using protein modeling and structural mobility analyses. The child was compound heterozygous for KCNQ1 variants p.Ala300Thr and p.Pro535Thr. Ala300Thr is known to cause long QT syndrome in the homozygous state, while Pro535Thr is novel and of unknown clinical significance. The father and sibling were Ala300Thr heterozygous, and had normal QTc intervals at rest and during exercise. The asymptomatic mother was heterozygous for Pro535Thr, and showed borderline QTc at rest, but prolonged QTc during exercise. Protein modeling predicted that Ala300Thr alters the mobility profile of the Kv7.1 tetramer and Thr535 disrupts a calmodulin-binding site, probably causing co-assembly or trafficking defects of the mutant monomer. Altogether, the evidence strongly suggests that this child was affected with a recessive form of Romano Ward syndrome.
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Affiliation(s)
- Erika Antúnez-Argüelles
- Laboratorio de Genómica de Enfermedades Cardiovasculares, Instituto Nacional de Medicina Genómica, Mexico
| | - Arturo Rojo-Domínguez
- Departamento de Ciencias Naturales, Universidad Autónoma Metropolitana Unidad Cuajimalpa, Mexico
| | - Ana Leticia Arregui-Mena
- Departamento de Ciencias Naturales, Universidad Autónoma Metropolitana Unidad Cuajimalpa, Mexico
| | - Leonor Jacobo-Albavera
- Laboratorio de Genómica de Enfermedades Cardiovasculares, Instituto Nacional de Medicina Genómica, Mexico
| | - Manlio Fabio Márquez
- Departamento de Electrofisiología, Instituto Nacional de Cardiología "Ignacio Chávez", Mexico
| | - Pedro Iturralde-Torres
- Departamento de Electrofisiología, Instituto Nacional de Cardiología "Ignacio Chávez", Mexico
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49
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Tykocki NR, Boerman EM, Jackson WF. Smooth Muscle Ion Channels and Regulation of Vascular Tone in Resistance Arteries and Arterioles. Compr Physiol 2017; 7:485-581. [PMID: 28333380 DOI: 10.1002/cphy.c160011] [Citation(s) in RCA: 222] [Impact Index Per Article: 31.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Vascular tone of resistance arteries and arterioles determines peripheral vascular resistance, contributing to the regulation of blood pressure and blood flow to, and within the body's tissues and organs. Ion channels in the plasma membrane and endoplasmic reticulum of vascular smooth muscle cells (SMCs) in these blood vessels importantly contribute to the regulation of intracellular Ca2+ concentration, the primary determinant of SMC contractile activity and vascular tone. Ion channels provide the main source of activator Ca2+ that determines vascular tone, and strongly contribute to setting and regulating membrane potential, which, in turn, regulates the open-state-probability of voltage gated Ca2+ channels (VGCCs), the primary source of Ca2+ in resistance artery and arteriolar SMCs. Ion channel function is also modulated by vasoconstrictors and vasodilators, contributing to all aspects of the regulation of vascular tone. This review will focus on the physiology of VGCCs, voltage-gated K+ (KV) channels, large-conductance Ca2+-activated K+ (BKCa) channels, strong-inward-rectifier K+ (KIR) channels, ATP-sensitive K+ (KATP) channels, ryanodine receptors (RyRs), inositol 1,4,5-trisphosphate receptors (IP3Rs), and a variety of transient receptor potential (TRP) channels that contribute to pressure-induced myogenic tone in resistance arteries and arterioles, the modulation of the function of these ion channels by vasoconstrictors and vasodilators, their role in the functional regulation of tissue blood flow and their dysfunction in diseases such as hypertension, obesity, and diabetes. © 2017 American Physiological Society. Compr Physiol 7:485-581, 2017.
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Affiliation(s)
- Nathan R Tykocki
- Department of Pharmacology, University of Vermont, Burlington, Vermont, USA
| | - Erika M Boerman
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri, USA
| | - William F Jackson
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan, USA
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50
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Al Yazidi G, Shevell MI, Srour M. Two Novel KCNQ2 Mutations in 2 Families With Benign Familial Neonatal Convulsions. Child Neurol Open 2017; 4:2329048X17691396. [PMID: 28503627 PMCID: PMC5417349 DOI: 10.1177/2329048x17691396] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 11/10/2016] [Accepted: 11/22/2016] [Indexed: 11/16/2022] Open
Abstract
Benign familial neonatal convulsion is a rare autosomal dominant inherited epilepsy syndrome characterized by unprovoked seizures in the first few days of life, normal psychomotor development, and a positive intergenerational family history of neonatal seizures. Over 90% of the affected individuals have inherited causal mutations in KCNQ2, which encodes for the potassium voltage-gated channel subfamily Q, member 2. Mutations in KCNQ2 are also associated with a severe neonatal encephalopathy phenotype associated with poor seizure control and neurodevelopmental deficits. The authors report the clinical presentations, response to medication, and intrafamilial phenotypic variability in 2 families with benign familial neonatal convulsions, carrying previously unreported heterozygous missense mutations, c.1066C>G (p.Leu356Val) and c.1721G<A (p.Gly574Asp), in KCNQ2. The cases reported herein suggest that inherited missense mutations in KCNQ2 can be associated with an intermediate phenotype and illustrate the challenges associated with prognosis and counselling for individuals with inherited missense mutations in KCNQ2.
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Affiliation(s)
- Ghalia Al Yazidi
- Division of Pediatric Neurology, Montreal Children's Hospital, McGill University Health Centre (MUHC), Montréal, Quebec City, Canada.,Departments of Pediatrics, Neurology and Neurosurgery, McGill University, Montreal, Quebec City, Canada
| | - Michael I Shevell
- Division of Pediatric Neurology, Montreal Children's Hospital, McGill University Health Centre (MUHC), Montréal, Quebec City, Canada.,Departments of Pediatrics, Neurology and Neurosurgery, McGill University, Montreal, Quebec City, Canada
| | - Myriam Srour
- Division of Pediatric Neurology, Montreal Children's Hospital, McGill University Health Centre (MUHC), Montréal, Quebec City, Canada.,Departments of Pediatrics, Neurology and Neurosurgery, McGill University, Montreal, Quebec City, Canada
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