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Martina M, Banderali U, Yogi A, Arbabi Ghahroudi M, Liu H, Sulea T, Durocher Y, Hussack G, van Faassen H, Chakravarty B, Liu QY, Iqbal U, Ling B, Lessard E, Sheff J, Robotham A, Callaghan D, Moreno M, Comas T, Ly D, Stanimirovic D. A Novel Antigen Design Strategy to Isolate Single-Domain Antibodies that Target Human Nav1.7 and Reduce Pain in Animal Models. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024:e2405432. [PMID: 39206821 DOI: 10.1002/advs.202405432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2024] [Revised: 08/01/2024] [Indexed: 09/04/2024]
Abstract
Genetic studies have identified the voltage-gated sodium channel 1.7 (Nav1.7) as pain target. Due to the ineffectiveness of small molecules and monoclonal antibodies as therapeutics for pain, single-domain antibodies (VHHs) are developed against the human Nav1.7 (hNav1.7) using a novel antigen presentation strategy. A 70 amino-acid peptide from the hNav1.7 protein is identified as a target antigen. A recombinant version of this peptide is grafted into the complementarity determining region 3 (CDR3) loop of an inert VHH in order to maintain the native 3D conformation of the peptide. This antigen is used to isolate one VHH able to i) bind hNav1.7, ii) slow the deactivation of hNav1.7, iii) reduce the ability of eliciting action potentials in nociceptors, and iv) reverse hyperalgesia in in vivo rat and mouse models. This VHH exhibits the potential to be developed as a therapeutic capable of suppressing pain. This novel antigen presentation strategy can be applied to develop biologics against other difficult targets such as ion channels, transporters and GPCRs.
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Affiliation(s)
- Marzia Martina
- Human Health Therapeutics Research Center, National Research Council Canada, 1200 Montreal Road, Building M54, Ottawa, ON, K1A 0R6, Canada
| | - Umberto Banderali
- Human Health Therapeutics Research Center, National Research Council Canada, 1200 Montreal Road, Building M54, Ottawa, ON, K1A 0R6, Canada
| | - Alvaro Yogi
- Human Health Therapeutics Research Center, National Research Council Canada, 1200 Montreal Road, Building M54, Ottawa, ON, K1A 0R6, Canada
| | - Mehdi Arbabi Ghahroudi
- Human Health Therapeutics Research Centre, National Research Council Canada, 100 Sussex Drive, Ottawa, ON, K1N 5A2, Canada
| | - Hong Liu
- Human Health Therapeutics Research Center, National Research Council Canada, 1200 Montreal Road, Building M54, Ottawa, ON, K1A 0R6, Canada
| | - Traian Sulea
- Human Health Therapeutics Research Centre, National Research Council Canada, 6100 Royalmount Avenue Montréal, Quebec, H4P 2R2, Canada
| | - Yves Durocher
- Human Health Therapeutics Research Centre, National Research Council Canada, 6100 Royalmount Avenue Montréal, Quebec, H4P 2R2, Canada
| | - Greg Hussack
- Human Health Therapeutics Research Centre, National Research Council Canada, 100 Sussex Drive, Ottawa, ON, K1N 5A2, Canada
| | - Henk van Faassen
- Human Health Therapeutics Research Centre, National Research Council Canada, 100 Sussex Drive, Ottawa, ON, K1N 5A2, Canada
| | - Balu Chakravarty
- Human Health Therapeutics Research Center, National Research Council Canada, 1200 Montreal Road, Building M54, Ottawa, ON, K1A 0R6, Canada
| | - Qing Yan Liu
- Human Health Therapeutics Research Center, National Research Council Canada, 1200 Montreal Road, Building M54, Ottawa, ON, K1A 0R6, Canada
| | - Umar Iqbal
- Human Health Therapeutics Research Center, National Research Council Canada, 1200 Montreal Road, Building M54, Ottawa, ON, K1A 0R6, Canada
| | - Binbing Ling
- Human Health Therapeutics Research Center, National Research Council Canada, 1200 Montreal Road, Building M54, Ottawa, ON, K1A 0R6, Canada
| | - Etienne Lessard
- Human Health Therapeutics Research Centre, National Research Council Canada, 6100 Royalmount Avenue Montréal, Quebec, H4P 2R2, Canada
| | - Joey Sheff
- Human Health Therapeutics Research Centre, National Research Council Canada, 100 Sussex Drive, Ottawa, ON, K1N 5A2, Canada
| | - Anna Robotham
- Human Health Therapeutics Research Centre, National Research Council Canada, 100 Sussex Drive, Ottawa, ON, K1N 5A2, Canada
| | - Debbie Callaghan
- Human Health Therapeutics Research Centre, National Research Council Canada, 100 Sussex Drive, Ottawa, ON, K1N 5A2, Canada
| | - Maria Moreno
- Human Health Therapeutics Research Center, National Research Council Canada, 1200 Montreal Road, Building M54, Ottawa, ON, K1A 0R6, Canada
| | - Tanya Comas
- Human Health Therapeutics Research Center, National Research Council Canada, 1200 Montreal Road, Building M54, Ottawa, ON, K1A 0R6, Canada
| | - Dao Ly
- Human Health Therapeutics Research Center, National Research Council Canada, 1200 Montreal Road, Building M54, Ottawa, ON, K1A 0R6, Canada
| | - Danica Stanimirovic
- Human Health Therapeutics Research Center, National Research Council Canada, 1200 Montreal Road, Building M54, Ottawa, ON, K1A 0R6, Canada
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2
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Catterall WA, Gamal El-Din TM, Wisedchaisri G. The chemistry of electrical signaling in sodium channels from bacteria and beyond. Cell Chem Biol 2024; 31:1405-1421. [PMID: 39151407 DOI: 10.1016/j.chembiol.2024.07.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Revised: 06/27/2024] [Accepted: 07/22/2024] [Indexed: 08/19/2024]
Abstract
Electrical signaling is essential for all fast processes in biology, but its molecular mechanisms have been uncertain. This review article focuses on studies of bacterial sodium channels in order to home in on the essential molecular and chemical mechanisms underlying transmembrane ion conductance and voltage-dependent gating without the overlay of complex protein interactions and regulatory mechanisms in mammalian sodium channels. This minimalist approach has yielded a nearly complete picture of sodium channel function at the atomic level that are mostly conserved in mammalian sodium channels, including sodium selectivity and conductance, voltage sensing and activation, electromechanical coupling to pore opening and closing, slow inactivation, and pathogenic dysfunction in a debilitating channelopathy. Future studies of nature's simplest sodium channels may continue to yield key insights into the fundamental molecular and chemical principles of their function and further elucidate the chemical basis of electrical signaling.
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Affiliation(s)
- William A Catterall
- Department of Pharmacology, University of Washington, Seattle WA 98195-7280, USA.
| | - Tamer M Gamal El-Din
- Department of Pharmacology, University of Washington, Seattle WA 98195-7280, USA.
| | - Goragot Wisedchaisri
- Department of Pharmacology, University of Washington, Seattle WA 98195-7280, USA.
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3
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Li M, Jin Y, Wu J, Zhao M, Yu K, Yu H. Arbidol, an antiviral drug, identified as a sodium channel blocker with anticonvulsant activity. Br J Pharmacol 2024. [PMID: 38982721 DOI: 10.1111/bph.16496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 05/24/2024] [Accepted: 05/30/2024] [Indexed: 07/11/2024] Open
Abstract
BACKGROUND AND PURPOSE Sodium channel blockers (SCBs) have traditionally been utilized as anti-seizure medications by primarily targeting the inactivation process. In a drug discovery project aiming at finding potential anticonvulsants, we have identified arbidol, originally an antiviral drug, as a potent SCB. In order to evaluate its anticonvulsant potential, we have thoroughly examined its biophysical properties as well as its effects on animal seizure models. EXPERIMENTAL APPROACH Patch clamp recording was used to investigate the electrophysiological properties of arbidol, as well as the binding and unbinding kinetics of arbidol, carbamazepine and lacosamide. Furthermore, we evaluated the anticonvulsant effects of arbidol using three different seizure models in male mice. KEY RESULTS Arbidol effectively suppressed neuronal epileptiform activity by blocking sodium channels. Arbidol demonstrated a distinct mode of action by interacting with both the fast and slow inactivation of Nav1.2 channels compared with carbamazepine and lacosamide. A kinetic study suggested that the binding and unbinding rates might be associated with the specific characteristics of these three drugs. Arbidol targeted the classical binding site of local anaesthetics, effectively inhibited the gain-of-function effects of Nav1.2 epileptic mutations and exhibited varying degrees of anticonvulsant effects in the maximal electroshock model and subcutaneous pentylenetetrazol model but had no effect in the pilocarpine-induced status epilepticus model. CONCLUSIONS AND IMPLICATIONS Arbidol shows promising potential as an anticonvulsant agent, providing a unique mode of action that sets it apart from existing SCBs.
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Affiliation(s)
- Min Li
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, P. R. China
| | - Yuchen Jin
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, P. R. China
| | - Jun Wu
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, P. R. China
| | - Miao Zhao
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, P. R. China
| | - Kexin Yu
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, P. R. China
| | - Haibo Yu
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, P. R. China
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4
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Moreira-Junior L, Leal-Cardoso JH, Cassola AC, Carvalho-de-Souza JL. Eugenol and lidocaine inhibit voltage-gated Na + channels from dorsal root ganglion neurons with different mechanisms. Front Pharmacol 2024; 15:1354737. [PMID: 38989141 PMCID: PMC11234063 DOI: 10.3389/fphar.2024.1354737] [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: 12/12/2023] [Accepted: 04/08/2024] [Indexed: 07/12/2024] Open
Abstract
Eugenol (EUG) is a bioactive monoterpenoid used as an analgesic, preservative, and flavoring agent. Our new data show EUG as a voltage-gated Na+ channel (VGSC) inhibitor, comparable but not identical to lidocaine (LID). EUG inhibits both total and only TTX-R voltage-activated Na+ currents (INa) recorded from VGSCs naturally expressed on dorsal root ganglion sensory neurons in rats. Inhibition is quick, fully reversible, and dose-dependent. Our biophysical and pharmacological analyses showed that EUG and LID inhibit VGSCs with different mechanisms. EUG inhibits VGSCs with a dose-response relationship characterized by a Hill coefficient of 2, while this parameter for the inhibition by LID is 1. Furthermore, in a different way from LID, EUG modified the voltage dependence of both the VGSC activation and inactivation processes and the recovery from fast inactivated states and the entry to slow inactivated states. In addition, we suggest that EUG, but not LID, interacts with VGSC pre-open-closed states, according to our data.
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Affiliation(s)
- Luiz Moreira-Junior
- Department of Anesthesiology, University of Arizona, Tucson, AZ, United States
| | | | - Antonio Carlos Cassola
- Department of Physiology and Biophysics, Biomedical Sciences Institute, University of Sao Paulo, São Paulo, Brazil
| | - Joao Luis Carvalho-de-Souza
- Department of Anesthesiology, University of Arizona, Tucson, AZ, United States
- Department of Physiology and Biophysics, Biomedical Sciences Institute, University of Sao Paulo, São Paulo, Brazil
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5
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Chen H, Xia Z, Dong J, Huang B, Zhang J, Zhou F, Yan R, Shi Y, Gong J, Jiang J, Huang Z, Jiang D. Structural mechanism of voltage-gated sodium channel slow inactivation. Nat Commun 2024; 15:3691. [PMID: 38693179 PMCID: PMC11063143 DOI: 10.1038/s41467-024-48125-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Accepted: 04/17/2024] [Indexed: 05/03/2024] Open
Abstract
Voltage-gated sodium (NaV) channels mediate a plethora of electrical activities. NaV channels govern cellular excitability in response to depolarizing stimuli. Inactivation is an intrinsic property of NaV channels that regulates cellular excitability by controlling the channel availability. The fast inactivation, mediated by the Ile-Phe-Met (IFM) motif and the N-terminal helix (N-helix), has been well-characterized. However, the molecular mechanism underlying NaV channel slow inactivation remains elusive. Here, we demonstrate that the removal of the N-helix of NaVEh (NaVEhΔN) results in a slow-inactivated channel, and present cryo-EM structure of NaVEhΔN in a potential slow-inactivated state. The structure features a closed activation gate and a dilated selectivity filter (SF), indicating that the upper SF and the inner gate could serve as a gate for slow inactivation. In comparison to the NaVEh structure, NaVEhΔN undergoes marked conformational shifts on the intracellular side. Together, our results provide important mechanistic insights into NaV channel slow inactivation.
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Affiliation(s)
- Huiwen Chen
- Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, No. 600 Changjiang Road, Xiangfang District, Harbin, 150030, China
- Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Zhanyi Xia
- Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Jie Dong
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Bo Huang
- Beijing StoneWise Technology Co Ltd., 15 Haidian street, Haidian district, Beijing, China
| | - Jiangtao Zhang
- Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- College of Life Science and Technology, Key Laboratory of Molecular Biophysics of MOE, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Feng Zhou
- Beijing StoneWise Technology Co Ltd., 15 Haidian street, Haidian district, Beijing, China
| | - Rui Yan
- Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- College of Life Science and Technology, Key Laboratory of Molecular Biophysics of MOE, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Yiqiang Shi
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Jianke Gong
- College of Life Science and Technology, Key Laboratory of Molecular Biophysics of MOE, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Juquan Jiang
- Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, No. 600 Changjiang Road, Xiangfang District, Harbin, 150030, China.
| | - Zhuo Huang
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing, 100191, China.
| | - Daohua Jiang
- Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100190, China.
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6
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Eltokhi A, Lundstrom BN, Li J, Zweifel LS, Catterall WA, Gamal El-Din TM. Pathogenic gating pore current conducted by autism-related mutations in the Na V1.2 brain sodium channel. Proc Natl Acad Sci U S A 2024; 121:e2317769121. [PMID: 38564633 PMCID: PMC11009634 DOI: 10.1073/pnas.2317769121] [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: 10/23/2023] [Accepted: 02/26/2024] [Indexed: 04/04/2024] Open
Abstract
Autism spectrum disorder (ASD) is a complex neurodevelopmental condition characterized by social and communication deficits and repetitive behaviors. The genetic heterogeneity of ASD presents a challenge to the development of an effective treatment targeting the underlying molecular defects. ASD gating charge mutations in the KCNQ/KV7 potassium channel cause gating pore currents (Igp) and impair action potential (AP) firing of dopaminergic neurons in brain slices. Here, we investigated ASD gating charge mutations of the voltage-gated SCN2A/NaV1.2 brain sodium channel, which ranked high among the ion channel genes with mutations in individuals with ASD. Our results show that ASD mutations in the gating charges R2 in Domain-II (R853Q), and R1 (R1626Q) and R2 (R1629H) in Domain-IV of NaV1.2 caused Igp in the resting state of ~0.1% of the amplitude of central pore current. The R1626Q mutant also caused significant changes in the voltage dependence of fast inactivation, and the R1629H mutant conducted proton-selective Igp. These potentially pathogenic Igp were exacerbated by the absence of the extracellular Mg2+ and Ca2+. In silico simulation of the effects of these mutations in a conductance-based single-compartment cortical neuron model suggests that the inward Igp reduces the time to peak for the first AP in a train, increases AP rates during a train of stimuli, and reduces the interstimulus interval between consecutive APs, consistent with increased neural excitability and altered input/output relationships. Understanding this common pathophysiological mechanism among different voltage-gated ion channels at the circuit level will give insights into the underlying mechanisms of ASD.
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Affiliation(s)
- Ahmed Eltokhi
- Department of Pharmacology, University of Washington, Seattle, WA98195
| | - Brian Nils Lundstrom
- Department of Neurology in the Division of Epilepsy, Mayo Clinic, Rochester, MN55905
| | - Jin Li
- Department of Pharmacology, University of Washington, Seattle, WA98195
| | - Larry S. Zweifel
- Department of Pharmacology, University of Washington, Seattle, WA98195
- Department of Psychiatry & Behavioral Sciences, University of Washington, Seattle, WA98195
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7
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Li Y, Liu S, Huang J, Xie Y, Hou A, Wei Y. Cellular-level analyses of SCN5A mutations in left ventricular noncompaction cardiomyopathy suggest electrophysiological mechanisms for ventricular tachycardia. Biochem Biophys Rep 2024; 37:101653. [PMID: 38352122 PMCID: PMC10861951 DOI: 10.1016/j.bbrep.2024.101653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2023] [Revised: 01/22/2024] [Accepted: 01/24/2024] [Indexed: 02/16/2024] Open
Abstract
Left ventricular noncompaction cardiomyopathy (LVNC) is a cardiovascular disease characterized by arrhythmia and heart failure. In this study, LVNC myocardial samples were collected from patients who underwent heart transplantation and were analyzed using exome sequencing. Approximately half of the LVNC patients carried SCN5A variants, which are associated with clinical symptoms of ventricular tachycardia. To investigate the electrophysiological functions of these SCN5A variants and the underlying mechanism by which they increase arrhythmia susceptibility in LVNC patients, functional evaluations were conducted in CHO-K1 cells and human embryonic stem cell-derived cardiomyocytes (hESC-CMs) using patch-clamp or microelectrode array (MEA) techniques. These findings demonstrated that these SCN5A mutants exhibited gain-of-function properties, leading to increased channel activation and enhanced fast inactivation in CHO-K1 cells. Additionally, these mutants enhanced the excitability and contractility of the cardiomyocyte population in hESC-CMs models. All SCN5A variants induced fibrillation-like arrhythmia and increased the heart rate in cardiomyocytes. However, the administration of Lidocaine, an antiarrhythmic drug that acts on sodium ion channels, was able to rescue or alleviate fibrillation-like arrhythmias and secondary beat phenomenon. Based on these findings, it is speculated that SCN5A variants may contribute to susceptibility to arrhythmia in LVNC patients. Furthermore, the construction of cardiomyocyte models with SCN5A variants and their application in drug screening may facilitate the development of precise therapies for arrhythmia in the future.
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Affiliation(s)
- Yanfen Li
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100037, People's Republic of China
| | - Shenghua Liu
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100037, People's Republic of China
| | - Jian Huang
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100037, People's Republic of China
| | - Yuanyuan Xie
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100037, People's Republic of China
| | - Aijie Hou
- Department of Cardiology, The People's Hospital of China Medical University, The People's Hospital of Liaoning Province, No. 33, Wenyi Road, Shenhe District, Shenyang City, Liaoning Province, 110016, People's Republic of China
| | - Yingjie Wei
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100037, People's Republic of China
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8
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Catterall WA. Voltage gated sodium and calcium channels: Discovery, structure, function, and Pharmacology. Channels (Austin) 2023; 17:2281714. [PMID: 37983307 PMCID: PMC10761118 DOI: 10.1080/19336950.2023.2281714] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Accepted: 10/11/2023] [Indexed: 11/22/2023] Open
Abstract
Voltage-gated sodium channels initiate action potentials in nerve and muscle, and voltage-gated calcium channels couple depolarization of the plasma membrane to intracellular events such as secretion, contraction, synaptic transmission, and gene expression. In this Review and Perspective article, I summarize early work that led to identification, purification, functional reconstitution, and determination of the amino acid sequence of the protein subunits of sodium and calcium channels and showed that their pore-forming subunits are closely related. Decades of study by antibody mapping, site-directed mutagenesis, and electrophysiological recording led to detailed two-dimensional structure-function maps of the amino acid residues involved in voltage-dependent activation and inactivation, ion permeation and selectivity, and pharmacological modulation. Most recently, high-resolution three-dimensional structure determination by X-ray crystallography and cryogenic electron microscopy has revealed the structural basis for sodium and calcium channel function and pharmacological modulation at the atomic level. These studies now define the chemical basis for electrical signaling and provide templates for future development of new therapeutic agents for a range of neurological and cardiovascular diseases.
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9
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Ulyanova AV, Adam CD, Cottone C, Maheshwari N, Grovola MR, Fruchet OE, Alamar J, Koch PF, Johnson VE, Cullen DK, Wolf JA. Hippocampal interneuronal dysfunction and hyperexcitability in a porcine model of concussion. Commun Biol 2023; 6:1136. [PMID: 37945934 PMCID: PMC10636018 DOI: 10.1038/s42003-023-05491-w] [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: 03/18/2022] [Accepted: 10/19/2023] [Indexed: 11/12/2023] Open
Abstract
Cognitive impairment is a common symptom following mild traumatic brain injury (mTBI or concussion) and can persist for years in some individuals. Hippocampal slice preparations following closed-head, rotational acceleration injury in swine have previously demonstrated reduced axonal function and hippocampal circuitry disruption. However, electrophysiological changes in hippocampal neurons and their subtypes in a large animal mTBI model have not been examined. Using in vivo electrophysiology techniques, we examined laminar oscillatory field potentials and single unit activity in the hippocampal network 7 days post-injury in anesthetized minipigs. Concussion altered the electrophysiological properties of pyramidal cells and interneurons differently in area CA1. While the firing rate, spike width and amplitude of CA1 interneurons were significantly decreased post-mTBI, these parameters were unchanged in CA1 pyramidal neurons. In addition, CA1 pyramidal neurons in TBI animals were less entrained to hippocampal gamma (40-80 Hz) oscillations. Stimulation of the Schaffer collaterals also revealed hyperexcitability across the CA1 lamina post-mTBI. Computational simulations suggest that reported changes in interneuronal physiology may be due to alterations in voltage-gated sodium channels. These data demonstrate that a single concussion can lead to significant neuronal and circuit level changes in the hippocampus, which may contribute to cognitive dysfunction following mTBI.
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Affiliation(s)
- Alexandra V Ulyanova
- Center for Brain Injury and Repair, Department of Neurosurgery, University of Pennsylvania, Philadelphia, USA
- Center for Neurotrauma, Neurodegeneration, and Restoration, Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, USA
| | - Christopher D Adam
- Center for Brain Injury and Repair, Department of Neurosurgery, University of Pennsylvania, Philadelphia, USA
| | - Carlo Cottone
- Center for Brain Injury and Repair, Department of Neurosurgery, University of Pennsylvania, Philadelphia, USA
| | - Nikhil Maheshwari
- Center for Brain Injury and Repair, Department of Neurosurgery, University of Pennsylvania, Philadelphia, USA
| | - Michael R Grovola
- Center for Brain Injury and Repair, Department of Neurosurgery, University of Pennsylvania, Philadelphia, USA
| | - Oceane E Fruchet
- Center for Brain Injury and Repair, Department of Neurosurgery, University of Pennsylvania, Philadelphia, USA
| | - Jami Alamar
- Center for Brain Injury and Repair, Department of Neurosurgery, University of Pennsylvania, Philadelphia, USA
| | - Paul F Koch
- Center for Brain Injury and Repair, Department of Neurosurgery, University of Pennsylvania, Philadelphia, USA
| | - Victoria E Johnson
- Center for Brain Injury and Repair, Department of Neurosurgery, University of Pennsylvania, Philadelphia, USA
| | - D Kacy Cullen
- Center for Brain Injury and Repair, Department of Neurosurgery, University of Pennsylvania, Philadelphia, USA
- Center for Neurotrauma, Neurodegeneration, and Restoration, Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, USA
| | - John A Wolf
- Center for Brain Injury and Repair, Department of Neurosurgery, University of Pennsylvania, Philadelphia, USA.
- Center for Neurotrauma, Neurodegeneration, and Restoration, Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, USA.
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10
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Marom S, Marder E. A biophysical perspective on the resilience of neuronal excitability across timescales. Nat Rev Neurosci 2023; 24:640-652. [PMID: 37620600 DOI: 10.1038/s41583-023-00730-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/27/2023] [Indexed: 08/26/2023]
Abstract
Neuronal membrane excitability must be resilient to perturbations that can take place over timescales from milliseconds to months (or even years in long-lived animals). A great deal of attention has been paid to classes of homeostatic mechanisms that contribute to long-term maintenance of neuronal excitability through processes that alter a key structural parameter: the number of ion channel proteins present at the neuronal membrane. However, less attention has been paid to the self-regulating 'automatic' mechanisms that contribute to neuronal resilience by virtue of the kinetic properties of ion channels themselves. Here, we propose that these two sets of mechanisms are complementary instantiations of feedback control, together enabling resilience on a wide range of temporal scales. We further point to several methodological and conceptual challenges entailed in studying these processes - both of which involve enmeshed feedback control loops - and consider the consequences of these mechanisms of resilience.
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Affiliation(s)
- Shimon Marom
- Faculty of Medicine, Technion - Institute of Technology, Haifa, Israel.
| | - Eve Marder
- Biology Department, Brandeis University, Waltham, MA, USA.
- Volen National Center for Complex Systems, Brandeis University, Waltham, MA, USA.
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11
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Zang Y, Marder E, Marom S. Sodium channel slow inactivation normalizes firing in axons with uneven conductance distributions. Curr Biol 2023; 33:1818-1824.e3. [PMID: 37023754 PMCID: PMC10175232 DOI: 10.1016/j.cub.2023.03.043] [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: 12/27/2022] [Revised: 02/17/2023] [Accepted: 03/15/2023] [Indexed: 04/08/2023]
Abstract
The Na+ channels that are important for action potentials show rapid inactivation, a state in which they do not conduct, although the membrane potential remains depolarized.1,2 Rapid inactivation is a determinant of millisecond-scale phenomena, such as spike shape and refractory period. Na+ channels also inactivate orders of magnitude more slowly, and this slow inactivation has impacts on excitability over much longer timescales than those of a single spike or a single inter-spike interval.3,4,5,6,7,8,9,10 Here, we focus on the contribution of slow inactivation to the resilience of axonal excitability11,12 when ion channels are unevenly distributed along the axon. We study models in which the voltage-gated Na+ and K+ channels are unevenly distributed along axons with different variances, capturing the heterogeneity that biological axons display.13,14 In the absence of slow inactivation, many conductance distributions result in spontaneous tonic activity. Faithful axonal propagation is achieved with the introduction of Na+ channel slow inactivation. This "normalization" effect depends on relations between the kinetics of slow inactivation and the firing frequency. Consequently, neurons with characteristically different firing frequencies will need to implement different sets of channel properties to achieve resilience. The results of this study demonstrate the importance of the intrinsic biophysical properties of ion channels in normalizing axonal function.
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Affiliation(s)
- Yunliang Zang
- Volen Center and Biology Department, Brandeis University, Waltham, MA 02454, USA.
| | - Eve Marder
- Volen Center and Biology Department, Brandeis University, Waltham, MA 02454, USA
| | - Shimon Marom
- Technion - Israel Institute of Technology, Haifa 32000, Israel
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12
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Wisedchaisri G, Gamal El-Din TM, Zheng N, Catterall WA. Structural basis for severe pain caused by mutations in the S4-S5 linkers of voltage-gated sodium channel Na V1.7. Proc Natl Acad Sci U S A 2023; 120:e2219624120. [PMID: 36996107 PMCID: PMC10083536 DOI: 10.1073/pnas.2219624120] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Accepted: 02/24/2023] [Indexed: 03/31/2023] Open
Abstract
Gain-of-function mutations in voltage-gated sodium channel NaV1.7 cause severe inherited pain syndromes, including inherited erythromelalgia (IEM). The structural basis of these disease mutations, however, remains elusive. Here, we focused on three mutations that all substitute threonine residues in the alpha-helical S4-S5 intracellular linker that connects the voltage sensor to the pore: NaV1.7/I234T, NaV1.7/I848T, and NaV1.7/S241T in order of their positions in the amino acid sequence within the S4-S5 linkers. Introduction of these IEM mutations into the ancestral bacterial sodium channel NaVAb recapitulated the pathogenic gain-of-function of these mutants by inducing a negative shift in the voltage dependence of activation and slowing the kinetics of inactivation. Remarkably, our structural analysis reveals a common mechanism of action among the three mutations, in which the mutant threonine residues create new hydrogen bonds between the S4-S5 linker and the pore-lining S5 or S6 segment in the pore module. Because the S4-S5 linkers couple voltage sensor movements to pore opening, these newly formed hydrogen bonds would stabilize the activated state substantially and thereby promote the 8 to 18 mV negative shift in the voltage dependence of activation that is characteristic of the NaV1.7 IEM mutants. Our results provide key structural insights into how IEM mutations in the S4-S5 linkers may cause hyperexcitability of NaV1.7 and lead to severe pain in this debilitating disease.
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Affiliation(s)
| | | | - Ning Zheng
- Department of Pharmacology, University of Washington, Seattle, WA98195
- HHMI, University of Washington, Seattle, WA98195
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13
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Woodward E, Rangel-Barajas C, Ringland A, Logrip ML, Coutellier L. Sex-Specific Timelines for Adaptations of Prefrontal Parvalbumin Neurons in Response to Stress and Changes in Anxiety- and Depressive-Like Behaviors. eNeuro 2023; 10:ENEURO.0300-22.2023. [PMID: 36808099 PMCID: PMC9997696 DOI: 10.1523/eneuro.0300-22.2023] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Revised: 01/12/2023] [Accepted: 01/18/2023] [Indexed: 02/22/2023] Open
Abstract
Women are twice as likely as men to experience emotional dysregulation after stress, resulting in substantially higher psychopathology for equivalent lifetime stress exposure, yet the mechanisms underlying this vulnerability remain unknown. Studies suggest changes in medial prefrontal cortex (mPFC) activity as a potential contributor. Whether maladaptive changes in inhibitory interneurons participate in this process, and whether adaptations in response to stress differ between men and women, producing sex-specific changes in emotional behaviors and mPFC activity, remained undetermined. This study examined whether unpredictable chronic mild stress (UCMS) in mice differentially alters behavior and mPFC parvalbumin (PV) interneuron activity by sex, and whether the activity of these neurons drives sex-specific behavioral changes. Four weeks of UCMS increased anxiety-like and depressive-like behaviors associated with FosB activation in mPFC PV neurons, particularly in females. After 8 weeks of UCMS, both sexes displayed these behavioral and neural changes. Chemogenetic activation of PV neurons in UCMS-exposed and nonstressed males induced significant changes in anxiety-like behaviors. Importantly, patch-clamp electrophysiology demonstrated altered excitability and basic neural properties on the same timeline as the emergence of behavioral effects: changes in females after 4 weeks and in males after 8 weeks of UCMS. These findings show, for the first time, that sex-specific changes in the excitability of prefrontal PV neurons parallel the emergence of anxiety-like behavior, revealing a potential novel mechanism underlying the enhanced vulnerability of females to stress-induced psychopathology and supporting further investigation of this neuronal population to identify new therapeutic targets for stress disorders.
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Affiliation(s)
- Emma Woodward
- Department of Neuroscience, The Ohio State University, Columbus, Ohio 43210
| | - Claudia Rangel-Barajas
- Department of Psychology, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana 46202
| | - Amanda Ringland
- Department of Psychology, The Ohio State University, Columbus, Ohio 43210
| | - Marian L Logrip
- Department of Psychology, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana 46202
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Laurence Coutellier
- Department of Neuroscience, The Ohio State University, Columbus, Ohio 43210
- Department of Psychology, The Ohio State University, Columbus, Ohio 43210
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14
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Ghovanloo MR, Tyagi S, Zhao P, Kiziltug E, Estacion M, Dib-Hajj SD, Waxman SG. High-throughput combined voltage-clamp/current-clamp analysis of freshly isolated neurons. CELL REPORTS METHODS 2023; 3:100385. [PMID: 36814833 PMCID: PMC9939380 DOI: 10.1016/j.crmeth.2022.100385] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 11/11/2022] [Accepted: 12/15/2022] [Indexed: 01/15/2023]
Abstract
The patch-clamp technique is the gold-standard methodology for analysis of excitable cells. However, throughput of manual patch-clamp is slow, and high-throughput robotic patch-clamp, while helpful for applications like drug screening, has been primarily used to study channels and receptors expressed in heterologous systems. We introduce an approach for automated high-throughput patch-clamping that enhances analysis of excitable cells at the channel and cellular levels. This involves dissociating and isolating neurons from intact tissues and patch-clamping using a robotic instrument, followed by using an open-source Python script for analysis and filtration. As a proof of concept, we apply this approach to investigate the biophysical properties of voltage-gated sodium (Nav) channels in dorsal root ganglion (DRG) neurons, which are among the most diverse and complex neuronal cells. Our approach enables voltage- and current-clamp recordings in the same cell, allowing unbiased, fast, simultaneous, and head-to-head electrophysiological recordings from a wide range of freshly isolated neurons without requiring culturing on coverslips.
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Affiliation(s)
- Mohammad-Reza Ghovanloo
- Department of Neurology, Yale University School of Medicine, New Haven, CT, USA
- Center for Neuroscience & Regeneration Research, Yale University, West Haven, CT, USA
- Neuro-Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, CT, USA
| | - Sidharth Tyagi
- Department of Neurology, Yale University School of Medicine, New Haven, CT, USA
- Center for Neuroscience & Regeneration Research, Yale University, West Haven, CT, USA
- Neuro-Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, CT, USA
- Medical Scientist Training Program, Yale University School of Medicine, New Haven, CT, USA
| | - Peng Zhao
- Department of Neurology, Yale University School of Medicine, New Haven, CT, USA
- Center for Neuroscience & Regeneration Research, Yale University, West Haven, CT, USA
- Neuro-Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, CT, USA
| | - Emre Kiziltug
- Department of Neurology, Yale University School of Medicine, New Haven, CT, USA
| | - Mark Estacion
- Department of Neurology, Yale University School of Medicine, New Haven, CT, USA
- Center for Neuroscience & Regeneration Research, Yale University, West Haven, CT, USA
- Neuro-Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, CT, USA
| | - Sulayman D. Dib-Hajj
- Department of Neurology, Yale University School of Medicine, New Haven, CT, USA
- Center for Neuroscience & Regeneration Research, Yale University, West Haven, CT, USA
- Neuro-Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, CT, USA
| | - Stephen G. Waxman
- Department of Neurology, Yale University School of Medicine, New Haven, CT, USA
- Center for Neuroscience & Regeneration Research, Yale University, West Haven, CT, USA
- Neuro-Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, CT, USA
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15
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Ghovanloo MR, Dib-Hajj SD, Goodchild SJ, Ruben PC, Waxman SG. Non-psychotropic phytocannabinoid interactions with voltage-gated sodium channels: An update on cannabidiol and cannabigerol. Front Physiol 2022; 13:1066455. [PMID: 36439273 PMCID: PMC9691960 DOI: 10.3389/fphys.2022.1066455] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 10/31/2022] [Indexed: 09/10/2023] Open
Abstract
Phytocannabinoids, found in the plant, Cannabis sativa, are an important class of natural compounds with physiological effects. These compounds can be generally divided into two classes: psychoactive and non-psychoactive. Those which do not impart psychoactivity are assumed to predominantly function via endocannabinoid receptor (CB) -independent pathways and molecular targets, including other receptors and ion channels. Among these targets, the voltage-gated sodium (Nav) channels are particularly interesting due to their well-established role in electrical signalling in the nervous system. The interactions between the main non-psychoactive phytocannabinoid, cannabidiol (CBD), and Nav channels were studied in detail. In addition to CBD, cannabigerol (CBG), is another non-psychoactive molecule implicated as a potential therapeutic for several conditions, including pain via interactions with Nav channels. In this mini review, we provide an update on the interactions of Nav channels with CBD and CBG.
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Affiliation(s)
| | - Sulayman D. Dib-Hajj
- Department of Neurology, Yale University School of Medicine, New Haven, CT, United States
| | - Samuel J. Goodchild
- Department of Cellular and Molecular Biology, Xenon Pharmaceuticals Inc., Burnaby, BC, Canada
| | - Peter C. Ruben
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - Stephen G. Waxman
- Department of Neurology, Yale University School of Medicine, New Haven, CT, United States
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16
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George K, Lopez-Mateos D, Abd El-Aziz TM, Xiao Y, Kline J, Bao H, Raza S, Stockand JD, Cummins TR, Fornelli L, Rowe MP, Yarov-Yarovoy V, Rowe AH. Structural and Functional Characterization of a Novel Scorpion Toxin that Inhibits NaV1.8 via Interactions With the DI Voltage Sensor and DII Pore Module. Front Pharmacol 2022; 13:846992. [PMID: 35662692 PMCID: PMC9160825 DOI: 10.3389/fphar.2022.846992] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Accepted: 04/05/2022] [Indexed: 11/30/2022] Open
Abstract
Voltage-gated sodium channel NaV1.8 regulates transmission of pain signals to the brain. While NaV1.8 has the potential to serve as a drug target, the molecular mechanisms that shape NaV1.8 gating are not completely understood, particularly mechanisms that couple activation to inactivation. Interactions between toxin producing animals and their predators provide a novel approach for investigating NaV structure-function relationships. Arizona bark scorpions produce Na+ channel toxins that initiate pain signaling. However, in predatory grasshopper mice, toxins inhibit NaV1.8 currents and block pain signals. A screen of synthetic peptide toxins predicted from bark scorpion venom showed that peptide NaTx36 inhibited Na+ current recorded from a recombinant grasshopper mouse NaV1.8 channel (OtNaV1.8). Toxin NaTx36 hyperpolarized OtNaV1.8 activation, steady-state fast inactivation, and slow inactivation. Mutagenesis revealed that the first gating charge in the domain I (DI) S4 voltage sensor and an acidic amino acid (E) in the DII SS2 – S6 pore loop are critical for the inhibitory effects of NaTx36. Computational modeling showed that a DI S1 – S2 asparagine (N) stabilizes the NaTx36 – OtNaV1.8 complex while residues in the DI S3 – S4 linker and S4 voltage sensor form electrostatic interactions that allow a toxin glutamine (Q) to contact the first S4 gating charge. Surprisingly, the models predicted that NaTx36 contacts amino acids in the DII S5 – SS1 pore loop instead of the SS2 – S6 loop; the DII SS2 – S6 loop motif (QVSE) alters the conformation of the DII S5 – SS1 pore loop, enhancing allosteric interactions between toxin and the DII S5 – SS1 pore loop. Few toxins have been identified that modify NaV1.8 gating. Moreover, few toxins have been described that modify sodium channel gating via the DI S4 voltage sensor. Thus, NaTx36 and OtNaV1.8 provide tools for investigating the structure-activity relationship between channel activation and inactivation gating, and the connection to alternative pain phenotypes.
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Affiliation(s)
- Kiran George
- Department of Biology, University of Oklahoma, Norman, OK, United States
| | - Diego Lopez-Mateos
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, United States
- Biophysics Graduate Group, University of California, Davis, Davis, CA, United States
| | - Tarek Mohamed Abd El-Aziz
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center San Antonio, San Antonio, TX, United States
- Zoology Department, Faculty of Science, Minia University, El-Minia, Egypt
- Amsaal Venom Farm L.L.C., Abu Dhabi, United Arab Emirates
| | - Yucheng Xiao
- Department of Biology, School of Science, Indiana University-Purdue University Indianapolis, Indianapolis, IN, United States
| | - Jake Kline
- Department of Biology, University of Oklahoma, Norman, OK, United States
| | - Hong Bao
- Department of Biology, University of Oklahoma, Norman, OK, United States
| | - Syed Raza
- Department of Biology, University of Oklahoma, Norman, OK, United States
| | - James D. Stockand
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center San Antonio, San Antonio, TX, United States
| | - Theodore R. Cummins
- Department of Biology, School of Science, Indiana University-Purdue University Indianapolis, Indianapolis, IN, United States
| | - Luca Fornelli
- Department of Biology, University of Oklahoma, Norman, OK, United States
| | - Matthew P. Rowe
- Department of Biology, University of Oklahoma, Norman, OK, United States
| | - Vladimir Yarov-Yarovoy
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, United States
- Biophysics Graduate Group, University of California, Davis, Davis, CA, United States
- Department of Anesthesiology and Pain Medicine, University of California, Davis, Davis, CA, United States
| | - Ashlee H. Rowe
- Department of Biology, University of Oklahoma, Norman, OK, United States
- Graduate Program in Cellular and Behavioral Neurobiology, University of Oklahoma, Norman, OK, United States
- *Correspondence: Ashlee H. Rowe,
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17
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Lignani G. Unblock the Block! Preventing Inhibitory Failure to Maintain Inhibitory Restraint. Epilepsy Curr 2022; 22:244-245. [PMID: 36187146 PMCID: PMC9483764 DOI: 10.1177/15357597221098808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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18
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Fouda MA, Ghovanloo MR, Ruben PC. Late sodium current: incomplete inactivation triggers seizures, myotonias, arrhythmias, and pain syndromes. J Physiol 2022; 600:2835-2851. [PMID: 35436004 DOI: 10.1113/jp282768] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 04/12/2022] [Indexed: 11/08/2022] Open
Abstract
Acquired and inherited dysfunction in voltage-gated sodium channels underlies a wide range of diseases. "In addition to the defects in trafficking and expression, sodium channelopathies are also caused by dysfunction in one or several gating properties, for instance activation or inactivation. Disruption of the channel inactivation leads to the increased late sodium current, which is a common defect in seizure disorders, cardiac arrhythmias skeletal muscle myotonia and pain. An increase in late sodium current leads to repetitive action potential in neurons and skeletal muscles, and prolonged action potential duration in the heart. In this topical review, we compare the effects of late sodium current in brain, heart, skeletal muscle, and peripheral nerves. Abstract figure legend Shows cartoon illustration of general Nav channel transitions between (1) resting, (2) open, and (3) fast inactivated states. Disruption of the inactivation process exacerbates (4) late sodium currents. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Mohamed A Fouda
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, Canada.,Department of Pharmacology and Toxicology, Alexandria University, Alexandria, Egypt
| | | | - Peter C Ruben
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, Canada
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19
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Wisedchaisri G, Gamal El-Din TM. Druggability of Voltage-Gated Sodium Channels-Exploring Old and New Drug Receptor Sites. Front Pharmacol 2022; 13:858348. [PMID: 35370700 PMCID: PMC8968173 DOI: 10.3389/fphar.2022.858348] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 03/01/2022] [Indexed: 01/12/2023] Open
Abstract
Voltage-gated ion channels are important drug targets because they play crucial physiological roles in both excitable and non-excitable cells. About 15% of clinical drugs used for treating human diseases target ion channels. However, most of these drugs do not provide sufficient specificity to a single subtype of the channels and their off-target side effects can be serious and sometimes fatal. Recent advancements in imaging techniques have enabled us for the first time to visualize unique and hidden parts of voltage-gated sodium channels in different structural conformations, and to develop drugs that further target a selected functional state in each channel subtype with the potential for high precision and low toxicity. In this review we describe the druggability of voltage-gated sodium channels in distinct functional states, which could potentially be used to selectively target the channels. We review classical drug receptors in the channels that have recently been structurally characterized by cryo-electron microscopy with natural neurotoxins and clinical drugs. We further examine recent drug discoveries for voltage-gated sodium channels and discuss opportunities to use distinct, state-dependent receptor sites in the voltage sensors as unique drug targets. Finally, we explore potential new receptor sites that are currently unknown for sodium channels but may be valuable for future drug discovery. The advancement presented here will help pave the way for drug development that selectively targets voltage-gated sodium channels.
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Affiliation(s)
- Goragot Wisedchaisri
- Department of Pharmacology, University of Washington, Seattle, WA, United States
| | - Tamer M Gamal El-Din
- Department of Pharmacology, University of Washington, Seattle, WA, United States
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20
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Genetic Analysis of Sodium Channel Genes in Pediatric Epilepsy Patients of Pakistan. Genet Res (Camb) 2022; 2022:1168703. [PMID: 35136380 PMCID: PMC8817870 DOI: 10.1155/2022/1168703] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 12/20/2021] [Accepted: 01/12/2022] [Indexed: 11/18/2022] Open
Abstract
Epilepsy affects millions of people worldwide. Although antiepileptic drugs work for the majority of epileptic patients, these drugs do not work for some of the patients, subjecting them to drug-resistant epilepsy (DRE). Voltage-gated sodium channels act as targets for a number of antiepileptic drugs, and the genes encoding these channels can play a crucial role in developing drug-resistant epilepsy. This case-control (100 control: 101patients) study evaluated the association of sodium channel genes SCN1A and SCN2A with drug-resistant epilepsy. The cases were further accounted in two categories, drug-resistant and drug-responsive epileptic patients. The polymorphic sites rs794726754, rs1057518252, rs121918809, rs12191792, rs121917932, c.730 G > T, c.735 G > T, c.736 A > T, rs10167228, and rs2298771 of the SCN1A gene and rs17183814 of SCN2A gene were selected for mutational analysis. The DNA was isolated, amplified by PCR, and then, was run through 1% agarose gel. The sequencing was performed, and the sequences were observed through BioEdit software for any change in DNA sequence. In our study, no polymorphism was observed in the studied SNPs except for rs2298771. For rs2298771, a significant difference existed in the distribution of genotypic and allelic frequencies (p < 0.01) among the case and control group. Furthermore, the genotypic and allelic frequencies of the two categories of cases (drug responder drug resistant) were calculated. The genotypic and allelic frequencies of drug-responsive and drug-resistant epileptic patients did not differ significantly (p > 0.01). Our study indicated that the rs2298771 polymorphism of SCN1A may not be associated with chance of developing DRE in the Pakistani population.
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21
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Choudhury K, Kasimova MA, McComas S, Howard RJ, Delemotte L. An open state of a voltage-gated sodium channel involving a π-helix and conserved pore-facing asparagine. Biophys J 2022; 121:11-22. [PMID: 34890580 PMCID: PMC8758419 DOI: 10.1016/j.bpj.2021.12.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 11/26/2021] [Accepted: 12/06/2021] [Indexed: 01/07/2023] Open
Abstract
Voltage-gated sodium (Nav) channels play critical roles in propagating action potentials and otherwise manipulating ionic gradients in excitable cells. These channels open in response to membrane depolarization, selectively permeating sodium ions until rapidly inactivating. Structural characterization of the gating cycle in this channel family has proved challenging, particularly due to the transient nature of the open state. A structure from the bacterium Magnetococcus marinus Nav (NavMs) was initially proposed to be open, based on its pore diameter and voltage-sensor conformation. However, the functional annotation of this model, and the structural details of the open state, remain disputed. In this work, we used molecular modeling and simulations to test possible open-state models of NavMs. The full-length experimental structure, termed here the α-model, was consistently dehydrated at the activation gate, indicating an inability to conduct ions. Based on a spontaneous transition observed in extended simulations, and sequence/structure comparison to other Nav channels, we built an alternative π-model featuring a helix transition and the rotation of a conserved asparagine residue into the activation gate. Pore hydration, ion permeation, and state-dependent drug binding in this model were consistent with an open functional state. This work thus offers both a functional annotation of the full-length NavMs structure and a detailed model for a stable Nav open state, with potential conservation in diverse ion-channel families.
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Affiliation(s)
- Koushik Choudhury
- Science for Life Laboratory, Department of Applied Physics, KTH Royal Institute of Technology, Solna, Sweden
| | - Marina A. Kasimova
- Science for Life Laboratory, Department of Applied Physics, KTH Royal Institute of Technology, Solna, Sweden
| | - Sarah McComas
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Rebecca J. Howard
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Lucie Delemotte
- Science for Life Laboratory, Department of Applied Physics, KTH Royal Institute of Technology, Solna, Sweden,Corresponding author
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22
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Le Cann K, Meents JE, Sudha Bhagavath Eswaran V, Dohrn MF, Bott R, Maier A, Bialer M, Hautvast P, Erickson A, Rolke R, Rothermel M, Körner J, Kurth I, Lampert A. Assessing the impact of pain-linked Nav1.7 variants: An example of two variants with no biophysical effect. Channels (Austin) 2021; 15:208-228. [PMID: 33487118 PMCID: PMC7833769 DOI: 10.1080/19336950.2020.1870087] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 12/23/2020] [Accepted: 12/23/2020] [Indexed: 11/30/2022] Open
Abstract
Mutations in the voltage-gated sodium channel Nav1.7 are linked to human pain. The Nav1.7/N1245S variant was described before in several patients suffering from primary erythromelalgia and/or olfactory hypersensitivity. We have identified this variant in a pain patient and a patient suffering from severe and life-threatening orthostatic hypotension. In addition, we report a female patient suffering from muscle pain and carrying the Nav1.7/E1139K variant. We tested both Nav1.7 variants by whole-cell voltage-clamp recordings in HEK293 cells, revealing a slightly enhanced current density for the N1245S variant when co-expressed with the β1 subunit. This effect was counteracted by an enhanced slow inactivation. Both variants showed similar voltage dependence of activation and steady-state fast inactivation, as well as kinetics of fast inactivation, deactivation, and use-dependency compared to WT Nav1.7. Finally, homology modeling revealed that the N1245S substitution results in different intramolecular interaction partners. Taken together, these experiments do not point to a clear pathogenic effect of either the N1245S or E1139K variant and suggest they may not be solely responsible for the patients' pain symptoms. As discussed previously for other variants, investigations in heterologous expression systems may not sufficiently mimic the pathophysiological situation in pain patients, and single nucleotide variants in other genes or modulatory proteins are necessary for these specific variants to show their effect. Our findings stress that biophysical investigations of ion channel mutations need to be evaluated with care and should preferably be supplemented with studies investigating the mutations in their context, ideally in human sensory neurons.
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Affiliation(s)
- Kim Le Cann
- Institute of Physiology, RWTH Aachen University Hospital, Aachen, Germany
| | - Jannis E. Meents
- Institute of Physiology, RWTH Aachen University Hospital, Aachen, Germany
| | | | - Maike F. Dohrn
- Department of Neurology, Medical Faculty, RWTH Aachen University Hospital, Aachen, Germany
| | - Raya Bott
- Institute of Physiology, RWTH Aachen University Hospital, Aachen, Germany
| | - Andrea Maier
- Department of Neurology, Medical Faculty, RWTH Aachen University Hospital, Aachen, Germany
| | - Martin Bialer
- Division of Clinical Metabolism of Medical Genetics and Human Genomics at Northwell Health System, New-York, United States
| | - Petra Hautvast
- Institute of Physiology, RWTH Aachen University Hospital, Aachen, Germany
| | - Andelain Erickson
- Institute of Physiology, RWTH Aachen University Hospital, Aachen, Germany
| | - Roman Rolke
- Department for Palliative Care, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Markus Rothermel
- Department of Chemosensation, AG Neuromodulation, Institute for Biology II, RWTH Aachen University, Aachen, 52074, Germany
| | - Jannis Körner
- Institute of Physiology, RWTH Aachen University Hospital, Aachen, Germany
- Department of Anaesthesiology, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Ingo Kurth
- Institute of Human Genetics, Medical Faculty, RWTH Aachen University Hospital, Aachen, Germany
| | - Angelika Lampert
- Institute of Physiology, RWTH Aachen University Hospital, Aachen, Germany
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Layer N, Sonnenberg L, Pardo González E, Benda J, Hedrich UBS, Lerche H, Koch H, Wuttke TV. Dravet Variant SCN1A A1783V Impairs Interneuron Firing Predominantly by Altered Channel Activation. Front Cell Neurosci 2021; 15:754530. [PMID: 34776868 PMCID: PMC8581729 DOI: 10.3389/fncel.2021.754530] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 09/28/2021] [Indexed: 11/23/2022] Open
Abstract
Dravet syndrome (DS) is a developmental epileptic encephalopathy mainly caused by functional NaV1.1 haploinsufficiency in inhibitory interneurons. Recently, a new conditional mouse model expressing the recurrent human p.(Ala1783Val) missense variant has become available. In this study, we provided an electrophysiological characterization of this variant in tsA201 cells, revealing both altered voltage-dependence of activation and slow inactivation without reduced sodium peak current density. Based on these data, simulated interneuron (IN) firing properties in a conductance-based single-compartment model suggested surprisingly similar firing deficits for NaV1.1A1783V and full haploinsufficiency as caused by heterozygous truncation variants. Impaired NaV1.1A1783V channel activation was predicted to have a significantly larger impact on channel function than altered slow inactivation and is therefore proposed as the main mechanism underlying IN dysfunction. The computational model was validated in cortical organotypic slice cultures derived from conditional Scn1aA1783V mice. Pan-neuronal activation of the p.Ala1783V in vitro confirmed a predicted IN firing deficit and revealed an accompanying reduction of interneuronal input resistance while demonstrating normal excitability of pyramidal neurons. Altered input resistance was fed back into the model for further refinement. Taken together these data demonstrate that primary loss of function (LOF) gating properties accompanied by altered membrane characteristics may match effects of full haploinsufficiency on the neuronal level despite maintaining physiological peak current density, thereby causing DS.
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Affiliation(s)
- Nikolas Layer
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Lukas Sonnenberg
- Institute for Neurobiology, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Emilio Pardo González
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Jan Benda
- Institute for Neurobiology, Eberhard Karls University Tübingen, Tübingen, Germany.,Bernstein Center for Computational Neuroscience, Eberhard Karls Universitat, Tübingen, Germany
| | - Ulrike B S Hedrich
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Holger Lerche
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Henner Koch
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany.,Department of Epileptology, Neurology, Rheinisch-Westfälische Technische Hochschule Aachen, Aachen, Germany
| | - Thomas V Wuttke
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany.,Department of Neurosurgery, University of Tübingen, Tübingen, Germany
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Disrupting Epileptiform Activity by Preventing Parvalbumin Interneuron Depolarization Block. J Neurosci 2021; 41:9452-9465. [PMID: 34611025 DOI: 10.1523/jneurosci.1002-20.2021] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 09/21/2021] [Accepted: 09/26/2021] [Indexed: 11/21/2022] Open
Abstract
Inhibitory synaptic mechanisms oppose epileptic network activity in the brain. The breakdown in this inhibitory restraint and propagation of seizure activity has been linked to the overwhelming of feedforward inhibition, which is provided in large part by parvalbumin-expressing (PV) interneurons in the cortex. The underlying cellular processes therefore represent potential targets for understanding and preventing the propagation of seizure activity. Here we use an optogenetic strategy to test the hypothesis that depolarization block in PV interneurons is a significant factor during the loss of inhibitory restraint. Depolarization block results from the inactivation of voltage-gated sodium channels and leads to impaired action potential firing. We used focal NMDA stimulation to elicit reproducible epileptiform discharges in hippocampal organotypic brain slices from male and female mice and combined this with targeted recordings from defined neuronal populations. Simultaneous patch-clamp recordings from PV interneurons and pyramidal neurons revealed epileptiform activity that was associated with an overwhelming of inhibitory synaptic mechanisms and the emergence of a partial, and then complete, depolarization block in PV interneurons. To counteract this depolarization block, we developed protocols for eliciting pulsed membrane hyperpolarization via the inhibitory opsin, archaerhodopsin. This optical approach was effective in counteracting cumulative inactivation of voltage-gated channels, maintaining PV interneuron action potential firing properties during the inhibitory restraint period, and reducing the probability of initiating epileptiform activity. These experiments support the idea that depolarization block is a point of weakness in feedforward inhibitory synaptic mechanisms and represents a target for preventing the initiation and spread of seizure activity.SIGNIFICANCE STATEMENT GABAA receptor-mediated synaptic transmission opposes seizure activity by establishing an inhibitory restraint against spreading excitation. Parvalbumin-expressing (PV) interneurons contribute significantly to this inhibitory restraint, but it has been suggested that these cells are overwhelmed as they enter a state of "depolarization block." Here we test the importance of this process by devising an optogenetic strategy to selectively relieve depolarization block in PV interneurons. By inducing brief membrane hyperpolarization, we show that it is possible to reduce depolarization block in PV interneurons, maintain their action potential firing in the face of strong excitation, and disrupt epileptiform activity in an in vitro model. This represents a proof of principle that targeting rate-limiting processes can strengthen the inhibitory restraint of epileptiform activity.
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The insecticide deltamethrin enhances sodium channel slow inactivation of human Nav1.9, Nav1.8 and Nav1.7. Toxicol Appl Pharmacol 2021; 428:115676. [PMID: 34389319 DOI: 10.1016/j.taap.2021.115676] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 07/13/2021] [Accepted: 08/08/2021] [Indexed: 01/05/2023]
Abstract
The insecticide deltamethrin of the pyrethroid class mainly targets voltage-gated sodium channels (Navs). Deltamethrin prolongs the opening of Navs by slowing down fast inactivation and deactivation. Pyrethroids are supposedly safe for humans, however, they have also been linked to the gulf-war syndrome, a neuropathic pain condition that can develop following exposure to certain chemicals. Inherited neuropathic pain conditions have been linked to mutations in the Nav subtypes Nav1.7, Nav1.8, and Nav1.9. Here, we examined the effect of deltamethrin on the human isoforms Nav1.7, Nav1.8, and Nav1.9_C4 (chimera containing the C-terminus of rat Nav1.4) heterologously expressed in HEK293T and ND7/23 cells using whole-cell patch-clamp electrophysiology. For all three Nav subtypes, we observed increased persistent and tail currents that are typical for Nav channels modified by deltamethrin. The most surprising finding was an enhanced slow inactivation induced by deltamethrin in all three Nav subtypes. An enhanced slow inactivation is contrary to the prolonged opening caused by pyrethroids and has not been described for deltamethrin or any other pyrethroid before. Furthermore, we found that the fraction of deltamethrin-modified channels increased use-dependently. However, for Nav1.8, the use-dependent potentiation occurred only when the holding potential was increased to -90 mV, a potential at which the tail currents decay more slowly. This indicates that use-dependent modification is due to an accumulation of tail currents. In summary, our findings support a novel mechanism whereby deltamethrin enhances slow inactivation of voltage-gated sodium channels, which may, depending on the cellular resting membrane potential, reduce neuronal excitability and counteract the well-described pyrethroid effects of prolonging channel opening.
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26
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Arribas-Blázquez M, Piniella D, Olivos-Oré LA, Bartolomé-Martín D, Leite C, Giménez C, Artalejo AR, Zafra F. Regulation of the voltage-dependent sodium channel Na V1.1 by AKT1. Neuropharmacology 2021; 197:108745. [PMID: 34375627 DOI: 10.1016/j.neuropharm.2021.108745] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 07/09/2021] [Accepted: 08/02/2021] [Indexed: 11/28/2022]
Abstract
The voltage-sensitive sodium channel NaV1.1 plays a critical role in regulating excitability of GABAergic neurons and mutations in the corresponding gene are associated to Dravet syndrome and other forms of epilepsy. The activity of this channel is regulated by several protein kinases. To identify novel regulatory kinases we screened a library of activated kinases and we found that AKT1 was able to directly phosphorylate NaV1.1. In vitro kinase assays revealed that the phosphorylation site was located in the C-terminal part of the large intracellular loop connecting domains I and II of NaV1.1, a region that is known to be targeted by other kinases like PKA and PKC. Electrophysiological recordings revealed that activated AKT1 strongly reduced peak Na+ currents and displaced the inactivation curve to more negative potentials in HEK-293 cell stably expressing NaV1.1. These alterations in current amplitude and steady-state inactivation were mimicked by SC79, a specific activator of AKT1, and largely reverted by triciribine, a selective inhibitor. Neurons expressing endogenous NaV1.1 in primary cultures were identified by expressing a fluorescent protein under the NaV1.1 promoter. There, we also observed a strong decrease in the current amplitude after addition of SC79, but small effects on the inactivation parameters. Altogether, we propose a novel mechanism that might regulate the excitability of neural networks in response to AKT1, a kinase that plays a pivotal role under physiological and pathological conditions, including epileptogenesis.
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Affiliation(s)
- Marina Arribas-Blázquez
- Centro de Biología Molecular Severo Ochoa, Facultad de Ciencias, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain; Department of Pharmacology and Toxicology, Veterinary Faculty, Universidad Complutense de Madrid, 28040, Madrid, Spain
| | - Dolores Piniella
- Centro de Biología Molecular Severo Ochoa, Facultad de Ciencias, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain; IdiPAZ, Instituto de Salud Carlos III, Madrid, Spain
| | - Luis A Olivos-Oré
- Department of Pharmacology and Toxicology, Veterinary Faculty, Universidad Complutense de Madrid, 28040, Madrid, Spain; Instituto Universitario de Investigación en Neuroquímica, Universidad Complutense de Madrid, 28040, Madrid, Spain
| | - David Bartolomé-Martín
- Centro de Biología Molecular Severo Ochoa, Facultad de Ciencias, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain; IdiPAZ, Instituto de Salud Carlos III, Madrid, Spain
| | - Cristiana Leite
- Centro de Biología Molecular Severo Ochoa, Facultad de Ciencias, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain
| | - Cecilio Giménez
- Centro de Biología Molecular Severo Ochoa, Facultad de Ciencias, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain; IdiPAZ, Instituto de Salud Carlos III, Madrid, Spain
| | - Antonio R Artalejo
- Department of Pharmacology and Toxicology, Veterinary Faculty, Universidad Complutense de Madrid, 28040, Madrid, Spain; Instituto Universitario de Investigación en Neuroquímica, Universidad Complutense de Madrid, 28040, Madrid, Spain
| | - Francisco Zafra
- Centro de Biología Molecular Severo Ochoa, Facultad de Ciencias, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain; IdiPAZ, Instituto de Salud Carlos III, Madrid, Spain.
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Abd El-Aziz TM, Xiao Y, Kline J, Gridley H, Heaston A, Linse KD, Ward MJ, Rokyta DR, Stockand JD, Cummins TR, Fornelli L, Rowe AH. Identification and Characterization of Novel Proteins from Arizona Bark Scorpion Venom That Inhibit Nav1.8, a Voltage-Gated Sodium Channel Regulator of Pain Signaling. Toxins (Basel) 2021; 13:toxins13070501. [PMID: 34357973 PMCID: PMC8310189 DOI: 10.3390/toxins13070501] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 07/14/2021] [Accepted: 07/16/2021] [Indexed: 12/17/2022] Open
Abstract
The voltage-gated sodium channel Nav1.8 is linked to neuropathic and inflammatory pain, highlighting the potential to serve as a drug target. However, the biophysical mechanisms that regulate Nav1.8 activation and inactivation gating are not completely understood. Progress has been hindered by a lack of biochemical tools for examining Nav1.8 gating mechanisms. Arizona bark scorpion (Centruroides sculpturatus) venom proteins inhibit Nav1.8 and block pain in grasshopper mice (Onychomys torridus). These proteins provide tools for examining Nav1.8 structure–activity relationships. To identify proteins that inhibit Nav1.8 activity, venom samples were fractioned using liquid chromatography (reversed-phase and ion exchange). A recombinant Nav1.8 clone expressed in ND7/23 cells was used to identify subfractions that inhibited Nav1.8 Na+ current. Mass-spectrometry-based bottom-up proteomic analyses identified unique peptides from inhibitory subfractions. A search of the peptides against the AZ bark scorpion venom gland transcriptome revealed four novel proteins between 40 and 60% conserved with venom proteins from scorpions in four genera (Centruroides, Parabuthus, Androctonus, and Tityus). Ranging from 63 to 82 amino acids, each primary structure includes eight cysteines and a “CXCE” motif, where X = an aromatic residue (tryptophan, tyrosine, or phenylalanine). Electrophysiology data demonstrated that the inhibitory effects of bioactive subfractions can be removed by hyperpolarizing the channels, suggesting that proteins may function as gating modifiers as opposed to pore blockers.
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Affiliation(s)
- Tarek Mohamed Abd El-Aziz
- Department of Cellular & Integrative Physiology, University of Texas Health Science Center San Antonio, San Antonio, TX 78229, USA; (T.M.A.E.-A.); (J.D.S.)
- Zoology Department, Faculty of Science, Minia University, El-Minia 61519, Egypt
| | - Yucheng Xiao
- Department of Biology, School of Science, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA; (Y.X.); (T.R.C.)
| | - Jake Kline
- Department of Biology, University of Oklahoma, 730 Van Vleet Oval, Norman, OK 73019, USA; (J.K.); (H.G.); (A.H.); (L.F.)
| | - Harold Gridley
- Department of Biology, University of Oklahoma, 730 Van Vleet Oval, Norman, OK 73019, USA; (J.K.); (H.G.); (A.H.); (L.F.)
| | - Alyse Heaston
- Department of Biology, University of Oklahoma, 730 Van Vleet Oval, Norman, OK 73019, USA; (J.K.); (H.G.); (A.H.); (L.F.)
| | - Klaus D. Linse
- Bio-Synthesis Inc., 612 E. Main Street, Lewisville, TX 75057, USA;
| | - Micaiah J. Ward
- Department of Biological Sciences, Florida State University, 319 Stadium Drive, Tallahassee, FL 32306, USA; (M.J.W.); (D.R.R.)
| | - Darin R. Rokyta
- Department of Biological Sciences, Florida State University, 319 Stadium Drive, Tallahassee, FL 32306, USA; (M.J.W.); (D.R.R.)
| | - James D. Stockand
- Department of Cellular & Integrative Physiology, University of Texas Health Science Center San Antonio, San Antonio, TX 78229, USA; (T.M.A.E.-A.); (J.D.S.)
| | - Theodore R. Cummins
- Department of Biology, School of Science, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA; (Y.X.); (T.R.C.)
| | - Luca Fornelli
- Department of Biology, University of Oklahoma, 730 Van Vleet Oval, Norman, OK 73019, USA; (J.K.); (H.G.); (A.H.); (L.F.)
| | - Ashlee H. Rowe
- Department of Biology, University of Oklahoma, 730 Van Vleet Oval, Norman, OK 73019, USA; (J.K.); (H.G.); (A.H.); (L.F.)
- Correspondence: ; Tel.: +1-936-577-5782
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Cannabidiol Inhibition of Murine Primary Nociceptors: Tight Binding to Slow Inactivated States of Na v1.8 Channels. J Neurosci 2021; 41:6371-6387. [PMID: 34131037 DOI: 10.1523/jneurosci.3216-20.2021] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2020] [Revised: 05/11/2021] [Accepted: 06/04/2021] [Indexed: 02/06/2023] Open
Abstract
The nonpsychoactive phytocannabinoid cannabidiol (CBD) has been shown to have analgesic effects in animal studies but little is known about its mechanism of action. We examined the effects of CBD on intrinsic excitability of primary pain-sensing neurons. Studying acutely dissociated capsaicin-sensitive mouse DRG neurons at 37°C, we found that CBD effectively inhibited repetitive action potential firing, from 15-20 action potentials evoked by 1 s current injections in control to 1-3 action potentials with 2 μm CBD. Reduction of repetitive firing was accompanied by a reduction of action potential height, widening of action potentials, reduction of the afterhyperpolarization, and increased propensity to enter depolarization block. Voltage-clamp experiments showed that CBD inhibited both TTX-sensitive and TTX-resistant (TTX-R) sodium currents in a use-dependent manner. CBD showed strong state-dependent inhibition of TTX-R channels, with fast binding to inactivated channels during depolarizations and slow unbinding on repolarization. CBD alteration of channel availability at various voltages suggested that CBD binds especially tightly [K d (dissociation constant), ∼150 nm] to the slow inactivated state of TTX-R channels, which can be substantially occupied at voltages as negative as -40 mV. Remarkably, CBD was more potent in inhibiting TTX-R channels and inhibiting action potential firing than the local anesthetic bupivacaine. We conclude that CBD might produce some of its analgesic effects by direct effects on neuronal excitability, with tight binding to the slow inactivated state of Nav1.8 channels contributing to effective inhibition of repetitive firing by modest depolarizations.SIGNIFICANCE STATEMENT Cannabidiol (CBD) has been shown to inhibit pain in various rodent models, but the mechanism of this effect is unknown. We describe the ability of CBD to inhibit repetitive action potential firing in primary nociceptive neurons from mouse dorsal root ganglia and analyze the effects on voltage-dependent sodium channels. We find that CBD interacts with TTX-resistant sodium channels in a state-dependent manner suggesting particularly tight binding to slow inactivated states of Nav1.8 channels, which dominate the overall inactivation of Nav1.8 channels for small maintained depolarizations from the resting potential. The results suggest that CBD can exert analgesic effects in part by directly inhibiting repetitive firing of primary nociceptors and suggest a strategy of identifying compounds that bind selectively to slow inactivated states of Nav1.8 channels for developing effective analgesics.
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29
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Ghovanloo MR, Ruben PC. Cannabidiol and Sodium Channel Pharmacology: General Overview, Mechanism, and Clinical Implications. Neuroscientist 2021; 28:318-334. [PMID: 34027742 PMCID: PMC9344566 DOI: 10.1177/10738584211017009] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Voltage-gated sodium (Nav) channels initiate action potentials in excitable tissues. Altering these channels' function can lead to many pathophysiological conditions. Nav channels are composed of several functional and structural domains that could be targeted pharmacologically as potential therapeutic means against various neurological conditions. Mutations in Nav channels have been suggested to underlie various clinical syndromes in different tissues and in association with conditions ranging from epileptic to muscular problems. Treating those mutations that increase the excitability of Nav channels requires inhibitors that could effectively reduce channel firing. The main non-psychotropic constituent of the cannabis plant, cannabidiol (CBD), has recently gained interest as a viable compound to treat some of the conditions that are associated with Nav malfunctions. In this review, we discuss an overview of Nav channels followed by an in-depth description of the interactions of CBD and Nav channels. We conclude with some clinical implications of CBD use against Nav hyperexcitability based on a series of preclinical studies published to date, with a focus on Nav/CBD interactions.
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Affiliation(s)
- Mohammad-Reza Ghovanloo
- Department of Biomedical Physiology & Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada.,Department of Neurology, Yale University School of Medicine, New Haven, CT, USA.,Center for Neuroscience & Regeneration Research, Yale University, West Haven, CT, USA
| | - Peter C Ruben
- Department of Biomedical Physiology & Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
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30
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Yang R, Qian R, Chen K, Yi W, Sima X. Genetic polymorphisms in SCN2A are not associated with epilepsy risk and AEDs response: evidence from a meta-analysis. Neurol Sci 2021; 42:2705-2711. [PMID: 33914194 DOI: 10.1007/s10072-021-05242-x] [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: 08/21/2020] [Accepted: 04/09/2021] [Indexed: 02/08/2023]
Abstract
BACKGROUND Previous studies have investigated the association between rs2304016 and rs17183814 polymorphisms in sodium voltage-gated channel alpha subunit 2 (SCN2A) and epilepsy risk and responsiveness to antiepileptic drugs (AEDs) but with conflicting results. Our aim was to reevaluate the relationship by performing a systematic review and meta-analysis. METHODS By searching PubMed, Medline, and CNKI, 14 studies were selected. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were computed to measure the association between rs17183814 and rs2304016 polymorphisms and the risk of epilepsy and AEDs response using the fixed-effects model or the random-effects model. RESULTS No significant association between the rs17183814 in SCN2A and the risk of epilepsy was observed (heterozygous comparison: OR = 0.78, 95% CI: 0.61-1.00; homozygous comparison: OR = 1.34, 95% CI: 0.63-2.86; dominant model: OR = 0.82, 95% CI: 0.64-1.04; recessive model: OR = 1.44, 95% CI: 0.68-3.05; allele comparison: OR = 0.88, 95%CI: 0.71-1.10). Moreover, neither the rs17183814 nor the rs2304016 was associated with AEDs response. CONCLUSION This meta-analysis suggests that the rs17183814 and rs2304016 polymorphisms in SCN2A are not associated with the risk of epilepsy and response to AEDs.
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Affiliation(s)
- Ruiqing Yang
- West China School of Medicine, Sichuan University, Chengdu, 610041, Sichuan, China
| | - Ruiyi Qian
- West China School of Medicine, Sichuan University, Chengdu, 610041, Sichuan, China
| | - Kerun Chen
- West China School of Medicine, Sichuan University, Chengdu, 610041, Sichuan, China
| | - Wei Yi
- West China School of Medicine, Sichuan University, Chengdu, 610041, Sichuan, China
| | - Xiutian Sima
- Department of Neurosurgery, West China Hospital, Sichuan University, Chengdu, 610041, Sichuan, China.
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31
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Suzuki T, Yamato S. Oxazosulfyl, a Novel Sulfyl Insecticide, Binds to and Stabilizes the Voltage-Gated Sodium Channels in the Slow-Inactivated State. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2021; 69:4048-4055. [PMID: 33793218 DOI: 10.1021/acs.jafc.0c04617] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Oxazosulfyl is the first representative of a novel sulfyl class of insecticides with a potent and cross-spectrum insecticidal activity, albeit with an unclear mechanism of action. As a potential agent of pest control in rice fields, we investigated the action of oxazosulfyl on the nervous system and voltage-gated sodium channels in insects. After the injection of 10 μg of oxazosulfyl, American cockroaches (Periplaneta americana) were quickly paralyzed, which persisted for more than 7 days. Extracellular recordings revealed a depressed spontaneous nerve activity in the cockroaches injected with oxazosulfyl, which specifically affected the voltage-gated sodium channels (in German cockroaches (Blattella germanica) expressed in Xenopus oocytes) in the slow-inactivated state resulting in the inhibition of sodium currents. The potency of oxazosulfyl and other sodium channel blockers to block sodium channels was consistent with their insecticidal activity. Thus, we conclude that the action mode of oxazosulfyl involves the state-dependent blockage of voltage-gated sodium channels.
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Affiliation(s)
- Tatsuya Suzuki
- Health & Crop Sciences Research Laboratory, Sumitomo Chemical Co., Ltd., 2-1 Takatsukasa 4-chome, Takarazuka, Hyogo 665-8555, Japan
| | - Seiji Yamato
- Health & Crop Sciences Research Laboratory, Sumitomo Chemical Co., Ltd., 2-1 Takatsukasa 4-chome, Takarazuka, Hyogo 665-8555, Japan
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32
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Mantegazza M, Cestèle S, Catterall WA. Sodium channelopathies of skeletal muscle and brain. Physiol Rev 2021; 101:1633-1689. [PMID: 33769100 DOI: 10.1152/physrev.00025.2020] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Voltage-gated sodium channels initiate action potentials in nerve, skeletal muscle, and other electrically excitable cells. Mutations in them cause a wide range of diseases. These channelopathy mutations affect every aspect of sodium channel function, including voltage sensing, voltage-dependent activation, ion conductance, fast and slow inactivation, and both biosynthesis and assembly. Mutations that cause different forms of periodic paralysis in skeletal muscle were discovered first and have provided a template for understanding structure, function, and pathophysiology at the molecular level. More recent work has revealed multiple sodium channelopathies in the brain. Here we review the well-characterized genetics and pathophysiology of the periodic paralyses of skeletal muscle and then use this information as a foundation for advancing our understanding of mutations in the structurally homologous α-subunits of brain sodium channels that cause epilepsy, migraine, autism, and related comorbidities. We include studies based on molecular and structural biology, cell biology and physiology, pharmacology, and mouse genetics. Our review reveals unexpected connections among these different types of sodium channelopathies.
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Affiliation(s)
- Massimo Mantegazza
- Université Cote d'Azur, Valbonne-Sophia Antipolis, France.,CNRS UMR7275, Institut de Pharmacologie Moléculaire et Cellulaire, Valbonne-Sophia Antipolis, France.,INSERM, Valbonne-Sophia Antipolis, France
| | - Sandrine Cestèle
- Université Cote d'Azur, Valbonne-Sophia Antipolis, France.,CNRS UMR7275, Institut de Pharmacologie Moléculaire et Cellulaire, Valbonne-Sophia Antipolis, France
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Li M, Zhong R, Lu Y, Zhao Q, Li G, Lin W. Association Between SCN1A rs2298771, SCN1A rs10188577, SCN2A rs17183814, and SCN2A rs2304016 Polymorphisms and Responsiveness to Antiepileptic Drugs: A Meta-Analysis. Front Neurol 2021; 11:591828. [PMID: 33519675 PMCID: PMC7840883 DOI: 10.3389/fneur.2020.591828] [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: 08/05/2020] [Accepted: 11/27/2020] [Indexed: 12/18/2022] Open
Abstract
Background:SCN1A and SCN2A genes have been reported to be associated with the efficacy of single and combined antiepileptic therapy, but the results remain contradictory. Previous meta-analyses on this topic mainly focused on the SCN1A rs3812718 polymorphism. However, meta-analyses focused on SCN1A rs2298771, SCN1A rs10188577, SCN2A rs17183814, or SCN2A rs2304016 polymorphisms are scarce or non-existent. Objective: We aimed to conduct a meta-analysis to determine the effects of SCN1A rs2298771, SCN1A rs10188577, SCN2A rs17183814, and SCN2A rs2304016 polymorphisms on resistance to antiepileptic drugs (AEDs). Methods: We searched the PubMed, Embase, Cochrane Library, WANFANG, and CNKI databases up to June 2020 to collect studies on the association of SCN1A and SCN2A polymorphisms with reactivity to AEDs. We calculated the pooled odds ratios (ORs) under the allelic, homozygous, heterozygous, dominant, and recessive genetic models to identify the association between the four single-nucleotide polymorphisms (SNPs) and resistance to AEDs. Results: Our meta-analysis included 19 eligible studies. The results showed that the SCN1A rs2298771 polymorphism was related to AED resistance in the allelic, homozygous, and recessive genetic models (G vs. A: OR = 1.20, 95% CI: 1.012–1.424; GG vs. AA: OR = 1.567, 95% CI: 1.147–2.142; GG vs. AA + AG: OR = 1.408, 95% CI: 1.053–1.882). The homozygous model remained significant after Bonferroni correction (P < 0.0125). Further subgroup analyses demonstrated the significance of the correlation in the dominant model in Caucasians (South Asians) after Bonferroni correction (GG + GA vs. AA: OR = 1.620, 95% CI: 1.165–2.252). However, no association between SCN1A rs2298771 polymorphism and resistance to AEDs was found in Asians or Caucasians (non-South Asians). For SCN1A rs10188577, SCN2A rs17183814, and SCN2A rs2304016 polymorphisms, the correlations with responsiveness to AEDs were not significant in the overall population nor in any subgroup after conducting the Bonferroni correction. The results for SCN1A rs2298771, SCN1A rs10188577, and SCN2A rs2304016 polymorphisms were stable and reliable according to sensitivity analysis and Begg and Egger tests. However, the results for SCN2A rs17183814 polymorphism have to be treated cautiously owing to the significant publication bias revealed by Begg and Egger tests. Conclusions: The present meta-analysis indicated that SCN1A rs2298771 polymorphism significantly affects resistance to AEDs in the overall population and Caucasians (South Asians). There were no significant correlations between SCN1A rs10188577, SCN2A rs17183814, and SCN2A rs2304016 polymorphisms and resistance to AEDs.
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Affiliation(s)
- Mengmeng Li
- Department of Neurology, The First Hospital of Jilin University, Changchun, China
| | - Rui Zhong
- Department of Neurology, The First Hospital of Jilin University, Changchun, China
| | - Yingxue Lu
- Department of Neurology, The First Hospital of Jilin University, Changchun, China
| | - Qian Zhao
- Department of Neurology, The First Hospital of Jilin University, Changchun, China
| | - Guangjian Li
- Department of Neurology, The First Hospital of Jilin University, Changchun, China
| | - Weihong Lin
- Department of Neurology, The First Hospital of Jilin University, Changchun, China
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Mohamed SA, Aldeaf SA, Elhassan R, Hussein A, Gassoum A, Abdrabo AEA. Association of SCN1A Mutations with Epilepsy among Sudanese Patients. NEUROSCIENCE AND MEDICINE 2021; 12:90-102. [DOI: 10.4236/nm.2021.123008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
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van Gendt MJ, Siebrecht M, Briaire JJ, Bohte SM, Frijns JHM. Short and long-term adaptation in the auditory nerve stimulated with high-rate electrical pulse trains are better described by a power law. Hear Res 2020; 398:108090. [PMID: 33070033 DOI: 10.1016/j.heares.2020.108090] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 09/02/2020] [Accepted: 09/22/2020] [Indexed: 01/18/2023]
Abstract
Despite the introduction of many new sound-coding strategies speech perception outcomes in cochlear implant listeners have leveled off. Computer models may help speed up the evaluation of new sound-coding strategies, but most existing models of auditory nerve responses to electrical stimulation include limited temporal detail, as the effects of longer stimulation, such as adaptation, are not well-studied. Measured neural responses to stimulation with both short (400 ms) and long (10 min) duration high-rate (5kpps) pulse trains were compared in terms of spike rate and vector strength (VS) with model outcomes obtained with different forms of adaptation. A previously published model combining biophysical and phenomenological approaches was adjusted with adaptation modeled as a single decaying exponent, multiple exponents and a power law. For long duration data, power law adaptation by far outperforms the single exponent model, especially when it is optimized per fiber. For short duration data, all tested models performed comparably well, with slightly better performance of the single exponent model for VS and of the power law model for the spike rates. The power law parameter sets obtained when fitted to the long duration data also yielded adequate predictions for short duration stimulation, and vice versa. The power law function can be approximated with multiple exponents, which is physiologically more viable. The number of required exponents depends on the duration of simulation; the 400 ms data was well-replicated by two exponents (23 and 212 ms), whereas the 10-minute data required at least seven exponents (ranging from 4 ms to 600 s). Adaptation of the auditory nerve to high-rate electrical stimulation can best be described by a power-law or a sum of exponents. This gives an adequate fit for both short and long duration stimuli, such as CI speech segments.
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Affiliation(s)
- M J van Gendt
- ENT-Department, Leiden University Medical Centre, PO Box 9600, Leiden 2300 RC, The Netherlands.
| | - M Siebrecht
- ENT-Department, Leiden University Medical Centre, PO Box 9600, Leiden 2300 RC, The Netherlands
| | - J J Briaire
- ENT-Department, Leiden University Medical Centre, PO Box 9600, Leiden 2300 RC, The Netherlands
| | - S M Bohte
- CWI, Center for Mathematics and Informatics, Amsterdam, The Netherlands
| | - J H M Frijns
- ENT-Department, Leiden University Medical Centre, PO Box 9600, Leiden 2300 RC, The Netherlands
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Tapia CM, Folorunso O, Singh AK, McDonough K, Laezza F. Effects of Deltamethrin Acute Exposure on Nav1.6 Channels and Medium Spiny Neurons of the Nucleus Accumbens. Toxicology 2020; 440:152488. [PMID: 32387285 DOI: 10.1016/j.tox.2020.152488] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 04/16/2020] [Accepted: 04/30/2020] [Indexed: 12/19/2022]
Abstract
Exposure to pyrethroids, a popular insecticide class that targets voltage-gated Na+ (Nav) channels, has been correlated to an increase in diagnosis of neurodevelopmental disorders, such as attention deficit hyperactive disorder (ADHD), in children. Dysregulation of medium spiny neurons (MSNs) firing in the nucleus accumbens (NAc) is thought to play a critical role in the pathophysiology of ADHD and other neurodevelopmental disorders. The Nav1.6 channel is the primary molecular determinant of MSN firing and is sensitive to modification by pyrethroids. Building on previous studies demonstrating that deltamethrin (DM), a commonly used pyrethroid, leads to use-dependent enhancement of sodium currents, we characterized the effect of the toxin on long-term inactivation (LTI) of the Nav1.6 channel, a parameter known to affect neuronal firing, and characterized changes in MSN intrinsic excitability. We employed whole-cell patch-clamp electrophysiology to measure sodium currents in HEK-293 cells stably expressing Nav1.6 channels and intrinsic excitability of MSNs in the brain slice preparation. We found that in response to repetitive stimulation acute exposure to 10 μM DM potentiated a build-up of residual sodium currents and modified availability of Nav1.6 by inducing LTI. In the NAc, DM modified MSN intrinsic excitability increasing evoked action potential firing frequency and inducing aberrant action potentials with low amplitude and depolarized voltage threshold, phenotypes that could be explained by DM induced changes on the Nav1.6 channel. These results provide a potential initial mechanism of toxicity of DM that could lead to disruption of the NAc circuitry overtime, increasing the risk of ADHD and other neurodevelopmental disorders.
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Affiliation(s)
- Cynthia M Tapia
- Department of Pharmacology & Toxicology, University of Texas Medical Branch, Galveston, Texas 77555, USA; NIEHS Enviornmental Toxicology Training Program, University of Texas Medical Branch, Galveston, Texas 77555, USA
| | - Oluwarotimi Folorunso
- Department of Pharmacology & Toxicology, University of Texas Medical Branch, Galveston, Texas 77555, USA
| | - Aditya K Singh
- Department of Pharmacology & Toxicology, University of Texas Medical Branch, Galveston, Texas 77555, USA
| | - Kathleen McDonough
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, Texas 77555, USA
| | - Fernanda Laezza
- Department of Pharmacology & Toxicology, University of Texas Medical Branch, Galveston, Texas 77555, USA.
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Dynamic clamp constructed phase diagram for the Hodgkin and Huxley model of excitability. Proc Natl Acad Sci U S A 2020; 117:3575-3582. [PMID: 32024761 PMCID: PMC7035484 DOI: 10.1073/pnas.1916514117] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Excitability-a threshold-governed transient in transmembrane voltage-is a fundamental physiological process that controls the function of the heart, endocrine, muscles, and neuronal tissues. The 1950s Hodgkin and Huxley explicit formulation provides a mathematical framework for understanding excitability, as the consequence of the properties of voltage-gated sodium and potassium channels. The Hodgkin-Huxley model is more sensitive to parametric variations of protein densities and kinetics than biological systems whose excitability is apparently more robust. It is generally assumed that the model's sensitivity reflects missing functional relations between its parameters or other components present in biological systems. Here we experimentally assembled excitable membranes using the dynamic clamp and voltage-gated potassium ionic channels (Kv1.3) expressed in Xenopus oocytes. We take advantage of a theoretically derived phase diagram, where the phenomenon of excitability is reduced to two dimensions defined as combinations of the Hodgkin-Huxley model parameters, to examine functional relations in the parameter space. Moreover, we demonstrate activity dependence and hysteretic dynamics over the phase diagram due to the impacts of complex slow inactivation kinetics. The results suggest that maintenance of excitability amid parametric variation is a low-dimensional, physiologically tenable control process. In the context of model construction, the results point to a potentially significant gap between high-dimensional models that capture the full measure of complexity displayed by ion channel function and the lower dimensionality that captures physiological function.
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Catterall WA, Lenaeus MJ, Gamal El-Din TM. Structure and Pharmacology of Voltage-Gated Sodium and Calcium Channels. Annu Rev Pharmacol Toxicol 2020; 60:133-154. [PMID: 31537174 DOI: 10.1146/annurev-pharmtox-010818-021757] [Citation(s) in RCA: 132] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Voltage-gated sodium and calcium channels are evolutionarily related transmembrane signaling proteins that initiate action potentials, neurotransmission, excitation-contraction coupling, and other physiological processes. Genetic or acquired dysfunction of these proteins causes numerous diseases, termed channelopathies, and sodium and calcium channels are the molecular targets for several major classes of drugs. Recent advances in the structural biology of these proteins using X-ray crystallography and cryo-electron microscopy have given new insights into the molecular basis for their function and pharmacology. Here we review this recent literature and integrate findings on sodium and calcium channels to reveal the structural basis for their voltage-dependent activation, fast and slow inactivation, ion conductance and selectivity, and complex pharmacology at the atomic level. We conclude with the theme that new understanding of the diseases and therapeutics of these channels will be derived from application of the emerging structural principles from these recent structural analyses.
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Affiliation(s)
- William A Catterall
- Department of Pharmacology and Division of General Internal Medicine, Department of Medicine, University of Washington, Seattle, Washington 98195, USA;
| | - Michael J Lenaeus
- Department of Pharmacology and Division of General Internal Medicine, Department of Medicine, University of Washington, Seattle, Washington 98195, USA;
| | - Tamer M Gamal El-Din
- Department of Pharmacology and Division of General Internal Medicine, Department of Medicine, University of Washington, Seattle, Washington 98195, USA;
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Angus M, Ruben P. Voltage gated sodium channels in cancer and their potential mechanisms of action. Channels (Austin) 2019; 13:400-409. [PMID: 31510893 PMCID: PMC6768049 DOI: 10.1080/19336950.2019.1666455] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 08/30/2019] [Accepted: 09/08/2019] [Indexed: 01/22/2023] Open
Abstract
Voltage gated sodium channels (VGSC) are implicated in cancer cell invasion and metastasis. However, the mechanism by which VGSC increase cell invasiveness and probability of metastasis is still unknown. In this review we outline lesser known functions of VGSC outside of action potential propagation, and the current understanding of the effects of VGSC in cancer. Finally, we discuss possible downstream effects of VGSC activation in cancer cells. After extensive review of the literature, the most likely role of VGSC in cancer is in the invadopodia, the leading edge of metastatic cancer cells. Sodium gradients are used to drive many biological processes in the body, and invadopodia may be similar. The function of the sodium hydrogen exchanger (NHE) and sodium calcium exchanger (NCX) are driven by sodium gradients. Voltage gated calcium channels, activated by membrane depolarization, are also capable of becoming activated in response to VGSC activity. Changes to hydrogen ion exchange or calcium handling have functional consequences for invadopodia and would explain the relationship between VGSC expression and invasiveness of cancer cells.
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Affiliation(s)
- Madeline Angus
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - Peter Ruben
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
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Deerasooriya Y, Berecki G, Kaplan D, Forster IC, Halgamuge S, Petrou S. Estimating neuronal conductance model parameters using dynamic action potential clamp. J Neurosci Methods 2019; 325:108326. [PMID: 31265869 DOI: 10.1016/j.jneumeth.2019.108326] [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: 03/27/2019] [Revised: 06/27/2019] [Accepted: 06/28/2019] [Indexed: 10/26/2022]
Abstract
BACKGROUND Parameterization of neuronal membrane conductance models relies on data acquired from current clamp (CC) or voltage clamp (VC) recordings. Although the CC approach provides key information on a neuron's firing properties, it is often difficult to disentangle the influence of multiple conductances that contribute to the excitation properties of a real neuron. Isolation of a single conductance using pharmacological agents or heterologous expression simplifies analysis but requires extensive VC evaluation to explore the complete state behavior of the channel of interest. NEW METHOD We present an improved parameterization approach that uses data derived from dynamic action potential clamp (DAPC) recordings to extract conductance equation parameters. We demonstrate the utility of the approach by applying it to the standard Hodgkin-Huxley conductance model although other conductance models could be easily incorporated as well. RESULTS Using a fully simulated setup we show that, with as few as five action potentials previously recorded in DAPC mode, sodium conductance equation parameters can be determined with average parameter errors of less than 4% while action potential firing accuracy approaches 100%. In real DAPC experiments, we show that by "training" our model with five or fewer action potentials, subsequent firing lasting for several seconds could be predicted with ˜96% mean firing rate accuracy and 94% temporal overlap accuracy. COMPARISON WITH EXISTING METHODS Our DAPC-based approach surpasses the accuracy of VC-based approaches for extracting conductance equation parameters with a significantly reduced temporal overhead. CONCLUSION DAPC-based approach will facilitate the rapid and systematic characterization of neuronal channelopathies.
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Affiliation(s)
- Y Deerasooriya
- Department of Mechanical Engineering, The University of Melbourne, Parkville, Victoria, Australia
| | - G Berecki
- Ion Channels and Disease Group, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria, Australia
| | - D Kaplan
- Ion Channels and Disease Group, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria, Australia
| | - I C Forster
- Ion Channels and Disease Group, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria, Australia
| | - S Halgamuge
- Department of Mechanical Engineering, The University of Melbourne, Parkville, Victoria, Australia; Research School of Engineering, College of Engineering & Computer Science, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - S Petrou
- Ion Channels and Disease Group, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria, Australia; Department of Medicine, Royal Melbourne Hospital, The University of Melbourne, Parkville, Victoria, Australia; ARC Centre for Integrated Brain Function, The University of Melbourne, Parkville, Victoria, Australia.
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Venugopal S, Seki S, Terman DH, Pantazis A, Olcese R, Wiedau-Pazos M, Chandler SH. Resurgent Na+ Current Offers Noise Modulation in Bursting Neurons. PLoS Comput Biol 2019; 15:e1007154. [PMID: 31226124 PMCID: PMC6608983 DOI: 10.1371/journal.pcbi.1007154] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Revised: 07/03/2019] [Accepted: 06/04/2019] [Indexed: 01/20/2023] Open
Abstract
Neurons utilize bursts of action potentials as an efficient and reliable way to encode information. It is likely that the intrinsic membrane properties of neurons involved in burst generation may also participate in preserving its temporal features. Here we examined the contribution of the persistent and resurgent components of voltage-gated Na+ currents in modulating the burst discharge in sensory neurons. Using mathematical modeling, theory and dynamic-clamp electrophysiology, we show that, distinct from the persistent Na+ component which is important for membrane resonance and burst generation, the resurgent Na+ can help stabilize burst timing features including the duration and intervals. Moreover, such a physiological role for the resurgent Na+ offered noise tolerance and preserved the regularity of burst patterns. Model analysis further predicted a negative feedback loop between the persistent and resurgent gating variables which mediate such gain in burst stability. These results highlight a novel role for the voltage-gated resurgent Na+ component in moderating the entropy of burst-encoded neural information.
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Affiliation(s)
- Sharmila Venugopal
- Department of Integrative Biology and Physiology, University of California Los Angeles, Los Angeles, CA, United States of America
| | - Soju Seki
- Department of Integrative Biology and Physiology, University of California Los Angeles, Los Angeles, CA, United States of America
| | - David H Terman
- Department of Mathematics, The Ohio State University, Columbus, OH, United States of America
| | - Antonios Pantazis
- Department of Anesthesiology & Perioperative Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, United States of America.,Division of Neurobiology Department of Clinical and Experimental Medicine (IKE) and Wallenberg Center for Molecular Medicine Linköping University 581 83 Linköping Sweden
| | - Riccardo Olcese
- Department of Anesthesiology & Perioperative Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, United States of America
| | - Martina Wiedau-Pazos
- Department of Neurology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, United States of America
| | - Scott H Chandler
- Department of Integrative Biology and Physiology, University of California Los Angeles, Los Angeles, CA, United States of America
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Bennett DL, Clark AJ, Huang J, Waxman SG, Dib-Hajj SD. The Role of Voltage-Gated Sodium Channels in Pain Signaling. Physiol Rev 2019; 99:1079-1151. [DOI: 10.1152/physrev.00052.2017] [Citation(s) in RCA: 256] [Impact Index Per Article: 51.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Acute pain signaling has a key protective role and is highly evolutionarily conserved. Chronic pain, however, is maladaptive, occurring as a consequence of injury and disease, and is associated with sensitization of the somatosensory nervous system. Primary sensory neurons are involved in both of these processes, and the recent advances in understanding sensory transduction and human genetics are the focus of this review. Voltage-gated sodium channels (VGSCs) are important determinants of sensory neuron excitability: they are essential for the initial transduction of sensory stimuli, the electrogenesis of the action potential, and neurotransmitter release from sensory neuron terminals. Nav1.1, Nav1.6, Nav1.7, Nav1.8, and Nav1.9 are all expressed by adult sensory neurons. The biophysical characteristics of these channels, as well as their unique expression patterns within subtypes of sensory neurons, define their functional role in pain signaling. Changes in the expression of VGSCs, as well as posttranslational modifications, contribute to the sensitization of sensory neurons in chronic pain states. Furthermore, gene variants in Nav1.7, Nav1.8, and Nav1.9 have now been linked to human Mendelian pain disorders and more recently to common pain disorders such as small-fiber neuropathy. Chronic pain affects one in five of the general population. Given the poor efficacy of current analgesics, the selective expression of particular VGSCs in sensory neurons makes these attractive targets for drug discovery. The increasing availability of gene sequencing, combined with structural modeling and electrophysiological analysis of gene variants, also provides the opportunity to better target existing therapies in a personalized manner.
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Affiliation(s)
- David L. Bennett
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom; Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, Connecticut; and Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut
| | - Alex J. Clark
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom; Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, Connecticut; and Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut
| | - Jianying Huang
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom; Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, Connecticut; and Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut
| | - Stephen G. Waxman
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom; Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, Connecticut; and Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut
| | - Sulayman D. Dib-Hajj
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom; Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, Connecticut; and Rehabilitation Research Center, Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut
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Gamal El-Din TM, Lenaeus MJ, Ramanadane K, Zheng N, Catterall WA. Molecular dissection of multiphase inactivation of the bacterial sodium channel Na VAb. J Gen Physiol 2018; 151:174-185. [PMID: 30510035 PMCID: PMC6363407 DOI: 10.1085/jgp.201711884] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 08/22/2018] [Accepted: 10/25/2018] [Indexed: 11/20/2022] Open
Abstract
Voltage-gated sodium channels have a conserved multiphase slow-inactivation process. Gamal El-Din et al. show that the early phase involves conformational changes at a critical threonine in the S6 segment, which are followed by a late phase mediated by the intracellular C-terminal domain. Homotetrameric bacterial voltage-gated sodium channels share major biophysical features with their more complex eukaryotic counterparts, including a slow-inactivation mechanism that reduces ion-conductance activity during prolonged depolarization through conformational changes in the pore. The bacterial sodium channel NaVAb activates at very negative membrane potentials and inactivates through a multiphase slow-inactivation mechanism. Early voltage-dependent inactivation during one depolarization is followed by late use-dependent inactivation during repetitive depolarization. Mutations that change the molecular volume of Thr206 in the pore-lining S6 segment can enhance or strongly block early voltage-dependent inactivation, suggesting that this residue serves as a molecular hub controlling the coupling of activation to inactivation. In contrast, truncation of the C-terminal tail enhances the early phase of inactivation yet completely blocks late use-dependent inactivation. Determination of the structure of a C-terminal tail truncation mutant and molecular modeling of conformational changes at Thr206 and the S6 activation gate led to a two-step model of these gating processes. First, bending of the S6 segment, local protein interactions dependent on the size of Thr206, and exchange of hydrogen-bonding partners at the level of Thr206 trigger pore opening followed by the early phase of voltage-dependent inactivation. Thereafter, conformational changes in the C-terminal tail lead to late use-dependent inactivation. These results have important implications for the sequence of conformational changes that lead to multiphase inactivation of NaVAb and other sodium channels.
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Affiliation(s)
| | - Michael J Lenaeus
- Department of Pharmacology, University of Washington, Seattle, WA.,Division of General Internal Medicine, Department of Medicine, University of Washington, Seattle, WA
| | - Karthik Ramanadane
- Department of Pharmacology, University of Washington, Seattle, WA.,École Normal Supérieure, Cachan, France
| | - Ning Zheng
- Department of Pharmacology, University of Washington, Seattle, WA.,Howard Hughes Medical Institute, University of Washington, Seattle, WA
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Suzuki T, Yamato S. Mode of action of piperovatine, an insecticidal piperamide isolated from Piper piscatorum (Piperaceae), against voltage-gated sodium channels. Neurotoxicology 2018; 69:288-295. [DOI: 10.1016/j.neuro.2018.07.021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 07/23/2018] [Accepted: 07/30/2018] [Indexed: 10/28/2022]
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45
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Grzywna ZJ, Borys P. On the significance of sodium ionic channels in analysis of the breast cancer metastaticity. Biosystems 2018; 177:34-38. [PMID: 30308232 DOI: 10.1016/j.biosystems.2018.10.007] [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: 08/20/2018] [Accepted: 10/05/2018] [Indexed: 11/25/2022]
Abstract
Using the results from previous modeling of the ball and chain inactivation of the potassium channels we try to model the inactivation of the NaV 1.5 sodium channels in adult and neonatal form. The (fast) inactivation of sodium channels differs from the inactivation of the potassium channels by the use of a inactivating hinge rather than a ball on a chain. The adult and neonatal variants of the channel differ mostly in a charged amino acid residue located on the extracellular side. We show that a drift caused by this residue is sufficient to describe the differences in inactivation between the two forms of the NaV 1.5. We use the survival probability, the patch-clamp measurable parameter, to discriminate between the cells of different metastaticity.
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Affiliation(s)
- Zbigniew J Grzywna
- Department of Physical Chemistry and Technology of Polymers, Section of Physics and Applied Mathematics, Silesian University of Technology, Ks. M. Strzody 9, 44-100 Gliwice, Poland
| | - Przemyslaw Borys
- Department of Physical Chemistry and Technology of Polymers, Section of Physics and Applied Mathematics, Silesian University of Technology, Ks. M. Strzody 9, 44-100 Gliwice, Poland.
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46
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Gamal El-Din TM, Lenaeus MJ, Catterall WA. Structural and Functional Analysis of Sodium Channels Viewed from an Evolutionary Perspective. Handb Exp Pharmacol 2018; 246:53-72. [PMID: 29043505 DOI: 10.1007/164_2017_61] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Voltage-gated sodium channels initiate and propagate action potentials in excitable cells. They respond to membrane depolarization through opening, followed by fast inactivation that terminates the sodium current. This ON-OFF behavior of voltage-gated sodium channels underlays the coding of information and its transmission from one location in the nervous system to another. In this review, we explore and compare structural and functional data from prokaryotic and eukaryotic channels to infer the effects of evolution on sodium channel structure and function.
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Affiliation(s)
- Tamer M Gamal El-Din
- Department of Pharmacology, University of Washington, Seattle, WA, 98195-7280, USA.
| | - Michael J Lenaeus
- Department of Pharmacology, University of Washington, Seattle, WA, 98195-7280, USA
| | - William A Catterall
- Department of Pharmacology, University of Washington, Seattle, WA, 98195-7280, USA
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47
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Abstract
A new study reveals that conformational flexibility in the pore of a voltage-gated sodium channel may underlie slow inactivation.
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48
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Cellular function given parametric variation in the Hodgkin and Huxley model of excitability. Proc Natl Acad Sci U S A 2018; 115:E8211-E8218. [PMID: 30111538 PMCID: PMC6126753 DOI: 10.1073/pnas.1808552115] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
How is reliable physiological function maintained in cells despite considerable variability in the values of key parameters of multiple interacting processes that govern that function? Here, we use the classic Hodgkin-Huxley formulation of the squid giant axon action potential to propose a possible approach to this problem. Although the full Hodgkin-Huxley model is very sensitive to fluctuations that independently occur in its many parameters, the outcome is in fact determined by simple combinations of these parameters along two physiological dimensions: structural and kinetic (denoted S and K, respectively). Structural parameters describe the properties of the cell, including its capacitance and the densities of its ion channels. Kinetic parameters are those that describe the opening and closing of the voltage-dependent conductances. The impacts of parametric fluctuations on the dynamics of the system-seemingly complex in the high-dimensional representation of the Hodgkin-Huxley model-are tractable when examined within the S-K plane. We demonstrate that slow inactivation, a ubiquitous activity-dependent feature of ionic channels, is a powerful local homeostatic control mechanism that stabilizes excitability amid changes in structural and kinetic parameters.
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49
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Tikhonov DB, Zhorov BS. Predicting Structural Details of the Sodium Channel Pore Basing on Animal Toxin Studies. Front Pharmacol 2018; 9:880. [PMID: 30131702 PMCID: PMC6090064 DOI: 10.3389/fphar.2018.00880] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 07/20/2018] [Indexed: 12/25/2022] Open
Abstract
Eukaryotic voltage-gated sodium channels play key roles in physiology and are targets for many toxins and medically important drugs. Physiology, pharmacology, and general architecture of the channels has long been the subject of intensive research in academia and industry. In particular, animal toxins such as tetrodotoxin, saxitoxin, and conotoxins have been used as molecular probes of the channel structure. More recently, X-ray structures of potassium and prokaryotic sodium channels allowed elaborating models of the toxin-channel complexes that integrated data from biophysical, electrophysiological, and mutational studies. Atomic level cryo-EM structures of eukaryotic sodium channels, which became available in 2017, show that the selectivity filter structure and other important features of the pore domain have been correctly predicted. This validates further employments of toxins and other small molecules as sensitive probes of fine structural details of ion channels.
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Affiliation(s)
- Denis B Tikhonov
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, Saint Petersburg, Russia
| | - Boris S Zhorov
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, Saint Petersburg, Russia.,Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada
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50
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Chatterjee S, Vyas R, Chalamalasetti SV, Sahu ID, Clatot J, Wan X, Lorigan GA, Deschênes I, Chakrapani S. The voltage-gated sodium channel pore exhibits conformational flexibility during slow inactivation. J Gen Physiol 2018; 150:1333-1347. [PMID: 30082431 PMCID: PMC6122925 DOI: 10.1085/jgp.201812118] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Accepted: 07/06/2018] [Indexed: 01/02/2023] Open
Abstract
Voltage-gated sodium channels undergo slow inactivation during prolonged depolarization by means of a mechanism that is poorly understood. Chatterjee et al. study this process spectroscopically and reveal conformational flexibility of the pore region in the slow-inactivated state. Slow inactivation in voltage-gated sodium channels (NaVs) directly regulates the excitability of neurons, cardiac myocytes, and skeletal muscles. Although NaV slow inactivation appears to be conserved across phylogenies—from bacteria to humans—the structural basis for this mechanism remains unclear. Here, using site-directed labeling and EPR spectroscopic measurements of membrane-reconstituted prokaryotic NaV homologues, we characterize the conformational dynamics of the selectivity filter region in the conductive and slow-inactivated states to determine the molecular events underlying NaV gating. Our findings reveal profound conformational flexibility of the pore in the slow-inactivated state. We find that the P1 and P2 pore helices undergo opposing movements with respect to the pore axis. These movements result in changes in volume of both the central and intersubunit cavities, which form pathways for lipophilic drugs that modulate slow inactivation. Our findings therefore provide novel insight into the molecular basis for state-dependent effects of lipophilic drugs on channel function.
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Affiliation(s)
- Soumili Chatterjee
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH
| | - Rajan Vyas
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH
| | | | - Indra D Sahu
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH
| | - Jérôme Clatot
- Heart and Vascular Research Center, Department of Medicine, Case Western Reserve University, Cleveland, OH
| | - Xiaoping Wan
- Heart and Vascular Research Center, Department of Medicine, Case Western Reserve University, Cleveland, OH
| | - Gary A Lorigan
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH
| | - Isabelle Deschênes
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH.,Heart and Vascular Research Center, Department of Medicine, Case Western Reserve University, Cleveland, OH
| | - Sudha Chakrapani
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH
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