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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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Zhang L, Tian J, Lin Z, Dong Z. Efficient Sodium Transmembrane Permeation through Helically Folded Nanopores with Natural Channel-Like Ion Selectivity. J Am Chem Soc 2024; 146:8500-8507. [PMID: 38483183 DOI: 10.1021/jacs.3c14736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/28/2024]
Abstract
The selective transmembrane permeation of sodium ions achieved by biomimetic chemistry shows great potential to solve the problem of sodium ion transport blockade in diseases, but its implementation faces enormous difficulties. Herein, we design and synthesize a series of helically folded nanopores by employing a quinoline-oxadiazole structural sequence to finely replicate the pentahydrate structure of sodium ions. Surprisingly, these nanopores are capable of achieving sodium transmembrane permeation with ion selectivity at the level of natural sodium channels, as observed in rationally designed nanopores (M1-M5) with Na+/K+ ion selectivity ratio of up to 20.4. Moreover, slight structural variations in nanopore structures can switch ion transport modes between the channel and carrier. We found that, compared to the carrier mode, the channel mode not only transports ions faster but also has higher ion selectivity during transmembrane conduction, clearly illustrating that the trade-off phenomenon between ion selectivity and transport activity does not occur between the two transport modes of channel and carrier. At the same time, we also found that the spatial position and numbers of coordination sites are crucial for the sodium ion selectivity of the nanopores. Moreover, carrier M1 reported in this work is totally superior to the commercial Na+ carrier ETH2120, especially in terms of Na+/K+ ion selectivity, thus being a potentially practical Na+ carrier. Our study provides a new paradigm on the rational design of sodium-specific synthetic nanopores, which will open up the possibility for the application of artificial sodium-specific transmembrane permeation in biomedicine and disease treatment.
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Affiliation(s)
- Lei Zhang
- State Key Laboratory of Supramolecular Structure and Materials, and Center for Supramolecular Chemical Biology, College of Chemistry, Jilin University, Changchun 130012, China
| | - Jun Tian
- State Key Laboratory of Supramolecular Structure and Materials, and Center for Supramolecular Chemical Biology, College of Chemistry, Jilin University, Changchun 130012, China
| | - Ze Lin
- State Key Laboratory of Supramolecular Structure and Materials, and Center for Supramolecular Chemical Biology, College of Chemistry, Jilin University, Changchun 130012, China
| | - Zeyuan Dong
- State Key Laboratory of Supramolecular Structure and Materials, and Center for Supramolecular Chemical Biology, College of Chemistry, Jilin University, Changchun 130012, China
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Gamal El-Din TM. When the Gates Swing Open Only: Arrhythmia Mutations That Target the Fast Inactivation Gate of Na v1.5. Cells 2022; 11:cells11233714. [PMID: 36496974 PMCID: PMC9735811 DOI: 10.3390/cells11233714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 11/17/2022] [Accepted: 11/17/2022] [Indexed: 11/23/2022] Open
Abstract
Nav1.5 is the main voltage-gated sodium channel found in cardiac muscle, where it facilitates the fast influx of Na+ ions across the cell membrane, resulting in the fast depolarization phase-phase 0 of the cardiac action potential. As a result, it plays a major role in determining the amplitude and the upstroke velocity of the cardiac impulse. Quantitively, cardiac sodium channel activates in less than a millisecond to trigger the cardiac action potential and inactivates within 2-3 ms to facilitate repolarization and return to the resting state in preparation for firing the next action potential. Missense mutations in the gene that encodes Nav1.5 (SCN5A), change these time constants which leads to a wide spectrum of cardiac diseases ranging from long QT syndrome type 3 (LQT3) to sudden cardiac death. In this mini-review I will focus on the missense mutations in the inactivation gate of Nav1.5 that results in arrhythmia, attempting to correlate the location of the missense mutation to their specific phenotype.
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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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Gamal El-Din TM, Lenaeus MJ. Fenestropathy of Voltage-Gated Sodium Channels. Front Pharmacol 2022; 13:842645. [PMID: 35222049 PMCID: PMC8873592 DOI: 10.3389/fphar.2022.842645] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 01/25/2022] [Indexed: 11/17/2022] Open
Abstract
Voltage-gated sodium channels (Nav) are responsible for the initiation and propagation of action potentials in excitable cells. From pain to heartbeat, these integral membrane proteins are the ignition stations for every sensation and action in human bodies. They are large (>200 kDa, 24 transmembrane helices) multi-domain proteins that couple changes in membrane voltage to the gating cycle of the sodium-selective pore. Nav mutations lead to a multitude of diseases - including chronic pain, cardiac arrhythmia, muscle illnesses, and seizure disorders - and a wide variety of currently used therapeutics block Nav. Despite this, the mechanisms of action of Nav blocking drugs are only modestly understood at this time and many questions remain to be answered regarding their state- and voltage-dependence, as well as the role of the hydrophobic membrane access pathways, or fenestrations, in drug ingress or egress. Nav fenestrations, which are pathways that connect the plasma membrane to the central cavity in the pore domain, were discovered through functional studies more than 40 years ago and once thought to be simple pathways. A variety of recent genetic, structural, and pharmacological data, however, shows that these fenestrations are actually key functional regions of Nav that modulate drug binding, lipid binding, and influence gating behaviors. We discovered that some of the disease mutations that cause arrhythmias alter amino acid residues that line the fenestrations of Nav1.5. This indicates that fenestrations may play a critical role in channel’s gating, and that individual genetic variation may also influence drug access through the fenestrations for resting/inactivated state block. In this review, we will discuss the channelopathies associated with these fenestrations, which we collectively name “Fenestropathy,” and how changes in the fenestrations associated with the opening of the intracellular gate could modulate the state-dependent ingress and egress of drugs binding in the central cavity of voltage gated sodium channels.
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Affiliation(s)
- Tamer M. Gamal El-Din
- Department of Pharmacology, University of Washington, Seattle, WA, United States
- *Correspondence: Tamer M. Gamal El-Din, ; Michael J. Lenaeus,
| | - Michael J. Lenaeus
- Department of Pharmacology, University of Washington, Seattle, WA, United States
- Division of General Internal Medicine, Department of Medicine, University of Washington, Seattle, WA, United States
- *Correspondence: Tamer M. Gamal El-Din, ; Michael J. Lenaeus,
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Wisedchaisri G, Tonggu L, Gamal El-Din TM, McCord E, Zheng N, Catterall WA. Structural Basis for High-Affinity Trapping of the Na V1.7 Channel in Its Resting State by Tarantula Toxin. Mol Cell 2021; 81:38-48.e4. [PMID: 33232657 PMCID: PMC8043720 DOI: 10.1016/j.molcel.2020.10.039] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 09/14/2020] [Accepted: 10/28/2020] [Indexed: 11/17/2022]
Abstract
Voltage-gated sodium channels initiate electrical signals and are frequently targeted by deadly gating-modifier neurotoxins, including tarantula toxins, which trap the voltage sensor in its resting state. The structural basis for tarantula-toxin action remains elusive because of the difficulty of capturing the functionally relevant form of the toxin-channel complex. Here, we engineered the model sodium channel NaVAb with voltage-shifting mutations and the toxin-binding site of human NaV1.7, an attractive pain target. This mutant chimera enabled us to determine the cryoelectron microscopy (cryo-EM) structure of the channel functionally arrested by tarantula toxin. Our structure reveals a high-affinity resting-state-specific toxin-channel interaction between a key lysine residue that serves as a "stinger" and penetrates a triad of carboxyl groups in the S3-S4 linker of the voltage sensor. By unveiling this high-affinity binding mode, our studies establish a high-resolution channel-docking and resting-state locking mechanism for huwentoxin-IV and provide guidance for developing future resting-state-targeted analgesic drugs.
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Affiliation(s)
| | - Lige Tonggu
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA
| | | | - Eedann McCord
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA
| | - Ning Zheng
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA; Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195, USA.
| | - William A Catterall
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA.
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7
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Structural basis for voltage-sensor trapping of the cardiac sodium channel by a deathstalker scorpion toxin. Nat Commun 2021; 12:128. [PMID: 33397917 PMCID: PMC7782738 DOI: 10.1038/s41467-020-20078-3] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 11/10/2020] [Indexed: 01/29/2023] Open
Abstract
Voltage-gated sodium (NaV) channels initiate action potentials in excitable cells, and their function is altered by potent gating-modifier toxins. The α-toxin LqhIII from the deathstalker scorpion inhibits fast inactivation of cardiac NaV1.5 channels with IC50 = 11.4 nM. Here we reveal the structure of LqhIII bound to NaV1.5 at 3.3 Å resolution by cryo-EM. LqhIII anchors on top of voltage-sensing domain IV, wedged between the S1-S2 and S3-S4 linkers, which traps the gating charges of the S4 segment in a unique intermediate-activated state stabilized by four ion-pairs. This conformational change is propagated inward to weaken binding of the fast inactivation gate and favor opening the activation gate. However, these changes do not permit Na+ permeation, revealing why LqhIII slows inactivation of NaV channels but does not open them. Our results provide important insights into the structural basis for gating-modifier toxin binding, voltage-sensor trapping, and fast inactivation of NaV channels.
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Beard JM, Shockett PE, O'Reilly JP. Substituted cysteine scanning in D1-S6 of the sodium channel hNav1.4 alters kinetics and structural interactions of slow inactivation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183129. [PMID: 31738900 DOI: 10.1016/j.bbamem.2019.183129] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2019] [Revised: 10/25/2019] [Accepted: 11/08/2019] [Indexed: 10/25/2022]
Abstract
Slow inactivation in voltage-gated Na+ channels (Navs) plays an important physiological role in excitable tissues (muscle, heart, nerves) and mutations that disrupt Nav slow inactivation can result in pathophysiologies (myotonia, arrhythmias, epilepsy). While the molecular mechanisms responsible for slow inactivation remain elusive, previous studies have suggested a role for the pore-lining D1-S6 helix. The goals of this research were to determine if (1) cysteine substitutions in D1-S6 affect gating kinetics and (2) methanethiosulfonate ethylammonium (MTSEA) accessibility changes in different kinetic states. Site-directed mutagenesis in the human skeletal muscle isoform hNav1.4 was used to substitute cysteine for eleven amino acids in D1-S6 from L433 to L443. Mutants were expressed in HEK cells and recorded from with whole-cell patch clamp. All mutations affected one or more baseline kinetics of the sodium channel, including activation, fast inactivation, and slow inactivation. Substitution of cysteine (for nonpolar residues) adjacent to polar residues destabilized slow inactivation in G434C, F436C, I439C, and L441C. Cysteine substitution without adjacent polar residues enhanced slow inactivation in L438C and N440C, and disrupted possible H-bonds involving Y437:D4 S4-S5 and N440:D4-S6. MTSEA exposure in closed, fast-inactivated, or slow-inactivated states in most mutants had little-to-no effect. In I439C, MTSEA application in closed, fast-inactivated, and slow-inactivated states produced irreversible reduction in current, suggesting I439C accessibility to MTSEA in all three kinetic states. D1-S6 is important for Nav gating kinetics, stability of slow-inactivated state, structural contacts, and state-dependent positioning. However, prominent reconfiguration of D1-S6 may not occur in slow inactivation.
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Affiliation(s)
- Jonathan M Beard
- Department of Biological Sciences, Southeastern Louisiana University, Hammond, LA, USA.
| | - Penny E Shockett
- Department of Biological Sciences, Southeastern Louisiana University, Hammond, LA, USA.
| | - John P O'Reilly
- Department of Biological Sciences, Southeastern Louisiana University, Hammond, LA, USA.
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Kalina RS, Peigneur S, Zelepuga EA, Dmitrenok PS, Kvetkina AN, Kim NY, Leychenko EV, Tytgat J, Kozlovskaya EP, Monastyrnaya MM, Gladkikh IN. New Insights into the Type II Toxins from the Sea Anemone Heteractis crispa. Toxins (Basel) 2020; 12:E44. [PMID: 31936885 PMCID: PMC7020476 DOI: 10.3390/toxins12010044] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 01/07/2020] [Accepted: 01/08/2020] [Indexed: 12/23/2022] Open
Abstract
Toxins modulating NaV channels are the most abundant and studied peptide components of sea anemone venom. Three type-II toxins, δ-SHTX-Hcr1f (= RpII), RTX-III, and RTX-VI, were isolated from the sea anemone Heteractis crispa. RTX-VI has been found to be an unusual analog of RTX-III. The electrophysiological effects of Heteractis toxins on nine NaV subtypes were investigated for the first time. Heteractis toxins mainly affect the inactivation of the mammalian NaV channels expressed in the central nervous system (NaV1.1-NaV1.3, NaV1.6) as well as insect and arachnid channels (BgNaV1, VdNaV1). The absence of Arg13 in the RTX-VI structure does not prevent toxin binding with the channel but it has changed its pharmacological profile and potency. According to computer modeling data, the δ-SHTX-Hcr1f binds within the extracellular region of the rNaV1.2 voltage-sensing domain IV and pore-forming domain I through a network of strong interactions, and an additional fixation of the toxin at the channel binding site is carried out through the phospholipid environment. Our data suggest that Heteractis toxins could be used as molecular tools for NaV channel studies or insecticides rather than as pharmacological agents.
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Affiliation(s)
- Rimma S. Kalina
- G.B. Elyakov Pacific Institute of Bioorganic Chemistry, Far Eastern Branch of the Russian Academy of Science, 690022 Vladivostok, Russia; (E.A.Z.); (P.S.D.); (A.N.K.); (N.Y.K.); (E.V.L.); (E.P.K.); (M.M.M.)
| | - Steve Peigneur
- Toxicology and Pharmacology, University of Leuven (KU Leuven), Campus Gasthuisberg, O&N 2, Herestraat~49, P.O. Box 922, 3000 Leuven, Belgium
| | - Elena A. Zelepuga
- G.B. Elyakov Pacific Institute of Bioorganic Chemistry, Far Eastern Branch of the Russian Academy of Science, 690022 Vladivostok, Russia; (E.A.Z.); (P.S.D.); (A.N.K.); (N.Y.K.); (E.V.L.); (E.P.K.); (M.M.M.)
| | - Pavel S. Dmitrenok
- G.B. Elyakov Pacific Institute of Bioorganic Chemistry, Far Eastern Branch of the Russian Academy of Science, 690022 Vladivostok, Russia; (E.A.Z.); (P.S.D.); (A.N.K.); (N.Y.K.); (E.V.L.); (E.P.K.); (M.M.M.)
| | - Aleksandra N. Kvetkina
- G.B. Elyakov Pacific Institute of Bioorganic Chemistry, Far Eastern Branch of the Russian Academy of Science, 690022 Vladivostok, Russia; (E.A.Z.); (P.S.D.); (A.N.K.); (N.Y.K.); (E.V.L.); (E.P.K.); (M.M.M.)
| | - Natalia Y. Kim
- G.B. Elyakov Pacific Institute of Bioorganic Chemistry, Far Eastern Branch of the Russian Academy of Science, 690022 Vladivostok, Russia; (E.A.Z.); (P.S.D.); (A.N.K.); (N.Y.K.); (E.V.L.); (E.P.K.); (M.M.M.)
| | - Elena V. Leychenko
- G.B. Elyakov Pacific Institute of Bioorganic Chemistry, Far Eastern Branch of the Russian Academy of Science, 690022 Vladivostok, Russia; (E.A.Z.); (P.S.D.); (A.N.K.); (N.Y.K.); (E.V.L.); (E.P.K.); (M.M.M.)
| | - Jan Tytgat
- Toxicology and Pharmacology, University of Leuven (KU Leuven), Campus Gasthuisberg, O&N 2, Herestraat~49, P.O. Box 922, 3000 Leuven, Belgium
| | - Emma P. Kozlovskaya
- G.B. Elyakov Pacific Institute of Bioorganic Chemistry, Far Eastern Branch of the Russian Academy of Science, 690022 Vladivostok, Russia; (E.A.Z.); (P.S.D.); (A.N.K.); (N.Y.K.); (E.V.L.); (E.P.K.); (M.M.M.)
| | - Margarita M. Monastyrnaya
- G.B. Elyakov Pacific Institute of Bioorganic Chemistry, Far Eastern Branch of the Russian Academy of Science, 690022 Vladivostok, Russia; (E.A.Z.); (P.S.D.); (A.N.K.); (N.Y.K.); (E.V.L.); (E.P.K.); (M.M.M.)
| | - Irina N. Gladkikh
- G.B. Elyakov Pacific Institute of Bioorganic Chemistry, Far Eastern Branch of the Russian Academy of Science, 690022 Vladivostok, Russia; (E.A.Z.); (P.S.D.); (A.N.K.); (N.Y.K.); (E.V.L.); (E.P.K.); (M.M.M.)
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Elia N, Palmio J, Castañeda MS, Shieh PB, Quinonez M, Suominen T, Hanna MG, Männikkö R, Udd B, Cannon SC. Myasthenic congenital myopathy from recessive mutations at a single residue in Na V1.4. Neurology 2019; 92:e1405-e1415. [PMID: 30824560 PMCID: PMC6453767 DOI: 10.1212/wnl.0000000000007185] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 11/04/2018] [Indexed: 01/12/2023] Open
Abstract
OBJECTIVE To identify the genetic and physiologic basis for recessive myasthenic congenital myopathy in 2 families, suggestive of a channelopathy involving the sodium channel gene, SCN4A. METHODS A combination of whole exome sequencing and targeted mutation analysis, followed by voltage-clamp studies of mutant sodium channels expressed in fibroblasts (HEK cells) and Xenopus oocytes. RESULTS Missense mutations of the same residue in the skeletal muscle sodium channel, R1460 of NaV1.4, were identified in a family and a single patient of Finnish origin (p.R1460Q) and a proband in the United States (p.R1460W). Congenital hypotonia, breathing difficulties, bulbar weakness, and fatigability had recessive inheritance (homozygous p.R1460W or compound heterozygous p.R1460Q and p.R1059X), whereas carriers were either asymptomatic (p.R1460W) or had myotonia (p.R1460Q). Sodium currents conducted by mutant channels showed unusual mixed defects with both loss-of-function (reduced amplitude, hyperpolarized shift of inactivation) and gain-of-function (slower entry and faster recovery from inactivation) changes. CONCLUSIONS Novel mutations in families with myasthenic congenital myopathy have been identified at p.R1460 of the sodium channel. Recessive inheritance, with experimentally established loss-of-function, is a consistent feature of sodium channel based myasthenia, whereas the mixed gain of function for p.R1460 may also cause susceptibility to myotonia.
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Affiliation(s)
- Nathaniel Elia
- From the Departments of Physiology (N.E., M.Q., S.C.C.) and Neurology (P.B.S.), David Geffen School of Medicine at UCLA; Molecular and Cellular Integrative Physiology Program at UCLA (N.E., S.C.C.), Los Angeles, CA; Tampere Neuromuscular Center (J.P., T.S., B.U.), Tampere University and University Hospital, Finland; MRC Centre for Neuromuscular Diseases (M.S.C., M.G.H., R.M.), Department of Neuromuscular Disease, UCL Institute of Neurology, London, UK; Folkhälsan Genetic Institute (B.U.), Helsinki; and Neurology Department (B.U.), Vasa Central Hospital, Finland
| | - Johanna Palmio
- From the Departments of Physiology (N.E., M.Q., S.C.C.) and Neurology (P.B.S.), David Geffen School of Medicine at UCLA; Molecular and Cellular Integrative Physiology Program at UCLA (N.E., S.C.C.), Los Angeles, CA; Tampere Neuromuscular Center (J.P., T.S., B.U.), Tampere University and University Hospital, Finland; MRC Centre for Neuromuscular Diseases (M.S.C., M.G.H., R.M.), Department of Neuromuscular Disease, UCL Institute of Neurology, London, UK; Folkhälsan Genetic Institute (B.U.), Helsinki; and Neurology Department (B.U.), Vasa Central Hospital, Finland
| | - Marisol Sampedro Castañeda
- From the Departments of Physiology (N.E., M.Q., S.C.C.) and Neurology (P.B.S.), David Geffen School of Medicine at UCLA; Molecular and Cellular Integrative Physiology Program at UCLA (N.E., S.C.C.), Los Angeles, CA; Tampere Neuromuscular Center (J.P., T.S., B.U.), Tampere University and University Hospital, Finland; MRC Centre for Neuromuscular Diseases (M.S.C., M.G.H., R.M.), Department of Neuromuscular Disease, UCL Institute of Neurology, London, UK; Folkhälsan Genetic Institute (B.U.), Helsinki; and Neurology Department (B.U.), Vasa Central Hospital, Finland
| | - Perry B Shieh
- From the Departments of Physiology (N.E., M.Q., S.C.C.) and Neurology (P.B.S.), David Geffen School of Medicine at UCLA; Molecular and Cellular Integrative Physiology Program at UCLA (N.E., S.C.C.), Los Angeles, CA; Tampere Neuromuscular Center (J.P., T.S., B.U.), Tampere University and University Hospital, Finland; MRC Centre for Neuromuscular Diseases (M.S.C., M.G.H., R.M.), Department of Neuromuscular Disease, UCL Institute of Neurology, London, UK; Folkhälsan Genetic Institute (B.U.), Helsinki; and Neurology Department (B.U.), Vasa Central Hospital, Finland
| | - Marbella Quinonez
- From the Departments of Physiology (N.E., M.Q., S.C.C.) and Neurology (P.B.S.), David Geffen School of Medicine at UCLA; Molecular and Cellular Integrative Physiology Program at UCLA (N.E., S.C.C.), Los Angeles, CA; Tampere Neuromuscular Center (J.P., T.S., B.U.), Tampere University and University Hospital, Finland; MRC Centre for Neuromuscular Diseases (M.S.C., M.G.H., R.M.), Department of Neuromuscular Disease, UCL Institute of Neurology, London, UK; Folkhälsan Genetic Institute (B.U.), Helsinki; and Neurology Department (B.U.), Vasa Central Hospital, Finland
| | - Tiina Suominen
- From the Departments of Physiology (N.E., M.Q., S.C.C.) and Neurology (P.B.S.), David Geffen School of Medicine at UCLA; Molecular and Cellular Integrative Physiology Program at UCLA (N.E., S.C.C.), Los Angeles, CA; Tampere Neuromuscular Center (J.P., T.S., B.U.), Tampere University and University Hospital, Finland; MRC Centre for Neuromuscular Diseases (M.S.C., M.G.H., R.M.), Department of Neuromuscular Disease, UCL Institute of Neurology, London, UK; Folkhälsan Genetic Institute (B.U.), Helsinki; and Neurology Department (B.U.), Vasa Central Hospital, Finland
| | - Michael G Hanna
- From the Departments of Physiology (N.E., M.Q., S.C.C.) and Neurology (P.B.S.), David Geffen School of Medicine at UCLA; Molecular and Cellular Integrative Physiology Program at UCLA (N.E., S.C.C.), Los Angeles, CA; Tampere Neuromuscular Center (J.P., T.S., B.U.), Tampere University and University Hospital, Finland; MRC Centre for Neuromuscular Diseases (M.S.C., M.G.H., R.M.), Department of Neuromuscular Disease, UCL Institute of Neurology, London, UK; Folkhälsan Genetic Institute (B.U.), Helsinki; and Neurology Department (B.U.), Vasa Central Hospital, Finland
| | - Roope Männikkö
- From the Departments of Physiology (N.E., M.Q., S.C.C.) and Neurology (P.B.S.), David Geffen School of Medicine at UCLA; Molecular and Cellular Integrative Physiology Program at UCLA (N.E., S.C.C.), Los Angeles, CA; Tampere Neuromuscular Center (J.P., T.S., B.U.), Tampere University and University Hospital, Finland; MRC Centre for Neuromuscular Diseases (M.S.C., M.G.H., R.M.), Department of Neuromuscular Disease, UCL Institute of Neurology, London, UK; Folkhälsan Genetic Institute (B.U.), Helsinki; and Neurology Department (B.U.), Vasa Central Hospital, Finland
| | - Bjarne Udd
- From the Departments of Physiology (N.E., M.Q., S.C.C.) and Neurology (P.B.S.), David Geffen School of Medicine at UCLA; Molecular and Cellular Integrative Physiology Program at UCLA (N.E., S.C.C.), Los Angeles, CA; Tampere Neuromuscular Center (J.P., T.S., B.U.), Tampere University and University Hospital, Finland; MRC Centre for Neuromuscular Diseases (M.S.C., M.G.H., R.M.), Department of Neuromuscular Disease, UCL Institute of Neurology, London, UK; Folkhälsan Genetic Institute (B.U.), Helsinki; and Neurology Department (B.U.), Vasa Central Hospital, Finland
| | - Stephen C Cannon
- From the Departments of Physiology (N.E., M.Q., S.C.C.) and Neurology (P.B.S.), David Geffen School of Medicine at UCLA; Molecular and Cellular Integrative Physiology Program at UCLA (N.E., S.C.C.), Los Angeles, CA; Tampere Neuromuscular Center (J.P., T.S., B.U.), Tampere University and University Hospital, Finland; MRC Centre for Neuromuscular Diseases (M.S.C., M.G.H., R.M.), Department of Neuromuscular Disease, UCL Institute of Neurology, London, UK; Folkhälsan Genetic Institute (B.U.), Helsinki; and Neurology Department (B.U.), Vasa Central Hospital, Finland.
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Pharmacogenetics of myotonic hNav1.4 sodium channel variants situated near the fast inactivation gate. Pharmacol Res 2019; 141:224-235. [DOI: 10.1016/j.phrs.2019.01.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 01/02/2019] [Accepted: 01/02/2019] [Indexed: 12/13/2022]
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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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