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Li Z, Wu Q, Yan N. A structural atlas of druggable sites on Na v channels. Channels (Austin) 2024; 18:2287832. [PMID: 38033122 PMCID: PMC10732651 DOI: 10.1080/19336950.2023.2287832] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Accepted: 11/20/2023] [Indexed: 12/02/2023] Open
Abstract
Voltage-gated sodium (Nav) channels govern membrane excitability by initiating and propagating action potentials. Consistent with their physiological significance, dysfunction, or mutations in these channels are associated with various channelopathies. Nav channels are thereby major targets for various clinical and investigational drugs. In addition, a large number of natural toxins, both small molecules and peptides, can bind to Nav channels and modulate their functions. Technological breakthrough in cryo-electron microscopy (cryo-EM) has enabled the determination of high-resolution structures of eukaryotic and eventually human Nav channels, alone or in complex with auxiliary subunits, toxins, and drugs. These studies have not only advanced our comprehension of channel architecture and working mechanisms but also afforded unprecedented clarity to the molecular basis for the binding and mechanism of action (MOA) of prototypical drugs and toxins. In this review, we will provide an overview of the recent advances in structural pharmacology of Nav channels, encompassing the structural map for ligand binding on Nav channels. These findings have established a vital groundwork for future drug development.
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Affiliation(s)
- Zhangqiang Li
- Beijing Frontier Research Center for Biological Structures, State Key Laboratory of Membrane Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Qiurong Wu
- Beijing Frontier Research Center for Biological Structures, State Key Laboratory of Membrane Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Nieng Yan
- Beijing Frontier Research Center for Biological Structures, State Key Laboratory of Membrane Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
- Shenzhen Medical Academy of Research and Translation, Shenzhen, Guangdong Province, China
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Wang X, Luo H, Peng X, Chen J. Spider and scorpion knottins targeting voltage-gated sodium ion channels in pain signaling. Biochem Pharmacol 2024; 227:116465. [PMID: 39102991 DOI: 10.1016/j.bcp.2024.116465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2024] [Revised: 07/30/2024] [Accepted: 08/02/2024] [Indexed: 08/07/2024]
Abstract
In sensory neurons that transmit pain signals, whether acute or chronic, voltage-gated sodium channels (VGSCs) are crucial for regulating excitability. NaV1.1, NaV1.3, NaV1.6, NaV1.7, NaV1.8, and NaV1.9 have been demonstrated and defined their functional roles in pain signaling based on their biophysical properties and distinct patterns of expression in each subtype of sensory neurons. Scorpions and spiders are traditional Chinese medicinal materials, belonging to the arachnid class. Most of the studied species of them have evolved venom peptides that exhibit a wide variety of knottins specifically targeting VGSCs with subtype selectivity and conformational specificity. This review provides an overview on the exquisite knottins from scorpion and spider venoms targeting pain-related NaV channels, describing the sequences and the structural features as well as molecular determinants that influence their selectivity on special subtype and at particular conformation, with an aim for the development of novel research tools on NaV channels and analgesics with minimal adverse effects.
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Affiliation(s)
- Xiting Wang
- College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, Hunan 410128, China
| | - Huan Luo
- College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, Hunan 410128, China
| | - Xiaozhen Peng
- School of Public Health & Laboratory Medicine, Hunan University of Medicine, Huaihua 418000, China.
| | - Jinjun Chen
- College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, Hunan 410128, China; Hunan Provincial Engineering Technology Research Center for Cell Mechanics and Function Analysis, Changsha 418000, China.
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3
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Pei S, Wang N, Mei Z, Zhangsun D, Craik DJ, McIntosh JM, Zhu X, Luo S. Conotoxins Targeting Voltage-Gated Sodium Ion Channels. Pharmacol Rev 2024; 76:828-845. [PMID: 38914468 PMCID: PMC11331937 DOI: 10.1124/pharmrev.123.000923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 06/17/2024] [Accepted: 06/18/2024] [Indexed: 06/26/2024] Open
Abstract
Voltage-gated sodium (NaV) channels are intimately involved in the generation and transmission of action potentials, and dysfunction of these channels may contribute to nervous system diseases, such as epilepsy, neuropathic pain, psychosis, autism, and cardiac arrhythmia. Many venom peptides selectively act on NaV channels. These include conotoxins, which are neurotoxins secreted by cone snails for prey capture or self-defense but which are also valuable pharmacological tools for the identification and/or treatment of human diseases. Typically, conotoxins contain two or three disulfide bonds, and these internal crossbraces contribute to conotoxins having compact, well defined structures and high stability. Of the conotoxins containing three disulfide bonds, some selectively target mammalian NaV channels and can block, stimulate, or modulate these channels. Such conotoxins have great potential to serve as pharmacological tools for studying the functions and characteristics of NaV channels or as drug leads for neurologic diseases related to NaV channels. Accordingly, discovering or designing conotoxins targeting NaV channels with high potency and selectivity is important. The amino acid sequences, disulfide bond connectivity, and three-dimensional structures are key factors that affect the biological activity of conotoxins, and targeted synthetic modifications of conotoxins can greatly improve their activity and selectivity. This review examines NaV channel-targeted conotoxins, focusing on their structures, activities, and designed modifications, with a view toward expanding their applications. SIGNIFICANCE STATEMENT: NaV channels are crucial in various neurologic diseases. Some conotoxins selectively target NaV channels, causing either blockade or activation, thus enabling their use as pharmacological tools for studying the channels' characteristics and functions. Conotoxins also have promising potential to be developed as drug leads. The disulfide bonds in these peptides are important for stabilizing their structures, thus leading to enhanced specificity and potency. Together, conotoxins targeting NaV channels have both immediate research value and promising future application prospects.
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Affiliation(s)
- Shengrong Pei
- Guangxi Key Laboratory of Special Biomedicine, School of Medicine, Guangxi University, Nanning, China (S.P., N.W., Z.M., D.Z., X.Z., S.L.); Key Laboratory of Tropical Biological Resources of Ministry of Education, Hainan University, Haikou, China (D.Z., S.L.); Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland, Australia (D.J.C.); Departments of Biology and Psychiatry, University of Utah, Salt Lake City, Utah (J.M.M.); and George E. Wahlen Veterans Affairs Medical Center, Salt Lake City, Utah (J.M.M.)
| | - Nan Wang
- Guangxi Key Laboratory of Special Biomedicine, School of Medicine, Guangxi University, Nanning, China (S.P., N.W., Z.M., D.Z., X.Z., S.L.); Key Laboratory of Tropical Biological Resources of Ministry of Education, Hainan University, Haikou, China (D.Z., S.L.); Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland, Australia (D.J.C.); Departments of Biology and Psychiatry, University of Utah, Salt Lake City, Utah (J.M.M.); and George E. Wahlen Veterans Affairs Medical Center, Salt Lake City, Utah (J.M.M.)
| | - Zaoli Mei
- Guangxi Key Laboratory of Special Biomedicine, School of Medicine, Guangxi University, Nanning, China (S.P., N.W., Z.M., D.Z., X.Z., S.L.); Key Laboratory of Tropical Biological Resources of Ministry of Education, Hainan University, Haikou, China (D.Z., S.L.); Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland, Australia (D.J.C.); Departments of Biology and Psychiatry, University of Utah, Salt Lake City, Utah (J.M.M.); and George E. Wahlen Veterans Affairs Medical Center, Salt Lake City, Utah (J.M.M.)
| | - Dongting Zhangsun
- Guangxi Key Laboratory of Special Biomedicine, School of Medicine, Guangxi University, Nanning, China (S.P., N.W., Z.M., D.Z., X.Z., S.L.); Key Laboratory of Tropical Biological Resources of Ministry of Education, Hainan University, Haikou, China (D.Z., S.L.); Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland, Australia (D.J.C.); Departments of Biology and Psychiatry, University of Utah, Salt Lake City, Utah (J.M.M.); and George E. Wahlen Veterans Affairs Medical Center, Salt Lake City, Utah (J.M.M.)
| | - David J Craik
- Guangxi Key Laboratory of Special Biomedicine, School of Medicine, Guangxi University, Nanning, China (S.P., N.W., Z.M., D.Z., X.Z., S.L.); Key Laboratory of Tropical Biological Resources of Ministry of Education, Hainan University, Haikou, China (D.Z., S.L.); Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland, Australia (D.J.C.); Departments of Biology and Psychiatry, University of Utah, Salt Lake City, Utah (J.M.M.); and George E. Wahlen Veterans Affairs Medical Center, Salt Lake City, Utah (J.M.M.)
| | - J Michael McIntosh
- Guangxi Key Laboratory of Special Biomedicine, School of Medicine, Guangxi University, Nanning, China (S.P., N.W., Z.M., D.Z., X.Z., S.L.); Key Laboratory of Tropical Biological Resources of Ministry of Education, Hainan University, Haikou, China (D.Z., S.L.); Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland, Australia (D.J.C.); Departments of Biology and Psychiatry, University of Utah, Salt Lake City, Utah (J.M.M.); and George E. Wahlen Veterans Affairs Medical Center, Salt Lake City, Utah (J.M.M.)
| | - Xiaopeng Zhu
- Guangxi Key Laboratory of Special Biomedicine, School of Medicine, Guangxi University, Nanning, China (S.P., N.W., Z.M., D.Z., X.Z., S.L.); Key Laboratory of Tropical Biological Resources of Ministry of Education, Hainan University, Haikou, China (D.Z., S.L.); Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland, Australia (D.J.C.); Departments of Biology and Psychiatry, University of Utah, Salt Lake City, Utah (J.M.M.); and George E. Wahlen Veterans Affairs Medical Center, Salt Lake City, Utah (J.M.M.)
| | - Sulan Luo
- Guangxi Key Laboratory of Special Biomedicine, School of Medicine, Guangxi University, Nanning, China (S.P., N.W., Z.M., D.Z., X.Z., S.L.); Key Laboratory of Tropical Biological Resources of Ministry of Education, Hainan University, Haikou, China (D.Z., S.L.); Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, Queensland, Australia (D.J.C.); Departments of Biology and Psychiatry, University of Utah, Salt Lake City, Utah (J.M.M.); and George E. Wahlen Veterans Affairs Medical Center, Salt Lake City, Utah (J.M.M.)
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Lu J, Dreyer I, Dickinson MS, Panzer S, Jaślan D, Navarro-Retamal C, Geiger D, Terpitz U, Becker D, Stroud RM, Marten I, Hedrich R. Vicia faba SV channel VfTPC1 is a hyperexcitable variant of plant vacuole Two Pore Channels. eLife 2023; 12:e86384. [PMID: 37991833 PMCID: PMC10665017 DOI: 10.7554/elife.86384] [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: 01/23/2023] [Accepted: 10/12/2023] [Indexed: 11/23/2023] Open
Abstract
To fire action-potential-like electrical signals, the vacuole membrane requires the two-pore channel TPC1, formerly called SV channel. The TPC1/SV channel functions as a depolarization-stimulated, non-selective cation channel that is inhibited by luminal Ca2+. In our search for species-dependent functional TPC1 channel variants with different luminal Ca2+ sensitivity, we found in total three acidic residues present in Ca2+ sensor sites 2 and 3 of the Ca2+-sensitive AtTPC1 channel from Arabidopsis thaliana that were neutral in its Vicia faba ortholog and also in those of many other Fabaceae. When expressed in the Arabidopsis AtTPC1-loss-of-function background, wild-type VfTPC1 was hypersensitive to vacuole depolarization and only weakly sensitive to blocking luminal Ca2+. When AtTPC1 was mutated for these VfTPC1-homologous polymorphic residues, two neutral substitutions in Ca2+ sensor site 3 alone were already sufficient for the Arabidopsis At-VfTPC1 channel mutant to gain VfTPC1-like voltage and luminal Ca2+ sensitivity that together rendered vacuoles hyperexcitable. Thus, natural TPC1 channel variants exist in plant families which may fine-tune vacuole excitability and adapt it to environmental settings of the particular ecological niche.
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Affiliation(s)
- Jinping Lu
- Julius-Maximilians-Universität (JMU), Biocenter, Department of Molecular Plant Physiology and BiophysicsWürzburgGermany
- School of Life Sciences, Zhengzhou UniversityZhengzhouChina
| | - Ingo Dreyer
- Universidad de Talca, Faculty of Engineering, Center of Bioinformatics, Simulation and ModelingTalcaChile
| | - Miles Sasha Dickinson
- University of California San Francisco, Department of Biochemistry and BiophysicsSan FranciscoUnited States
| | - Sabine Panzer
- Julius-Maximilians-Universität (JMU), Biocenter, Theodor-Boveri-Institute, Department of Biotechnology and BiophysicsWürzburgGermany
| | - Dawid Jaślan
- Julius-Maximilians-Universität (JMU), Biocenter, Department of Molecular Plant Physiology and BiophysicsWürzburgGermany
- Ludwig Maximilians-Universität, Faculty of Medicine, Walther Straub Institute of Pharmacology and ToxicologyMunichGermany
| | - Carlos Navarro-Retamal
- Universidad de Talca, Faculty of Engineering, Center of Bioinformatics, Simulation and ModelingTalcaChile
- Department of Cell Biology and Molecular Genetics, University of MarylandCollege ParkUnited States
| | - Dietmar Geiger
- Julius-Maximilians-Universität (JMU), Biocenter, Department of Molecular Plant Physiology and BiophysicsWürzburgGermany
| | - Ulrich Terpitz
- Julius-Maximilians-Universität (JMU), Biocenter, Theodor-Boveri-Institute, Department of Biotechnology and BiophysicsWürzburgGermany
| | - Dirk Becker
- Julius-Maximilians-Universität (JMU), Biocenter, Department of Molecular Plant Physiology and BiophysicsWürzburgGermany
| | - Robert M Stroud
- University of California San Francisco, Department of Biochemistry and BiophysicsSan FranciscoUnited States
| | - Irene Marten
- Julius-Maximilians-Universität (JMU), Biocenter, Department of Molecular Plant Physiology and BiophysicsWürzburgGermany
| | - Rainer Hedrich
- Julius-Maximilians-Universität (JMU), Biocenter, Department of Molecular Plant Physiology and BiophysicsWürzburgGermany
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Sato K, Momose-Sato Y. Optical recording of oscillatory activity in the absence of external Ca 2+ in the embryonic chick olfactory bulb. Neurosci Lett 2023; 809:137310. [PMID: 37225118 DOI: 10.1016/j.neulet.2023.137310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2023] [Revised: 05/11/2023] [Accepted: 05/18/2023] [Indexed: 05/26/2023]
Abstract
We applied 464/1020-site optical recording systems with a voltage-sensitive dye (NK2761) to the embryonic chick olfactory system and detected oscillatory activity in the olfactory bulb (OB) in the absence of synaptic transmission. In embryonic day 8-10 (E8-E10) chick olfactory nerve (N.I)-OB-forebrain preparations, the removal of Ca2+ from the external solution completely blocked the glutamatergic excitatory postsynaptic potential (EPSP) from the N.I to the OB as well as oscillations following the EPSP. However, a novel type of oscillatory activity was detected in the OB with the long-term perfusion of a Ca2+-free solution. The characteristics of oscillatory activity in the Ca2+-free solution differed from those in normal physiological solution. The present results suggest the existence of a neural communication system in the absence of synaptic transmission at the early stage of embryonic development.
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Affiliation(s)
- Katsushige Sato
- Department of Health and Nutrition Sciences, Komazawa Women's University Faculty of Human Health, Inagi-shi, Tokyo 206-8511, Japan.
| | - Yoko Momose-Sato
- Department of Nutrition and Dietetics, College of Nutrition, Kanto Gakuin University, Kanazawa-ku, Yokohama 236-8503, Japan
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6
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Structure of human Na V1.6 channel reveals Na + selectivity and pore blockade by 4,9-anhydro-tetrodotoxin. Nat Commun 2023; 14:1030. [PMID: 36823201 PMCID: PMC9950489 DOI: 10.1038/s41467-023-36766-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 02/15/2023] [Indexed: 02/25/2023] Open
Abstract
The sodium channel NaV1.6 is widely expressed in neurons of the central and peripheral nervous systems, which plays a critical role in regulating neuronal excitability. Dysfunction of NaV1.6 has been linked to epileptic encephalopathy, intellectual disability and movement disorders. Here we present cryo-EM structures of human NaV1.6/β1/β2 alone and complexed with a guanidinium neurotoxin 4,9-anhydro-tetrodotoxin (4,9-ah-TTX), revealing molecular mechanism of NaV1.6 inhibition by the blocker. The apo-form structure reveals two potential Na+ binding sites within the selectivity filter, suggesting a possible mechanism for Na+ selectivity and conductance. In the 4,9-ah-TTX bound structure, 4,9-ah-TTX binds to a pocket similar to the tetrodotoxin (TTX) binding site, which occupies the Na+ binding sites and completely blocks the channel. Molecular dynamics simulation results show that subtle conformational differences in the selectivity filter affect the affinity of TTX analogues. Taken together, our results provide important insights into NaV1.6 structure, ion conductance, and inhibition.
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Geffeney SL, Cordingley JA, Mitchell K, Hanifin CT. In Silico Analysis of Tetrodotoxin Binding in Voltage-Gated Sodium Ion Channels from Toxin-Resistant Animal Lineages. Mar Drugs 2022; 20:md20110723. [PMID: 36422001 PMCID: PMC9698786 DOI: 10.3390/md20110723] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2022] [Revised: 11/11/2022] [Accepted: 11/15/2022] [Indexed: 11/21/2022] Open
Abstract
Multiple animal species have evolved resistance to the neurotoxin tetrodotoxin (TTX) through changes in voltage-gated sodium ion channels (VGSCs). Amino acid substitutions in TTX-resistant lineages appear to be positionally convergent with changes in homologous residues associated with reductions in TTX block. We used homology modeling coupled with docking simulations to test whether positionally convergent substitutions generate functional convergence at the level of TTX–channel interactions. We found little evidence that amino acids at convergent positions generated similar patterns among TTX-resistant animal lineages across several metrics, including number of polar contacts, polar contact position, and estimates of binding energy. Though binding energy values calculated for TTX docking were reduced for some TTX-resistant channels, not all TTX-resistant channels and not all of our analyses returned reduced binding energy values for TTX-resistant channels. Our results do not support a simple model of toxin resistance where a reduced number of bonds between TTX and the channel protein prevents blocking. Rather models that incorporate flexibility and movement of the protein overall may better describe how homologous substitutions in the channel cause changes in TTX block.
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Jiang D, Zhang J, Xia Z. Structural Advances in Voltage-Gated Sodium Channels. Front Pharmacol 2022; 13:908867. [PMID: 35721169 PMCID: PMC9204039 DOI: 10.3389/fphar.2022.908867] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 05/23/2022] [Indexed: 11/17/2022] Open
Abstract
Voltage-gated sodium (NaV) channels are responsible for the rapid rising-phase of action potentials in excitable cells. Over 1,000 mutations in NaV channels are associated with human diseases including epilepsy, periodic paralysis, arrhythmias and pain disorders. Natural toxins and clinically-used small-molecule drugs bind to NaV channels and modulate their functions. Recent advances from cryo-electron microscopy (cryo-EM) structures of NaV channels reveal invaluable insights into the architecture, activation, fast inactivation, electromechanical coupling, ligand modulation and pharmacology of eukaryotic NaV channels. These structural analyses not only demonstrate molecular mechanisms for NaV channel structure and function, but also provide atomic level templates for rational development of potential subtype-selective therapeutics. In this review, we summarize recent structural advances of eukaryotic NaV channels, highlighting the structural features of eukaryotic NaV channels as well as distinct modulation mechanisms by a wide range of modulators from natural toxins to synthetic small-molecules.
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Affiliation(s)
- Daohua Jiang
- Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
- *Correspondence: Daohua Jiang,
| | - Jiangtao Zhang
- Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China
- Key Laboratory of Molecular Biophysics of MOE, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Zhanyi Xia
- Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
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Structure-guided unlocking of Na X reveals a non-selective tetrodotoxin-sensitive cation channel. Nat Commun 2022; 13:1416. [PMID: 35301303 PMCID: PMC8931054 DOI: 10.1038/s41467-022-28984-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 02/16/2022] [Indexed: 12/19/2022] Open
Abstract
Unlike classical voltage-gated sodium (NaV) channels, NaX has been characterized as a voltage-insensitive, tetrodotoxin-resistant, sodium (Na+)-activated channel involved in regulating Na+ homeostasis. However, NaX remains refractory to functional characterization in traditional heterologous systems. Here, to gain insight into its atypical physiology, we determine structures of the human NaX channel in complex with the auxiliary β3-subunit. NaX reveals structural alterations within the selectivity filter, voltage sensor-like domains, and pore module. We do not identify an extracellular Na+-sensor or any evidence for a Na+-based activation mechanism in NaX. Instead, the S6-gate remains closed, membrane lipids fill the central cavity, and the domain III-IV linker restricts S6-dilation. We use protein engineering to identify three pore-wetting mutations targeting the hydrophobic S6-gate that unlock a robust voltage-insensitive leak conductance. This constitutively active NaX-QTT channel construct is non-selective among monovalent cations, inhibited by extracellular calcium, and sensitive to classical NaV channel blockers, including tetrodotoxin. Our findings highlight a functional diversity across the NaV channel scaffold, reshape our understanding of NaX physiology, and provide a template to demystify recalcitrant ion channels.
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10
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Tao E, Corry B. Characterizing fenestration size in sodium channel subtypes and their accessibility to inhibitors. Biophys J 2022; 121:193-206. [PMID: 34958776 PMCID: PMC8790208 DOI: 10.1016/j.bpj.2021.12.025] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Revised: 12/07/2021] [Accepted: 12/16/2021] [Indexed: 01/21/2023] Open
Abstract
Voltage-gated sodium channels (Nav) underlie the electrical activity of nerve and muscle cells. Humans have nine different subtypes of these channels, which are the target of small-molecule inhibitors commonly used to treat a range of conditions. Structural studies have identified four lateral fenestrations within the Nav pore module that have been shown to influence Nav pore blocker access during resting-state inhibition. However, the structural differences among the nine subtypes are still unclear. In particular, the dimensions of the four individual fenestrations across the Nav subtypes and their differential accessibility to pore blockers is yet to be characterized. To address this, we applied classical molecular dynamics simulations to study the recently published structures of Nav1.1, Nav1.2, Nav1.4, Nav1.5, and Nav1.7. Although there is significant variability in the bottleneck sizes of the Nav fenestrations, the subtypes follow a common pattern, with wider DI-II and DIII-IV fenestrations, a more restricted DII-III fenestration, and the most restricted DI-IV fenestration. We further identify the key bottleneck residues in each fenestration and show that the motions of aromatic residue sidechains govern the bottleneck radii. Well-tempered metadynamics simulations of Nav1.4 and Nav1.5 in the presence of the pore blocker lidocaine also support the DI-II fenestration being the most likely access route for drugs. Our computational results provide a foundation for future in vitro experiments examining the route of drug access to sodium channels. Understanding the fenestrations and their accessibility to drugs is critical for future analyses of diseases mutations across different sodium channel subtypes, with the potential to inform pharmacological development of resting-state inhibitors and subtype-selective drug design.
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Affiliation(s)
- Elaine Tao
- Research School of Biology, Australian National University, Canberra, Australia
| | - Ben Corry
- Research School of Biology, Australian National University, Canberra, Australia.
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11
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Vallée C, Howlin B, Lewis R. Ion Selectivity in the ENaC/DEG Family: A Systematic Review with Supporting Analysis. Int J Mol Sci 2021; 22:ijms222010998. [PMID: 34681656 PMCID: PMC8536179 DOI: 10.3390/ijms222010998] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 10/01/2021] [Accepted: 10/05/2021] [Indexed: 12/16/2022] Open
Abstract
The Epithelial Sodium Channel/Degenerin (ENaC/DEG) family is a superfamily of sodium-selective channels that play diverse and important physiological roles in a wide variety of animal species. Despite their differences, they share a high homology in the pore region in which the ion discrimination takes place. Although ion selectivity has been studied for decades, the mechanisms underlying this selectivity for trimeric channels, and particularly for the ENaC/DEG family, are still poorly understood. This systematic review follows PRISMA guidelines and aims to determine the main components that govern ion selectivity in the ENaC/DEG family. In total, 27 papers from three online databases were included according to specific exclusion and inclusion criteria. It was found that the G/SxS selectivity filter (glycine/serine, non-conserved residue, serine) and other well conserved residues play a crucial role in ion selectivity. Depending on the ion type, residues with different properties are involved in ion permeability. For lithium against sodium, aromatic residues upstream of the selectivity filter seem to be important, whereas for sodium against potassium, negatively charged residues downstream of the selectivity filter seem to be important. This review provides new perspectives for further studies to unravel the mechanisms of ion selectivity.
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Affiliation(s)
- Cédric Vallée
- Leverhulme Quantum Biology Doctoral Training Centre, University of Surrey, Guildford GU2 5XH, UK; (C.V.); (B.H.)
- Department of Chemistry, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 7XH, UK
- School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford GU2 7AL, UK
| | - Brendan Howlin
- Leverhulme Quantum Biology Doctoral Training Centre, University of Surrey, Guildford GU2 5XH, UK; (C.V.); (B.H.)
- Department of Chemistry, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 7XH, UK
| | - Rebecca Lewis
- Leverhulme Quantum Biology Doctoral Training Centre, University of Surrey, Guildford GU2 5XH, UK; (C.V.); (B.H.)
- School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford GU2 7AL, UK
- Correspondence:
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Wang H, Duan W, Gao R, Li F, Yang L, Li W, Yin X, Wu S. Unique post-translational modifications diversify the sodium channels in peach aphid (Myzus persicae [Sulzer]). PEST MANAGEMENT SCIENCE 2021; 77:4521-4529. [PMID: 34041843 DOI: 10.1002/ps.6489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 05/19/2021] [Accepted: 05/27/2021] [Indexed: 06/12/2023]
Abstract
BACKGROUND Myzus persicae (Sulzer), a worldwide pest, has caused remarkable damage to agriculture. Among the various control methods, chemical control (especially pyrethroids) is most commonly used. The targets of pyrethroids are voltage-gated sodium channels (Nav s). Unlike those of other insects, all Nav s of aphids (including two genes), such as Myzus persicae, are unique. RESULTS In this study, three interlock patterns, I(918)-F(1014), L(918)-L(1014), and T(918)-F(1014), were found at sites 918 and 1014 in the sensitive Myzus persicae strain. Similar to that of other aphids, the Nav of Myzus persicae (MpNav ) consisted of two parts, that is MpNav -I and MpNav -II, which were embedded with an atypical 'DENS' ion selectivity filter and a conventional 'MFM' inactivation gate, respectively. MpNav had 11 alternative exons, including two mutually exclusive exons (k and l) and three exons (w, x, and t), which were located in domains I and III, respectively. In addition, various RNA editing events, A503T and V588A, appearing between the connection of domains I and II and the S3 of domain IV, respectively, had been described. CONCLUSION Overall, MpNav was characterized by unique post-translational regulation mode, 918 and 1014 interlocks, and unusually alternative exons. Our research provides a new perspective on the evolution and variation of insect Nav s. © 2021 Society of Chemical Industry.
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Affiliation(s)
- Hao Wang
- Hainan University, The Innovation Team of Research, Development, and Application of Key Technologies for Safe Production of Tropical Crops, Haikou, China
- College of Plant Protection, Henan Agricultural University, Zhengzhou, China
| | - WenBo Duan
- Hainan University, The Innovation Team of Research, Development, and Application of Key Technologies for Safe Production of Tropical Crops, Haikou, China
- College of Plant Protection, Henan Agricultural University, Zhengzhou, China
| | - Ruibo Gao
- Hainan University, The Innovation Team of Research, Development, and Application of Key Technologies for Safe Production of Tropical Crops, Haikou, China
| | - Fen Li
- Hainan University, The Innovation Team of Research, Development, and Application of Key Technologies for Safe Production of Tropical Crops, Haikou, China
| | - Lei Yang
- Hainan University, The Innovation Team of Research, Development, and Application of Key Technologies for Safe Production of Tropical Crops, Haikou, China
| | - WeiZheng Li
- College of Plant Protection, Henan Agricultural University, Zhengzhou, China
| | - XinMing Yin
- College of Plant Protection, Henan Agricultural University, Zhengzhou, China
| | - ShaoYing Wu
- Hainan University, The Innovation Team of Research, Development, and Application of Key Technologies for Safe Production of Tropical Crops, Haikou, China
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Zhorov BS. Possible Mechanism of Ion Selectivity in Eukaryotic Voltage-Gated Sodium Channels. J Phys Chem B 2021; 125:2074-2088. [DOI: 10.1021/acs.jpcb.0c11181] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Boris S. Zhorov
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario L8K 4K1, Canada
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg 194223, Russian Federation
- Almazov National Medical Research Centre, St. Petersburg 197341, Russian Federation
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14
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The Potential Role of Lithium as an Antiviral Agent against SARS-CoV-2 via Membrane Depolarization: Review and Hypothesis. Sci Pharm 2021. [DOI: 10.3390/scipharm89010011] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Studies on potential treatments of Coronavirus Disease 2019 (COVID-19) are important to improve the global situation in the face of the pandemic. This review proposes lithium as a potential drug to treat COVID-19. Our hypothesis states that lithium can suppress NOD-like receptor family pyrin domain containing-3 (NLRP3) inflammasome activity, inhibit cell death, and exhibit immunomodulation via membrane depolarization. Our hypothesis was formulated after finding consistent correlations between these actions and membrane depolarization induced by lithium. Eventually, lithium could serve to mitigate the NLRP3-mediated cytokine storm, which is allegedly reported to be the inciting event of a series of retrogressive events associated with mortality from COVID-19. It could also inhibit cell death and modulate the immune system to attenuate its release, clear the virus from the body, and interrupt the cycle of immune-system dysregulation. Therefore, these effects are presumed to improve the morbidity and mortality of COVID-19 patients. As the numbers of COVID-19 cases and deaths continue to rise exponentially without a clear consensus on potential therapeutic agents, urgent conduction of preclinical and clinical studies to prove the efficacy and safety of lithium is reasonable.
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15
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Pratt SJP, Hernández-Ochoa E, Martin SS. Calcium signaling: breast cancer's approach to manipulation of cellular circuitry. Biophys Rev 2020; 12:1343-1359. [PMID: 33569087 PMCID: PMC7755621 DOI: 10.1007/s12551-020-00771-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 10/29/2020] [Indexed: 12/11/2022] Open
Abstract
Calcium is a versatile element that participates in cell signaling for a wide range of cell processes such as death, cell cycle, division, migration, invasion, metabolism, differentiation, autophagy, transcription, and others. Specificity of calcium in each of these processes is achieved through modulation of intracellular calcium concentrations by changing the characteristics (amplitude/frequency modulation) or location (spatial modulation) of the signal. Breast cancer utilizes calcium signaling as an advantage for survival and progression. This review integrates evidence showing that increases in expression of calcium channels, GPCRs, pumps, effectors, and enzymes, as well as resulting intracellular calcium signals, lead to high calcium and/or an elevated calcium- mobilizing capacity necessary for malignant functions such as migratory, invasive, proliferative, tumorigenic, or metastatic capacities.
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Affiliation(s)
- Stephen J P Pratt
- Program in Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD USA.,Department of Physiology, University of Maryland School of Medicine, Baltimore, MD USA.,Marlene and Stewart Greenebaum NCI Comprehensive Cancer Center, University of Maryland School of Medicine, 655 W. Baltimore Street, Bressler Research Building, Rm 10-020 D, Baltimore, MD 21201 USA
| | - Erick Hernández-Ochoa
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD USA
| | - Stuart S Martin
- Program in Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD USA.,Department of Physiology, University of Maryland School of Medicine, Baltimore, MD USA.,Marlene and Stewart Greenebaum NCI Comprehensive Cancer Center, University of Maryland School of Medicine, 655 W. Baltimore Street, Bressler Research Building, Rm 10-020 D, Baltimore, MD 21201 USA
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16
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Malécot CO. Low voltage-activated channels in rat pulmonary vein cardiomyocytes: coexistence of a non-selective cationic channel and of T-type Ca channels. Pflugers Arch 2020; 472:1019-1029. [PMID: 32556635 DOI: 10.1007/s00424-020-02413-1] [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: 02/05/2020] [Revised: 05/27/2020] [Accepted: 05/29/2020] [Indexed: 10/24/2022]
Abstract
In rat pulmonary vein (PV) cardiomyocytes (CM), norepinephrine (NE) induces an automatic activity consisting of bursts of slow action potentials which depend on Ca2+ (upstroke) and Na+ (inter-burst) channels. Our objective was to characterize low voltage-activated (LVA) currents in rat PVCM susceptible to trigger this activity. Whole-cell ICa (5 mM Ca2+) was recorded from - 100 mV with classical Na+- and K+-free solutions. A fast LVA ICa (FLVA-ICa), present in ≈ 56% of PVCM between ~ - 50 to - 20 mV, was blocked by 10 μM TTX and markedly increased by addition of NaCl (1 or 3 mM) or KCl (5 or 10 mM). Permeability ratios P'Ca/PNa and P'Ca/PK calculated for bi-ionic conditions were respectively 2.25 ± 0.51 and 1.88 ± 0.25, and not different from a value of 2. FLVA-ICa was increased by 10 μM NE and 300 nM BayK8644, decreased by 5 μM nifedipine but not blocked by ranolazine (10 μM). NiCl2 (40 μM) and TTA-A2 (10 or 100 nM) increased FLVA-ICa. Similar results were obtained in left atrial (LA) CM. Neither Ba2+ nor Sr2+ alone could permeate the FLVA channel or block Ca2+ influx but revealed a large slower activating and inactivating LVA Ca2+ current (SLVA-ICa), present in 10 out of 80 PVCM, absent in LACM, and partially inhibited by 100 nM TTA-A2. Therefore, the ionic channel underlying FLVA-ICa is likely a fast voltage-gated non-selective channel with a dihydropyridine binding site. SLVA-ICa might correspond to Ca2+ influx through Cav3.x channels and contribute to triggering NE-induced automatic activity in the PV myocardial sleeve.
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Affiliation(s)
- Claire O Malécot
- Centre National de la Recherche Scientifique and Laboratoire Signalisation et Transports Ioniques Membranaires EA 7349, Université de Tours, Université de Poitiers, Parc de Grandmont, 37200, Tours, France.
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17
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Reimann HM, Niendorf T. The (Un)Conscious Mouse as a Model for Human Brain Functions: Key Principles of Anesthesia and Their Impact on Translational Neuroimaging. Front Syst Neurosci 2020; 14:8. [PMID: 32508601 PMCID: PMC7248373 DOI: 10.3389/fnsys.2020.00008] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 01/27/2020] [Indexed: 12/11/2022] Open
Abstract
In recent years, technical and procedural advances have brought functional magnetic resonance imaging (fMRI) to the field of murine neuroscience. Due to its unique capacity to measure functional activity non-invasively, across the entire brain, fMRI allows for the direct comparison of large-scale murine and human brain functions. This opens an avenue for bidirectional translational strategies to address fundamental questions ranging from neurological disorders to the nature of consciousness. The key challenges of murine fMRI are: (1) to generate and maintain functional brain states that approximate those of calm and relaxed human volunteers, while (2) preserving neurovascular coupling and physiological baseline conditions. Low-dose anesthetic protocols are commonly applied in murine functional brain studies to prevent stress and facilitate a calm and relaxed condition among animals. Yet, current mono-anesthesia has been shown to impair neural transmission and hemodynamic integrity. By linking the current state of murine electrophysiology, Ca2+ imaging and fMRI of anesthetic effects to findings from human studies, this systematic review proposes general principles to design, apply and monitor anesthetic protocols in a more sophisticated way. The further development of balanced multimodal anesthesia, combining two or more drugs with complementary modes of action helps to shape and maintain specific brain states and relevant aspects of murine physiology. Functional connectivity and its dynamic repertoire as assessed by fMRI can be used to make inferences about cortical states and provide additional information about whole-brain functional dynamics. Based on this, a simple and comprehensive functional neurosignature pattern can be determined for use in defining brain states and anesthetic depth in rest and in response to stimuli. Such a signature can be evaluated and shared between labs to indicate the brain state of a mouse during experiments, an important step toward translating findings across species.
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Affiliation(s)
- Henning M. Reimann
- Berlin Ultrahigh Field Facility (B.U.F.F.), Max-Delbrück Center for Molecular Medicine, Helmholtz Association of German Research Centers (HZ), Berlin, Germany
| | - Thoralf Niendorf
- Berlin Ultrahigh Field Facility (B.U.F.F.), Max-Delbrück Center for Molecular Medicine, Helmholtz Association of German Research Centers (HZ), Berlin, Germany
- Experimental and Clinical Research Center, A Joint Cooperation Between the Charité Medical Faculty and the Max-Delbrück Center for Molecular Medicine, Berlin, Germany
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18
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Silva JJ, Scott JG. Conservation of the voltage-sensitive sodium channel protein within the Insecta. INSECT MOLECULAR BIOLOGY 2020; 29:9-18. [PMID: 31206812 DOI: 10.1111/imb.12605] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2019] [Revised: 06/04/2019] [Accepted: 06/10/2019] [Indexed: 06/09/2023]
Abstract
The voltage-sensitive sodium channel (VSSC) is essential for the generation and propagation of action potentials. VSSC kinetics can be modified by producing different splice variants. The functionality of VSSC depends on features such as the voltage sensors, the selectivity filter and the inactivation loop. Mutations in Vssc conferring resistance to pyrethroid insecticides are known as knockdown resistance (kdr). We analysed the conservation of VSSC in both a broad scope and a narrow scope by three approaches: (1) we compared conservation of sequences and of differential exon use across orders of the Insecta; (2) we determined which kdr mutations were possible with a single nucleotide mutation in nine populations of Aedes aegypti; and (3) we examined the individual VSSC variation that exists within a population of Drosophila melanogaster. There is an increasing amount of transcript diversity possible from Diplura towards Diptera. The residues of the voltage sensors, selectivity filter and inactivation loop are highly conserved. The majority of exon sequences were >88.6% similar. Strain-specific differences in codon constraints exist for kdr mutations in nine strains of A. aegypti. Three Vssc mutations were found in one population of D. melanogaster. This study shows that, overall, Vssc is highly conserved across Insecta and within a population of an insect, but that important differences do exist.
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Affiliation(s)
- Juan J Silva
- Department of Entomology, Comstock Hall, Cornell University, Ithaca, NY, USA
| | - Jeffrey G Scott
- Department of Entomology, Comstock Hall, Cornell University, Ithaca, NY, USA
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19
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Jiang D, Shi H, Tonggu L, Gamal El-Din TM, Lenaeus MJ, Zhao Y, Yoshioka C, Zheng N, Catterall WA. Structure of the Cardiac Sodium Channel. Cell 2019; 180:122-134.e10. [PMID: 31866066 DOI: 10.1016/j.cell.2019.11.041] [Citation(s) in RCA: 198] [Impact Index Per Article: 39.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 11/18/2019] [Accepted: 11/27/2019] [Indexed: 12/19/2022]
Abstract
Voltage-gated sodium channel Nav1.5 generates cardiac action potentials and initiates the heartbeat. Here, we report structures of NaV1.5 at 3.2-3.5 Å resolution. NaV1.5 is distinguished from other sodium channels by a unique glycosyl moiety and loss of disulfide-bonding capability at the NaVβ subunit-interaction sites. The antiarrhythmic drug flecainide specifically targets the central cavity of the pore. The voltage sensors are partially activated, and the fast-inactivation gate is partially closed. Activation of the voltage sensor of Domain III allows binding of the isoleucine-phenylalanine-methionine (IFM) motif to the inactivation-gate receptor. Asp and Ala, in the selectivity motif DEKA, line the walls of the ion-selectivity filter, whereas Glu and Lys are in positions to accept and release Na+ ions via a charge-delocalization network. Arrhythmia mutation sites undergo large translocations during gating, providing a potential mechanism for pathogenic effects. Our results provide detailed insights into Nav1.5 structure, pharmacology, activation, inactivation, ion selectivity, and arrhythmias.
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Affiliation(s)
- Daohua Jiang
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA
| | - Hui Shi
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA; Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195, USA
| | - Lige Tonggu
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA
| | | | - Michael J Lenaeus
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA; Division of General Internal Medicine, Department of Medicine, University of Washington, Seattle, WA 98195, USA
| | - Yan Zhao
- Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Craig Yoshioka
- Vollum Institute, Oregon Health & Science University, Portland, OR 97239, 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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20
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Convergent and parallel evolution in a voltage-gated sodium channel underlies TTX-resistance in the Greater Blue-ringed Octopus: Hapalochlaena lunulata. Toxicon 2019; 170:77-84. [DOI: 10.1016/j.toxicon.2019.09.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 09/09/2019] [Accepted: 09/11/2019] [Indexed: 12/24/2022]
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21
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Contini D, Holstein GR, Art JJ. Synaptic cleft microenvironment influences potassium permeation and synaptic transmission in hair cells surrounded by calyx afferents in the turtle. J Physiol 2019; 598:853-889. [PMID: 31623011 DOI: 10.1113/jp278680] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 10/13/2019] [Indexed: 12/11/2022] Open
Abstract
KEY POINTS In central regions of vestibular semicircular canal epithelia, the [K+ ] in the synaptic cleft ([K+ ]c ) contributes to setting the hair cell and afferent membrane potentials; the potassium efflux from type I hair cells results from the interdependent gating of three conductances. Elevation of [K+ ]c occurs through a calcium-activated potassium conductance, GBK , and a low-voltage-activating delayed rectifier, GK(LV) , that activates upon elevation of [K+ ]c . Calcium influx that enables quantal transmission also activates IBK , an effect that can be blocked internally by BAPTA, and externally by a CaV 1.3 antagonist or iberiotoxin. Elevation of [K+ ]c or chelation of [Ca2+ ]c linearizes the GK(LV) steady-state I-V curve, suggesting that the outward rectification observed for GK(LV) may result largely from a potassium-sensitive relief of Ca2+ inactivation of the channel pore selectivity filter. Potassium sensitivity of hair cell and afferent conductances allows three modes of transmission: quantal, ion accumulation and resistive coupling to be multiplexed across the synapse. ABSTRACT In the vertebrate nervous system, ions accumulate in diffusion-limited synaptic clefts during ongoing activity. Such accumulation can be demonstrated at large appositions such as the hair cell-calyx afferent synapses present in central regions of the turtle vestibular semicircular canal epithelia. Type I hair cells influence discharge rates in their calyx afferents by modulating the potassium concentration in the synaptic cleft, [K+ ]c , which regulates potassium-sensitive conductances in both hair cell and afferent. Dual recordings from synaptic pairs have demonstrated that, despite a decreased driving force due to potassium accumulation, hair cell depolarization elicits sustained outward currents in the hair cell, and a maintained inward current in the afferent. We used kinetic and pharmacological dissection of the hair cell conductances to understand the interdependence of channel gating and permeation in the context of such restricted extracellular spaces. Hair cell depolarization leads to calcium influx and activation of a large calcium-activated potassium conductance, GBK , that can be blocked by agents that disrupt calcium influx or buffer the elevation of [Ca2+ ]i , as well as by the specific KCa 1.1 blocker iberiotoxin. Efflux of K+ through GBK can rapidly elevate [K+ ]c , which speeds the activation and slows the inactivation and deactivation of a second potassium conductance, GK(LV) . Elevation of [K+ ]c or chelation of [Ca2+ ]c linearizes the GK(LV) steady-state I-V curve, consistent with a K+ -dependent relief of Ca2+ inactivation of GK(LV) . As a result, this potassium-sensitive hair cell conductance pairs with the potassium-sensitive hyperpolarization-activated cyclic nucleotide-gated channel (HCN) conductance in the afferent and creates resistive coupling at the synaptic cleft.
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Affiliation(s)
- Donatella Contini
- Department of Anatomy & Cell Biology, University of Illinois College of Medicine, 808 S. Wood St, Chicago, IL, 60612, USA
| | - Gay R Holstein
- Neurology, Icahn School of Medicine at Mount Sinai, 1468 Madison Ave, New York, NY, 10029, USA
| | - Jonathan J Art
- Department of Anatomy & Cell Biology, University of Illinois College of Medicine, 808 S. Wood St, Chicago, IL, 60612, USA
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22
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Damjanovic A, Chen AY, Rosenberg RL, Roe DR, Wu X, Brooks BR. Protonation state of the selectivity filter of bacterial voltage‐gated sodium channels is modulated by ions. Proteins 2019; 88:527-539. [DOI: 10.1002/prot.25831] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 09/03/2019] [Accepted: 09/17/2019] [Indexed: 01/28/2023]
Affiliation(s)
- Ana Damjanovic
- Department of BiophysicsJohns Hopkins University Baltimore Maryland
| | - Ada Y. Chen
- Department of PhysicsJohns Hopkins University Baltimore Maryland
| | | | - Daniel R. Roe
- Laboratory of Computational Biology, National Heart, Lung and Blood InstituteNational Institutes of Health Bethesda Maryland
| | - Xiongwu Wu
- Laboratory of Computational Biology, National Heart, Lung and Blood InstituteNational Institutes of Health Bethesda Maryland
| | - Bernard R. Brooks
- Laboratory of Computational Biology, National Heart, Lung and Blood InstituteNational Institutes of Health Bethesda Maryland
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23
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Onkal R, Fraser SP, Djamgoz MB. Cationic Modulation of Voltage-Gated Sodium Channel (Nav1.5): Neonatal Versus Adult Splice Variants-1. Monovalent (H +) Ions. Bioelectricity 2019; 1:139-147. [PMID: 34471816 PMCID: PMC8370280 DOI: 10.1089/bioe.2019.0012] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Background: Voltage-gated sodium channels are functionally expressed in human carcinomas. In breast and colon cancers, the neonatal splice variant of Nav1.5 (nNav1.5) is dominant. This differs from the adult (aNav1.5) by several amino acids, including an outer charge reversal (residue-211): negatively charged aspartate (aNav1.5) versus positively charged lysine (nNav1.5). Thus, nNav1.5 and aNav1.5 may respond to extracellular charges differently. Materials and Methods: We used whole-cell patch-clamp recording to compare the electrophysiological effects of the monovalent cation hydrogen (H+) on nNav1.5 and aNav1.5 expressed stably in EBNA cells. Results: Increasing the H+ concentration (acidifying pH) reduced channel conductance and inhibited peak currents. Also, there was a positive shift in the voltage dependence of activation. These changes were significantly smaller for nNav1.5, compared with aNav1.5. Conclusions: nNav1.5 was more resistant to the suppressive effects of acidification compared with aNav1.5. Thus, nNav1.5 may have an advantage in promoting metastasis from the acidified tumor microenvironment.
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Affiliation(s)
- Rustem Onkal
- Department of Life Sciences, Neuroscience Solutions to Cancer Research Group, Imperial College London, London, United Kingdom
- Biotechnology Research Centre (BRC), North Cyprus International University, North Cyprus
| | - Scott P. Fraser
- Department of Life Sciences, Neuroscience Solutions to Cancer Research Group, Imperial College London, London, United Kingdom
| | - Mustafa B.A. Djamgoz
- Department of Life Sciences, Neuroscience Solutions to Cancer Research Group, Imperial College London, London, United Kingdom
- Biotechnology Research Centre (BRC), North Cyprus International University, North Cyprus
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van Alst TM, Wachsmuth L, Datunashvili M, Albers F, Just N, Budde T, Faber C. Anesthesia differentially modulates neuronal and vascular contributions to the BOLD signal. Neuroimage 2019; 195:89-103. [DOI: 10.1016/j.neuroimage.2019.03.057] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 03/06/2019] [Accepted: 03/25/2019] [Indexed: 11/27/2022] Open
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Zhang J, Mao W, Ren Y, Sun RN, Yan N, Gong H. Simulating the ion permeation and ion selection for a eukaryotic voltage-gated sodium channel Na VPaS. Protein Cell 2019. [PMID: 29532417 PMCID: PMC5966359 DOI: 10.1007/s13238-018-0522-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Affiliation(s)
- Juanrong Zhang
- MOE Key Laboratory of Bioinformatics, School of Life Sciences, Tsinghua University, Beijing, 100084, China
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing, 100084, China
| | - Wenzhi Mao
- MOE Key Laboratory of Bioinformatics, School of Life Sciences, Tsinghua University, Beijing, 100084, China
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing, 100084, China
| | - Yanhui Ren
- MOE Key Laboratory of Bioinformatics, School of Life Sciences, Tsinghua University, Beijing, 100084, China
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing, 100084, China
| | - Rui-Ning Sun
- MOE Key Laboratory of Bioinformatics, School of Life Sciences, Tsinghua University, Beijing, 100084, China
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing, 100084, China
| | - Nieng Yan
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing, 100084, China.
- State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China.
| | - Haipeng Gong
- MOE Key Laboratory of Bioinformatics, School of Life Sciences, Tsinghua University, Beijing, 100084, China.
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing, 100084, China.
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26
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Boiteux C, Flood E, Allen TW. Comparison of permeation mechanisms in sodium-selective ion channels. Neurosci Lett 2018; 700:3-8. [PMID: 29807068 DOI: 10.1016/j.neulet.2018.05.036] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Revised: 05/24/2018] [Accepted: 05/25/2018] [Indexed: 12/27/2022]
Abstract
Voltage-gated sodium channels are the molecular components of electrical signaling in the body, yet the molecular origins of Na+-selective transport remain obscured by diverse protein chemistries within this family of ion channels. In particular, bacterial and mammalian sodium channels are known to exhibit similar relative ion permeabilities for Na+ over K+ ions, despite their distinct signature EEEE and DEKA sequences. Atomic-level molecular dynamics simulations using high-resolution bacterial channel structures and mammalian channel models have begun to describe how these sequences lead to analogous high field strength ion binding sites that drive Na+ conduction. Similar complexes have also been identified in unrelated acid sensing ion channels involving glutamate and aspartate side chains that control their selectivity. These studies suggest the possibility of a common origin for Na+ selective binding and transport.
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Affiliation(s)
- Céline Boiteux
- School of Science, RMIT University, Melbourne, Australia
| | - Emelie Flood
- School of Science, RMIT University, Melbourne, Australia
| | - Toby W Allen
- School of Science, RMIT University, Melbourne, Australia.
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27
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Guardiani C, Fedorenko OA, Roberts SK, Khovanov IA. On the selectivity of the NaChBac channel: an integrated computational and experimental analysis of sodium and calcium permeation. Phys Chem Chem Phys 2018; 19:29840-29854. [PMID: 29090695 DOI: 10.1039/c7cp05928k] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Ion channel selectivity is essential for their function, yet the molecular basis of a channel's ability to select between ions is still rather controversial. In this work, using a combination of molecular dynamics simulations and electrophysiological current measurements we analyze the ability of the NaChBac channel to discriminate between calcium and sodium. Our simulations show that a single calcium ion can access the Selectivity Filter (SF) interacting so strongly with the glutamate ring so as to remain blocked inside. This is consistent with the tiny calcium currents recorded in our patch-clamp experiments. Two reasons explain this scenario. The first is the higher free energy of ion/SF binding of Ca2+ with respect to Na+. The second is the strong electrostatic repulsion exerted by the resident ion that turns back a second potentially incoming Ca2+, preventing the knock-on permeation mechanism. Finally, we analyzed the possibility of the Anomalous Mole Fraction Effect (AMFE), i.e. the ability of micromolar Ca2+ concentrations to block Na+ currents. Current measurements in Na+/Ca2+ mixed solutions excluded the AMFE, in agreement with metadynamics simulations showing the ability of a sodium ion to by-pass and partially displace the resident calcium. Our work supports a new scenario for Na+/Ca2+ selectivity in the bacterial sodium channel, challenging the traditional notion of an exclusion mechanism strictly confining Ca2+ ions outside the channel.
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Affiliation(s)
- Carlo Guardiani
- School of Engineering, University of Warwick, Coventry CV4 7AL, UK.
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28
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Ghovanloo MR, Peters CH, Ruben PC. Effects of acidosis on neuronal voltage-gated sodium channels: Nav1.1 and Nav1.3. Channels (Austin) 2018; 12:367-377. [PMID: 30362397 PMCID: PMC6284583 DOI: 10.1080/19336950.2018.1539611] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 10/15/2018] [Accepted: 10/17/2018] [Indexed: 01/14/2023] Open
Abstract
Voltage-gated sodium channels are key contributors to membrane excitability. These channels are expressed in a tissue-specific manner. Mutations and modulation of these channels underlie various physiological and pathophysiological manifestations. The effects of changes in extracellular pH on channel gating have been studied on several sodium channel subtypes. Among these, Nav1.5 is the most pH-sensitive channel, with Nav1.2 and Nav1.4 being mostly pH-resistant channels. However, pH effects have not been characterized on other sodium channel subtypes. In this study, we sought to determine whether Nav1.1 and Nav1.3 display resistance or sensitivity to changes in extracellular pH. These two sodium channel subtypes are predominantly found in inhibitory neurons. The expression of these channels highly depends on age and the developmental stage of neurons, with Nav1.3 being found mostly in neonatal neurons, and Nav1.1 being found in adult neurons. Our present results indicate that, during extracellular acidosis, both channels show a depolarization in the voltage-dependence of activation and moderate reduction in current density. Voltage-dependence of steady-state fast inactivation and recovery from fast inactivation were unchanged. We conclude that Nav1.1 and Nav1.3 have similar pH-sensitivities.
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Affiliation(s)
- Mohammad-Reza Ghovanloo
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, Canada
| | - Colin H. Peters
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, Canada
| | - Peter C. Ruben
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, Canada
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29
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Abstract
Voltage-gated sodium (Na+) channels are expressed in virtually all electrically excitable tissues and are essential for muscle contraction and the conduction of impulses within the peripheral and central nervous systems. Genetic disorders that disrupt the function of these channels produce an array of Na+ channelopathies resulting in neuronal impairment, chronic pain, neuromuscular pathologies, and cardiac arrhythmias. Because of their importance to the conduction of electrical signals, Na+ channels are the target of a wide variety of local anesthetic, antiarrhythmic, anticonvulsant, and antidepressant drugs. The voltage-gated family of Na+ channels is composed of α-subunits that encode for the voltage sensor domains and the Na+-selective permeation pore. In vivo, Na+ channel α-subunits are associated with one or more accessory β-subunits (β1-β4) that regulate gating properties, trafficking, and cell-surface expression of the channels. The permeation pore of Na+ channels is divided in two parts: the outer mouth of the pore is the site of the ion selectivity filter, while the inner cytoplasmic pore serves as the channel activation gate. The cytoplasmic lining of the permeation pore is formed by the S6 segments that include highly conserved aromatic amino acids important for drug binding. These residues are believed to undergo voltage-dependent conformational changes that alter drug binding as the channels cycle through the closed, open, and inactivated states. The purpose of this chapter is to broadly review the mechanisms of Na+ channel gating and the models used to describe drug binding and Na+ channel inhibition.
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Affiliation(s)
- M E O'Leary
- Cooper Medical School of Rowan University, Camden, NJ, USA
| | - M Chahine
- CERVO Brain Research Center, Institut universitaire en santé mentale de Québec, Quebec City, QC, Canada.
- Department of Medicine, Université Laval, Quebec City, QC, Canada.
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30
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Peters CH, Ghovanloo MR, Gershome C, Ruben PC. pH Modulation of Voltage-Gated Sodium Channels. Handb Exp Pharmacol 2018; 246:147-160. [PMID: 29460150 DOI: 10.1007/164_2018_99] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Changes in blood and tissue pH accompany physiological and pathophysiological conditions including exercise, cardiac ischemia, ischemic stroke, and cocaine ingestion. These conditions are known to trigger the symptoms of electrical diseases in patients carrying sodium channel mutations. Protons cause a diverse set of changes to sodium channel gating, which generally lead to decreases in the amplitude of the transient sodium current and increases in the fraction of non-inactivating channels that pass persistent currents. These effects are shared with disease-causing mutants in neuronal, skeletal muscle, and cardiac tissue and may be compounded in mutants that impart greater proton sensitivity to sodium channels, suggesting a role of protons in triggering acute symptoms of electrical disease.In this chapter, we review the mechanisms of proton block of the sodium channel pore and a suggested mode of action by which protons alter channel gating. We discuss the available data on isoform specificity of proton effects and tissue level effects. Finally, we review the role that protons play in disease and our own recent studies on proton-sensitizing mutants in cardiac and skeletal muscle sodium channels.
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Affiliation(s)
- Colin H Peters
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - Mohammad-Reza Ghovanloo
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - Cynthia Gershome
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - Peter C Ruben
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada.
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31
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Kaufman IK, Fedorenko OA, Luchinsky DG, Gibby WA, Roberts SK, McClintock PV, Eisenberg RS. Ionic Coulomb blockade and anomalous mole fraction effect in the NaChBac bacterial ion channel and its charge-varied mutants. ACTA ACUST UNITED AC 2017. [DOI: 10.1051/epjnbp/2017003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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32
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Ahmed M, Jalily Hasani H, Ganesan A, Houghton M, Barakat K. Modeling the human Na v1.5 sodium channel: structural and mechanistic insights of ion permeation and drug blockade. Drug Des Devel Ther 2017; 11:2301-2324. [PMID: 28831242 PMCID: PMC5552146 DOI: 10.2147/dddt.s133944] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Abnormalities in the human Nav1.5 (hNav1.5) voltage-gated sodium ion channel (VGSC) are associated with a wide range of cardiac problems and diseases in humans. Current structural models of hNav1.5 are still far from complete and, consequently, their ability to study atomistic interactions of this channel is very limited. Here, we report a comprehensive atomistic model of the hNav1.5 ion channel, constructed using homology modeling technique and refined through long molecular dynamics simulations (680 ns) in the lipid membrane bilayer. Our model was comprehensively validated by using reported mutagenesis data, comparisons with previous models, and binding to a panel of known hNav1.5 blockers. The relatively long classical MD simulation was sufficient to observe a natural sodium permeation event across the channel's selectivity filters to reach the channel's central cavity, together with the identification of a unique role of the lysine residue. Electrostatic potential calculations revealed the existence of two potential binding sites for the sodium ion at the outer selectivity filters. To obtain further mechanistic insight into the permeation event from the central cavity to the intracellular region of the channel, we further employed "state-of-the-art" steered molecular dynamics (SMD) simulations. Our SMD simulations revealed two different pathways through which a sodium ion can be expelled from the channel. Further, the SMD simulations identified the key residues that are likely to control these processes. Finally, we discuss the potential binding modes of a panel of known hNav1.5 blockers to our structural model of hNav1.5. We believe that the data presented here will enhance our understanding of the structure-property relationships of the hNav1.5 ion channel and the underlying molecular mechanisms in sodium ion permeation and drug interactions. The results presented here could be useful for designing safer drugs that do not block the hNav1.5 channel.
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Affiliation(s)
| | | | | | - Michael Houghton
- Li Ka Shing Institute of Virology
- Li Ka Shing Applied Virology Institute
- Department of Medical Microbiology and Immunology, Katz Centre for Health Research, University of Alberta, Edmonton, AB, Canada
| | - Khaled Barakat
- Faculty of Pharmacy and Pharmaceutical Sciences
- Li Ka Shing Institute of Virology
- Li Ka Shing Applied Virology Institute
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33
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Li Y, Sun R, Liu H, Gong H. Molecular dynamics study of ion transport through an open model of voltage-gated sodium channel. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:879-887. [DOI: 10.1016/j.bbamem.2017.02.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Revised: 01/12/2017] [Accepted: 02/05/2017] [Indexed: 12/30/2022]
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Shen H, Zhou Q, Pan X, Li Z, Wu J, Yan N. Structure of a eukaryotic voltage-gated sodium channel at near-atomic resolution. Science 2017; 355:science.aal4326. [PMID: 28183995 DOI: 10.1126/science.aal4326] [Citation(s) in RCA: 292] [Impact Index Per Article: 41.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 01/31/2017] [Indexed: 01/09/2023]
Abstract
Voltage-gated sodium (Nav) channels are responsible for the initiation and propagation of action potentials. They are associated with a variety of channelopathies and are targeted by multiple pharmaceutical drugs and natural toxins. Here, we report the cryogenic electron microscopy structure of a putative Nav channel from American cockroach (designated NavPaS) at 3.8 angstrom resolution. The voltage-sensing domains (VSDs) of the four repeats exhibit distinct conformations. The entrance to the asymmetric selectivity filter vestibule is guarded by heavily glycosylated and disulfide bond-stabilized extracellular loops. On the cytoplasmic side, a conserved amino-terminal domain is placed below VSDI, and a carboxy-terminal domain binds to the III-IV linker. The structure of NavPaS establishes an important foundation for understanding function and disease mechanism of Nav and related voltage-gated calcium channels.
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Affiliation(s)
- Huaizong Shen
- State Key Laboratory of Membrane Biology, Tsinghua University, Beijing 100084, China.,Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing 100084, China
| | - Qiang Zhou
- State Key Laboratory of Membrane Biology, Tsinghua University, Beijing 100084, China.,Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing 100084, China.,Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Xiaojing Pan
- State Key Laboratory of Membrane Biology, Tsinghua University, Beijing 100084, China.,Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing 100084, China
| | - Zhangqiang Li
- State Key Laboratory of Membrane Biology, Tsinghua University, Beijing 100084, China.,Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing 100084, China.,Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Jianping Wu
- State Key Laboratory of Membrane Biology, Tsinghua University, Beijing 100084, China.,Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing 100084, China.,Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Nieng Yan
- State Key Laboratory of Membrane Biology, Tsinghua University, Beijing 100084, China. .,Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing 100084, China.,Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
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35
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Structure-based assessment of disease-related mutations in human voltage-gated sodium channels. Protein Cell 2017; 8:401-438. [PMID: 28150151 PMCID: PMC5445024 DOI: 10.1007/s13238-017-0372-z] [Citation(s) in RCA: 100] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 01/09/2017] [Indexed: 12/15/2022] Open
Abstract
Voltage-gated sodium (Nav) channels are essential for the rapid upstroke of action potentials and the propagation of electrical signals in nerves and muscles. Defects of Nav channels are associated with a variety of channelopathies. More than 1000 disease-related mutations have been identified in Nav channels, with Nav1.1 and Nav1.5 each harboring more than 400 mutations. Nav channels represent major targets for a wide array of neurotoxins and drugs. Atomic structures of Nav channels are required to understand their function and disease mechanisms. The recently determined atomic structure of the rabbit voltage-gated calcium (Cav) channel Cav1.1 provides a template for homology-based structural modeling of the evolutionarily related Nav channels. In this Resource article, we summarized all the reported disease-related mutations in human Nav channels, generated a homologous model of human Nav1.7, and structurally mapped disease-associated mutations. Before the determination of structures of human Nav channels, the analysis presented here serves as the base framework for mechanistic investigation of Nav channelopathies and for potential structure-based drug discovery.
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36
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Tu YC, Yang YC, Kuo CC. Modulation of NMDA channel gating by Ca 2+ and Cd 2+ binding to the external pore mouth. Sci Rep 2016; 6:37029. [PMID: 27848984 PMCID: PMC5111045 DOI: 10.1038/srep37029] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 10/24/2016] [Indexed: 01/14/2023] Open
Abstract
NMDA receptor channels are characterized by high Ca2+ permeability. It remains unclear whether extracellular Ca2+ could directly modulate channel gating and control Ca2+ influxes. We demonstrate a pore-blocking site external to the activation gate for extracellular Ca2+ and Cd2+, which has the same charge and radius as Ca2+ but is impermeable to the channel. The apparent affinity of Cd2+ or Ca2+ is higher toward the activated (a steady-state mixture of the open and desensitized, probably chiefly the latter) than the closed states. The blocking effect of Cd2+ is well correlated with the number of charges in the DRPEER motif at the external pore mouth, with coupling coefficients close to 1 in double mutant cycle analyses. The effect of Ca2+ and especially Cd2+ could be allosterically affected by T647A mutation located just inside the activation gate. A prominent "hook" also develops after wash-off of Cd2+ or Ca2+, suggesting faster unbinding rates of Cd2+ and Ca2+ with the mutation. We conclude that extracellular Ca2+ or Cd2+ directly binds to the DRPEER motif to modify NMDA channel activation (opening as well as desensitization), which seems to involve essential regional conformational changes centered at the bundle crossing point A652 (GluN1)/A651(GluN2).
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Affiliation(s)
- Ya-Chi Tu
- Department of Physiology, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Ya-Chin Yang
- Department of Biomedical Sciences,College of Medicine, Chang Gung University, Tao-Yuan, Taiwan.,Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan.,Neuroscience Research Center, Chang Gung Memorial Hospital, Linkou Medical Center, Tao-Yuan, Taiwan
| | - Chung-Chin Kuo
- Department of Physiology, National Taiwan University College of Medicine, Taipei, Taiwan.,Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan
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37
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Ahern CA, Payandeh J, Bosmans F, Chanda B. The hitchhiker's guide to the voltage-gated sodium channel galaxy. ACTA ACUST UNITED AC 2016; 147:1-24. [PMID: 26712848 PMCID: PMC4692491 DOI: 10.1085/jgp.201511492] [Citation(s) in RCA: 234] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Eukaryotic voltage-gated sodium (Nav) channels contribute to the rising phase of action potentials and served as an early muse for biophysicists laying the foundation for our current understanding of electrical signaling. Given their central role in electrical excitability, it is not surprising that (a) inherited mutations in genes encoding for Nav channels and their accessory subunits have been linked to excitability disorders in brain, muscle, and heart; and (b) Nav channels are targeted by various drugs and naturally occurring toxins. Although the overall architecture and behavior of these channels are likely to be similar to the more well-studied voltage-gated potassium channels, eukaryotic Nav channels lack structural and functional symmetry, a notable difference that has implications for gating and selectivity. Activation of voltage-sensing modules of the first three domains in Nav channels is sufficient to open the channel pore, whereas movement of the domain IV voltage sensor is correlated with inactivation. Also, structure–function studies of eukaryotic Nav channels show that a set of amino acids in the selectivity filter, referred to as DEKA locus, is essential for Na+ selectivity. Structures of prokaryotic Nav channels have also shed new light on mechanisms of drug block. These structures exhibit lateral fenestrations that are large enough to allow drugs or lipophilic molecules to gain access into the inner vestibule, suggesting that this might be the passage for drug entry into a closed channel. In this Review, we will synthesize our current understanding of Nav channel gating mechanisms, ion selectivity and permeation, and modulation by therapeutics and toxins in light of the new structures of the prokaryotic Nav channels that, for the time being, serve as structural models of their eukaryotic counterparts.
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Affiliation(s)
- Christopher A Ahern
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA 52242
| | - Jian Payandeh
- Department of Structural Biology, Genentech, Inc., South San Francisco, CA 94080
| | - Frank Bosmans
- Department of Physiology and Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, School of Medicine, Baltimore, MD 21205 Department of Physiology and Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, School of Medicine, Baltimore, MD 21205
| | - Baron Chanda
- Department of Neuroscience and Department of Biomolecular Chemistry, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705 Department of Neuroscience and Department of Biomolecular Chemistry, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705
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38
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Vien TN, DeCaen PG. Biophysical Adaptations of Prokaryotic Voltage-Gated Sodium Channels. CURRENT TOPICS IN MEMBRANES 2016; 78:39-64. [PMID: 27586280 DOI: 10.1016/bs.ctm.2015.12.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
This chapter describes the adaptive features found in voltage-gated sodium channels (NaVs) of prokaryotes and eukaryotes. These two families are distinct, having diverged early in evolutionary history but maintain a surprising degree of convergence in function. While prokaryotic NaVs are required for growth and motility, eukaryotic NaVs selectively conduct fast electrical currents for short- and long-range signaling across cell membranes in mammalian organs. Current interest in prokaryotic NaVs is stoked by their resolved high-resolution structures and functional features which are reminiscent of eukaryotic NaVs. In this chapter, comparisons between eukaryotic and prokaryotic NaVs are made to highlight the shared and unique aspects of ion selectivity, voltage sensitivity, and pharmacology. Examples of prokaryotic and eukaryotic NaV convergent evolution will be discussed within the context of their structural features.
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Affiliation(s)
- T N Vien
- Tufts University, Boston, MA, United States
| | - P G DeCaen
- Children's Hospital Boston, Boston, MA, United States; Harvard Medical School, Boston, MA, United States; Northwestern University, Chicago, IL, United States
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Li Y, Liu H, Xia M, Gong H. Lysine and the Na+/K+ Selectivity in Mammalian Voltage-Gated Sodium Channels. PLoS One 2016; 11:e0162413. [PMID: 27584582 PMCID: PMC5008630 DOI: 10.1371/journal.pone.0162413] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 08/22/2016] [Indexed: 12/28/2022] Open
Abstract
Voltage-gated sodium (Nav) channels are critical in the generation and transmission of neuronal signals in mammals. The crystal structures of several prokaryotic Nav channels determined in recent years inspire the mechanistic studies on their selection upon the permeable cations (especially between Na+ and K+ ions), a property that is proposed to be mainly determined by residues in the selectivity filter. However, the mechanism of cation selection in mammalian Nav channels lacks direct explanation at atomic level due to the difference in amino acid sequences between mammalian and prokaryotic Nav homologues, especially at the constriction site where the DEKA motif has been identified to determine the Na+/K+ selectivity in mammalian Nav channels but is completely absent in the prokaryotic counterparts. Among the DEKA residues, Lys is of the most importance since its mutation to Arg abolishes the Na+/K+ selectivity. In this work, we modeled the pore domain of mammalian Nav channels by mutating the four residues at the constriction site of a prokaryotic Nav channel (NavRh) to DEKA, and then mechanistically investigated the contribution of Lys in cation selection using molecular dynamics simulations. The DERA mutant was generated as a comparison to understand the loss of ion selectivity caused by the K-to-R mutation. Simulations and free energy calculations on the mutants indicate that Lys facilitates Na+/K+ selection by electrostatically repelling the cation to a highly Na+-selective location sandwiched by the carboxylate groups of Asp and Glu at the constriction site. In contrast, the electrostatic repulsion is substantially weakened when Lys is mutated to Arg, because of two intrinsic properties of the Arg side chain: the planar geometric design and the sparse charge distribution of the guanidine group.
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Affiliation(s)
- Yang Li
- MOE Key Laboratory of Bioinformatics, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Huihui Liu
- MOE Key Laboratory of Bioinformatics, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Mengdie Xia
- MOE Key Laboratory of Bioinformatics, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Haipeng Gong
- MOE Key Laboratory of Bioinformatics, School of Life Sciences, Tsinghua University, Beijing 100084, China
- * E-mail:
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40
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Boiteux C, Allen TW. Understanding Sodium Channel Function and Modulation Using Atomistic Simulations of Bacterial Channel Structures. CURRENT TOPICS IN MEMBRANES 2016; 78:145-82. [PMID: 27586284 DOI: 10.1016/bs.ctm.2016.07.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Sodium channels are chief proteins involved in electrical signaling in the nervous system, enabling critical functions like heartbeat and brain activity. New high-resolution X-ray structures for bacterial sodium channels have created an opportunity to see how these proteins operate at the molecular level. An important challenge to overcome is establishing relationships between the structures and functions of mammalian and bacterial channels. Bacterial sodium channels are known to exhibit the main structural features of their mammalian counterparts, as well as several key functional characteristics, including selective ion conduction, voltage-dependent gating, pore-based inactivation and modulation by local anesthetic, antiarrhythmic and antiepileptic drugs. Simulations have begun to shed light on each of these features in the past few years. Despite deviations in selectivity signatures for bacterial and mammalian channels, simulations have uncovered the nature of the multiion conduction mechanism associated with Na(+) binding to a high-field strength site established by charged glutamate side chains. Simulations demonstrated a surprising level of flexibility of the protein, showing that these side chains are active participants in the permeation process. They have also uncovered changes in protein structure, leading to asymmetrical collapses of the activation gate that have been proposed to correspond to inactivated structures. These observations offer the potential to examine the mechanisms of state-dependent drug activity, focusing on pore-blocking and pore-based slow inactivation in bacterial channels, without the complexities of inactivation on multiple timescales seen in eukaryotic channels. Simulations have provided molecular views of the interactions of drugs, consistent with sites predicted in mammalian channels, as well as a wealth of other sites as potential new drug targets. In this chapter, we survey the new insights into sodium channel function that have emerged from studies of simpler bacterial channels, which provide an excellent learning platform, and promising avenues for mechanistic discovery and pharmacological development.
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Affiliation(s)
- C Boiteux
- RMIT University, Melbourne, VIC, Australia
| | - T W Allen
- RMIT University, Melbourne, VIC, Australia; University of California Davis, Davis, CA, United States
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41
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DeMarco KR, Clancy CE. Cardiac Na Channels: Structure to Function. CURRENT TOPICS IN MEMBRANES 2016; 78:287-311. [PMID: 27586288 DOI: 10.1016/bs.ctm.2016.05.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Heart rhythms arise from electrical activity generated by precisely timed opening and closing of ion channels in individual cardiac myocytes. Opening of the primary cardiac voltage-gated sodium (NaV1.5) channel initiates cellular depolarization and the propagation of an electrical action potential that promotes coordinated contraction of the heart. The regularity of these contractile waves is critically important since it drives the primary function of the heart: to act as a pump that delivers blood to the brain and vital organs. When electrical activity goes awry during a cardiac arrhythmia, the pump does not function, the brain does not receive oxygenated blood, and death ensues. Perturbations to NaV1.5 may alter the structure, and hence the function, of the ion channel and are associated downstream with a wide variety of cardiac conduction pathologies, such as arrhythmias.
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Affiliation(s)
- K R DeMarco
- University of California, Davis, Davis, CA, United States
| | - C E Clancy
- University of California, Davis, Davis, CA, United States
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42
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Zhang HY, Xu Q, Li F, Tian PC, Wang YH, Xiong Y, Zhang YH, Wei DQ. Recent progresses of simulations on passive membrane permeations in China. MOLECULAR SIMULATION 2016. [DOI: 10.1080/08927022.2015.1135333] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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43
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Oakes V, Furini S, Domene C. Voltage-Gated Sodium Channels: Mechanistic Insights From Atomistic Molecular Dynamics Simulations. CURRENT TOPICS IN MEMBRANES 2016; 78:183-214. [PMID: 27586285 DOI: 10.1016/bs.ctm.2015.12.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The permeation of ions and other molecules across biological membranes is an inherent requirement of all cellular organisms. Ion channels, in particular, are responsible for the conduction of charged species, hence modulating the propagation of electrical signals. Despite the universal physiological implications of this property, the molecular functioning of ion channels remains ambiguous. The combination of atomistic structural data with computational methodologies, such as molecular dynamics (MD) simulations, is now considered routine to investigate structure-function relationships in biological systems. A fuller understanding of conduction, selectivity, and gating, therefore, is steadily emerging due to the applicability of these techniques to ion channels. However, because their structure is known at atomic resolution, studies have consistently been biased toward K(+) channels, thus the molecular determinants of ionic selectivity, activation, and drug blockage in Na(+) channels are often overlooked. The recent increase of available crystallographic data has eminently encouraged the investigation of voltage-gated sodium (NaV) channels via computational methods. Here, we present an overview of simulation studies that have contributed to our understanding of key principles that underlie ionic conduction and selectivity in Na(+) channels, in comparison to the K(+) channel analogs.
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Affiliation(s)
- V Oakes
- King's College London, London, United Kingdom
| | - S Furini
- University of Siena, Siena, Italy
| | - C Domene
- King's College London, London, United Kingdom; University of Oxford, Oxford, United Kingdom
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44
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Naylor CE, Bagnéris C, DeCaen PG, Sula A, Scaglione A, Clapham DE, Wallace BA. Molecular basis of ion permeability in a voltage-gated sodium channel. EMBO J 2016; 35:820-30. [PMID: 26873592 PMCID: PMC4972137 DOI: 10.15252/embj.201593285] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 01/18/2016] [Indexed: 12/20/2022] Open
Abstract
Voltage‐gated sodium channels are essential for electrical signalling across cell membranes. They exhibit strong selectivities for sodium ions over other cations, enabling the finely tuned cascade of events associated with action potentials. This paper describes the ion permeability characteristics and the crystal structure of a prokaryotic sodium channel, showing for the first time the detailed locations of sodium ions in the selectivity filter of a sodium channel. Electrostatic calculations based on the structure are consistent with the relative cation permeability ratios (Na+ ≈ Li+ ≫ K+, Ca2+, Mg2+) measured for these channels. In an E178D selectivity filter mutant constructed to have altered ion selectivities, the sodium ion binding site nearest the extracellular side is missing. Unlike potassium ions in potassium channels, the sodium ions in these channels appear to be hydrated and are associated with side chains of the selectivity filter residues, rather than polypeptide backbones.
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Affiliation(s)
- Claire E Naylor
- Institute of Structural and Molecular Biology, Birkbeck College University of London, London, UK
| | - Claire Bagnéris
- Institute of Structural and Molecular Biology, Birkbeck College University of London, London, UK
| | - Paul G DeCaen
- Department of Cardiology, Howard Hughes Medical Institute Boston Children's Hospital, Boston, MA, USA Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Altin Sula
- Institute of Structural and Molecular Biology, Birkbeck College University of London, London, UK
| | - Antonella Scaglione
- Department of Cardiology, Howard Hughes Medical Institute Boston Children's Hospital, Boston, MA, USA Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - David E Clapham
- Department of Cardiology, Howard Hughes Medical Institute Boston Children's Hospital, Boston, MA, USA Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - B A Wallace
- Institute of Structural and Molecular Biology, Birkbeck College University of London, London, UK
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45
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Ing C, Pomès R. Simulation Studies of Ion Permeation and Selectivity in Voltage-Gated Sodium Channels. CURRENT TOPICS IN MEMBRANES 2016; 78:215-60. [DOI: 10.1016/bs.ctm.2016.07.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
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46
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Convergent Evolution of Tetrodotoxin-Resistant Sodium Channels in Predators and Prey. CURRENT TOPICS IN MEMBRANES 2016; 78:87-113. [DOI: 10.1016/bs.ctm.2016.07.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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47
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Mahdavi S, Kuyucak S. Mechanism of Ion Permeation in Mammalian Voltage-Gated Sodium Channels. PLoS One 2015; 10:e0133000. [PMID: 26274802 PMCID: PMC4537306 DOI: 10.1371/journal.pone.0133000] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Accepted: 06/22/2015] [Indexed: 12/30/2022] Open
Abstract
Recent determination of the crystal structures of bacterial voltage-gated sodium (NaV) channels have raised hopes that modeling of the mammalian counterparts could soon be achieved. However, there are substantial differences between the pore domains of the bacterial and mammalian NaV channels, which necessitates careful validation of mammalian homology models constructed from the bacterial NaV structures. Such a validated homology model for the NaV1.4 channel was constructed recently using the extensive mutagenesis data available for binding of μ-conotoxins. Here we use this NaV1.4 model to study the ion permeation mechanism in mammalian NaV channels. Linking of the DEKA residues in the selectivity filter with residues in the neighboring domains is found to be important for keeping the permeation pathway open. Molecular dynamics simulations and potential of mean force calculations reveal that there is a binding site for a Na+ ion just inside the DEKA locus, and 1-2 Na+ ions can occupy the vestibule near the EEDD ring. These sites are separated by a low free energy barrier, suggesting that inward conduction occurs when a Na+ ion in the vestibule goes over the free energy barrier and pushes the Na+ ion in the filter to the intracellular cavity, consistent with the classical knock-on mechanism. The NaV1.4 model also provides a good description of the observed Na+/K+ selectivity.
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Affiliation(s)
- Somayeh Mahdavi
- School of Physics, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Serdar Kuyucak
- School of Physics, University of Sydney, Sydney, New South Wales 2006, Australia
- * E-mail:
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48
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Kwong K, Carr MJ. Voltage-gated sodium channels. Curr Opin Pharmacol 2015; 22:131-9. [PMID: 26043074 DOI: 10.1016/j.coph.2015.04.007] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Revised: 04/21/2015] [Accepted: 04/29/2015] [Indexed: 12/11/2022]
Abstract
Voltage-gated sodium channels play a key role in the transmission of sensory information about the status of organs in the periphery. Sensory fibers contain a heterogeneous yet specific distribution of voltage-gated sodium channel isoforms. Major efforts by industry and academic groups are underway to develop medicines that interrupt inappropriate signaling for a number of clinical indications by taking advantage of this specific distribution of channel isoforms. This review highlights recent advances in the study of human channelopathies, animal toxins and channel structure that may facilitate the development of selective voltage-gated sodium channel blockers.
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49
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Li Y, Gong H. Theoretical and simulation studies on voltage-gated sodium channels. Protein Cell 2015; 6:413-22. [PMID: 25894089 PMCID: PMC4444806 DOI: 10.1007/s13238-015-0152-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 03/05/2015] [Indexed: 12/19/2022] Open
Abstract
Voltage-gated sodium (Nav) channels are indispensable membrane elements for the generation and propagation of electric signals in excitable cells. The successes in the crystallographic studies on prokaryotic Nav channels in recent years greatly promote the mechanistic investigation of these proteins and their eukaryotic counterparts. In this paper, we mainly review the progress in computational studies, especially the simulation studies, on these proteins in the past years.
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Affiliation(s)
- Yang Li
- MOE Key Laboratory of Bioinformatics, School of Life Sciences, Tsinghua University, Beijing, 100084 China
| | - Haipeng Gong
- MOE Key Laboratory of Bioinformatics, School of Life Sciences, Tsinghua University, Beijing, 100084 China
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50
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Dudev T, Lim C. Ion selectivity strategies of sodium channel selectivity filters. Acc Chem Res 2014; 47:3580-7. [PMID: 25343535 DOI: 10.1021/ar5002878] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
CONSPECTUS: Sodium ion channels selectively transport Na(+) cations across the cell membrane. These integral parts of the cell machinery are implicated in regulating the cardiac, skeletal and smooth muscle contraction, nerve impulses, salt and water homeostasis, as well as pain and taste perception. Their malfunction often results in various channelopathies of the heart, brain, skeletal muscles, and lung; thus, sodium channels are key drug targets for various disorders including cardiac arrhythmias, heart attack, stroke, migraine, epilepsy, pain, cancer, and autoimmune disorders. The ability of sodium channels to discriminate the native Na(+) among other competing ions in the surrounding fluids is crucial for proper cellular functions. The selectivity filter (SF), the narrowest part of the channel's open pore, lined with amino acid residues that specifically interact with the permeating ion, plays a major role in determining Na(+) selectivity. Different sodium channels have different SFs, which vary in the symmetry, number, charge, arrangement, and chemical type of the metal-ligating groups and pore size: epithelial/degenerin/acid-sensing ion channels have generally trimeric SFs lined with three conserved neutral serines and/or backbone carbonyls; eukaryotic sodium channels have EKEE, EEKE, DKEA, and DEKA SFs with an invariant positively charged lysine from the second or third domain; and bacterial voltage-gated sodium (Nav) channels exhibit symmetrical EEEE SFs, reminiscent of eukaryotic voltage-gated calcium channels. How do these different sodium channel SFs achieve high selectivity for Na(+) over its key rivals, K(+) and Ca(2+)? What factors govern the metal competition in these SFs and which of these factors are exploited to achieve Na(+) selectivity in the different sodium channel SFs? The free energies for replacing K(+) or Ca(2+) bound inside different model SFs with Na(+), evaluated by a combination of density functional theory and continuum dielectric calculations, have shed light on these questions. The SFs of epithelial and eukaryotic Nav channels select Na(+) by providing an optimal number and ligating strength of metal ligands as well as a rigid pore whose size fits the cognate Na(+) ideally. On the other hand, the SFs of bacterial Nav channels select Na(+), as the protein matrix attenuates ion-protein interactions relative to ion-solvent interactions by enlarging the pore and allowing water to enter, so the ion interacts indirectly with the conserved glutamates via bridging water molecules. This shows how these various SFs have adapted to the specific physicochemical properties of the native ion, using different strategies to select Na(+) among its contenders.
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Affiliation(s)
- Todor Dudev
- Faculty of Chemistry and Pharmacy, Sofia University, Sofia 1164, Bulgaria
| | - Carmay Lim
- Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan
- Department of Chemistry, National Tsing Hua University, Hsinchu 300, Taiwan
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