1
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Espino CM, Nagaraja C, Ortiz S, Dayton JR, Murali AR, Ma Y, Mann EL, Garlapalli S, Wohlgemuth RP, Brashear SE, Smith LR, Wilkinson KA, Griffith TN. Differential encoding of mammalian proprioception by voltage-gated sodium channels. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.08.27.609982. [PMID: 39253497 PMCID: PMC11383322 DOI: 10.1101/2024.08.27.609982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 09/11/2024]
Abstract
Animals that require purposeful movement for survival are endowed with mechanosensory neurons called proprioceptors that provide essential sensory feedback from muscles and joints to spinal cord circuits, which modulates motor output. Despite the essential nature of proprioceptive signaling in daily life, the mechanisms governing proprioceptor activity are poorly understood. Here, we have identified distinct and nonredundant roles for two voltage-gated sodium channels (NaVs), NaV1.1 and NaV1.6, in mammalian proprioception. Deletion of NaV1.6 in somatosensory neurons (NaV1.6cKO mice) causes severe motor deficits accompanied by complete loss of proprioceptive transmission, which contrasts with our previous findings using similar mouse models to target NaV1.1 (NaV1.1cKO). In NaV1.6cKO animals, loss of proprioceptive feedback caused non-cell-autonomous impairments in proprioceptor end-organs and skeletal muscle that were absent in NaV1.1cKO mice. We attribute the differential contribution of NaV1.1 and NaV1.6 in proprioceptor function to distinct cellular localization patterns. Collectively, these data provide the first evidence that NaV subtypes uniquely shape neurotransmission within a somatosensory modality.
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Affiliation(s)
- Cyrrus M Espino
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, USA
| | - Chetan Nagaraja
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, USA
| | - Serena Ortiz
- Department of Biological Sciences, San José State University, San Jose, CA, USA
| | - Jacquelyn R Dayton
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, USA
| | - Akash R Murali
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, USA
- Undergraduate Program in Neurobiology, Physiology and Behavior, University of California, Davis, Davis, CA, USA
| | - Yanki Ma
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, USA
- Undergraduate Program in Neurobiology, Physiology and Behavior, University of California, Davis, Davis, CA, USA
| | - Emari L Mann
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, USA
- Postbaccalaureate Research Education Program at UC Davis, University of California, Davis, Davis, CA, USA
| | - Snigdha Garlapalli
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, USA
- Undergraduate Program in Psychology, University of California, Davis, Davis, CA, USA
| | - Ross P Wohlgemuth
- Department of Physiology, Neurobiology, and Behavior, University of California, Davis, Davis, CA, USA
| | - Sarah E Brashear
- Department of Physiology, Neurobiology, and Behavior, University of California, Davis, Davis, CA, USA
| | - Lucas R Smith
- Department of Physiology, Neurobiology, and Behavior, University of California, Davis, Davis, CA, USA
| | | | - Theanne N Griffith
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, USA
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2
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Shrivastava A, Kumar A, Aggarwal LM, Pradhan S, Choudhary S, Ashish A, Kashyap K, Mishra S. Evolution of Bioelectric Membrane Potentials: Implications in Cancer Pathogenesis and Therapeutic Strategies. J Membr Biol 2024:10.1007/s00232-024-00323-2. [PMID: 39183198 DOI: 10.1007/s00232-024-00323-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2024] [Accepted: 08/16/2024] [Indexed: 08/27/2024]
Abstract
Electrophysiology typically deals with the electrical properties of excitable cells like neurons and muscles. However, all other cells (non-excitable) also possess bioelectric membrane potentials for intracellular and extracellular communications. These membrane potentials are generated by different ions present in fluids available in and outside the cell, playing a vital role in communication and coordination between the cell and its organelles. Bioelectric membrane potential variations disturb cellular ionic homeostasis and are characteristic of many diseases, including cancers. A rapidly increasing interest has emerged in sorting out the electrophysiology of cancer cells. Compared to healthy cells, the distinct electrical properties exhibited by cancer cells offer a unique way of understanding cancer development, migration, and progression. Decoding the altered bioelectric signals influenced by fluctuating electric fields benefits understanding cancer more closely. While cancer research has predominantly focussed on genetic and molecular traits, the delicate area of electrophysiological characteristics has increasingly gained prominence. This review explores the historical exploration of electrophysiology in the context of cancer cells, shedding light on how alterations in bioelectric membrane potentials, mediated by ion channels and gap junctions, contribute to the pathophysiology of cancer.
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Affiliation(s)
- Anju Shrivastava
- Department of Physiology, Chhattisgarh Institute of Medical Sciences, Bilaspur, India.
| | - Amit Kumar
- Department of Anatomy, Chhattisgarh Institute of Medical Sciences, Bilaspur, India
| | - Lalit Mohan Aggarwal
- Radiotherapy and Radiation Medicine, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
| | - Satyajit Pradhan
- Radiation Oncology, Mahamana Pandit Madhan Mohan Malaviya Cancer Centre, Varanasi, India
| | - Sunil Choudhary
- Radiotherapy and Radiation Medicine, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
| | - Ashish Ashish
- Department of Anatomy, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
| | - Keshav Kashyap
- Department of Physiology, Chhattisgarh Institute of Medical Sciences, Bilaspur, India
| | - Shivani Mishra
- Department of Anatomy, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
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3
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Pozzi E, Terribile G, Cherchi L, Di Girolamo S, Sancini G, Alberti P. Ion Channel and Transporter Involvement in Chemotherapy-Induced Peripheral Neurotoxicity. Int J Mol Sci 2024; 25:6552. [PMID: 38928257 PMCID: PMC11203899 DOI: 10.3390/ijms25126552] [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: 04/21/2024] [Revised: 06/06/2024] [Accepted: 06/11/2024] [Indexed: 06/28/2024] Open
Abstract
The peripheral nervous system can encounter alterations due to exposure to some of the most commonly used anticancer drugs (platinum drugs, taxanes, vinca alkaloids, proteasome inhibitors, thalidomide), the so-called chemotherapy-induced peripheral neurotoxicity (CIPN). CIPN can be long-lasting or even permanent, and it is detrimental for the quality of life of cancer survivors, being associated with persistent disturbances such as sensory loss and neuropathic pain at limb extremities due to a mostly sensory axonal polyneuropathy/neuronopathy. In the state of the art, there is no efficacious preventive/curative treatment for this condition. Among the reasons for this unmet clinical and scientific need, there is an uncomplete knowledge of the pathogenetic mechanisms. Ion channels and transporters are pivotal elements in both the central and peripheral nervous system, and there is a growing body of literature suggesting that they might play a role in CIPN development. In this review, we first describe the biophysical properties of these targets and then report existing data for the involvement of ion channels and transporters in CIPN, thus paving the way for new approaches/druggable targets to cure and/or prevent CIPN.
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Affiliation(s)
- Eleonora Pozzi
- Experimental Neurology Unit, School of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy; (E.P.); (L.C.); (S.D.G.)
| | - Giulia Terribile
- Human Physiology Unit, School of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy; (G.T.); (G.S.)
| | - Laura Cherchi
- Experimental Neurology Unit, School of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy; (E.P.); (L.C.); (S.D.G.)
| | - Sara Di Girolamo
- Experimental Neurology Unit, School of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy; (E.P.); (L.C.); (S.D.G.)
| | - Giulio Sancini
- Human Physiology Unit, School of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy; (G.T.); (G.S.)
| | - Paola Alberti
- Experimental Neurology Unit, School of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy; (E.P.); (L.C.); (S.D.G.)
- Fondazione IRCCS San Gerardo dei Tintori, 20900 Monza, Italy
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4
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Waheed S, Ramzan K, Ahmad S, Khan MS, Wajid M, Ullah H, Umar A, Iqbal R, Ullah R, Bari A. Identification and In-Silico study of non-synonymous functional SNPs in the human SCN9A gene. PLoS One 2024; 19:e0297367. [PMID: 38394191 PMCID: PMC10889873 DOI: 10.1371/journal.pone.0297367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Accepted: 12/29/2023] [Indexed: 02/25/2024] Open
Abstract
Single nucleotide polymorphisms are the most common form of DNA alterations at the level of a single nucleotide in the genomic sequence. Genome-wide association studies (GWAS) were carried to identify potential risk genes or genomic regions by screening for SNPs associated with disease. Recent studies have shown that SCN9A comprises the NaV1.7 subunit, Na+ channels have a gene encoding of 1988 amino acids arranged into 4 domains, all with 6 transmembrane regions, and are mainly found in dorsal root ganglion (DRG) neurons and sympathetic ganglion neurons. Multiple forms of acute hypersensitivity conditions, such as primary erythermalgia, congenital analgesia, and paroxysmal pain syndrome have been linked to polymorphisms in the SCN9A gene. Under this study, we utilized a variety of computational tools to explore out nsSNPs that are potentially damaging to heath by modifying the structure or activity of the SCN9A protein. Over 14 potentially damaging and disease-causing nsSNPs (E1889D, L1802P, F1782V, D1778N, C1370Y, V1311M, Y1248H, F1237L, M936V, I929T, V877E, D743Y, C710W, D623H) were identified by a variety of algorithms, including SNPnexus, SNAP-2, PANTHER, PhD-SNP, SNP & GO, I-Mutant, and ConSurf. Homology modeling, structure validation, and protein-ligand interactions also were performed to confirm 5 notable substitutions (L1802P, F1782V, D1778N, V1311M, and M936V). Such nsSNPs may become the center of further studies into a variety of disorders brought by SCN9A dysfunction. Using in-silico strategies for assessing SCN9A genetic variations will aid in organizing large-scale investigations and developing targeted therapeutics for disorders linked to these variations.
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Affiliation(s)
- Sana Waheed
- Faculty of Life Science, Department of Zoology, University of Okara, Okara, Pakistan
| | - Kainat Ramzan
- Faculty of Life Science, Department of Biochemistry, University of Okara, Okara, Pakistan
| | - Sibtain Ahmad
- Faculty of Animal Husbandry, Institute of Animal and Dairy Sciences, University of Agriculture, Faisalabad, Pakistan
| | - Muhammad Saleem Khan
- Faculty of Life Science, Department of Zoology, University of Okara, Okara, Pakistan
| | - Muhammad Wajid
- Faculty of Life Science, Department of Zoology, University of Okara, Okara, Pakistan
| | - Hayat Ullah
- Department of Chemistry, University of Okara, Okara, Pakistan
| | - Ali Umar
- Faculty of Life Science, Department of Zoology, University of Okara, Okara, Pakistan
| | - Rashid Iqbal
- Faculty of Agriculture and Environment, Department of Agronomy, The Islamia University of Bahawalpur, Bahawalpur, Pakistan
| | - Riaz Ullah
- Department of Pharmacognosy College of Pharmacy King Saud University, Riyadh, Saudi Arabia
| | - Ahmed Bari
- Department of Pharmaceutical Chemistry, College of Pharmacy King Saud University, Riyadh, Saudi Arabia
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5
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Seneci L, Mikheyev AS. Sodium Channel β Subunits-An Additional Element in Animal Tetrodotoxin Resistance? Int J Mol Sci 2024; 25:1478. [PMID: 38338757 PMCID: PMC10855141 DOI: 10.3390/ijms25031478] [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: 10/30/2023] [Revised: 12/09/2023] [Accepted: 12/15/2023] [Indexed: 02/12/2024] Open
Abstract
Tetrodotoxin (TTX) is a neurotoxic molecule used by many animals for defense and/or predation, as well as an important biomedical tool. Its ubiquity as a defensive agent has led to repeated independent evolution of tetrodotoxin resistance in animals. TTX binds to voltage-gated sodium channels (VGSC) consisting of α and β subunits. Virtually all studies investigating the mechanisms behind TTX resistance have focused on the α subunit of voltage-gated sodium channels, where tetrodotoxin binds. However, the possibility of β subunits also contributing to tetrodotoxin resistance was never explored, though these subunits act in concert. In this study, we present preliminary evidence suggesting a potential role of β subunits in the evolution of TTX resistance. We gathered mRNA sequences for all β subunit types found in vertebrates across 12 species (three TTX-resistant and nine TTX-sensitive) and tested for signatures of positive selection with a maximum likelihood approach. Our results revealed several sites experiencing positive selection in TTX-resistant taxa, though none were exclusive to those species in subunit β1, which forms a complex with the main physiological target of TTX (VGSC Nav1.4). While experimental data validating these findings would be necessary, this work suggests that deeper investigation into β subunits as potential players in tetrodotoxin resistance may be worthwhile.
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Affiliation(s)
- Lorenzo Seneci
- Adaptive Biotoxicology Lab, School of the Environment, The University of Queensland, St Lucia, QLD 4067, Australia;
| | - Alexander S. Mikheyev
- Evolutionary Genomics Group, Research School of Biology, Australian National University, Canberra, ACT 0200, Australia
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6
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Das P, Mekonnen B, Alkhofash R, Ingle AV, Workman EB, Feather A, Zhang G, Chasen N, Liu P, Lechtreck KF. The Small Interactor of PKD2 protein promotes the assembly and ciliary entry of the Chlamydomonas PKD2-mastigoneme complexes. J Cell Sci 2024; 137:jcs261497. [PMID: 38063216 PMCID: PMC10846610 DOI: 10.1242/jcs.261497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Accepted: 12/04/2023] [Indexed: 01/13/2024] Open
Abstract
In Chlamydomonas, the channel polycystin 2 (PKD2) is primarily present in the distal region of cilia, where it is attached to the axoneme and mastigonemes, extracellular polymers of MST1. In a smaller proximal ciliary region that lacks mastigonemes, PKD2 is more mobile. We show that the PKD2 regions are established early during ciliogenesis and increase proportionally in length as cilia elongate. In chimeric zygotes, tagged PKD2 rapidly entered the proximal region of PKD2-deficient cilia, whereas the assembly of the distal region was hindered, suggesting that axonemal binding of PKD2 requires de novo assembly of cilia. We identified the protein Small Interactor of PKD2 (SIP), a PKD2-related, single-pass transmembrane protein, as part of the PKD2-mastigoneme complex. In sip mutants, stability and proteolytic processing of PKD2 in the cell body were reduced and PKD2-mastigoneme complexes were absent from the cilia. Like the pkd2 and mst1 mutants, sip mutant cells swam with reduced velocity. Cilia of the pkd2 mutant beat with an increased frequency but were less efficient in moving the cells, suggesting a structural role for the PKD2-SIP-mastigoneme complex in increasing the effective surface of Chlamydomonas cilia.
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Affiliation(s)
- Poulomi Das
- Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
| | - Betlehem Mekonnen
- Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
| | - Rama Alkhofash
- Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
| | - Abha V. Ingle
- Department of Computer Science, University of Georgia, Athens, GA 30602, USA
| | - E. Blair Workman
- Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
| | - Alec Feather
- Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
| | - Gui Zhang
- Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
| | - Nathan Chasen
- Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
| | - Peiwei Liu
- Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
| | - Karl F. Lechtreck
- Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
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7
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Janes ME, Kinlein A, Flajnik MF, Du Pasquier L, Ohta Y. Genomic view of the origins of cell-mediated immunity. Immunogenetics 2023; 75:479-493. [PMID: 37735270 PMCID: PMC11019866 DOI: 10.1007/s00251-023-01319-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Accepted: 08/10/2023] [Indexed: 09/23/2023]
Abstract
NKp30 is an activating natural killer cell receptor (NKR) with a single-exon variable (VJ)-type immunoglobulin superfamily (IgSF) domain. Such VJ-IgSF domains predate the emergence of the antigen receptors (immunoglobulin and T cell receptor), which possess the same domain but undergo gene rearrangement. NCR3, the gene encoding NKp30, is present in jawed vertebrates from sharks to mammals; thus, unlike most NKR that are highly divergent among vertebrate taxa, NKp30 is uniquely conserved. We previously hypothesized that an ancestral NCR3 gene was encoded in the proto-major histocompatibility complex (MHC), the region where many immune-related genes have accumulated. Herein, we searched in silico databases to identify NCR3 paralogues and examined their genomic locations. We found a paralogue, NCR3H, in many vertebrates but was lost in mammals. Additionally, we identified a set of voltage-gated sodium channel beta (SCNB) genes as NCR3-distantly-related genes. Like NCR3, both NCR3H and SCNB proteins contain a single VJ-IgSF domain followed by a transmembrane region. These genes map to MHC paralogous regions, originally described in an invertebrate, along with genes encoding cell adhesion molecules involved in NK cell recognition networks. Other genes having no obvious relationship to immunity also map to these paralogous regions. These gene complexes were traced to several invertebrates, suggesting that the foundation of these cellular networks emerged before the genome-wide duplications in early gnathostome history. Here, we propose that this ancestral region was involved in cell-mediated immunity prior to the emergence of adaptive immunity and that NCR3 piggybacked onto this primordial complex, heralding the emergence of vertebrate NK cell/T cells.
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Affiliation(s)
- Morgan E Janes
- Department of Microbiology and Immunology, University of Maryland, Baltimore, MD, 21201, USA
| | - Allison Kinlein
- Department of Microbiology and Immunology, University of Maryland, Baltimore, MD, 21201, USA
| | - Martin F Flajnik
- Department of Microbiology and Immunology, University of Maryland, Baltimore, MD, 21201, USA
| | - Louis Du Pasquier
- Department of Environmental Sciences, Zoology, University of Basel, Vesalgasse 1, 4051, Basel, Switzerland
| | - Yuko Ohta
- Department of Microbiology and Immunology, University of Maryland, Baltimore, MD, 21201, USA.
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8
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Malcolm JR, Sajjaboontawee N, Yerlikaya S, Plunkett-Jones C, Boxall PJ, Brackenbury WJ. Voltage-gated sodium channels, sodium transport and progression of solid tumours. CURRENT TOPICS IN MEMBRANES 2023; 92:71-98. [PMID: 38007270 DOI: 10.1016/bs.ctm.2023.09.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2023]
Abstract
Sodium (Na+) concentration in solid tumours of different origin is highly dysregulated, and this corresponds to the aberrant expression of Na+ transporters. In particular, the α subunits of voltage gated Na+ channels (VGSCs) raise intracellular Na+ concentration ([Na+]i) in malignant cells, which influences the progression of solid tumours, predominantly driving cancer cells towards a more aggressive and metastatic phenotype. Conversely, re-expression of VGSC β subunits in cancer cells can either enhance tumour progression or promote anti-tumourigenic properties. Metastasis is the leading cause of cancer-related mortality, highlighting an important area of research which urgently requires improved therapeutic interventions. Here, we review the extent to which VGSC subunits are dysregulated in solid tumours, and consider the implications of such dysregulation on solid tumour progression. We discuss current understanding of VGSC-dependent mechanisms underlying increased invasive and metastatic potential of solid tumours, and how the complex relationship between the tumour microenvironment (TME) and VGSC expression may further drive tumour progression, in part due to the interplay of infiltrating immune cells, cancer-associated fibroblasts (CAFs) and insufficient supply of oxygen (hypoxia). Finally, we explore past and present clinical trials that investigate utilising existing VGSC modulators as potential pharmacological options to support adjuvant chemotherapies to prevent cancer recurrence. Such research demonstrates an exciting opportunity to repurpose therapeutics in order to improve the disease-free survival of patients with aggressive solid tumours.
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Affiliation(s)
- Jodie R Malcolm
- Department of Biology, University of York, Heslington, York, United Kingdom
| | - Nattanan Sajjaboontawee
- Department of Biology, University of York, Heslington, York, United Kingdom; York Biomedical Research Institute, University of York, Heslington, York, United Kingdom
| | - Serife Yerlikaya
- Department of Biology, University of York, Heslington, York, United Kingdom; Istanbul Medipol University, Research Institute for Health Sciences and Technologies, Istanbul, Turkey
| | | | - Peter J Boxall
- Department of Biology, University of York, Heslington, York, United Kingdom; York and Scarborough Teaching Hospitals NHS Foundation Trust, York, United Kingdom
| | - William J Brackenbury
- Department of Biology, University of York, Heslington, York, United Kingdom; York Biomedical Research Institute, University of York, Heslington, York, United Kingdom.
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9
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Eltokhi A, Catterall WA, Gamal El-Din TM. Cell-cycle arrest at the G1/S boundary enhances transient voltage-gated ion channel expression in human and insect cells. CELL REPORTS METHODS 2023; 3:100559. [PMID: 37751687 PMCID: PMC10545908 DOI: 10.1016/j.crmeth.2023.100559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 06/01/2023] [Accepted: 07/20/2023] [Indexed: 09/28/2023]
Abstract
Heterologous expression of recombinant ion channel subunits in cell lines is often limited by the presence of a low number of channels at the cell surface level. Here, we introduce a combination of two techniques: viral expression using the baculovirus system plus cell-cycle arrest at the G1/S boundary using either thymidine or hydroxyurea. This method achieved a manifold increase in the peak current density of expressed ion channels compared with the classical liposome-mediated transfection methods. The enhanced ionic current was accompanied by an increase in the density of gating charges, confirming that the increased yield of protein and ionic current reflects the functional localization of channels in the plasma membrane. This modified method of viral expression coordinated with the cell cycle arrest will pave the way to better decipher the structure and function of ion channels and their association with ion channelopathies.
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Affiliation(s)
- Ahmed Eltokhi
- Department of Pharmacology, University of Washington, Seattle, WA 98195-7280, USA.
| | - William A Catterall
- Department of Pharmacology, University of Washington, Seattle, WA 98195-7280, USA
| | - Tamer M Gamal El-Din
- Department of Pharmacology, University of Washington, Seattle, WA 98195-7280, USA.
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10
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Sanchez-Sandoval AL, Hernández-Plata E, Gomora JC. Voltage-gated sodium channels: from roles and mechanisms in the metastatic cell behavior to clinical potential as therapeutic targets. Front Pharmacol 2023; 14:1206136. [PMID: 37456756 PMCID: PMC10348687 DOI: 10.3389/fphar.2023.1206136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 06/21/2023] [Indexed: 07/18/2023] Open
Abstract
During the second half of the last century, the prevalent knowledge recognized the voltage-gated sodium channels (VGSCs) as the proteins responsible for the generation and propagation of action potentials in excitable cells. However, over the last 25 years, new non-canonical roles of VGSCs in cancer hallmarks have been uncovered. Their dysregulated expression and activity have been associated with aggressive features and cancer progression towards metastatic stages, suggesting the potential use of VGSCs as cancer markers and prognostic factors. Recent work has elicited essential information about the signalling pathways modulated by these channels: coupling membrane activity to transcriptional regulation pathways, intracellular and extracellular pH regulation, invadopodia maturation, and proteolytic activity. In a promising scenario, the inhibition of VGSCs with FDA-approved drugs as well as with new synthetic compounds, reduces cancer cell invasion in vitro and cancer progression in vivo. The purpose of this review is to present an update regarding recent advances and ongoing efforts to have a better understanding of molecular and cellular mechanisms on the involvement of both pore-forming α and auxiliary β subunits of VGSCs in the metastatic processes, with the aim at proposing VGSCs as new oncological markers and targets for anticancer treatments.
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Affiliation(s)
- Ana Laura Sanchez-Sandoval
- Departamento de Neuropatología Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
- Medicina Genómica, Hospital General de México “Dr Eduardo Liceaga”, Mexico City, Mexico
| | - Everardo Hernández-Plata
- Consejo Nacional de Humanidades, Ciencias y Tecnologías and Instituto Nacional de Medicina Genómica, Mexico City, Mexico
| | - Juan Carlos Gomora
- Departamento de Neuropatología Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
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11
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Das P, Mekonnen B, Alkhofash R, Ingle A, Workman EB, Feather A, Liu P, Lechtreck KF. Small Interactor of PKD2 (SIP), a novel PKD2-related single-pass transmembrane protein, is required for proteolytic processing and ciliary import of Chlamydomonas PKD2. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.13.544839. [PMID: 37398320 PMCID: PMC10312728 DOI: 10.1101/2023.06.13.544839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
In Chlamydomonas cilia, the ciliopathy-relevant TRP channel PKD2 is spatially compartmentalized into a distal region, in which PKD2 binds the axoneme and extracellular mastigonemes, and a smaller proximal region, in which PKD2 is more mobile and lacks mastigonemes. Here, we show that the two PKD2 regions are established early during cilia regeneration and increase in length as cilia elongate. In abnormally long cilia, only the distal region elongated whereas both regions adjusted in length during cilia shortening. In dikaryon rescue experiments, tagged PKD2 rapidly entered the proximal region of PKD2-deficient cilia whereas assembly of the distal region was hindered, suggesting that axonemal docking of PKD2 requires de novo ciliary assembly. We identified Small Interactor of PKD2 (SIP), a small PKD2-related protein, as a novel component of the PKD2-mastigoneme complex. In sip mutants, stability and proteolytic processing of PKD2 in the cell body were reduced and PKD2-mastigoneme complexes were absent from mutant cilia. Like the pkd2 and mst1 mutants, sip swims with reduced velocity. Cilia of the pkd2 mutant beat with normal frequency and bending pattern but were less efficient in moving cells supporting a passive role of the PKD2-SIP-mastigoneme complexes in increasing the effective surface of Chlamydomonas cilia.
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Affiliation(s)
- Poulomi Das
- Department of Cellular Biology, University of Georgia, Athens, GA 30602
| | - Betlehem Mekonnen
- Department of Cellular Biology, University of Georgia, Athens, GA 30602
| | - Rama Alkhofash
- Department of Cellular Biology, University of Georgia, Athens, GA 30602
| | - Abha Ingle
- Department of Computer Science, University of Georgia, Athens, GA 30602
| | - E. Blair Workman
- Department of Cellular Biology, University of Georgia, Athens, GA 30602
| | - Alec Feather
- Department of Cellular Biology, University of Georgia, Athens, GA 30602
| | | | - Karl F. Lechtreck
- Department of Cellular Biology, University of Georgia, Athens, GA 30602
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12
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Schrenk D, Bignami M, Bodin L, Chipman JK, del Mazo J, Grasl‐Kraupp B, Hogstrand C, Hoogenboom L(R, Leblanc J, Nebbia CS, Nielsen E, Ntzani E, Petersen A, Sand S, Schwerdtle T, Vleminckx C, Dusemund B, Hart A, Mulder P, Viviani B, Anastassiadou M, Cascio C, Riolo F, Wallace H. Risks for human health related to the presence of grayanotoxins in certain honey. EFSA J 2023; 21:e07866. [PMID: 36875862 PMCID: PMC9978999 DOI: 10.2903/j.efsa.2023.7866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023] Open
Abstract
The European Commission asked EFSA for a scientific opinion on the risks for human health of the presence of grayanotoxins (GTXs) in 'certain honey' from Ericaceae plants. The risk assessment included all structurally related grayananes occurring with GTXs in 'certain' honey. Oral exposure is associated with acute intoxication in humans. Acute symptoms affect the muscles, nervous and cardiovascular systems. These may lead to complete atrioventricular block, convulsions, mental confusion, agitation, syncope and respiratory depression. For acute effects, the CONTAM Panel derived a reference point (RP) of 15.3 μg/kg body weight for the sum of GTX I and III based on a BMDL10 for reduced heart rate in rats. A similar relative potency was considered for GTX I. Without chronic toxicity studies, an RP for long-term effects could not be derived. There is evidence for genotoxicity in mice exposed to GTX III or honey containing GTX I and III, showing increased levels of chromosomal damage. The mechanism of genotoxicity is unknown. Without representative occurrence data for the sum of GTX I and III and consumption data from Ericaceae honey, acute dietary exposure was estimated based on selected concentrations for GTX I and III reflecting concentrations measured in 'certain' honeys. Applying a margin of exposure (MOE) approach, the estimated MOEs raised health concerns for acute toxicity. The Panel calculated the highest concentrations for GTX I and III below which no acute effects would be expected following 'certain honey' consumption. The Panel is 75% or more certain that the calculated highest concentration of 0.05 mg for the sum of GTX I and III per kg honey is protective for all age groups regarding acute intoxications. This value does not consider other grayananes in 'certain honey' and does not cover the identified genotoxicity.
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13
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vom Dahl C, Müller CE, Berisha X, Nagel G, Zimmer T. Coupling the Cardiac Voltage-Gated Sodium Channel to Channelrhodopsin-2 Generates Novel Optical Switches for Action Potential Studies. MEMBRANES 2022; 12:907. [PMID: 36295666 PMCID: PMC9607247 DOI: 10.3390/membranes12100907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 09/09/2022] [Accepted: 09/12/2022] [Indexed: 06/16/2023]
Abstract
Voltage-gated sodium (Na+) channels respond to short membrane depolarization with conformational changes leading to pore opening, Na+ influx, and action potential (AP) upstroke. In the present study, we coupled channelrhodopsin-2 (ChR2), the key ion channel in optogenetics, directly to the cardiac voltage-gated Na+ channel (Nav1.5). Fusion constructs were expressed in Xenopus laevis oocytes, and electrophysiological recordings were performed by the two-microelectrode technique. Heteromeric channels retained both typical Nav1.5 kinetics and light-sensitive ChR2 properties. Switching to the current-clamp mode and applying short blue-light pulses resulted either in subthreshold depolarization or in a rapid change of membrane polarity typically seen in APs of excitable cells. To study the effect of individual K+ channels on the AP shape, we co-expressed either Kv1.2 or hERG with one of the Nav1.5-ChR2 fusions. As expected, both delayed rectifier K+ channels shortened AP duration significantly. Kv1.2 currents remarkably accelerated initial repolarization, whereas hERG channel activity efficiently restored the resting membrane potential. Finally, we investigated the effect of the LQT3 deletion mutant ΔKPQ on the AP shape and noticed an extremely prolonged AP duration that was directly correlated to the size of the non-inactivating Na+ current fraction. In conclusion, coupling of ChR2 to a voltage-gated Na+ channel generates optical switches that are useful for studying the effect of individual ion channels on the AP shape. Moreover, our novel optogenetic approach provides the potential for an application in pharmacology and optogenetic tissue-engineering.
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Affiliation(s)
- Christian vom Dahl
- Institute of Physiology II, University Hospital Jena, Friedrich Schiller University, 07740 Jena, Germany
| | - Christoph Emanuel Müller
- Institute of Physiology II, University Hospital Jena, Friedrich Schiller University, 07740 Jena, Germany
| | - Xhevat Berisha
- Institute of Physiology II, University Hospital Jena, Friedrich Schiller University, 07740 Jena, Germany
| | - Georg Nagel
- Institute of Physiology—Neurophysiology, Julius Maximilians University, 97070 Wuerzburg, Germany
| | - Thomas Zimmer
- Institute of Physiology II, University Hospital Jena, Friedrich Schiller University, 07740 Jena, Germany
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14
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Role of Omics in Migraine Research and Management: A Narrative Review. Mol Neurobiol 2022; 59:5809-5834. [PMID: 35796901 DOI: 10.1007/s12035-022-02930-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 06/14/2022] [Indexed: 10/17/2022]
Abstract
Migraine is a neurological disorder defined by episodic attacks of chronic pain associated with nausea, photophobia, and phonophobia. It is known to be a complex disease with several environmental and genetic factors contributing to its susceptibility. Risk factors for migraine include head or neck injury (Arnold, Cephalalgia 38(1):1-211, 2018). Stress and high temperature are known to trigger migraine, while sleep disorders and anxiety are considered to be the comorbid conditions with migraine. Studies have reported various biomarkers, including genetic variants, proteins, and metabolites implicated in migraine's pathophysiology. Using the "omics" approach, which deals with genetics, transcriptomics, proteomics, and metabolomics, more specific biomarkers for various migraine can be identified. On account of its multifactorial nature, migraine is an ideal study model focusing on integrated omics approaches, including genomics, transcriptomics, proteomics, and metabolomics. The current review has been compiled with an aim to focus on the genomic alterations especially involved in the regulation of glutamatergic neurotransmission, cortical excitability, ion channels, solute carrier proteins, or receptors; their expression in migraine patients and also specific proteins and metabolites, including some inflammatory biomarkers that might represent the migraine phenotype at the molecular level. The systems biology approach holds the promise to understand the pathophysiology of the disease at length and also to identify the specific therapeutic targets for novel interventions.
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15
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Reimche JS, Del Carlo RE, Brodie ED, McGlothlin JW, Schlauch K, Pfrender ME, Brodie ED, Leblanc N, Feldman CR. The road not taken: Evolution of tetrodotoxin resistance in the Sierra garter snake (Thamnophis couchii) by a path less traveled. Mol Ecol 2022; 31:3827-3843. [PMID: 35596742 DOI: 10.1111/mec.16538] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 04/28/2022] [Accepted: 05/12/2022] [Indexed: 11/27/2022]
Abstract
The repeated evolution of tetrodotoxin (TTX) resistance provides a model for testing hypotheses about the mechanisms of convergent evolution. This poison is broadly employed as a potent antipredator defense, blocking voltage-gated sodium channels (Nav ) in muscles and nerves, paralyzing and sometimes killing predators. Resistance in taxa bearing this neurotoxin and a few predators appears to come from convergent replacements in specific Nav residues that interact with TTX. This stereotyped genetic response suggests molecular and phenotypic evolution may be constrained and predictable. Here, we investigate the extent of mechanistic convergence in garter snakes (Thamnophis) that prey on TTX-bearing newts (Taricha) by examining the physiological and genetic basis of TTX resistance in the Sierra garter snake (Th. couchii). We characterize variation in this predatory adaptation across populations at several biological scales: whole-animal TTX resistance; skeletal muscle resistance, functional genetic variation in three Nav encoding loci; and levels of gene expression for one of these loci. We found Th. couchii possess extensive geographic variation in resistance at the whole-animal and skeletal muscle levels. As in other Thamnophis, resistance at both levels is highly correlated, suggesting convergence across the biological levels linking organism to organ. However, Th. couchii shows no functional variation in Nav loci among populations or difference in candidate gene expression. Local variation in TTX resistance in Th. couchii cannot be explained by the same relationship between genotype and phenotype seen in other taxa. Thus, historical contingencies may lead different species of Thamnophis down alternative routes to local adaptation.
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Affiliation(s)
- Jessica S Reimche
- Department of Biology, Evolution, and Conservation Biology, University of Nevada, Reno, NV, USA.,Program in Ecology, Evolution, and Conservation Biology, University of Nevada, Reno, NV, USA
| | - Robert E Del Carlo
- Department of Pharmacology and 4Program in Cellular and Molecular Pharmacology and Physiology, University of Nevada, Reno, NV, USA
| | - Edmund D Brodie
- Department of Biology, Utah State University, Logan, UT, USA
| | - Joel W McGlothlin
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA, USA
| | | | - Michael E Pfrender
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
| | - Edmund D Brodie
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - Normand Leblanc
- Department of Pharmacology and 4Program in Cellular and Molecular Pharmacology and Physiology, University of Nevada, Reno, NV, USA
| | - Chris R Feldman
- Department of Biology, Evolution, and Conservation Biology, University of Nevada, Reno, NV, USA.,Program in Ecology, Evolution, and Conservation Biology, University of Nevada, Reno, NV, USA
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16
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Oshiyama NF, Pereira AHM, Cardoso AC, Franchini KG, Bassani JWM, Bassani RA. Developmental differences in myocardial transmembrane Na + transport: Implications for excitability and Na + handling. J Physiol 2022; 600:2651-2667. [PMID: 35489088 DOI: 10.1113/jp282661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 04/20/2022] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Previous studies showed that myocardial preparations from immature rats are less sensitive to electrical field stimulation than adult preparations. Freshly-isolated ventricular myocytes from neonatal rats showed lower excitability than adult cells, e.g., less negative threshold membrane potential and greater membrane depolarization required for action potential triggering. In addition to differences in mRNA levels for Na+ channels isoforms and greater Na+ current (INa ) density, Na+ channel voltage-dependence was shifted to the right in immature myocytes, which seems to be sufficient to decrease excitability, according to computer simulations. Only in neonatal myocytes did cyclic activity promote marked cytosolic Na+ accumulation, which was prevented by abolition of systolic Ca2+ transients by blockade of Ca2+ currents. Developmental changes in INa may account for the difference in action potential initiation parameters, but not for cytosolic Na+ accumulation, which seems to be due mainly to Na+ /Ca2+ exchanger-mediated Na+ influx. ABSTRACT Little is currently known about possible developmental changes in myocardial Na+ handling, which may have impact on cell excitability and Ca2+ content. Resting intracellular Na+ concentration ([Na+ ]i ), measured in freshly-isolated rat ventricular myocytes with CoroNa-green, was not significantly different in neonates (3-5 days old) and adults, but electrical stimulation caused marked [Na+ ]i rise only in neonates. Inhibition of L-type Ca2+ current by CdCl2 abolished not only systolic Ca2+ transients, but also activity-dependent intracellular Na+ accumulation in immature cells. This indicates that the main Na+ influx pathway during activity is the Na+ /Ca2+ exchanger, rather than voltage-dependent Na+ current (INa ), which was not affected by CdCl2 . In immature myocytes, INa density was 2-fold greater, inactivation was faster, and the current peak occurred at less negative transmembrane potential (Em ) than in adults. Na+ channel steady-state activation and inactivation curves in neonates showed a rightward shift, which should increase channel availability at diastolic Em , but also require greater depolarization for excitation, which was observed experimentally and reproduced in computer simulations. Ventricular mRNA levels of Nav 1.1, Nav 1.4 and Nav 1.5 pore-forming isoforms were greater in neonate ventricles, while decrease was seen for the β1 subunit. Both molecular and biophysical changes in the channel profile may contribute to the differences in INa density and voltage-dependence, and also to the less negative threshold Em in neonates, compared to adults. The apparently lower excitability in immature ventricle may confer protection against the development of spontaneous activity in this tissue. Abstract figure legend Little is currently known about possible developmental changes in myocardial Na+ transport, which may have impact on cell excitability and other physiological aspects. At the mRNA level, neonatal rat ventricle expresses a greater variety of Na+ channel isoforms than in adults. In immature ventricular cardiomyocytes, Na+ current (INa ) density was greater, but voltage-dependence is shifted to less negative potentials than in adults. This should increase channel availability at diastolic membrane potential, but also require greater depolarization for excitation, which was observed experimentally and reproduced in computer simulation. We also observed that electrical stimulation caused marked intracellular Na+ accumulation only in neonates, which was abolished when Ca2+ transients and the Na+ /Ca2+ exchanger (NCX) were inhibited by Cd2+ + Ni2+ . Thus, it seems that the main Na+ influx pathway during activity in neonates is the NCX, rather than voltage-dependent INa , which was not affected by these blockers. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Natália F Oshiyama
- Department of Biomedical Engineering, School of Electrical and Computer Engineering, University of Campinas, Campinas, SP, Brazil.,National Laboratory for Cell Calcium Study, (LabNECC), Center for Biomedical Engineering, University of Campinas, Campinas, SP, Brazil
| | - Ana H M Pereira
- Brazilian Biosciences National Laboratory, Brazilian Center for Research in Energy and Materials (LNBio/CNPEM), Campinas, SP, Brazil
| | - Alisson C Cardoso
- Brazilian Biosciences National Laboratory, Brazilian Center for Research in Energy and Materials (LNBio/CNPEM), Campinas, SP, Brazil
| | - Kleber G Franchini
- Brazilian Biosciences National Laboratory, Brazilian Center for Research in Energy and Materials (LNBio/CNPEM), Campinas, SP, Brazil.,Department of Internal Medicine, School of Medicine, University of Campinas, Campinas, SP, Brazil
| | - José W M Bassani
- Department of Biomedical Engineering, School of Electrical and Computer Engineering, University of Campinas, Campinas, SP, Brazil.,National Laboratory for Cell Calcium Study, (LabNECC), Center for Biomedical Engineering, University of Campinas, Campinas, SP, Brazil
| | - Rosana A Bassani
- Department of Biomedical Engineering, School of Electrical and Computer Engineering, University of Campinas, Campinas, SP, Brazil.,National Laboratory for Cell Calcium Study, (LabNECC), Center for Biomedical Engineering, University of Campinas, Campinas, SP, Brazil
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17
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Körner J, Albani S, Sudha Bhagavath Eswaran V, Roehl AB, Rossetti G, Lampert A. Sodium Channels and Local Anesthetics-Old Friends With New Perspectives. Front Pharmacol 2022; 13:837088. [PMID: 35418860 PMCID: PMC8996304 DOI: 10.3389/fphar.2022.837088] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 02/16/2022] [Indexed: 12/11/2022] Open
Abstract
The long history of local anesthetics (LAs) starts out in the late 19th century when the content of coca plant leaves was discovered to alleviate pain. Soon after, cocaine was established and headed off to an infamous career as a substance causing addiction. Today, LAs and related substances-in modified form-are indispensable in our clinical everyday life for pain relief during and after minor and major surgery, and dental practices. In this review, we elucidate on the interaction of modern LAs with their main target, the voltage-gated sodium channel (Navs), in the light of the recently published channel structures. Knowledge of the 3D interaction sites of the drug with the protein will allow to mechanistically substantiate the comprehensive data available on LA gating modification. In the 1970s it was suggested that LAs can enter the channel pore from the lipid phase, which was quite prospective at that time. Today we know from cryo-electron microscopy structures and mutagenesis experiments, that indeed Navs have side fenestrations facing the membrane, which are likely the entrance for LAs to induce tonic block. In this review, we will focus on the effects of LA binding on fast inactivation and use-dependent inhibition in the light of the proposed new allosteric mechanism of fast inactivation. We will elaborate on subtype and species specificity and provide insights into modelling approaches that will help identify the exact molecular binding orientation, access pathways and pharmacokinetics. With this comprehensive overview, we will provide new perspectives in the use of the drug, both clinically and as a tool for basic ion channel research.
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Affiliation(s)
- Jannis Körner
- Institute of Physiology, Aachen, Germany.,Clinic of Anesthesiology, Medical Faculty, Uniklinik RWTH Aachen, Aachen, Germany
| | - Simone Albani
- Institute for Neuroscience and Medicine (INM-9/IAS-5), Forschungszentrum Jülich, Jülich, Germany.,Faculty of Mathematics, Computer Science and Natural Sciences, RWTH Aachen, Aachen, Germany
| | | | - Anna B Roehl
- Clinic of Anesthesiology, Medical Faculty, Uniklinik RWTH Aachen, Aachen, Germany
| | - Giulia Rossetti
- Institute for Neuroscience and Medicine (INM-9/IAS-5), Forschungszentrum Jülich, Jülich, Germany.,Jülich Supercomputing Center (JSC), Forschungszentrum Jülich, Aachen, Germany.,Department of Neurology, University Hospital Aachen, RWTH Aachen University, Aachen, Germany
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18
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Kong X, Li Y, Perez-Miller S, Luo G, Liao Q, Wu X, Liang S, Tang C, Khanna R, Liu Z. The small molecule compound C65780 alleviates pain by stabilizing voltage-gated sodium channels in the inactivated and slowly-recovering state. Neuropharmacology 2022; 212:109057. [DOI: 10.1016/j.neuropharm.2022.109057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 03/23/2022] [Accepted: 04/05/2022] [Indexed: 11/30/2022]
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19
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Krahn AD, Behr ER, Hamilton R, Probst V, Laksman Z, Han HC. Brugada Syndrome. JACC Clin Electrophysiol 2022; 8:386-405. [PMID: 35331438 DOI: 10.1016/j.jacep.2021.12.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 12/09/2021] [Accepted: 12/15/2021] [Indexed: 12/15/2022]
Abstract
Brugada syndrome (BrS) is an "inherited" condition characterized by predisposition to syncope and cardiac arrest, predominantly during sleep. The prevalence is ∼1:2,000, and is more commonly diagnosed in young to middle-aged males, although patient sex does not appear to impact prognosis. Despite the perception of BrS being an inherited arrhythmia syndrome, most cases are not associated with a single causative gene variant. Electrocardiogram (ECG) findings support variable extent of depolarization and repolarization changes, with coved ST-segment elevation ≥2 mm and a negative T-wave in the right precordial leads. These ECG changes are often intermittent, and may be provoked by fever or sodium channel blocker challenge. Growing evidence from cardiac imaging, epicardial ablation, and pathology studies suggests the presence of an epicardial arrhythmic substrate within the right ventricular outflow tract. Risk stratification aims to identify those who are at increased risk of sudden cardiac death, with well-established factors being the presence of spontaneous ECG changes and a history of cardiac arrest or cardiogenic syncope. Current management involves conservative measures in asymptomatic patients, including fever management and drug avoidance. Symptomatic patients typically undergo implantable cardioverter defibrillator insertion, with quinidine and epicardial ablation used for patients with recurrent arrhythmia. This review summarizes our current understanding of BrS and provides clinicians with a practical approach to diagnosis and management.
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Affiliation(s)
- Andrew D Krahn
- Center for Cardiovascular Innovation, Heart Rhythm Services, Division of Cardiology, University of British Columbia, Vancouver, British Columbia, Canada.
| | - Elijah R Behr
- Cardiovascular Clinical Academic Group and Cardiology Research Centre, St. George's, University of London and St. George's University Hospitals NHS Foundation Trust, London, United Kingdom
| | - Robert Hamilton
- Department of Pediatrics (Cardiology), The Labatt Family Heart Centre and Translational Medicine, The Hospital for Sick Children & Research Institute and the University of Toronto, Toronto, Canada
| | - Vincent Probst
- Cardiologic Department and Reference Center for Hereditary Arrhythmic Diseases, Nantes University Hospital, Nantes, France
| | - Zachary Laksman
- Center for Cardiovascular Innovation, Heart Rhythm Services, Division of Cardiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Hui-Chen Han
- Center for Cardiovascular Innovation, Heart Rhythm Services, Division of Cardiology, University of British Columbia, Vancouver, British Columbia, Canada; Victorian Heart Institute, Monash University, Clayton, Victoria, Australia
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20
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Nevin ST, Lawrence N, Nicke A, Lewis RJ, Adams DJ. Functional modulation of the human voltage-gated sodium channel Na V1.8 by auxiliary β subunits. Channels (Austin) 2021; 15:79-93. [PMID: 33315536 PMCID: PMC7781643 DOI: 10.1080/19336950.2020.1860399] [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: 11/24/2020] [Revised: 11/30/2020] [Accepted: 11/30/2020] [Indexed: 12/03/2022] Open
Abstract
The voltage-gated sodium channel Nav1.8 mediates the tetrodotoxin-resistant (TTX-R) Na+ current in nociceptive primary sensory neurons, which has an important role in the transmission of painful stimuli. Here, we describe the functional modulation of the human Nav1.8 α-subunit in Xenopus oocytes by auxiliary β subunits. We found that the β3 subunit down-regulated the maximal Na+ current amplitude and decelerated recovery from inactivation of hNav1.8, whereas the β1 and β2 subunits had no such effects. The specific regulation of Nav1.8 by the β3 subunit constitutes a potential novel regulatory mechanism of the TTX-R Na+ current in primary sensory neurons with potential implications in chronic pain states. In particular, neuropathic pain states are characterized by a down-regulation of Nav1.8 accompanied by increased expression of the β3 subunit. Our results suggest that these two phenomena may be correlated, and that increased levels of the β3 subunit may directly contribute to the down-regulation of Nav1.8. To determine which domain of the β3 subunit is responsible for the specific regulation of hNav1.8, we created chimeras of the β1 and β3 subunits and co-expressed them with the hNav1.8 α-subunit in Xenopus oocytes. The intracellular domain of the β3 subunit was shown to be responsible for the down-regulation of maximal Nav1.8 current amplitudes. In contrast, the extracellular domain mediated the effect of the β3 subunit on hNav1.8 recovery kinetics.
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Affiliation(s)
- S. T. Nevin
- School of Biomedical Sciences and the Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
| | - N. Lawrence
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
| | - A. Nicke
- School of Biomedical Sciences and the Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
| | - R. J. Lewis
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
| | - D. J. Adams
- School of Biomedical Sciences and the Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, Australia
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21
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Stucky CL, Mikesell AR. Cutaneous pain in disorders affecting peripheral nerves. Neurosci Lett 2021; 765:136233. [PMID: 34506882 PMCID: PMC8579816 DOI: 10.1016/j.neulet.2021.136233] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 08/16/2021] [Accepted: 09/02/2021] [Indexed: 02/08/2023]
Abstract
Our ability to quickly detect and respond to harmful environmental stimuli is vital for our safety and survival. This inherent acute pain detection is a "gift" because it both protects our body from harm and allows healing of damaged tissues [1]. Damage to tissues from trauma or disease can result in distorted or amplified nociceptor signaling and sensitization of the spinal cord and brain (Central Nervous System; CNS) pathways to normal input from light touch mechanoreceptors. Together, these processes can result in nagging to unbearable chronic pain and extreme sensitivity to light skin touch (allodynia). Unlike acute protective pain, chronic pain and allodynia serve no useful purpose and can severely reduce the quality of life of an affected person. Chronic pain can arise from impairment to peripheral neurons, a phenomenon called "peripheral neuropathic pain." Peripheral neuropathic pain can be caused by many insults that directly affect peripheral sensory neurons, including mechanical trauma, metabolic imbalance (e.g., diabetes), autoimmune diseases, chemotherapeutic agents, viral infections (e.g., shingles). These insults cause "acquired" neuropathies such as small-fiber neuropathies, diabetic neuropathy, chemotherapy-induced peripheral neuropathy, and post herpetic neuralgia. Peripheral neuropathic pain can also be caused by genetic factors and result in hereditary neuropathies that include Charcot-Marie-Tooth disease, rare channelopathies and Fabry disease. Many acquired and hereditary neuropathies affect the skin, our largest organ and protector of nearly our entire body. Here we review how cutaneous nociception (pain perceived from the skin) is altered following diseases that affect peripheral nerves that innervate the skin. We provide an overview of how noxious stimuli are detected and encoded by molecular transducers on subtypes of cutaneous afferent endings and conveyed to the CNS. Next, we discuss several acquired and hereditary diseases and disorders that cause painful or insensate (lack of sensation) cutaneous peripheral neuropathies, the symptoms and percepts patients experience, and how cutaneous afferents and other peripheral cell types are altered in function in these disorders. We highlight exciting new research areas that implicate non-neuronal skin cells, particularly keratinocytes, in cutaneous nociception and peripheral neuropathies. Finally, we conclude with ideas for innovative new directions, areas of unmet need, and potential opportunities for novel cutaneous therapeutics that may avoid CNS side effects, as well as ideas for improved translation of mechanisms identified in preclinical models to patients.
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Affiliation(s)
- Cheryl L Stucky
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, United States.
| | - Alexander R Mikesell
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, United States
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22
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Takla M, Edling CE, Zhang K, Saadeh K, Tse G, Salvage SC, Huang CL, Jeevaratnam K. Transcriptional profiles of genes related to electrophysiological function in Scn5a +/- murine hearts. Physiol Rep 2021; 9:e15043. [PMID: 34617689 PMCID: PMC8495800 DOI: 10.14814/phy2.15043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 08/13/2021] [Accepted: 08/13/2021] [Indexed: 11/24/2022] Open
Abstract
The Scn5a gene encodes the major pore-forming Nav 1.5 (α) subunit, of the voltage-gated Na+ channel in cardiomyocytes. The key role of Nav 1.5 in action potential initiation and propagation in both atria and ventricles predisposes organisms lacking Scn5a or carrying Scn5a mutations to cardiac arrhythmogenesis. Loss-of-function Nav 1.5 genetic abnormalities account for many cases of the human arrhythmic disorder Brugada syndrome (BrS) and related conduction disorders. A murine model with a heterozygous Scn5a deletion recapitulates many electrophysiological phenotypes of BrS. This study examines the relationships between its Scn5a+/- genotype, resulting transcriptional changes, and the consequent phenotypic presentations of BrS. Of 62 selected protein-coding genes related to cardiomyocyte electrophysiological or homeostatic function, concentrations of mRNA transcribed from 15 differed significantly from wild type (WT). Despite halving apparent ventricular Scn5a transcription heterozygous deletion did not significantly downregulate its atrial expression, raising possibilities of atria-specific feedback mechanisms. Most of the remaining 14 genes whose expression differed significantly between WT and Scn5a+/- animals involved Ca2+ homeostasis specifically in atrial tissue, with no overlap with any ventricular changes. All statistically significant changes in expression were upregulations in the atria and downregulations in the ventricles. This investigation demonstrates the value of future experiments exploring for and clarifying links between transcriptional control of Scn5a and of genes whose protein products coordinate Ca2+ regulation and examining their possible roles in BrS.
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Affiliation(s)
- Michael Takla
- Faculty of Health and Medical ScienceUniversity of SurreyGuildfordUK
- Christ’s CollegeUniversity of CambridgeCambridgeUK
| | | | - Kevin Zhang
- Faculty of Health and Medical ScienceUniversity of SurreyGuildfordUK
- School of MedicineImperial College LondonLondonUK
| | - Khalil Saadeh
- Faculty of Health and Medical ScienceUniversity of SurreyGuildfordUK
- Clinical SchoolUniversity of CambridgeCambridgeUK
| | - Gary Tse
- Faculty of Health and Medical ScienceUniversity of SurreyGuildfordUK
- Second Hospital of Tianjin Medical UniversityTianjinChina
| | | | - Christopher L.‐H. Huang
- Faculty of Health and Medical ScienceUniversity of SurreyGuildfordUK
- Department of BiochemistryUniversity of CambridgeCambridgeUK
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23
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Blandin CE, Gravez BJ, Hatem SN, Balse E. Remodeling of Ion Channel Trafficking and Cardiac Arrhythmias. Cells 2021; 10:cells10092417. [PMID: 34572065 PMCID: PMC8468138 DOI: 10.3390/cells10092417] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 09/08/2021] [Accepted: 09/11/2021] [Indexed: 01/08/2023] Open
Abstract
Both inherited and acquired cardiac arrhythmias are often associated with the abnormal functional expression of ion channels at the cellular level. The complex machinery that continuously traffics, anchors, organizes, and recycles ion channels at the plasma membrane of a cardiomyocyte appears to be a major source of channel dysfunction during cardiac arrhythmias. This has been well established with the discovery of mutations in the genes encoding several ion channels and ion channel partners during inherited cardiac arrhythmias. Fibrosis, altered myocyte contacts, and post-transcriptional protein changes are common factors that disorganize normal channel trafficking during acquired cardiac arrhythmias. Channel availability, described notably for hERG and KV1.5 channels, could be another potent arrhythmogenic mechanism. From this molecular knowledge on cardiac arrhythmias will emerge novel antiarrhythmic strategies.
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Affiliation(s)
- Camille E. Blandin
- INSERM, Unité de Recherche sur les Maladies Cardiovasculaires, le Métabolisme et la Nutrition—UNITE 1166, Sorbonne Université, EQUIPE 3, F-75013 Paris, France; (C.E.B.); (B.J.G.); (S.N.H.)
| | - Basile J. Gravez
- INSERM, Unité de Recherche sur les Maladies Cardiovasculaires, le Métabolisme et la Nutrition—UNITE 1166, Sorbonne Université, EQUIPE 3, F-75013 Paris, France; (C.E.B.); (B.J.G.); (S.N.H.)
| | - Stéphane N. Hatem
- INSERM, Unité de Recherche sur les Maladies Cardiovasculaires, le Métabolisme et la Nutrition—UNITE 1166, Sorbonne Université, EQUIPE 3, F-75013 Paris, France; (C.E.B.); (B.J.G.); (S.N.H.)
- ICAN—Institute of Cardiometabolism and Nutrition, Institute of Cardiology, Pitié-Salpêtrière Hospital, Sorbonne University, F-75013 Paris, France
| | - Elise Balse
- INSERM, Unité de Recherche sur les Maladies Cardiovasculaires, le Métabolisme et la Nutrition—UNITE 1166, Sorbonne Université, EQUIPE 3, F-75013 Paris, France; (C.E.B.); (B.J.G.); (S.N.H.)
- Correspondence:
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24
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Doray A, Lemoine R, Severin M, Chadet S, Lopez-Charcas O, Héraud A, Baron C, Besson P, Monteil A, Pedersen SF, Roger S. The Voltage-Gated Sodium Channel Beta4 Subunit Maintains Epithelial Phenotype in Mammary Cells. Cells 2021; 10:1624. [PMID: 34209614 PMCID: PMC8304757 DOI: 10.3390/cells10071624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 06/17/2021] [Accepted: 06/25/2021] [Indexed: 11/16/2022] Open
Abstract
The SCN4B gene, coding for the NaVβ4 subunit of voltage-gated sodium channels, was recently found to be expressed in normal epithelial cells and down-regulated in several cancers. However, its function in normal epithelial cells has not been characterized. In this study, we demonstrated that reducing NaVβ4 expression in MCF10A non-cancer mammary epithelial cells generated important morphological changes observed both in two-dimensional cultures and in three-dimensional cysts. Most notably, the loss of NaVβ4 induced a complete loss of epithelial organisation in cysts and increased proteolytic activity towards the extracellular matrix. Loss of epithelial morphology was associated with an increased degradation of β-catenin, reduced E-cadherin expression and induction of mesenchymal markers N-cadherin, vimentin, and α-SMA expression. Overall, our results suggest that Navβ4 may participate in the maintenance of the epithelial phenotype in mammary cells and that its downregulation might be a determining step in early carcinogenesis.
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Affiliation(s)
- Adélaïde Doray
- Transplantation, Immunologie et Inflammation T2I-EA 4245, Université de Tours, 37044 Tours, France; (A.D.); (R.L.); (S.C.); (O.L.-C.); (A.H.); (C.B.); (P.B.)
| | - Roxane Lemoine
- Transplantation, Immunologie et Inflammation T2I-EA 4245, Université de Tours, 37044 Tours, France; (A.D.); (R.L.); (S.C.); (O.L.-C.); (A.H.); (C.B.); (P.B.)
| | - Marc Severin
- Section for Cell Biology and Physiology, Department of Biology, Faculty of Science, University of Copenhagen, 2100 Copenhagen, Denmark; (M.S.); (S.F.P.)
| | - Stéphanie Chadet
- Transplantation, Immunologie et Inflammation T2I-EA 4245, Université de Tours, 37044 Tours, France; (A.D.); (R.L.); (S.C.); (O.L.-C.); (A.H.); (C.B.); (P.B.)
| | - Osbaldo Lopez-Charcas
- Transplantation, Immunologie et Inflammation T2I-EA 4245, Université de Tours, 37044 Tours, France; (A.D.); (R.L.); (S.C.); (O.L.-C.); (A.H.); (C.B.); (P.B.)
| | - Audrey Héraud
- Transplantation, Immunologie et Inflammation T2I-EA 4245, Université de Tours, 37044 Tours, France; (A.D.); (R.L.); (S.C.); (O.L.-C.); (A.H.); (C.B.); (P.B.)
| | - Christophe Baron
- Transplantation, Immunologie et Inflammation T2I-EA 4245, Université de Tours, 37044 Tours, France; (A.D.); (R.L.); (S.C.); (O.L.-C.); (A.H.); (C.B.); (P.B.)
| | - Pierre Besson
- Transplantation, Immunologie et Inflammation T2I-EA 4245, Université de Tours, 37044 Tours, France; (A.D.); (R.L.); (S.C.); (O.L.-C.); (A.H.); (C.B.); (P.B.)
| | - Arnaud Monteil
- Institut de Génomique Fonctionnelle, University of Montpellier, CNRS UMR 5203, INSERM U1191, 34094 Montpellier, France;
| | - Stine Falsig Pedersen
- Section for Cell Biology and Physiology, Department of Biology, Faculty of Science, University of Copenhagen, 2100 Copenhagen, Denmark; (M.S.); (S.F.P.)
| | - Sébastien Roger
- Transplantation, Immunologie et Inflammation T2I-EA 4245, Université de Tours, 37044 Tours, France; (A.D.); (R.L.); (S.C.); (O.L.-C.); (A.H.); (C.B.); (P.B.)
- Institut Universitaire de France (IUF), 75231 Paris, France
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25
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Chemometric Models of Differential Amino Acids at the Na vα and Na vβ Interface of Mammalian Sodium Channel Isoforms. Molecules 2020; 25:molecules25153551. [PMID: 32756517 PMCID: PMC7435598 DOI: 10.3390/molecules25153551] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 07/21/2020] [Accepted: 07/22/2020] [Indexed: 12/19/2022] Open
Abstract
(1) Background: voltage-gated sodium channels (Navs) are integral membrane proteins that allow the sodium ion flux into the excitable cells and initiate the action potential. They comprise an α (Navα) subunit that forms the channel pore and are coupled to one or more auxiliary β (Navβ) subunits that modulate the gating to a variable extent. (2) Methods: after performing homology in silico modeling for all nine isoforms (Nav1.1α to Nav1.9α), the Navα and Navβ protein-protein interaction (PPI) was analyzed chemometrically based on the primary and secondary structures as well as topological or spatial mapping. (3) Results: our findings reveal a unique isoform-specific correspondence between certain segments of the extracellular loops of the Navα subunits. Precisely, loop S5 in domain I forms part of the PPI and assists Navβ1 or Navβ3 on all nine mammalian isoforms. The implied molecular movements resemble macroscopic springs, all of which explains published voltage sensor effects on sodium channel fast inactivation in gating. (4) Conclusions: currently, the specific functions exerted by the Navβ1 or Navβ3 subunits on the modulation of Navα gating remain unknown. Our work determined functional interaction in the extracellular domains on theoretical grounds and we propose a schematic model of the gating mechanism of fast channel sodium current inactivation by educated guessing.
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Exercise-Induced Cognitive Improvement Is Associated with Sodium Channel-Mediated Excitability in APP/PS1 Mice. Neural Plast 2020; 2020:9132720. [PMID: 32256560 PMCID: PMC7103997 DOI: 10.1155/2020/9132720] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 02/16/2020] [Accepted: 02/19/2020] [Indexed: 12/19/2022] Open
Abstract
Elevated brain activation, or hyperexcitability, induces cognitive impairment and confers an increased risk of Alzheimer's disease (AD). Blocking the overexcitation of the neural network may be a promising new strategy to prevent, halt, and even reverse this condition. Physical exercise has been shown to be an effective cognitive enhancer that reduces the risk of AD in elderly individuals, but the underlying mechanisms are far from being fully understood. We explored whether long-term treadmill exercise attenuates amyloid precursor protein (APP)/presenilin-1 (PS1) mutation-induced aberrant network activity and thus improves cognition by altering the numbers and/or distribution of voltage-gated sodium channels (Nav) in transgenic mice. APP/PS1 mice aged 2, 3.5, 5, 6.5, 8, and 9 months underwent treadmill exercise with different durations or at different stages of AD. The alterations in memory, electroencephalogram (EEG) recordings, and expression levels and distributions of Nav functional members (Nav1.1α, Nav1.2, Nav1.6, and Navβ2) were evaluated. The results revealed that treadmill exercise with 12- and 24-week durations 1) induced significant improvement in novel object recognition (NOR) memory and Morris water maze (MWM) spatial memory; 2) partially reduced abnormal spike activity; and 3) redressed the disturbed cellular distribution of Nav1.1α, aberrant Navβ2 cleavage augmentation, and Nav1.6 upregulation. Additionally, APP/PS1 mice in the 24-week exercise group showed better performance in the NOR task and a large decrease in Nav1.6 expression, which was close to the wild-type level. This study suggests that exercise improves cognition and neural activity by altering the numbers and distribution of hippocampal Nav in APP/PS1 mice. Long-term treadmill exercise, for about 24 weeks, starting in the preclinical stage, is a promising therapeutic strategy for preventing AD and halting its progress.
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Wang L, Han Z, Dai J, Cao K. Brugada Syndrome Caused by Sodium Channel Dysfunction Associated with a SCN1B Variant A197V. Arch Med Res 2020; 51:245-253. [PMID: 32192759 DOI: 10.1016/j.arcmed.2020.02.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 01/18/2020] [Accepted: 02/10/2020] [Indexed: 12/14/2022]
Abstract
OBJECTIVE We aimed to identify and characterize a SCN1B variant, A197V, associated with Brugada Syndrome (BrS). METHODS Whole-exome sequencing was employed to explore the potential causative genes in 8 unrelated clinically diagnosed BrS patients. A197V variant was only detected in exon 4 of SCN1B in a 46 year old patient, who was admitted due to syncope. Wild type (WT) and mutant (A197V) genes were co-expressed with SCN5A in human embryonic kidney cells (HEK293 cells) and studied using whole-cell patch clamp and immunodetection techniques. RESULTS Coexpression of 5A/WT + 1B/A197V resulted in a marked decrease in current density compared to 5A/WT + 1B/WT. The activation velocity was decelerated by A197V mutation. No significant changes were observed in recovery from inactivation parameters. Cell surface protein analyses confirmed that Nav1.5 channel membrane distribution was affected by A197V mutation. CONCLUSIONS The current study is the first to report the functional analysis of SCN1B/ A197V, serving as a substrate responsible for BrS.
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Affiliation(s)
- Linlin Wang
- Department of Cardiology, Nanjing Brain Hospital, The Affiliated Brain Hospital of Nanjing Medical University, Nanjing, People's Republic of China
| | - Zhonglin Han
- Department of Cardiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, People's Republic of China
| | - Jian Dai
- Department of Cardiology, Nanjing Brain Hospital, The Affiliated Brain Hospital of Nanjing Medical University, Nanjing, People's Republic of China
| | - Kejiang Cao
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, People's Republic of China.
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28
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Takla M, Huang CLH, Jeevaratnam K. The cardiac CaMKII-Na v1.5 relationship: From physiology to pathology. J Mol Cell Cardiol 2020; 139:190-200. [PMID: 31958466 DOI: 10.1016/j.yjmcc.2019.12.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 11/20/2019] [Accepted: 12/30/2019] [Indexed: 12/19/2022]
Abstract
The SCN5A gene encodes Nav1.5, which, as the cardiac voltage-gated Na+ channel's pore-forming α subunit, is crucial for the initiation and propagation of atrial and ventricular action potentials. The arrhythmogenic propensity of inherited SCN5A mutations implicates the Na+ channel in determining cardiomyocyte excitability under normal conditions. Cytosolic kinases have long been known to alter the kinetic profile of Nav1.5 inactivation via phosphorylation of specific residues. Recent substantiation of both the role of calmodulin-dependent kinase II (CaMKII) in modulating the properties of the Nav1.5 inactivation gate and the significant rise in oxidation-dependent autonomous CaMKII activity in structural heart disease has raised the possibility of a novel pathway for acquired arrhythmias - the CaMKII-Nav1.5 relationship. The aim of this review is to: (1) outline the relationship's translation from physiological adaptation to pathological vicious circle; and (2) discuss the relative merits of each of its components as pharmacological targets.
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Affiliation(s)
- Michael Takla
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, GU2 7AL, United Kingdom
| | - Christopher L-H Huang
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, GU2 7AL, United Kingdom; Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, CB2 3EG, United Kingdom
| | - Kamalan Jeevaratnam
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, GU2 7AL, United Kingdom; Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, CB2 3EG, United Kingdom.
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29
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Angus M, Ruben P. Voltage gated sodium channels in cancer and their potential mechanisms of action. Channels (Austin) 2019; 13:400-409. [PMID: 31510893 PMCID: PMC6768049 DOI: 10.1080/19336950.2019.1666455] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 08/30/2019] [Accepted: 09/08/2019] [Indexed: 01/22/2023] Open
Abstract
Voltage gated sodium channels (VGSC) are implicated in cancer cell invasion and metastasis. However, the mechanism by which VGSC increase cell invasiveness and probability of metastasis is still unknown. In this review we outline lesser known functions of VGSC outside of action potential propagation, and the current understanding of the effects of VGSC in cancer. Finally, we discuss possible downstream effects of VGSC activation in cancer cells. After extensive review of the literature, the most likely role of VGSC in cancer is in the invadopodia, the leading edge of metastatic cancer cells. Sodium gradients are used to drive many biological processes in the body, and invadopodia may be similar. The function of the sodium hydrogen exchanger (NHE) and sodium calcium exchanger (NCX) are driven by sodium gradients. Voltage gated calcium channels, activated by membrane depolarization, are also capable of becoming activated in response to VGSC activity. Changes to hydrogen ion exchange or calcium handling have functional consequences for invadopodia and would explain the relationship between VGSC expression and invasiveness of cancer cells.
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Affiliation(s)
- Madeline Angus
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - Peter Ruben
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
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30
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Angus M, Peters CH, Poburko D, Brimble E, Spelbrink EM, Ruben PC. Case studies in neuroscience: a novel amino acid duplication in the NH 2-terminus of the brain sodium channel Na V1.1 underlying Dravet syndrome. J Neurophysiol 2019; 122:1975-1980. [PMID: 31533007 DOI: 10.1152/jn.00491.2019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Dravet syndrome is a severe form of childhood epilepsy characterized by frequent temperature-sensitive seizures and delays in cognitive development. In the majority (80%) of cases, Dravet syndrome is caused by mutations in the SCN1A gene, encoding the voltage-gated sodium channel NaV1.1, which is abundant in the central nervous system. Dravet syndrome can be caused by either gain-of-function mutation or loss of function in NaV1.1, making it necessary to characterize each novel mutation. Here we use a combination of patch-clamp recordings and immunocytochemistry to characterize the first known NH2-terminal amino acid duplication mutation found in a patient with Dravet syndrome, M72dup. M72dup does not significantly alter rate of fast inactivation recovery or rate of fast inactivation onset at any measured membrane potential. M72dup significantly shifts the midpoint of the conductance voltage relationship to more hyperpolarized potentials. Most interestingly, M72dup significantly reduces peak current of NaV1.1 and reduces membrane expression. This suggests that M72dup acts as a loss-of-function mutation primarily by impacting the ability of the channel to localize to the plasma membrane.NEW & NOTEWORTHY Genetic screening of a patient with Dravet syndrome revealed a novel mutation in SCN1A. Of over 700 SCN1A mutations known to cause Dravet syndrome, M72dup is the first to be identified in the NH2-terminus of NaV1.1. We studied M72dup using patch-clamp electrophysiology and immunocytochemistry. M72dup causes a decrease in membrane expression of NaV1.1 and overall loss of function, consistent with the role of the NH2-terminal region in membrane trafficking of NaV1.1.
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Affiliation(s)
- Madeline Angus
- Department of Biomedical Physiology, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Colin H Peters
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Damon Poburko
- Department of Biomedical Physiology, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Elise Brimble
- Department of Neurology and Neurological Sciences, Stanford Medicine, Palo Alto, California
| | - Emily M Spelbrink
- Department of Neurology and Neurological Sciences, Stanford Medicine, Palo Alto, California
| | - Peter C Ruben
- Department of Biomedical Physiology, Simon Fraser University, Burnaby, British Columbia, Canada
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31
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Li S, Han J, Guo G, Sun Y, Zhang T, Zhao M, Xu Y, Cui Y, Liu Y, Zhang J. Voltage-gated sodium channels β3 subunit promotes tumorigenesis in hepatocellular carcinoma by facilitating p53 degradation. FEBS Lett 2019; 594:497-508. [PMID: 31626714 DOI: 10.1002/1873-3468.13641] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 10/03/2019] [Accepted: 10/08/2019] [Indexed: 11/08/2022]
Abstract
The voltage-gated sodium channels (VGSCs) are aberrantly expressed in a variety of tumors and play an important role in tumor growth and metastasis. Here, we show that VGSCs auxiliary β3 subunit, encoded by the SCN3B gene, promotes proliferation and suppresses apoptosis in HepG2 cells by promoting p53 degradation. β3 significantly increases HepG2 cell proliferation, promotes tumor growth in mouse xenograft models, and suppresses senescence and apoptosis. We found that β3 knockdown stabilizes p53 protein, leading to potentiation of p53-induced cell cycle arrest, senescence, and apoptosis. Mechanistic studies revealed that β3 could bind to p53, promoting p53 ubiquitination and degradation by stabilizing the p53/MDM2 complex. Our results suggest that β3 is a novel negative regulator of p53 and a potential oncogenic factor.
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Affiliation(s)
- Shuai Li
- School of Life Sciences and Biopharmaceutical Science, Shenyang Pharmaceutical University, China
| | - Jiadi Han
- School of Life Sciences and Biopharmaceutical Science, Shenyang Pharmaceutical University, China
| | - Guili Guo
- School of Life Sciences and Biopharmaceutical Science, Shenyang Pharmaceutical University, China
| | - Yudi Sun
- School of Life Sciences and Biopharmaceutical Science, Shenyang Pharmaceutical University, China
| | - Tingting Zhang
- School of Life Sciences and Biopharmaceutical Science, Shenyang Pharmaceutical University, China
| | - Mingyi Zhao
- School of Life Sciences and Biopharmaceutical Science, Shenyang Pharmaceutical University, China
| | - Yijia Xu
- School of Life Sciences and Biopharmaceutical Science, Shenyang Pharmaceutical University, China
| | - Yong Cui
- School of Medical Devices, Shenyang Pharmaceutical University, China
| | - Yanfeng Liu
- School of Life Sciences and Biopharmaceutical Science, Shenyang Pharmaceutical University, China
| | - Jinghai Zhang
- School of Life Sciences and Biopharmaceutical Science, Shenyang Pharmaceutical University, China.,School of Medical Devices, Shenyang Pharmaceutical University, China
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32
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Lee J, Kim S, Kim HM, Kim HJ, Yu FH. NaV1.6 and NaV1.7 channels are major endogenous voltage-gated sodium channels in ND7/23 cells. PLoS One 2019; 14:e0221156. [PMID: 31419255 PMCID: PMC6697327 DOI: 10.1371/journal.pone.0221156] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 07/31/2019] [Indexed: 01/02/2023] Open
Abstract
ND7/23 cells are gaining traction as a host model to express peripheral sodium channels such as NaV1.8 and NaV1.9 that have been difficult to express in widely utilized heterologous cells, like CHO and HEK293. Use of ND7/23 as a model cell to characterize the properties of sodium channels requires clear understanding of the endogenous ion channels. To define the nature of the background sodium currents in ND7/23 cells, we aimed to comprehensively profile the voltage-gated sodium channel subunits by endpoint and quantitative reverse transcription-PCR and by whole-cell patch clamp electrophysiology. We found that untransfected ND7/23 cells express endogenous peak sodium currents that average -2.12nA (n = 15) and with kinetics typical of fast sodium currents having activation and inactivation completed within few milliseconds. Furthermore, sodium currents were reduced to virtually nil upon exposure to 100nM tetrodotoxin, indicating that ND7/23 cells have essentially null background for tetrodotoxin-resistant (TTX-R) currents. qRT-PCR profiling indicated a major expression of TTX-sensitive (TTX-S) NaV1.6 and NaV1.7 at similar levels and very low expression of TTX-R NaV1.9 transcripts. There was no expression of TTX-R NaV1.8 in ND7/23 cells. There was low expression of NaV1.1, NaV1.2, NaV1.3 and no expression of cardiac or skeletal muscle sodium channels. As for the sodium channel auxiliary subunits, β1 and β3 subunits were expressed, but not the β2 and β4 subunits that covalently associate with the α-subunits. In addition, our results also showed that only the mouse forms of NaV1.6, NaV1.7 and NaV1.9 sodium channels were expressed in ND7/23 cells that was originally generated as a hybridoma of rat embryonic DRG and mouse neuroblastoma cell-line. By molecular profiling of auxiliary β- and principal α-subunits of the voltage gated sodium channel complex, our results define the background sodium channels expressed in ND7/23 cells, and confirm their utility for detailed functional studies of emerging pain channelopathies ascribed to mutations of the TTX-R sodium channels of sensory neurons.
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Affiliation(s)
- Jisoo Lee
- Department of Pharmacology and Dental Therapeutics, Program in Neurobiology, Dental Research Institute, Seoul National University School of Dentistry, Seoul, Republic of Korea
| | - Shinae Kim
- Department of Pharmacology and Dental Therapeutics, Program in Neurobiology, Dental Research Institute, Seoul National University School of Dentistry, Seoul, Republic of Korea
| | - Hye-mi Kim
- Department of Pharmacology and Dental Therapeutics, Program in Neurobiology, Dental Research Institute, Seoul National University School of Dentistry, Seoul, Republic of Korea
| | - Hyun Jeong Kim
- Department of Dental Anesthesiology, Program in Neurobiology, Dental Research Institute, Seoul National University School of Dentistry, Seoul, Republic of Korea
| | - Frank H. Yu
- Department of Pharmacology and Dental Therapeutics, Program in Neurobiology, Dental Research Institute, Seoul National University School of Dentistry, Seoul, Republic of Korea
- * E-mail:
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33
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Hawrysh PJ, Buck LT. Oxygen-sensitive interneurons exhibit increased activity and GABA release during ROS scavenging in the cerebral cortex of the western painted turtle. J Neurophysiol 2019; 122:466-479. [PMID: 31141433 DOI: 10.1152/jn.00104.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The western painted turtle (Chrysemys picta bellii) has the unique ability of surviving several months in the absence of oxygen, which is termed anoxia. One major protective strategy that the turtle employs during anoxia is a reduction in neuronal electrical activity, which may result from a natural reduction in reactive oxygen species (ROS). We previously linked a reduction in ROS levels to an increase in γ-amino butyric acid (GABA) receptor currents. The purpose of this study is to understand how fast-spiking, GABA-releasing neurons respond to reductions in ROS and how this affects GABA release. Using a fluorescence-coupled enzymatic microplate assay for GABA, we found that anoxia, the ROS scavenger N-(2-mercaptopriopionyl)glycine (MPG), or the mitochondria-specific ROS scavenger MitoTEMPO resulted in a 2.5-, 2.0-, and 2.5-fold increase in extracellular GABA concentration, respectively. This phenomenon could be blocked with TTX, indicating that it is activity dependent. Using whole cell patch-clamping techniques, we found that fast-spiking, burst-firing GABAergic turtle neurons increase the duration and number of action potentials per burst by 26% and 42%, respectively, in response to ROS scavenging via MPG. These results suggest that the reduction in mitochondrially produced ROS that occurs during anoxia leads to increased GABA release, which promotes postsynaptic inhibitory activity through activation of GABA receptors.NEW & NOTEWORTHY This is a novel study examining the response of cerebral cortical stellate interneurons to anoxia and mitochondrial reactive oxygen species (ROS) scavenging with MitoTEMPO. Under both conditions burst firing increases in these cells, and we show that extracellular GABA release increases in the presence of the ROS scavenger. We conclude that in the anoxia-tolerant painted turtle brain, a decrease in ROS levels is an important low oxygen signal.
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Affiliation(s)
- Peter John Hawrysh
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Leslie Thomas Buck
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada.,Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
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34
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Meredith FL, Rennie KJ. Regional and Developmental Differences in Na + Currents in Vestibular Primary Afferent Neurons. Front Cell Neurosci 2018; 12:423. [PMID: 30487736 PMCID: PMC6246661 DOI: 10.3389/fncel.2018.00423] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 10/29/2018] [Indexed: 02/04/2023] Open
Abstract
The vestibular system relays information about head position via afferent nerve fibers to the brain in the form of action potentials. Voltage-gated Na+ channels in vestibular afferents drive the initiation and propagation of action potentials, but their expression during postnatal development and their contributions to firing in diverse mature afferent populations are unknown. Electrophysiological techniques were used to determine Na+ channel subunit types in vestibular calyx-bearing afferents at different stages of postnatal development. We used whole cell patch clamp recordings in thin slices of gerbil crista neuroepithelium to investigate Na+ channels and firing patterns in central zone (CZ) and peripheral zone (PZ) afferents. PZ afferents are exclusively dimorphic, innervating type I and type II hair cells, whereas CZ afferents can form dimorphs or calyx-only terminals which innervate type I hair cells alone. All afferents expressed tetrodotoxin (TTX)-sensitive Na+ currents, but TTX-sensitivity varied with age. During the fourth postnatal week, 200–300 nM TTX completely blocked sodium currents in PZ and CZ calyces. By contrast, in immature calyces [postnatal day (P) 5–11], a small component of peak sodium current remained in 200 nM TTX. Application of 1 μM TTX, or Jingzhaotoxin-III plus 200 nM TTX, abolished sodium current in immature calyces, suggesting the transient expression of voltage-gated sodium channel 1.5 (Nav1.5) during development. A similar TTX-insensitive current was found in early postnatal crista hair cells (P5–9) and constituted approximately one third of the total sodium current. The Nav1.6 channel blocker, 4,9-anhydrotetrodotoxin, reduced a component of sodium current in immature and mature calyces. At 100 nM 4,9-anhydrotetrodotoxin, peak sodium current was reduced on average by 20% in P5–14 calyces, by 37% in mature dimorphic PZ calyces, but by less than 15% in mature CZ calyx-only terminals. In mature PZ calyces, action potentials became shorter and broader in the presence of 4,9-anhydrotetrodotoxin implicating a role for Nav1.6 channels in firing in dimorphic afferents.
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Affiliation(s)
- Frances L Meredith
- Department of Otolaryngology, University of Colorado School of Medicine, Aurora, CO, United States
| | - Katherine J Rennie
- Department of Otolaryngology, University of Colorado School of Medicine, Aurora, CO, United States.,Department of Physiology & Biophysics, University of Colorado School of Medicine, Aurora, CO, United States
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Baroni D, Picco C, Moran O. A mutation of SCN1B associated with GEFS+ causes functional and maturation defects of the voltage-dependent sodium channel. Hum Mutat 2018; 39:1402-1415. [PMID: 29992740 DOI: 10.1002/humu.23589] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 06/25/2018] [Accepted: 07/03/2018] [Indexed: 12/19/2022]
Abstract
Voltage-dependent sodium channels are responsible of the rising phase of the action potential in excitable cells. These integral membrane proteins are composed of a pore-forming α-subunit, and one or more auxiliary β subunits. Mutation p.Asp25Asn (D25N; c.73G > A) of the β1 subunit, coded by the gene SCN1B, has been reported in a patient with generalized epilepsy with febrile seizure plus type 1 (GEFS+). In human embryonic kidney 293 (HEK) cells, the heterologous coexpression of D25N-β1 subunit with Nav1.2, Nav1.4, and Nav1.5 α subunits, representative of brain, skeletal muscle, and heart voltage gated sodium channels, determines a reduced sodium channel functional expression and a negative shift of the activation and inactivation steady state curves. The D25N mutation of the β1 subunit causes a maturation (glycosylation) defect of the protein, leading to a reduced targeting to the plasma membrane. Also the β1-dependent gating properties of the sodium channels are abolished by the mutation, suggesting that D25N is no more able to interact with the α subunit. Our work underscores the role played by the β1 subunit, highlighting how a defective interaction between the sodium channel constituents could lead to a disabling pathological condition, and opens the possibility to design a mutation-specific GEFS+ treatment based on protein maturation.
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Calloe K, Aistrup GL, Di Diego JM, Goodrow RJ, Treat JA, Cordeiro JM. Interventricular differences in sodium current and its potential role in Brugada syndrome. Physiol Rep 2018; 6:e13787. [PMID: 30009404 PMCID: PMC6046646 DOI: 10.14814/phy2.13787] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 06/14/2018] [Accepted: 06/15/2018] [Indexed: 12/19/2022] Open
Abstract
Brugada syndrome (BrS) is an inherited disease associated with ST elevation in the right precordial leads, polymorphic ventricular tachycardia (PVT), and sudden cardiac death in adults. Mutations in the cardiac sodium channel account for a large fraction of BrS cases. BrS manifests in the right ventricle (RV), which led us to examine the biophysical and molecular properties of sodium channel in myocytes isolated from the left (LV) and right ventricle. Patch clamp was used to record sodium current (INa ) in single canine RV and LV epicardial (epi) and endocardial (endo) myocytes. Action potentials were recorded from multicellular preparations and single cells. mRNA and proteins were determined using quantitative RT-PCR and Western blot. Although LV wedge preparations were thicker than RV wedges, transmural ECG recordings showed no difference in the width of the QRS complex or transmural conduction time. Action potential characteristics showed RV epi and endo had a lower Vmax compared with LV epi and endo cells. Peak INa density was significantly lower in epi and endo RV cells compared with epi and endo LV cells. Recovery from inactivation of INa in RV cells was slightly faster and half maximal steady-state inactivation was more positive. β2 and β4 mRNA was detected at very low levels in both ventricles, which was confirmed at the protein level. Our observations demonstrate that Vmax and Na+ current are smaller in RV, presumably due to differential Nav 1.5/β subunit expression. These results provide a potential mechanism for the right ventricular manifestation of BrS.
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Affiliation(s)
- Kirstine Calloe
- Department of Veterinary and Animal SciencesSection for Anatomy, Biochemistry and PhysiologyUniversity of CopenhagenFrederiksbergDenmark
| | - Gary L. Aistrup
- Department of Experimental CardiologyMasonic Medical Research LaboratoryUticaNew York
| | - José M. Di Diego
- Department of Experimental CardiologyMasonic Medical Research LaboratoryUticaNew York
- Lankenau Institute for Medical ResearchWynnewoodPennsylvania
| | - Robert J. Goodrow
- Department of Experimental CardiologyMasonic Medical Research LaboratoryUticaNew York
| | - Jacqueline A. Treat
- Department of Experimental CardiologyMasonic Medical Research LaboratoryUticaNew York
| | - Jonathan M. Cordeiro
- Department of Experimental CardiologyMasonic Medical Research LaboratoryUticaNew York
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Körner J, Meents J, Machtens J, Lampert A. β1 subunit stabilises sodium channel Nav1.7 against mechanical stress. J Physiol 2018; 596:2433-2445. [PMID: 29659026 PMCID: PMC6002208 DOI: 10.1113/jp275905] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Accepted: 04/06/2018] [Indexed: 12/19/2022] Open
Abstract
KEY POINTS The voltage-gated sodium channel Nav1.7 is a key player in neuronal excitability and pain signalling. In addition to voltage sensing, the channel is also modulated by mechanical stress. Using whole-cell patch-clamp experiments, we discovered that the sodium channel subunit β1 is able to prevent the impact of mechanical stress on Nav1.7. An intramolecular disulfide bond of β1 was identified to be essential for stabilisation of inactivation, but not activation, against mechanical stress using molecular dynamics simulations, homology modelling and site-directed mutagenesis. Our results highlight the role of segment 6 of domain IV in fast inactivation. We present a candidate mechanism for sodium channel stabilisation against mechanical stress, ensuring reliable channel functionality in living systems. ABSTRACT Voltage-gated sodium channels are key players in neuronal excitability and pain signalling. Precise gating of these channels is crucial as even small functional alterations can lead to pathological phenotypes such as pain or heart failure. Mechanical stress has been shown to affect sodium channel activation and inactivation. This suggests that stabilising components are necessary to ensure precise channel gating in living organisms. Here, we show that mechanical shear stress affects voltage dependence of activation and fast inactivation of the Nav1.7 channel. Co-expression of the β1 subunit, however, protects both gating modes of Nav1.7 against mechanical shear stress. Using molecular dynamics simulation, homology modelling and site-directed mutagenesis, we identify an intramolecular disulfide bond of β1 (Cys21-Cys43) which is partially involved in this process: the β1-C43A mutant prevents mechanical modulation of voltage dependence of activation, but not of fast inactivation. Our data emphasise the unique role of segment 6 of domain IV for sodium channel fast inactivation and confirm previous reports that the intracellular process of fast inactivation can be modified by interfering with the extracellular end of segment 6 of domain IV. Thus, our data suggest that physiological gating of Nav1.7 may be protected against mechanical stress in a living organism by assembly with the β1 subunit.
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Affiliation(s)
- Jannis Körner
- Institute of PhysiologyRWTH Aachen UniversityPauwelsstrasse 30Aachen52074Germany
- Institute of Complex Systems, Zelluläre Biophysik (ICS‐4) and JARA‐HPCForschungszentrum JülichJülichGermany
| | - Jannis Meents
- Institute of PhysiologyRWTH Aachen UniversityPauwelsstrasse 30Aachen52074Germany
| | - Jan‐Philipp Machtens
- Institute of Complex Systems, Zelluläre Biophysik (ICS‐4) and JARA‐HPCForschungszentrum JülichJülichGermany
| | - Angelika Lampert
- Institute of PhysiologyRWTH Aachen UniversityPauwelsstrasse 30Aachen52074Germany
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Molinarolo S, Lee S, Leisle L, Lueck JD, Granata D, Carnevale V, Ahern CA. Cross-kingdom auxiliary subunit modulation of a voltage-gated sodium channel. J Biol Chem 2018; 293:4981-4992. [PMID: 29371400 PMCID: PMC5892571 DOI: 10.1074/jbc.ra117.000852] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 01/17/2018] [Indexed: 02/04/2023] Open
Abstract
Voltage-gated, sodium ion-selective channels (NaV) generate electrical signals contributing to the upstroke of the action potential in animals. NaVs are also found in bacteria and are members of a larger family of tetrameric voltage-gated channels that includes CaVs, KVs, and NaVs. Prokaryotic NaVs likely emerged from a homotetrameric Ca2+-selective voltage-gated progenerator, and later developed Na+ selectivity independently. The NaV signaling complex in eukaryotes contains auxiliary proteins, termed beta (β) subunits, which are potent modulators of the expression profiles and voltage-gated properties of the NaV pore, but it is unknown whether they can functionally interact with prokaryotic NaV channels. Herein, we report that the eukaryotic NaVβ1-subunit isoform interacts with and enhances the surface expression as well as the voltage-dependent gating properties of the bacterial NaV, NaChBac in Xenopus oocytes. A phylogenetic analysis of the β-subunit gene family proteins confirms that these proteins appeared roughly 420 million years ago and that they have no clear homologues in bacterial phyla. However, a comparison between eukaryotic and bacterial NaV structures highlighted the presence of a conserved fold, which could support interactions with the β-subunit. Our electrophysiological, biochemical, structural, and bioinformatics results suggests that the prerequisites for β-subunit regulation are an evolutionarily stable and intrinsic property of some voltage-gated channels.
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Affiliation(s)
- Steven Molinarolo
- From the Department of Molecular Physiology and Biophysics, Carver College of Medicine, Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa 52242
| | - Sora Lee
- the Weill Cornell Medical College, Cornell University, New York, New York 10065, and
| | - Lilia Leisle
- the Weill Cornell Medical College, Cornell University, New York, New York 10065, and
| | - John D Lueck
- From the Department of Molecular Physiology and Biophysics, Carver College of Medicine, Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa 52242
| | - Daniele Granata
- the Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania 19122
| | - Vincenzo Carnevale
- the Institute for Computational Molecular Science, Temple University, Philadelphia, Pennsylvania 19122
| | - Christopher A Ahern
- From the Department of Molecular Physiology and Biophysics, Carver College of Medicine, Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa 52242,
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Biophysical comparison of sodium currents in native cardiac myocytes and human induced pluripotent stem cell-derived cardiomyocytes. J Pharmacol Toxicol Methods 2017; 90:19-30. [PMID: 29128504 DOI: 10.1016/j.vascn.2017.11.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 09/22/2017] [Accepted: 11/02/2017] [Indexed: 12/31/2022]
Abstract
INTRODUCTION Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are used for safety pharmacology and to investigate genetic diseases affecting cardiac ion channels. It is unclear whether adult myocytes or hiPSC-CMs are the better platform for cardiac safety pharmacology. We examined the biophysical and molecular properties of INa in adult myocytes and hiPSC-CMs. METHODS hiPSC-CMs were plated at low density. Atrial and ventricular cells were obtained from dog hearts. Whole cell patch clamp was used to record INa. RESULTS Voltage clamp recordings showed a large INa in all three cell types but different densities. Small differences in steady-state inactivation and recovery from inactivation were noted in the three cell types. Application of lidocaine to the three cell types showed a similar pattern of block of INa under voltage clamp; however, lidocaine produced different effects on AP waveform under current clamp. AP clamp experiments showed that application of ventricular or atrial cell waveforms to the same hiPSC-CM elicited a large INa while application of a sinoatrial node waveform elicited no INa. Molecular analysis of Na+ channel subunits showed SCN5A and SCN1B-4B were expressed in adult cells and iPSC-CMs. However, iPSC-CMs express both fetal (exon 6A) and adult (exon 6) isoforms of SCN5A. DISCUSSION There are major differences in INa density and smaller differences in other biophysical properties of INa in adult atrial, ventricular, and hiPSC-CMs. The depolarized maximum diastolic potential coupled with the presence of phase 4 depolarization limits the contribution of INa in hiPSC-CM action potentials. Our results suggest that hiPSC-CMs may be useful for drug screening of Na+ channel inhibitors under voltage clamp but not current clamp.
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Wang J, Ou SW, Wang YJ. Distribution and function of voltage-gated sodium channels in the nervous system. Channels (Austin) 2017; 11:534-554. [PMID: 28922053 DOI: 10.1080/19336950.2017.1380758] [Citation(s) in RCA: 87] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Voltage-gated sodium channels (VGSCs) are the basic ion channels for neuronal excitability, which are crucial for the resting potential and the generation and propagation of action potentials in neurons. To date, at least nine distinct sodium channel isoforms have been detected in the nervous system. Recent studies have identified that voltage-gated sodium channels not only play an essential role in the normal electrophysiological activities of neurons but also have a close relationship with neurological diseases. In this study, the latest research findings regarding the structure, type, distribution, and function of VGSCs in the nervous system and their relationship to neurological diseases, such as epilepsy, neuropathic pain, brain tumors, neural trauma, and multiple sclerosis, are reviewed in detail.
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Affiliation(s)
- Jun Wang
- a Department of Neurosurgery , The First Hospital of China Medical University , Shenyang , P.R. China
| | - Shao-Wu Ou
- a Department of Neurosurgery , The First Hospital of China Medical University , Shenyang , P.R. China
| | - Yun-Jie Wang
- a Department of Neurosurgery , The First Hospital of China Medical University , Shenyang , P.R. China
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Mutation E87Q of the β1-subunit impairs the maturation of the cardiac voltage-dependent sodium channel. Sci Rep 2017; 7:10683. [PMID: 28878239 PMCID: PMC5587543 DOI: 10.1038/s41598-017-10645-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 08/11/2017] [Indexed: 12/19/2022] Open
Abstract
Voltage-dependent sodium channels are responsible of the rising phase of the action potential in excitable cells. These membrane integral proteins are composed by a pore-forming α-subunit, and one or more auxiliary β subunits. Mutation E87Q of the β1 subunit is correlated with Brugada syndrome, a genetic disease characterised by ventricular fibrillation, right precordial ST segment elevation on ECG and sudden cardiac death. Heterologous expression of E87Q-β1 subunit in CHO cells determines a reduced sodium channel functional expression. The effect the E87Q mutation of the β1 subunit on sodium currents and α protein expression is correlated with a reduced availability of the mature form of the α subunit in the plasma membrane. This finding offers a new target for the treatment of the Brugada syndrome, based on protein maturation management. This work highlights the role played by the β1 subunit in the maturation and expression of the entire sodium channel complex and underlines how the defective interaction between the sodium channel constituents could lead to a disabling pathological condition.
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42
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Wu Y, Ai M, Bardeesi ASA, Xu L, Zheng J, Zheng D, Yin K, Wu Q, Zhang L, Huang L, Cheng J. Brugada syndrome: a fatal disease with complex genetic etiologies - still a long way to go. Forensic Sci Res 2017; 2:115-125. [PMID: 30483629 PMCID: PMC6197104 DOI: 10.1080/20961790.2017.1333203] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2016] [Accepted: 05/04/2017] [Indexed: 12/19/2022] Open
Abstract
Brugada syndrome (BrS) is an arrhythmogenic disorder which was first described in 1992. This disease is a channelopathy characterized by ST-segment elevations in the right precordial leads and is susceptible to sudden death. BrS is a fatal disease with gender and age preferences. It occurs mainly in young male subjects with a structurally normal heart and silently progresses to sudden death with no significant symptoms. The prevalence of BrS has been reported in the ranges of 5–20 per 10 000 people. The disease is more prevalent in Asia. Nowadays, numerous variations in 23 genes have been linked to BrS since the first gene SCN5A has been associated with BrS in 1998. Not only can clinical specialists apply these discoveries in risk assessment, diagnosis and personal medicine, but also forensic pathologists can make full use of these variations to conduct death cause identification. However, despite the progress in genetics, these associated genes can only account for approximately 35% of the BrS cases while the etiology of the remaining BrS cases is still unexplained. In this review, we discussed the prevalence, the genes associated with BrS and the application of molecular autopsy in forensic pathology. We also summarized the present obstacles, and provided a new insight into the genetic basis of BrS.
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Affiliation(s)
- Yeda Wu
- Department of Forensic Pathology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Mei Ai
- Forensic Science Center of WASTON Guangdong Province, Guangzhou, China
| | - Adham Sameer A Bardeesi
- Department of Forensic Pathology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Lunwu Xu
- The Branch Office of Yanping, Public Security Bureau of Nanping, Nanping, China
| | - Jingjing Zheng
- Department of Forensic Pathology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Da Zheng
- Department of Forensic Pathology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Kun Yin
- Department of Forensic Pathology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Qiuping Wu
- Department of Forensic Pathology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Liyong Zhang
- Department of Forensic Pathology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Lei Huang
- Department of Forensic Pathology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Jianding Cheng
- Department of Forensic Pathology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
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Cardoso FC, Dekan Z, Smith JJ, Deuis JR, Vetter I, Herzig V, Alewood PF, King GF, Lewis RJ. Modulatory features of the novel spider toxin μ-TRTX-Df1a isolated from the venom of the spider Davus fasciatus. Br J Pharmacol 2017; 174:2528-2544. [PMID: 28542706 DOI: 10.1111/bph.13865] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2016] [Revised: 05/01/2017] [Accepted: 05/02/2017] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND AND PURPOSE Naturally occurring dysfunction of voltage-gated sodium (NaV ) channels results in complex disorders such as chronic pain, making these channels an attractive target for new therapies. In the pursuit of novel NaV modulators, we investigated spider venoms for new inhibitors of NaV channels. EXPERIMENTAL APPROACH We used high-throughput screens to identify a NaV modulator in venom of the spider Davus fasciatus. Further characterization of this venom peptide was undertaken using fluorescent and electrophysiological assays, molecular modelling and a rodent pain model. KEY RESULTS We identified a potent NaV inhibitor named μ-TRTX-Df1a. This 34-residue peptide fully inhibited responses mediated by NaV 1.7 endogenously expressed in SH-SY5Y cells. Df1a also inhibited voltage-gated calcium (CaV 3) currents but had no activity against the voltage-gated potassium (KV 2) channel. The modelled structure of Df1a, which contains an inhibitor cystine knot motif, is reminiscent of the NaV channel toxin ProTx-I. Electrophysiology revealed that Df1a inhibits all NaV subtypes tested (hNaV 1.1-1.7). Df1a also slowed fast inactivation of NaV 1.1, NaV 1.3 and NaV 1.5 and modified the voltage-dependence of activation and inactivation of most of the NaV subtypes. Df1a preferentially binds to the domain II voltage-sensor and has additional interactions with the voltage sensors domains III and IV, which probably explains its modulatory features. Df1a was analgesic in vivo, reversing the spontaneous pain behaviours induced by the NaV activator OD1. CONCLUSION AND IMPLICATIONS μ-TRTX-Df1a shows potential as a new molecule for the development of drugs to treat pain disorders mediated by voltage-gated ion channels.
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Affiliation(s)
- Fernanda C Cardoso
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, Australia
| | - Zoltan Dekan
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, Australia
| | - Jennifer J Smith
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, Australia
| | - Jennifer R Deuis
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, Australia.,School of Pharmacy, The University of Queensland, Woolloongabba, QLD, Australia
| | - Irina Vetter
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, Australia.,School of Pharmacy, The University of Queensland, Woolloongabba, QLD, Australia
| | - Volker Herzig
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, Australia
| | - Paul F Alewood
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, Australia
| | - Glenn F King
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, Australia
| | - Richard J Lewis
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, Australia
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Soderlund DM, Tan J, He B. Functional reconstitution of rat Na v1.6 sodium channels in vitro for studies of pyrethroid action. Neurotoxicology 2017; 60:142-149. [PMID: 27013268 PMCID: PMC5031521 DOI: 10.1016/j.neuro.2016.03.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 03/17/2016] [Accepted: 03/17/2016] [Indexed: 01/14/2023]
Abstract
The ability to reconstitute sodium channel function and pharmacology in vitro using cloned subunits of known structure has greatly enhanced our understanding of the action of pyrethroid insecticides at this target and the structural determinants of resistance and interspecies selectivity. However, the use of reconstituted channels raises three critical questions: (1) Which subunits and subunit combinations should be used? (2) Which heterologous expression system is preferred? (3) Which combination of subunits and expression system best represents the function of native neuronal channels in the organism of interest? This review considers these questions from the perspective of recent research in this laboratory on the action of pyrethroid insecticides on rat Nav1.6 sodium channels by comparing the effects of heteroligomeric complex composition on channel function and insecticide response when channels are expressed in either Xenopus oocytes or stably-transformed HEK293 cells. These comparisons provide new insight into the influence of cellular context on the functional and pharmacological properties of expressed channels, the modulatory effects of sodium channel auxiliary subunits on the action of pyrethroids, and the relative fidelity of the Xenopus oocyte and HEK293 cell expression systems as model systems for studying of channel function and pyrethroid action.
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Affiliation(s)
- David M Soderlund
- Department of Entomology, Cornell University, Geneva, NY 14456, USA.
| | | | - Bingjun He
- College of Life Sciences, Nankai University, Tianjin 300071, China
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45
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Magby JP, Richardson JR. Developmental pyrethroid exposure causes long-term decreases of neuronal sodium channel expression. Neurotoxicology 2017; 60:274-279. [DOI: 10.1016/j.neuro.2016.04.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Revised: 03/24/2016] [Accepted: 04/01/2016] [Indexed: 10/22/2022]
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46
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Barajas-Martinez H, Goodrow RJ, Hu D, Patel P, Desai M, Panama BK, Treat JA, Aistrup GL, Cordeiro JM. Biophysical and molecular comparison of sodium current in cells isolated from canine atria and pulmonary vein. Pflugers Arch 2017; 469:703-712. [PMID: 28243733 DOI: 10.1007/s00424-017-1956-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 02/08/2017] [Accepted: 02/10/2017] [Indexed: 11/25/2022]
Abstract
The collar of the pulmonary vein (PV) is the focal point for the initiation of atrial arrhythmias, but the mechanisms underlying how PV cells differ from neighboring left atrial tissue are unclear. We examined the biophysical and molecular properties of INa in cells isolated from the canine pulmonary sleeve and compared the properties to left atrial tissue. PV and left atrial myocytes were isolated and patch clamp techniques were used to record INa. Action potential recordings from either tissue type were made using high-resistance electrodes. mRNA was determined using quantitative RT-PCR and proteins were determined by Western blot. Analysis of the action potential characteristics showed that PV tissue had a lower Vmax compared with left atrial tissue. Fast INa showed that current density was slightly lower in PV cells compared with LA cells (-96 ± 18.7 pA/pF vs. -120 ± 6.7 pA/pF, respectively, p < 0.05). The recovery from inactivation of INa in PV cells was slightly slower but no marked difference in steady-state inactivation was noted. Analysis of late INa during a 225-ms pulse showed that late INa was significantly smaller in PV cells compared to LA cells at all measured time points into the pulse. These results suggest PV cells have lower density of both peak and late INa. Molecular analysis of Nav1.5 and the four beta subunits showed lower levels of Nav1.5 as well as Navβ1 subunits, confirming the biophysical findings. These data show that a lower density of INa may lead to depression of excitability and predispose the PV collar to re-entrant circuits under pathophysiological conditions.
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Affiliation(s)
- Hector Barajas-Martinez
- Department of Experimental Cardiology, Masonic Medical Research Laboratory, 2150 Bleecker Street, Utica, NY, 13501, USA
| | - Robert J Goodrow
- Department of Experimental Cardiology, Masonic Medical Research Laboratory, 2150 Bleecker Street, Utica, NY, 13501, USA
| | - Dan Hu
- Department of Experimental Cardiology, Masonic Medical Research Laboratory, 2150 Bleecker Street, Utica, NY, 13501, USA
| | - Payal Patel
- Department of Experimental Cardiology, Masonic Medical Research Laboratory, 2150 Bleecker Street, Utica, NY, 13501, USA
| | - Mayurika Desai
- Department of Experimental Cardiology, Masonic Medical Research Laboratory, 2150 Bleecker Street, Utica, NY, 13501, USA
| | - Brian K Panama
- Department of Experimental Cardiology, Masonic Medical Research Laboratory, 2150 Bleecker Street, Utica, NY, 13501, USA
| | - Jacqueline A Treat
- Department of Experimental Cardiology, Masonic Medical Research Laboratory, 2150 Bleecker Street, Utica, NY, 13501, USA
| | - Gary L Aistrup
- Department of Experimental Cardiology, Masonic Medical Research Laboratory, 2150 Bleecker Street, Utica, NY, 13501, USA
| | - Jonathan M Cordeiro
- Department of Experimental Cardiology, Masonic Medical Research Laboratory, 2150 Bleecker Street, Utica, NY, 13501, USA.
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47
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Molinarolo S, Granata D, Carnevale V, Ahern CA. Mining Protein Evolution for Insights into Mechanisms of Voltage-Dependent Sodium Channel Auxiliary Subunits. Handb Exp Pharmacol 2017; 246:33-49. [PMID: 29464397 DOI: 10.1007/164_2017_75] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Voltage-gated sodium channel (VGSC) beta (β) subunits have been called the "overachieving" auxiliary ion channel subunit. Indeed, these subunits regulate the trafficking of the sodium channel complex at the plasma membrane and simultaneously tune the voltage-dependent properties of the pore-forming alpha-subunit. It is now known that VGSC β-subunits are capable of similar modulation of multiple isoforms of related voltage-gated potassium channels, suggesting that their abilities extend into the broader voltage-gated channels. The gene family for these single transmembrane immunoglobulin beta-fold proteins extends well beyond the traditional VGSC β1-β4 subunit designation, with deep roots into the cell adhesion protein family and myelin-related proteins - where inherited mutations result in a myriad of electrical signaling disorders. Yet, very little is known about how VGSC β-subunits support protein trafficking pathways, the basis for their modulation of voltage-dependent gating, and, ultimately, their role in shaping neuronal excitability. An evolutionary approach can be useful in yielding new clues to such functions as it provides an unbiased assessment of protein residues, folds, and functions. An approach is described here which indicates the greater emergence of the modern β-subunits roughly 400 million years ago in the early neurons of Bilateria and bony fish, and the unexpected presence of distant homologues in bacteriophages. Recent structural breakthroughs containing α and β eukaryotic sodium channels containing subunits suggest a novel role for a highly conserved polar contact that occurs within the transmembrane segments. Overall, a mixture of approaches will ultimately advance our understanding of the mechanism for β-subunit interactions with voltage-sensor containing ion channels and membrane proteins.
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Affiliation(s)
- Steven Molinarolo
- Department of Molecular Physiology and Biophysics, Iowa Neuroscience Institute, University of Iowa, Iowa City, IA, USA
| | - Daniele Granata
- Institute for Computational Molecular Science, College of Science and Technology, Temple University, Philadelphia, PA, USA
| | - Vincenzo Carnevale
- Institute for Computational Molecular Science, College of Science and Technology, Temple University, Philadelphia, PA, USA.
| | - Christopher A Ahern
- Department of Molecular Physiology and Biophysics, Iowa Neuroscience Institute, University of Iowa, Iowa City, IA, USA.
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48
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Abstract
Cardiac arrhythmias can follow disruption of the normal cellular electrophysiological processes underlying excitable activity and their tissue propagation as coherent wavefronts from the primary sinoatrial node pacemaker, through the atria, conducting structures and ventricular myocardium. These physiological events are driven by interacting, voltage-dependent, processes of activation, inactivation, and recovery in the ion channels present in cardiomyocyte membranes. Generation and conduction of these events are further modulated by intracellular Ca2+ homeostasis, and metabolic and structural change. This review describes experimental studies on murine models for known clinical arrhythmic conditions in which these mechanisms were modified by genetic, physiological, or pharmacological manipulation. These exemplars yielded molecular, physiological, and structural phenotypes often directly translatable to their corresponding clinical conditions, which could be investigated at the molecular, cellular, tissue, organ, and whole animal levels. Arrhythmogenesis could be explored during normal pacing activity, regular stimulation, following imposed extra-stimuli, or during progressively incremented steady pacing frequencies. Arrhythmic substrate was identified with temporal and spatial functional heterogeneities predisposing to reentrant excitation phenomena. These could arise from abnormalities in cardiac pacing function, tissue electrical connectivity, and cellular excitation and recovery. Triggering events during or following recovery from action potential excitation could thereby lead to sustained arrhythmia. These surface membrane processes were modified by alterations in cellular Ca2+ homeostasis and energetics, as well as cellular and tissue structural change. Study of murine systems thus offers major insights into both our understanding of normal cardiac activity and its propagation, and their relationship to mechanisms generating clinical arrhythmias.
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Affiliation(s)
- Christopher L-H Huang
- Physiological Laboratory and the Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
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49
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Bon E, Driffort V, Gradek F, Martinez-Caceres C, Anchelin M, Pelegrin P, Cayuela ML, Marionneau-Lambot S, Oullier T, Guibon R, Fromont G, Gutierrez-Pajares JL, Domingo I, Piver E, Moreau A, Burlaud-Gaillard J, Frank PG, Chevalier S, Besson P, Roger S. SCN4B acts as a metastasis-suppressor gene preventing hyperactivation of cell migration in breast cancer. Nat Commun 2016; 7:13648. [PMID: 27917859 PMCID: PMC5150224 DOI: 10.1038/ncomms13648] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Accepted: 10/20/2016] [Indexed: 12/19/2022] Open
Abstract
The development of metastases largely relies on the capacity of cancer cells to invade extracellular matrices (ECM) using two invasion modes termed ‘mesenchymal' and ‘amoeboid', with possible transitions between these modes. Here we show that the SCN4B gene, encoding for the β4 protein, initially characterized as an auxiliary subunit of voltage-gated sodium channels (NaV) in excitable tissues, is expressed in normal epithelial cells and that reduced β4 protein levels in breast cancer biopsies correlate with high-grade primary and metastatic tumours. In cancer cells, reducing β4 expression increases RhoA activity, potentiates cell migration and invasiveness, primary tumour growth and metastatic spreading, by promoting the acquisition of an amoeboid–mesenchymal hybrid phenotype. This hyperactivated migration is independent of NaV and is prevented by overexpression of the intracellular C-terminus of β4. Conversely, SCN4B overexpression reduces cancer cell invasiveness and tumour progression, indicating that SCN4B/β4 represents a metastasis-suppressor gene. The capacity of cancer cells to migrate is intimately linked to their ability to induce metastasis. Here the authors show that the sodium channel β4 subunit regulates breast cancer cell migration via inhibition of RhoA activation, independently from its function as an auxiliary protein of the sodium channel.
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Affiliation(s)
- Emeline Bon
- Inserm UMR1069, Nutrition, Croissance et Cancer, Université François-Rabelais de Tours, 10 Boulevard Tonnellé, 37032 Tours, France
| | - Virginie Driffort
- Inserm UMR1069, Nutrition, Croissance et Cancer, Université François-Rabelais de Tours, 10 Boulevard Tonnellé, 37032 Tours, France
| | - Frédéric Gradek
- Inserm UMR1069, Nutrition, Croissance et Cancer, Université François-Rabelais de Tours, 10 Boulevard Tonnellé, 37032 Tours, France
| | - Carlos Martinez-Caceres
- Inflammation and Experimental Surgery Unit, CIBERehd, Murcia's BioHealth Research Institute IMIB-Arrixaca, Clinical University Hospital Virgen de la Arrixaca, E-30120 Murcia, Spain
| | - Monique Anchelin
- Telomerase, Cancer and Aging Group, Hospital Virgen de la Arrixaca, E-30120 Murcia, Spain
| | - Pablo Pelegrin
- Inflammation and Experimental Surgery Unit, CIBERehd, Murcia's BioHealth Research Institute IMIB-Arrixaca, Clinical University Hospital Virgen de la Arrixaca, E-30120 Murcia, Spain
| | - Maria-Luisa Cayuela
- Telomerase, Cancer and Aging Group, Hospital Virgen de la Arrixaca, E-30120 Murcia, Spain
| | | | - Thibauld Oullier
- Cancéropôle du Grand Ouest, Plateforme In Vivo, 44000 Nantes, France
| | - Roseline Guibon
- Inserm UMR1069, Nutrition, Croissance et Cancer, Université François-Rabelais de Tours, 10 Boulevard Tonnellé, 37032 Tours, France.,CHRU de Tours, 2 Boulevard Tonnellé, 37000 Tours, France
| | - Gaëlle Fromont
- Inserm UMR1069, Nutrition, Croissance et Cancer, Université François-Rabelais de Tours, 10 Boulevard Tonnellé, 37032 Tours, France.,CHRU de Tours, 2 Boulevard Tonnellé, 37000 Tours, France
| | - Jorge L Gutierrez-Pajares
- Inserm UMR1069, Nutrition, Croissance et Cancer, Université François-Rabelais de Tours, 10 Boulevard Tonnellé, 37032 Tours, France
| | - Isabelle Domingo
- Inserm UMR1069, Nutrition, Croissance et Cancer, Université François-Rabelais de Tours, 10 Boulevard Tonnellé, 37032 Tours, France
| | - Eric Piver
- CHRU de Tours, 2 Boulevard Tonnellé, 37000 Tours, France.,Inserm, U966, Université François-Rabelais de Tours, 10 Boulevard Tonnellé, 37032 Tours, France
| | - Alain Moreau
- Inserm, U966, Université François-Rabelais de Tours, 10 Boulevard Tonnellé, 37032 Tours, France
| | - Julien Burlaud-Gaillard
- Laboratoire de Biologie Cellulaire-Microscopie Electronique, Faculté de Médecine, Université François-Rabelais de Tours, 2 Boulevard Tonnellé, 37000 Tours, France
| | - Philippe G Frank
- Inserm UMR1069, Nutrition, Croissance et Cancer, Université François-Rabelais de Tours, 10 Boulevard Tonnellé, 37032 Tours, France
| | - Stéphan Chevalier
- Inserm UMR1069, Nutrition, Croissance et Cancer, Université François-Rabelais de Tours, 10 Boulevard Tonnellé, 37032 Tours, France.,UFR Sciences Pharmaceutiques, Université François-Rabelais de Tours, 31 Avenue Monge, 37200 Tours, France
| | - Pierre Besson
- Inserm UMR1069, Nutrition, Croissance et Cancer, Université François-Rabelais de Tours, 10 Boulevard Tonnellé, 37032 Tours, France.,UFR Sciences Pharmaceutiques, Université François-Rabelais de Tours, 31 Avenue Monge, 37200 Tours, France
| | - Sébastien Roger
- Inserm UMR1069, Nutrition, Croissance et Cancer, Université François-Rabelais de Tours, 10 Boulevard Tonnellé, 37032 Tours, France.,UFR Sciences et Techniques, Département de Physiologie Animale, Université François-Rabelais de Tours, Parc de Grandmont, 37200 Tours, France.,Institut Universitaire de France, 1, Rue Descartes, 75231 Paris Cedex 05, France
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50
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Masocha W. Gene expression profile of sodium channel subunits in the anterior cingulate cortex during experimental paclitaxel-induced neuropathic pain in mice. PeerJ 2016; 4:e2702. [PMID: 27896032 PMCID: PMC5119229 DOI: 10.7717/peerj.2702] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Accepted: 10/19/2016] [Indexed: 12/19/2022] Open
Abstract
Paclitaxel, a chemotherapeutic agent, causes neuropathic pain whose supraspinal pathophysiology is not fully understood. Dysregulation of sodium channel expression, studied mainly in the periphery and spinal cord level, contributes to the pathogenesis of neuropathic pain. We examined gene expression of sodium channel (Nav) subunits by real time polymerase chain reaction (PCR) in the anterior cingulate cortex (ACC) at day 7 post first administration of paclitaxel, when mice had developed paclitaxel-induced thermal hyperalgesia. The ACC was chosen because increased activity in the ACC has been observed during neuropathic pain. In the ACC of vehicle-treated animals the threshold cycle (Ct) values for Nav1.4, Nav1.5, Nav1.7, Nav1.8 and Nav1.9 were above 30 and/or not detectable in some samples. Thus, comparison in mRNA expression between untreated control, vehicle-treated and paclitaxel treated animals was done for Nav1.1, Nav1.2, Nav1.3, Nav1.6, Nax as well as Navβ1–Navβ4. There were no differences in the transcript levels of Nav1.1–Nav1.3, Nav1.6, Nax, Navβ1–Navβ3 between untreated and vehicle-treated mice, however, vehicle treatment increased Navβ4 expression. Paclitaxel treatment significantly increased the mRNA expression of Nav1.1, Nav1.2, Nav1.6 and Nax, but not Nav1.3, sodium channel alpha subunits compared to vehicle-treated animals. Treatment with paclitaxel significantly increased the expression of Navβ1 and Navβ3, but not Navβ2 and Navβ4, sodium channel beta subunits compared to vehicle-treated animals. These findings suggest that during paclitaxel-induced neuropathic pain (PINP) there is differential upregulation of sodium channels in the ACC, which might contribute to the increased neuronal activity observed in the area during neuropathic pain.
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Affiliation(s)
- Willias Masocha
- Department of Pharmacology and Therapeutics, Faculty of Pharmacy, Kuwait University , Safat , Kuwait
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