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Keleş D, Sipahi M, İnanç-Sürer Ş, Djamgoz MB, Oktay G. Tetracaine downregulates matrix metalloproteinase activity and inhibits invasiveness of strongly metastatic MDA-MB-231 human breast cancer cells. Chem Biol Interact 2023; 385:110730. [PMID: 37806380 DOI: 10.1016/j.cbi.2023.110730] [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: 06/10/2023] [Revised: 09/19/2023] [Accepted: 09/25/2023] [Indexed: 10/10/2023]
Abstract
Tetracaine, a long-acting amino ester-type local anesthetic, prevents the initiation and propagation of action potentials by reversibly blocking voltage-gated sodium channels (VGSCs). These channels, which are highly expressed in several carcinomas (e.g. breast, prostate, colon and lung cancers) have been implicated in promoting metastatic behaviours. Recent evidence suggests that local anesthetics can suppress cancer progression. In this paper, we aimed to explore whether tetracaine would reduce the invasive characteristics of breast cancer cells. In a comparative approach, we used two cell lines of contracting metastatic potential: MDA-MB-231 (strongly metastatic) and MCF-7 (weakly metastatic). Tetracaine (50 μM and 75 μM) did not affect the proliferation of both MDA-MB-231 and MCF-7 cells. Importantly, tetracaine suppressed the migratory, invasive, and adhesive capacities of MDA-MB-231 cells; there was no effect on the motility of MCF-7 cells. Tetracaine treatment also significantly decreased the expression and activity levels of MMP-2 and MMP-9, whilst increasing TIMP-2 expression in MDA-MB-231 cells. On the other hand, VGSC α/Nav1.5 and VGSC-β1 mRNA and protein expression levels were not affected. We conclude that tetracaine has anti-invasive effects on breast cancer cells and may be exploited clinically, for example, in surgery and/or in combination therapies.
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Affiliation(s)
- Didem Keleş
- Izmir University of Economics, Vocational School of Health Services, Medical Laboratory Techniques, 35330, Balcova, Izmir, Turkey; Dokuz Eylül University, School of Medicine, Department of Medical Biochemistry, 35340, Inciralti, Izmir, Turkey
| | - Murat Sipahi
- Dokuz Eylül University, School of Medicine, Department of Medical Biochemistry, 35340, Inciralti, Izmir, Turkey
| | - Şeniz İnanç-Sürer
- Dokuz Eylül University, School of Medicine, Department of Medical Biochemistry, 35340, Inciralti, Izmir, Turkey
| | - Mustafa Ba Djamgoz
- Imperial College London, Department of Life Sciences, South Kensington Campus, SW7 2AZ, London, UK; Biotechnology Research Centre, Cyprus International University, Haspolat, Nicosia, TRNC, Mersin 10, Turkey
| | - Gülgün Oktay
- Dokuz Eylül University, School of Medicine, Department of Medical Biochemistry, 35340, Inciralti, Izmir, Turkey.
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2
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Remme CA. SCN5A channelopathy: arrhythmia, cardiomyopathy, epilepsy and beyond. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220164. [PMID: 37122208 PMCID: PMC10150216 DOI: 10.1098/rstb.2022.0164] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Accepted: 12/31/2022] [Indexed: 05/02/2023] Open
Abstract
Influx of sodium ions through voltage-gated sodium channels in cardiomyocytes is essential for proper electrical conduction within the heart. Both acquired conditions associated with sodium channel dysfunction (myocardial ischaemia, heart failure) as well as inherited disorders secondary to mutations in the gene SCN5A encoding for the cardiac sodium channel Nav1.5 are associated with life-threatening arrhythmias. Research in the last decade has uncovered the complex nature of Nav1.5 distribution, function, in particular within distinct subcellular subdomains of cardiomyocytes. Nav1.5-based channels furthermore display previously unrecognized non-electrogenic actions and may impact on cardiac structural integrity, leading to cardiomyopathy. Moreover, SCN5A and Nav1.5 are expressed in cell types other than cardiomyocytes as well as various extracardiac tissues, where their functional role in, e.g. epilepsy, gastrointestinal motility, cancer and the innate immune response is increasingly investigated and recognized. This review provides an overview of these novel insights and how they deepen our mechanistic knowledge on SCN5A channelopathies and Nav1.5 (dys)function. This article is part of the theme issue 'The heartbeat: its molecular basis and physiological mechanisms'.
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Affiliation(s)
- Carol Ann Remme
- Department of Experimental Cardiology, Heart Centre, Amsterdam Cardiovascular Sciences, Heart Failure & Arrhythmias, Amsterdam UMC location AMC, University of Amsterdam, Amsterdam, The Netherlands
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3
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Park J, Proux C, Ehanno W, Réthoré L, Vessières E, Bourreau J, Favre J, Kauffenstein G, Mattei C, Tricoire-Leignel H, Henrion D, Legendre C, Legros C. Tetrodotoxin Decreases the Contractility of Mesenteric Arteries, Revealing the Contribution of Voltage-Gated Na + Channels in Vascular Tone Regulation. Mar Drugs 2023; 21:md21030196. [PMID: 36976245 PMCID: PMC10059581 DOI: 10.3390/md21030196] [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: 02/21/2023] [Revised: 03/11/2023] [Accepted: 03/20/2023] [Indexed: 03/29/2023] Open
Abstract
Tetrodotoxin (TTX) poisoning through the consumption of contaminated fish leads to lethal symptoms, including severe hypotension. This TTX-induced hypotension is likely due to the downfall of peripheral arterial resistance through direct or indirect effects on adrenergic signaling. TTX is a high-affinity blocker of voltage-gated Na+ (NaV) channels. In arteries, NaV channels are expressed in sympathetic nerve endings, both in the intima and media. In this present work, we aimed to decipher the role of NaV channels in vascular tone using TTX. We first characterized the expression of NaV channels in the aorta, a model of conduction arteries, and in mesenteric arteries (MA), a model of resistance arteries, in C57Bl/6J mice, by Western blot, immunochemistry, and absolute RT-qPCR. Our data showed that these channels are expressed in both endothelium and media of aorta and MA, in which scn2a and scn1b were the most abundant transcripts, suggesting that murine vascular NaV channels consist of NaV1.2 channel subtype with NaVβ1 auxiliary subunit. Using myography, we showed that TTX (1 µM) induced complete vasorelaxation in MA in the presence of veratridine and cocktails of antagonists (prazosin and atropine with or without suramin) that suppressed the effects of neurotransmitter release. In addition, TTX (1 µM) strongly potentiated the flow-mediated dilation response of isolated MA. Altogether, our data showed that TTX blocks NaV channels in resistance arteries and consecutively decreases vascular tone. This could explain the drop in total peripheral resistance observed during mammal tetrodotoxications.
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Affiliation(s)
- Joohee Park
- INSERM, CNRS, MITOVASC, Equipe CarME, SFR ICAT, University Angers, 49000 Angers, France
| | - Coralyne Proux
- INSERM, CNRS, MITOVASC, Equipe CarME, SFR ICAT, University Angers, 49000 Angers, France
| | - William Ehanno
- INSERM, CNRS, MITOVASC, Equipe CarME, SFR ICAT, University Angers, 49000 Angers, France
| | - Léa Réthoré
- INSERM, CNRS, MITOVASC, Equipe CarME, SFR ICAT, University Angers, 49000 Angers, France
| | - Emilie Vessières
- INSERM, CNRS, MITOVASC, Equipe CarME, SFR ICAT, University Angers, 49000 Angers, France
| | - Jennifer Bourreau
- INSERM, CNRS, MITOVASC, Equipe CarME, SFR ICAT, University Angers, 49000 Angers, France
| | - Julie Favre
- INSERM, CNRS, MITOVASC, Equipe CarME, SFR ICAT, University Angers, 49000 Angers, France
- UMR INSERM 1121, CRBS, Strasbourg University, 67000 Strasbourg, France
| | - Gilles Kauffenstein
- INSERM, CNRS, MITOVASC, Equipe CarME, SFR ICAT, University Angers, 49000 Angers, France
- UMR INSERM 1260, CRBS, Strasbourg University, 67084 Strasbourg, France
| | - César Mattei
- INSERM, CNRS, MITOVASC, Equipe CarME, SFR ICAT, University Angers, 49000 Angers, France
| | | | - Daniel Henrion
- INSERM, CNRS, MITOVASC, Equipe CarME, SFR ICAT, University Angers, 49000 Angers, France
| | - Claire Legendre
- INSERM, CNRS, MITOVASC, Equipe CarME, SFR ICAT, University Angers, 49000 Angers, France
| | - Christian Legros
- INSERM, CNRS, MITOVASC, Equipe CarME, SFR ICAT, University Angers, 49000 Angers, France
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4
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Liu TT, Hou H, Du JL. A protocol for simultaneous Ca 2+ and morphology imaging of brain endothelial tip cells in larval zebrafish. STAR Protoc 2021; 2:100388. [PMID: 33778782 PMCID: PMC7982748 DOI: 10.1016/j.xpro.2021.100388] [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: 11/17/2022] Open
Abstract
Endothelial tip cells (ETCs) located at growing blood vessels display high morphological dynamics and associated intracellular Ca2+ activities with different spatiotemporal patterns during migration. Examining the Ca2+ activity and morphological dynamics of ETCs will provide an insight for understanding the mechanism of vascular development in organs, including the brain. Here, we describe a method for simultaneous monitoring and relevant analysis of the Ca2+ activity and morphology of growing brain ETCs in larval zebrafish. For complete details on the use and execution of this protocol, please refer to Liu et al. (2020). Image Ca2+ activity of brain endothelial tip cells (ETCs) in larval zebrafish Image the morphology of ETCs Quantify the spatiotemporal pattern of Ca2+ activities in ETCs Analyze the morphology of ETCs to trace the growing state
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Affiliation(s)
- Ting-Ting Liu
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Center for Excellence in Brain Science and Intelligence Technology, Shanghai Research Center for Brain Science and Brain-Inspired Intelligence, Chinese Academy of Sciences, 320 Yue-Yang Road, Shanghai 200031, China.,University of Chinese Academy of Sciences, 19A Yu-Quan Road, Beijing 100049, China
| | - Han Hou
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Center for Excellence in Brain Science and Intelligence Technology, Shanghai Research Center for Brain Science and Brain-Inspired Intelligence, Chinese Academy of Sciences, 320 Yue-Yang Road, Shanghai 200031, China
| | - Jiu-Lin Du
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Center for Excellence in Brain Science and Intelligence Technology, Shanghai Research Center for Brain Science and Brain-Inspired Intelligence, Chinese Academy of Sciences, 320 Yue-Yang Road, Shanghai 200031, China.,University of Chinese Academy of Sciences, 19A Yu-Quan Road, Beijing 100049, China.,School of Life Science and Technology, ShanghaiTech University, 319 Yue-Yang Road, Shanghai 200031, China
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5
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Lillo MA, Gaete PS, Puebla M, Burboa PC, Poblete I, Figueroa XF. Novel Pannexin-1-Coupled Signaling Cascade Involved in the Control of Endothelial Cell Function and NO-Dependent Relaxation. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2021; 2021:2678134. [PMID: 33688389 PMCID: PMC7914086 DOI: 10.1155/2021/2678134] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 01/03/2021] [Accepted: 01/13/2021] [Indexed: 12/11/2022]
Abstract
Deletion of pannexin-1 (Panx-1) leads not only to a reduction in endothelium-derived hyperpolarization but also to an increase in NO-mediated vasodilation. Therefore, we evaluated the participation of Panx-1-formed channels in the control of membrane potential and [Ca2+]i of endothelial cells. Changes in NO-mediated vasodilation, membrane potential, superoxide anion (O2 ·-) formation, and endothelial cell [Ca2+]i were analyzed in rat isolated mesenteric arterial beds and primary cultures of mesenteric endothelial cells. Inhibition of Panx-1 channels with probenecid (1 mM) or the Panx-1 blocking peptide 10Panx (60 μM) evoked an increase in the ACh (100 nM)-induced vasodilation of KCl-contracted mesenteries and in the phosphorylation level of endothelial NO synthase (eNOS) at serine 1177 (P-eNOSS1177) and Akt at serine 473 (P-AktS473). In addition, probenecid or 10Panx application activated a rapid, tetrodotoxin (TTX, 300 nM)-sensitive, membrane potential depolarization and [Ca2+]i increase in endothelial cells. Interestingly, the endothelial cell depolarization was converted into a transient spike after removing Ca2+ ions from the buffer solution and in the presence of 100 μM mibefradil or 10 μM Ni2+. As expected, Ni2+ also abolished the increment in [Ca2+]i. Expression of Nav1.2, Nav1.6, and Cav3.2 isoforms of voltage-dependent Na+ and Ca2+ channels was confirmed by immunocytochemistry. Furthermore, the Panx-1 channel blockade was associated with an increase in O2 ·- production. Treatment with 10 μM TEMPOL or 100 μM apocynin prevented the increase in O2 ·- formation, ACh-induced vasodilation, P-eNOSS1177, and P-AktS473 observed in response to Panx-1 inhibition. These findings indicate that the Panx-1 channel blockade triggers a novel complex signaling pathway initiated by the sequential activation of TTX-sensitive Nav channels and Cav3.2 channels, leading to an increase in NO-mediated vasodilation through a NADPH oxidase-dependent P-eNOSS1177, which suggests that Panx-1 may be involved in the endothelium-dependent control of arterial blood pressure.
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Affiliation(s)
- Mauricio A. Lillo
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago 8330025, Chile
| | - Pablo S. Gaete
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago 8330025, Chile
| | - Mariela Puebla
- Centro de Fisiología Celular e Integrativa, Facultad de Medicina-Clínica Alemana, Universidad del Desarrollo, Santiago, Chile
| | - Pía C. Burboa
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago 8330025, Chile
| | - Inés Poblete
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago 8330025, Chile
| | - Xavier F. Figueroa
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago 8330025, Chile
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Siegel G, Malmsten M, Ermilov E. Anionic biopolyelectrolytes of the syndecan/perlecan superfamily: physicochemical properties and medical significance. Adv Colloid Interface Sci 2014; 205:275-318. [PMID: 24534475 DOI: 10.1016/j.cis.2014.01.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Revised: 01/18/2014] [Accepted: 01/19/2014] [Indexed: 11/19/2022]
Abstract
In the review article presented here, we demonstrate that the connective tissue is more than just a matrix for cells and a passive scaffold to provide physical support. The extracellular matrix can be subdivided into proteins (collagen, elastin), glycoconjugates (structural glycoproteins, proteoglycans) and glycosaminoglycans (hyaluronan). Our main focus rests on the anionic biopolyelectrolytes of the perlecan/syndecan superfamily which belongs to extracellular matrix and cell membrane integral proteoglycans. Though the extracellular domain of the syndecans may well be performing a structural role within the extracellular matrix, a key function of this class of membrane intercalated proteoglycans may be to act as signal transducers across the plasma membrane and thus be more appropriately included in the group of cell surface receptors. Nevertheless, there is a continuum in functions of syndecans and perlecans, especially with respect to their structural role and biomedical significance. HS/CS proteoglycans are receptor sites for lipoprotein binding thus intervening directly in lipid metabolism. We could show that among all lipoproteins, HDL has the highest affinity to these proteoglycans and thus instals a feedforward forechecking loop against atherogenic apoB100 lipoprotein deposition on surface membranes and in subendothelial spaces. Therefore, HDL is not only responsible for VLDL/IDL/LDL cholesterol exit but also controls thoroughly the entry. This way, it inhibits arteriosclerotic nanoplaque formation. The ternary complex 'lipoprotein receptor (HS/CS-PG) - lipoprotein (LDL, oxLDL, Lp(a)) - calcium' may be interpreted as arteriosclerotic nanoplaque build-up on the molecular level before any cellular reactivity, possibly representing the arteriosclerotic primary lesion combined with endothelial dysfunction. With laser-based ellipsometry we could demonstrate that nanoplaque formation is a Ca(2+)-driven process. In an in vitro biosensor application of HS-PG coated silica surfaces we tested nanoplaque formation and size in clinical trials with cardiovascular high-risk patients who underwent treatment with ginkgo or fluvastatin. While ginkgo reduced nanoplaque formation (size) by 14.3% (23.4%) in the isolated apoB100 lipid fraction at a normal blood Ca(2+) concentration, the effect of the statin with a reduction of 44.1% (25.4%) was more pronounced. In addition, ginkgo showed beneficial effects on several biomarkers of oxidative stress and inflammation. Besides acting as peripheral lipoprotein binding receptor, HS/CS-PG is crucially implicated in blood flow sensing. A sensor molecule has to fulfil certain mechanochemical and mechanoelectrical requirements. It should possess viscoelastic and cation binding properties capable of undergoing conformational changes caused both mechanically and electrostatically. Moreover, the latter should be ion-specific. Under no-flow conditions, the viscoelastic polyelectrolyte at the endothelium - blood interface assumes a random coil form. Blood flow causes a conformational change from the random coil state to the directed filament structure state. This conformational transition effects a protein unfurling and molecular elongation of the GAG side chains like in a 'stretched' spring. This configuration is therefore combined with an increase in binding sites for Na(+) ions. Counterion migration of Na(+) along the polysaccharide chain is followed by transmembrane Na(+) influx into the endothelial cell and by endothelial cell membrane depolarization. The simultaneous Ca(2+) influx releases NO and PGI2, vasodilatation is the consequence. Decrease in flow reverses the process. Binding of Ca(2+) and/or apoB100 lipoproteins (nanoplaque formation) impairs the flow sensor function. The physicochemical and functional properties of proteoglycans are due to their amphiphilicity and anionic polyelectrolyte character. Thus, they potently interact with cations, albeit in a rather complex manner. Utilizing (23)Na(+) and (39)K(+) NMR techniques, we could show that, both in HS-PG solutions and in native vascular connective tissue, the mode of interaction for monovalent cations is competition. Mg(2+) and Ca(2+) ions, however, induced a conformational change leading to an increased allosteric, cooperative K(+) and Na(+) binding, respectively. Since extracellular matrices and basement membranes form a tight-fitting sheath around the cell membrane of muscle and Schwann cells, in particular around sinus node cells of the heart, and underlie all epithelial and endothelial cell sheets and tubes, a release of cations from or an adsorption to these polyanionic macromolecules can transiently lead to fast and drastic activity changes in these tiny extracellular tissue compartments. The ionic currents underlying pacemaker and action potential of sinus node cells are fundamentally modulated. Therefore, these polyelectrolytic ion binding characteristics directly contribute to and intervene into heart rhythm.
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Affiliation(s)
- G Siegel
- Charité - University Clinic Berlin, 10117 Berlin, Germany; University of Uppsala Biomedical Center, 751 23 Uppsala, Sweden.
| | - M Malmsten
- University of Uppsala Biomedical Center, 751 23 Uppsala, Sweden; Charité - University Clinic Berlin, 10117 Berlin, Germany
| | - E Ermilov
- Charité - University Clinic Berlin, 10117 Berlin, Germany
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7
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Black J, Waxman S. Noncanonical Roles of Voltage-Gated Sodium Channels. Neuron 2013; 80:280-91. [DOI: 10.1016/j.neuron.2013.09.012] [Citation(s) in RCA: 111] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/11/2013] [Indexed: 12/19/2022]
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Bradley E, Webb TI, Hollywood MA, Sergeant GP, McHale NG, Thornbury KD. The cardiac sodium current Na(v)1.5 is functionally expressed in rabbit bronchial smooth muscle cells. Am J Physiol Cell Physiol 2013; 305:C427-35. [PMID: 23784541 DOI: 10.1152/ajpcell.00034.2013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
A collagenase-proteinase mixture was used to isolate airway smooth muscle cells (ASMC) from rabbit bronchi, and membrane currents were recorded using the whole cell patch-clamp technique. Stepping from -100 mV to a test potential of -40 mV evoked a fast voltage-dependent Na(+) current, sometimes with an amplitude of several nanoamperes. The current disappeared within 15 min of exposure to papain + DTT (n = 6). Comparison of the current in ASMC with current mediated by NaV1.5 α-subunits expressed in human embryonic kidney cells revealed similar voltage dependences of activation (V1/2 = -42 mV for NaV1.5) and sensitivities to TTX (IC50 = 1.1 and 1.2 μM for ASMC and NaV1.5, respectively). The current in ASMC was also blocked by lidocaine (IC50 = 160 μM). Although veratridine, an agonist of voltage-gated Na(+) channels, reduced the peak current by 33%, it slowed inactivation, resulting in a fourfold increase in sustained current (measured at 25 ms after onset). In current-clamp mode, veratridine prolonged evoked action potentials from 37 ± 9 to 1,053 ± 410 ms (n = 8). Primers for NaV1.2-1.9 were used to amplify mRNA from groups of ∼20 isolated ASMC and from whole bronchial tissue by RT-PCR. Transcripts for NaV1.2, NaV1.3, and NaV1.5-1.9 were detected in whole tissue, but only NaV1.2 and NaV1.5 were detected in single cells. We conclude that freshly dispersed rabbit ASMC express a fast voltage-gated Na(+) current that is mediated mainly by the NaV1.5 subtype.
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Affiliation(s)
- E Bradley
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
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Black JA, Waxman SG. Sodium channels and microglial function. Exp Neurol 2011; 234:302-15. [PMID: 21985863 DOI: 10.1016/j.expneurol.2011.09.030] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Revised: 09/09/2011] [Accepted: 09/26/2011] [Indexed: 12/19/2022]
Abstract
Microglia are resident immune cells that provide continuous surveillance within the central nervous system (CNS) and respond to perturbations of brain and spinal cord parenchyma with an array of effector functions, including proliferation, migration, phagocytosis, secretions of multiple cytokines/chemokines and promotion of repair. To sense alterations within their environment, microglia express a large number of cell surface receptors, ion channels and adhesion molecules, which activate complex and dynamic signaling pathways. In the present chapter, we review studies that demonstrate that microglia in vivo and in vitro express specific voltage-gated sodium channel isoforms, and that blockade of sodium channel activity can attenuate several effector functions of microglia. These studies also provide strong evidence that Nav1.6 is the predominant sodium channel isoform expressed in microglia and that its activity contributes to the response of microglia to multiple activating signals.
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Affiliation(s)
- Joel A Black
- Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06511, USA.
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10
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Andrikopoulos P, Fraser SP, Patterson L, Ahmad Z, Burcu H, Ottaviani D, Diss JKJ, Box C, Eccles SA, Djamgoz MBA. Angiogenic functions of voltage-gated Na+ Channels in human endothelial cells: modulation of vascular endothelial growth factor (VEGF) signaling. J Biol Chem 2011; 286:16846-60. [PMID: 21385874 DOI: 10.1074/jbc.m110.187559] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Voltage-gated sodium channel (VGSC) activity has previously been reported in endothelial cells (ECs). However, the exact isoforms of VGSCs present, their mode(s) of action, and potential role(s) in angiogenesis have not been investigated. The main aims of this study were to determine the role of VGSC activity in angiogenic functions and to elucidate the potentially associated signaling mechanisms using human umbilical vein endothelial cells (HUVECs) as a model system. Real-time PCR showed that the primary functional VGSC α- and β-subunit isoforms in HUVECs were Nav1.5, Nav1.7, VGSCβ1, and VGSCβ3. Western blots verified that VGSCα proteins were expressed in HUVECs, and immunohistochemistry revealed VGSCα expression in mouse aortic ECs in vivo. Electrophysiological recordings showed that the channels were functional and suppressed by tetrodotoxin (TTX). VGSC activity modulated the following angiogenic properties of HUVECs: VEGF-induced proliferation or chemotaxis, tubular differentiation, and substrate adhesion. Interestingly, different aspects of angiogenesis were controlled by the different VGSC isoforms based on TTX sensitivity and effects of siRNA-mediated gene silencing. Additionally, we show for the first time that TTX-resistant (TTX-R) VGSCs (Nav1.5) potentiate VEGF-induced ERK1/2 activation through the PKCα-B-RAF signaling axis. We postulate that this potentiation occurs through modulation of VEGF-induced HUVEC depolarization and [Ca(2+)](i). We conclude that VGSCs regulate multiple angiogenic functions and VEGF signaling in HUVECs. Our results imply that targeting VGSC expression/activity could be a novel strategy for controlling angiogenesis.
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Affiliation(s)
- Petros Andrikopoulos
- Division of Cell and Molecular Biology, Neuroscience Solutions to Cancer Research Group, Sir Alexander Fleming Building, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom.
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11
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Black JA, Liu S, Waxman SG. Sodium channel activity modulates multiple functions in microglia. Glia 2009; 57:1072-81. [PMID: 19115387 DOI: 10.1002/glia.20830] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Microglia provide surveillance in the central nervous system and become activated following tissue insult. Detailed mechanisms by which microglia detect and respond to their environment are not fully understood, but it is known that microglia express a number of surface receptors and ion channels, including voltage-gated sodium channels, that participate in transduction of external stimuli to intra-cellular responses. To determine whether activated microglia are affected by the activity of sodium channels, we examined the expression of sodium channel isoforms in cultured microglia and the action of sodium channel blockade on multiple functions of activated microglia. Rat microglia in vitro express tetrodotoxin (TTX)-sensitive sodium channels Nav1.1 and Nav1.6 and the TTX-resistant channel Nav1.5, but not detectable levels of Nav1.2, Nav1.3, Nav1.7, Nav1.8, and Nav1.9. Sodium channel blockade with phenytoin (40 microM) and TTX (0.3 microM) significantly reduced by 50-60% the phagocytic activity of microglia activated with lipopolysaccharide (LPS); blockade with 10 microM TTX did not further reduce phagocytic activity. Phenytoin attenuated by approximately 50% the release of IL-1 alpha, IL-1 beta, and TNF-alpha from LPS-stimulated microglia, but had minimal effects on the release of IL-2, IL-4, IL-6, IL-10, MCP-1, and TGF-alpha. TTX (0.3 microM) reduced, but to a smaller extent, the release of IL-1 alpha, IL-1 beta, and TNF-alpha from activated microglia. Phenytoin and TTX also significantly decreased by approximately 50% adenosine triphosphate-induced migration by microglia; studies with microglia cultured from med mice (which lack Nav1.6) indicate that Nav1.6 plays a role in microglial migration. The results demonstrate that the activity of sodium channels contributes to effector roles of activated microglia.
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Affiliation(s)
- Joel A Black
- Department of Neurology and Center for Neuroscience and Regeneration Research, Yale School of Medicine, New Haven, Connecticut 06518, USA.
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12
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Selective reciprocity in antimicrobial activity versus cytotoxicity of hBD-2 and crotamine. Proc Natl Acad Sci U S A 2009; 106:14972-7. [PMID: 19706485 DOI: 10.1073/pnas.0904465106] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Recent discoveries suggest cysteine-stabilized toxins and antimicrobial peptides have structure-activity parallels derived by common ancestry. Here, human antimicrobial peptide hBD-2 and rattlesnake venom-toxin crotamine were compared in phylogeny, 3D structure, target cell specificity, and mechanisms of action. Results indicate a striking degree of structural and phylogenetic congruence. Importantly, these polypeptides also exhibited functional reciprocity: (i) they exerted highly similar antimicrobial pH optima and spectra; (ii) both altered membrane potential consistent with ion channel-perturbing activities; and (iii) both peptides induced phosphatidylserine accessibility in eukaryotic cells. However, the Na(v) channel-inhibitor tetrodotoxin antagonized hBD-2 mechanisms, but not those of crotamine. As crotamine targets eukaryotic ion channels, computational docking was used to compare hBD-2 versus crotamine interactions with prototypic bacterial, fungal, or mammalian Kv channels. Models support direct interactions of each peptide with Kv channels. However, while crotamine localized to occlude Kv channels in eukaryotic but not prokaryotic cells, hBD-2 interacted with prokaryotic and eukaryotic Kv channels but did not occlude either. Together, these results support the hypothesis that antimicrobial and cytotoxic polypeptides have ancestral structure-function homology, but evolved to preferentially target respective microbial versus mammalian ion channels via residue-specific interactions. These insights may accelerate development of anti-infective or therapeutic peptides that selectively target microbial or abnormal host cells.
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Black JA, Waxman SG. Phenytoin protects central axons in experimental autoimmune encephalomyelitis. J Neurol Sci 2008; 274:57-63. [PMID: 18485368 DOI: 10.1016/j.jns.2008.04.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2008] [Revised: 03/20/2008] [Accepted: 04/02/2008] [Indexed: 10/22/2022]
Abstract
Axon degeneration is a major contributor to non-remitting deficits in multiple sclerosis (MS). Thus the development of therapies to provide protection of axons has elicited considerable interest. Voltage-gated sodium channels have been implicated in the injury cascade leading to axonal damage, and sodium-channel blockers have shown efficacy in ameliorating axonal damage in disease models following anoxia, trauma and damaging levels of nitric oxide (NO). Here we discuss studies in our laboratory that examined the protective effects of phenytoin, a well-characterized sodium-channel blocker, in the inflammatory/demyelinating disorder experimental autoimmune encephalomyelitis (EAE), a model of MS. Administration of phenytoin to C57/Bl6 mice inoculated with rat myelin oligodendrocyte glycoprotein (MOG) provides improved clinical status, preservation of axons, enhanced action potential conduction and reduced immune infiltrates compared to untreated mice with EAE. Moreover, continuous treatment with phenytoin provides these protective actions for at least 180 days post-MOG injection. The withdrawal of phenytoin from mice inoculated with MOG, however, is accompanied by acute exacerbation of EAE, with significant mortality and infiltration of immune cells in the CNS. Our studies demonstrate the efficacy of phenytoin as a neuroprotectant in EAE. Our results also, however, indicate that we need to learn more about the long-term effects of sodium-channel blockers, and of their withdrawal, in neuroinflammatory disorders.
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Affiliation(s)
- Joel A Black
- Department of Neurology and Center for Neuroscience and Regeneration Research, Yale School of Medicine, New Haven, CT 06510, United States.
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14
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Black JA, Liu S, Carrithers M, Carrithers LM, Waxman SG. Exacerbation of experimental autoimmune encephalomyelitis after withdrawal of phenytoin and carbamazepine. Ann Neurol 2007; 62:21-33. [PMID: 17654737 DOI: 10.1002/ana.21172] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
OBJECTIVE In vitro observations and studies in murine experimental autoimmune encephalomyelitis (EAE) have shown protective effects of sodium channel blockers on central nervous system axons and improved clinical status when treatment is continued throughout the period of observation. Several clinical studies of sodium channel blockers are under way in patients with multiple sclerosis. Here we asked whether a protective effect would persist after withdrawal of a sodium channel blocker. METHODS We studied a mouse model of myelin oligodendrocyte glycoprotein-induced EAE treated with phenytoin or carbamazepine. RESULTS Both phenytoin and carbamazepine significantly improved the clinical course of the disease. Withdrawal of phenytoin resulted in acute exacerbation, accompanied by a significantly increased inflammatory infiltrate within the central nervous system and the death of nearly 60% of EAE mice. There were no clinical worsening or deaths in control mice after withdrawal of phenytoin. Withdrawal of carbamazepine led to acute worsening of EAE symptoms, increased inflammatory infiltrate, and was associated with the death of 8% of mice. INTERPRETATION These results, together with results showing effects of sodium channel blockers in immune cells, raise questions about the long-term effects of sodium channel blockers in neuroinflammatory disorders, and suggest that clinical studies of sodium channel blockers in these disorders should be planned carefully.
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Affiliation(s)
- Joel A Black
- Department of Neurology and Center for Neuroscience and Regeneration Research, Yale School of Medicine, New Haven, CT 06520, USA
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15
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Figueroa XF, Chen CC, Campbell KP, Damon DN, Day KH, Ramos S, Duling BR. Are voltage-dependent ion channels involved in the endothelial cell control of vasomotor tone? Am J Physiol Heart Circ Physiol 2007; 293:H1371-83. [PMID: 17513486 DOI: 10.1152/ajpheart.01368.2006] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In the microcirculation, longitudinal conduction of vasomotor responses provides an essential means of coordinating flow distribution among vessels in a complex network. Spread of current along the vessel axis can display a regenerative component, which leads to propagation of vasomotor signals over many millimeters; the ionic basis for the regenerative response is unknown. We examined the responses to 10 s of focal electrical stimulation (30 Hz, 2 ms, 30 V) of mouse cremaster arterioles to test the hypothesis that voltage-dependent Na(+) (Na(v)) and Ca(2+) channels might be activated in long-distance signaling in microvessels. Electrical stimulation evoked a vasoconstriction at the site of stimulation and a spreading, nondecremental conducted dilation. Endothelial damage (air bubble) blocked conduction of the vasodilation, indicating an involvement of the endothelium. The Na(v) channel blocker bupivacaine also blocked conduction, and TTX attenuated it. The Na(v) channel activator veratridine induced an endothelium-dependent dilation. The Na(v) channel isoforms Na(v)1.2, Na(v)1.6, and Na(v)1.9 were detected in the endothelial cells of cremaster arterioles by immunocytochemistry. These findings are consistent with the involvement of Na(v) channels in the conducted response. BAPTA buffering of endothelial cell Ca(2+) delayed and reduced the conducted dilation, which was almost eliminated by Ni(2+), amiloride, or deletion of alpha(1H) T-type Ca(2+) (Ca(v)3.2) channels. Blockade of endothelial nitric oxide synthase or Ca(2+)-activated K(+) channels also inhibited the conducted vasodilation. Our findings indicate that an electrically induced signal can propagate along the vessel axis via the endothelium and can induce sequential activation of Na(v) and Ca(v)3.2 channels. The resultant Ca(2+) influx activates endothelial nitric oxide synthase and Ca(2+)-activated K(+) channels, triggering vasodilation.
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Affiliation(s)
- Xavier F Figueroa
- Departamento de Ciencias Fisiológicas, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
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16
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Brackenbury WJ, Djamgoz MBA. Nerve growth factor enhances voltage-gated Na+ channel activity and Transwell migration in Mat-LyLu rat prostate cancer cell line. J Cell Physiol 2007; 210:602-8. [PMID: 17149708 PMCID: PMC4123444 DOI: 10.1002/jcp.20846] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The highly dynamic nature of voltage-gated Na+ channel (VGSC) expression and its controlling mechanism(s) are not well understood. In this study, we investigated the possible involvement of nerve growth factor (NGF) in regulating VGSC activity in the strongly metastatic Mat-LyLu cell model of rat prostate cancer (PCa). NGF increased peak VGSC current density in a time- and dose-dependent manner. NGF also shifted voltage to peak and the half-activation voltage to more positive potentials, and produced currents with faster kinetics of activation; sensitivity to the VGSC blocker tetrodotoxin (TTX) was not affected. The NGF-induced increase in peak VGSC current density was suppressed by both the pan-trk antagonist K252a, and the protein kinase A (PKA) inhibitor KT5720. NGF did not affect the Nav1.7 mRNA level, but the total VGSC alpha-subunit protein level was upregulated. NGF potentiated the cells' migration in Transwell assays, and this was not affected by TTX. We concluded that NGF upregulated functional VGSC expression in Mat-LyLu cells, with PKA as a signaling intermediate, but enhancement of migration by NGF was independent of VGSC activity.
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Affiliation(s)
| | - Mustafa B. A. Djamgoz
- Correspondence to: Professor M. B. A. Djamgoz, Neuroscience Solutions to Cancer Research Group, Division of Cell and Molecular Biology, Sir Alexander Fleming Building, Imperial College London, South Kensington Campus, London SW7 2AZ, UK, Tel: (0) 207 594 5370, Fax: (0) 207 584 2056,
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17
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Lee-Kwon W, Goo JH, Zhang Z, Silldorff EP, Pallone TL. Vasa recta voltage-gated Na+ channel Nav1.3 is regulated by calmodulin. Am J Physiol Renal Physiol 2006; 292:F404-14. [PMID: 16912065 DOI: 10.1152/ajprenal.00070.2006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Rat descending vasa recta (DVR) express a tetrodotoxin (TTX)-sensitive voltage-operated Na(+) (Na(V)) conductance. We examined expression of Na(V) isoforms in DVR and tested for regulation of Na(V) currents by calmodulin (CaM). RT-PCR in isolated permeabilized DVR using degenerate primers targeted to TTX-sensitive isoforms amplified a product whose sequence identified only Na(V)1.3. Immunoblot of outer medullary homogenate verified Na(V)1.3 expression, and fluorescent immunochemistry showed Na(V)1.3 expression in isolated vessels. Immunochemistry in outer medullary serial sections confirmed that Na(V)1.3 is confined to alpha-smooth muscle actin-positive vascular bundles. Na(V)1.3 possesses a COOH-terminal CaM binding motifs. Using pull-down assays and immunoprecipitation experiments, we verified that CaM binds to either full-length Na(V)1.3 or a GST-Na(V)1.3 COOH-terminal fusion protein. In patch-clamp experiments, Na(V) currents were suppressed by calmodulin inhibitory peptide (CIP; 100 nM) or the CaM inhibitor N-(6-aminohexyl)-5-chloro-1-naphthalene-sulphonamide hydrochloride (W7). Neither CIP nor W7 altered the voltage dependence of pericyte Na(V) currents; however, raising electrode free Ca(2+) from 20 to approximately 2,000 nM produced a depolarizing shift of activation. In vitro binding of CaM to GST-Na(V)1.3C was not affected by Ca(2+) concentration. We conclude that Na(V)1.3 is expressed by DVR, binds to CaM, and is regulated by CaM and Ca(2+). Inhibition of CaM binding suppresses pericyte Na(V) currents.
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Affiliation(s)
- Whaseon Lee-Kwon
- Division of Nephrology, Department of Medicine, University of Maryland School of Medicine, Baltimore 21201, USA
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18
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Abstract
This review highlights the current lack of therapeutic and prophylactic treatments for use against inhaled biological toxins, especially those considered as potential biological warfare (BW) or terrorist threats. Although vaccine development remains a priority, the use of rapidly deployable adjunctive therapeutic or prophylactic drugs could be life-saving in severe cases of intoxication or where vaccination has not been possible or immunity not established. The current lack of such drugs is due to many factors. Thus, methods involving molecular modelling are limited by the extent to which the cellular receptor sites and mode of action and structure of a toxin need to be known. There is also our general lack of knowledge of what effect individual toxins will have when inhaled into the lungs - whether and to what extent the action will be cell specific and cytotoxic or rather an acute inflammatory response requiring the use of immunomodulators. Possible sources of specific high-affinity toxin antagonists being investigated include monoclonal antibodies, selected oligonucleotides (aptamers) and derivatized dendritic polymers (dendrimers). The initial selection of suitable agents of these kinds can be made using cytotoxicity assays involving cultured normal human lung cells and a range of suitable indicators. The possibility that a mixture of selected antibody, aptamer or dendrimer-based materials for one or more toxins could be delivered simultaneously as injections or as inhaled aerosol sprays should be investigated.
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Affiliation(s)
- Brian M Paddle
- DSTO, Platforms Sciences Laboratory, 506 Lorimer Street, Fishermans Bend, Victoria 3207, Australia.
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19
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Abstract
Endothelial cells (EC) form a unique signal-transducing surface in the vascular system. The abundance of ion channels in the plasma membrane of these nonexcitable cells has raised questions about their functional role. This review presents evidence for the involvement of ion channels in endothelial cell functions controlled by intracellular Ca(2+) signals, such as the production and release of many vasoactive factors, e.g., nitric oxide and PGI(2). In addition, ion channels may be involved in the regulation of the traffic of macromolecules by endocytosis, transcytosis, the biosynthetic-secretory pathway, and exocytosis, e.g., tissue factor pathway inhibitor, von Willebrand factor, and tissue plasminogen activator. Ion channels are also involved in controlling intercellular permeability, EC proliferation, and angiogenesis. These functions are supported or triggered via ion channels, which either provide Ca(2+)-entry pathways or stabilize the driving force for Ca(2+) influx through these pathways. These Ca(2+)-entry pathways comprise agonist-activated nonselective Ca(2+)-permeable cation channels, cyclic nucleotide-activated nonselective cation channels, and store-operated Ca(2+) channels or capacitative Ca(2+) entry. At least some of these channels appear to be expressed by genes of the trp family. The driving force for Ca(2+) entry is mainly controlled by large-conductance Ca(2+)-dependent BK(Ca) channels (slo), inwardly rectifying K(+) channels (Kir2.1), and at least two types of Cl( -) channels, i.e., the Ca(2+)-activated Cl(-) channel and the housekeeping, volume-regulated anion channel (VRAC). In addition to their essential function in Ca(2+) signaling, VRAC channels are multifunctional, operate as a transport pathway for amino acids and organic osmolytes, and are possibly involved in endothelial cell proliferation and angiogenesis. Finally, we have also highlighted the role of ion channels as mechanosensors in EC. Plasmalemmal ion channels may signal rapid changes in hemodynamic forces, such as shear stress and biaxial tensile stress, but also changes in cell shape and cell volume to the cytoskeleton and the intracellular machinery for metabolite traffic and gene expression.
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Affiliation(s)
- B Nilius
- Department of Physiology, KU Leuven, Campus Gasthuisberg, Leuven, Belgium.
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20
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Donahue LM, Coates PW, Lee VH, Ippensen DC, Arze SE, Poduslo SE. The cardiac sodium channel mRNA is expressed in the developing and adult rat and human brain. Brain Res 2000; 887:335-43. [PMID: 11134623 DOI: 10.1016/s0006-8993(00)03033-x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Expression of the rat (RH-I/SkM2) and human (hH1/SCN5A) tetrodotoxin-resistant (TTX-R), voltage-sensitive sodium channels is thought to be specific to cardiac tissue. We detected RH-I/SkM2 mRNA in newborn rat brain using both RNase protection assay analysis and in situ hybridization and in adult rat brain using RNase protection assay analysis. This expression was observed primarily in developing limbic structures of the cerebrum and diencephalon, and in the medulla of the brain stem. Using RT-PCR analysis, we detected hH1/SCN5A mRNA in both fetal and adult human brain. Interestingly, mutations in the human cardiac sodium channel are known to lead to cardiac abnormalities, which result in arrhythmias and frequently in sudden cardiac death. If these mutant channels were also expressed in limbic regions of the brain, alterations in channel function could have drastic effects on the brain's signaling ability, possibly promoting seizure activity.
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Affiliation(s)
- L M Donahue
- Cascade Biologics, Inc., 4475 SW Scholls Ferry Road, Portland, OR 97225, USA.
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21
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Traub O, Ishida T, Ishida M, Tupper JC, Berk BC. Shear stress-mediated extracellular signal-regulated kinase activation is regulated by sodium in endothelial cells. Potential role for a voltage-dependent sodium channel. J Biol Chem 1999; 274:20144-50. [PMID: 10400628 DOI: 10.1074/jbc.274.29.20144] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Fluid shear stress is an important regulator of endothelial cell (EC) function. To determine whether mechanosensitive ion channels participate in the EC response to shear stress, we characterized the role of ion transport in shear stress-mediated extracellular signal-regulated kinase (ERK1/2) stimulation. Replacement of all extracellular Na+ with either N-methyl-D-glucamine or choline chloride increased the ERK1/2 stimulation in response to shear stress by 1.89 +/- 0.1-fold. The Na+ effect was concentration-dependent (maximal effect, </=12.5 mM) and was specific for shear stress-mediated ERK1/2 activation as epidermal growth factor-stimulated ERK1/2 activation was unaffected by removal of extracellular Na+. Shear stress-mediated ERK1/2 activation was potentiated by the voltage-gated sodium channel antagonist, tetrodotoxin (100 nM), to a magnitude similar to that achieved with extracellular Na+ withdrawal. Transfection of Chinese hamster ovary cells with a rat brain type IIa voltage-gated sodium channel completely inhibited shear stress-mediated ERK1/2 activation in these cells. Inhibition was reversed by performing the experiment in sodium-free buffer or by including tetrodotoxin in the buffer. Western blotting of bovine and human EC lysates with SP19 antibody detected a 250-kDa protein consistent with the voltage-gated sodium channel. Degenerate polymerase chain reaction of cDNA from primary human EC yielded transcripts whose sequences were identical to the sodium channel SCN4a and SCN8a alpha subunit genes. These results indicate that shear stress-mediated ERK1/2 activation is regulated by extracellular sodium and demonstrate that ion transport via Na+ channels modulates EC responses to shear stress.
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Affiliation(s)
- O Traub
- Department of Pathology, University of Washington, Seattle, Washington 98195, USA
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22
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Gosling M, Harley SL, Turner RJ, Carey N, Powell JT. Human saphenous vein endothelial cells express a tetrodotoxin-resistant, voltage-gated sodium current. J Biol Chem 1998; 273:21084-90. [PMID: 9694861 DOI: 10.1074/jbc.273.33.21084] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Whole-cell patch-clamp electrophysiological investigation of endothelial cells cultured from human saphenous vein (HSVECs) has identified a voltage-gated Na+ current with a mean peak magnitude of -595 +/- 49 pA (n = 75). This current was inhibited by tetrodotoxin (TTX) in a concentration-dependent manner, with an IC50 value of 4.7 microM, suggesting that it was of the TTX-resistant subtype. An antibody directed against the highly conserved intracellular linker region between domains III and IV of known Na+ channel alpha-subunits was able to retard current inactivation when applied intracellularly. This antibody identified a 245-kDa protein from membrane lysates on Western blotting and positively immunolabeled both cultured HSVECs and intact venous endothelium. HSVECs were also shown by reverse transcription-polymerase chain reaction to contain transcripts of the hH1 sodium channel gene. The expression of Na+ channels by HSVECs was shown using electrophysiology and cell-based enzyme-linked immunosorbent assay to be dependent on the concentration and source of human serum. Together, these results suggest that TTX-resistant Na+ channels of the hH1 isoform are expressed in human saphenous vein endothelium and that the presence of these channels is controlled by a serum factor.
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Affiliation(s)
- M Gosling
- Department of Vascular Surgery, Imperial College School of Medicine at Charing Cross, Charing Cross Hospital, Fulham Palace Road, London W6 8RF, United Kingdom.
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23
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Diss JK, Stewart D, Fraser SP, Black JA, Dib-Hajj S, Waxman SG, Archer SN, Djamgoz MB. Expression of skeletal muscle-type voltage-gated Na+ channel in rat and human prostate cancer cell lines. FEBS Lett 1998; 427:5-10. [PMID: 9613589 DOI: 10.1016/s0014-5793(98)00378-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Previous electrophysiological work has demonstrated expression of a voltage-gated Na+ channel (VGSC) specifically in two highly metastatic prostatic epithelial tumour cell lines: MAT-LyLu (rat) and PC-3 (human). However, the identity of the channel(s) present was uncertain. The present study used a combination of molecular biological techniques to demonstrate that full-length skeletal muscle type 1 (SkM1) VGSC mRNA is present in the mRNA pool of the MAT-LyLu cell line. mRNA for this particular channel type was also expressed in the PC-3 cells. In situ hybridisation data suggested that the level and pattern of rSkM1 mRNA expression were different in the Dunning cells of markedly different metastatic potential. Interestingly, the same type of mRNA was also detected in the weakly metastatic counterparts of the cells: AT-2 (rat) and LNCaP (human).
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Affiliation(s)
- J K Diss
- Department of Biology, Imperial College of Science, Technology and Medicine, London, UK
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Walsh KB, Wolf MB, Fan J. Voltage-gated sodium channels in cardiac microvascular endothelial cells. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 274:H506-12. [PMID: 9486254 DOI: 10.1152/ajpheart.1998.274.2.h506] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The goal of this study was to determine whether inward Na+ or Ca2+ currents could be measured in cardiac microvascular endothelial cells (CMEC). CMEC were isolated from rat ventricular muscle and studied during days 1-4 in culture. Differential uptake of fluorescently labeled acetylated low-density lipoproteins (LDL) indicated that the primary culture contained > 90% CMEC. Membrane currents were measured with the use of the whole cell arrangement of the patch-clamp technique with a Cs+ internal solution to prevent contamination by outward K+ currents. Voltage steps positive to -30 mV resulted in the activation of a fast, inward Na+ current (INa). In 20 cells examined, the peak inward current measured at 0 mV was 2.1 pA/pF. The half-maximal voltage required for inactivation of INa was -45 mV, and the current recovered from inactivation with a time constant of 10 ms. Inward currents were eliminated by replacement of external sodium with N-methylglucamine and were blocked by both tetrodotoxin (TTX) (dissociation constant = 5 nM) and saxitoxin (50 nM). Stimulation of protein kinase C, through application of phorbol 12,13-dibutyrate, resulted in an increase in the amplitude of INa without any change in the voltage dependence of current activation. Thus the endothelium of cardiac microvessels may be unique in expressing voltage gated, TTX-sensitive Na+ channels.
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Affiliation(s)
- K B Walsh
- Department of Pharmacology, School of Medicine, University of South Carolina, Columbia 29208, USA
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25
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Abstract
The functional impact of ion channels in vascular endothelial cells (ECs) is still a matter of controversy. This review describes different types of ion channels in ECs and their role in electrogenesis, Ca2+ signaling, vessel permeability, cell-cell communication, mechano-sensor functions, and pH and volume regulation. One major function of ion channels in ECs is the control of Ca2+ influx either by a direct modulation of the Ca2+ influx pathway or by indirect modulation of K+ and Cl- channels, thereby clamping the membrane at a sufficiently negative potential to provide the necessary driving force for a sustained Ca2+ influx. We discuss various mechanisms of Ca2+ influx stimulation: those that activate nonselective, Ca(2+)-permeable cation channels or those that activate Ca(2+)-selective channels, exclusively or partially operated by the filling state of intracellular Ca2+ stores. We also describe the role of various Ca(2+)- and shear stress-activated K+ channels and different types of Cl- channels for the regulation of the membrane potential.
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Affiliation(s)
- B Nilius
- Laboratorium voor Fysiologie, KU Leuven, Belgium
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Gáspár R, Weidema AF, Krasznai Z, Nijweide PJ, Ypey DL. Tetrodotoxin-sensitive fast Na+ current in embryonic chicken osteoclasts. Pflugers Arch 1995; 430:596-8. [PMID: 7491289 DOI: 10.1007/bf00373899] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
A voltage-dependent, fast, transient inward current was characterized in embryonic chicken osteoclasts using the permeabilized patch configuration of the patch-clamp technique. The current was activated by depolarizations to higher than -28 +/- 4 mV from a holding potential of -80 mV. It peaked within 1-1.5 ms, and inactivated within 3.3-6.9 ms. The 50% inactivation voltage was -59 +/- 6 mV with a steepness factor of 0.11 +/- 0.06. The current disappeared with the removal of extracellular Na+ and was reversibly blocked by tetrodotoxin (K0.5 < 15 nM) but not by verapamil (< or = 100 microM). We conclude that this new current in embryonic chicken osteoclasts is a sodium current known from excitable cells.
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Affiliation(s)
- R Gáspár
- Biophysics Department, University Medical School, Debrecen, Hungary
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