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Yin JB, Liu HX, Dong QQ, Wu HH, Liang ZW, Fu JT, Zhao WJ, Hu HQ, Guo HW, Zhang T, Lu YC, Jin S, Wang XL, Cao BZ, Wang Z, Ding T. Correlative increasing expressions of KIF5b and Nav1.7 in DRG neurons of rats under neuropathic pain conditions. Physiol Behav 2023; 263:114115. [PMID: 36773735 DOI: 10.1016/j.physbeh.2023.114115] [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: 09/11/2022] [Revised: 01/30/2023] [Accepted: 02/08/2023] [Indexed: 02/11/2023]
Abstract
Nav1.7, one of tetrodotoxin-sensitive voltage-gated sodium channels, mainly expressed in the small diameter dorsal root ganglion (DRG) neurons. The expression and accumulation on neuronal membrane of Nav1.7 increased following peripheral tissue inflammation or nerve injury. However, the mechanisms for membrane accumulation of Nav1.7 remained unclear. We report that KIF5b, a highly expressed member of the kinesin-1 family in DRGs, promoted the translocation of Nav1.7 to the plasma membrane in DRG neurons of the rat. Following nociceptive behaviors in rats induced by peripheral spared nerve injury (SNI), synchronously increased KIF5b and Nav1.7 expressions were observed in DRGs. Immunohistochemistry staining demonstrated the co-expressions of KIF5b and Nav1.7 in the same DRG neurons. Immunoprecipitation experiments further confirmed the interactions between KIF5b and Nav1.7. Moreover, intrathecal injections of KIF5b shRNA moderated the SNI-induced both mechanical and thermal hyperalgesia. The rescued analgesic effects also alleviated SNI-induced anxiety-like behaviors. In sum, KIF5b was required for the membrane localizations of Nav1.7, which suggests a novel mechanism for the trafficking of Nav1.7 involved in neuropathic pain.
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Affiliation(s)
- Jun-Bin Yin
- Department of Neurology, the 960th Hospital of PLA, Jinan 250031, China; Institute of Orthopaedics, Xijing Hospital, The Fourth Military Medical University, Xi'an 710032, China; Department of Anatomy, Histology and Embryology, The Fourth Military Medical University, Xi'an 710032, China
| | - Hai-Xia Liu
- Department of Obstetrics and Gynecology, Shandong Provincial Hospital, Jinan 250021, China
| | - Qin-Qin Dong
- Department of Neurology, the 960th Hospital of PLA, Jinan 250031, China; Department of Neurology, Jinzhou Medical University, Jinzhou 121000, China
| | - Huang-Hui Wu
- Department of Anesthesiology, Medical College of Xiamen University, Xiamen 361005, China
| | - Zhuo-Wen Liang
- Institute of Orthopaedics, Xijing Hospital, The Fourth Military Medical University, Xi'an 710032, China
| | - Jin-Tao Fu
- Department of Critical Care Medicine, Affiliated Yanzhou District Hospital of Jining Medical College, Jining 272100, China
| | - Wen-Jun Zhao
- Department of Anatomy, Histology and Embryology, The Fourth Military Medical University, Xi'an 710032, China
| | - Huai-Qiang Hu
- Department of Neurology, the 960th Hospital of PLA, Jinan 250031, China
| | - Hong-Wei Guo
- Department of Neurology, the 960th Hospital of PLA, Jinan 250031, China
| | - Ting Zhang
- Department of Anatomy, Histology and Embryology, The Fourth Military Medical University, Xi'an 710032, China
| | - Ya-Cheng Lu
- Department of Anatomy, Histology and Embryology, The Fourth Military Medical University, Xi'an 710032, China
| | - Shan Jin
- Department of Neurology, the 960th Hospital of PLA, Jinan 250031, China
| | - Xiao-Ling Wang
- Department of Neurology, the 960th Hospital of PLA, Jinan 250031, China
| | - Bing-Zhen Cao
- Department of Neurology, the 960th Hospital of PLA, Jinan 250031, China.
| | - Zhe Wang
- Institute of Orthopaedics, Xijing Hospital, The Fourth Military Medical University, Xi'an 710032, China.
| | - Tan Ding
- Institute of Orthopaedics, Xijing Hospital, The Fourth Military Medical University, Xi'an 710032, China; Department of Anatomy, Histology and Embryology, The Fourth Military Medical University, Xi'an 710032, China.
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Michiels JJ. Aspirin responsive erythromelalgia in JAK2-thrombocythemia and incurable inherited erythrothermalgia in neuropathic Nav1.7 sodium channelopathy: from Mitchell 1878 to Michiels 2017. Expert Opin Orphan Drugs 2016. [DOI: 10.1080/21678707.2017.1270822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Jan Jacques Michiels
- Department of Hematology & Coagulation, Academic Hospital Dijkzigt and Erasmus University, Rotterdam, The Netherlands
- Department of Blood and Coagulation Disorders, University Hospital Antwerp, Edegem, Belgium
- Blood, Coagulation and Vascular Medicine Research Center, Goodheart Institute & Foundation in Nature Medicine & Health, Freedom of Science and Education, European Free University, Erasmus Tower, Rotterdam
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3
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Barbosa C, Xiao Y, Johnson AJ, Xie W, Strong JA, Zhang JM, Cummins TR. FHF2 isoforms differentially regulate Nav1.6-mediated resurgent sodium currents in dorsal root ganglion neurons. Pflugers Arch 2016; 469:195-212. [PMID: 27999940 DOI: 10.1007/s00424-016-1911-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 10/19/2016] [Accepted: 11/20/2016] [Indexed: 10/20/2022]
Abstract
Nav1.6 and Nav1.6-mediated resurgent currents have been implicated in several pain pathologies. However, our knowledge of how fast resurgent currents are modulated in neurons is limited. Our study explored the potential regulation of Nav1.6-mediated resurgent currents by isoforms of fibroblast growth factor homologous factor 2 (FHF2) in an effort to address the gap in our knowledge. FHF2 isoforms colocalize with Nav1.6 in peripheral sensory neurons. Cell line studies suggest that these proteins differentially regulate inactivation. In particular, FHF2A mediates long-term inactivation, a mechanism proposed to compete with the open-channel blocker mechanism that mediates resurgent currents. On the other hand, FHF2B lacks the ability to mediate long-term inactivation and may delay inactivation favoring open-channel block. Based on these observations, we hypothesized that FHF2A limits resurgent currents, whereas FHF2B enhances resurgent currents. Overall, our results suggest that FHF2A negatively regulates fast resurgent current by enhancing long-term inactivation and delaying recovery. In contrast, FHF2B positively regulated resurgent current and did not alter long-term inactivation. Chimeric constructs of FHF2A and Navβ4 (likely the endogenous open channel blocker in sensory neurons) exhibited differential effects on resurgent currents, suggesting that specific regions within FHF2A and Navβ4 have important regulatory functions. Our data also indicate that FHFAs and FHF2B isoform expression are differentially regulated in a radicular pain model and that associated neuronal hyperexcitability is substantially attenuated by a FHFA peptide. As such, these findings suggest that FHF2A and FHF2B regulate resurgent current in sensory neurons and may contribute to hyperexcitability associated with some pain pathologies.
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Affiliation(s)
- Cindy Barbosa
- Department of Pharmacology and Toxicology, Indiana University, Indianapolis, IN, USA.,Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Yucheng Xiao
- Department of Pharmacology and Toxicology, Indiana University, Indianapolis, IN, USA.,Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Andrew J Johnson
- Department of Pharmacology and Toxicology, Indiana University, Indianapolis, IN, USA.,Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Wenrui Xie
- Department of Anesthesiology, University of Cincinnati, Cincinnati, OH, USA
| | - Judith A Strong
- Department of Anesthesiology, University of Cincinnati, Cincinnati, OH, USA
| | - Jun-Ming Zhang
- Department of Anesthesiology, University of Cincinnati, Cincinnati, OH, USA
| | - Theodore R Cummins
- Department of Pharmacology and Toxicology, Indiana University, Indianapolis, IN, USA. .,Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA. .,Department of Biology, Indiana University - Purdue University Indianapolis, Indianapolis, IN, USA.
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4
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Jeevaratnam K, Guzadhur L, Goh YM, Grace AA, Huang CLH. Sodium channel haploinsufficiency and structural change in ventricular arrhythmogenesis. Acta Physiol (Oxf) 2016; 216:186-202. [PMID: 26284956 DOI: 10.1111/apha.12577] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Revised: 06/11/2015] [Accepted: 07/24/2015] [Indexed: 12/19/2022]
Abstract
Normal cardiac excitation involves orderly conduction of electrical activation and recovery dependent upon surface membrane, voltage-gated, sodium (Na(+) ) channel α-subunits (Nav 1.5). We summarize experimental studies of physiological and clinical consequences of loss-of-function Na(+) channel mutations. Of these conditions, Brugada syndrome (BrS) and progressive cardiac conduction defect (PCCD) are associated with sudden, often fatal, ventricular tachycardia (VT) or fibrillation. Mouse Scn5a(+/-) hearts replicate important clinical phenotypes modelling these human conditions. The arrhythmic phenotype is associated not only with the primary biophysical change but also with additional, anatomical abnormalities, in turn dependent upon age and sex, each themselves exerting arrhythmic effects. Available evidence suggests a unified binary scheme for the development of arrhythmia in both BrS and PCCD. Previous biophysical studies suggested that Nav 1.5 deficiency produces a background electrophysiological defect compromising conduction, thereby producing an arrhythmic substrate unmasked by flecainide or ajmaline challenge. More recent reports further suggest a progressive decline in conduction velocity and increase in its dispersion particularly in ageing male Nav 1.5 haploinsufficient compared to WT hearts. This appears to involve a selective appearance of slow conduction at the expense of rapidly conducting pathways with changes in their frequency distributions. These changes were related to increased cardiac fibrosis. It is thus the combination of the structural and biophysical changes both accentuating arrhythmic substrate that may produce arrhythmic tendency. This binary scheme explains the combined requirement for separate, biophysical and structural changes, particularly occurring in ageing Nav 1.5 haploinsufficient males in producing clinical arrhythmia.
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Affiliation(s)
- K. Jeevaratnam
- Faculty of Health and Medical Science; University of Surrey; Guilford UK
- Perdana University - Royal College of Surgeons Ireland; Serdang Selangor Darul Ehsan Malaysia
| | - L. Guzadhur
- Division of Cardiovascular Biology; Department of Biochemistry; University of Cambridge; Cambridge UK
- Niche Science & Technology; Richmond UK
| | - Y. M. Goh
- Department of Preclinical Sciences; Faculty of Veterinary Medicine; University Putra Malaysia; Serdang Selangor Darul Ehsan Malaysia
| | - A. A. Grace
- Division of Cardiovascular Biology; Department of Biochemistry; University of Cambridge; Cambridge UK
| | - C. L.-H. Huang
- Division of Cardiovascular Biology; Department of Biochemistry; University of Cambridge; Cambridge UK
- Physiological Laboratory; University of Cambridge; Cambridge UK
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Verstraelen TE, Ter Bekke RMA, Volders PGA, Masclee AAM, Kruimel JW. The role of the SCN5A-encoded channelopathy in irritable bowel syndrome and other gastrointestinal disorders. Neurogastroenterol Motil 2015; 27:906-13. [PMID: 25898860 DOI: 10.1111/nmo.12569] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Accepted: 03/17/2015] [Indexed: 12/19/2022]
Abstract
BACKGROUND Gastrointestinal functional and motility disorders, like irritable bowel syndrome (IBS), have a high prevalence in the Western population and cause significant morbidity and loss of quality of life leading to considerable costs for health care. A decade ago, it has been demonstrated that interstitial cells of Cajal and intestinal smooth muscle cells, cells important for gastrointestinal motility, express the sodium channel alpha subunit Nav 1.5. In the heart, aberrant variants in this sodium channel, encoded by SCN5A, are linked to inherited arrhythmia syndromes, like the long-QT syndrome type 3 and Brugada syndrome. Mounting data show a possible contribution of SCN5A mutants to gastrointestinal functional and motility disorders. Two percent of IBS patients harbor SCN5A mutations with electrophysiological evidence of loss- and gain-of-function. In addition, gastrointestinal symptoms are more prevalent in cardiac SCN5A-mutation positive patients. PURPOSE This review firstly describes the Nav 1.5 channel and its physiological role in ventricular cardiomyocytes and gastrointestinal cells, then we focus on the involvement of mutant Nav 1.5 in gastrointestinal functional and motility disorders. Future research might uncover novel mutation-specific treatment strategies for SCN5A-encoded gastrointestinal channelopathies.
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Affiliation(s)
- T E Verstraelen
- Division of Gastroenterology-Hepatology, Department of Internal Medicine, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - R M A Ter Bekke
- Department of Cardiology, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - P G A Volders
- Department of Cardiology, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - A A M Masclee
- Division of Gastroenterology-Hepatology, Department of Internal Medicine, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - J W Kruimel
- Division of Gastroenterology-Hepatology, Department of Internal Medicine, Maastricht University Medical Centre, Maastricht, The Netherlands
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Abstract
The voltage sensitive domain (VSD) is a pivotal structure of voltage-gated ion channels (VGICs) and plays an essential role in the generation of electrochemical signals by neurons, striated muscle cells, and endocrine cells. The VSD is not unique to VGICs. Recent studies have shown that a VSD regulates a phosphatase. Similarly, Hv1, a voltage-sensitive protein that lacks an apparent pore domain, is a self-contained voltage sensor that operates as an H⁺ channel. VSDs are formed by four transmembrane helices (S1-S4). The S4 helix is positively charged due to the presence of arginine and lysine residues. It is surrounded by two water crevices that extend into the membrane from both the extracellular and intracellular milieus. A hydrophobic septum disrupts communication between these water crevices thus preventing the permeation of ions. The septum is maintained by interactions between the charged residues of the S4 segment and the gating charge transfer center. Mutating the charged residue of the S4 segment allows the water crevices to communicate and generate gating pore or omega pore. Gating pore currents have been reported to underlie several neuronal and striated muscle channelopathies. Depending on which charged residue on the S4 segment is mutated, gating pores are permeant either at depolarized or hyperpolarized voltages. Gating pores are cation selective and seem to converge toward Eisenmann's first or second selectivity sequences. Most gating pores are blocked by guanidine derivatives as well as trivalent and quadrivalent cations. Gating pores can be used to study the movement of the voltage sensor and could serve as targets for novel small therapeutic molecules.
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Influence of single-nucleotide polymorphisms on deferasirox C trough levels and effectiveness. THE PHARMACOGENOMICS JOURNAL 2014; 15:263-71. [PMID: 25348619 DOI: 10.1038/tpj.2014.65] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 07/30/2014] [Accepted: 09/19/2014] [Indexed: 01/19/2023]
Abstract
Deferasirox (DFX) is the only once-daily oral chelator for iron overload and its pharmacokinetic has been related with response to therapy. Our aim was to evaluate DFX plasma concentrations according to single-nucleotide polymorphisms in genes involved in its metabolism (UGT1A1, UGT1A3, CYP1A1, CYP1A2 and CYP2D6) and elimination (MRP2 and BCRP1). Further aim was to define a plasma concentration cutoff value predicting an adequate response to therapy. Plasma concentrations were determined at the end of dosing interval (C trough) using an high-performance liquid chromatography-ultraviolet method. Allelic discrimination was performed by real-time PCR. C trough levels were influenced by UGT1A1C>T rs887829, CYP1A1C>A rs2606345, CYP1A2A>C rs762551, CYP1A2C>T rs2470890 and MRP2G>A rs2273697 polymorphisms. A DFX plasma efficacy cutoff value of 20,000 ng ml(-1) was identified; CYP1A1C>A rs2606345 AA and CYP1A2C>T rs2470890 TT genotypes may predict this value, suggesting a negative predictive role in therapy efficacy. Our data suggest the feasibility of a pharmacogenetic-based DFX dose personalization.
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Zhang Q, Chibalina MV, Bengtsson M, Groschner LN, Ramracheya R, Rorsman NJG, Leiss V, Nassar MA, Welling A, Gribble FM, Reimann F, Hofmann F, Wood JN, Ashcroft FM, Rorsman P. Na+ current properties in islet α- and β-cells reflect cell-specific Scn3a and Scn9a expression. J Physiol 2014; 592:4677-96. [PMID: 25172946 PMCID: PMC4253470 DOI: 10.1113/jphysiol.2014.274209] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Mouse pancreatic β- and α-cells are equipped with voltage-gated Na+ currents that inactivate over widely different membrane potentials (half-maximal inactivation (V0.5) at −100 mV and −50 mV in β- and α-cells, respectively). Single-cell PCR analyses show that both α- and β-cells have Nav1.3 (Scn3) and Nav1.7 (Scn9a) α subunits, but their relative proportions differ: β-cells principally express Nav1.7 and α-cells Nav1.3. In α-cells, genetically ablating Scn3a reduces the Na+ current by 80%. In β-cells, knockout of Scn9a lowers the Na+ current by >85%, unveiling a small Scn3a-dependent component. Glucagon and insulin secretion are inhibited in Scn3a−/− islets but unaffected in Scn9a-deficient islets. Thus, Nav1.3 is the functionally important Na+ channel α subunit in both α- and β-cells because Nav1.7 is largely inactive at physiological membrane potentials due to its unusually negative voltage dependence of inactivation. Interestingly, the Nav1.7 sequence in brain and islets is identical and yet the V0.5 for inactivation is >30 mV more negative in β-cells. This may indicate the presence of an intracellular factor that modulates the voltage dependence of inactivation.
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Affiliation(s)
- Quan Zhang
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, OX3 7LJ, UK
| | - Margarita V Chibalina
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, OX3 7LJ, UK
| | - Martin Bengtsson
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, OX3 7LJ, UK
| | - Lukas N Groschner
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, OX3 7LJ, UK
| | - Reshma Ramracheya
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, OX3 7LJ, UK
| | - Nils J G Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, OX3 7LJ, UK
| | - Veronika Leiss
- Institut für Pharmakologie und Toxikologie, TU München, Biedersteiner Str. 29, 80802, München, Germany Institut für Pharmakologie und Toxikologie, Eberhard-Karls Universität, Wilhelmstr. 56, 72074, Tübingen, Germany
| | - Mohammed A Nassar
- Molecular Nociception Group, University College London (UCL), Gower Street, London, WC1E 6BT, UK Biomedical Science, University of Sheffield, Sheffield, S10 2TN, UK
| | - Andrea Welling
- Institut für Pharmakologie und Toxikologie, TU München, Biedersteiner Str. 29, 80802, München, Germany
| | - Fiona M Gribble
- Cambridge Institute for Medical Research, University of Cambridge School of Clinical Medicine, Wellcome Trust/MRC Building, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, UK
| | - Frank Reimann
- Cambridge Institute for Medical Research, University of Cambridge School of Clinical Medicine, Wellcome Trust/MRC Building, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, UK
| | - Franz Hofmann
- Institut für Pharmakologie und Toxikologie, TU München, Biedersteiner Str. 29, 80802, München, Germany FOR 923, Institut für Pharmakologie und Toxikologie, TU München, Biedersteiner Str. 29, 80802, München, Germany
| | - John N Wood
- Molecular Nociception Group, University College London (UCL), Gower Street, London, WC1E 6BT, UK
| | - Frances M Ashcroft
- Henry Wellcome Centre for Gene Function, Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, OX3 7LJ, UK Department of Neuroscience and Physiology, Sahlgren's Academy, University of Göteborg, Box 430, SE40530, Göteborg, Sweden
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9
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Amezaga JM, Amtmann A, Biggs CA, Bond T, Gandy CJ, Honsbein A, Karunakaran E, Lawton L, Madsen MA, Minas K, Templeton MR. Biodesalination: a case study for applications of photosynthetic bacteria in water treatment. PLANT PHYSIOLOGY 2014; 164:1661-76. [PMID: 24610748 PMCID: PMC3982732 DOI: 10.1104/pp.113.233973] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Accepted: 03/05/2014] [Indexed: 05/07/2023]
Abstract
Shortage of freshwater is a serious problem in many regions worldwide, and is expected to become even more urgent over the next decades as a result of increased demand for food production and adverse effects of climate change. Vast water resources in the oceans can only be tapped into if sustainable, energy-efficient technologies for desalination are developed. Energization of desalination by sunlight through photosynthetic organisms offers a potential opportunity to exploit biological processes for this purpose. Cyanobacterial cultures in particular can generate a large biomass in brackish and seawater, thereby forming a low-salt reservoir within the saline water. The latter could be used as an ion exchanger through manipulation of transport proteins in the cell membrane. In this article, we use the example of biodesalination as a vehicle to review the availability of tools and methods for the exploitation of cyanobacteria in water biotechnology. Issues discussed relate to strain selection, environmental factors, genetic manipulation, ion transport, cell-water separation, process design, safety, and public acceptance.
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Affiliation(s)
- Jaime M. Amezaga
- School of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom (J.M.A., C.J.G.)
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom (A.A., A.H., M.A.M.)
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield S1 3JD, United Kingdom (C.A.B., E.K.)
- Department of Civil and Environmental Engineering, Imperial College London, London SW7 2AZ, United Kingdom (T.B., M.R.T.); and
- Institute for Innovation, Design and Sustainability, Robert Gordon University, Aberdeen AB10 7AQ, United Kingdom (L.L., K.M.)
| | | | - Catherine A. Biggs
- School of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom (J.M.A., C.J.G.)
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom (A.A., A.H., M.A.M.)
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield S1 3JD, United Kingdom (C.A.B., E.K.)
- Department of Civil and Environmental Engineering, Imperial College London, London SW7 2AZ, United Kingdom (T.B., M.R.T.); and
- Institute for Innovation, Design and Sustainability, Robert Gordon University, Aberdeen AB10 7AQ, United Kingdom (L.L., K.M.)
| | - Tom Bond
- School of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom (J.M.A., C.J.G.)
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom (A.A., A.H., M.A.M.)
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield S1 3JD, United Kingdom (C.A.B., E.K.)
- Department of Civil and Environmental Engineering, Imperial College London, London SW7 2AZ, United Kingdom (T.B., M.R.T.); and
- Institute for Innovation, Design and Sustainability, Robert Gordon University, Aberdeen AB10 7AQ, United Kingdom (L.L., K.M.)
| | - Catherine J. Gandy
- School of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom (J.M.A., C.J.G.)
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom (A.A., A.H., M.A.M.)
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield S1 3JD, United Kingdom (C.A.B., E.K.)
- Department of Civil and Environmental Engineering, Imperial College London, London SW7 2AZ, United Kingdom (T.B., M.R.T.); and
- Institute for Innovation, Design and Sustainability, Robert Gordon University, Aberdeen AB10 7AQ, United Kingdom (L.L., K.M.)
| | - Annegret Honsbein
- School of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom (J.M.A., C.J.G.)
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom (A.A., A.H., M.A.M.)
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield S1 3JD, United Kingdom (C.A.B., E.K.)
- Department of Civil and Environmental Engineering, Imperial College London, London SW7 2AZ, United Kingdom (T.B., M.R.T.); and
- Institute for Innovation, Design and Sustainability, Robert Gordon University, Aberdeen AB10 7AQ, United Kingdom (L.L., K.M.)
| | - Esther Karunakaran
- School of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom (J.M.A., C.J.G.)
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom (A.A., A.H., M.A.M.)
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield S1 3JD, United Kingdom (C.A.B., E.K.)
- Department of Civil and Environmental Engineering, Imperial College London, London SW7 2AZ, United Kingdom (T.B., M.R.T.); and
- Institute for Innovation, Design and Sustainability, Robert Gordon University, Aberdeen AB10 7AQ, United Kingdom (L.L., K.M.)
| | - Linda Lawton
- School of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom (J.M.A., C.J.G.)
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom (A.A., A.H., M.A.M.)
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield S1 3JD, United Kingdom (C.A.B., E.K.)
- Department of Civil and Environmental Engineering, Imperial College London, London SW7 2AZ, United Kingdom (T.B., M.R.T.); and
- Institute for Innovation, Design and Sustainability, Robert Gordon University, Aberdeen AB10 7AQ, United Kingdom (L.L., K.M.)
| | - Mary Ann Madsen
- School of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom (J.M.A., C.J.G.)
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom (A.A., A.H., M.A.M.)
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield S1 3JD, United Kingdom (C.A.B., E.K.)
- Department of Civil and Environmental Engineering, Imperial College London, London SW7 2AZ, United Kingdom (T.B., M.R.T.); and
- Institute for Innovation, Design and Sustainability, Robert Gordon University, Aberdeen AB10 7AQ, United Kingdom (L.L., K.M.)
| | - Konstantinos Minas
- School of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom (J.M.A., C.J.G.)
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom (A.A., A.H., M.A.M.)
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield S1 3JD, United Kingdom (C.A.B., E.K.)
- Department of Civil and Environmental Engineering, Imperial College London, London SW7 2AZ, United Kingdom (T.B., M.R.T.); and
- Institute for Innovation, Design and Sustainability, Robert Gordon University, Aberdeen AB10 7AQ, United Kingdom (L.L., K.M.)
| | - Michael R. Templeton
- School of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom (J.M.A., C.J.G.)
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom (A.A., A.H., M.A.M.)
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield S1 3JD, United Kingdom (C.A.B., E.K.)
- Department of Civil and Environmental Engineering, Imperial College London, London SW7 2AZ, United Kingdom (T.B., M.R.T.); and
- Institute for Innovation, Design and Sustainability, Robert Gordon University, Aberdeen AB10 7AQ, United Kingdom (L.L., K.M.)
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11
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Shan D, Xie Y, Ren G, Yang Z. Attenuated effect of tungsten carbide nanoparticles on voltage-gated sodium current of hippocampal CA1 pyramidal neurons. Toxicol In Vitro 2012; 27:299-304. [PMID: 22954532 DOI: 10.1016/j.tiv.2012.08.025] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2012] [Revised: 07/30/2012] [Accepted: 08/22/2012] [Indexed: 10/27/2022]
Abstract
Nanomaterials and relevant products are now being widely used in the world, and their safety becomes a great concern for the general public. Tungsten carbide nanoparticles (nano-WC) are widely used in metallurgy, aeronautics and astronautics, however our knowledge regarding the influence of nano-WC on neurons is still lacking. The aim of this study was to investigate the impact of nano-WC on tetrodotoxin (TTX)-sensitive voltage-activated sodium current (I(Na)) of hippocampal CA1 pyramidal neurons. Results showed that acute exposure of nano-WC attenuated the peak amplitudes of I(Na) in a concentration-dependent manner. The minimal effective concentration was 10(-5)g/ml. The exposure of nano-WC significantly decreased current amplitudes of the current-voltage curves of I(Na) from -50 to+50 mV, shifted the steady-state activation and inactivation curves of I(Na) negatively and delayed the recovery of I(Na) from inactivation state. After exposure to nano-WC, the peak amplitudes, overshoots and the V-thresholds of action potentials (APs) were markedly reduced. These results suggested that exposure of nano-WC could influence some characteristics of APs evoked from the hippocampal CA1 neurons by modifying the kinetics of voltage-gated sodium channels (VGSCs).
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Affiliation(s)
- Dehong Shan
- College of Medicine Science, Nankai University, Tianjin 300071, China
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12
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Hao S, Bao YM, Zhao RG, Wang HS, Bi J, An LJ, Jiang B. Effects of resibufogenin on voltage-gated sodium channels in cultured rat hippocampal neurons. Neurosci Lett 2011; 501:112-6. [DOI: 10.1016/j.neulet.2011.06.059] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Revised: 06/29/2011] [Accepted: 06/29/2011] [Indexed: 11/16/2022]
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13
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Cai B, Mu X, Gong D, Jiang S, Li J, Meng Q, Bai Y, Liu Y, Wang X, Tan X, Yang B, Lu Y. Difference of sodium currents between pediatric and adult human atrial myocytes: evidence for developmental changes of sodium channels. Int J Biol Sci 2011; 7:708-14. [PMID: 21647304 PMCID: PMC3107490 DOI: 10.7150/ijbs.7.708] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Accepted: 05/25/2011] [Indexed: 02/06/2023] Open
Abstract
Voltage-gated calcium currents and potassium currents were shown to undergo developmental changes in postnatal human and animal cardiomocytes. However, so far, there is no evidence whether sodium currents also presented the developmental changes in postnatal human atrial cells. The aim of this study was to observe age-related changes of sodium currents between pediatric and adult atrial myocytes. Human atrial myocytes were acutely isolated and the whole-cell patch clamp technique was used to record sodium currents isolated from pediatric and adult atrial cardiomocytes. The peak amplitude of sodium currents recorded in adult atrial cells was significantly larger than that in pediatric atrial myocytes. However, there was no significant difference of the activation voltage for peak sodium currents between two kinds of atrial myocytes. The time constants for the activation and inactivation of sodium currents were smaller in adult atria than pediatric atria. The further study revealed that the voltage-dependent inactivation of sodium currents were more slow in adult atrial cardiomyocytes than pediatric atrial cells. A significant difference was also observed in the recovery process of sodium channel from inactivation. In summary, a few significant differences were demonstrated in sodium currents characteristics between pediatric and adult atrial myocytes, which indicates that sodium currents in human atria also undergo developmental changes.
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Affiliation(s)
- Benzhi Cai
- Department of Pharmacology, the State-Province Key Laboratory of Biomedicine, Ministry of Education, Harbin Medical University, and Department of Cardiosurgery, Second Affiliated Hospital of Harbin Medical University, Harbin 150081, China
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14
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Action potentials in primary osteoblasts and in the MG-63 osteoblast-like cell line. J Bioenerg Biomembr 2011; 43:311-22. [PMID: 21523406 DOI: 10.1007/s10863-011-9354-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2011] [Accepted: 04/03/2011] [Indexed: 01/25/2023]
Abstract
Whole-cell patch-clamp analysis revealed a resting membrane potential of -60 mV in primary osteoblasts and in the MG-63 osteoblast-like cells. Depolarization-induced action potentials were characterized by duration of 60 ms, a minimal peak-to-peak distance of 180 ms, a threshold value of -20 mV and a repolarization between the spikes to -45 mV. Expressed channels were characterized by application of voltage pulses between -150 mV and 90 mV in 10 mV steps, from a holding potential of -40 mV. Voltages below -60 mV induced an inward current. Depolarizing voltages above -30 mV evoked two currents: (a) a fast activated and inactivated inward current at voltages between -30 and 30 mV, and (b) a delayed-activated outward current that was induced by voltages above -30 mV. Electrophysiological and pharmacological parameters indicated that hyperpolarization activated strongly rectifying K(+) (K(ir)) channels, whereas depolarization activated tetrodotoxin sensitive voltage gated Na(+) (Na(v)) channels as well as delayed, slowly activated, non-inactivating, and tetraethylammonium sensitive voltage gated K(+) (K(v)) channels. In addition, RT-PCR showed expression of Na(v)1.3, Na(v)1.4, Na(v)1.5, Na(v)1.6, Na(v)1.7, and K(ir)2.1, K(ir)2.3, and K(ir)2.4 as well as K(v)2.1. We conclude that osteoblasts express channels that allow firing of action potentials.
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Wilde AA, Brugada R. Phenotypical Manifestations of Mutations in the Genes Encoding Subunits of the Cardiac Sodium Channel. Circ Res 2011; 108:884-97. [DOI: 10.1161/circresaha.110.238469] [Citation(s) in RCA: 171] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Arthur A.M. Wilde
- From the Heart Research Centre (A.A.M.W.), Department of Clinical and Experimental Cardiology, Academic Medical Center, University Medical Center, University of Amsterdam, The Netherlands; and the Institut d'Investigació Biomèdica Girona-IdIBGi (R.B.), Universitat de Girona, Giona Spain
| | - Ramon Brugada
- From the Heart Research Centre (A.A.M.W.), Department of Clinical and Experimental Cardiology, Academic Medical Center, University Medical Center, University of Amsterdam, The Netherlands; and the Institut d'Investigació Biomèdica Girona-IdIBGi (R.B.), Universitat de Girona, Giona Spain
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16
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Liu Z, Liu S, Ren G, Zhang T, Yang Z. Nano-CuO inhibited voltage-gated sodium current of hippocampal CA1 neurons via reactive oxygen species but independent from G-proteins pathway. J Appl Toxicol 2011; 31:439-45. [DOI: 10.1002/jat.1611] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2010] [Revised: 07/29/2010] [Accepted: 10/08/2010] [Indexed: 01/09/2023]
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Chockalingam P, Rammeloo LA, Postema PG, Hruda J, Clur SAB, Blom NA, Wilde AA. Fever-induced life-threatening arrhythmias in children harboring an SCN5A mutation. Pediatrics 2011; 127:e239-44. [PMID: 21135007 DOI: 10.1542/peds.2010-1688] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Cardiac channelopathies caused by SCN5A mutation are well tolerated by most patients. However, the dramatic presentation of a previously healthy 4-month-old girl with life-threatening arrhythmias and the subsequent findings in the child and her family provide evidence that loss-of-function sodium channel mutations can present very early in life. An SCN5A mutation was detected in the infant, her brother, and their father. Both the siblings manifested recurrent serious arrhythmias during febrile episodes, which followed immunization, as well as fever of nonspecific origin. Management consisted of prompt antipyretic measures, hospitalization with vigorous monitoring during immunization and febrile episodes, and prevention of tachycardia-induced conduction disturbance with β-blockers.
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Affiliation(s)
- Priya Chockalingam
- Department of Cardiology, Heart Failure Research Centre, Academic Medical Centre, Meibergdreef 9, 1105AZ Amsterdam, Netherlands.
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Hund TJ, Koval OM, Li J, Wright PJ, Qian L, Snyder JS, Gudmundsson H, Kline CF, Davidson NP, Cardona N, Rasband MN, Anderson ME, Mohler PJ. A β(IV)-spectrin/CaMKII signaling complex is essential for membrane excitability in mice. J Clin Invest 2010; 120:3508-19. [PMID: 20877009 DOI: 10.1172/jci43621] [Citation(s) in RCA: 210] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2010] [Accepted: 07/28/2010] [Indexed: 02/04/2023] Open
Abstract
Ion channel function is fundamental to the existence of life. In metazoans, the coordinate activities of voltage-gated Na(+) channels underlie cellular excitability and control neuronal communication, cardiac excitation-contraction coupling, and skeletal muscle function. However, despite decades of research and linkage of Na(+) channel dysfunction with arrhythmia, epilepsy, and myotonia, little progress has been made toward understanding the fundamental processes that regulate this family of proteins. Here, we have identified β(IV)-spectrin as a multifunctional regulatory platform for Na(+) channels in mice. We found that β(IV)-spectrin targeted critical structural and regulatory proteins to excitable membranes in the heart and brain. Animal models harboring mutant β(IV)-spectrin alleles displayed aberrant cellular excitability and whole animal physiology. Moreover, we identified a regulatory mechanism for Na(+) channels, via direct phosphorylation by β(IV)-spectrin-targeted calcium/calmodulin-dependent kinase II (CaMKII). Collectively, our data define an unexpected but indispensable molecular platform that determines membrane excitability in the mouse heart and brain.
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Affiliation(s)
- Thomas J Hund
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242, USA.
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Chopra SS, Stroud DM, Watanabe H, Bennett JS, Burns CG, Wells KS, Yang T, Zhong TP, Roden DM. Voltage-gated sodium channels are required for heart development in zebrafish. Circ Res 2010; 106:1342-50. [PMID: 20339120 DOI: 10.1161/circresaha.109.213132] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
RATIONALE Voltage-gated sodium channels initiate action potentials in excitable tissues. Mice in which Scn5A (the predominant sodium channel gene in heart) has been knocked out die early in development with cardiac malformations by mechanisms which have yet to be determined. OBJECTIVE Here we addressed this question by investigating the role of cardiac sodium channels in zebrafish heart development. METHODS AND RESULTS Transcripts of the functionally-conserved Scn5a homologs scn5Laa and scn5Lab were detected in the gastrulating zebrafish embryo and subsequently in the embryonic myocardium. Antisense knockdown of either channel resulted in marked cardiac chamber dysmorphogenesis and perturbed looping. These abnormalities were associated with decreased expression of the myocardial precursor genes nkx2.5, gata4, and hand2 in anterior lateral mesoderm and significant deficits in the production of cardiomyocyte progenitors. These early defects did not appear to result from altered membrane electrophysiology, as prolonged pharmacological blockade of sodium current failed to phenocopy channel knockdown. Moreover, embryos grown in calcium channel blocker-containing medium had hearts that did not beat but developed normally. CONCLUSIONS These findings identify a novel and possibly nonelectrogenic role for cardiac sodium channels in heart development.
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Affiliation(s)
- Sameer S Chopra
- Department of Pharmacology, Vanderbilt University School of Medicine, 2215B Garland Ave, 1275 MRBIV Light Hall, Nashville, TN 37232-0575, USA
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20
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Liu Z, Ren G, Zhang T, Yang Z. Action potential changes associated with the inhibitory effects on voltage-gated sodium current of hippocampal CA1 neurons by silver nanoparticles. Toxicology 2009; 264:179-84. [DOI: 10.1016/j.tox.2009.08.005] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2009] [Revised: 08/02/2009] [Accepted: 08/04/2009] [Indexed: 10/20/2022]
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21
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Jarecki BW, Sheets PL, Xiao Y, Jackson JO, Cummins TR. Alternative splicing of Na(V)1.7 exon 5 increases the impact of the painful PEPD mutant channel I1461T. Channels (Austin) 2009; 3:259-67. [PMID: 19633428 DOI: 10.4161/chan.3.4.9341] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Alternative splicing is known to alter pharmacological sensitivities, kinetics, channel distribution under pathological conditions, and developmental regulation of VGSCs. Mutations that alter channel properties in Na(V)1.7 have been genetically implicated in patients with bouts of extreme pain classified as inherited erythromelalgia (IEM) or paroxysmal extreme pain disorder (PEPD). Furthermore, patients with IEM or PEPD report differential age onsets. A recent study reported that alternative splicing of Na(V)1.7 exon 5 affects ramp current properties. Since IEM and PEPD mutations also alter Na(V)1.7 ramp current properties we speculated that alternative splicing might impact the functional consequences of IEM or PEPD mutations. We compared the effects alternative splicing has on the biophysical properties of Na(V)1.7 wild-type, IEM (I136V) and PEPD (I1461T) channels. Our major findings demonstrate that although the 5A splice variant of the IEM channel had no functional impact, the 5A splice variant of the PEPD channel significantly hyperpolarized the activation curve, slowed deactivation and closed-state inactivation, shifted the ramp current activation to more hyperpolarized potentials, and increased ramp current amplitude. We hypothesize a D1/S3-S4 charged residue difference between the 5N (Asn) and the 5A (Asp) variants within the coding region of exon 5 may contribute to shifts in channel activation and deactivation. Taken together, the additive effects observed on ramp currents from exon 5 splicing and the PEPD mutation (I1461T) are likely to impact the disease phenotype and may offer insight into how alternative splicing may affect specific intramolecular interactions critical for voltage-dependent gating.
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Affiliation(s)
- Brian W Jarecki
- Department of Pharmacology and Toxicology, Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
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22
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Remme CA, Scicluna BP, Verkerk AO, Amin AS, van Brunschot S, Beekman L, Deneer VHM, Chevalier C, Oyama F, Miyazaki H, Nukina N, Wilders R, Escande D, Houlgatte R, Wilde AAM, Tan HL, Veldkamp MW, de Bakker JMT, Bezzina CR. Genetically determined differences in sodium current characteristics modulate conduction disease severity in mice with cardiac sodium channelopathy. Circ Res 2009; 104:1283-92. [PMID: 19407241 DOI: 10.1161/circresaha.109.194423] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Conduction slowing of the electric impulse that drives the heartbeat may evoke lethal cardiac arrhythmias. Mutations in SCN5A, which encodes the pore-forming cardiac sodium channel alpha subunit, are associated with familial arrhythmia syndromes based on conduction slowing. However, disease severity among mutation carriers is highly variable. We hypothesized that genetic modifiers underlie the variability in conduction slowing and disease severity. With the aim of identifying such modifiers, we studied the Scn5a(1798insD/+) mutation in 2 distinct mouse strains, FVB/N and 129P2. In 129P2 mice, the mutation resulted in more severe conduction slowing particularly in the right ventricle (RV) compared to FVB/N. Pan-genomic mRNA expression profiling in the 2 mouse strains uncovered a drastic reduction in mRNA encoding the sodium channel auxiliary subunit beta4 (Scn4b) in 129P2 mice compared to FVB/N. This corresponded to low to undetectable beta4 protein levels in 129P2 ventricular tissue, whereas abundant beta4 protein was detected in FVB/N. Sodium current measurements in isolated myocytes from the 2 mouse strains indicated that sodium channel activation in myocytes from 129P2 mice occurred at more positive potentials compared to FVB/N. Using computer simulations, this difference in activation kinetics was predicted to explain the observed differences in conduction disease severity between the 2 strains. In conclusion, genetically determined differences in sodium current characteristics on the myocyte level modulate disease severity in cardiac sodium channelopathies. In particular, the sodium channel subunit beta4 (SCN4B) may constitute a potential genetic modifier of conduction and cardiac sodium channel disease.
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Affiliation(s)
- Carol Ann Remme
- Heart Failure Research Center, Department of Experimental Cardiology, Academic Medical Center, University of Amsterdam, Room K2-110, PO Box 22700, 1100 DE Amsterdam, The Netherlands.
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23
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Remme CA, Verkerk AO, Hoogaars WMH, Aanhaanen WTJ, Scicluna BP, Annink C, van den Hoff MJB, Wilde AAM, van Veen TAB, Veldkamp MW, de Bakker JMT, Christoffels VM, Bezzina CR. The cardiac sodium channel displays differential distribution in the conduction system and transmural heterogeneity in the murine ventricular myocardium. Basic Res Cardiol 2009; 104:511-22. [PMID: 19255801 PMCID: PMC2722719 DOI: 10.1007/s00395-009-0012-8] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/24/2008] [Revised: 01/30/2009] [Accepted: 02/03/2009] [Indexed: 12/15/2022]
Abstract
Cardiac sodium channels are responsible for conduction in the normal and diseased heart. We aimed to investigate regional and transmural distribution of sodium channel expression and function in the myocardium. Sodium channel Scn5a mRNA and Na(v)1.5 protein distribution was investigated in adult and embryonic mouse heart through immunohistochemistry and in situ hybridization. Functional sodium channel availability in subepicardial and subendocardial myocytes was assessed using patch-clamp technique. Adult and embryonic (ED14.5) mouse heart sections showed low expression of Na(v)1.5 in the HCN4-positive sinoatrial and atrioventricular nodes. In contrast, high expression levels of Na(v)1.5 were observed in the HCN4-positive and Cx43-negative AV or His bundle, bundle branches and Purkinje fibers. In both ventricles, a transmural gradient was observed, with a low Na(v)1.5 labeling intensity in the subepicardium as compared to the subendocardium. Similar Scn5a mRNA expression patterns were observed on in situ hybridization of embryonic and adult tissue. Maximal action potential upstroke velocity was significantly lower in subepicardial myocytes (mean +/- SEM 309 +/- 32 V/s; n = 14) compared to subendocardial myocytes (394 +/- 32 V/s; n = 11; P < 0.05), indicating decreased sodium channel availability in subepicardium compared to subendocardium. Scn5a and Na(v)1.5 show heterogeneous distribution patterns within the cardiac conduction system and across the ventricular wall. This differential distribution of the cardiac sodium channel may have profound consequences for conduction disease phenotypes and arrhythmogenesis in the setting of sodium channel disease.
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Affiliation(s)
- C A Remme
- Heart Failure Research Center, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
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Vacher H, Mohapatra DP, Trimmer JS. Localization and targeting of voltage-dependent ion channels in mammalian central neurons. Physiol Rev 2008; 88:1407-47. [PMID: 18923186 DOI: 10.1152/physrev.00002.2008] [Citation(s) in RCA: 348] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The intrinsic electrical properties and the synaptic input-output relationships of neurons are governed by the action of voltage-dependent ion channels. The localization of specific populations of ion channels with distinct functional properties at discrete sites in neurons dramatically impacts excitability and synaptic transmission. Molecular cloning studies have revealed a large family of genes encoding voltage-dependent ion channel principal and auxiliary subunits, most of which are expressed in mammalian central neurons. Much recent effort has focused on determining which of these subunits coassemble into native neuronal channel complexes, and the cellular and subcellular distributions of these complexes, as a crucial step in understanding the contribution of these channels to specific aspects of neuronal function. Here we review progress made on recent studies aimed to determine the cellular and subcellular distribution of specific ion channel subunits in mammalian brain neurons using in situ hybridization and immunohistochemistry. We also discuss the repertoire of ion channel subunits in specific neuronal compartments and implications for neuronal physiology. Finally, we discuss the emerging mechanisms for determining the discrete subcellular distributions observed for many neuronal ion channels.
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Affiliation(s)
- Helene Vacher
- Department of Neurobiology, Physiology, and Behavior, College of Biological Sciences, University of California, Davis, California 95616-8519, USA
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25
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Cardiac sodium channel overlap syndromes: different faces of SCN5A mutations. Trends Cardiovasc Med 2008; 18:78-87. [PMID: 18436145 DOI: 10.1016/j.tcm.2008.01.002] [Citation(s) in RCA: 163] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2007] [Revised: 12/29/2007] [Accepted: 01/07/2008] [Indexed: 12/19/2022]
Abstract
Cardiac sodium channel dysfunction caused by mutations in the SCN5A gene is associated with a number of relatively uncommon arrhythmia syndromes, including long-QT syndrome type 3 (LQT3), Brugada syndrome, conduction disease, sinus node dysfunction, and atrial standstill, which potentially lead to fatal arrhythmias in relatively young individuals. Although these various arrhythmia syndromes were originally considered separate entities, recent evidence indicates more overlap in clinical presentation and biophysical defects of associated mutant channels than previously appreciated. Various SCN5A mutations are now known to present with mixed phenotypes, a presentation that has become known as "overlap syndrome of cardiac sodium channelopathy." In many cases, multiple biophysical defects of single SCN5A mutations are suspected to underlie the overlapping clinical manifestations. Here, we provide an overview of current knowledge on SCN5A mutations associated with sodium channel overlap syndromes and discuss a possible role for modifiers in determining disease expressivity in the individual patient.
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Jarecki BW, Sheets PL, Jackson JO, Cummins TR. Paroxysmal extreme pain disorder mutations within the D3/S4-S5 linker of Nav1.7 cause moderate destabilization of fast inactivation. J Physiol 2008; 586:4137-53. [PMID: 18599537 DOI: 10.1113/jphysiol.2008.154906] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Single-point missense mutations in the peripheral neuronal voltage-gated sodium channel Nav1.7 are implicated in the painful inherited neuropathy paroxysmal extreme pain disorder (PEPD). The Nav1.7 PEPD mutations are located in regions of the channel suggested to play important roles in fast inactivation. PEPD mutations in the putative inactivation gate have been reported to significantly impair fast inactivation, resulting in pronounced persistent currents. However, PEPD mutations in the S4-S5 linker of domain 3 (D3/S4-S5) had not been characterized and the roles of specific residues in this linker in channel gating are unclear. We functionally characterized two of the D3/S4-S5 PEPD mutations (V1298F and V1299F) and compared their effects on gating to an adjacent non-PEPD mutation (V1300F) and the I1461T PEPD mutation, located in the putative inactivation gate. The primary effect of the V1298F and V1299F mutations is to shift the voltage dependence of fast inactivation by approximately 20 mV in the depolarizing direction. We observed a similar effect with the PEPD mutation I1461T. Interestingly, while all three PEPD mutations increased persistent currents, the relative amplitudes (approximately 6% of peak) were much smaller than previously reported for the I1461T mutation. In contrast, the main effect of the V1300F mutation was a depolarizing shift in the voltage dependence of activation. These data demonstrate that (1) mutations within D3/S4-S5 affect inactivation of Nav1.7 in a residue-specific manner and (2) disruption of the fast-inactivated state by PEPD mutations can be more moderate than previously indicated, which has important implications for the pathophysiology of PEPD.
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Affiliation(s)
- Brian W Jarecki
- Department of Pharmacology and Toxicology, Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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27
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Wilde AAM, Coronel R. The complexity of genotype-phenotype relations associated with loss-of-function sodium channel mutations and the role of in silico studies. Am J Physiol Heart Circ Physiol 2008; 295:H8-9. [PMID: 18502906 DOI: 10.1152/ajpheart.00494.2008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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