1
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Subcellular dynamics and functional activity of the cleaved intracellular domain of the Na + channel β1 subunit. J Biol Chem 2022; 298:102174. [PMID: 35752364 PMCID: PMC9304784 DOI: 10.1016/j.jbc.2022.102174] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 06/08/2022] [Accepted: 06/16/2022] [Indexed: 11/24/2022] Open
Abstract
The voltage-gated Na+ channel β1 subunit, encoded by SCN1B, regulates cell surface expression and gating of α subunits and participates in cell adhesion. β1 is cleaved by α/β and γ-secretases, releasing an extracellular domain and intracellular domain (ICD), respectively. Abnormal SCN1B expression/function is linked to pathologies including epilepsy, cardiac arrhythmia, and cancer. In this study, we sought to determine the effect of secretase cleavage on β1 function in breast cancer cells. Using a series of GFP-tagged β1 constructs, we show that β1-GFP is mainly retained intracellularly, particularly in the endoplasmic reticulum and endolysosomal pathway, and accumulates in the nucleus. Reduction in endosomal β1-GFP levels occurred following γ-secretase inhibition, implicating endosomes and/or the preceding plasma membrane as important sites for secretase processing. Using live-cell imaging, we also report β1ICD-GFP accumulation in the nucleus. Furthermore, β1-GFP and β1ICD-GFP both increased Na+ current, whereas β1STOP-GFP, which lacks the ICD, did not, thus highlighting that the β1-ICD is necessary and sufficient to increase Na+ current measured at the plasma membrane. Importantly, although the endogenous Na+ current expressed in MDA-MB-231 cells is tetrodotoxin (TTX)-resistant (carried by Nav1.5), the Na+ current increased by β1-GFP or β1ICD-GFP was TTX-sensitive. Finally, we found β1-GFP increased mRNA levels of the TTX-sensitive α subunits SCN1A/Nav1.1 and SCN9A/Nav1.7. Taken together, this work suggests that the β1-ICD is a critical regulator of α subunit function in cancer cells. Our data further highlight that γ-secretase may play a key role in regulating β1 function in breast cancer.
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2
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Pharmacological Dissection of the Crosstalk between Na V and Ca V Channels in GH3b6 Cells. Int J Mol Sci 2022; 23:ijms23020827. [PMID: 35055012 PMCID: PMC8775721 DOI: 10.3390/ijms23020827] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 01/07/2022] [Accepted: 01/09/2022] [Indexed: 02/01/2023] Open
Abstract
Thanks to the crosstalk between Na+ and Ca2+ channels, Na+ and Ca2+ homeostasis interplay in so-called excitable cells enables the generation of action potential in response to electrical stimulation. Here, we investigated the impact of persistent activation of voltage-gated Na+ (NaV) channels by neurotoxins, such as veratridine (VTD), on intracellular Ca2+ concentration ([Ca2+]i) in a model of excitable cells, the rat pituitary GH3b6 cells, in order to identify the molecular actors involved in Na+-Ca2+ homeostasis crosstalk. By combining RT-qPCR, immunoblotting, immunocytochemistry, and patch-clamp techniques, we showed that GH3b6 cells predominantly express the NaV1.3 channel subtype, which likely endorses their voltage-activated Na+ currents. Notably, these Na+ currents were blocked by ICA-121431 and activated by the β-scorpion toxin Tf2, two selective NaV1.3 channel ligands. Using Fura-2, we showed that VTD induced a [Ca2+]i increase. This effect was suppressed by the selective NaV channel blocker tetrodotoxin, as well by the selective L-type CaV channel (LTCC) blocker nifedipine. We also evidenced that crobenetine, a NaV channel blocker, abolished VTD-induced [Ca2+]i elevation, while it had no effects on LTCC. Altogether, our findings highlight a crosstalk between NaV and LTCC in GH3b6 cells, providing a new insight into the mode of action of neurotoxins.
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3
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Alsaloum M, Labau JIR, Sosniak D, Zhao P, Almomani R, Gerrits M, Hoeijmakers JGJ, Lauria G, Faber CG, Waxman SG, Dib-Hajj S. A novel gain-of-function sodium channel β2 subunit mutation in idiopathic small fiber neuropathy. J Neurophysiol 2021; 126:827-839. [PMID: 34320850 DOI: 10.1152/jn.00184.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Small fiber neuropathy (SFN) is a common condition affecting thinly myelinated Aδ and unmyelinated C fibers, often resulting in excruciating pain and dysautonomia. SFN has been associated with several conditions, but a significant number of cases have no discernible cause. Recent genetic studies have identified potentially pathogenic gain-of-function mutations in several the pore-forming voltage-gated sodium channel α subunits (NaVs) in a subset of patients with SFN, but the auxiliary sodium channel β subunits have been less implicated in the development of the disease. β subunits modulate NaV trafficking and gating, and several mutations have been linked to epilepsy and cardiac dysfunction. Recently, we provided the first evidence for the contribution of a mutation in the β2-subunit to pain in human painful diabetic neuropathy. Here, we provide the first evidence for the involvement of a sodium channel β subunit mutation in the pathogenesis of SFN with no other known causes. We show, through current-clamp analysis, that the newly-identified Y69H variant of the β2 subunit induces neuronal hyperexcitability in dorsal root ganglion neurons, lowering the threshold for action potential firing and allowing for increased repetitive action potential spiking. Underlying the hyperexcitability induced by the β2-Y69H variant, we demonstrate an upregulation in tetrodotoxin-sensitive, but not tetrodotoxin-resistant sodium currents. This provides the first evidence for the involvement of β2 subunits in SFN and strengthens the link between sodium channel β subunits and the development of neuropathic pain in humans.
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Affiliation(s)
- Matthew Alsaloum
- Department of Neurology, Yale University School of Medicine, New Haven, CT, United States.,Center for Neuroscience and Regeneration Research, Yale University, West Haven, CT, United States.,Center for Rehabilitation Research, VA Connecticut Healthcare System, West Haven, CT, United States.,Yale Medical Scientist Training Program, Yale School of Medicine, New Haven, CT, United States.,Interdepartmental Neuroscience Program, Yale School of Medicine, New Haven, CT, United States
| | - Julie I R Labau
- Department of Neurology, Yale University School of Medicine, New Haven, CT, United States.,Center for Neuroscience and Regeneration Research, Yale University, West Haven, CT, United States.,Center for Rehabilitation Research, VA Connecticut Healthcare System, West Haven, CT, United States.,Department of Genetics and Cell Biology, Clinical Genomics Unit, Maastricht University, Maastricht, the Netherlands.,Department of Neurology, Maastricht University Medical Centre+, Maastricht, the Netherlands
| | - Daniel Sosniak
- Department of Neurology, Yale University School of Medicine, New Haven, CT, United States.,Center for Neuroscience and Regeneration Research, Yale University, West Haven, CT, United States.,Center for Rehabilitation Research, VA Connecticut Healthcare System, West Haven, CT, United States
| | - Peng Zhao
- Department of Neurology, Yale University School of Medicine, New Haven, CT, United States.,Center for Neuroscience and Regeneration Research, Yale University, West Haven, CT, United States.,Center for Rehabilitation Research, VA Connecticut Healthcare System, West Haven, CT, United States
| | - Rowida Almomani
- Department of Genetics and Cell Biology, Clinical Genomics Unit, Maastricht University, Maastricht, the Netherlands.,Department of Medical Laboratory Sciences, Jordan University of Science and Technology, Irbid, Jordan
| | - Monique Gerrits
- Department of Clinical Genetics, Maastricht University Medical Centre+, Maastricht, the Netherlands
| | | | - Giuseppe Lauria
- Neuroalgology Unit, IRCCS Foundation "Carlo Besta" Neurological Institute, Milan, Italy.,Department of Biomedical and Clinical Sciences "Luigi Sacco," University of Milan, Milan, Italy
| | - Catherina G Faber
- Department of Neurology, Maastricht University Medical Centre+, Maastricht, the Netherlands
| | - Stephen G Waxman
- Department of Neurology, Yale University School of Medicine, New Haven, CT, United States.,Center for Neuroscience and Regeneration Research, Yale University, West Haven, CT, United States.,Center for Rehabilitation Research, VA Connecticut Healthcare System, West Haven, CT, United States
| | - Sulayman Dib-Hajj
- Department of Neurology, Yale University School of Medicine, New Haven, CT, United States.,Center for Neuroscience and Regeneration Research, Yale University, West Haven, CT, United States.,Center for Rehabilitation Research, VA Connecticut Healthcare System, West Haven, CT, United States
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4
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Le Cann K, Meents JE, Sudha Bhagavath Eswaran V, Dohrn MF, Bott R, Maier A, Bialer M, Hautvast P, Erickson A, Rolke R, Rothermel M, Körner J, Kurth I, Lampert A. Assessing the impact of pain-linked Nav1.7 variants: An example of two variants with no biophysical effect. Channels (Austin) 2021; 15:208-228. [PMID: 33487118 PMCID: PMC7833769 DOI: 10.1080/19336950.2020.1870087] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Mutations in the voltage-gated sodium channel Nav1.7 are linked to human pain. The Nav1.7/N1245S variant was described before in several patients suffering from primary erythromelalgia and/or olfactory hypersensitivity. We have identified this variant in a pain patient and a patient suffering from severe and life-threatening orthostatic hypotension. In addition, we report a female patient suffering from muscle pain and carrying the Nav1.7/E1139K variant. We tested both Nav1.7 variants by whole-cell voltage-clamp recordings in HEK293 cells, revealing a slightly enhanced current density for the N1245S variant when co-expressed with the β1 subunit. This effect was counteracted by an enhanced slow inactivation. Both variants showed similar voltage dependence of activation and steady-state fast inactivation, as well as kinetics of fast inactivation, deactivation, and use-dependency compared to WT Nav1.7. Finally, homology modeling revealed that the N1245S substitution results in different intramolecular interaction partners. Taken together, these experiments do not point to a clear pathogenic effect of either the N1245S or E1139K variant and suggest they may not be solely responsible for the patients’ pain symptoms. As discussed previously for other variants, investigations in heterologous expression systems may not sufficiently mimic the pathophysiological situation in pain patients, and single nucleotide variants in other genes or modulatory proteins are necessary for these specific variants to show their effect. Our findings stress that biophysical investigations of ion channel mutations need to be evaluated with care and should preferably be supplemented with studies investigating the mutations in their context, ideally in human sensory neurons.
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Affiliation(s)
- Kim Le Cann
- Institute of Physiology, RWTH Aachen University Hospital , Aachen, Germany
| | - Jannis E Meents
- Institute of Physiology, RWTH Aachen University Hospital , Aachen, Germany
| | | | - Maike F Dohrn
- Department of Neurology, Medical Faculty, RWTH Aachen University Hospital , Aachen, Germany
| | - Raya Bott
- Institute of Physiology, RWTH Aachen University Hospital , Aachen, Germany
| | - Andrea Maier
- Department of Neurology, Medical Faculty, RWTH Aachen University Hospital , Aachen, Germany
| | - Martin Bialer
- Division of Clinical Metabolism of Medical Genetics and Human Genomics at Northwell Health System , New-York, United States
| | - Petra Hautvast
- Institute of Physiology, RWTH Aachen University Hospital , Aachen, Germany
| | - Andelain Erickson
- Institute of Physiology, RWTH Aachen University Hospital , Aachen, Germany
| | - Roman Rolke
- Department for Palliative Care, Medical Faculty, RWTH Aachen University , Aachen, Germany
| | - Markus Rothermel
- Department of Chemosensation, AG Neuromodulation, Institute for Biology II, RWTH Aachen University , Aachen, 52074, Germany
| | - Jannis Körner
- Institute of Physiology, RWTH Aachen University Hospital , Aachen, Germany.,Department of Anaesthesiology, Medical Faculty, RWTH Aachen University , Aachen, Germany
| | - Ingo Kurth
- Institute of Human Genetics, Medical Faculty, RWTH Aachen University Hospital , Aachen, Germany
| | - Angelika Lampert
- Institute of Physiology, RWTH Aachen University Hospital , Aachen, Germany
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5
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Eagles DA, Chow CY, King GF. Fifteen years of Na
V
1.7 channels as an analgesic target: Why has excellent in vitro pharmacology not translated into in vivo analgesic efficacy? Br J Pharmacol 2020; 179:3592-3611. [DOI: 10.1111/bph.15327] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 09/14/2020] [Accepted: 10/23/2020] [Indexed: 12/16/2022] Open
Affiliation(s)
- David A. Eagles
- Institute for Molecular Bioscience The University of Queensland St Lucia QLD Australia
| | - Chun Yuen Chow
- Institute for Molecular Bioscience The University of Queensland St Lucia QLD Australia
| | - Glenn F. King
- Institute for Molecular Bioscience The University of Queensland St Lucia QLD Australia
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6
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Alsaloum M, Estacion M, Almomani R, Gerrits MM, Bönhof GJ, Ziegler D, Malik R, Ferdousi M, Lauria G, Merkies IS, Faber CG, Dib-Hajj S, Waxman SG. A gain-of-function sodium channel β2-subunit mutation in painful diabetic neuropathy. Mol Pain 2020; 15:1744806919849802. [PMID: 31041876 PMCID: PMC6510061 DOI: 10.1177/1744806919849802] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Diabetes mellitus is a global challenge with many diverse health sequelae, of which diabetic peripheral neuropathy is one of the most common. A substantial number of patients with diabetic peripheral neuropathy develop chronic pain, but the genetic and epigenetic factors that predispose diabetic peripheral neuropathy patients to develop neuropathic pain are poorly understood. Recent targeted genetic studies have identified mutations in α-subunits of voltage-gated sodium channels (Navs) in patients with painful diabetic peripheral neuropathy. Mutations in proteins that regulate trafficking or functional properties of Navs could expand the spectrum of patients with Nav-related peripheral neuropathies. The auxiliary sodium channel β-subunits (β1–4) have been reported to increase current density, alter inactivation kinetics, and modulate subcellular localization of Nav. Mutations in β-subunits have been associated with several diseases, including epilepsy, cancer, and diseases of the cardiac conducting system. However, mutations in β-subunits have never been shown previously to contribute to neuropathic pain. We report here a patient with painful diabetic peripheral neuropathy and negative genetic screening for mutations in SCN9A, SCN10A, and SCN11A—genes encoding sodium channel α-subunit that have been previously linked to the development of neuropathic pain. Genetic analysis revealed an aspartic acid to asparagine mutation, D109N, in the β2-subunit. Functional analysis using current-clamp revealed that the β2-D109N rendered dorsal root ganglion neurons hyperexcitable, especially in response to repetitive stimulation. Underlying the hyperexcitability induced by the β2-subunit mutation, as evidenced by voltage-clamp analysis, we found a depolarizing shift in the voltage dependence of Nav1.7 fast inactivation and reduced use-dependent inhibition of the Nav1.7 channel.
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Affiliation(s)
- Matthew Alsaloum
- 1 Department of Neurology, Yale University School of Medicine, New Haven, CT, USA.,2 Center for Neuroscience and Regeneration Research, Veterans Affairs Medical Center, West Haven, CT, USA.,3 Interdepartmental Neuroscience Program, Yale University School of Medicine, New Haven, CT, USA
| | - Mark Estacion
- 1 Department of Neurology, Yale University School of Medicine, New Haven, CT, USA.,2 Center for Neuroscience and Regeneration Research, Veterans Affairs Medical Center, West Haven, CT, USA
| | - Rowida Almomani
- 4 Department of Clinical Genomics, University Medical Center Maastricht, Maastricht, the Netherlands.,5 Department of Medical Laboratory Sciences, Jordan University of Science and Technology, Irbid, Jordan
| | - Monique M Gerrits
- 4 Department of Clinical Genomics, University Medical Center Maastricht, Maastricht, the Netherlands.,6 Department of Neurology, University Medical Centre Maastricht, Maastricht, the Netherlands
| | - Gidon J Bönhof
- 7 Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research at Heinrich Heine University, Düsseldorf, Germany
| | - Dan Ziegler
- 7 Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research at Heinrich Heine University, Düsseldorf, Germany.,1 8German Center for Diabetes Research, München-Neuherberg, Germany.,9 Division of Endocrinology and Diabetology, Medical Faculty, Heinrich Heine University, Düsseldorf, Germany
| | - Rayaz Malik
- 10 Weill Cornell Medicine-Qatar, Doha, Qatar.,11 Division of Diabetes, Endocrinology and Gastroenterology, Institute of Human Development, University of Manchester, Manchester, UK
| | - Maryam Ferdousi
- 11 Division of Diabetes, Endocrinology and Gastroenterology, Institute of Human Development, University of Manchester, Manchester, UK
| | - Giuseppe Lauria
- 12 Neuroalgology Unit, IRCCS Foundation "Carlo Besta" Neurological Institute, Milan, Italy.,13 Department of Biomedical and Clinical Sciences "Luigi Sacco," University of Milan, Milan, Italy
| | - Ingemar Sj Merkies
- 6 Department of Neurology, University Medical Centre Maastricht, Maastricht, the Netherlands.,14 Department of Neurology, St. Elisabeth Hospital, Willemstad, Curaçao
| | - Catharina G Faber
- 6 Department of Neurology, University Medical Centre Maastricht, Maastricht, the Netherlands
| | - Sulayman Dib-Hajj
- 1 Department of Neurology, Yale University School of Medicine, New Haven, CT, USA.,2 Center for Neuroscience and Regeneration Research, Veterans Affairs Medical Center, West Haven, CT, USA
| | - Stephen G Waxman
- 1 Department of Neurology, Yale University School of Medicine, New Haven, CT, USA.,2 Center for Neuroscience and Regeneration Research, Veterans Affairs Medical Center, West Haven, CT, USA
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7
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Chew LA, Bellampalli SS, Dustrude ET, Khanna R. Mining the Na v1.7 interactome: Opportunities for chronic pain therapeutics. Biochem Pharmacol 2019; 163:9-20. [PMID: 30699328 DOI: 10.1016/j.bcp.2019.01.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Accepted: 01/24/2019] [Indexed: 12/14/2022]
Abstract
The peripherally expressed voltage-gated sodium NaV1.7 (gene SCN9A) channel boosts small stimuli to initiate firing of pain-signaling dorsal root ganglia (DRG) neurons and facilitates neurotransmitter release at the first synapse within the spinal cord. Mutations in SCN9A produce distinct human pain syndromes. Widely acknowledged as a "gatekeeper" of pain, NaV1.7 has been the focus of intense investigation but, to date, no NaV1.7-selective drugs have reached the clinic. Elegant crystallographic studies have demonstrated the potential of designing highly potent and selective NaV1.7 compounds but their therapeutic value remains untested. Transcriptional silencing of NaV1.7 by a naturally expressed antisense transcript has been reported in rodents and humans but whether this represents a viable opportunity for designing NaV1.7 therapeutics is currently unknown. The demonstration that loss of NaV1.7 function is associated with upregulation of endogenous opioids and potentiation of mu- and delta-opioid receptor activities, suggests that targeting only NaV1.7 may be insufficient for analgesia. However, the link between opioid-dependent analgesic mechanisms and function of sodium channels and intracellular sodium-dependent signaling remains controversial. Thus, additional new targets - regulators, modulators - are needed. In this context, we mine the literature for the known interactome of NaV1.7 with a focus on protein interactors that affect the channel's trafficking or link it to opioid signaling. As a case study, we present antinociceptive evidence of allosteric regulation of NaV1.7 by the cytosolic collapsin response mediator protein 2 (CRMP2). Throughout discussions of these possible new targets, we offer thoughts on the therapeutic implications of modulating NaV1.7 function in chronic pain.
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Affiliation(s)
- Lindsey A Chew
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ 85724, USA
| | - Shreya S Bellampalli
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ 85724, USA
| | - Erik T Dustrude
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA; Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Rajesh Khanna
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ 85724, USA; Graduate Interdisciplinary Program in Neuroscience, College of Medicine, University of Arizona, Tucson, AZ, USA; The Center for Innovation in Brain Sciences, The University of Arizona Health Sciences, Tucson, AZ 85724, USA.
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8
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Yamanishi T, Koizumi H, Navarro MA, Milescu LS, Smith JC. Kinetic properties of persistent Na + current orchestrate oscillatory bursting in respiratory neurons. J Gen Physiol 2018; 150:1523-1540. [PMID: 30301870 PMCID: PMC6219691 DOI: 10.1085/jgp.201812100] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 08/14/2018] [Accepted: 09/19/2018] [Indexed: 01/08/2023] Open
Abstract
The rhythmic pattern of breathing depends on the pre-Bötzinger complex (preBötC) in the brainstem, a vital circuit that contains a population of neurons with intrinsic oscillatory bursting behavior. Here, we investigate the specific kinetic properties that enable voltage-gated sodium channels to establish oscillatory bursting in preBötC inspiratory neurons, which exhibit an unusually large persistent Na+ current (INaP). We first characterize the kinetics of INaP in neonatal rat brainstem slices in vitro, using whole-cell patch-clamp and computational modeling, and then test the contribution of INaP to rhythmic bursting in live neurons, using the dynamic clamp technique. We provide evidence that subthreshold activation, persistence at suprathreshold potentials, slow inactivation, and slow recovery from inactivation are kinetic features of INaP that regulate all aspects of intrinsic rhythmic bursting in preBötC neurons. The slow and cumulative inactivation of INaP during the burst active phase controls burst duration and termination, while the slow recovery from inactivation controls the duration of the interburst interval. To demonstrate this mechanism, we develop a Markov state model of INaP that explains a comprehensive set of voltage clamp data. By adding or subtracting a computer-generated INaP from a live neuron via dynamic clamp, we are able to convert nonbursters into intrinsic bursters, and vice versa. As a control, we test a model with inactivation features removed. Adding noninactivating INaP into nonbursters results in a pattern of random transitions between sustained firing and quiescence. The relative amplitude of INaP is the key factor that separates intrinsic bursters from nonbursters and can change the fraction of intrinsic bursters in the preBötC. INaP could thus be an important target for regulating network rhythmogenic properties.
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Affiliation(s)
- Tadashi Yamanishi
- Cellular and Systems Neurobiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD.,The First Department of Oral and Maxillofacial Surgery, Osaka University Graduate School of Dentistry, Osaka, Japan
| | - Hidehiko Koizumi
- Cellular and Systems Neurobiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
| | - Marco A Navarro
- Division of Biological Sciences, University of Missouri, Columbia, MO
| | - Lorin S Milescu
- Division of Biological Sciences, University of Missouri, Columbia, MO
| | - Jeffrey C Smith
- Cellular and Systems Neurobiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
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9
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Loss-of-function of Nav1.8/D1639N linked to human pain can be rescued by lidocaine. Pflugers Arch 2018; 470:1787-1801. [PMID: 30099632 DOI: 10.1007/s00424-018-2189-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 07/25/2018] [Accepted: 07/27/2018] [Indexed: 01/31/2023]
Abstract
Mutations in voltage-gated sodium channels are associated with altered pain perception in humans. Most of these mutations studied to date present with a direct and intuitive link between the altered electrophysiological function of the channel and the phenotype of the patient. In this study, we characterize a variant of Nav1.8, D1639N, which has been previously identified in a patient suffering from the chronic pain syndrome "small fiber neuropathy". Using a heterologous expression system and patch-clamp analysis, we show that Nav1.8/D1639N reduces current density without altering biophysical gating properties of Nav1.8. Therefore, the D1639N variant causes a loss-of-function of the Nav1.8 sodium channel in a patient suffering from chronic pain. Using immunocytochemistry and biochemical approaches, we show that Nav1.8/D1639N impairs trafficking of the channel to the cell membrane. Neither co-expression of β1 or β3 subunit, nor overnight incubation at 27 °C rescued current density of the D1639N variant. On the other hand, overnight incubation with lidocaine fully restored current density of Nav1.8/D1639N most likely by overcoming the trafficking defect, whereas phenytoin failed to do so. Since lidocaine rescues the loss-of-function of Nav1.8/D1639N, it may offer a future therapeutic option for the patient carrying this variant. These results demonstrate that the D1639N variant, identified in a patient suffering from chronic pain, causes loss-of-function of the channel due to impaired cell surface trafficking and that this trafficking defect can be rescued by lidocaine.
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10
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Wang J, Ou SW, Wang YJ. Distribution and function of voltage-gated sodium channels in the nervous system. Channels (Austin) 2017; 11:534-554. [PMID: 28922053 DOI: 10.1080/19336950.2017.1380758] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Voltage-gated sodium channels (VGSCs) are the basic ion channels for neuronal excitability, which are crucial for the resting potential and the generation and propagation of action potentials in neurons. To date, at least nine distinct sodium channel isoforms have been detected in the nervous system. Recent studies have identified that voltage-gated sodium channels not only play an essential role in the normal electrophysiological activities of neurons but also have a close relationship with neurological diseases. In this study, the latest research findings regarding the structure, type, distribution, and function of VGSCs in the nervous system and their relationship to neurological diseases, such as epilepsy, neuropathic pain, brain tumors, neural trauma, and multiple sclerosis, are reviewed in detail.
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Affiliation(s)
- Jun Wang
- a Department of Neurosurgery , The First Hospital of China Medical University , Shenyang , P.R. China
| | - Shao-Wu Ou
- a Department of Neurosurgery , The First Hospital of China Medical University , Shenyang , P.R. China
| | - Yun-Jie Wang
- a Department of Neurosurgery , The First Hospital of China Medical University , Shenyang , P.R. China
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11
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Tosti E, Boni R, Gallo A. µ-Conotoxins Modulating Sodium Currents in Pain Perception and Transmission: A Therapeutic Potential. Mar Drugs 2017; 15:E295. [PMID: 28937587 PMCID: PMC5666403 DOI: 10.3390/md15100295] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 09/12/2017] [Accepted: 09/20/2017] [Indexed: 12/27/2022] Open
Abstract
The Conus genus includes around 500 species of marine mollusks with a peculiar production of venomous peptides known as conotoxins (CTX). Each species is able to produce up to 200 different biological active peptides. Common structure of CTX is the low number of amino acids stabilized by disulfide bridges and post-translational modifications that give rise to different isoforms. µ and µO-CTX are two isoforms that specifically target voltage-gated sodium channels. These, by inducing the entrance of sodium ions in the cell, modulate the neuronal excitability by depolarizing plasma membrane and propagating the action potential. Hyperexcitability and mutations of sodium channels are responsible for perception and transmission of inflammatory and neuropathic pain states. In this review, we describe the current knowledge of µ-CTX interacting with the different sodium channels subtypes, the mechanism of action and their potential therapeutic use as analgesic compounds in the clinical management of pain conditions.
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Affiliation(s)
- Elisabetta Tosti
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Naples, Italy.
| | - Raffaele Boni
- Department of Sciences, University of Basilicata, 75100 Potenza, Italy.
| | - Alessandra Gallo
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Naples, Italy.
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12
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Fischer BD, Ho C, Kuzin I, Bottaro A, O’Leary ME. Chronic exposure to tumor necrosis factor in vivo induces hyperalgesia, upregulates sodium channel gene expression and alters the cellular electrophysiology of dorsal root ganglion neurons. Neurosci Lett 2017; 653:195-201. [DOI: 10.1016/j.neulet.2017.05.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 05/01/2017] [Accepted: 05/03/2017] [Indexed: 12/25/2022]
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13
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Lee SJ, Kim DH, Hahn SJ, Waxman SG, Choi JS. Mechanism of inhibition by chlorpromazine of the human pain threshold sodium channel, Nav1.7. Neurosci Lett 2017; 639:1-7. [DOI: 10.1016/j.neulet.2016.12.051] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Revised: 12/15/2016] [Accepted: 12/20/2016] [Indexed: 12/12/2022]
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14
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Israel MR, Tay B, Deuis JR, Vetter I. Sodium Channels and Venom Peptide Pharmacology. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2017; 79:67-116. [PMID: 28528674 DOI: 10.1016/bs.apha.2017.01.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Venomous animals including cone snails, spiders, scorpions, anemones, and snakes have evolved a myriad of components in their venoms that target the opening and/or closing of voltage-gated sodium channels to cause devastating effects on the neuromuscular systems of predators and prey. These venom peptides, through design and serendipity, have not only contributed significantly to our understanding of sodium channel pharmacology and structure, but they also represent some of the most phyla- and isoform-selective molecules that are useful as valuable tool compounds and drug leads. Here, we review our understanding of the basic function of mammalian voltage-gated sodium channel isoforms as well as the pharmacology of venom peptides that act at these key transmembrane proteins.
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Affiliation(s)
- Mathilde R Israel
- Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia
| | - Bryan Tay
- Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia
| | - Jennifer R Deuis
- Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia.
| | - Irina Vetter
- Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia; School of Pharmacy, The University of Queensland, Brisbane, QLD, Australia.
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Barbosa C, Cummins TR. Unusual Voltage-Gated Sodium Currents as Targets for Pain. CURRENT TOPICS IN MEMBRANES 2016; 78:599-638. [PMID: 27586296 DOI: 10.1016/bs.ctm.2015.12.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Pain is a serious health problem that impacts the lives of many individuals. Hyperexcitability of peripheral sensory neurons contributes to both acute and chronic pain syndromes. Because voltage-gated sodium currents are crucial to the transmission of electrical signals in peripheral sensory neurons, the channels that underlie these currents are attractive targets for pain therapeutics. Sodium currents and channels in peripheral sensory neurons are complex. Multiple-channel isoforms contribute to the macroscopic currents in nociceptive sensory neurons. These different isoforms exhibit substantial variations in their kinetics and pharmacology. Furthermore, sodium current complexity is enhanced by an array of interacting proteins that can substantially modify the properties of voltage-gated sodium channels. Resurgent sodium currents, atypical currents that can enhance recovery from inactivation and neuronal firing, are increasingly being recognized as playing potentially important roles in sensory neuron hyperexcitability and pain sensations. Here we discuss unusual sodium channels and currents that have been identified in nociceptive sensory neurons, describe what is known about the molecular determinants of the complex sodium currents in these neurons. Finally, we provide an overview of therapeutic strategies to target voltage-gated sodium currents in nociceptive neurons.
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Affiliation(s)
- C Barbosa
- Indiana University School of Medicine, Indianapolis, IN, United States
| | - T R Cummins
- Indiana University School of Medicine, Indianapolis, IN, United States
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Bourdin CM, Guérineau NC, Murillo L, Quinchard S, Dong K, Legros C. Molecular and functional characterization of a novel sodium channel TipE-like auxiliary subunit from the American cockroach Periplaneta americana. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2015; 66:136-144. [PMID: 26524962 DOI: 10.1016/j.ibmb.2015.10.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Revised: 10/14/2015] [Accepted: 10/16/2015] [Indexed: 06/05/2023]
Abstract
In Drosophila melanogaster, the functions of voltage-gated sodium (Nav) channels are modulated by TipE and its orthologs. Here, we describe a novel TipE homolog of the American cockroach, Periplaneta americana, called PaTipE. Like DmTipE, PaTipE mRNAs are ubiquitously expressed. Surprisingly, PaTipE mRNA was undetectable in neurosecretory cells identified as dorsal unpaired median neurons. Phylogenetic analysis placed this new sequence in TipE clade, indicating an independent evolution from a common ancestor. Contrary to previous reports, our data indicate that the auxiliary subunits of insect Nav channels are very distant from the mammalian BKCa auxiliary subunits. To decipher the functional roles of PaTipE, we characterized the gating properties of DmNav1-1 channels co-expressed with DmTipE or PaTipE, in Xenopus oocytes. Compared to DmTipE, PaTipE increased Na(+) currents by a 4.2-fold. The voltage-dependence of steady-state fast inactivation of DmNav1-1/PaTipE channels was shifted by 5.8 mV to more negative potentials than that of DmNav1-1/DmTipE channels. DmNav1-1/PaTipE channels recovered 3.2-fold slower from the fast-inactivated state than DmNav1-1/DmTipE channels. In conclusion, this study supports that the insect Nav auxiliary subunits share functional features with their mammalian counterparts, although structurally and phylogenetically distant.
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Affiliation(s)
- Céline M Bourdin
- Laboratoire Récepteurs et Canaux Ioniques Membranaires (RCIM), UPRES EA 2647/USC, INRA 1330, SFR QUASAV n° 4207, Université d'Angers, UFR Sciences, 2 boulevard Lavoisier, F-49045, Angers Cedex, France
| | - Nathalie C Guérineau
- Laboratoire de Biologie Neurovasculaire et Mitochondriale Intégrée, CNRS UMR 6214, INSERM U1083, UFR de Sciences Médicales, Université d'Angers, rue Haute de Reculée, F-49045, Angers Cedex, France; Institut de Génomique Fonctionnelle, UMR CNRS 5203, INSERM U661, Université de Montpellier, 141 rue de la Cardonille, F-34094, Montpellier Cedex 5, France
| | - Laurence Murillo
- Laboratoire Récepteurs et Canaux Ioniques Membranaires (RCIM), UPRES EA 2647/USC, INRA 1330, SFR QUASAV n° 4207, Université d'Angers, UFR Sciences, 2 boulevard Lavoisier, F-49045, Angers Cedex, France; Laboratoire LIttoral ENvironnement et Sociétés (LIENSs), UMR 7266 CNRS Université de La Rochelle, Institut du Littoral et de l'Environnement, 2 rue Olympe de Gouges, F-17000, La Rochelle, France
| | - Sophie Quinchard
- Laboratoire Récepteurs et Canaux Ioniques Membranaires (RCIM), UPRES EA 2647/USC, INRA 1330, SFR QUASAV n° 4207, Université d'Angers, UFR Sciences, 2 boulevard Lavoisier, F-49045, Angers Cedex, France
| | - Ke Dong
- Department of Entomology, Genetics and Neuroscience Programs, Michigan State University, East Lansing, 106 CIPS, MI 48824, USA
| | - Christian Legros
- Laboratoire de Biologie Neurovasculaire et Mitochondriale Intégrée, CNRS UMR 6214, INSERM U1083, UFR de Sciences Médicales, Université d'Angers, rue Haute de Reculée, F-49045, Angers Cedex, France.
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Barbosa C, Tan ZY, Wang R, Xie W, Strong JA, Patel RR, Vasko MR, Zhang JM, Cummins TR. Navβ4 regulates fast resurgent sodium currents and excitability in sensory neurons. Mol Pain 2015; 11:60. [PMID: 26408173 PMCID: PMC4582632 DOI: 10.1186/s12990-015-0063-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 09/10/2015] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Increased electrical activity in peripheral sensory neurons including dorsal root ganglia (DRG) and trigeminal ganglia neurons is an important mechanism underlying pain. Voltage gated sodium channels (VGSC) contribute to the excitability of sensory neurons and are essential for the upstroke of action potentials. A unique type of VGSC current, resurgent current (INaR), generates an inward current at repolarizing voltages through an alternate mechanism of inactivation referred to as open-channel block. INaRs are proposed to enable high frequency firing and increased INaRs in sensory neurons are associated with pain pathologies. While Nav1.6 has been identified as the main carrier of fast INaR, our understanding of the mechanisms that contribute to INaR generation is limited. Specifically, the open-channel blocker in sensory neurons has not been identified. Previous studies suggest Navβ4 subunit mediates INaR in central nervous system neurons. The goal of this study was to determine whether Navβ4 regulates INaR in DRG sensory neurons. RESULTS Our immunocytochemistry studies show that Navβ4 expression is highly correlated with Nav1.6 expression predominantly in medium-large diameter rat DRG neurons. Navβ4 knockdown decreased endogenous fast INaR in medium-large diameter neurons as measured with whole-cell voltage clamp. Using a reduced expression system in DRG neurons, we isolated recombinant human Nav1.6 sodium currents in rat DRG neurons and found that overexpression of Navβ4 enhanced Nav1.6 INaR generation. By contrast neither overexpression of Navβ2 nor overexpression of a Navβ4-mutant, predicted to be an inactive form of Navβ4, enhanced Nav1.6 INaR generation. DRG neurons transfected with wild-type Navβ4 exhibited increased excitability with increases in both spontaneous activity and evoked activity. Thus, Navβ4 overexpression enhanced INaR and excitability, whereas knockdown or expression of mutant Navβ4 decreased INaR generation. CONCLUSION INaRs are associated with inherited and acquired pain disorders. However, our ability to selectively target and study this current has been hindered due to limited understanding of how it is generated in sensory neurons. This study identified Navβ4 as an important regulator of INaR and excitability in sensory neurons. As such, Navβ4 is a potential target for the manipulation of pain sensations.
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Affiliation(s)
- Cindy Barbosa
- Department of Pharmacology and Toxicology, Indiana University, Indianapolis, IN, USA. .,Department of Pharmacology and Toxicology, Stark Neurosciences Research Institute, 320 West 25th Street, NB-414F, Indianapolis, IN, 46202-2266, USA.
| | - Zhi-Yong Tan
- Department of Pharmacology and Toxicology, Indiana University, Indianapolis, IN, USA. .,Department of Pharmacology and Toxicology, Stark Neurosciences Research Institute, 320 West 25th Street, NB-414F, Indianapolis, IN, 46202-2266, USA.
| | - Ruizhong Wang
- Department of Pharmacology and Toxicology, Indiana University, 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.
| | - Reesha R Patel
- Medical Neuroscience Graduate Program, Indiana University School of Medicine, Indianapolis, IN, USA. .,Department of Pharmacology and Toxicology, Stark Neurosciences Research Institute, 320 West 25th Street, NB-414F, Indianapolis, IN, 46202-2266, USA.
| | - Michael R Vasko
- Department of Pharmacology and Toxicology, Indiana University, Indianapolis, IN, USA. .,Department of Pharmacology and Toxicology, Stark Neurosciences Research Institute, 320 West 25th Street, NB-414F, Indianapolis, IN, 46202-2266, 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. .,Department of Pharmacology and Toxicology, Stark Neurosciences Research Institute, 320 West 25th Street, NB-414F, Indianapolis, IN, 46202-2266, USA.
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Namadurai S, Yereddi NR, Cusdin FS, Huang CLH, Chirgadze DY, Jackson AP. A new look at sodium channel β subunits. Open Biol 2015; 5:140192. [PMID: 25567098 PMCID: PMC4313373 DOI: 10.1098/rsob.140192] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Voltage-gated sodium (Nav) channels are intrinsic plasma membrane proteins that initiate the action potential in electrically excitable cells. They are a major focus of research in neurobiology, structural biology, membrane biology and pharmacology. Mutations in Nav channels are implicated in a wide variety of inherited pathologies, including cardiac conduction diseases, myotonic conditions, epilepsy and chronic pain syndromes. Drugs active against Nav channels are used as local anaesthetics, anti-arrhythmics, analgesics and anti-convulsants. The Nav channels are composed of a pore-forming α subunit and associated β subunits. The β subunits are members of the immunoglobulin (Ig) domain family of cell-adhesion molecules. They modulate multiple aspects of Nav channel behaviour and play critical roles in controlling neuronal excitability. The recently published atomic resolution structures of the human β3 and β4 subunit Ig domains open a new chapter in the study of these molecules. In particular, the discovery that β3 subunits form trimers suggests that Nav channel oligomerization may contribute to the functional properties of some β subunits.
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Affiliation(s)
- Sivakumar Namadurai
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK
| | - Nikitha R Yereddi
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK
| | - Fiona S Cusdin
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK
| | | | - Dimitri Y Chirgadze
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK
| | - Antony P Jackson
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK
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19
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Structure and function of μ-conotoxins, peptide-based sodium channel blockers with analgesic activity. Future Med Chem 2015; 6:1677-98. [PMID: 25406007 DOI: 10.4155/fmc.14.107] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
μ-Conotoxins block voltage-gated sodium channels (VGSCs) and compete with tetrodotoxin for binding to the sodium conductance pore. Early efforts identified µ-conotoxins that preferentially blocked the skeletal muscle subtype (NaV1.4). However, the last decade witnessed a significant increase in the number of µ-conotoxins and the range of VGSC subtypes inhibited (NaV1.2, NaV1.3 or NaV1.7). Twenty µ-conotoxin sequences have been identified to date and structure-activity relationship studies of several of these identified key residues responsible for interactions with VGSC subtypes. Efforts to engineer-in subtype specificity are driven by in vivo analgesic and neuromuscular blocking activities. This review summarizes structural and pharmacological studies of µ-conotoxins, which show promise for development of selective blockers of NaV1.2, and perhaps also NaV1.1,1.3 or 1.7.
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20
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Kwong K, Carr MJ. Voltage-gated sodium channels. Curr Opin Pharmacol 2015; 22:131-9. [PMID: 26043074 DOI: 10.1016/j.coph.2015.04.007] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Revised: 04/21/2015] [Accepted: 04/29/2015] [Indexed: 12/11/2022]
Abstract
Voltage-gated sodium channels play a key role in the transmission of sensory information about the status of organs in the periphery. Sensory fibers contain a heterogeneous yet specific distribution of voltage-gated sodium channel isoforms. Major efforts by industry and academic groups are underway to develop medicines that interrupt inappropriate signaling for a number of clinical indications by taking advantage of this specific distribution of channel isoforms. This review highlights recent advances in the study of human channelopathies, animal toxins and channel structure that may facilitate the development of selective voltage-gated sodium channel blockers.
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21
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Zhang Z, Schmelz M, Segerdahl M, Quiding H, Centerholt C, Juréus A, Carr TH, Whiteley J, Salter H, Kvernebo MS, Ørstavik K, Helås T, Kleggetveit IP, Lunden LK, Jørum E. Exonic mutations in SCN9A (NaV1.7) are found in a minority of patients with erythromelalgia. Scand J Pain 2014; 5:217-225. [DOI: 10.1016/j.sjpain.2014.09.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Accepted: 09/03/2014] [Indexed: 10/24/2022]
Abstract
Abstract
Background and aim
“Gain-of-function” mutations in voltage-gated sodium channel NaV1.7 have been linked to erythromelalgia (EM), characterized by painful hot and red hands and feet. We investigated the proportion of patients with EM that carry a mutation in NaV1.7 or in other pain-related genes and studied possible clinical differences.
Methods
In this study, 48 patients with EM were screened for mutations in a total of 29 candidate genes, including all sodium channel subunits, transient receptor potential channels (TRPA1, TRPV1, TRPM8), neurotrophic factors (NGF, NGFR, BDNF, GDNF, NTRK1 and WNK1) and other known pain-related genes (CACNG2, KCNS1, COMT, P2RX3, TAC1, TACR1), using a combination of next generation sequencing and classical Sanger sequencing.
Results
In 7/48 patients protein-modifying mutations of NaV1.7 (P187L, I228M, I848T (n = 4) and N1245S) were identified. Patients with the I848T mutation could be identified clinically based on early onset and severity of the disease. In contrast, there were no clinical characteristics that differentiated the other patients with NaV1.7 mutation from those patients without. We also found more than twenty rare protein-modifying genetic variants in the genes coding for sodium channels (NaV1.8, NaV1.9, NaV1.6, NaV1.5, NaV2.1, SCN1B, SCN3B), transient receptor potential channel (TRPA1, TRPV1), and other pain-related targets (WNK1 and NGFR).
Conclusion
We conclude that functionally characterized mutations of NaV1.7 (I848T) are present only in a minority of patient with EM. Albeit the majority of patients (27/48) carried rare protein-modifying mutations the vast majority of those will most probably not be causally linked to their disease.
Implications
The key question remaining to be solved is the possible role of rare variants of NaV1.8, NaV1.9, or beta-subunits in provoking chronic pain conditions or even EM.
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Affiliation(s)
| | - Martin Schmelz
- Department of Anesthesiology Mannheim , Heidelberg University , Heidelberg , Germany
| | - Märta Segerdahl
- AstraZeneca R&D , Södertälje , Sweden
- Department of Physiology and Pharmacology , Karolinska Institute , Stockholm , Sweden
| | | | | | | | | | | | - Hugh Salter
- AstraZeneca Translational Science Centre , Department of Clinical Neuroscience , Karolinska Institutet , Karolinska , Sweden
| | | | - Kristin Ørstavik
- Section of Clinical Neurophysiology , Department of Neurology , Oslo University Hospital-Rikshospitalet , Oslo , Norway
| | - Tormod Helås
- Section of Clinical Neurophysiology , Department of Neurology , Oslo University Hospital-Rikshospitalet , Oslo , Norway
| | - Inge-Petter Kleggetveit
- Section of Clinical Neurophysiology , Department of Neurology , Oslo University Hospital-Rikshospitalet , Oslo , Norway
| | - Lars Kristian Lunden
- Section of Clinical Neurophysiology , Department of Neurology , Oslo University Hospital-Rikshospitalet , Oslo , Norway
| | - Ellen Jørum
- Section of Clinical Neurophysiology , Department of Neurology , Oslo University Hospital-Rikshospitalet , Oslo , Norway
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Zhang MM, Wilson MJ, Gajewiak J, Rivier JE, Bulaj G, Olivera BM, Yoshikami D. Pharmacological fractionation of tetrodotoxin-sensitive sodium currents in rat dorsal root ganglion neurons by μ-conotoxins. Br J Pharmacol 2014; 169:102-14. [PMID: 23351163 DOI: 10.1111/bph.12119] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Revised: 12/18/2012] [Accepted: 12/27/2012] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND AND PURPOSE Adult rat dorsal root ganglion (DRG) neurons normally express transcripts for five isoforms of the α-subunit of voltage-gated sodium channels: NaV 1.1, 1.6, 1.7, 1.8 and 1.9. Tetrodotoxin (TTX) readily blocks all but NaV 1.8 and 1.9, and pharmacological agents that discriminate among the TTX-sensitive NaV 1-isoforms are scarce. Recently, we used the activity profile of a panel of μ-conotoxins in blocking cloned rodent NaV 1-isoforms expressed in Xenopus laevis oocytes to conclude that action potentials of A- and C-fibres in rat sciatic nerve were, respectively, mediated primarily by NaV 1.6 and NaV 1.7. EXPERIMENTAL APPROACH We used three μ-conotoxins, μ-TIIIA, μ-PIIIA and μ-SmIIIA, applied individually and in combinations, to pharmacologically differentiate the TTX-sensitive INa of voltage-clamped neurons acutely dissociated from adult rat DRG. We examined only small and large neurons whose respective INa were >50% and >80% TTX-sensitive. KEY RESULTS In both small and large neurons, the ability of the toxins to block TTX-sensitive INa was μ-TIIIA < μ-PIIIA < μ-SmIIIA, with the latter blocking ≳90%. Comparison of the toxin-susceptibility profiles of the neuronal INa with recently acquired profiles of rat NaV 1-isoforms, co-expressed with various NaV β-subunits in X. laevis oocytes, were consistent: NaV 1.1, 1.6 and 1.7 could account for all of the TTX-sensitive INa , with NaV 1.1 < NaV 1.6 < NaV 1.7 for small neurons and NaV 1.7 < NaV 1.1 < NaV 1.6 for large neurons. CONCLUSIONS AND IMPLICATIONS Combinations of μ-conotoxins can be used to determine the probable NaV 1-isoforms underlying the INa in DRG neurons. Preliminary experiments with sympathetic neurons suggest that this approach is extendable to other neurons.
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Affiliation(s)
- Min-Min Zhang
- Department of Biology, University of Utah, Salt Lake City, UT 84112, USA
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A disulfide tether stabilizes the block of sodium channels by the conotoxin μO§-GVIIJ. Proc Natl Acad Sci U S A 2014; 111:2758-63. [PMID: 24497506 DOI: 10.1073/pnas.1324189111] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
A cone snail venom peptide, μO§-conotoxin GVIIJ from Conus geographus, has a unique posttranslational modification, S-cysteinylated cysteine, which makes possible formation of a covalent tether of peptide to its target Na channels at a distinct ligand-binding site. μO§-conotoxin GVIIJ is a 35-aa peptide, with 7 cysteine residues; six of the cysteines form 3 disulfide cross-links, and one (Cys24) is S-cysteinylated. Due to limited availability of native GVIIJ, we primarily used a synthetic analog whose Cys24 was S-glutathionylated (abbreviated GVIIJSSG). The peptide-channel complex is stabilized by a disulfide tether between Cys24 of the peptide and Cys910 of rat (r) NaV1.2. A mutant channel of rNaV1.2 lacking a cysteine near the pore loop of domain II (C910L), was >10(3)-fold less sensitive to GVIIJSSG than was wild-type rNaV1.2. In contrast, although rNaV1.5 was >10(4)-fold less sensitive to GVIIJSSG than NaV1.2, an rNaV1.5 mutant with a cysteine in the homologous location, rNaV1.5[L869C], was >10(3)-fold more sensitive than wild-type rNaV1.5. The susceptibility of rNaV1.2 to GVIIJSSG was significantly altered by treating the channels with thiol-oxidizing or disulfide-reducing agents. Furthermore, coexpression of rNaVβ2 or rNaVβ4, but not that of rNaVβ1 or rNaVβ3, protected rNaV1.1 to -1.7 (excluding NaV1.5) against block by GVIIJSSG. Thus, GVIIJ-related peptides may serve as probes for both the redox state of extracellular cysteines and for assessing which NaVβ- and NaVα-subunits are present in native neurons.
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24
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Zhang MM, Wilson MJ, Azam L, Gajewiak J, Rivier JE, Bulaj G, Olivera BM, Yoshikami D. Co-expression of Na(V)β subunits alters the kinetics of inhibition of voltage-gated sodium channels by pore-blocking μ-conotoxins. Br J Pharmacol 2013; 168:1597-610. [PMID: 23146020 DOI: 10.1111/bph.12051] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Revised: 10/19/2012] [Accepted: 10/24/2012] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND AND PURPOSE Voltage-gated sodium channels (VGSCs) are assembled from two classes of subunits, a pore-bearing α-subunit (NaV 1) and one or two accessory β-subunits (NaV βs). Neurons in mammals can express one or more of seven isoforms of NaV 1 and one or more of four isoforms of NaV β. The peptide μ-conotoxins, like the guanidinium alkaloids tetrodotoxin (TTX) and saxitoxin (STX), inhibit VGSCs by blocking the pore in NaV 1. Hitherto, the effects of NaV β-subunit co-expression on the activity of these toxins have not been comprehensively assessed. EXPERIMENTAL APPROACH Four μ-conotoxins (μ-TIIIA, μ-PIIIA, μ-SmIIIA and μ-KIIIA), TTX and STX were tested against NaV 1.1, 1.2, 1.6 or 1.7, each co-expressed in Xenopus laevis oocytes with one of NaV β1, β2, β3 or β4 and, for NaV 1.7, binary combinations of thereof. KEY RESULTS Co-expression of NaV β-subunits modifies the block by μ-conotoxins: in general, NaV β1 or β3 co-expression tended to increase kon (in the most extreme instance by ninefold), whereas NaV β2 or β4 co-expression decreased kon (in the most extreme instance by 240-fold). In contrast, the block by TTX and STX was only minimally, if at all, affected by NaV β-subunit co-expression. Tests of NaV β1 : β2 chimeras co-expressed with NaV 1.7 suggest that the extracellular portion of the NaV β subunit is largely responsible for altering μ-conotoxin kinetics. CONCLUSIONS AND IMPLICATIONS These results are the first indication that NaV β subunit co-expression can markedly influence μ-conotoxin binding and, by extension, the outer vestibule of the pore of VGSCs. μ-Conotoxins could, in principle, be used to pharmacologically probe the NaV β subunit composition of endogenously expressed VGSCs.
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Affiliation(s)
- Min-Min Zhang
- Department of Biology, University of Utah, Salt Lake City, UT, USA
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25
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Desaphy JF, Chahine M. Recent advances in voltage-gated sodium channels, their pharmacology, and related diseases. Front Pharmacol 2013; 4:52. [PMID: 23616770 PMCID: PMC3629309 DOI: 10.3389/fphar.2013.00052] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Accepted: 04/04/2013] [Indexed: 12/02/2022] Open
Affiliation(s)
- Jean-François Desaphy
- Section of Pharmacology, Department of Pharmacy and Drug Sciences, University of Bari - Aldo Moro Bari, Italy
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Moldovan M, Alvarez S, Romer Rosberg M, Krarup C. Axonal voltage-gated ion channels as pharmacological targets for pain. Eur J Pharmacol 2013; 708:105-12. [PMID: 23500193 DOI: 10.1016/j.ejphar.2013.03.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Accepted: 03/04/2013] [Indexed: 12/19/2022]
Abstract
Upon peripheral nerve injury (caused by trauma or disease process) axons of the dorsal root ganglion (DRG) somatosensory neurons have the ability to sprout and regrow/remyelinate to reinnervate distant target tissue or form a tangled scar mass called a neuroma. This regenerative response can become maladaptive leading to a persistent and debilitating pain state referred to as chronic pain corresponding to the clinical description of neuropathic/chronic inflammatory pain. There is little agreement to what causes peripheral chronic pain other than hyperactivity of the nociceptive DRG neurons which ultimately depends on the function of voltage-gated ion channels. This review focuses on the pharmacological modulators of voltage-gated ion channels known to be present on axonal membrane which represents by far the largest surface of DRG neurons. Blockers of voltage-gated Na(+) channels, openers of voltage-gated K(+) channels and blockers of hyperpolarization-activated cyclic nucleotide-gated channels that were found to reduce neuronal activity were also found to be effective in neuropathic and inflammatory pain states. The isoforms of these channels present on nociceptive axons have limited specificity. The rationale for considering axonal voltage-gated ion channels as targets for pain treatment comes from the accumulating evidence that chronic pain states are associated with a dysregulation of these channels that could alter their specificity and make them more susceptible to pharmacological modulation. This drives the need for further development of subtype-specific voltage-gated ion channels modulators, as well as clinically available neurophysiological techniques for monitoring axonal ion channel function in peripheral nerves.
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Affiliation(s)
- Mihai Moldovan
- Institute of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark.
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Mercier A, Clément R, Harnois T, Bourmeyster N, Faivre JF, Findlay I, Chahine M, Bois P, Chatelier A. The β1-subunit of Na(v)1.5 cardiac sodium channel is required for a dominant negative effect through α-α interaction. PLoS One 2012; 7:e48690. [PMID: 23133651 PMCID: PMC3486797 DOI: 10.1371/journal.pone.0048690] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Accepted: 10/01/2012] [Indexed: 12/03/2022] Open
Abstract
Brugada syndrome (BrS) is an inherited autosomal dominant cardiac channelopathy. Several mutations on the cardiac sodium channel Nav1.5 which are responsible for BrS lead to misfolded proteins that do not traffic properly to the plasma membrane. In order to mimic patient heterozygosity, a trafficking defective mutant, R1432G was co-expressed with Wild Type (WT) Nav1.5 channels in HEK293T cells. This mutant significantly decreased the membrane Na current density when it was co-transfected with the WT channel. This dominant negative effect did not result in altered biophysical properties of Nav1.5 channels. Luminometric experiments revealed that the expression of mutant proteins induced a significant reduction in membrane expression of WT channels. Interestingly, we have found that the auxiliary Na channel β1-subunit was essential for this dominant negative effect. Indeed, the absence of the β1-subunit prevented the decrease in WT sodium current density and surface proteins associated with the dominant negative effect. Co-immunoprecipitation experiments demonstrated a physical interaction between Na channel α-subunits. This interaction occurred only when the β1-subunit was present. Our findings reveal a new role for β1-subunits in cardiac voltage-gated sodium channels by promoting α-α subunit interaction which can lead to a dominant negative effect when one of the α-subunits shows a trafficking defective mutation.
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Affiliation(s)
- Aurélie Mercier
- Institut de Physiologie et Biologie Cellulaires, FRE 3511, CNRS/Université de Poitiers, Pôle Biologie Santé, Poitiers, France
| | - Romain Clément
- Institut de Physiologie et Biologie Cellulaires, FRE 3511, CNRS/Université de Poitiers, Pôle Biologie Santé, Poitiers, France
| | - Thomas Harnois
- Institut de Physiologie et Biologie Cellulaires, FRE 3511, CNRS/Université de Poitiers, Pôle Biologie Santé, Poitiers, France
- CHU de Poitiers, Poitiers, France
| | - Nicolas Bourmeyster
- Institut de Physiologie et Biologie Cellulaires, FRE 3511, CNRS/Université de Poitiers, Pôle Biologie Santé, Poitiers, France
- CHU de Poitiers, Poitiers, France
| | - Jean-François Faivre
- Institut de Physiologie et Biologie Cellulaires, FRE 3511, CNRS/Université de Poitiers, Pôle Biologie Santé, Poitiers, France
| | - Ian Findlay
- Institut de Physiologie et Biologie Cellulaires, FRE 3511, CNRS/Université de Poitiers, Pôle Biologie Santé, Poitiers, France
- Laboratoire de Physiologie des Cellules Cardiaques et Vasculaires, Institut de Physiologie et Biologie Cellulaires, FRE 3511 CNRS, Université François-Rabelais, Faculté des Sciences, Tours, France
| | - Mohamed Chahine
- Institut universitaire en santé mentale de Québec, Université Laval, Québec, Québec, Canada
| | - Patrick Bois
- Institut de Physiologie et Biologie Cellulaires, FRE 3511, CNRS/Université de Poitiers, Pôle Biologie Santé, Poitiers, France
| | - Aurélien Chatelier
- Institut de Physiologie et Biologie Cellulaires, FRE 3511, CNRS/Université de Poitiers, Pôle Biologie Santé, Poitiers, France
- * E-mail:
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Yereddi NR, Cusdin FS, Namadurai S, Packman LC, Monie TP, Slavny P, Clare JJ, Powell AJ, Jackson AP. The immunoglobulin domain of the sodium channel β3 subunit contains a surface-localized disulfide bond that is required for homophilic binding. FASEB J 2012; 27:568-80. [PMID: 23118027 PMCID: PMC3583845 DOI: 10.1096/fj.12-209445] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The β subunits of voltage-gated sodium (Nav) channels possess an extracellular immunoglobulin (Ig) domain that is related to the L1 family of cell-adhesion molecules (CAMs). Here we show that in HEK293 cells, secretion of the free Ig domain of the β3 subunit is reduced significantly when it is coexpressed with the full-length β3 and β1 subunits but not with the β2 subunit. Using immunoprecipitation, we show that the β3 subunit can mediate trans homophilic-binding via its Ig domain and that the β3-Ig domain can associate heterophilically with the β1 subunit. Evolutionary tracing analysis and structural modeling identified a cluster of surface-localized amino acids fully conserved between the Ig domains of all known β3 and β1 sequences. A notable feature of this conserved surface cluster is the presence of two adjacent cysteine residues that previously we have suggested may form a disulfide bond. We now confirm the presence of the disulfide bond in β3 using mass spectrometry, and we show that its integrity is essential for the association of the full-length, membrane-anchored β3 subunit with itself. However, selective reduction of this surface disulfide bond did not inhibit homophilic binding of the purified β3-Ig domain in free solution. Hence, the disulfide bond itself is unlikely to be part of the homophilic binding site. Rather, we suggest that its integrity ensures the Ig domain of the membrane-tethered β3 subunit adopts the correct orientation for productive association to occur in vivo.—Yereddi, N. R., Cusdin, F. S., Namadurai, S., Packman, L. C., Monie, T. P., Slavny, P., Clare, J. C., Powell, A. J., Jackson, A. P. The immunoglobulin domain of the sodium channel β3 subunit contains a surface-localized disulfide bond that is required for homophilic binding.
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Tetrodotoxin (TTX) as a therapeutic agent for pain. Mar Drugs 2012; 10:281-305. [PMID: 22412801 PMCID: PMC3296997 DOI: 10.3390/md10020281] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2011] [Revised: 01/19/2012] [Accepted: 01/19/2012] [Indexed: 12/19/2022] Open
Abstract
Tetrodotoxin (TTX) is a potent neurotoxin that blocks voltage-gated sodium channels (VGSCs). VGSCs play a critical role in neuronal function under both physiological and pathological conditions. TTX has been extensively used to functionally characterize VGSCs, which can be classified as TTX-sensitive or TTX-resistant channels according to their sensitivity to this toxin. Alterations in the expression and/or function of some specific TTX-sensitive VGSCs have been implicated in a number of chronic pain conditions. The administration of TTX at doses below those that interfere with the generation and conduction of action potentials in normal (non-injured) nerves has been used in humans and experimental animals under different pain conditions. These data indicate a role for TTX as a potential therapeutic agent for pain. This review focuses on the preclinical and clinical evidence supporting a potential analgesic role for TTX. In addition, the contribution of specific TTX-sensitive VGSCs to pain is reviewed.
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