1
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Wang H, Lu Y. High calcium concentrations reduce cellular excitability of mouse MNTB neurons. Brain Res 2023; 1820:148568. [PMID: 37689332 PMCID: PMC10591835 DOI: 10.1016/j.brainres.2023.148568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 09/04/2023] [Accepted: 09/06/2023] [Indexed: 09/11/2023]
Abstract
Calcium, a universal intracellular signaling molecule, plays essential roles in neural functions. Historically, in most in vitro brain slice electrophysiology studies, the extracellular calcium concentration ([Ca2+]e) in artificial cerebrospinal fluid is of a wide range and typically higher than the physiological value. At high [Ca2+]e, synaptic transmission is generally enhanced. However, the effects and the underlying mechanisms of calcium on intrinsic neuronal properties are diverse. Using whole-cell patch clamp in acute brainstem slices obtained from mice of either sex, we investigated the effects and the underlying mechanisms of high [Ca2+]e on intrinsic neuronal properties of neurons in the medial nucleus of the trapezoid body (MNTB), an auditory brainstem component in the sound localization circuitry. Compared to the physiological [Ca2+]e (1.2 mM), high [Ca2+]e at 1.8 and 2.4 mM significantly reduced the cellular excitability of MNTB neurons, resulting in decreased spike firing rate, depolarized spike threshold, and decreased the ability to follow high frequency inputs. High extracellular magnesium concentrations at 1.8 and 2.4 mM produced similar but less robust effects, due to surface charge screening. Upon high calcium application, voltage-gated sodium channel currents remained largely unchanged. Calcium-sensing receptors were detected in MNTB neurons, but blocking these receptors did not eliminate the effects of high calcium on spontaneous spiking. We attribute the lack of significant effects in these last two experiments to the moderate changes in calcium we tested. Our results call for the use of physiological [Ca2+]e in brain slice experiments.
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Affiliation(s)
- Huimei Wang
- Department of Anatomy and Neurobiology, Hearing Research Group, College of Medicine, Northeast Ohio Medical University, Rootstown, OH 44272, USA
| | - Yong Lu
- Department of Anatomy and Neurobiology, Hearing Research Group, College of Medicine, Northeast Ohio Medical University, Rootstown, OH 44272, USA.
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2
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Selimi Z, Rougier JS, Abriel H, Kucera JP. A detailed analysis of single-channel Na v 1.5 recordings does not reveal any cooperative gating. J Physiol 2023; 601:3847-3868. [PMID: 37470338 DOI: 10.1113/jp284861] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 06/23/2023] [Indexed: 07/21/2023] Open
Abstract
Cardiac voltage-gated sodium (Na+ ) channels (Nav 1.5) are crucial for myocardial electrical excitation. Recent studies based on single-channel recordings have suggested that Na+ channels interact functionally and exhibit coupled gating. However, the analysis of such recordings frequently relies on manual interventions, which can lead to bias. Here, we developed an automated pipeline to de-trend and idealize single-channel currents, and assessed possible functional interactions in cell-attached patch clamp experiments in HEK293 cells expressing human Nav 1.5 channels as well as in adult mouse and rabbit ventricular cardiomyocytes. Our pipeline involved de-trending individual sweeps by linear optimization using a library of predefined functions, followed by digital filtering and baseline offset. Subsequently, the processed sweeps were idealized based on the idea that the ensemble average of the idealized current identified by thresholds between current levels reconstructs at best the ensemble average current from the de-trended sweeps. This reconstruction was achieved by non-linear optimization. To ascertain functional interactions, we examined the distribution of the numbers of open channels at every time point during the activation protocol and compared it to the distribution expected for independent channels. We also examined whether the channels tended to synchronize their openings and closings. However, we did not uncover any solid evidence of such interactions in our recordings. Rather, our results indicate that wild-type Nav 1.5 channels are independent entities or exhibit only very weak functional interactions that are probably irrelevant under physiological conditions. Nevertheless, our unbiased analysis will be important for further studies examining whether auxiliary proteins potentiate functional Na+ channel interactions. KEY POINTS: Nav 1.5 channels are critical for cardiac excitation. They are part of macromolecular interacting complexes, and it was previously suggested that two neighbouring channels may functionally interact and exhibit coupled gating. Manual interventions when processing single-channel recordings can lead to bias and inaccurate data interpretation. We developed an automated pipeline to de-trend and idealize single-channel currents and assessed possible functional interactions between Nav 1.5 channels in HEK293 cells and cardiomyocytes during activation protocols using the cell-attached patch clamp technique. In recordings consisting of up to 1000 sweeps from the same patch, our analysis did not reveal any evidence of functional interactions or coupled gating between wild-type Nav 1.5 channels. Our unbiased analysis may be useful in further studies examining how Na+ channel interactions are affected by mutations and auxiliary proteins.
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Affiliation(s)
- Zoja Selimi
- Department of Physiology, University of Bern, Bern, Switzerland
| | | | - Hugues Abriel
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland
| | - Jan P Kucera
- Department of Physiology, University of Bern, Bern, Switzerland
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3
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Calmodulin variant E140G associated with long QT syndrome impairs CaMKIIδ autophosphorylation and L-type calcium channel inactivation. J Biol Chem 2023; 299:102777. [PMID: 36496072 PMCID: PMC9830374 DOI: 10.1016/j.jbc.2022.102777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 11/29/2022] [Accepted: 12/01/2022] [Indexed: 12/13/2022] Open
Abstract
Long QT syndrome (LQTS) is a human inherited heart condition that can cause life-threatening arrhythmia including sudden cardiac death. Mutations in the ubiquitous Ca2+-sensing protein calmodulin (CaM) are associated with LQTS, but the molecular mechanism by which these mutations lead to irregular heartbeats is not fully understood. Here, we use a multidisciplinary approach including protein biophysics, structural biology, confocal imaging, and patch-clamp electrophysiology to determine the effect of the disease-associated CaM mutation E140G on CaM structure and function. We present novel data showing that mutant-regulated CaMKIIδ kinase activity is impaired with a significant reduction in enzyme autophosphorylation rate. We report the first high-resolution crystal structure of a LQTS-associated CaM variant in complex with the CaMKIIδ peptide, which shows significant structural differences, compared to the WT complex. Furthermore, we demonstrate that the E140G mutation significantly disrupted Cav1.2 Ca2+/CaM-dependent inactivation, while cardiac ryanodine receptor (RyR2) activity remained unaffected. In addition, we show that the LQTS-associated mutation alters CaM's Ca2+-binding characteristics, secondary structure content, and interaction with key partners involved in excitation-contraction coupling (CaMKIIδ, Cav1.2, RyR2). In conclusion, LQTS-associated CaM mutation E140G severely impacts the structure-function relationship of CaM and its regulation of CaMKIIδ and Cav1.2. This provides a crucial insight into the molecular factors contributing to CaM-mediated arrhythmias with a central role for CaMKIIδ.
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4
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Echevarria-Cooper DM, Hawkins NA, Misra SN, Huffman AM, Thaxton T, Thompson CH, Ben-Shalom R, Nelson AD, Lipkin AM, George AL, Bender KJ, Kearney JA. Cellular and behavioral effects of altered NaV1.2 sodium channel ion permeability in Scn2aK1422E mice. Hum Mol Genet 2022; 31:2964-2988. [PMID: 35417922 PMCID: PMC9433730 DOI: 10.1093/hmg/ddac087] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 03/28/2022] [Accepted: 04/09/2022] [Indexed: 11/13/2022] Open
Abstract
Genetic variants in SCN2A, encoding the NaV1.2 voltage-gated sodium channel, are associated with a range of neurodevelopmental disorders with overlapping phenotypes. Some variants fit into a framework wherein gain-of-function missense variants that increase neuronal excitability lead to developmental and epileptic encephalopathy, while loss-of-function variants that reduce neuronal excitability lead to intellectual disability and/or autism spectrum disorder (ASD) with or without co-morbid seizures. One unique case less easily classified using this framework is the de novo missense variant SCN2A-p.K1422E, associated with infant-onset developmental delay, infantile spasms and features of ASD. Prior structure–function studies demonstrated that K1422E substitution alters ion selectivity of NaV1.2, conferring Ca2+ permeability, lowering overall conductance and conferring resistance to tetrodotoxin (TTX). Based on heterologous expression of K1422E, we developed a compartmental neuron model incorporating variant channels that predicted reductions in peak action potential (AP) speed. We generated Scn2aK1422E mice and characterized effects on neurons and neurological/neurobehavioral phenotypes. Cultured cortical neurons from heterozygous Scn2aK1422E/+ mice exhibited lower current density with a TTX-resistant component and reversal potential consistent with mixed ion permeation. Recordings from Scn2aK1442E/+ cortical slices demonstrated impaired AP initiation and larger Ca2+ transients at the axon initial segment during the rising phase of the AP, suggesting complex effects on channel function. Scn2aK1422E/+ mice exhibited rare spontaneous seizures, interictal electroencephalogram abnormalities, altered induced seizure thresholds, reduced anxiety-like behavior and alterations in olfactory-guided social behavior. Overall, Scn2aK1422E/+ mice present with phenotypes similar yet distinct from other Scn2a models, consistent with complex effects of K1422E on NaV1.2 channel function.
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Affiliation(s)
- Dennis M Echevarria-Cooper
- Departments of Pharmacology, Northwestern University Feinberg School of Medicine; Chicago, IL, USA 60611.,Northwestern University Interdepartmental Neuroscience Program, Northwestern University, Chicago, IL, USA, 60611
| | - Nicole A Hawkins
- Departments of Pharmacology, Northwestern University Feinberg School of Medicine; Chicago, IL, USA 60611
| | - Sunita N Misra
- Departments of Pharmacology, Northwestern University Feinberg School of Medicine; Chicago, IL, USA 60611.,Departments of Pediatrics, Northwestern University Feinberg School of Medicine; Chicago, IL, USA 60611.,Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA 60611
| | - Alexandra M Huffman
- Departments of Pharmacology, Northwestern University Feinberg School of Medicine; Chicago, IL, USA 60611
| | - Tyler Thaxton
- Departments of Pharmacology, Northwestern University Feinberg School of Medicine; Chicago, IL, USA 60611
| | - Christopher H Thompson
- Departments of Pharmacology, Northwestern University Feinberg School of Medicine; Chicago, IL, USA 60611
| | - Roy Ben-Shalom
- Mind Institute and Department of Neurology, University of California, Davis, Sacramento, CA, United States 95817
| | - Andrew D Nelson
- Department of Neurology, Kavli Institute for Fundamental Neuroscience, Weill Institute for Neurosciences, University of California, San Francisco, CA, USA 94158
| | - Anna M Lipkin
- Department of Neurology, Kavli Institute for Fundamental Neuroscience, Weill Institute for Neurosciences, University of California, San Francisco, CA, USA 94158.,Neuroscience Graduate Program, University of California, San Francisco, CA, USA 94158
| | - Alfred L George
- Departments of Pharmacology, Northwestern University Feinberg School of Medicine; Chicago, IL, USA 60611.,Northwestern University Interdepartmental Neuroscience Program, Northwestern University, Chicago, IL, USA, 60611
| | - Kevin J Bender
- Department of Neurology, Kavli Institute for Fundamental Neuroscience, Weill Institute for Neurosciences, University of California, San Francisco, CA, USA 94158
| | - Jennifer A Kearney
- Departments of Pharmacology, Northwestern University Feinberg School of Medicine; Chicago, IL, USA 60611.,Northwestern University Interdepartmental Neuroscience Program, Northwestern University, Chicago, IL, USA, 60611
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5
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Kato K, Isbell HM, Fressart V, Denjoy I, Debbiche A, Itoh H, Poinsot J, George AL, Coulombe A, Shea MA, Guicheney P. Novel CALM3 Variant Causing Calmodulinopathy With Variable Expressivity in a 4-Generation Family. Circ Arrhythm Electrophysiol 2022; 15:e010572. [PMID: 35225649 DOI: 10.1161/circep.121.010572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND CaM (calmodulin), encoded by 3 separate genes (CALM1, CALM2, and CALM3), is a multifunctional Ca2+-binding protein involved in many signal transduction events including ion channel regulation. CaM variants may present with early-onset long QT syndrome (LQTS), catecholaminergic polymorphic ventricular tachycardia, or sudden cardiac death. Most reported variants occurred de novo. We identified a novel CALM3 variant, p.Asn138Lys (N138K), in a 4-generation family segregating with LQTS. The aim of this study was to elucidate its pathogenicity and to compare it with that of p.D130G-CaM-a variant associated with a severe LQTS phenotype. METHODS We performed whole exome sequencing for a large, 4-generation family affected by LQTS. To assess the effect of the detected CALM3 variant, the intrinsic Ca2+-binding affinity was measured by stoichiometric Ca2+ titrations and equilibrium titrations. L-type Ca2+ and slow delayed rectifier potassium currents (ICaL and IKs) were recorded by whole-cell patch-clamp. Cav1.2 and Kv7.1 membrane expression were determined by optical fluorescence assays. RESULTS We identified 14 p.N138K-CaM carriers in a family where 2 sudden deaths occurred in children. Several members were only mildly affected compared with CaM-LQTS patients to date described in literature. The intrinsic Ca2+-binding affinity of the CaM C-terminal domain was 10-fold lower for p.N138K-CaM compared with wild-type-CaM. ICaL inactivation was slowed in cells expressing p.N138K-CaM but less than in p.D130G-CaM cells. Unexpectedly, a larger IKs current density was observed in cells expressing p.N138K-CaM, but not for p.D130G-CaM, compared with wild-type-CaM. CONCLUSIONS The p.N138K CALM3 variant impairs Ca2+-binding affinity of CaM and ICaL inactivation but potentiates IKs. The variably expressed phenotype of this variant compared with previously published de novo LQTS-CaM variants is likely explained by a milder impairment of ICaL inactivation combined with IKs augmentation.
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Affiliation(s)
- Koichi Kato
- Sorbonne Université, Inserm, Research Unit on Cardiovascular and Metabolic Diseases, UMRS-1166, Paris, France (K.K., V.F., I.D., A.D., A.C., P.G.).,Department of Cardiovascular Medicine, Shiga University of Medical Science, Otsu, Japan (K.K.)
| | - Holly M Isbell
- Department of Biochemistry, Carver College of Medicine, University of Iowa (H.M.I., M.A.S.)
| | - Véronique Fressart
- AP-HP, Pitié-Salpêtrière Hospital, Functional Unit of Cardiogenetics and Myogenetics, Paris, France (V.F.)
| | - Isabelle Denjoy
- Sorbonne Université, Inserm, Research Unit on Cardiovascular and Metabolic Diseases, UMRS-1166, Paris, France (K.K., V.F., I.D., A.D., A.C., P.G.).,Cardiology Department, Referring Center for Heritable or Rare Cardiac Diseases, AP-HP, Bichat Hospital, HUPNVS, Referring Center for Rare Cardiac Diseases, Sorbonne University, Paris, France (I.D.)
| | - Amal Debbiche
- Sorbonne Université, Inserm, Research Unit on Cardiovascular and Metabolic Diseases, UMRS-1166, Paris, France (K.K., V.F., I.D., A.D., A.C., P.G.)
| | - Hideki Itoh
- Division of Patient Safety, Hiroshima University Hospital, Japan (H.I.)
| | - Jacques Poinsot
- Unité de cardio-pediatrie, service de medecine pediatrique, Centre Hospitalier Universitaire de Tours, Tours, France (J.P.)
| | - Alfred L George
- Department of Pharmacology Northwestern University Feinberg School of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL (A.L.G.)
| | - Alain Coulombe
- Sorbonne Université, Inserm, Research Unit on Cardiovascular and Metabolic Diseases, UMRS-1166, Paris, France (K.K., V.F., I.D., A.D., A.C., P.G.)
| | - Madeline A Shea
- Department of Biochemistry, Carver College of Medicine, University of Iowa (H.M.I., M.A.S.)
| | - Pascale Guicheney
- Sorbonne Université, Inserm, Research Unit on Cardiovascular and Metabolic Diseases, UMRS-1166, Paris, France (K.K., V.F., I.D., A.D., A.C., P.G.)
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6
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Horváth B, Szentandrássy N, Almássy J, Dienes C, Kovács ZM, Nánási PP, Banyasz T. Late Sodium Current of the Heart: Where Do We Stand and Where Are We Going? Pharmaceuticals (Basel) 2022; 15:ph15020231. [PMID: 35215342 PMCID: PMC8879921 DOI: 10.3390/ph15020231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 02/07/2022] [Accepted: 02/09/2022] [Indexed: 02/05/2023] Open
Abstract
Late sodium current has long been linked to dysrhythmia and contractile malfunction in the heart. Despite the increasing body of accumulating information on the subject, our understanding of its role in normal or pathologic states is not complete. Even though the role of late sodium current in shaping action potential under physiologic circumstances is debated, it’s unquestioned role in arrhythmogenesis keeps it in the focus of research. Transgenic mouse models and isoform-specific pharmacological tools have proved useful in understanding the mechanism of late sodium current in health and disease. This review will outline the mechanism and function of cardiac late sodium current with special focus on the recent advances of the area.
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Affiliation(s)
- Balázs Horváth
- Department of Physiology, University of Debrecen, 4032 Debrecen, Hungary; (B.H.); (N.S.); (J.A.); (C.D.); (Z.M.K.); (P.P.N.)
| | - Norbert Szentandrássy
- Department of Physiology, University of Debrecen, 4032 Debrecen, Hungary; (B.H.); (N.S.); (J.A.); (C.D.); (Z.M.K.); (P.P.N.)
- Department of Basic Medical Sciences, Faculty of Dentistry, University of Debrecen, 4032 Debrecen, Hungary
| | - János Almássy
- Department of Physiology, University of Debrecen, 4032 Debrecen, Hungary; (B.H.); (N.S.); (J.A.); (C.D.); (Z.M.K.); (P.P.N.)
| | - Csaba Dienes
- Department of Physiology, University of Debrecen, 4032 Debrecen, Hungary; (B.H.); (N.S.); (J.A.); (C.D.); (Z.M.K.); (P.P.N.)
| | - Zsigmond Máté Kovács
- Department of Physiology, University of Debrecen, 4032 Debrecen, Hungary; (B.H.); (N.S.); (J.A.); (C.D.); (Z.M.K.); (P.P.N.)
| | - Péter P. Nánási
- Department of Physiology, University of Debrecen, 4032 Debrecen, Hungary; (B.H.); (N.S.); (J.A.); (C.D.); (Z.M.K.); (P.P.N.)
- Department of Dental Physiology and Pharmacology, University of Debrecen, 4032 Debrecen, Hungary
| | - Tamas Banyasz
- Department of Physiology, University of Debrecen, 4032 Debrecen, Hungary; (B.H.); (N.S.); (J.A.); (C.D.); (Z.M.K.); (P.P.N.)
- Correspondence: ; Tel.: +36-(52)-255-575; Fax: +36-(52)-255-116
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7
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Ishida H, Vogel HJ, Conner AC, Kitchen P, Bill RM, MacDonald JA. Simultaneous binding of the N- and C-terminal cytoplasmic domains of aquaporin 4 to calmodulin. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183837. [PMID: 34890582 DOI: 10.1016/j.bbamem.2021.183837] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 10/30/2021] [Accepted: 11/30/2021] [Indexed: 10/19/2022]
Abstract
Aquaporin 4 (AQP4) is a water transporting, transmembrane channel protein that has important regulatory roles in maintaining cellular water homeostasis. Several other AQP proteins exhibit calmodulin (CaM)-binding properties, and CaM has recently been implicated in the cell surface localization of AQP4. The objective of the present study was to assess the CaM-binding properties of AQP4 in detail. Inspection of AQP4 revealed two putative CaM-binding domains (CBDs) in the cytoplasmic N- and C-terminal regions, respectively. The Ca2+-dependent CaM-binding properties of AQP4 CBD peptides were assessed using fluorescence spectroscopy, isothermal titration calorimetry, and two-dimensional 1H, 15N-HSQC NMR with 15N-labeled CaM. The N-terminal CBD of AQP4 predominantly interacted with the N-lobe of CaM with a 1:1 binding ratio and a Kd of 3.4 μM. The C-terminal AQP4 peptide interacted with both the C- and N-lobes of CaM (2:1 binding ratio; Kd1: 3.6 μM, Kd2: 113.6 μM, respectively). A recombinant AQP4 protein domain (recAQP4CT, containing the entire cytosolic C-terminal sequence) bound CaM in a 1:1 binding mode with a Kd of 6.1 μM. A ternary bridging complex could be generated with the N- and C-lobes of CaM interacting simultaneously with the N- and C-terminal CBD peptides. These data support a unique adapter protein binding mode for CaM with AQP4.
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Affiliation(s)
- Hiroaki Ishida
- Biochemistry Research Group, Department of Biological Sciences, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Hans J Vogel
- Biochemistry Research Group, Department of Biological Sciences, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Alex C Conner
- College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Philip Kitchen
- College of Health and Life Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK
| | - Roslyn M Bill
- College of Health and Life Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK
| | - Justin A MacDonald
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4Z6, Canada.
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Kistamás K, Hézső T, Horváth B, Nánási PP. Late sodium current and calcium homeostasis in arrhythmogenesis. Channels (Austin) 2021; 15:1-19. [PMID: 33258400 PMCID: PMC7757849 DOI: 10.1080/19336950.2020.1854986] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 10/26/2020] [Accepted: 11/19/2020] [Indexed: 12/19/2022] Open
Abstract
The cardiac late sodium current (INa,late) is the small sustained component of the sodium current active during the plateau phase of the action potential. Several studies demonstrated that augmentation of the current can lead to cardiac arrhythmias; therefore, INa,late is considered as a promising antiarrhythmic target. Fundamentally, enlarged INa,late increases Na+ influx into the cell, which, in turn, is converted to elevated intracellular Ca2+ concentration through the Na+/Ca2+ exchanger. The excessive Ca2+ load is known to be proarrhythmic. This review describes the behavior of the voltage-gated Na+ channels generating INa,late in health and disease and aims to discuss the physiology and pathophysiology of Na+ and Ca2+ homeostasis in context with the enhanced INa,late demonstrating also the currently accessible antiarrhythmic choices.
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Affiliation(s)
- Kornél Kistamás
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Tamás Hézső
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Balázs Horváth
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Péter P Nánási
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Department of Dental Physiology, Faculty of Dentistry, University of Debrecen, Debrecen, Hungary
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9
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Kiss D, Horváth B, Hézső T, Dienes C, Kovács Z, Topal L, Szentandrássy N, Almássy J, Prorok J, Virág L, Bányász T, Varró A, Nánási PP, Magyar J. Late Na + Current Is [Ca 2+] i-Dependent in Canine Ventricular Myocytes. Pharmaceuticals (Basel) 2021; 14:ph14111142. [PMID: 34832924 PMCID: PMC8623624 DOI: 10.3390/ph14111142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 10/27/2021] [Accepted: 11/02/2021] [Indexed: 11/16/2022] Open
Abstract
Enhancement of the late sodium current (INaL) increases arrhythmia propensity in the heart, whereas suppression of the current is antiarrhythmic. In the present study, we investigated INaL in canine ventricular cardiomyocytes under action potential voltage-clamp conditions using the selective Na+ channel inhibitors GS967 and tetrodotoxin. Both 1 µM GS967 and 10 µM tetrodotoxin dissected largely similar inward currents. The amplitude and integral of the GS967-sensitive current was significantly smaller after the reduction of intracellular Ca2+ concentration ([Ca2+]i) either by superfusion of the cells with 1 µM nisoldipine or by intracellular application of 10 mM BAPTA. Inhibiting calcium/calmodulin-dependent protein kinase II (CaMKII) by KN-93 or the autocamtide-2-related inhibitor peptide similarly reduced the amplitude and integral of INaL. Action potential duration was shortened in a reverse rate-dependent manner and the plateau potential was depressed by GS967. This GS967-induced depression of plateau was reduced by pretreatment of the cells with BAPTA-AM. We conclude that (1) INaL depends on the magnitude of [Ca2+]i in canine ventricular cells, (2) this [Ca2+]i-dependence of INaL is mediated by the Ca2+-dependent activation of CaMKII, and (3) INaL is augmented by the baseline CaMKII activity.
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Affiliation(s)
- Dénes Kiss
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (D.K.); (B.H.); (T.H.); (C.D.); (Z.K.); (N.S.); (J.A.); (T.B.); (J.M.)
| | - Balázs Horváth
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (D.K.); (B.H.); (T.H.); (C.D.); (Z.K.); (N.S.); (J.A.); (T.B.); (J.M.)
- Faculty of Pharmacy, University of Debrecen, 4032 Debrecen, Hungary
| | - Tamás Hézső
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (D.K.); (B.H.); (T.H.); (C.D.); (Z.K.); (N.S.); (J.A.); (T.B.); (J.M.)
| | - Csaba Dienes
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (D.K.); (B.H.); (T.H.); (C.D.); (Z.K.); (N.S.); (J.A.); (T.B.); (J.M.)
| | - Zsigmond Kovács
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (D.K.); (B.H.); (T.H.); (C.D.); (Z.K.); (N.S.); (J.A.); (T.B.); (J.M.)
| | - Leila Topal
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, 6725 Szeged, Hungary; (L.T.); (J.P.); (L.V.); (A.V.)
| | - Norbert Szentandrássy
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (D.K.); (B.H.); (T.H.); (C.D.); (Z.K.); (N.S.); (J.A.); (T.B.); (J.M.)
- Department of Basic Medical Sciences, Faculty of Dentistry, University of Debrecen, 4032 Debrecen, Hungary
| | - János Almássy
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (D.K.); (B.H.); (T.H.); (C.D.); (Z.K.); (N.S.); (J.A.); (T.B.); (J.M.)
| | - János Prorok
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, 6725 Szeged, Hungary; (L.T.); (J.P.); (L.V.); (A.V.)
- ELKH-SZTE Research Group for Cardiovascular Pharmacology, Eötvös Loránd Research Network, 6725 Szeged, Hungary
| | - László Virág
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, 6725 Szeged, Hungary; (L.T.); (J.P.); (L.V.); (A.V.)
- Department of Pharmacology and Pharmacotherapy, Interdisciplinary Excellence Centre, University of Szeged, 6725 Szeged, Hungary
| | - Tamás Bányász
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (D.K.); (B.H.); (T.H.); (C.D.); (Z.K.); (N.S.); (J.A.); (T.B.); (J.M.)
| | - András Varró
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, 6725 Szeged, Hungary; (L.T.); (J.P.); (L.V.); (A.V.)
- ELKH-SZTE Research Group for Cardiovascular Pharmacology, Eötvös Loránd Research Network, 6725 Szeged, Hungary
- Department of Pharmacology and Pharmacotherapy, Interdisciplinary Excellence Centre, University of Szeged, 6725 Szeged, Hungary
| | - Péter P. Nánási
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (D.K.); (B.H.); (T.H.); (C.D.); (Z.K.); (N.S.); (J.A.); (T.B.); (J.M.)
- Department of Dental Physiology and Pharmacology, Faculty of Dentistry, University of Debrecen, 4032 Debrecen, Hungary
- Correspondence: ; Tel.: +36-52255575; Fax: +36-52255116
| | - János Magyar
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (D.K.); (B.H.); (T.H.); (C.D.); (Z.K.); (N.S.); (J.A.); (T.B.); (J.M.)
- Division of Sport Physiology, Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
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10
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Ca2+-dependent modulation of voltage-gated myocyte sodium channels. Biochem Soc Trans 2021; 49:1941-1961. [PMID: 34643236 PMCID: PMC8589445 DOI: 10.1042/bst20200604] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 08/01/2021] [Accepted: 08/31/2021] [Indexed: 12/19/2022]
Abstract
Voltage-dependent Na+ channel activation underlies action potential generation fundamental to cellular excitability. In skeletal and cardiac muscle this triggers contraction via ryanodine-receptor (RyR)-mediated sarcoplasmic reticular (SR) Ca2+ release. We here review potential feedback actions of intracellular [Ca2+] ([Ca2+]i) on Na+ channel activity, surveying their structural, genetic and cellular and functional implications, translating these to their possible clinical importance. In addition to phosphorylation sites, both Nav1.4 and Nav1.5 possess potentially regulatory binding sites for Ca2+ and/or the Ca2+-sensor calmodulin in their inactivating III–IV linker and C-terminal domains (CTD), where mutations are associated with a range of skeletal and cardiac muscle diseases. We summarize in vitro cell-attached patch clamp studies reporting correspondingly diverse, direct and indirect, Ca2+ effects upon maximal Nav1.4 and Nav1.5 currents (Imax) and their half-maximal voltages (V1/2) characterizing channel gating, in cellular expression systems and isolated myocytes. Interventions increasing cytoplasmic [Ca2+]i down-regulated Imax leaving V1/2 constant in native loose patch clamped, wild-type murine skeletal and cardiac myocytes. They correspondingly reduced action potential upstroke rates and conduction velocities, causing pro-arrhythmic effects in intact perfused hearts. Genetically modified murine RyR2-P2328S hearts modelling catecholaminergic polymorphic ventricular tachycardia (CPVT), recapitulated clinical ventricular and atrial pro-arrhythmic phenotypes following catecholaminergic challenge. These accompanied reductions in action potential conduction velocities. The latter were reversed by flecainide at RyR-blocking concentrations specifically in RyR2-P2328S as opposed to wild-type hearts, suggesting a basis for its recent therapeutic application in CPVT. We finally explore the relevance of these mechanisms in further genetic paradigms for commoner metabolic and structural cardiac disease.
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11
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Wu X, Hong L. Calmodulin Interactions with Voltage-Gated Sodium Channels. Int J Mol Sci 2021; 22:ijms22189798. [PMID: 34575961 PMCID: PMC8472079 DOI: 10.3390/ijms22189798] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Revised: 09/06/2021] [Accepted: 09/07/2021] [Indexed: 02/06/2023] Open
Abstract
Calmodulin (CaM) is a small protein that acts as a ubiquitous signal transducer and regulates neuronal plasticity, muscle contraction, and immune response. It interacts with ion channels and plays regulatory roles in cellular electrophysiology. CaM modulates the voltage-gated sodium channel gating process, alters sodium current density, and regulates sodium channel protein trafficking and expression. Many mutations in the CaM-binding IQ domain give rise to diseases including epilepsy, autism, and arrhythmias by interfering with CaM interaction with the channel. In the present review, we discuss CaM interactions with the voltage-gated sodium channel and modulators involved in CaM regulation, as well as summarize CaM-binding IQ domain mutations associated with human diseases in the voltage-gated sodium channel family.
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12
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Comparative structural analysis of human Na v1.1 and Na v1.5 reveals mutational hotspots for sodium channelopathies. Proc Natl Acad Sci U S A 2021; 118:2100066118. [PMID: 33712547 DOI: 10.1073/pnas.2100066118] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Among the nine subtypes of human voltage-gated sodium (Nav) channels, the brain and cardiac isoforms, Nav1.1 and Nav1.5, each carry more than 400 missense mutations respectively associated with epilepsy and cardiac disorders. High-resolution structures are required for structure-function relationship dissection of the disease variants. We report the cryo-EM structures of the full-length human Nav1.1-β4 complex at 3.3 Å resolution here and the Nav1.5-E1784K variant in the accompanying paper. Up to 341 and 261 disease-related missense mutations in Nav1.1 and Nav1.5, respectively, are resolved. Comparative structural analysis reveals several clusters of disease mutations that are common to both Nav1.1 and Nav1.5. Among these, the majority of mutations on the extracellular loops above the pore domain and the supporting segments for the selectivity filter may impair structural integrity, while those on the pore domain and the voltage-sensing domains mostly interfere with electromechanical coupling and fast inactivation. Our systematic structural delineation of these mutations provides important insight into their pathogenic mechanism, which will facilitate the development of precise therapeutic interventions against various sodium channelopathies.
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13
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Kushner J, Papa A, Marx SO. Use of Proximity Labeling in Cardiovascular Research. JACC Basic Transl Sci 2021; 6:598-609. [PMID: 34368510 PMCID: PMC8326230 DOI: 10.1016/j.jacbts.2021.01.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 12/11/2020] [Accepted: 01/06/2021] [Indexed: 10/31/2022]
Abstract
Protein-protein interactions are of paramount importance in regulating normal cardiac physiology. Methodologies to elucidate these interactions in vivo have been limited. Recently, proximity-dependent biotinylation, with the use of BioID, TurboID, and ascorbate peroxidase, has been developed to uncover cellular neighborhoods and novel protein-protein interactions. These cutting-edge techniques have enabled the identification of subcellular localizations of specific proteins and the neighbors or interacting proteins within these subcellular regions. In contrast to classic methods such as affinity purification and subcellular fractionation, these techniques add covalently bound tags in living cells, such that spatial relationships and interaction networks are not disrupted. Recently, these methodologies have been used to identify novel protein-protein interactions relevant to the cardiovascular system. In this review, we discuss the development and current use of proximity biotin-labeling for cardiovascular research.
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Affiliation(s)
- Jared Kushner
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, New York, USA
| | - Arianne Papa
- Department of Physiology and Cellular Biophysics, Columbia University, Vagelos College of Physicians and Surgeons, New York, New York, USA
| | - Steven O. Marx
- Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, New York, USA
- Department of Molecular Pharmacology and Therapeutics, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York, USA
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14
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Zybura A, Hudmon A, Cummins TR. Distinctive Properties and Powerful Neuromodulation of Na v1.6 Sodium Channels Regulates Neuronal Excitability. Cells 2021; 10:cells10071595. [PMID: 34202119 PMCID: PMC8307729 DOI: 10.3390/cells10071595] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 06/20/2021] [Accepted: 06/21/2021] [Indexed: 12/19/2022] Open
Abstract
Voltage-gated sodium channels (Navs) are critical determinants of cellular excitability. These ion channels exist as large heteromultimeric structures and their activity is tightly controlled. In neurons, the isoform Nav1.6 is highly enriched at the axon initial segment and nodes, making it critical for the initiation and propagation of neuronal impulses. Changes in Nav1.6 expression and function profoundly impact the input-output properties of neurons in normal and pathological conditions. While mutations in Nav1.6 may cause channel dysfunction, aberrant changes may also be the result of complex modes of regulation, including various protein-protein interactions and post-translational modifications, which can alter membrane excitability and neuronal firing properties. Despite decades of research, the complexities of Nav1.6 modulation in health and disease are still being determined. While some modulatory mechanisms have similar effects on other Nav isoforms, others are isoform-specific. Additionally, considerable progress has been made toward understanding how individual protein interactions and/or modifications affect Nav1.6 function. However, there is still more to be learned about how these different modes of modulation interact. Here, we examine the role of Nav1.6 in neuronal function and provide a thorough review of this channel’s complex regulatory mechanisms and how they may contribute to neuromodulation.
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Affiliation(s)
- Agnes Zybura
- Program in Medical Neuroscience, Paul and Carole Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA;
- Biology Department, School of Science, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA
| | - Andy Hudmon
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA;
| | - Theodore R. Cummins
- Program in Medical Neuroscience, Paul and Carole Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA;
- Biology Department, School of Science, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA
- Correspondence:
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15
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Abstract
By evaluating children with a malformed cerebral cortex, we identified an ATPase pump (ATP1A3) with an early role in brain development. The ATP1A3 pump maintains the physiological concentration of sodium and potassium ions in cells, a process critical for osmotic equilibrium and membrane potential across several developing cell populations. We employed single-cell sequencing approaches to identify key enrichments for ATP1A3 expression during human cortex development. Unravelling this early cell-type–specific pathophysiology in the developing brain offers a potential basis for the treatment of ATP1A3-related diseases affecting prenatal and early childhood development. Osmotic equilibrium and membrane potential in animal cells depend on concentration gradients of sodium (Na+) and potassium (K+) ions across the plasma membrane, a function catalyzed by the Na+,K+-ATPase α-subunit. Here, we describe ATP1A3 variants encoding dysfunctional α3-subunits in children affected by polymicrogyria, a developmental malformation of the cerebral cortex characterized by abnormal folding and laminar organization. To gain cell-biological insights into the spatiotemporal dynamics of prenatal ATP1A3 expression, we built an ATP1A3 transcriptional atlas of fetal cortical development using mRNA in situ hybridization and transcriptomic profiling of ∼125,000 individual cells with single-cell RNA sequencing (Drop-seq) from 11 areas of the midgestational human neocortex. We found that fetal expression of ATP1A3 is most abundant to a subset of excitatory neurons carrying transcriptional signatures of the developing subplate, yet also maintains expression in nonneuronal cell populations. Moving forward a year in human development, we profiled ∼52,000 nuclei from four areas of an infant neocortex and show that ATP1A3 expression persists throughout early postnatal development, most predominantly in inhibitory neurons, including parvalbumin interneurons in the frontal cortex. Finally, we discovered the heteromeric Na+,K+-ATPase pump complex may form nonredundant cell-type–specific α-β isoform combinations, including α3-β1 in excitatory neurons and α3-β2 in inhibitory neurons. Together, the developmental malformation phenotype of affected individuals and single-cell ATP1A3 expression patterns point to a key role for α3 in human cortex development, as well as a cell-type basis for pre- and postnatal ATP1A3-associated diseases.
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16
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Kang PW, Chakouri N, Diaz J, Tomaselli GF, Yue DT, Ben-Johny M. Elementary mechanisms of calmodulin regulation of Na V1.5 producing divergent arrhythmogenic phenotypes. Proc Natl Acad Sci U S A 2021; 118:e2025085118. [PMID: 34021086 PMCID: PMC8166197 DOI: 10.1073/pnas.2025085118] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
In cardiomyocytes, NaV1.5 channels mediate initiation and fast propagation of action potentials. The Ca2+-binding protein calmodulin (CaM) serves as a de facto subunit of NaV1.5. Genetic studies and atomic structures suggest that this interaction is pathophysiologically critical, as human mutations within the NaV1.5 carboxy-terminus that disrupt CaM binding are linked to distinct forms of life-threatening arrhythmias, including long QT syndrome 3, a "gain-of-function" defect, and Brugada syndrome, a "loss-of-function" phenotype. Yet, how a common disruption in CaM binding engenders divergent effects on NaV1.5 gating is not fully understood, though vital for elucidating arrhythmogenic mechanisms and for developing new therapies. Here, using extensive single-channel analysis, we find that the disruption of Ca2+-free CaM preassociation with NaV1.5 exerts two disparate effects: 1) a decrease in the peak open probability and 2) an increase in persistent NaV openings. Mechanistically, these effects arise from a CaM-dependent switch in the NaV inactivation mechanism. Specifically, CaM-bound channels preferentially inactivate from the open state, while those devoid of CaM exhibit enhanced closed-state inactivation. Further enriching this scheme, for certain mutant NaV1.5, local Ca2+ fluctuations elicit a rapid recruitment of CaM that reverses the increase in persistent Na current, a factor that may promote beat-to-beat variability in late Na current. In all, these findings identify the elementary mechanism of CaM regulation of NaV1.5 and, in so doing, unravel a noncanonical role for CaM in tuning ion channel gating. Furthermore, our results furnish an in-depth molecular framework for understanding complex arrhythmogenic phenotypes of NaV1.5 channelopathies.
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Affiliation(s)
- Po Wei Kang
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21218;
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO 63130
| | - Nourdine Chakouri
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY 10032
| | - Johanna Diaz
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY 10032
| | - Gordon F Tomaselli
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY 10461
| | - David T Yue
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21218
| | - Manu Ben-Johny
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21218;
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY 10032
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17
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Lin QT, Lee R, Feng AL, Kim MS, Stathopulos PB. The leucine zipper EF-hand containing transmembrane protein-1 EF-hand is a tripartite calcium, temperature, and pH sensor. Protein Sci 2021; 30:855-872. [PMID: 33576522 DOI: 10.1002/pro.4042] [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] [Received: 12/28/2020] [Revised: 02/09/2021] [Accepted: 02/09/2021] [Indexed: 12/15/2022]
Abstract
Leucine Zipper EF-hand containing transmembrane protein-1 (LETM1) is an inner mitochondrial membrane protein that mediates mitochondrial calcium (Ca2+ )/proton exchange. The matrix residing carboxyl (C)-terminal domain contains a sequence identifiable EF-hand motif (EF1) that is highly conserved among orthologues. Deletion of EF1 abrogates LETM1 mediated mitochondrial Ca2+ flux, highlighting the requirement of EF1 for LETM1 function. To understand the mechanistic role of this EF-hand in LETM1 function, we characterized the biophysical properties of EF1 in isolation. Our data show that EF1 exhibits α-helical secondary structure that is augmented in the presence of Ca2+ . Unexpectedly, EF1 features a weak (~mM), but specific, apparent Ca2+ -binding affinity, consistent with the canonical Ca2+ coordination geometry, suggested by our solution NMR. The low affinity is, at least in part, due to an Asp at position 12 of the binding loop, where mutation to Glu increases the affinity by ~4-fold. Further, the binding affinity is sensitive to pH changes within the physiological range experienced by mitochondria. Remarkably, EF1 unfolds at high and low temperatures. Despite these unique EF-hand properties, Ca2+ binding increases the exposure of hydrophobic regions, typical of EF-hands; however, this Ca2+ -induced conformational change shifts EF1 from a monomer to higher order oligomers. Finally, we showed that a second, putative EF-hand within LETM1 is unreactive to Ca2+ either in isolation or tandem with EF1. Collectively, our data reveal that EF1 is structurally and biophysically responsive to pH, Ca2+ and temperature, suggesting a role as a multipartite environmental sensor within LETM1.
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Affiliation(s)
- Qi-Tong Lin
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
| | - Rachel Lee
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada.,Temerty Faculty of Medicine, University of Toronto, Toronto, Canada
| | - Allen L Feng
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada.,Faculty of Dentistry, University of Toronto, Toronto, Canada
| | - Michael S Kim
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada.,Department of Radiation Oncology, Dalhousie University, Halifax, Canada
| | - Peter B Stathopulos
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
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18
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Saadeh K, Fazmin IT. Mitochondrial Dysfunction Increases Arrhythmic Triggers and Substrates; Potential Anti-arrhythmic Pharmacological Targets. Front Cardiovasc Med 2021; 8:646932. [PMID: 33659284 PMCID: PMC7917191 DOI: 10.3389/fcvm.2021.646932] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Accepted: 01/26/2021] [Indexed: 12/31/2022] Open
Abstract
Incidence of cardiac arrhythmias increases significantly with age. In order to effectively stratify arrhythmic risk in the aging population it is crucial to elucidate the relevant underlying molecular mechanisms. The changes underlying age-related electrophysiological disruption appear to be closely associated with mitochondrial dysfunction. Thus, the present review examines the mechanisms by which age-related mitochondrial dysfunction promotes arrhythmic triggers and substrate. Namely, via alterations in plasmalemmal ionic currents (both sodium and potassium), gap junctions, cellular Ca2+ homeostasis, and cardiac fibrosis. Stratification of patients' mitochondrial function status permits application of appropriate anti-arrhythmic therapies. Here, we discuss novel potential anti-arrhythmic pharmacological interventions that specifically target upstream mitochondrial function and hence ameliorates the need for therapies targeting downstream changes which have constituted traditional antiarrhythmic therapy.
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Affiliation(s)
- Khalil Saadeh
- School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom.,Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Ibrahim Talal Fazmin
- School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom.,Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom.,Royal Papworth Hospital NHS Foundation Trust, Cambridge, United Kingdom
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19
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Abstract
Long QT syndrome (LQTS) is a cardiovascular disorder characterized by an abnormality in cardiac repolarization leading to a prolonged QT interval and T-wave irregularities on the surface electrocardiogram. It is commonly associated with syncope, seizures, susceptibility to torsades de pointes, and risk for sudden death. LQTS is a rare genetic disorder and a major preventable cause of sudden cardiac death in the young. The availability of therapy for this lethal disease emphasizes the importance of early and accurate diagnosis. Additionally, understanding of the molecular mechanisms underlying LQTS could help to optimize genotype-specific treatments to prevent deaths in LQTS patients. In this review, we briefly summarize current knowledge regarding molecular underpinning of LQTS, in particular focusing on LQT1, LQT2, and LQT3, and discuss novel strategies to study ion channel dysfunction and drug-specific therapies in LQT1, LQT2, and LQT3 syndromes.
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Affiliation(s)
| | - Isabelle Deschênes
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, Ohio
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20
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Properties of Calmodulin Binding to Na V1.2 IQ Motif and Its Autism-Associated Mutation R1902C. Neurochem Res 2021; 46:523-534. [PMID: 33394222 DOI: 10.1007/s11064-020-03189-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 11/15/2020] [Accepted: 11/26/2020] [Indexed: 01/08/2023]
Abstract
Voltage-gated sodium channels (VGSCs) are fundamental to the initiation and propagation of action potentials in excitable cells. Ca2+/calmodulin (CaM) binds to VGSC type II (NaV1.2) isoleucine and glutamine (IQ) motif. An autism-associated mutation in NaV1.2 IQ motif, Arg1902Cys (R1902C), has been reported to affect the combination between CaM and the IQ motif compared to that of the wild type IQ motif. However, the detailed properties for the Ca2+-regulated binding of CaM to NaV1.2 IQ (1901Lys-1927Lys, IQwt) and mutant IQ motif (IQR1902C) remains unclear. Here, the binding ability of CaM and CaM's constituent proteins including N- and C lobe to the IQ motif of NaV1.2 and its mutant was investigated by protein pull-down experiments. We discovered that the combination between CaM and the IQ motif was U-shaped with the highest at [Ca2+] ≈ free and the lowest at 100 nM [Ca2+]. In the IQR1902C mutant, Ca2+-dependence of CaM binding was nearly lost. Consequently, the binding of CaM to IQR1902C at 100 and 500 nM [Ca2+] was increased compared to that of IQwt. Both N- and C lobe of CaM could bind with NaV1.2 IQ motif and IQR1902C mutant, with the major effect of C lobe. Furthermore, CaMKII had no impact on the binding between CaM and NaV1.2 IQ motif. This research offers novel insight to the regulation of NaV1.2 IQwt and IQR1902C motif, an autism-associated mutation, by CaM.
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21
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Wang Z, Vermij SH, Sottas V, Shestak A, Ross-Kaschitza D, Zaklyazminskaya EV, Hudmon A, Pitt GS, Rougier JS, Abriel H. Calmodulin binds to the N-terminal domain of the cardiac sodium channel Na v1.5. Channels (Austin) 2020; 14:268-286. [PMID: 32815768 PMCID: PMC7515574 DOI: 10.1080/19336950.2020.1805999] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The cardiac voltage-gated sodium channel Nav1.5 conducts the rapid inward sodium current crucial for cardiomyocyte excitability. Loss-of-function mutations in its gene SCN5A are linked to cardiac arrhythmias such as Brugada Syndrome (BrS). Several BrS-associated mutations in the Nav1.5 N-terminal domain (NTD) exert a dominant-negative effect (DNE) on wild-type channel function, for which mechanisms remain poorly understood. We aim to contribute to the understanding of BrS pathophysiology by characterizing three mutations in the Nav1.5 NTD: Y87C-here newly identified-, R104W, and R121W. In addition, we hypothesize that the calcium sensor protein calmodulin is a new NTD binding partner. Recordings of whole-cell sodium currents in TsA-201 cells expressing WT and variant Nav1.5 showed that Y87C and R104W but not R121W exert a DNE on WT channels. Biotinylation assays revealed reduction in fully glycosylated Nav1.5 at the cell surface and in whole-cell lysates. Localization of Nav1.5 WT channel with the ER did not change in the presence of variants, as shown by transfected and stained rat neonatal cardiomyocytes. We demonstrated that calmodulin binds the Nav1.5 NTD using in silico modeling, SPOTS, pull-down, and proximity ligation assays. Calmodulin binding to the R121W variant and to a Nav1.5 construct missing residues 80-105, a predicted calmodulin-binding site, is impaired. In conclusion, we describe the new natural BrS Nav1.5 variant Y87C and present first evidence that calmodulin binds to the Nav1.5 NTD, which seems to be a determinant for the DNE.
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Affiliation(s)
- Zizun Wang
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland
| | - Sarah H. Vermij
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland
| | - Valentin Sottas
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland
- Department of Molecular and Cellular Genetics, Lonza BioPharma Ltd, Visp, Switzerland
| | - Anna Shestak
- Ibex, Petrovskiy Russian Scientific Center of Surgery, Moscow, Russia
| | | | | | - Andy Hudmon
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, Indiana, USA
| | - Geoffrey S. Pitt
- Cardiovascular Research Institute, Weill Cornell Medical College, New York, USA
| | | | - Hugues Abriel
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland
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22
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Abrams J, Roybal D, Chakouri N, Katchman AN, Weinberg R, Yang L, Chen BX, Zakharov SI, Hennessey JA, Avula UMR, Diaz J, Wang C, Wan EY, Pitt GS, Ben-Johny M, Marx SO. Fibroblast growth factor homologous factors tune arrhythmogenic late NaV1.5 current in calmodulin binding-deficient channels. JCI Insight 2020; 5:141736. [PMID: 32870823 PMCID: PMC7566708 DOI: 10.1172/jci.insight.141736] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 08/26/2020] [Indexed: 12/19/2022] Open
Abstract
The Ca2+-binding protein calmodulin has emerged as a pivotal player in tuning Na+ channel function, although its impact in vivo remains to be resolved. Here, we identify the role of calmodulin and the NaV1.5 interactome in regulating late Na+ current in cardiomyocytes. We created transgenic mice with cardiac-specific expression of human NaV1.5 channels with alanine substitutions for the IQ motif (IQ/AA). The mutations rendered the channels incapable of binding calmodulin to the C-terminus. The IQ/AA transgenic mice exhibited normal ventricular repolarization without arrhythmias and an absence of increased late Na+ current. In comparison, transgenic mice expressing a lidocaine-resistant (F1759A) human NaV1.5 demonstrated increased late Na+ current and prolonged repolarization in cardiomyocytes, with spontaneous arrhythmias. To determine regulatory factors that prevent late Na+ current for the IQ/AA mutant channel, we considered fibroblast growth factor homologous factors (FHFs), which are within the NaV1.5 proteomic subdomain shown by proximity labeling in transgenic mice expressing NaV1.5 conjugated to ascorbate peroxidase. We found that FGF13 diminished late current of the IQ/AA but not F1759A mutant cardiomyocytes, suggesting that endogenous FHFs may serve to prevent late Na+ current in mouse cardiomyocytes. Leveraging endogenous mechanisms may furnish an alternative avenue for developing novel pharmacology that selectively blunts late Na+ current.
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Affiliation(s)
| | | | - Nourdine Chakouri
- Department of Physiology and Cellular Biophysics, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York, USA
| | | | | | - Lin Yang
- Division of Cardiology, Department of Medicine
| | | | | | | | | | - Johanna Diaz
- Department of Physiology and Cellular Biophysics, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York, USA
| | - Chaojian Wang
- Division of Cardiology, Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA
| | | | - Geoffrey S. Pitt
- Cardiovascular Research Institute, Weill Cornell Medical College, New York, New York, USA
| | - Manu Ben-Johny
- Department of Physiology and Cellular Biophysics, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York, USA
| | - Steven O. Marx
- Division of Cardiology, Department of Medicine
- Department of Pharmacology, and
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23
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Adney SK, Millichap JJ, DeKeyser JM, Abramova T, Thompson CH, George AL. Functional and pharmacological evaluation of a novel SCN2A variant linked to early-onset epilepsy. Ann Clin Transl Neurol 2020; 7:1488-1501. [PMID: 32750235 PMCID: PMC7480906 DOI: 10.1002/acn3.51105] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 05/26/2020] [Accepted: 05/28/2020] [Indexed: 11/09/2022] Open
Abstract
OBJECTIVE We identified a novel de novo SCN2A variant (M1879T) associated with infantile-onset epilepsy that responded dramatically to sodium channel blocker antiepileptic drugs. We analyzed the functional and pharmacological consequences of this variant to establish pathogenicity, and to correlate genotype with phenotype and clinical drug response. METHODS The clinical and genetic features of an infant boy with epilepsy are presented. We investigated the effect of the variant using heterologously expressed recombinant human NaV 1.2 channels. We performed whole-cell patch clamp recording to determine the functional consequences and response to carbamazepine. RESULTS The M1879T variant caused disturbances in channel inactivation including substantially depolarized voltage dependence of inactivation, slower time course of inactivation, and enhanced resurgent current that collectively represent a gain-of-function. Carbamazepine partially normalized the voltage dependence of inactivation and produced use-dependent block of the variant channel at high pulsing frequencies. Carbamazepine also suppresses resurgent current conducted by M1879T channels, but this effect was explained primarily by reducing the peak transient current. Molecular modeling suggests that the M1879T variant disrupts contacts with nearby residues in the C-terminal domain of the channel. INTERPRETATION Our study demonstrates the value of conducting functional analyses of SCN2A variants of unknown significance to establish pathogenicity and genotype-phenotype correlations. We also show concordance of in vitro pharmacology using heterologous cells with the drug response observed clinically in a case of SCN2A-associated epilepsy.
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Affiliation(s)
- Scott K Adney
- Ken and Ruth Davee Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, 60611, USA
| | - John J Millichap
- Department of Pediatrics, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, 60611, USA.,Ann and Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, 60611, USA
| | - Jean-Marc DeKeyser
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Tatiana Abramova
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Christopher H Thompson
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Alfred L George
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
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24
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Saadeh K, Achercouk Z, Fazmin IT, Nantha Kumar N, Salvage SC, Edling CE, Huang CLH, Jeevaratnam K. Protein expression profiles in murine ventricles modeling catecholaminergic polymorphic ventricular tachycardia: effects of genotype and sex. Ann N Y Acad Sci 2020; 1478:63-74. [PMID: 32713021 DOI: 10.1111/nyas.14426] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 05/27/2020] [Accepted: 06/15/2020] [Indexed: 12/12/2022]
Abstract
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is associated with mutations in the cardiac ryanodine receptor (RyR2). These result in stress-induced ventricular arrhythmic episodes, with clinical symptoms and prognosis reported more severe in male than female patients. Murine homozygotic RyR2-P2328S (RyR2S/S ) hearts replicate the proarrhythmic CPVT phenotype of abnormal sarcoplasmic reticular Ca2+ leak and disrupted Ca2+ homeostasis. In addition, RyR2S/S hearts show decreased myocardial action potential conduction velocities (CV), all features implicated in arrhythmic trigger and substrate. The present studies explored for independent and interacting effects of RyR2S/S genotype and sex on expression levels of molecular determinants of Ca2+ homeostasis (CASQ2, FKBP12, SERCA2a, NCX1, and CaV 1.2) and CV (NaV 1.5, Connexin (Cx)-43, phosphorylated-Cx43, and TGF-β1) in mice. Expression levels of Ca2+ homeostasis proteins were not altered, hence implicating abnormal RyR2 function alone in disrupted cytosolic Ca2+ homeostasis. Furthermore, altered NaV 1.5, phosphorylated Cx43, and TGF-β1 expression were not implicated in the development of slowed CV. By contrast, decreased Cx43 expression correlated with slowed CV, in female, but not male, RyR2S/S mice. The CV changes may reflect acute actions of the increased cytosolic Ca2+ on NaV 1.5 and Cx43 function.
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Affiliation(s)
- Khalil Saadeh
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom.,School of Clinical Medicine, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
| | - Zakaria Achercouk
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Ibrahim T Fazmin
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom.,School of Clinical Medicine, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
| | - Nakulan Nantha Kumar
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom.,Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Samantha C Salvage
- Physiological Laboratory, University of Cambridge, Cambridge, United Kingdom.,Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Charlotte E Edling
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Christopher L-H Huang
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom.,Physiological Laboratory, University of Cambridge, Cambridge, United Kingdom.,Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Kamalan Jeevaratnam
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom.,Physiological Laboratory, University of Cambridge, Cambridge, United Kingdom
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25
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Brewer KR, Kuenze G, Vanoye CG, George AL, Meiler J, Sanders CR. Structures Illuminate Cardiac Ion Channel Functions in Health and in Long QT Syndrome. Front Pharmacol 2020; 11:550. [PMID: 32431610 PMCID: PMC7212895 DOI: 10.3389/fphar.2020.00550] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 04/09/2020] [Indexed: 12/13/2022] Open
Abstract
The cardiac action potential is critical to the production of a synchronized heartbeat. This electrical impulse is governed by the intricate activity of cardiac ion channels, among them the cardiac voltage-gated potassium (Kv) channels KCNQ1 and hERG as well as the voltage-gated sodium (Nav) channel encoded by SCN5A. Each channel performs a highly distinct function, despite sharing a common topology and structural components. These three channels are also the primary proteins mutated in congenital long QT syndrome (LQTS), a genetic condition that predisposes to cardiac arrhythmia and sudden cardiac death due to impaired repolarization of the action potential and has a particular proclivity for reentrant ventricular arrhythmias. Recent cryo-electron microscopy structures of human KCNQ1 and hERG, along with the rat homolog of SCN5A and other mammalian sodium channels, provide atomic-level insight into the structure and function of these proteins that advance our understanding of their distinct functions in the cardiac action potential, as well as the molecular basis of LQTS. In this review, the gating, regulation, LQTS mechanisms, and pharmacological properties of KCNQ1, hERG, and SCN5A are discussed in light of these recent structural findings.
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Affiliation(s)
- Kathryn R. Brewer
- Center for Structural Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Department of Biochemistry, Vanderbilt University, Nashville, TN, United States
| | - Georg Kuenze
- Center for Structural Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States
| | - Carlos G. Vanoye
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Alfred L. George
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Jens Meiler
- Center for Structural Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States
- Department of Pharmacology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Institute for Drug Discovery, Leipzig University Medical School, Leipzig, Germany
| | - Charles R. Sanders
- Center for Structural Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Department of Biochemistry, Vanderbilt University, Nashville, TN, United States
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26
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Horváth B, Hézső T, Kiss D, Kistamás K, Magyar J, Nánási PP, Bányász T. Late Sodium Current Inhibitors as Potential Antiarrhythmic Agents. Front Pharmacol 2020; 11:413. [PMID: 32372952 PMCID: PMC7184885 DOI: 10.3389/fphar.2020.00413] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Accepted: 03/18/2020] [Indexed: 12/19/2022] Open
Abstract
Based on recent findings, an increased late sodium current (INa,late) plays an important pathophysiological role in cardiac diseases, including rhythm disorders. The article first describes what is INa,late and how it functions under physiological circumstances. Next, it shows the wide range of cellular mechanisms that can contribute to an increased INa,late in heart diseases, and also discusses how the upregulated INa,late can play a role in the generation of cardiac arrhythmias. The last part of the article is about INa,late inhibiting drugs as potential antiarrhythmic agents, based on experimental and preclinical data as well as in the light of clinical trials.
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Affiliation(s)
- Balázs Horváth
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Faculty of Pharmacy, University of Debrecen, Debrecen, Hungary
| | - Tamás Hézső
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Dénes Kiss
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Kornél Kistamás
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - János Magyar
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Division of Sport Physiology, University of Debrecen, Debrecen, Hungary
| | - Péter P. Nánási
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Department of Dental Physiology and Pharmacology, Faculty of Dentistry, University of Debrecen, Debrecen, Hungary
| | - Tamás Bányász
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
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27
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Takla M, Huang CLH, Jeevaratnam K. The cardiac CaMKII-Na v1.5 relationship: From physiology to pathology. J Mol Cell Cardiol 2020; 139:190-200. [PMID: 31958466 DOI: 10.1016/j.yjmcc.2019.12.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 11/20/2019] [Accepted: 12/30/2019] [Indexed: 12/19/2022]
Abstract
The SCN5A gene encodes Nav1.5, which, as the cardiac voltage-gated Na+ channel's pore-forming α subunit, is crucial for the initiation and propagation of atrial and ventricular action potentials. The arrhythmogenic propensity of inherited SCN5A mutations implicates the Na+ channel in determining cardiomyocyte excitability under normal conditions. Cytosolic kinases have long been known to alter the kinetic profile of Nav1.5 inactivation via phosphorylation of specific residues. Recent substantiation of both the role of calmodulin-dependent kinase II (CaMKII) in modulating the properties of the Nav1.5 inactivation gate and the significant rise in oxidation-dependent autonomous CaMKII activity in structural heart disease has raised the possibility of a novel pathway for acquired arrhythmias - the CaMKII-Nav1.5 relationship. The aim of this review is to: (1) outline the relationship's translation from physiological adaptation to pathological vicious circle; and (2) discuss the relative merits of each of its components as pharmacological targets.
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Affiliation(s)
- Michael Takla
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, GU2 7AL, United Kingdom
| | - Christopher L-H Huang
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, GU2 7AL, United Kingdom; Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, CB2 3EG, United Kingdom
| | - Kamalan Jeevaratnam
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, GU2 7AL, United Kingdom; Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, CB2 3EG, United Kingdom.
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28
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Nof E, Vysochek L, Meisel E, Burashnikov E, Antzelevitch C, Clatot J, Beinart R, Luria D, Glikson M, Oz S. Mutations in Na V1.5 Reveal Calcium-Calmodulin Regulation of Sodium Channel. Front Physiol 2019; 10:700. [PMID: 31231243 PMCID: PMC6560087 DOI: 10.3389/fphys.2019.00700] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 05/20/2019] [Indexed: 12/02/2022] Open
Abstract
Mutations in the SCN5A gene, encoding the cardiac voltage-gated sodium channel NaV1.5, are associated with inherited cardiac arrhythmia and conduction disease. Ca2+-dependent mechanisms and the involvement of β-subunit (NaVβ) in NaV1.5 regulation are not fully understood. A patient with severe sinus-bradycardia and cardiac conduction-disease was genetically evaluated and compound heterozygosity in the SCN5A gene was found. Mutations were identified in the cytoplasmic DIII-IV linker (K1493del) and the C-terminus (A1924T) of NaV1.5, both are putative CaM-binding domains. These mutants were functionally studied in human embryonic kidney (HEK) cells and HL-1 cells using whole-cell patch clamp technique. Calmodulin (CaM) interaction and cell-surface expression of heterologously expressed NaV1.5 mutants were studied by pull-down and biotinylation assays. The mutation K1493del rendered NaV1.5 non-conductive. NaV1.5K1493del altered the gating properties of co-expressed functional NaV1.5, in a Ca2+ and NaVβ1-dependent manner. NaV1.5A1924T impaired NaVβ1-dependent gating regulation. Ca2+-dependent CaM-interaction with NaV1.5 was blunted in NaV1.5K1493del. Electrical charge substitution at position 1493 did not affect CaM-interaction and channel functionality. Arrhythmia and conduction-disease -associated mutations revealed Ca2+-dependent gating regulation of NaV1.5 channels. Our results highlight the role of NaV1.5 DIII-IV linker in the CaM-binding complex and channel function, and suggest that the Ca2+-sensing machinery of NaV1.5 involves NaVβ1.
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Affiliation(s)
- Eyal Nof
- Heart Center, Sheba Medical Center, Ramat Gan, Israel.,Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | | | - Eshcar Meisel
- Heart Center, Sheba Medical Center, Ramat Gan, Israel.,Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Elena Burashnikov
- Lankenau Institute for Medical Research, Wynnewood, PA, United States
| | - Charles Antzelevitch
- Lankenau Institute for Medical Research, Wynnewood, PA, United States.,Lankenau Heart Institute, Wynnewood, PA, United States.,Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, United States
| | - Jerome Clatot
- Lankenau Institute for Medical Research, Wynnewood, PA, United States
| | - Roy Beinart
- Heart Center, Sheba Medical Center, Ramat Gan, Israel.,Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - David Luria
- Heart Center, Sheba Medical Center, Ramat Gan, Israel
| | - Michael Glikson
- Heart Center, Sheba Medical Center, Ramat Gan, Israel.,Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Shimrit Oz
- Heart Center, Sheba Medical Center, Ramat Gan, Israel
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29
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Crystal structures of Ca 2+-calmodulin bound to Na V C-terminal regions suggest role for EF-hand domain in binding and inactivation. Proc Natl Acad Sci U S A 2019; 116:10763-10772. [PMID: 31072926 DOI: 10.1073/pnas.1818618116] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Voltage-gated sodium (NaV) and calcium channels (CaV) form targets for calmodulin (CaM), which affects channel inactivation properties. A major interaction site for CaM resides in the C-terminal (CT) region, consisting of an IQ domain downstream of an EF-hand domain. We present a crystal structure of fully Ca2+-occupied CaM, bound to the CT of NaV1.5. The structure shows that the C-terminal lobe binds to a site ∼90° rotated relative to a previous site reported for an apoCaM complex with the NaV1.5 CT and for ternary complexes containing fibroblast growth factor homologous factors (FHF). We show that the binding of FHFs forces the EF-hand domain in a conformation that does not allow binding of the Ca2+-occupied C-lobe of CaM. These observations highlight the central role of the EF-hand domain in modulating the binding mode of CaM. The binding sites for Ca2+-free and Ca2+-occupied CaM contain targets for mutations linked to long-QT syndrome, a type of inherited arrhythmia. The related NaV1.4 channel has been shown to undergo Ca2+-dependent inactivation (CDI) akin to CaVs. We present a crystal structure of Ca2+/CaM bound to the NaV1.4 IQ domain, which shows a binding mode that would clash with the EF-hand domain. We postulate the relative reorientation of the EF-hand domain and the IQ domain as a possible conformational switch that underlies CDI.
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30
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Ca 2+-dependent regulation of sodium channels Na V1.4 and Na V1.5 is controlled by the post-IQ motif. Nat Commun 2019; 10:1514. [PMID: 30944319 PMCID: PMC6447637 DOI: 10.1038/s41467-019-09570-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 03/12/2019] [Indexed: 01/01/2023] Open
Abstract
Skeletal muscle voltage-gated Na+ channel (NaV1.4) activity is subject to calmodulin (CaM) mediated Ca2+-dependent inactivation; no such inactivation is observed in the cardiac Na+ channel (NaV1.5). Taken together, the crystal structures of the NaV1.4 C-terminal domain relevant complexes and thermodynamic binding data presented here provide a rationale for this isoform difference. A Ca2+-dependent CaM N-lobe binding site previously identified in NaV1.5 is not present in NaV1.4 allowing the N-lobe to signal other regions of the NaV1.4 channel. Consistent with this mechanism, removing this binding site in NaV1.5 unveils robust Ca2+-dependent inactivation in the previously insensitive isoform. These findings suggest that Ca2+-dependent inactivation is effected by CaM's N-lobe binding outside the NaV C-terminal while CaM's C-lobe remains bound to the NaV C-terminal. As the N-lobe binding motif of NaV1.5 is a mutational hotspot for inherited arrhythmias, the contributions of mutation-induced changes in CDI to arrhythmia generation is an intriguing possibility.
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31
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Johnson CN. Calcium modulation of cardiac sodium channels. J Physiol 2019; 598:2835-2846. [PMID: 30707447 DOI: 10.1113/jp277553] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2018] [Accepted: 01/08/2019] [Indexed: 12/28/2022] Open
Abstract
Modification of voltage-gated Na+ channel (NaV ) function by intracellular Ca2+ has been a topic of much controversy. Early studies relied on measuring NaV function in the absence or presence of intracellular Ca2+ , and generated seemingly disparate results. Subsequent investigations revealed the mechanism(s) of Ca2+ -driven NaV modulation are complex and involve multiple accessory proteins. The Ca2+ -sensing protein calmodulin (CaM) has a central role in tuning NaV function to [Ca2+ ]i , but the mechanism has been obscured by other proteins (such as fibroblast growth factors (FGF) or CaM-dependent kinase II (CaMKII)) that can also modify channel function or exert an influence in a Ca2+ -dependent manner. Significant progress has been made in understanding the architecture of full-length ion channels and the structural and biophysical details of NaV -accessory protein interactions. Interdisciplinary structure-function studies are beginning to resolve the effect each interaction has on NaV gating. Carefully designed structure-guided or strategically selected disease-associated mutations are able to impair NaV -accessory protein interactions without altering other properties of channel function. Recently CaM was found to engage part of NaV 1.5 that is required for channel inactivation with high affinity. Careful impairment of this interaction disrupted NaV 1.5's ability to recover from inactivation. Such results support a paradigm of CaM-facilitated recovery from inactivation (CFRI). How NaV -CaM, CaMKII and FGF/fibroblast growth factor homologous factor interactions affect the timing or function of CFRI in cardiomyocytes remain open questions that are discussed herein. Moreover whether CFRI dysfunction or premature activation underlie certain NaV channelopathies are important questions that will require further investigation.
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Affiliation(s)
- Christopher N Johnson
- The Ohio State Wexner Medical Centre, Dorothy M. Davis Heart & Lung Research Institute, Columbus, OH, USA.,Vanderbilt Centre for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Nashville, TN, USA
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32
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Urrutia J, Aguado A, Muguruza-Montero A, Núñez E, Malo C, Casis O, Villarroel A. The Crossroad of Ion Channels and Calmodulin in Disease. Int J Mol Sci 2019; 20:ijms20020400. [PMID: 30669290 PMCID: PMC6359610 DOI: 10.3390/ijms20020400] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 01/11/2019] [Accepted: 01/16/2019] [Indexed: 01/21/2023] Open
Abstract
Calmodulin (CaM) is the principal Ca2+ sensor in eukaryotic cells, orchestrating the activity of hundreds of proteins. Disease causing mutations at any of the three genes that encode identical CaM proteins lead to major cardiac dysfunction, revealing the importance in the regulation of excitability. In turn, some mutations at the CaM binding site of ion channels cause similar diseases. Here we provide a summary of the two sides of the partnership between CaM and ion channels, describing the diversity of consequences of mutations at the complementary CaM binding domains.
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Affiliation(s)
- Janire Urrutia
- Biofisika Institute (CSIC, UPV/EHU), University of the Basque Country, 48940 Leioa, Spain.
| | - Alejandra Aguado
- Biofisika Institute (CSIC, UPV/EHU), University of the Basque Country, 48940 Leioa, Spain.
| | | | - Eider Núñez
- Biofisika Institute (CSIC, UPV/EHU), University of the Basque Country, 48940 Leioa, Spain.
| | - Covadonga Malo
- Biofisika Institute (CSIC, UPV/EHU), University of the Basque Country, 48940 Leioa, Spain.
| | - Oscar Casis
- Departamento de Fisiología, Facultad de Farmacia, Universidad del País Vasco (UPV/EHU), 01006 Vitoria-Gasteiz, Spain.
| | - Alvaro Villarroel
- Biofisika Institute (CSIC, UPV/EHU), University of the Basque Country, 48940 Leioa, Spain.
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33
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Badone B, Ronchi C, Kotta MC, Sala L, Ghidoni A, Crotti L, Zaza A. Calmodulinopathy: Functional Effects of CALM Mutations and Their Relationship With Clinical Phenotypes. Front Cardiovasc Med 2018; 5:176. [PMID: 30619883 PMCID: PMC6297375 DOI: 10.3389/fcvm.2018.00176] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 11/22/2018] [Indexed: 12/16/2022] Open
Abstract
In spite of the widespread role of calmodulin (CaM) in cellular signaling, CaM mutations lead specifically to cardiac manifestations, characterized by remarkable electrical instability and a high incidence of sudden death at young age. Penetrance of the mutations is surprisingly high, thus postulating a high degree of functional dominance. According to the clinical patterns, arrhythmogenesis in CaM mutations can be attributed, in the majority of cases, to either prolonged repolarization (as in long-QT syndrome, LQTS phenotype), or to instability of the intracellular Ca2+ store (as in catecholamine-induced tachycardias, CPVT phenotype). This review discusses how mutations affect CaM signaling function and how this may relate to the distinct arrhythmia phenotypes/mechanisms observed in patients; this involves mechanistic interpretation of negative dominance and mutation-specific CaM-target interactions. Knowledge of the mechanisms involved may allow critical approach to clinical manifestations and aid in the development of therapeutic strategies for "calmodulinopathies," a recently identified nosological entity.
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Affiliation(s)
- Beatrice Badone
- Department of Biotechnology and Bioscience, University of Milano-Bicocca, Milan, Italy
| | - Carlotta Ronchi
- Department of Biotechnology and Bioscience, University of Milano-Bicocca, Milan, Italy
| | - Maria-Christina Kotta
- Center for Cardiac Arrhythmias of Genetic Origin and Laboratory of Cardiovascular Genetics, Istituto Auxologico Italiano, IRCCS, Milan, Italy
| | - Luca Sala
- Center for Cardiac Arrhythmias of Genetic Origin and Laboratory of Cardiovascular Genetics, Istituto Auxologico Italiano, IRCCS, Milan, Italy
| | - Alice Ghidoni
- Center for Cardiac Arrhythmias of Genetic Origin and Laboratory of Cardiovascular Genetics, Istituto Auxologico Italiano, IRCCS, Milan, Italy
| | - Lia Crotti
- Center for Cardiac Arrhythmias of Genetic Origin and Laboratory of Cardiovascular Genetics, Istituto Auxologico Italiano, IRCCS, Milan, Italy
- Department of Medicine and Surgery, University of Milano-Bicocca, Milan, Italy
- Department of Cardiovascular, Neural and Metabolic Sciences, San Luca Hospital, Istituto Auxologico Italiano, IRCCS, Milan, Italy
| | - Antonio Zaza
- Department of Biotechnology and Bioscience, University of Milano-Bicocca, Milan, Italy
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34
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Isbell HM, Kilpatrick AM, Lin Z, Mahling R, Shea MA. Backbone resonance assignments of complexes of apo human calmodulin bound to IQ motif peptides of voltage-dependent sodium channels Na V1.1, Na V1.4 and Na V1.7. BIOMOLECULAR NMR ASSIGNMENTS 2018; 12:283-289. [PMID: 29728980 PMCID: PMC6274588 DOI: 10.1007/s12104-018-9824-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 04/29/2018] [Indexed: 06/08/2023]
Abstract
Human voltage-gated sodium (NaV) channels are critical for initiating and propagating action potentials in excitable cells. Nine isoforms have different roles but similar topologies, with a pore-forming α-subunit and auxiliary transmembrane β-subunits. NaV pathologies lead to debilitating conditions including epilepsy, chronic pain, cardiac arrhythmias, and skeletal muscle paralysis. The ubiquitous calcium sensor calmodulin (CaM) binds to an IQ motif in the C-terminal tail of the α-subunit of all NaV isoforms, and contributes to calcium-dependent pore-gating in some channels. Previous structural studies of calcium-free (apo) CaM bound to the IQ motifs of NaV1.2, NaV1.5, and NaV1.6 showed that CaM binding was mediated by the C-domain of CaM (CaMC), while the N-domain (CaMN) made no detectable contacts. To determine whether this domain-specific recognition mechanism is conserved in other NaV isoforms, we used solution NMR spectroscopy to assign the backbone resonances of complexes of apo CaM bound to peptides of IQ motifs of NaV1.1, NaV1.4, and NaV1.7. Analysis of chemical shift differences showed that peptide binding only perturbed resonances in CaMC; resonances of CaMN were identical to free CaM. Thus, CaMC residues contribute to the interface with the IQ motif, while CaMN is available to interact elsewhere on the channel.
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Affiliation(s)
- Holly M Isbell
- Department of Biochemistry, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, 52242-1109, USA
| | - Adina M Kilpatrick
- Department of Physics and Astronomy, Drake University, Des Moines, IA, 50311-4516, USA
| | - Zesen Lin
- Department of Biochemistry, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, 52242-1109, USA
| | - Ryan Mahling
- Department of Biochemistry, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, 52242-1109, USA
| | - Madeline A Shea
- Department of Biochemistry, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA, 52242-1109, USA.
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Voltage-dependent inward currents in smooth muscle cells of skeletal muscle arterioles. PLoS One 2018; 13:e0194980. [PMID: 29694371 PMCID: PMC5919073 DOI: 10.1371/journal.pone.0194980] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 03/08/2018] [Indexed: 01/14/2023] Open
Abstract
Voltage-dependent inward currents responsible for the depolarizing phase of action potentials were characterized in smooth muscle cells of 4th order arterioles in mouse skeletal muscle. Currents through L-type Ca2+ channels were expected to be dominant; however, action potentials were not eliminated in nominally Ca2+-free bathing solution or by addition of L-type Ca2+ channel blocker nifedipine (10 μM). Instead, Na+ channel blocker tetrodotoxin (TTX, 1 μM) reduced the maximal velocity of the upstroke at low, but not at normal (2 mM), Ca2+ in the bath. The magnitude of TTX-sensitive currents recorded with 140 mM Na+ was about 20 pA/pF. TTX-sensitive currents decreased five-fold when Ca2+ increased from 2 to 10 mM. The currents reduced three-fold in the presence of 10 mM caffeine, but remained unaltered by 1 mM of isobutylmethylxanthine (IBMX). In addition to L-type Ca2+ currents (15 pA/pF in 20 mM Ca2+), we also found Ca2+ currents that are resistant to 10 μM nifedipine (5 pA/pF in 20 mM Ca2+). Based on their biophysical properties, these Ca2+ currents are likely to be through voltage-gated T-type Ca2+ channels. Our results suggest that Na+ and at least two types (T- and L-) of Ca2+ voltage-gated channels contribute to depolarization of smooth muscle cells in skeletal muscle arterioles. Voltage-gated Na+ channels appear to be under a tight control by Ca2+ signaling.
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36
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Sanders SJ, Campbell AJ, Cottrell JR, Moller RS, Wagner FF, Auldridge AL, Bernier RA, Catterall WA, Chung WK, Empfield JR, George AL, Hipp JF, Khwaja O, Kiskinis E, Lal D, Malhotra D, Millichap JJ, Otis TS, Petrou S, Pitt G, Schust LF, Taylor CM, Tjernagel J, Spiro JE, Bender KJ. Progress in Understanding and Treating SCN2A-Mediated Disorders. Trends Neurosci 2018; 41:442-456. [PMID: 29691040 DOI: 10.1016/j.tins.2018.03.011] [Citation(s) in RCA: 189] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 03/09/2018] [Accepted: 03/14/2018] [Indexed: 01/20/2023]
Abstract
Advances in gene discovery for neurodevelopmental disorders have identified SCN2A dysfunction as a leading cause of infantile seizures, autism spectrum disorder, and intellectual disability. SCN2A encodes the neuronal sodium channel NaV1.2. Functional assays demonstrate strong correlation between genotype and phenotype. This insight can help guide therapeutic decisions and raises the possibility that ligands that selectively enhance or diminish channel function may improve symptoms. The well-defined function of sodium channels makes SCN2A an important test case for investigating the neurobiology of neurodevelopmental disorders more generally. Here, we discuss the progress made, through the concerted efforts of a diverse group of academic and industry scientists as well as policy advocates, in understanding and treating SCN2A-related disorders.
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Affiliation(s)
- Stephan J Sanders
- Department of Psychiatry, UCSF Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA 94158, USA.
| | - Arthur J Campbell
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, 75 Ames Street, Cambridge, MA 02142, USA
| | - Jeffrey R Cottrell
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, 75 Ames Street, Cambridge, MA 02142, USA
| | - Rikke S Moller
- The Danish Epilepsy Centre, Dianalund, Denmark; Institute for Regional Health Services, University of Southern Denmark, Campusvej 55, 5230 Odense, Denmark
| | - Florence F Wagner
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, 75 Ames Street, Cambridge, MA 02142, USA
| | - Angie L Auldridge
- FamilieSCN2a Foundation, P.O. Box 82, East Longmeadow, MA 01028, USA
| | - Raphael A Bernier
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA 98195, USA
| | - William A Catterall
- Department of Pharmacology, University of Washington, Seattle, WA 98195-7280, USA
| | - Wendy K Chung
- Simons Foundation, New York, NY 10010, USA; Department of Pediatrics and Medicine, Columbia University, New York, NY 10032, USA
| | - James R Empfield
- Xenon Pharmaceuticals Inc., 3650 Gilmore Way, Burnaby, BC V5G 4W8, Canada
| | - Alfred L George
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Joerg F Hipp
- Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Omar Khwaja
- Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Evangelos Kiskinis
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA; Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Dennis Lal
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, 75 Ames Street, Cambridge, MA 02142, USA
| | - Dheeraj Malhotra
- Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - John J Millichap
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA; Epilepsy Center and Division of Neurology, Ann & Robert H. Lurie Children's Hospital of Chicago, IL 60611, USA; Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Thomas S Otis
- Sainsbury Wellcome Centre for Neural Circuits and Behaviour, University College London, 25 Howland Street, London W1T 4JG, UK
| | - Steven Petrou
- Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
| | - Geoffrey Pitt
- Cardiovascular Research Institute, Weill Cornell Medical College, Cornell University, New York, NY 10065, USA
| | - Leah F Schust
- FamilieSCN2a Foundation, P.O. Box 82, East Longmeadow, MA 01028, USA
| | - Cora M Taylor
- Geisinger Health System, 100 North Academy Avenue, Danville, PA 17822, USA
| | | | | | - Kevin J Bender
- Department of Neurology, UCSF Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA 94158, USA.
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Edokobi N, Isom LL. Voltage-Gated Sodium Channel β1/β1B Subunits Regulate Cardiac Physiology and Pathophysiology. Front Physiol 2018; 9:351. [PMID: 29740331 PMCID: PMC5924814 DOI: 10.3389/fphys.2018.00351] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 03/20/2018] [Indexed: 12/19/2022] Open
Abstract
Cardiac myocyte contraction is initiated by a set of intricately orchestrated electrical impulses, collectively known as action potentials (APs). Voltage-gated sodium channels (NaVs) are responsible for the upstroke and propagation of APs in excitable cells, including cardiomyocytes. NaVs consist of a single, pore-forming α subunit and two different β subunits. The β subunits are multifunctional cell adhesion molecules and channel modulators that have cell type and subcellular domain specific functional effects. Variants in SCN1B, the gene encoding the Nav-β1 and -β1B subunits, are linked to atrial and ventricular arrhythmias, e.g., Brugada syndrome, as well as to the early infantile epileptic encephalopathy Dravet syndrome, all of which put patients at risk for sudden death. Evidence over the past two decades has demonstrated that Nav-β1/β1B subunits play critical roles in cardiac myocyte physiology, in which they regulate tetrodotoxin-resistant and -sensitive sodium currents, potassium currents, and calcium handling, and that Nav-β1/β1B subunit dysfunction generates substrates for arrhythmias. This review will highlight the role of Nav-β1/β1B subunits in cardiac physiology and pathophysiology.
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Affiliation(s)
| | - Lori L. Isom
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, United States
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Gardill BR, Rivera-Acevedo RE, Tung CC, Okon M, McIntosh LP, Van Petegem F. The voltage-gated sodium channel EF-hands form an interaction with the III-IV linker that is disturbed by disease-causing mutations. Sci Rep 2018; 8:4483. [PMID: 29540853 PMCID: PMC5852250 DOI: 10.1038/s41598-018-22713-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 02/27/2018] [Indexed: 12/20/2022] Open
Abstract
Voltage-gated sodium channels (NaV) are responsible for the rapid depolarization of many excitable cells. They readily inactivate, a process where currents diminish after milliseconds of channel opening. They are also targets for a multitude of disease-causing mutations, many of which have been shown to affect inactivation. A cluster of disease mutations, linked to Long-QT and Brugada syndromes, is located in a C-terminal EF-hand like domain of NaV1.5, the predominant cardiac sodium channel isoform. Previous studies have suggested interactions with the III-IV linker, a cytosolic element directly involved in inactivation. Here we validate and map the interaction interface using isothermal titration calorimetry (ITC) and NMR spectroscopy. We investigated the impact of various disease mutations on the stability of the domain, and found that mutations that cause misfolding of the EF-hand domain result in hyperpolarizing shifts in the steady-state inactivation curve. Conversely, mutations in the III-IV linker that disrupt the interaction with the EF-hand domain also result in large hyperpolarization shifts, supporting the interaction between both elements in intact channels. Disrupting the interaction also causes large late currents, pointing to a dual role of the interaction in reducing the population of channels entering inactivation and in stabilizing the inactivated state.
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Affiliation(s)
- Bernd R Gardill
- Department of Biochemistry and Molecular Biology, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Ricardo E Rivera-Acevedo
- Department of Biochemistry and Molecular Biology, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
- Department of Anesthesiology, Pharmacology, and Therapeutics, The University of British Columbia, 2176 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Ching-Chieh Tung
- Department of Biochemistry and Molecular Biology, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Mark Okon
- Department of Biochemistry and Molecular Biology, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
- Department of Chemistry, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Lawrence P McIntosh
- Department of Biochemistry and Molecular Biology, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
- Department of Chemistry, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada.
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Abdelsayed M, Ruprai M, Ruben PC. The efficacy of Ranolazine on E1784K is altered by temperature and calcium. Sci Rep 2018; 8:3643. [PMID: 29483621 PMCID: PMC5827758 DOI: 10.1038/s41598-018-22033-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 02/15/2018] [Indexed: 12/19/2022] Open
Abstract
E1784K is the most common mixed syndrome SCN5a mutation underpinning both Brugada syndrome type 1 (BrS1) and Long-QT syndrome type 3 (LQT3). The charge reversal mutant enhances the late sodium current (INa) passed by the cardiac voltage-gated sodium channel (NaV1.5), delaying cardiac repolarization. Exercise-induced triggers, like elevated temperature and cytosolic calcium, exacerbate E1784K late INa. In this study, we tested the effects of Ranolazine, the late INa blocker, on voltage-dependent and kinetic properties of E1784K at elevated temperature and cytosolic calcium. We used whole-cell patch clamp to measure INa from wild type and E1784K channels expressed in HEK293 cells. At elevated temperature, Ranolazine attenuated gain-of-function in E1784K by decreasing late INa, hyperpolarizing steady-state fast inactivation, and increasing use-dependent inactivation. Both elevated temperature and cytosolic calcium hampered the capacity of Ranolazine to suppress E1784K late INa. In-silico action potential (AP) simulations were done using a modified O'Hara Rudy (ORd) cardiac model. Simulations showed that Ranolazine failed to shorten AP duration, an effect augmented at febrile temperatures. The drug-channel interaction is clearly affected by external triggers, as reported previously with ischemia. Determining drug efficacy under various physiological states in SCN5a cohorts is crucial for accurate management of arrhythmias.
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Affiliation(s)
- Mena Abdelsayed
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A 1S6, Canada
| | - Manpreet Ruprai
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A 1S6, Canada
| | - Peter C Ruben
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A 1S6, Canada.
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40
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Direct visualization of interaction between calmodulin and connexin45. Biochem J 2017; 474:4035-4051. [PMID: 28963343 DOI: 10.1042/bcj20170426] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 09/12/2017] [Accepted: 09/25/2017] [Indexed: 01/21/2023]
Abstract
Calmodulin (CaM) is an intracellular Ca2+ transducer involved in numerous activities in a broad Ca2+ signaling network. Previous studies have suggested that the Ca2+/CaM complex may participate in gap junction regulation via interaction with putative CaM-binding motifs in connexins; however, evidence of direct interactions between CaM and connexins has remained elusive to date due to challenges related to the study of membrane proteins. Here, we report the first direct interaction of CaM with Cx45 (connexin45) of γ-family in living cells under physiological conditions by monitoring bioluminescence resonance energy transfer. The interaction between CaM and Cx45 in cells is strongly dependent on intracellular Ca2+ concentration and can be blocked by the CaM inhibitor, N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide hydrochloride (W7). We further reveal a CaM-binding site at the cytosolic loop (residues 164-186) of Cx45 using a peptide model. The strong binding (Kd ∼ 5 nM) observed between CaM and Cx45 peptide, monitored by fluorescence-labeled CaM, is found to be Ca2+-dependent. Furthermore, high-resolution nuclear magnetic resonance spectroscopy reveals that CaM and Cx45 peptide binding leads to global chemical shift changes of 15N-labeled CaM, but does not alter the size of the structure. Observations involving both N- and C-domains of CaM to interact with the Cx45 peptide differ from the embraced interaction with Cx50 from another connexin family. Such interaction further increases Ca2+ sensitivity of CaM, especially at the N-terminal domain. Results of the present study suggest that both helicity and the interaction mode of the cytosolic loop are likely to contribute to CaM's modulation of connexins.
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41
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Burel S, Coyan FC, Lorenzini M, Meyer MR, Lichti CF, Brown JH, Loussouarn G, Charpentier F, Nerbonne JM, Townsend RR, Maier LS, Marionneau C. C-terminal phosphorylation of Na V1.5 impairs FGF13-dependent regulation of channel inactivation. J Biol Chem 2017; 292:17431-17448. [PMID: 28882890 PMCID: PMC5655519 DOI: 10.1074/jbc.m117.787788] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 08/23/2017] [Indexed: 11/06/2022] Open
Abstract
Voltage-gated Na+ (NaV) channels are key regulators of myocardial excitability, and Ca2+/calmodulin-dependent protein kinase II (CaMKII)-dependent alterations in NaV1.5 channel inactivation are emerging as a critical determinant of arrhythmias in heart failure. However, the global native phosphorylation pattern of NaV1.5 subunits associated with these arrhythmogenic disorders and the associated channel regulatory defects remain unknown. Here, we undertook phosphoproteomic analyses to identify and quantify in situ the phosphorylation sites in the NaV1.5 proteins purified from adult WT and failing CaMKIIδc-overexpressing (CaMKIIδc-Tg) mouse ventricles. Of 19 native NaV1.5 phosphorylation sites identified, two C-terminal phosphoserines at positions 1938 and 1989 showed increased phosphorylation in the CaMKIIδc-Tg compared with the WT ventricles. We then tested the hypothesis that phosphorylation at these two sites impairs fibroblast growth factor 13 (FGF13)-dependent regulation of NaV1.5 channel inactivation. Whole-cell voltage-clamp analyses in HEK293 cells demonstrated that FGF13 increases NaV1.5 channel availability and decreases late Na+ current, two effects that were abrogated with NaV1.5 mutants mimicking phosphorylation at both sites. Additional co-immunoprecipitation experiments revealed that FGF13 potentiates the binding of calmodulin to NaV1.5 and that phosphomimetic mutations at both sites decrease the interaction of FGF13 and, consequently, of calmodulin with NaV1.5. Together, we have identified two novel native phosphorylation sites in the C terminus of NaV1.5 that impair FGF13-dependent regulation of channel inactivation and may contribute to CaMKIIδc-dependent arrhythmogenic disorders in failing hearts.
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Affiliation(s)
- Sophie Burel
- From the l'Institut du Thorax, INSERM, CNRS, UNIV Nantes, Nantes 44007, France
| | - Fabien C Coyan
- From the l'Institut du Thorax, INSERM, CNRS, UNIV Nantes, Nantes 44007, France
| | - Maxime Lorenzini
- From the l'Institut du Thorax, INSERM, CNRS, UNIV Nantes, Nantes 44007, France
| | | | - Cheryl F Lichti
- the Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas 77555
| | - Joan H Brown
- the Department of Pharmacology, University of California at San Diego, La Jolla, California 92093-0636, and
| | - Gildas Loussouarn
- From the l'Institut du Thorax, INSERM, CNRS, UNIV Nantes, Nantes 44007, France
| | - Flavien Charpentier
- From the l'Institut du Thorax, INSERM, CNRS, UNIV Nantes, Nantes 44007, France
| | | | - R Reid Townsend
- Internal Medicine, and
- Cell Biology and Physiology, Washington University Medical School, St. Louis, Missouri 63110
| | - Lars S Maier
- the Department of Internal Medicine II, University Heart Center, University Hospital Regensburg, D-93042 Regensburg, Germany
| | - Céline Marionneau
- From the l'Institut du Thorax, INSERM, CNRS, UNIV Nantes, Nantes 44007, France,
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42
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Yamamoto Y, Makiyama T, Harita T, Sasaki K, Wuriyanghai Y, Hayano M, Nishiuchi S, Kohjitani H, Hirose S, Chen J, Yokoi F, Ishikawa T, Ohno S, Chonabayashi K, Motomura H, Yoshida Y, Horie M, Makita N, Kimura T. Allele-specific ablation rescues electrophysiological abnormalities in a human iPS cell model of long-QT syndrome with a CALM2 mutation. Hum Mol Genet 2017; 26:1670-1677. [PMID: 28335032 DOI: 10.1093/hmg/ddx073] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 02/22/2017] [Indexed: 12/14/2022] Open
Abstract
Calmodulin is a ubiquitous Ca2+ sensor molecule encoded by three distinct calmodulin genes, CALM1-3. Recently, mutations in CALM1-3 have been reported to be associated with severe early-onset long-QT syndrome (LQTS). However, the underlying mechanism through which heterozygous calmodulin mutations lead to severe LQTS remains unknown, particularly in human cardiomyocytes. We aimed to establish an LQTS disease model associated with a CALM2 mutation (LQT15) using human induced pluripotent stem cells (hiPSCs) and to assess mutant allele-specific ablation by genome editing for the treatment of LQT15. We generated LQT15-hiPSCs from a 12-year-old boy with LQTS carrying a CALM2-N98S mutation and differentiated these hiPSCs into cardiomyocytes (LQT15-hiPSC-CMs). Action potentials (APs) and L-type Ca2+ channel (LTCC) currents in hiPSC-CMs were analyzed by the patch-clamp technique and compared with those of healthy controls. Furthermore, we performed mutant allele-specific knockout using a CRISPR-Cas9 system and analyzed electrophysiological properties. Electrophysiological analyses revealed that LQT15-hiPSC-CMs exhibited significantly lower beating rates, prolonged AP durations, and impaired inactivation of LTCC currents compared with control cells, consistent with clinical phenotypes. Notably, ablation of the mutant allele rescued the electrophysiological abnormalities of LQT15-hiPSC-CMs, indicating that the mutant allele caused dominant-negative suppression of LTCC inactivation, resulting in prolonged AP duration. We successfully recapitulated the disease phenotypes of LQT15 and revealed that inactivation of LTCC currents was impaired in CALM2-N98S hiPSC model. Additionally, allele-specific ablation using the latest genome-editing technology provided important insights into a promising therapeutic approach for inherited cardiac diseases.
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Affiliation(s)
- Yuta Yamamoto
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Sakyo-ku, Kyoto 606-8507, Japan
| | - Takeru Makiyama
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Sakyo-ku, Kyoto 606-8507, Japan
| | - Takeshi Harita
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Sakyo-ku, Kyoto 606-8507, Japan
| | - Kenichi Sasaki
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Sakyo-ku, Kyoto 606-8507, Japan
| | - Yimin Wuriyanghai
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Sakyo-ku, Kyoto 606-8507, Japan.,Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Seta-Tsukinowa, Otsu 520-2192, Japan
| | - Mamoru Hayano
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Sakyo-ku, Kyoto 606-8507, Japan
| | - Suguru Nishiuchi
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Sakyo-ku, Kyoto 606-8507, Japan
| | - Hirohiko Kohjitani
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Sakyo-ku, Kyoto 606-8507, Japan
| | - Sayako Hirose
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Sakyo-ku, Kyoto 606-8507, Japan
| | - Jiarong Chen
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Sakyo-ku, Kyoto 606-8507, Japan
| | - Fumika Yokoi
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Sakyo-ku, Kyoto 606-8507, Japan
| | - Taisuke Ishikawa
- Department of Molecular Physiology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki 852-8523, Japan
| | - Seiko Ohno
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Seta-Tsukinowa, Otsu 520-2192, Japan
| | - Kazuhisa Chonabayashi
- Department of Life Science Frontiers, Center for iPS Cell Research and Application, Kyoto University, Sakyo-ku, Kyoto 606-8507, Japan
| | - Hideki Motomura
- Department of Pediatrics, Nagasaki University Hospital, Nagasaki 852-8501, Japan
| | - Yoshinori Yoshida
- Department of Life Science Frontiers, Center for iPS Cell Research and Application, Kyoto University, Sakyo-ku, Kyoto 606-8507, Japan
| | - Minoru Horie
- Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Seta-Tsukinowa, Otsu 520-2192, Japan
| | - Naomasa Makita
- Department of Molecular Physiology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki 852-8523, Japan
| | - Takeshi Kimura
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Sakyo-ku, Kyoto 606-8507, Japan
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43
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Abdelsayed M, Baruteau A, Gibbs K, Sanatani S, Krahn AD, Probst V, Ruben PC. Differential calcium sensitivity in Na V 1.5 mixed syndrome mutants. J Physiol 2017; 595:6165-6186. [PMID: 28734073 PMCID: PMC5599485 DOI: 10.1113/jp274536] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Accepted: 07/21/2017] [Indexed: 01/13/2023] Open
Abstract
KEY POINTS SCN5a mutations may express gain-of-function (Long QT Syndrome-3), loss-of-function (Brugada Syndrome 1) or both (mixed syndromes), depending on the mutation and environmental triggers. One such trigger may be an increase in cytosolic calcium, accompanying exercise. Many mixed syndromes mutants, including ∆KPQ, E1784K, 1795insD and Q1909R, are found in calcium-sensitive regions. Elevated cytosolic calcium attenuates gain-of-function properties in ∆KPQ, 1795insD and Q1909R, but not in E1784K. By contrast, elevated cytosolic calcium further exacerbates gain-of-function in E1784K by destabilizing slow inactivation. Action potential modelling, using a modified O'Hara Rudy model, suggests that elevated heart rate rescues action potential duration in ∆KPQ, 1795insD and Q1909R, but not in E1784K. Action potential simulations suggest that E1784K carriers have an increased intracellular sodium-to-calcium ratio under bradycardia and tachycardia conditions. Elevated cytosolic calcium, which is common during high heart rates, ameliorates or exacerbates the mixed syndrome phenotype depending on the genetic signature. ABSTRACT Inherited arrhythmias may arise from mutations in the gene for SCN5a, which encodes the cardiac voltage-gated sodium channel, NaV 1.5. Mutants in NaV 1.5 result in Brugada Syndrome (BrS1), Long-QT Syndrome (LQT3) or mixed syndromes (an overlap of BrS1/LQT3). Exercise is a potential arrhythmogenic trigger in mixed syndromes. We aimed to determine the effects of elevated cytosolic calcium, which is common during exercise, in mixed syndrome NaV 1.5 mutants. We used whole-cell patch clamp to assess the biophysical properties of NaV 1.5 wild-type (WT), ∆KPQ, E1784K, 1795insD and Q1909R mutants in human embryonic kidney 293 cells transiently transfected with the NaV 1.5 α subunit (WT or mutants), β1 subunit and enhanced green fluorescent protein. Voltage-dependence and kinetics were measured at cytosolic calcium levels of approximately 0, 500 and 2500 nm. In silico, action potential (AP) model simulations were performed using a modified O'Hara Rudy model. Elevated cytosolic calcium attenuates the late sodium current in ∆KPQ, 1795insD and Q1909R, but not in E1784K. Elevated cytosolic calcium restores steady-state slow inactivation (SSSI) to the WT-form in Q1909R, but depolarized SSSI in E1784K. Our AP simulations showed a frequency-dependent reduction of AP duration in ∆KPQ, 1795insD and Q1909R carriers. In E1784K, AP duration is relatively prolonged at both low and high heart rates, resulting in a sodium overload. Cellular perturbations during exercise may affect BrS1/LQT3 patients differently depending on their individual genetic signature. Thus, exercise may be therapeutic or may be an arrhythmogenic trigger in some SCN5a patients.
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Affiliation(s)
- Mena Abdelsayed
- Department of Biomedical Physiology and KinesiologySimon Fraser UniversityBurnabyCanada
| | - Alban‐Elouen Baruteau
- LIRYC Institute, Division of Pediatric Cardiology, Haut‐Lévèque HospitalBordeaux UniversityBordeauxFrance
| | - Karen Gibbs
- Division of CardiologyUniversity of British ColumbiaVancouverCanada
| | - Shubhayan Sanatani
- Department of Pediatrics, University of British ColumbiaBC Children's HospitalVancouverCanada
| | - Andrew D. Krahn
- Division of CardiologyUniversity of British ColumbiaVancouverCanada
| | - Vincent Probst
- L'institut du thorax, Inserm 1087Université de NantesNantesFrance
| | - Peter C. Ruben
- Department of Biomedical Physiology and KinesiologySimon Fraser UniversityBurnabyCanada
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44
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Hovey L, Fowler CA, Mahling R, Lin Z, Miller MS, Marx DC, Yoder JB, Kim EH, Tefft KM, Waite BC, Feldkamp MD, Yu L, Shea MA. Calcium triggers reversal of calmodulin on nested anti-parallel sites in the IQ motif of the neuronal voltage-dependent sodium channel Na V1.2. Biophys Chem 2017; 224:1-19. [PMID: 28343066 PMCID: PMC5503752 DOI: 10.1016/j.bpc.2017.02.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2017] [Revised: 02/23/2017] [Accepted: 02/23/2017] [Indexed: 01/26/2023]
Abstract
Several members of the voltage-gated sodium channel family are regulated by calmodulin (CaM) and ionic calcium. The neuronal voltage-gated sodium channel NaV1.2 contains binding sites for both apo (calcium-depleted) and calcium-saturated CaM. We have determined equilibrium dissociation constants for rat NaV1.2 IQ motif [IQRAYRRYLLK] binding to apo CaM (~3nM) and (Ca2+)4-CaM (~85nM), showing that apo CaM binding is favored by 30-fold. For both apo and (Ca2+)4-CaM, NMR demonstrated that NaV1.2 IQ motif peptide (NaV1.2IQp) exclusively made contacts with C-domain residues of CaM (CaMC). To understand how calcium triggers conformational change at the CaM-IQ interface, we determined a solution structure (2M5E.pdb) of (Ca2+)2-CaMC bound to NaV1.2IQp. The polarity of (Ca2+)2-CaMC relative to the IQ motif was opposite to that seen in apo CaMC-Nav1.2IQp (2KXW), revealing that CaMC recognizes nested, anti-parallel sites in Nav1.2IQp. Reversal of CaM may require transient release from the IQ motif during calcium binding, and facilitate a re-orientation of CaMN allowing interactions with non-IQ NaV1.2 residues or auxiliary regulatory proteins interacting in the vicinity of the IQ motif.
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Affiliation(s)
- Liam Hovey
- Department of Biochemistry, University of Iowa, 52242-1109 Iowa City, United States
| | - C Andrew Fowler
- NMR Facility, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, 52242-1109 Iowa City, United States
| | - Ryan Mahling
- Department of Biochemistry, University of Iowa, 52242-1109 Iowa City, United States
| | - Zesen Lin
- Department of Biochemistry, University of Iowa, 52242-1109 Iowa City, United States
| | - Mark Stephen Miller
- Department of Biochemistry, University of Iowa, 52242-1109 Iowa City, United States
| | - Dagan C Marx
- Department of Biochemistry, University of Iowa, 52242-1109 Iowa City, United States
| | - Jesse B Yoder
- Department of Biochemistry, University of Iowa, 52242-1109 Iowa City, United States
| | - Elaine H Kim
- Department of Biochemistry, University of Iowa, 52242-1109 Iowa City, United States
| | - Kristin M Tefft
- Department of Biochemistry, University of Iowa, 52242-1109 Iowa City, United States
| | - Brett C Waite
- Department of Biochemistry, University of Iowa, 52242-1109 Iowa City, United States
| | - Michael D Feldkamp
- Department of Biochemistry, University of Iowa, 52242-1109 Iowa City, United States
| | - Liping Yu
- NMR Facility, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, 52242-1109 Iowa City, United States
| | - Madeline A Shea
- Department of Biochemistry, University of Iowa, 52242-1109 Iowa City, United States.
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45
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Yan H, Wang C, Marx SO, Pitt GS. Calmodulin limits pathogenic Na+ channel persistent current. J Gen Physiol 2017; 149:277-293. [PMID: 28087622 PMCID: PMC5299624 DOI: 10.1085/jgp.201611721] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Revised: 12/13/2016] [Accepted: 12/19/2016] [Indexed: 01/29/2023] Open
Abstract
The molecular mechanisms controlling “persistent” current through voltage-gated Na+ channels are poorly understood. Yan et al. show that apocalmodulin binding to the intracellular C-terminal domain limits persistent Na+ flux and accelerates inactivation across the voltage-gated Na+ channel family. Increased “persistent” current, caused by delayed inactivation, through voltage-gated Na+ (NaV) channels leads to cardiac arrhythmias or epilepsy. The underlying molecular contributors to these inactivation defects are poorly understood. Here, we show that calmodulin (CaM) binding to multiple sites within NaV channel intracellular C-terminal domains (CTDs) limits persistent Na+ current and accelerates inactivation across the NaV family. Arrhythmia or epilepsy mutations located in NaV1.5 or NaV1.2 channel CTDs, respectively, reduce CaM binding either directly or by interfering with CTD–CTD interchannel interactions. Boosting the availability of CaM, thus shifting its binding equilibrium, restores wild-type (WT)–like inactivation in mutant NaV1.5 and NaV1.2 channels and likewise diminishes the comparatively large persistent Na+ current through WT NaV1.6, whose CTD displays relatively low CaM affinity. In cerebellar Purkinje neurons, in which NaV1.6 promotes a large physiological persistent Na+ current, increased CaM diminishes the persistent Na+ current, suggesting that the endogenous, comparatively weak affinity of NaV1.6 for apoCaM is important for physiological persistent current.
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Affiliation(s)
- Haidun Yan
- Ion Channel Research Unit, Duke University Medical Center, Durham, NC 27710
| | - Chaojian Wang
- Ion Channel Research Unit, Duke University Medical Center, Durham, NC 27710
| | - Steven O Marx
- Division of Cardiology, Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, NY 10032.,Department of Pharmacology, College of Physicians and Surgeons, Columbia University, New York, NY 10032
| | - Geoffrey S Pitt
- Ion Channel Research Unit, Duke University Medical Center, Durham, NC 27710
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46
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Kim DH, Lee SJ, Hahn SJ, Choi JS. Trifluoperazine blocks the human cardiac sodium channel, Na v1.5, independent of calmodulin. Biochem Biophys Res Commun 2016; 479:584-589. [PMID: 27666479 DOI: 10.1016/j.bbrc.2016.09.115] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 09/22/2016] [Indexed: 11/20/2022]
Abstract
Trifluoperazine is a phenothiazine derivative which is mainly used in the management of schizophrenia and also acts as a calmodulin inhibitor. We used the whole-cell patch-clamp technique to study the effects of trifluoperazine on human Nav1.5 (hNav1.5) currents expressed in HEK293 cells. The 50% inhibitory concentration of trifluoperazine was 15.5 ± 0.3 μM and the Hill coefficient was 2.7 ± 0.1. The effects of trifluoperazine on hNav1.5 were completely and repeatedly reversible after washout. Trifluoperazine caused depolarizing shifts in the activation and hyperpolarizing shifts in the steady-state inactivation of hNav1.5. Trifluoperazine also showed strong use-dependent inhibition of hNav1.5. The blockade of hNav1.5 currents by trifluoperazine was not affected by the whole cell dialysis of the calmodulin inhibitory peptide. Our results indicated that trifluoperazine blocks hNav1.5 current in concentration-, state- and use-dependent manners rather than via calmodulin inhibition.
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Affiliation(s)
- Dong-Hyun Kim
- College of Pharmacy, The Catholic University of Korea, Bucheon, Gyeonggi-do, 14662, South Korea
| | - Su-Jin Lee
- College of Pharmacy, The Catholic University of Korea, Bucheon, Gyeonggi-do, 14662, South Korea
| | - Sang June Hahn
- Department of Physiology, College of Medicine, The Catholic University of Korea, Seoul, 06591, South Korea
| | - Jin-Sung Choi
- College of Pharmacy, The Catholic University of Korea, Bucheon, Gyeonggi-do, 14662, South Korea.
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47
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Ben-Johny M, Dick IE, Sang L, Limpitikul WB, Kang PW, Niu J, Banerjee R, Yang W, Babich JS, Issa JB, Lee SR, Namkung H, Li J, Zhang M, Yang PS, Bazzazi H, Adams PJ, Joshi-Mukherjee R, Yue DN, Yue DT. Towards a Unified Theory of Calmodulin Regulation (Calmodulation) of Voltage-Gated Calcium and Sodium Channels. Curr Mol Pharmacol 2016; 8:188-205. [PMID: 25966688 DOI: 10.2174/1874467208666150507110359] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Revised: 01/29/2015] [Accepted: 04/20/2015] [Indexed: 12/13/2022]
Abstract
Voltage-gated Na and Ca(2+) channels represent two major ion channel families that enable myriad biological functions including the generation of action potentials and the coupling of electrical and chemical signaling in cells. Calmodulin regulation (calmodulation) of these ion channels comprises a vital feedback mechanism with distinct physiological implications. Though long-sought, a shared understanding of the channel families remained elusive for two decades as the functional manifestations and the structural underpinnings of this modulation often appeared to diverge. Here, we review recent advancements in the understanding of calmodulation of Ca(2+) and Na channels that suggest a remarkable similarity in their regulatory scheme. This interrelation between the two channel families now paves the way towards a unified mechanistic framework to understand vital calmodulin-dependent feedback and offers shared principles to approach related channelopathic diseases. An exciting era of synergistic study now looms.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - David T Yue
- Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Ross Building, Room 713, 720 Rutland Avenue, Baltimore, MD 21205, USA.
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48
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Pitt GS, Lee SY. Current view on regulation of voltage-gated sodium channels by calcium and auxiliary proteins. Protein Sci 2016; 25:1573-84. [PMID: 27262167 DOI: 10.1002/pro.2960] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2016] [Accepted: 05/31/2016] [Indexed: 11/09/2022]
Abstract
In cardiac and skeletal myocytes, and in most neurons, the opening of voltage-gated Na(+) channels (NaV channels) triggers action potentials, a process that is regulated via the interactions of the channels' intercellular C-termini with auxiliary proteins and/or Ca(2+) . The molecular and structural details for how Ca(2+) and/or auxiliary proteins modulate NaV channel function, however, have eluded a concise mechanistic explanation and details have been shrouded for the last decade behind controversy about whether Ca(2+) acts directly upon the NaV channel or through interacting proteins, such as the Ca(2+) binding protein calmodulin (CaM). Here, we review recent advances in defining the structure of NaV intracellular C-termini and associated proteins such as CaM or fibroblast growth factor homologous factors (FHFs) to reveal new insights into how Ca(2+) affects NaV function, and how altered Ca(2+) -dependent or FHF-mediated regulation of NaV channels is perturbed in various disease states through mutations that disrupt CaM or FHF interaction.
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Affiliation(s)
- Geoffrey S Pitt
- Cardiovascular Research Institute, Weill Cornell Medicine, New York, NY, 10065
| | - Seok-Yong Lee
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina, 27710
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49
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Jones BL, Smith SM. Calcium-Sensing Receptor: A Key Target for Extracellular Calcium Signaling in Neurons. Front Physiol 2016; 7:116. [PMID: 27065884 PMCID: PMC4811949 DOI: 10.3389/fphys.2016.00116] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 03/14/2016] [Indexed: 12/14/2022] Open
Abstract
Though both clinicians and scientists have long recognized the influence of extracellular calcium on the function of muscle and nervous tissue, recent insights reveal that the mechanisms allowing changes in extracellular calcium to alter cellular excitability have been incompletely understood. For many years the effects of calcium on neuronal signaling were explained only in terms of calcium entry through voltage-gated calcium channels and biophysical charge screening. More recently however, it has been recognized that the calcium-sensing receptor is prevalent in the nervous system and regulates synaptic transmission and neuronal activity via multiple signaling pathways. Here we review the multiplicity of mechanisms by which changes in extracellular calcium alter neuronal signaling and propose that multiple mechanisms are required to describe the full range of experimental observations.
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Affiliation(s)
- Brian L. Jones
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Oregon Health & Science UniversityPortland, OR, USA
| | - Stephen M. Smith
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Oregon Health & Science UniversityPortland, OR, USA
- Section of Pulmonary and Critical Care Medicine, VA Portland Health Care SystemPortland, OR, USA
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50
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Dick IE, Limpitikul WB, Niu J, Banerjee R, Issa JB, Ben-Johny M, Adams PJ, Kang PW, Lee SR, Sang L, Yang W, Babich J, Zhang M, Bazazzi H, Yue NC, Tomaselli GF. A rendezvous with the queen of ion channels: Three decades of ion channel research by David T Yue and his Calcium Signals Laboratory. Channels (Austin) 2015; 10:20-32. [PMID: 26176690 DOI: 10.1080/19336950.2015.1051272] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
David T. Yue was a renowned biophysicist who dedicated his life to the study of Ca(2+) signaling in cells. In the wake of his passing, we are left not only with a feeling of great loss, but with a tremendous and impactful body of work contributed by a remarkable man. David's research spanned the spectrum from atomic structure to organ systems, with a quantitative rigor aimed at understanding the fundamental mechanisms underlying biological function. Along the way he developed new tools and approaches, enabling not only his own research but that of his contemporaries and those who will come after him. While we cannot hope to replicate the eloquence and style we are accustomed to in David's writing, we nonetheless undertake a review of David's chosen field of study with a focus on many of his contributions to the calcium channel field.
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Affiliation(s)
- Ivy E Dick
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Worawan B Limpitikul
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Jacqueline Niu
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Rahul Banerjee
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - John B Issa
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Manu Ben-Johny
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Paul J Adams
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA.,b Kwantlen Polytechnic University ; Surrey , BC Canada
| | - Po Wei Kang
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Shin Rong Lee
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Lingjie Sang
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Wanjun Yang
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Jennifer Babich
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Manning Zhang
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Hojjat Bazazzi
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Nancy C Yue
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
| | - Gordon F Tomaselli
- a Calcium Signals Laboratory; Department of Biomedical Engineering ; Johns Hopkins University School of Medicine ; Baltimore , MD USA.,c Division of Cardiology; Department of Medicine ; Johns Hopkins University School of Medicine ; Baltimore , MD USA
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