scholarly journals GPD1L links redox state to cardiac excitability by PKC-dependent phosphorylation of the sodium channel SCN5A

2009 ◽  
Vol 297 (4) ◽  
pp. H1446-H1452 ◽  
Author(s):  
Carmen R. Valdivia ◽  
Kazuo Ueda ◽  
Michael J. Ackerman ◽  
Jonathan C. Makielski
Keyword(s):  
Sodium Channel ◽  
Sodium Current ◽  
Expression System ◽  
Sudden Cardiac Arrest ◽  
Sudden Infant ◽  
Cell Physiology ◽  
Glycerol Phosphate ◽  
Enzymatic Function ◽  
Cardiac Sodium Channel ◽  
Glycerol Phosphate Dehydrogenase

The SCN5A-encoded cardiac sodium channel underlies excitability in the heart, and dysfunction of sodium current ( INa) can cause fatal ventricular arrhythmia in maladies such as long QT syndrome, Brugada syndrome (BrS), and sudden infant death syndrome (SIDS). The gene GPD1L encodes the glycerol phosphate dehydrogenase 1-like protein with homology to glycerol phosphate dehydrogenase (GPD1), but the function for this enzyme is unknown. Mutations in GPD1L have been associated with BrS and SIDS and decrease INa through an unknown mechanism. Using a heterologous expression system, we show that GPD1L associated with SCN5A and that the BrS- and SIDS-related mutations in GPD1L caused a loss of enzymatic function resulting in glycerol-3-phosphate PKC-dependent phosphorylation of SCN5A at serine 1503 (S1503) through a GPD1L-dependent pathway. The direct phosphorylation of S1503 markedly decreased INa. These results show a function for GPD1L in cell physiology and a mechanism linking mutations in GPD1L to sudden cardiac arrest. Because the enzymatic step catalyzed by GPD1L depends upon nicotinamide adenine dinucleotide, this GPD1L pathway links the metabolic state of the cell to INa and excitability and may be important more generally in cardiac ischemia and heart failure.

Abstract 1503: Knockdown of Mog1 Expression Reduces Sodium Currents by Reducing the Trafficking of Cardiac Sodium Channel Na V 1.5 to the Cell Membrane

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Susmita Chakrabarti ◽  
Sandro Yong ◽  
Shin Yoo ◽  
Ling Wu ◽  
Qing Kenneth Wang
Keyword(s):  
Sodium Channel ◽  
Ventricular Myocytes ◽  
Sodium Current ◽  
Expression System ◽  
Heart Association ◽  
Hek293 Cells ◽  
Similar Reduction ◽  
Mammalian Expression ◽  
Ventricular Cells ◽  
Cardiac Sodium Channel

The cardiac sodium channel (Na v 1.5) plays a significant role in cardiac physiology and leads to cardiac arrhythmias and sudden death when mutated. Modulation of Na v 1.5 activity can also arise from changes to accessory subunits or proteins. Our laboratory has recently reported that MOG1, a small protein that is highly conserved from yeast to humans, is a co-factor of Na v 1.5. Increased MOG1 expression has been shown to increase Na v 1.5 current density. In adult mouse ventricular myocytes, these two proteins were found to be co-localized at the intercalated discs. Here, we further characterize the regulatory role of MOG1 using the RNA interference technique. Sodium current was recorded in voltage-clamp mode from a holding potential of −100 mV and activated to −20 mV. In 3-day old mouse neonatal ventricular cells transfected with siRNA against mouse MOG1 decreased sodium current densities (pA/pF) compared to control or scramble siRNA treated cells (−10.2±3.3, n=11 vs. −165±16, n=20 or −117.9±11.7, n=11). A similar reduction in sodium current was observed in mammalian expression system consisting of HEK293 cells stably expressing human Na v 1.5, by transfecting siRNAs against either human or mouse MOG1 (−41.7±8.3, n=7 or, −82.6±9.6, n=7 vs. −130.6±11.5, n=7; −111.5±8.5, n=7, respectively). Immunocytochemistry revealed that the expression of MOG1 and Na v 1.5 were decreased in both HEK and neonatal cells when compared to scramble siRNAs or control groups. These results show that MOG1 is an essential co-factor for Na v 1.5 by way of a channel trafficking. Such interactions between MOG1 and Na v 1.5 suggest that early localization of MOG1 on the membrane of neonatal cardiomyocytes may be necessary for proper localization and the distribution of Na v 1.5 during cardiac development. This research has received full or partial funding support from the American Heart Association, AHA National Center.

Abstract 15925: Localization of Nav1.5 at the Intercellular Junctions Resolved by Diffraction-Unlimited Microscopy in Three Dimensions and by Correlative Light-Electron Microscopy

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Alejandra Leo-Macias ◽  
Esperanza Agullo-Pascual ◽  
Eli Rothenberg ◽  
Mario Delmar
Keyword(s):  
Electron Microscopy ◽  
Sodium Channel ◽  
Ventricular Myocytes ◽  
Sodium Current ◽  
Intercellular Junctions ◽  
Three Dimensions ◽  
Macromolecular Complex ◽  
Adult Heart ◽  
Mechanical Coupling ◽  
Cardiac Sodium Channel

Sodium current amplitude, kinetics and regulation depend on the properties of the pore-forming protein (mostly NaV1.5 in adult heart) and on the specific molecular partners with which the channel protein associates. The composition of the voltage-gated sodium channel macromolecular complex is location-specific; yet, the exact position of NaV1.5 in the subcellular landscape of the intercalated disc (ID), remains unclear. We implemented diffraction unlimited microscopy (direct stochastic optical reconstruction microscopy, or “dSTORM”) to localize the pore-forming subunit of the cardiac sodium channel NaV1.5 with a resolution of 20nm on the XY plane. In isolated adult ventricular myocytes, NaV1.5 was found in distinct semi-circular clusters. When the entire population of clusters within a 500 nm window from the ID was considered (more than 350 individual clusters analyzed), 75% of them localized to N-cadherin rich sites. NaV1.5-distal clusters were found at an average 313±15 nm from the cell end. Introducing an astigmatic lens in the light path allowed us to solve cluster location in three dimensions, at resolutions of 20 nm in XY and 40 nm in the z plane. Three-dimensional images confirmed the preferential localization at or near N-cadherin plaques, and further suggested that NaV1.5 arrives to the membrane via N-cadherin-anchored paths, most likely microtubules. In additional experiments, we developed a novel approach to correlate the image of NaV1.5 clusters by dSTORM with the cellular ultrastructure as resolved by electron microscopy on the same sample. This “correlative light-electron microscopy” method confirmed the preference of NaV1.5 clusters at sites of mechanical coupling. Overall, we provide the first ultrastructural description of NaV1.5 at the cardiac ID and its relation with the major electron-dense domains of the adult heart. Our data support a model by which microtubule-mediated delivery of NaV1.5 anchors at N-cadherin-rich sites, likely “mixed junctions” also containing desmosomal molecules (such as plakophilin-2; see Cerrone et al; Circulation 129:1092-1103, 2014) and connexin43. These findings have major implications to the understanding of sodium current disruption in diseases affecting the integrity of the ID.

scholarly journals Cardiac Sodium Channel Dysfunction in Sudden Infant Death Syndrome

Circulation ◽  
2007 ◽  
Vol 115 (3) ◽  
pp. 368-376 ◽  
Author(s):  
Dao W. Wang ◽  
Reshma R. Desai ◽  
Lia Crotti ◽  
Marianne Arnestad ◽  
Roberto Insolia ◽  
...  
Keyword(s):  
Sodium Channel ◽  
Sudden Infant Death Syndrome ◽  
Infant Death ◽  
Sudden Infant Death ◽  
Sudden Infant ◽  
Cardiac Sodium Channel

scholarly journals Distinct CASK domains control cardiac sodium channel membrane expression and focal adhesion anchoring

2019 ◽  
Author(s):  
Adeline Beuriot ◽  
Catherine A. Eichel ◽  
Gilles Dilanian ◽  
Florent Louault ◽  
Dario Melgari ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Sodium Channel ◽  
Sodium Current ◽  
Adaptor Proteins ◽  
Functional Domain ◽  
Membrane Expression ◽  
Glycoprotein Complex ◽  
Cardiac Sodium Channel ◽  
Dystrophin Glycoprotein Complex ◽  
Dystrophin Glycoprotein

ABSTRACTMembrane-associated guanylate kinase (MAGUK) proteins function as adaptor proteins to mediate the recruitment and scaffolding of ion channels in the plasma membrane in various cell types. In the heart, the protein CASK (Calcium/CAlmodulin-dependent Serine protein Kinase) negatively regulates the main cardiac sodium channel, NaV1.5, which carries the sodium current (INa) by preventing its anterograde trafficking. CASK is also a new member of the dystrophin-glycoprotein complex, and like syntrophin, binds to the C-terminal domain of the channel. Here we show that both L27B and GUK domains are required for the negative regulatory effect of CASK on INa and NaV1.5 surface expression and that the HOOK domain is essential for interaction with the cell adhesion dystrophin-glycoprotein complex. Thus, the multi-modular structure of CASK potentially provides the ability to control channel delivery at adhesion points in cardiomyocyte.SUMMARYSequential functional domain deletion approach identifies three critical domains of CASK in cardiomyocytes. CASK binds the cell adhesion dystrophin-glycoprotein complex through HOOK domain and inhibits NaV1.5 channel membrane expression by impeding trafficking through L27B and GUK domains.

Ranolazine may be the Best and Safest Pharmacologic Therapy For Congestive Heart Failure, And Safe, Effective For Ventricular And Atrial Arrhythmias

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Gary L Murray
Keyword(s):  
Heart Failure ◽  
Congestive Heart Failure ◽  
Sodium Channel ◽  
Sodium Current ◽  
Left Ventricular ◽  
Left Ventricular Ejection ◽  
Pharmacologic Therapy ◽  
Ventricular Ejection Fraction ◽  
Late Sodium Current ◽  
Cardiac Sodium Channel

Background:Ranolazine (RAN) reduces cardiac sodium channel 1.5’s late sodium current(INaL ) in congestive heart failure (CHF), reducing myocardial calcium overload, potentially improving left ventricular ejection fraction(LVEF) and reducing arrhyth-mogenic after potentials. RAN blocks neuronal sodium channel 1.7(Nav 1.7), potentially altering parasympathetic and sympathetic (P&S) activity. RAN also selectively blocks inactivated atrial Nav 1.8, as well as ventricular IKr and ICaL ,affecting atrial and ventric-ular arrhythmias.

Effects of Halothane and Isoflurane on Fast and Slow Inactivation of Human Heart hH1a Sodium Channels

1999 ◽  
Vol 90 (6) ◽  
pp. 1671-1683. ◽  
Author(s):  
Anna Stadnicka ◽  
Wai-Meng Kwok ◽  
Hali A. Hartmann ◽  
Zeljko J. Bosnjak
Keyword(s):  
Steady State ◽  
Heterologous Expression ◽  
Sodium Channel ◽  
Sodium Channels ◽  
Human Heart ◽  
Sodium Current ◽  
Volatile Anesthetic ◽  
Slow Inactivation ◽  
Fast Inactivation ◽  
Cardiac Sodium Channel

Background Cloning and heterologous expression of ion channels allow biophysical and molecular studies of the mechanisms of volatile anesthetic interactions with human heart sodium channels. Volatile anesthetics may influence the development of arrhythmias arising from cardiac sodium channel dysfunction. For that reason, understanding the mechanisms of interactions between these anesthetics and cardiac sodium channels is important. This study evaluated the mechanisms of volatile anesthetic actions on the cloned human cardiac sodium channel (hH1a) alpha subunit. Methods Inward sodium currents were recorded from human embryonic kidney (HEK293) cells stably expressing hH1a channels. The effects of halothane and isoflurane on current and channel properties were evaluated using the whole cell voltage-clamp technique. Results Halothane at 0.47 and 1.1 mM and isoflurane at 0.54 and 1.13 mM suppressed the sodium current in a dose- and voltage-dependent manner. Steady state activation was not affected, but current decay was accelerated. The voltage dependence of steady state fast and slow inactivations was shifted toward more hyperpolarized potentials. The slope factor of slow but not fast inactivation curves was reduced significantly. Halothane increased the time constant of recovery from fast inactivation. The recovery from slow inactivation was not affected significantly by either anesthetic. Conclusions In a heterologous expression system, halothane and isoflurane interact with the hH1a channels and suppress the sodium current. The mechanisms involve acceleration of the transition from the open to the inactivated state, stabilization of the fast and slow inactivated states, and prolongation of the inactivated state by delayed recovery from the fast inactivated to the resting state.

scholarly journals Heritable arrhythmia syndromes associated with abnormal cardiac sodium channel function: ionic and non-ionic mechanisms

2020 ◽  
Vol 116 (9) ◽  
pp. 1557-1570 ◽  
Author(s):  
Mathilde R Rivaud ◽  
Mario Delmar ◽  
Carol Ann Remme
Keyword(s):  
Action Potential ◽  
Sodium Channel ◽  
Sodium Current ◽  
Alternative View ◽  
Sodium Influx ◽  
Disease Spectrum ◽  
Cardiac Sodium Channel ◽  
Ionic Mechanisms ◽  
Ion Conducting ◽  
Ionic Effects

Abstract The cardiac sodium channel NaV1.5, encoded by the SCN5A gene, is responsible for the fast upstroke of the action potential. Mutations in SCN5A may cause sodium channel dysfunction by decreasing peak sodium current, which slows conduction and facilitates reentry-based arrhythmias, and by enhancing late sodium current, which prolongs the action potential and sets the stage for early afterdepolarization and arrhythmias. Yet, some NaV1.5-related disorders, in particular structural abnormalities, cannot be directly or solely explained on the basis of defective NaV1.5 expression or biophysics. An emerging concept that may explain the large disease spectrum associated with SCN5A mutations centres around the multifunctionality of the NaV1.5 complex. In this alternative view, alterations in NaV1.5 affect processes that are independent of its canonical ion-conducting role. We here propose a novel classification of NaV1.5 (dys)function, categorized into (i) direct ionic effects of sodium influx through NaV1.5 on membrane potential and consequent action potential generation, (ii) indirect ionic effects of sodium influx on intracellular homeostasis and signalling, and (iii) non-ionic effects of NaV1.5, independent of sodium influx, through interactions with macromolecular complexes within the different microdomains of the cardiomyocyte. These indirect ionic and non-ionic processes may, acting alone or in concert, contribute significantly to arrhythmogenesis. Hence, further exploration of these multifunctional effects of NaV1.5 is essential for the development of novel preventive and therapeutic strategies.

C2C12 skeletal muscle cells adopt cardiac-like sodium current properties in a cardiac cell environment

2007 ◽  
Vol 292 (1) ◽  
pp. H439-H450 ◽  
Author(s):  
Eva Zebedin ◽  
Markus Mille ◽  
Maria Speiser ◽  
Touran Zarrabi ◽  
Walter Sandtner ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Sodium Channel ◽  
Sodium Current ◽  
Muscle Cells ◽  
Skeletal Muscle Cells ◽  
Cardiac Cell ◽  
Sodium Currents ◽  
Current Function ◽  
Electrophysiological Properties ◽  
Cardiac Sodium Channel

Intracardiac transplantation of undifferentiated skeletal muscle cells (myoblasts) has emerged as a promising therapy for myocardial infarct repair and is already undergoing clinical trials. The fact that cells originating from skeletal muscle have different electrophysiological properties than cardiomyocytes, however, may considerably limit the success of this therapy and, in addition, cause side effects. Indeed, a major problem observed after myoblast transplantation is the occurrence of ventricular arrhythmias. The most often transient nature of these arrhythmias may suggest that, once transplanted into cardiac tissue, skeletal muscle cells adopt more cardiac-like electrophysiological properties. To test whether a cardiac cell environment can indeed modify electrophysiological parameters of skeletal muscle cells, we treated mouse C2C12 myocytes with medium preconditioned by primary cardiocytes and compared their functional sodium current properties with those of control cells. We found this treatment to significantly alter the activation and inactivation properties of sodium currents from “skeletal muscle” to more “cardiac”-like ones. Sodium currents of cardiac-conditioned cells showed a reduced sensitivity to block by tetrodotoxin. These findings and reverse transcription PCR experiments suggest that an upregulation of the expression of the cardiac sodium channel isoform Nav1.5 versus the skeletal muscle isoform Nav1.4 is responsible for the observed changes in sodium current function. We conclude that cardiomyocytes alter sodium channel isoform expression of skeletal muscle cells via a paracrine mechanism. Thereby, skeletal muscle cells with more cardiac-like sodium current properties are generated.

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