title: Role of protein kinase C in metabolic regulation of the cardiac Na+channel.
abstract: The reduced form of nicotinamide adenine dinucleotide (NADH) increases in cardiomyopathy, activates protein kinase C (PKC), up-regulates mitochondrial reactive oxygen species (mitoROS), and down-regulates the cardiac Na+channel (NaV1.5).
  
  
  
  The purpose of this study was to determine how NADH signals down-regulation of NaV1.5.
  
  
  
  Isolated mouse cardiomyocytes were used for patch-clamp recording and for monitoring mitoROS with MitoSOX Red. HEK293 cells were used for transient transfections. HEK293 cells stably expressing human NaV1.5 were used for single channel recording, whole-cell patch-clamp recording, activity measurements of phospholipase C and phospholipase D (PLD), channel protein purification, and co-immunoprecipitation with PKC isoforms. HL-1 cells were used for mitochondria isolation.
  
  
  
  NADH enhanced PLD activity (1.6- ± 0.1-fold, P <.01) and activated PKCδ. Activated PKCδ translocated to mitochondria and up-regulated mitoROS (2.8- ± 0.3-fold, P <.01) by enhancing the activities of mitochondrial complexes I, II, and IV (1.1- to 1.5-fold, P <.01). PKCδ also interacted with NaV1.5 to down-regulate Na+current (INa). Reduction in INaby activated PKCδ was prevented by antioxidants and by mutating the known PKC phosphorylation site S1503. At the single channel level, the mechanism of current reduction by PKC and recovery by protein kinase A was a change in single channel conductance.
  
  
  
  NADH activated PKCδ by enhancing PLD activity. PKCδ modulated both mitoROS and NaV1.5. PKCδ elevated mitoROS by enhancing mitochondrial oxidative phosphorylation complex activities. PKCδ-mediated channel phosphorylation and mitoROS were both required to down-regulate NaV1.5 and alter single channel conductance.
authors.affiliation: Division of Cardiology, Department of Medicine, The Warren Alpert Medical School of Brown University, Lifespan Cardiovascular Institute, Providence, Rhode Island.
authors.forename: Man
authors.initials: M
authors.lastname: Liu
authors.affiliation: Division of Cardiology, Department of Medicine, The Warren Alpert Medical School of Brown University, Lifespan Cardiovascular Institute, Providence, Rhode Island.
authors.forename: Guangbin
authors.initials: G
authors.lastname: Shi
authors.affiliation: Division of Cardiology, Department of Medicine, The Warren Alpert Medical School of Brown University, Lifespan Cardiovascular Institute, Providence, Rhode Island; Graduate Institute of Pharmacology, National Taiwan University School of Medicine, Taipei City, Taiwan.
authors.forename: Kai-Chien
authors.initials: KC
authors.lastname: Yang
authors.affiliation: Section of Cardiology, University of Illinois at Chicago, Chicago, Illinois.
authors.forename: Lianzhi
authors.initials: L
authors.lastname: Gu
authors.affiliation: Department of Biomedical Sciences, Iowa Center for Advanced Neurotoxicology, Iowa State University, Ames, Iowa.
authors.forename: Anumantha G
authors.initials: AG
authors.lastname: Kanthasamy
authors.affiliation: Department of Biomedical Sciences, Iowa Center for Advanced Neurotoxicology, Iowa State University, Ames, Iowa.
authors.forename: Vellareddy
authors.initials: V
authors.lastname: Anantharam
authors.affiliation: Division of Cardiology, Department of Medicine, The Warren Alpert Medical School of Brown University, Lifespan Cardiovascular Institute, Providence, Rhode Island; Providence VA Medical Center, Providence, Rhode Island. Electronic address: samuel_dudley@brown.edu.
authors.forename: Samuel C
authors.initials: SC
authors.lastname: Dudley
mesh_terms: D000818:Animals; D001145:Arrhythmias, Cardiac / Q000378:metabolism; D002478:Cells, Cultured; D015536:Down-Regulation; D051379:Mice; D008929:Mitochondria, Heart / Q000502:physiology*; D032383:Myocytes, Cardiac / Q000502:physiology*; D009243:NAD / Q000378:metabolism; D062554:NAV1.5 Voltage-Gated Sodium Channel / Q000378:metabolism*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D062554:NAV1.5 Voltage-Gated Sodium Channel; D017382:Reactive Oxygen Species; D009243:NAD; C089212:protein kinase D; D011493:Protein Kinase C
keywords: Arrhythmia; Cardiomyopathy; Channel phosphorylation; Metabolism; Mitochondria; Nicotinamide adenine dinucleotide; Protein kinase Cδ