title: Regulation of SCN5A by microRNAs: miR-219 modulates SCN5A transcript expression and the effects of flecainide intoxication in mice.
abstract: BACKGROUND
  The human cardiac action potential in atrial and ventricular cells is initiated by a fast-activating, fast-inactivating sodium current generated by the SCN5A/Nav1.5 channel in association with its β1/SCN1B subunit. The role of Nav1.5 in the etiology of many cardiac diseases strongly suggests that proper regulation of cell biology and function of the channel is critical for normal cardiac function. Hence, numerous recent studies have focused on the regulatory mechanisms of Nav1.5 biosynthetic and degradation processes as well as its subcellular localization.
  
  
  OBJECTIVE
  The purpose of this study was to investigate the role of microRNAs in the Scn5a/Nav1.5 posttranscriptional regulation.
  
  
  METHODS
  Quantitative polymerase chain reaction, immunohistochemical and electrophysiological measurements of distinct microRNA gain-of-function experiments in cardiomyocytes for the assessment of Scn5a expression.
  
  
  RESULTS
  Functional studies of HL-1 cardiomyocytes and luciferase assays in fibroblasts demonstrate that Scn5a is directly (miR-98, miR-106, miR-200, and miR-219) and indirectly (miR-125 and miR-153) regulated by multiple microRNAs displaying distinct time-dependent profiles. Cotransfection experiments demonstrated that miR-219 and miR-200 have independent opposite effects on Scn5a expression modulation. Of all the microRNAs studied, only miR-219 increases Scn5a expression levels, leading to altered contraction rhythm of HL-1 cardiomyocytes. Electrophysiological analyses in HL-1 cells revealed that miR-219 increases the sodium current. In vivo administration of miR-219 does not alter normal cardiac rhythm, but abolishes some of the effects of flecainide intoxication in mice, particularly QRS prolongation.
  
  
  CONCLUSIONS
  This study demonstrates the involvement of multiple microRNAs in the regulation of Scn5a. Particularly, miR-219 increases Scn5a/Nav1.5 transcript and protein expression. Our data suggest that microRNAs, such as miR-219, constitute a promising therapeutical tool to treat sodium cardiac arrhythmias.
authors.affiliation: Department of Experimental Biology, University of Jaén, Jáen, Spain; Biochemistry and Molecular Biology Laboratory, Faculty of Pharmacy, University of Monastir, Monastir, Tunisia.
authors.forename: Houria
authors.initials: H
authors.lastname: Daimi
authors.affiliation: Department of Experimental Biology, University of Jaén, Jáen, Spain.
authors.forename: Estefania
authors.initials: E
authors.lastname: Lozano-Velasco
authors.affiliation: Biochemistry and Molecular Biology Laboratory, Faculty of Pharmacy, University of Monastir, Monastir, Tunisia.
authors.forename: Amel
authors.initials: A
authors.lastname: Haj Khelil
authors.affiliation: Biochemistry and Molecular Biology Laboratory, Faculty of Pharmacy, University of Monastir, Monastir, Tunisia.
authors.forename: Jemni B E
authors.initials: JB
authors.lastname: Chibani
authors.affiliation: Department of Pharmacology, Faculty of Medicine, Complutense University of Madrid, Madrid, Spain.
authors.forename: Adriana
authors.initials: A
authors.lastname: Barana
authors.affiliation: Department of Pharmacology, Faculty of Medicine, Complutense University of Madrid, Madrid, Spain.
authors.forename: Irene
authors.initials: I
authors.lastname: Amorós
authors.affiliation: Department of Pharmacology, Faculty of Medicine, Complutense University of Madrid, Madrid, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: González de la Fuente
authors.affiliation: Department of Pharmacology, Faculty of Medicine, Complutense University of Madrid, Madrid, Spain.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Caballero
authors.affiliation: Department of Experimental Biology, University of Jaén, Jáen, Spain.
authors.forename: Amelia
authors.initials: A
authors.lastname: Aranega
authors.affiliation: Department of Experimental Biology, University of Jaén, Jáen, Spain. Electronic address: dfranco@ujaen.es.
authors.forename: Diego
authors.initials: D
authors.lastname: Franco
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004562:Electrocardiography; D004594:Electrophysiology; D005424:Flecainide / Q000506:poisoning*; D007150:Immunohistochemistry; D051379:Mice; D035683:MicroRNAs / Q000502:physiology*; D032383:Myocytes, Cardiac; D062554:NAV1.5 Voltage-Gated Sodium Channel / Q000032:analysis*; D016133:Polymerase Chain Reaction; D012323:RNA Processing, Post-Transcriptional / Q000502:physiology; D014162:Transfection
chemical_list: D035683:MicroRNAs; D062554:NAV1.5 Voltage-Gated Sodium Channel; C568321:Scn5a protein, mouse; D005424:Flecainide
keywords: MicroRNAs; Posttranscriptional regulation; SCN5A; miR-200; miR-219