title: Downregulation of connexin43 by microRNA-130a in cardiomyocytes results in cardiac arrhythmias.
abstract: MicroRNAs (miRNAs) are now recognized as critical regulators of diverse physiological and pathological processes; however, studies of miRNAs and arrhythmogenesis remain sparse. Connexin43 (Cx43), a major cardiac gap junction protein, has elicited great interest in its role in arrhythmias. Additionally, Cx43 was a potential target for miR-130a as predicted by several computational algorithms. This study investigates the effect of miR-130a overexpression in the adult heart and its effect on cardiac rhythm. Using a cardiac-specific inducible system, transgenic mice demonstrated both atrial and ventricular arrhythmias. We performed ventricular-programmed electrical stimulation and found that the αMHC-miR130a mice developed sustained ventricular tachycardia beginning 6weeks after overexpression. Western blot analysis demonstrated a steady decline in Cx43 after 2weeks of overexpression with over a 90% reduction in Cx43 levels by 10weeks. Immunofluorescent staining confirmed a near complete loss of Cx43 throughout the heart. To validate Cx43 as a direct target of miR-130a, we performed in vitro target assays in 3T3 fibroblasts and HL-1 cardiomyocytes, both known to endogenously express miR-130a. Using a luciferase reporter fused to the 3'UTR of Cx43, we found a 52.9% reduction in luciferase activity in 3T3 cells (p<0.0001) and a 47.6% reduction in HL-1 cells (p=0.0056) compared to controls. Addition of an antisense miR-130a inhibitor resulted in a loss of inhibitory activity of the Cx43 3'UTR reporter. We have identified an unappreciated role for miR-130a as a direct regulator of Cx43. Overexpression of miR-130a may contribute importantly to gap junction remodeling and to the pathogenesis of atrial and ventricular arrhythmias.
authors.affiliation: University of Chicago, Institute for Cardiovascular Research, 5841 S. Maryland Ave, MC 6080, Chicago, IL 60637, USA.
authors.forename: Appledene
authors.initials: A
authors.lastname: Osbourne
authors.affiliation: University of Chicago, Institute for Cardiovascular Research, 5841 S. Maryland Ave, MC 6080, Chicago, IL 60637, USA.
authors.forename: Tyler
authors.initials: T
authors.lastname: Calway
authors.affiliation: University of Chicago, Institute for Cardiovascular Research, 5841 S. Maryland Ave, MC 6080, Chicago, IL 60637, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Broman
authors.affiliation: University of Chicago, Institute for Cardiovascular Research, 5841 S. Maryland Ave, MC 6080, Chicago, IL 60637, USA.
authors.forename: Saoirse
authors.initials: S
authors.lastname: McSharry
authors.affiliation: University of Chicago, Institute for Cardiovascular Research, 5841 S. Maryland Ave, MC 6080, Chicago, IL 60637, USA.
authors.forename: Judy
authors.initials: J
authors.lastname: Earley
authors.affiliation: University of Chicago, Institute for Cardiovascular Research, 5841 S. Maryland Ave, MC 6080, Chicago, IL 60637, USA. Electronic address: gkim1@medicine.bsd.uchicago.edu.
authors.forename: Gene H
authors.initials: GH
authors.lastname: Kim
mesh_terms: D020413:3' Untranslated Regions; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D018031:Connexin 43 / Q000235:genetics* / Q000378:metabolism; D005260:Female; D017629:Gap Junctions / Q000378:metabolism / Q000473:pathology; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D006325:Heart Atria / Q000378:metabolism* / Q000473:pathology; D006352:Heart Ventricles / Q000378:metabolism* / Q000473:pathology; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D051379:Mice; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000378:metabolism* / Q000473:pathology; D018995:Myosin Heavy Chains / Q000235:genetics / Q000378:metabolism; D041681:NIH 3T3 Cells; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D020413:3' Untranslated Regions; D018031:Connexin 43; C554019:MIRN130 microRNA, human; D035683:MicroRNAs; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins; D008156:Luciferases; D018995:Myosin Heavy Chains
keywords: Atrial arrhythmia; Connexin43; MicroRNA; Ventricular arrhythmia