title: Atrial Fibrillation-Mediated Upregulation of miR-30d Regulates Myocardial Electrical Remodeling of the G-Protein-Gated K(+) Channel, IK.ACh.
abstract: BACKGROUND
  Atrial fibrillation (AF) begets AF in part due to atrial remodeling, the molecular mechanisms of which have not been completely elucidated. This study was conducted to identify microRNA(s) responsible for electrical remodeling in AF.
  
  
  RESULTS
  The expression profiles of 1205 microRNAs, in cardiomyocytes from patients with persistent AF and from age-, gender-, and cardiac function-matched control patients with normal sinus rhythm, were examined by use of a microRNA microarray platform. Thirty-nine microRNAs differentially expressed in AF patients' atria were identified, including miR-30d, as a candidate responsible for ion channel remodeling by in silico analysis. MiR-30d was significantly upregulated in cardiomyocytes from AF patients, whereas the mRNA and protein levels ofCACNA1C/Cav1.2 andKCNJ3/Kir3.1, postulated targets of miR-30d, were markedly reduced.KCNJ3/Kir3.1 expression was downregulated by transfection of the miR-30 precursor, concomitant with a reduction of the acetylcholine-sensitive inward-rectifier K(+)current (IK.ACh).KCNJ3/Kir3.1 (but notCACNA1C/Cav1.2) expression was enhanced by the knockdown of miR-30d. The Ca(2+)ionophore, A23187, induced a dose-dependent upregulation of miR-30d, followed by the suppression ofKCNJ3mRNA expression. Blockade of protein kinase C signaling blunted the [Ca(2+)]i-dependent downregulation of Kir3.1 via miR-30d.
  
  
  CONCLUSIONS
  The downward remodeling ofIK.AChis attributed, at least in part, to deranged Ca(2+)handling, leading to the upregulation of miR-30d in human AF, revealing a novel post-transcriptional regulation ofIK.ACh. (Circ J 2016; 80: 1346-1355).
authors.affiliation: Department of Pathophysiology, Oita University School of Medicine.
authors.forename: Masaki
authors.initials: M
authors.lastname: Morishima
authors.forename: Eriko
authors.initials: E
authors.lastname: Iwata
authors.forename: Chisato
authors.initials: C
authors.lastname: Nakada
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Tsukamoto
authors.forename: Hiroki
authors.initials: H
authors.lastname: Takanari
authors.forename: Shinji
authors.initials: S
authors.lastname: Miyamoto
authors.forename: Masatsugu
authors.initials: M
authors.lastname: Moriyama
authors.forename: Katsushige
authors.initials: K
authors.lastname: Ono
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000503:physiopathology*; D016022:Case-Control Studies; D002478:Cells, Cultured; D015536:Down-Regulation; D005260:Female; D019204:GTP-Binding Proteins; D006801:Humans; D008297:Male; D035683:MicroRNAs / Q000502:physiology*; D008875:Middle Aged; D032383:Myocytes, Cardiac / Q000378:metabolism; D024661:Potassium Channels, Inwardly Rectifying / Q000378:metabolism*; D024642:Potassium Channels, Voltage-Gated / Q000378:metabolism; D015854:Up-Regulation
chemical_list: C546086:MIRN30b microRNA, human; D035683:MicroRNAs; D024661:Potassium Channels, Inwardly Rectifying; D024642:Potassium Channels, Voltage-Gated; D019204:GTP-Binding Proteins