Loss of microRNA-106b-25 cluster promotes atrial fibrillation by enhancing ryanodine receptor type-2 expression and calcium release.
BACKGROUND
Enhanced sarcoplasmic reticulum Ca(2+)-leak via ryanodine receptor type-2 (RyR2) contributes to the pathogenesis of atrial fibrillation (AF). Recent studies have shown that the level of RyR2 protein is elevated in atria of patients with paroxysmal AF, suggesting that microRNA-mediated post-transcriptional regulation of RyR2 might be an underlying mechanism. Bioinformatic analysis suggests that miR-106b and miR-93, members of the miR-106b-25 cluster, could bind to RyR2-3'-untranslated region and suppress its translation. Thus, we tested the hypothesis that loss of the miR-106b-25 cluster promotes AF via enhanced RyR2-mediated sarcoplasmic reticulum Ca(2+)-leak.


RESULTS
Quantitative real-time polymerase chain reaction showed that the levels of mature miR-106b, miR-93, and miR-25 were lower in atria of patients with paroxysmal AF when compared with patients in sinus rhythm. In vitro assay showed that miR-93 reduced RyR2-3'-untranslated region luciferase activity. Total RyR2 protein in atrial tissue of miR-106b-25(-/-) mice was increased by 42% when compared with wild-type littermates but still maintained a normal subcellular distribution. Ca(2+)-spark frequency and total sarcoplasmic reticulum Ca(2+)-leak were increased in atrial myocytes of miR-106b-25(-/-) mice. Telemetry ECG recordings revealed that miR-106b-25(-/-) mice exhibited more frequent atrial ectopy and were also more susceptible to pacing-induced AF than wild-type littermates. Increased sarcoplasmic reticulum Ca(2+)-release and AF susceptibility in miR-106b-25(-/-) mice were abolished by the RyR2 blocker K201.


CONCLUSIONS
These results suggest that miR-106b-25 cluster-mediated post-transcriptional regulation of RyR2 is a potential molecular mechanism involved in paroxysmal AF pathogenesis. As such, the miR-106b-25 cluster could be a novel gene-therapy target in AF associated with enhanced RyR2 expression.
From the Cardiovascular Research Institute (D.Y.C., D.L.B., K.M.A., J.F.M., X.H.T.W., N.L.), Department of Molecular Physiology and Biophysics (D.Y.C., N.K., D.L.B., K.M.A., J.R.N., J.F.M., X.H.T.W., N.L.) Interdepartmental Program in Translational Biology and Molecular Medicine (D.Y.C., D.L.B.), Department of Medicine (Cardiology) (X.H.T.W.), Baylor College of Medicine, Houston, TX; Texas Heart Institute, Houston (J.F.M.); Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen, Essen, Germany (N.V., D.D.); and Department of Thoracic and Cardiovascular Surgery, University Hospital, Essen, Germany (H.J.).
David Y
DY
Chiang
From the Cardiovascular Research Institute (D.Y.C., D.L.B., K.M.A., J.F.M., X.H.T.W., N.L.), Department of Molecular Physiology and Biophysics (D.Y.C., N.K., D.L.B., K.M.A., J.R.N., J.F.M., X.H.T.W., N.L.) Interdepartmental Program in Translational Biology and Molecular Medicine (D.Y.C., D.L.B.), Department of Medicine (Cardiology) (X.H.T.W.), Baylor College of Medicine, Houston, TX; Texas Heart Institute, Houston (J.F.M.); Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen, Essen, Germany (N.V., D.D.); and Department of Thoracic and Cardiovascular Surgery, University Hospital, Essen, Germany (H.J.).
Natee
N
Kongchan
From the Cardiovascular Research Institute (D.Y.C., D.L.B., K.M.A., J.F.M., X.H.T.W., N.L.), Department of Molecular Physiology and Biophysics (D.Y.C., N.K., D.L.B., K.M.A., J.R.N., J.F.M., X.H.T.W., N.L.) Interdepartmental Program in Translational Biology and Molecular Medicine (D.Y.C., D.L.B.), Department of Medicine (Cardiology) (X.H.T.W.), Baylor College of Medicine, Houston, TX; Texas Heart Institute, Houston (J.F.M.); Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen, Essen, Germany (N.V., D.D.); and Department of Thoracic and Cardiovascular Surgery, University Hospital, Essen, Germany (H.J.).
David L
DL
Beavers
From the Cardiovascular Research Institute (D.Y.C., D.L.B., K.M.A., J.F.M., X.H.T.W., N.L.), Department of Molecular Physiology and Biophysics (D.Y.C., N.K., D.L.B., K.M.A., J.R.N., J.F.M., X.H.T.W., N.L.) Interdepartmental Program in Translational Biology and Molecular Medicine (D.Y.C., D.L.B.), Department of Medicine (Cardiology) (X.H.T.W.), Baylor College of Medicine, Houston, TX; Texas Heart Institute, Houston (J.F.M.); Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen, Essen, Germany (N.V., D.D.); and Department of Thoracic and Cardiovascular Surgery, University Hospital, Essen, Germany (H.J.).
Katherina M
KM
Alsina
From the Cardiovascular Research Institute (D.Y.C., D.L.B., K.M.A., J.F.M., X.H.T.W., N.L.), Department of Molecular Physiology and Biophysics (D.Y.C., N.K., D.L.B., K.M.A., J.R.N., J.F.M., X.H.T.W., N.L.) Interdepartmental Program in Translational Biology and Molecular Medicine (D.Y.C., D.L.B.), Department of Medicine (Cardiology) (X.H.T.W.), Baylor College of Medicine, Houston, TX; Texas Heart Institute, Houston (J.F.M.); Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen, Essen, Germany (N.V., D.D.); and Department of Thoracic and Cardiovascular Surgery, University Hospital, Essen, Germany (H.J.).
Niels
N
Voigt
From the Cardiovascular Research Institute (D.Y.C., D.L.B., K.M.A., J.F.M., X.H.T.W., N.L.), Department of Molecular Physiology and Biophysics (D.Y.C., N.K., D.L.B., K.M.A., J.R.N., J.F.M., X.H.T.W., N.L.) Interdepartmental Program in Translational Biology and Molecular Medicine (D.Y.C., D.L.B.), Department of Medicine (Cardiology) (X.H.T.W.), Baylor College of Medicine, Houston, TX; Texas Heart Institute, Houston (J.F.M.); Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen, Essen, Germany (N.V., D.D.); and Department of Thoracic and Cardiovascular Surgery, University Hospital, Essen, Germany (H.J.).
Joel R
JR
Neilson
From the Cardiovascular Research Institute (D.Y.C., D.L.B., K.M.A., J.F.M., X.H.T.W., N.L.), Department of Molecular Physiology and Biophysics (D.Y.C., N.K., D.L.B., K.M.A., J.R.N., J.F.M., X.H.T.W., N.L.) Interdepartmental Program in Translational Biology and Molecular Medicine (D.Y.C., D.L.B.), Department of Medicine (Cardiology) (X.H.T.W.), Baylor College of Medicine, Houston, TX; Texas Heart Institute, Houston (J.F.M.); Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen, Essen, Germany (N.V., D.D.); and Department of Thoracic and Cardiovascular Surgery, University Hospital, Essen, Germany (H.J.).
Heinz
H
Jakob
From the Cardiovascular Research Institute (D.Y.C., D.L.B., K.M.A., J.F.M., X.H.T.W., N.L.), Department of Molecular Physiology and Biophysics (D.Y.C., N.K., D.L.B., K.M.A., J.R.N., J.F.M., X.H.T.W., N.L.) Interdepartmental Program in Translational Biology and Molecular Medicine (D.Y.C., D.L.B.), Department of Medicine (Cardiology) (X.H.T.W.), Baylor College of Medicine, Houston, TX; Texas Heart Institute, Houston (J.F.M.); Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen, Essen, Germany (N.V., D.D.); and Department of Thoracic and Cardiovascular Surgery, University Hospital, Essen, Germany (H.J.).
James F
JF
Martin
From the Cardiovascular Research Institute (D.Y.C., D.L.B., K.M.A., J.F.M., X.H.T.W., N.L.), Department of Molecular Physiology and Biophysics (D.Y.C., N.K., D.L.B., K.M.A., J.R.N., J.F.M., X.H.T.W., N.L.) Interdepartmental Program in Translational Biology and Molecular Medicine (D.Y.C., D.L.B.), Department of Medicine (Cardiology) (X.H.T.W.), Baylor College of Medicine, Houston, TX; Texas Heart Institute, Houston (J.F.M.); Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen, Essen, Germany (N.V., D.D.); and Department of Thoracic and Cardiovascular Surgery, University Hospital, Essen, Germany (H.J.).
Dobromir
D
Dobrev
From the Cardiovascular Research Institute (D.Y.C., D.L.B., K.M.A., J.F.M., X.H.T.W., N.L.), Department of Molecular Physiology and Biophysics (D.Y.C., N.K., D.L.B., K.M.A., J.R.N., J.F.M., X.H.T.W., N.L.) Interdepartmental Program in Translational Biology and Molecular Medicine (D.Y.C., D.L.B.), Department of Medicine (Cardiology) (X.H.T.W.), Baylor College of Medicine, Houston, TX; Texas Heart Institute, Houston (J.F.M.); Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen, Essen, Germany (N.V., D.D.); and Department of Thoracic and Cardiovascular Surgery, University Hospital, Essen, Germany (H.J.).
Xander H T
XH
Wehrens
From the Cardiovascular Research Institute (D.Y.C., D.L.B., K.M.A., J.F.M., X.H.T.W., N.L.), Department of Molecular Physiology and Biophysics (D.Y.C., N.K., D.L.B., K.M.A., J.R.N., J.F.M., X.H.T.W., N.L.) Interdepartmental Program in Translational Biology and Molecular Medicine (D.Y.C., D.L.B.), Department of Medicine (Cardiology) (X.H.T.W.), Baylor College of Medicine, Houston, TX; Texas Heart Institute, Houston (J.F.M.); Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen, Essen, Germany (N.V., D.D.); and Department of Thoracic and Cardiovascular Surgery, University Hospital, Essen, Germany (H.J.). nal@bcm.edu.
Na
N
Li
D020413:3' Untranslated Regions; D000200:Action Potentials; D000818:Animals; D001281:Atrial Fibrillation / Q000235:genetics / Q000378:metabolism* / Q000503:physiopathology; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling; D016022:Case-Control Studies; D004195:Disease Models, Animal; D015536:Down-Regulation; D055785:Gene Knockdown Techniques; D006801:Humans; D018345:Mice, Knockout; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D019837:Ryanodine Receptor Calcium Release Channel / Q000235:genetics / Q000378:metabolism*; D012519:Sarcoplasmic Reticulum / Q000378:metabolism*; D013997:Time Factors; D014158:Transcription, Genetic; D015854:Up-Regulation
D020413:3' Untranslated Regions; C542541:MIRN106 microRNA, human; D035683:MicroRNAs; C543896:Mirn106 microRNA, mouse; D019837:Ryanodine Receptor Calcium Release Channel; C000592748:ryanodine receptor 2. mouse; D002118:Calcium
atrial fibrillation; microRNA; ryanodine receptor calcium release channel