Adriana Barana1, Marcos Matamoros1, Pablo Dolz-Gaitón1, Marta Pérez-Hernández1, Irene Amorós1, Mercedes Núñez1, Sandra Sacristán1, Álvaro Pedraz1, Ángel Pinto1, Francisco Fernández-Avilés1, Juan Tamargo1, Eva Delpón2, Ricardo Caballero1. 1. From the Department of Pharmacology (A.B., M.M., P.D.-G., M.P.-H., I.A., M.N., S.S., J.T., E.D., R.C.), and Instituto de Investigación Sanitaria Gregorio Marañón (A.B., M.M., P.D.-G., M.P.-H., I.A., M.N., S.S., J.T., E.D., R.C.), School of Medicine, Universidad Complutense de Madrid, Madrid, Spain; and Cardiology and Cardiovascular Surgery Services, Hospital General Universitario Gregorio Marañón, Madrid, Spain (Á.P., Á.P., F.F.-A.). 2. From the Department of Pharmacology (A.B., M.M., P.D.-G., M.P.-H., I.A., M.N., S.S., J.T., E.D., R.C.), and Instituto de Investigación Sanitaria Gregorio Marañón (A.B., M.M., P.D.-G., M.P.-H., I.A., M.N., S.S., J.T., E.D., R.C.), School of Medicine, Universidad Complutense de Madrid, Madrid, Spain; and Cardiology and Cardiovascular Surgery Services, Hospital General Universitario Gregorio Marañón, Madrid, Spain (Á.P., Á.P., F.F.-A.) edelpon@med.ucm.es.
Abstract
BACKGROUND: Atrial fibrillation is characterized by progressive atrial structural and electrical changes (atrial remodeling) that favor arrhythmia recurrence and maintenance. Reduction of L-type Ca(2+) current (I(Ca,L)) density is a hallmark of the electrical remodeling. Alterations in atrial microRNAs could contribute to the protein changes underlying atrial fibrillation-induced atrial electrical remodeling. This study was undertaken to compare miR-21 levels in isolated myocytes from atrial appendages obtained from patients in sinus rhythm and with chronic atrial fibrillation (CAF) and to determine whether L-type Ca(2+) channel subunits are targets for miR-21. METHODS AND RESULTS: Quantitative polymerase chain reaction analysis showed that miR-21 was expressed in human atrial myocytes from patients in sinus rhythm and that its expression was significantly greater in CAF myocytes. There was an inverse correlation between miR-21 and the mRNA of the α1c subunit of the calcium channel (CACNA1C) expression and I(Ca,L) density. Computational analyses predicted that CACNA1C and the mRNA of the β2 subunit of the calcium channel (CACNB2) could be potential targets for miR-21. Luciferase reporter assays demonstrated that miR-21 produced a concentration-dependent decrease in the luciferase activity in Chinese Hamster Ovary cells transfected with CACNA1C and CACNB2 3' untranslated region regions. miR-21 transfection in HL-1 cells produced changes in I(Ca,L) properties qualitatively similar to those produced by CAF (ie, a marked reduction of I(Ca,L) density and shift of the inactivation curves to more depolarized potentials). CONCLUSIONS: Our results demonstrated that CAF increases miR-21 expression in enzymatically isolated human atrial myocytes. Moreover, it decreases I(Ca,L) density by downregulating Ca(2+) channel subunits expression. These results suggested that this microRNA could participate in the CAF-induced I(Ca,L) downregulation and in the action potential duration shortening that maintains the arrhythmia.
BACKGROUND:Atrial fibrillation is characterized by progressive atrial structural and electrical changes (atrial remodeling) that favor arrhythmia recurrence and maintenance. Reduction of L-type Ca(2+) current (I(Ca,L)) density is a hallmark of the electrical remodeling. Alterations in atrial microRNAs could contribute to the protein changes underlying atrial fibrillation-induced atrial electrical remodeling. This study was undertaken to compare miR-21 levels in isolated myocytes from atrial appendages obtained from patients in sinus rhythm and with chronic atrial fibrillation (CAF) and to determine whether L-type Ca(2+) channel subunits are targets for miR-21. METHODS AND RESULTS: Quantitative polymerase chain reaction analysis showed that miR-21 was expressed in human atrial myocytes from patients in sinus rhythm and that its expression was significantly greater in CAF myocytes. There was an inverse correlation between miR-21 and the mRNA of the α1c subunit of the calcium channel (CACNA1C) expression and I(Ca,L) density. Computational analyses predicted that CACNA1C and the mRNA of the β2 subunit of the calcium channel (CACNB2) could be potential targets for miR-21. Luciferase reporter assays demonstrated that miR-21 produced a concentration-dependent decrease in the luciferase activity in Chinese Hamster Ovary cells transfected with CACNA1C and CACNB2 3' untranslated region regions. miR-21 transfection in HL-1 cells produced changes in I(Ca,L) properties qualitatively similar to those produced by CAF (ie, a marked reduction of I(Ca,L) density and shift of the inactivation curves to more depolarized potentials). CONCLUSIONS: Our results demonstrated that CAF increases miR-21 expression in enzymatically isolated human atrial myocytes. Moreover, it decreases I(Ca,L) density by downregulating Ca(2+) channel subunits expression. These results suggested that this microRNA could participate in the CAF-induced I(Ca,L) downregulation and in the action potential duration shortening that maintains the arrhythmia.
Authors: Ricardo Caballero; Raquel G Utrilla; Irene Amorós; Marcos Matamoros; Marta Pérez-Hernández; David Tinaquero; Silvia Alfayate; Paloma Nieto-Marín; Guadalupe Guerrero-Serna; Qing-Hua Liu; Roberto Ramos-Mondragón; Daniela Ponce-Balbuena; Todd Herron; Katherine F Campbell; David Filgueiras-Rama; Rafael Peinado; José L López-Sendón; José Jalife; Eva Delpón; Juan Tamargo Journal: Proc Natl Acad Sci U S A Date: 2017-01-03 Impact factor: 11.205