Vinculin-Mediated Cytoskeletal Remodeling Modulates Cardiac Morphology and Contractile Function During Ageing

Abstract

miR-448 in hearts of young dystrophic mice. The latter correlated with overexpression of the Ncf1 gene, encoding the NOX2 regulatory subunit p47phox. Specificity of Ncf1 targeting by miR-448 was confirmed by luciferase reporter assay. To study the effect of miR-448 silencing on molecular, cellular and functional properties of normal hearts, we intravenously injected wild type mice with LNA-NC and LNA-miR-448 inhibitors. qRT-PCR, western blotting, confocal imaging of ROS and intracellular Ca 2þ signals and echocardiography were employed. Acute inhibition of miR-448 resulted in an increase in Ncf1 expression as well as enhanced ROS production and augmented intracellular Ca 2þ signaling in isolated cardiomyocytes. In addition, prolong (over one month) inhibition of miR-448 led to the deterioration of cardiac functions and development of dilated cardiomyopathy and arrhythmia. Overall, WT mice with inhibited miR-448 mimicked many features of dystrophic cardiomyopathy. Our data suggest that downregulation of miR-448 relieves inhibition of translational initiation of Ncf1 in dystrophic cardiomyopathy. It results in an increase in Ncf1 expression and consequently in oxidative stress and enhanced Ca 2þ signaling in dystrophic heart well before cardiac dysfunction becomes evident.