Inhibition of the Cardiac Fibroblast-Enriched lncRNA <i>Meg3</i> Prevents Cardiac Fibrosis and Diastolic Dysfunction.

Abstract

Cardiac fibroblasts (CFs) drive extracellular matrix remodeling after pressure overload, leading to fibrosis and diastolic dysfunction. Recent studies described the role of long noncoding RNAs (lncRNAs) in cardiac pathologies. Nevertheless, detailed reports on lncRNAs regulating CF biology and describing their implication in cardiac remodeling are still missing. Here, we aimed at characterizing lncRNA expression in murine CFs after chronic pressure overload to identify CF-enriched lncRNAs and investigate their function and contribution to cardiac fibrosis and diastolic dysfunction. Global lncRNA profiling identified several dysregulated transcripts. Among them, the lncRNA maternally expressed gene 3 (<i>Meg3</i>) was found to be mostly expressed by CFs and to undergo transcriptional downregulation during late cardiac remodeling. In vitro, <i>Meg3</i> regulated the production of matrix metalloproteinase-2 (MMP-2). GapmeR-mediated silencing of <i>Meg3</i> in CFs resulted in the downregulation of <i>Mmp</i>-2 transcription, which, in turn, was dependent on P53 activity both in the absence and in the presence of transforming growth factor-β I. Chromatin immunoprecipitation showed that further induction of <i>Mmp</i>-2 expression by transforming growth factor-β I was blocked by <i>Meg3</i> silencing through the inhibition of P53 binding on the <i>Mmp-2</i> promoter. Consistently, inhibition of <i>Meg3</i> in vivo after transverse aortic constriction prevented cardiac MMP-2 induction, leading to decreased cardiac fibrosis and improved diastolic performance. Collectively, our findings uncover a critical role for <i>Meg3</i> in the regulation of MMP-2 production by CFs in vitro and in vivo, identifying a new player in the development of cardiac fibrosis and potential new target for the prevention of cardiac remodeling.