Heart Failure and MEF2 Transcriptome Dynamics in Response to β-Blockers.

Myocyte Enhancer Factor 2 (MEF2) mediates cardiac remodelling in heart failure (HF) and is also a target of β-adrenergic signalling, a front-line treatment for HF. We identified global gene transcription networks involved in HF with and without β-blocker treatment. Experimental HF by transverse aortic constriction (TAC) in a MEF2 "sensor" mouse model (6 weeks) was followed by four weeks of β-blockade with Atenolol (AT) or Solvent (Sol) treatment. Transcriptome analysis (RNA-seq) from left ventricular RNA samples and MEF2A depleted cardiomyocytes was performed. AT treatment resulted in an overall improvement in cardiac function of TAC mice and repression of MEF2 activity. RNA-seq identified 65 differentially expressed genes (DEGs) due to TAC treatment with enriched GO clusters including the inflammatory system, cell migration and apoptosis. These genes were mapped against DEGs in cardiomyocytes in which MEF2A expression was suppressed. Of the 65 TAC mediated DEGs, AT reversed the expression of 28 mRNAs. Rarres2 was identified as a novel MEF2 target gene that is upregulated with TAC in vivo and isoproterenol treatment in vitro which may have implications in cardiomyocyte apoptosis and hypertrophy. These studies identify a cohort of genes with vast potential for disease diagnosis and therapeutic intervention in heart failure.