Abstract MP144: Identification of Epigenetic Regulators of Cardiac Hypertrophy by an Epigenome-wide Association Study in Mice

Abstract

We previously reported a study of heart failure in a large cohort of inbred mouse strains, the Hybrid Mouse Diversity Panel (HMDP), treated with the beta-adrenergic agonist isoproterenol, which identified over 30 genome-wide significant loci for heart failure-related traits. Our approach combined systems-level tools with the benefits of a curated model organism population to identify genetic variations that drive heart failure. We now expand this study into the epigenome. Recent research has demonstrated that DNA methylation affects the progression of cardiovascular phenotypes. This research suggests that DNA methylation may serve as an additional marker of genes involved in heart failure-associated phenotypes. Using Reduced Representational Bisulfite Sequencing, we profiled left ventricular tissue samples from 88 strains of the HMDP both before and after isoproterenol challenge (30 mg/kg/day for 21 days). We identified approximately 168,000 CpGs that vary across the panel and associated them with a set of phenotypes in both control and treated animals using the epigenome-wide association study (EWAS) algorithm MACAU. 179 significant associations were recovered at an FDR of 5%, including loci that associated pre-treatment CpG methylation with 19 different post-treatment phenotypes. By combining these EWAS loci with information from the Wellcome Trust Mouse Genomes Resource and prior work done in the heart failure HMDP, we identify several high-confidence candidate genes, including Coro1a , a gene whose pre-treatment promoter methylation status predicts post-treatment wall thickening and Eprs , which predicts right ventricular weight post-treatment. Mospd3 , a gene that was associated with right ventricular weight post-treatment in both EWAS and GWAS analyses was studied further using neonatal rat ventricular myocytes. This in vitro work demonstrates that Mospd3 knockdown results in reduced cellular hypertrophy and changes to hypertrophy-related gene expression. Further analysis of the EWAS loci using in vitro and in vivo techniques will likely validate additional genes and elucidate how DNA methylation acts to regulate pathways underlying heart failure.