Heart failure (HF) is the ultimate outcome of many cardiovascular diseases. Re-expression of fetal genes in the adult heart contributes to development of HF. Two mechanisms involved in the control of gene expression are epigenetics and microRNAs (miRs). We propose a project on epigenetic and miR-mediated mechanisms leading to HF. Epigenetics refers to heritable modification of DNA and histones that does not modify the genetic code. Depending on the type of modification and on the site affected, these chemical changes up- or down-regulate transcription of specific genes. Despite it being a major player in gene regulation, epigenetics has been only partly investigated in HF. miRs are regulatory RNAs that target mRNAs for inhibition. Dysregulation of the cardiac miR signature occurs in HF. miR expression may itself be under epigenetic control, constituting a miR-epigenetic regulatory network. To our knowledge, this possibility has not been studied yet. Our specific hypothesis is that the profile of DNA/histone methylation and the cross-talk between epigenetic enzymes and miRs have fundamental roles in defining the characteristics of cells during cardiac development and that the dysregulation of these processes determines the deleterious nature of the stressed hearts gene programme. We will test this first through a genome-wide study of DNA/histone methylation to generate maps of the main methylation modifications occurring in the genome of cardiac cells treated with a pro-hypertrophy regulator and of a HF model. We will then investigate the role of epigenetic enzymes deemed important in HF, through the generation and study of knockout mice models. Finally, we will test the possible therapeutic potential of modulating epigenetic genes. We hope to further understand the pathological mechanisms leading to HF and to generate data instrumental to the development of diagnostic and therapeutic strategies for this disease.