Cardiac ReductomiRs: Identification of Novel Nrf2-Dependent microRNAs as Post-Transcriptional Regulators of Myocardial Gene Expression [miRNA]

Background: Although modern advances in the treatment of heart disease have reduced mortality rates, long-term medical management is often associated with a progressive loss of function that manifests as heart failure. Nuclear factor, erythroid 2 like 2 (Nfe2l2, a.k.a. Nrf2) is a transcriptional regulator that provides the ischemic heart with transient cytoprotection following acute myocardial insult; however, its sustained activation paradoxically causes reductive stress, an emerging pathological phenomenon characterized by excessive antioxidant function and proteotoxic remodeling. Yet, the molecular mechanism by which chronic reductive stress produces heart failure remains elusive. Methods: Cardiac-specific constitutively active Nrf2 transgenic (caNrf2-Tg) mice expressing the transgene at low (TgL) and high (TgH) levels were employed in integrative mRNA and small RNA (miRNA) sequencing. Results and Conclusion: Here, we reveal several Nrf2 dose-responsive miRNA loci harboring putative upstream antioxidant response elements (AREs). Intriguingly, Nrf2-mediated miRNA responses were distinctly enriched for post-transcriptional regulation of cardiac-specific mRNAs. Altogether, these data reveal Nrf2 as a potent regulator of cardiac miRNA expression and provide novel candidates for future mechanistic investigation into the relationship between myocardial redox status and pathophysiology. Overall design: microRNA sequencing analysis of left ventricle samples.