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

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: RNA Sequencing analysis of left ventricle samples.

背景：尽管现代心脏病治疗技术的进步已降低了病死率，但长期临床管理常伴随进行性心功能减退，最终表现为心力衰竭。核因子红细胞2相关因子2（Nuclear factor, erythroid 2 like 2，Nfe2l2，又名Nrf2）是一种转录调控因子，可在急性心肌损伤后为缺血心肌提供暂时性细胞保护作用；然而其持续激活却会反常诱发还原应激——这是一种新兴病理现象，以过度抗氧化功能与蛋白毒性重塑为特征。目前，慢性还原应激诱发心力衰竭的分子机制仍不明确。
方法：本研究采用心脏特异性表达组成型激活型Nrf2的转基因小鼠（caNrf2-Tg），按转基因表达水平分为低表达组（TgL）与高表达组（TgH），并对其开展整合式mRNA与小RNA（miRNA）测序。
结果与结论：本研究鉴定出多个受Nrf2剂量调控的miRNA位点，这些位点的上游区域含有推定的抗氧化反应元件（antioxidant response elements，AREs）。值得注意的是，Nrf2介导的miRNA调控显著富集于心脏特异性mRNA的转录后调控通路。综上，本研究证实Nrf2是心脏miRNA表达的强效调控因子，并为未来探究心肌氧化还原状态与病理生理之间的关联提供了全新的机制研究候选靶点。
整体实验设计：对左心室样本进行RNA测序分析。