Role of miR-574 driver and passenger strands in cardiac hypertrophy

项目总结： 心血管疾病(CVD)是世界范围内发病率和死亡率的主要原因。更好 了解心血管疾病的病理机制将有助于预防和治疗心血管疾病。 治疗性干预。心血管疾病的主要病因之一是心脏基因表达失调。 通过转录因子(TF)和microRNAs(MiRNAs)。MiRNAs是小的非编码RNA 参与基因表达调控。TFS通常是较差的小分子药物靶点。 然而，miRNAs可以作为独特的治疗剂，因为它们可以靶向 相同的病理途径。大多数前体miRNAs(前miRNAs)被处理以生成 一种活跃的驱动链miRNA；互补的乘客链通常被降解。 有趣的是，前miR-574产生了两条功能链-miR-574-5P和miR-574-3P。我们发现 MiR-574的两条链在保护心脏免受心肌肥厚方面发挥协同作用。我们 结果表明，miR-574-5p在慢性心力衰竭组织中与正常心脏相比被诱导。 我们发现miR-574-5p在肥厚和缺血应激下表达上调，并沉默 三种促肥大因子心肌细胞增强因子-2(Mef2a/2c/2d)和 防止心肌细胞(CM)肥大。MiR-574-5P模拟物在小鼠体内的转染 心肌细胞对异丙肾上腺素(β-肾上腺素能激动剂)诱导的细胞保护作用 肥大和缺氧-血清饥饿诱导的细胞死亡。MIR-574基因敲除小鼠表现出 晚期心肌肥厚表型与纤维化增加和心肌肥大相关， 与慢性注射ISO后野生型小鼠进行比较。我们还展示了乘客链 MiR-574-3P与miR-574-5P共上调，但被缺氧激活的磷酸化hnRNP捕获 L(多相核糖核蛋白L)。MIR-574-3P由CM通过外切体和 以成纤维细胞为靶点，减少纤维化。我们的研究目标是解决以下基本问题 在心脏系统中使用miR-574-5P/3P作为原型分子的miRNA生物学(区分 规章制度、机制多样性和驾驶员与乘客的功能关系 链)，并通过开发针对转铁蛋白的基于miRNA的疗法来治疗心衰。我们的中央 假说是：在肥厚和缺血应激下的CM中，司机的差异调节 链miR-574-5p和乘客链miR-574-3p整合了心脏基因表达和 调节病理性心肌肥厚和重塑。我们将通过以下方式验证这一假设 追求两个目标。目标1将检验miR-574-5p调节Mef2表达的假设 TFS和其他心脏基因通过miRISC，从而调节心肌肥厚和重塑。 Aim 2将验证在心肌缺血中通过特定的转录因子促进miR-574转录的假设 并激活P-hnRNP L对miR-574-3p的捕获，随后胞外体分泌和 细胞间通信。

Project Summary: Cardiovascular disease (CVD) is the leading cause of morbidity and mortality worldwide. Better understanding of the pathological mechanisms underlying CVD will improve preventive and therapeutic interventions. One major etiology of CVD is dysregulation of cardiac gene expression by transcription factors (TFs) and microRNAs (miRNAs). miRNAs are small non-coding RNAs involved in gene expression regulation. TFs are usually poor small-molecule drug targets. However, miRNAs can act as unique therapeutic agents because they can target multiple TFs in the same pathological pathway. Most precursor miRNAs (pre-miRNAs) are processed to generate an active driver strand miRNA; the complementary passenger strand is usually degraded. Intriguingly, pre-miR-574 produces two functional strands—miR-574-5p and miR-574-3p. We found that both strands of miR-574 play a synergistic role to protect hearts from cardiac hypertrophy. We showed that miR-574-5p was induced in chronic human heart failure tissues versus normal hearts. We found that miR-574-5p is up-regulated under hypertrophic and ischemic stress and silences the expression of three pro-hypertrophy TFs myocyte enhancer factor–2 factors (Mef2a/2c/2d) and prevents cardiomyocyte (CM) hypertrophy. Transfection of miR-574-5p mimics in mouse cardiomyocytes (CM) protects the cells from isoproterenol (ISO, a β-adrenergic agonist)-induced hypertrophy and hypoxia-serum starvation-induced cell death. miR-574 knockout mice exhibit an advanced cardiac hypertrophy phenotype associated with increased fibrosis and enlarged CM, compared to wild-type mice after chronic ISO injection. We also showed that the passenger strand miR-574-3p is co-upregulated with miR-574-5p but captured by hypoxia-activated phospho-hnRNP L (heterogeneous nuclear ribonucleoprotein L). miR-574-3p is secreted from CM via exosomes and targets fibroblasts to reduce fibrosis. Our research goal is to address fundamental questions in miRNA biology using miR-574-5p/3p as archetypal molecules in the cardiac system (differential regulation, mechanistic diversity, and functional relationship between driver and passenger strands), and to treat HF by developing miRNA-based therapeutics that target TFs. Our central hypothesis is: In CM under hypertrophic and ischemic stress, differential regulation of the driver strand miR-574-5p and passenger strand miR-574-3p integrate cardiac gene expression and modulate pathological cardiac hypertrophy and remodelling. We will test this hypothesis by pursuing two aims. Aim 1 will test the hypothesis that miR-574-5p regulates the expression of Mef2 TFs and other cardiac genes via miRISC, thereby modulates cardiac hypertrophy and remodelling. Aim 2 will test the hypothesis that in CM ischemia promotes miR-574 transcription via specific TFs and activates capture of miR-574-3p by P-hnRNP L followed by exosome secretion and intercellular communication.