Regulation of Cardiac Fibroblast Function by MicroRNAs

心脏纤维化是结构重塑的一个组成部分，其发生于多种心肺疾病，并且可能是内皮损伤的结果。它可以损害心室功能，增加心律失常的风险，并有助于心力衰竭的发展。心脏成纤维细胞是重要的治疗靶点，因为它们在应激反应中被激活，并在纤维化发展中发挥关键作用。开发特异性靶向成纤维细胞的疗法的努力仍处于早期阶段。与传统的药物靶点相比，microRNAs（miRNAs）提供了新的机制可能性。到目前为止，对它们在心脏成纤维细胞中的作用知之甚少。我已经确定了成年大鼠心室成纤维细胞中的miRNA表达模式及其在体外成纤维细胞活化过程中的动态调节。miRNA-1是一种富含肌肉的miRNA，目前已在肌细胞中进行了广泛研究，它在心脏成纤维细胞中表达，并在激活后显著下调。我的初步数据还显示了成纤维细胞增殖、转化和几个预测的miRNA-1靶点的蛋白表达的miRNA-1依赖性负调控，这些靶点参与细胞周期调控和纤维化发展。本研究的长期目标是更好地了解miRNAs在生理和病理生理条件下心脏成纤维细胞中的功能作用和作用机制。具体目标是：i）鉴定在体外和体内成纤维细胞活化时表达改变的miRNA，并基于其表达谱和靶预测选择候选miRNA用于进一步研究; 2）使用功能获得和功能丧失方法描述miRNA-1和其他miRNA在成人心脏成纤维细胞中的功能效应和作用机制; 3）确定成纤维细胞限制性miRNA操作对体内心脏纤维化发展的预防和/或逆转的作用。该项目将为心脏成纤维细胞中的miRNAs提供新的和全面的见解。这些发现将为未来的资助申请提供一个平台，旨在充分描述成纤维细胞限制性miRNA在体内的作用，这可能提供新的治疗策略。

Cardiac fibrosis is an integral feature of structural remodeling that occurs in response to a variety of cardiopulmonary diseases and can be a consequence of endothelial injury. It can impair ventricular function, increase the risk for arrhythmias and contribute to heart failure development. Cardiac fibroblasts are important therapeutic targets because they become activated in response to stress and play a key role in fibrosis development. Efforts to develop therapies that specifically target fibroblasts are still at an early stage. Compared to traditional drug targets, microRNAs (miRNAs) offer novel mechanistic possibilities. So far, little is known about their role in cardiac fibroblasts. I have determined the miRNA expression pattern in adult rat ventricular fibroblasts and their dynamic regulation during fibroblast activation in vitro. MiRNA-1, a muscle-enriched miRNA that has so far been extensively studied in myocytes, is shown to be expressed in cardiac fibroblasts and markedly down-regulated upon activation. My preliminary data also show miRNA-ldependent negative regulation of fibroblast proliferation, transformation and protein expression of several predicted miRNA-1 targets that are involved in cell cycle regulation and fibrosis development. The long-term goal of my research is to gain a better understanding of the functional role and mechanisms of action of miRNAs in cardiac fibroblasts under physiological and pathophysiological conditions. The Specific Aims are: i) To identify miRNAs that are changed in their expression upon fibroblast activation in vitro and in vivo and to select candidate miRNAs for further investigation based on their expression profile and target predictions; 2) To delineate functional effects and mechanisms of action of miRNA-1 and other miRNAs in adult cardiac fibroblasts using gain- and loss-of-function approaches; 3) To determine the effects of fibroblast-restricted miRNA manipulation on prevention and/or reversal of cardiac fibrosis development in vivo. This project will provide novel and comprehensive insights into miRNAs in cardiac fibroblasts. The findings will provide a platform for future grant applications that will aim to fully delineate the effects of fibroblast-restricted miRNA manipulation in vivo, which may provide new therapeutic strategies.