Regulation of Cardiac Fibroblast Function by MicroRNAs

心脏纤维化是各种心肺疾病引起的结构性重构的一个重要特征，也可能是血管内皮损伤的结果。它会损害心脏功能，增加心律失常的风险，并导致心力衰竭的发展。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，并在纤维化的发展中发挥关键作用。开发专门针对成纤维细胞的治疗方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，人们对它们在心脏成纤维细胞中的作用知之甚少。我在体外测定了成年大鼠心室成纤维细胞miRNA的表达模式及其在成纤维细胞激活过程中的动态调节。MiRNA-1是一种在心肌细胞中被广泛研究的富含肌肉的miRNA，已被证明在心脏成纤维细胞中表达，并在激活时显著下调。我的初步数据还显示，miRNA依赖于对成纤维细胞增殖、转化和蛋白表达的负调控，几个预测的miRNA-1靶点参与了细胞周期调节和纤维化的发展。本研究的长期目标是更好地了解在生理和病理生理条件下miRNAs在心脏成纤维细胞中的功能作用和作用机制。其具体目的是：i)鉴定在体外和体内成纤维细胞激活时其表达发生变化的miRNAs，并根据其表达谱和靶点预测选择候选miRNAs用于进一步研究；2)利用功能获得和功能丧失的方法描述miRNA-1和其他miRNAs在成人心脏成纤维细胞中的功能作用和作用机制；3)确定成纤维细胞限制性miRNA操作在预防和/或逆转体内心脏纤维化发展方面的作用。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。这一发现将为未来的拨款申请提供一个平台，旨在全面描述体内成纤维细胞限制的miRNA操作的影响，这可能会提供新的治疗策略。

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.