microRNA-26a在压力超负荷心力衰竭中的作用和机制研究

MicroRNAs (miRNAs) comprise a broad class of small non-coding RNAs that control expression of complementary target messenger RNAs. Growing evidences indicates that miRNA expression is altered in human heart failure, and specific miRNAs has been linked to cardiac development and function. Our previous studies have demonstrated that overexpression of miR-26a regulates the expression of glycogen synthase kinase 3-beta (GSK-3β) in cardiaomyocyte and cardiac fibroblasts in vitro, which has impacts on cardiac hypertrophy and collagen synthesis. But effects and mechanisms of miR-26a on heart failure still need further investigation. Our study will focus on the role of miR-26a in rat and mouse models of transverse abdominal aorta constriction (TAAC)-induced pressure overload-heart failure. We first constructed miR-26a overexpression models in vivo by infecting TAAC animals with miRNA oligonucleotid intravenous injecting or with an adenoviral vector containing miR-26a precursor sequence intra-cardiomyocyte injecting under ultrasound guiding. The global cardiac structure and function will be analyzed by small animal echocardiography instrument and histomorphology. Our study also further investigates the mechanisms of miR-26a on heart failure. The expression levels of miR-26a and the target genes of miR-26a, GSK3β and Enhancer of Zeste homolog 2 (EZH2), are detected synchronously. Furthermore, the regulating effects of GSK3β/EZH2 on cardiac myocyte size, apoptosis and interstitial fibrosis will be investigated too. Our study will disclose a new therapeutic target for heart failure following pressure overload.

MicroRNAs (miRNAs)参与心力衰竭(HF)的发病，调控miRNAs的表达可能影响HF的进程。我们前期研究结果显示过表达miR-26a能抑制原代心肌细胞肥大和成纤维细胞胶原合成，且与糖原合成酶激酶3β(GSK3β)有关，但miR-26a对HF过程的影响以及具体调控机制仍有待进一步完善。本研究是基于前期研究的动物体内实验，拟采用腹主动脉缩窄(TAAC)建立压力超负荷大鼠和小鼠HF模型，应用超声引导腺病毒载体心肌注射和miRNA寡核苷酸静脉注射两种方法在动物心肌组织中过表达miR-26a，用心脏彩超仪和组织形态学方法观察miR-26a对HF的影响，并探讨miR-26a两个靶基因GSK3β和Enhancer of Zeste homolog 2（EZH2）与心肌细胞大小、细胞凋亡、心脏间质纤维化之间的关系。研究结果对阐明miR-26a在HF调控中的作用和机制以及临床应用有重要意义。

本项目主要探讨miR-26a对心脏肥大/心力衰竭的调控作用及其分子机制。课题组如期开展项目研究，完成了计划中的前期实验内容，阐明了miR-26在心力衰竭动物模型和心肌肥大细胞模型中的表达规律，证实miR-26可通过靶向作用于糖原合成酶激酶3β(GSK3β)调控心肌细胞肥大，发表了相关的论文。接着按照原计划设计构建了过表达miR-26a的重组腺病毒载体，并在体外培养的心肌细胞中成功进行了感染实验，构建了压力超负荷心力衰竭大鼠模型，但经反复实验未能成功在心肌组织中过表达miR-26a。课题组对原计划作了调整，做了如下尝试并获得了相应的结果：1.证实了miR-26a对体外培养的心肌成纤维细胞胶原合成的调控作用和机制；2.证实了miR-199a-5p对心肌细胞肥大的调控作用；3.证实了miR-29a对心肌细胞凋亡的调控作用。共发表了1篇SCI论文和3篇中文核心期刊论文。这些结果进一步证明了miRNA在心脏肥大/心力衰竭发病过程中的显著作用。