miR-499在急性心肌梗死早期辅助诊断及治疗中的作用及其分子机制探讨

寻找新的急性心肌梗死(AMI)特异而敏感的早期诊断方法及治疗手段，一直是医学工作者的奋斗目标。我们前期实验发现miR-499具有抑制细胞凋亡，保护心肌细胞的作用。本课题将通过对临床标本的检测和动物模型的建立，探讨miR-499是否可以作为AMI早期诊断及病程发展监控的生物标志；是否具有AMI临床分型特异性；miR-499是否对心肌细胞有保护作用；在AMI大鼠中，miR-499是否可以保护心脏功能，成为保护性标志物；阐明miR-499保护心肌细胞的分子机制，即JNK、ERK、p38等信号通路是否参与调节miR-499表达；构建在氧化应激损伤中，miR-499与其下游靶基因保护心肌细胞的调控网络。本课题的完成在一定程度上可明确miR-499作为AMI辅助诊断的生物标志物的可行性，为其在AMI诊断和治疗的潜在临床应用提供实验依据。

Myocardial infarction is a major cause of morbidity and mortality worldwide. The diagnosis of AMI is based on the "two of three" criteria, including typical chest symptoms, increase in the serum level of cardiac troponins T/I and typical ECG changes. Indeed, troponins T and I are sensitive and specific biomarkers of myocytes necrosis. However, it should be noted that it takes 2-4h for troponins to be released after the onset of AMI and the moderate elevation of troponins is common in chronic renal failure patients without significant myocardial damage. So, earlier biomarkers with both high sensitivity and specificity are urgently demanded. The diagnostic relevance of circulating microRNAs in AMI is a cutting-edge topic both for basic research and clinical implications. MiR-499 is a cardiac-abundant microRNA. We have previously found that miR-499 could protect neonatal rat cardiomyocytes against H2O2-induced apoptosis. We explore whether miR-499 could acts as an early diagnostic and monitoring biomarker; whether it possesses the property of the specific clinical classification and protects the cardiomyocytes. These works will be conducted in a rat AMI model and clinic AMI patients. Moreover, in AMI rats, we will prove that miR-499 could improve heart function by injecting recombinant miR-499 adenovirus into the caudal vein or borders of the infarct area and investigate whether miR-499 could be a protective biomarker. Finally, we will elucidate the molecular mechanisms that miR-499 protects cardiomyoctyes from apoptosis under pathological conditions. We have previously demonstrated that JNK signal rather than ERK and p38 is involved in the regulation of miR-499. Preliminary results also indicate that PACS2, PDCD4 and DYRK2 are the targets of miR-499. They co-participate to prevent the apoptosis of cardiomyocytes. Our final goal of this project is to construct a miR-499-centred the regulatory network in response to cardiac oxidative damage. The results will demonstrate the feasibility of miR-499 being the assisted diagnostic biomarker for AMI and provide the experimental basis for its applications in diagnosis and therapy of AMI in future.