1天龄小鼠切除15%心尖组织后21天可完全再生（成年小鼠则无此能力），是研究心肌再生机制的理想模型。我们前期发现：新生小鼠心肌损伤后能够激活OSMR/gp130信号，进而促进心肌细胞增殖。本项目计划：①构建心肌细胞条件敲除OSMR（和gp130）基因工程小鼠，1天龄进行心肌损伤，分析OSMR/gp130在心肌再生中的作用。②OSM诱导原代心肌细胞增殖和gp130激活，RNA测序筛选gp130下游信号；应用抑制剂和siRNA阻断候选信号通路，功能学水平确定gp130下游哪些信号参与调控心肌细胞增殖。③针对候选通路的关键蛋白，co-IP确定其是否与gp130相互作用；应用ChIP-Seq解析相关转录调控机制。④构建心肌细胞特异激活gp130小鼠，成年小鼠制备心梗，功能学水平探讨激活gp130是否能有效促进受损心肌修复并改善心功能。本项目将为理解新生小鼠再生提供新机制，为心肌损伤修复提供新靶点。

The hearts of 1-day-old mice can regenerate completely with cardiomyocyte proliferation, after myocardial infarction or apical resection (15% ventricular myocardium resected), over 21 days. In contrast, adult heart cannot regenerate after myocardial injury. Therefore, neonatal mouse heart is an ideal model to study the molecular mechanism of mammalian cardiac regeneration for its robust capacity of fully regeneration after cardiac injury. Our previous study found that injury-induced activation of OSMR/gp130 is essential to promote cardiomyocyte proliferation. To explore the underlying mechanism and clinical perspective of OSMR/gp130 in myocardial regeneration, we intend to carry out following experiments: ① Conditionally knocking out OSMR or gp130 in cardiomyocytes and performing myocardial injury operation, myocardial infarction or apical resection, respectively, in 1-day-old mice. Harvesting hearts at 21 day-post-injury and analyzing the myocardial regenerative capacity to evaluate the role of OSMR/gp130 in myocardial regeneration. ② Extracting total RNA from primary neonatal mouse cardiomyocytes administrated by OSM, which can promote cardiomyocyte proliferation and induce OSMR/gp130 activation, and employing RNA sequencing to explore the downstream signaling pathways of OSMR/gp130. Candidate pathways will be blocked by inhibitors (or siRNAs) in primary neonatal mouse cardiomyocytes with OSM treatment to identify the pathways controlling cardiomyocyte proliferation functionally. ③ To confirm the role of the candidate downstream pathway protein of OSMR/gp130 signaling in OSM-induced cardiomyocyte proliferation, we will investigate the interaction between these candidate proteins and gp130 by co-IP and explore the transcriptional regulation mechanisms using ChIP-Seq and RNA sequencing. ④ To clarify whether gp130 activation can promote myocardial repair and improve cardiac function in adult mice, we will conditional activate gp130 in cardiomyocytes genetically and ligate left descending artery leading to myocardial infarction. Myocardial repair and the recovery of cardiac function will be evaluated via Masson staining and echocardiography. Collectively, we will elucidate the role of OSMR/gp130 signaling in myocardial regeneration and cardiomyocyte proliferation, which will reveal a new insight of neonatal heart regeneration and provide a potential target for myocardial repair.