严重烧伤后心肌保护的内源性新机制：Notch-CARL-MnSOD/NHE1通路？

Cardiomyocyte apoptosis is the key cellular cause of myocardial damage postburn. Our previous study has revealed that Notch could coordinately increase MnSOD and decrease NHE1, and thus inhibits apoptosis induced by burn injury. Up to now, the detailed mechanism how Notch-MnSOD/NHE1 regulatory axis occurs is largely unknown, while detailed elucidation of the mechanism would certainly shed light on the cardiac prevention in the context of burn injury. Cardiac apoptosis related LncRNA (CARL) is a newly found lncRNA important for preventing cardiomyocyte apoptosis. Our ongoing study has found that CARL expression is positively related to Notch activation, and knockdown of Notch1 inhibits the expression of CARL. Further analysis of the CARL RNA sequence reveals that there are multiple miRNA binding sites located on CARL for miR212 and miR27b. It has been well established that miR212 and miR27b could inhibits MnSOD and increase NHE1 respectively. Taken together, we propose that Notch activation postburn would increase the expression of CARL, which in turn blocks the function of miR212 and miR27b in a competing endogenous RNA manner. The decreased function of miR212 and miR27b in turn increases MnSOD and decreases NHE1, initiating the endogenous protective strategy to minimize the burn induced cardiac injury. Therefore, our study here intends to investigate the regulatory mechanism of Notch on CARL both in vitro and in vivo models, and clarify the key role of CARL in Notch mediated myocardial protection postburn, finally explore the possible molecular mechanism of CARL-MnSOD/NHE1 regulatory axis. The present study would shed light on developing novel protection target and strategy for burn induced myocardial damage.

心肌细胞凋亡是严重烧伤后心肌损害的主要原因。我们前期研究发现，Notch信号通过增强MnSOD和抑制NHE1，拮抗心肌细胞凋亡，但具体机制不清。CARL是新近发现的与心肌细胞凋亡密切相关的长链非编码RNA，我们预实验发现抑制Notch可下调CARL表达，序列分析发现CARL包含多个可调控MnSOD/NHE1的miRNA（miR212/miR27b）的结合位点。据此我们提出假说：烧伤后Notch上调CARL，后者以竞争性拮抗的方式阻断miRNA的功能，进而调控MnSOD/NHE1表达，发挥内源性心肌保护作用。因此，本项目拟通过体内外实验探讨Notch对CARL的调控机制，并阐明CARL在Notch介导心肌保护中的关键作用，最后分析CARL调控MnSOD/NHE1的分子机制。本课题将进一步丰富烧伤后心肌损害的机制，发现Notch心肌保护的关键下游分子，可能为烧伤后心肌损害提供特异性的干预靶点。

心肌细胞凋亡是严重烧伤后心肌损害的主要原因。我们前期研究发现，Notch信号通过增强MnSOD和抑制NHE1，拮抗心肌细胞凋亡，但具体机制不清。CARL是新近发现的与心肌细胞凋亡密切相关的长链非编码RNA，我们预实验发现抑制Notch可下调CARL表达，序列分析发现CARL包含多个可调控MnSOD/NHE1的miRNA（miR212/miR27b）的结合位点。据此我们提出假说：烧伤后Notch上调CARL，后者以竞争性拮抗的方式阻断miRNA的功能，进而调控MnSOD/NHE1表达，发挥内源性心肌保护作用。因此，本项目拟通过体内外实验探讨Notch对CARL的调控机制，阐明CARL在Notch介导心肌保护中的关键作用，最后分析CARL调控MnSOD/NHE1的分子机制。本课题将进一步丰富烧伤后心肌损害的机制，发现Notch心肌保护的关键下游分子，可能为烧伤后心肌损害提供特异性的干预靶点。.项目先后证实：1. Notch1在烧伤后心肌保护中的核心作用；2.明确烧伤模型中，心肌Notch1可以调控CARL表达；3. 初步发现CARL在烧伤后心肌保护中的重要作用； 4. 通过外泌体靶向心肌策略，证实CARL介导烧伤后心肌保护，并初步发现了CARL-miR212/miR27b- MnSOD/NHE1的可能机制；5. 进一步证实CARL-MnSOD/NHE1介导烧伤后心肌保护的机制；6. 证实Notch1的心肌保护作用是通过CARL介导的MnSOD/NHE1实现。.综上，严重烧伤后，Notch1信号可引起CARL表达增加，后者通过ceRNA的方式，一方面通过miR212提高MnSOD表达水平，另一方面通过miR27b降低NHE1的表达，从而最大程度的降低细胞凋亡，发挥心肌保护作用。.