心肌缺血/再灌注损伤新机制：USP7介导的心肌细胞凋亡和铁坏死

凋亡和铁坏死是缺血/再灌注（I/R）心肌细胞死亡的两种重要方式。本项目预实验首次发现：I/R大鼠心肌组织泛素特异性蛋白酶7（USP7）表达上调，USP7抑制剂能减轻I/R损伤；沉默USP7可减少低氧/复氧（H/R）诱导的心肌细胞凋亡和铁坏死，伴随p53和转铁蛋白受体1(TfR1)蛋白水平下降；而降低MLC20磷酸化水平则可阻止I/R诱导的USP7表达。我们因而率先提出：心肌I/R时，USP7表达上调促进了心肌细胞凋亡和铁坏死，其机制可能与升高p53和TfR1蛋白水平有关，USP7表达受MLC20调节。利用I/R（或H/R）大鼠（或心肌细胞）模型，结合药物干预、基因沉默等，本项目拟明确USP7促心肌细胞凋亡和铁坏死作用；确定USP7通过p53和TfR1促凋亡和铁坏死机制；阐明MLC20对USP7的表达调节机制。本项目将有助于阐明心肌I/R损伤新机制，为寻找防治心肌I/R损伤新药提供理论依据。

Apoptosis and ferroptosis are two important types of cell death following myocardial ischemia/reperfusion (I/R). The preliminary data of this project showed that in rat model of myocardial I/R, the expression of ubiquitin specific protease 7(USP7) was up-regulated in myocardial tissue and the USP7 inhibitor could attenuate the I/R injury; silence of USP7 was able to block hypoxia/reoxygenation (H/R) -induced myocardial apoptosis and ferroptosis concomitant with a decrease in p53 and transferrin receptor 1 (TfR1) levels; the decrease in phosphorylation level of myosin regulatory light chain(MLC20) attenuated the expression of USP7. Based on these observations, we hypothesize for the first time that the up-regulation of USP7 promoted myocardial apoptosis and ferroptosis following I/R, which might be related to increase of p53 and TfR1 protein levels; while the expression of USP7might be modulated by MLC20. In the I/R or H/R injury model, combining the methods of drug interference and gene silence, etc., we will mainly focus on the research as follows: confirming the role of USP7 in promotion of myocardial apoptosis and ferroptosis; verifying the mechanisms for USP7-mediated apoptosis and ferroptosis; and elucidating the regulatory mechanisms for USP7 expression. This project will lay a theoretic foundation and provide the new idea for seeking novel drug targets against myocardial ischemia.