缺氧细胞中mTORC1通过下调EF-Tumt表达引起线粒体损害的分子机制研究

项目名称： 缺氧细胞中mTORC1通过下调EF-Tumt表达引起线粒体损害的分子机制研究

项目编号： No.81201465

项目类型： 青年科学基金项目

立项/批准年度： 2013

项目学科： 医学四处

项目作者： 张东霞

作者单位： 中国人民解放军第三军医大学

项目金额： 23万元

中文摘要： 烧伤早期损害的实质是缺血缺氧损害，线粒体受损是核心步骤，其机制与调控环节尚不明确。本课题组前期发现，缺氧使线粒体翻译延伸因子Tu（EF-Tumt）表达降低；常氧时，低表达EF-Tumt即引起线粒体损害，提示EF-Tumt低表达介导缺氧后线粒体损害。文献报告，缺氧使雷帕霉素靶蛋白（mTOR）活性降低，本组进一步发现单用mTOR复合体1（mTORC1）抑制剂雷帕霉素即可引起EF-Tumt表达下降。基于上述事实本课题提出"缺氧通过mTORC1调控EF-Tumt表达引起线粒体损害"的假设。拟明确mTORC1对EF-Tumt表达与线粒体功能的调控，构建mTORC1稳定活化/失活细胞系，探讨缺氧时mTORC1活性对EF-Tumt表达与线粒体功能的影响；在此基础上，进一步干预EF-Tumt表达，阐明mTORC1调控线粒体功能的分子机制。通过本研究，有望从新的角度揭示缺氧后线粒体损伤发生机制与调控环节。

中文关键词： 缺氧；心肌细胞；线粒体翻译延伸因子Tu；mTORC1；自噬

英文摘要： Ischemia/hypoxia injury is common in severe burn, and mitochondrial damage plays an important role in mediating ischemic/hypoxic myocardial injury. However, the underlying mechanisms remain to be illustrated. Our previous studies have found that hypoxia causes decreased expression of EF-Tumt in cardiomyocytes, and down-regulation of EF-Tumt level by siRNA leads to mitochondrial damage under normoxia condition, suggesting that decreased expression of EF-Tumt leads to mitochondrial damage in hypoxic cardiomyocytes. It has been reported that hypoxia decreased mTOR activities in multiple cells, to explore the key molecules at the up-stream of EF-Tumt, we treated cardiomyocytes with a mTOR complex 1 (mTORC1) inhibitor-rapamycin, and found that rapamycin decreased EF-Tumt expression in cardiomyocytes. Thus, we hypothesize that mTORC1 plays an important role in mediating mitochondrial damage via down-regulation of EF-Tumt level in hypoxic cardiomyocytes. To confirm this hypothesis, firstly, we investigated the changes of EF-Tumt level and mitochondrial functions regulated by mTORC1; Secondly, we down or up-regulate the mTORC1 activity through constructing Raptor or TSC2 RNAi vector in H9C2 cell, and investigate its role in regulating EF-Tumt expression and mitochondrial functions under hypoxia; Further, we investigate

英文关键词： hypoxia；cardiomyocyte；mitochondria translation elongation factor Tu；mTORC1；autophagy