肿瘤低氧微环境下AMPK/NIX通路调控线粒体自噬而重塑细胞能量代谢的机制研究

Under certain physiological or pathological conditions, cells start the mitophagy program to eliminate the unnecessary or impaired mitochondria, which is important for the mitochondrial quality control and the maintenance of homeostasis. The hypoxic tumor microenvironment is closely related to the reprogramming energy metabolism of tumor cells. The hypoxia-induced mitophagy inhibits the mitochondrial oxidative phosphorylation in tumor cells to fit for the hypoxia feature of tumor microenvironment, and the recycling of degradation products generated by mitophagy provides material and energy resources for the growth of tumor cells. To date, the mitochondrial outer-membrane protein NIX has been proved to be a selective receptor for mitophagy, but the mechanism of its regulation of mitophagy is not yet known. This project will simulate the hypoxic tumor microenvironment and focus on the hypoxia-induced mitophagy in tumor cells. First, we will explored whether the key protein of mitophagy NIX is phosphorylated and activated by AMPK, which is activated in response to hypoxia. Second, we will screen the proteins that interact with NIX and study the effect of the dynamic phosphorylation of NIX on the protein-protein interaction. Then, we will explore the regulatory mechanism of mitophagy and the reprogramming energy metabolism through the AMPK/NIX pathway. Furthermore, we will study the digestion of the specific cargos for autophagy by chymotrypsin B. The results will state a novel regulation pathway of mitophagy in tumor cells through the phosphorylation of NIX by AMPK, explorer the significance of mitophagy in reprogramming energy metabolism of tumor cells, and provide some clues for the prevention and treatment of related major diseases.

在某些生理或病理条件下细胞启动线粒体自噬程序以清除多余或受损线粒体，这对线粒体质量控制和维持细胞内稳态具有重要意义。肿瘤低氧微环境与其能量代谢重塑关系密切，低氧诱导的线粒体自噬下调氧化磷酸化作用，以适应肿瘤微环境的低氧特性；而降解产物回收利用为肿瘤细胞生长提供了物质和能量来源。目前已证实线粒体外膜蛋白NIX是线粒体自噬的选择性受体之一，但其分子机制尚不明确。本项目将模拟肿瘤低氧微环境，以低氧诱导线粒体自噬为切入点，明确AMPK感应低氧后是否磷酸化并激活NIX；筛选与NIX相互作用的蛋白，研究NIX的动态磷酸化对蛋白质相互作用的影响；探索AMPK/NIX调控线粒体自噬及重塑能量代谢的分子机制；并研究溶酶体胰凝乳蛋白酶在自噬过程中的作用。研究结果将探索AMPK通过磷酸化NIX而促进肿瘤细胞线粒体自噬的新调控途径，阐明线粒体自噬对肿瘤细胞能量代谢重塑的重要性，为预防、治疗相关重大疾病提供线索。

在某些生理或病理条件下细胞启动线粒体自噬程序以清除多余或受损线粒体，这对线粒体质量控制和维持细胞内稳态具有重要意义。肿瘤低氧微环境与其能量代谢重塑关系密切，低氧诱导线粒体发生能量代谢重塑，下调氧化磷酸化作用、代偿性上调糖酵解作用，从而使得肿瘤细胞适应肿瘤微环境的低氧特性。目前已证实线粒体外膜蛋白NIX是线粒体自噬的选择性受体之一，但其分子机制尚不明确。本项目模拟肿瘤低氧微环境，以低氧、药物诱导肿瘤细胞能量代谢重塑为切入点，通过精确解析肿瘤细胞的能量代谢模式，探索线粒体重要功能蛋白（包括自噬相关蛋白NIX、线粒体分子伴侣TRAP1等）调控线粒体自噬及重塑能量代谢的分子机制。研究结果有助于阐明线粒体自噬对肿瘤细胞能量代谢重塑的重要性，为预防、治疗相关重大疾病提供线索。