蛋白质异戊二烯化调控初级卵泡/次级卵泡转换的作用与机制研究

卵泡发育过程中，卵母细胞/颗粒细胞相互作用共同生长。在卵母细胞特异敲除蛋白质异戊二烯化修饰的关键基因香叶基香叶基焦磷酸合成酶(GGPPS)后，小鼠出现初级卵泡/次级卵泡发育阻滞的现象，其原因可能是颗粒细胞增殖受到抑制，卵母细胞线粒体自噬增加导致的能量代谢低下。本课题进一步构建GGPPS卵母细胞和颗粒细胞的时空特异敲除小鼠，以初级卵泡/次级卵泡发育转换为研究对象，从卵母细胞/颗粒细胞物质和信号交流以及线粒体功能的全新角度阐明卵泡发育的新机制。研究GGPPS控制的蛋白质异戊二烯化修饰如何影响Stat3的磷酸化，调控其进入细胞核和线粒体行使功能；鉴定线粒体的异戊二烯化修饰蛋白质，研究其在氧化磷酸化、线粒体自噬和初级卵泡/次级卵泡转换过程中的作用。我们提出卵泡发育存在“线粒体检验点”的概念：即线粒体的质量和数量对卵泡进入下一个发育阶段至关重要，这一概念对细胞的其他生理和病理过程具有广泛的指导意义。

During the follicle growth, oocyte and surrounding granulosa cells develop together as a unit through information communication and material exchange. We found that when we deleted the gene of geranylgeranyl diphosphate synthase (GGPPS) in mouse oocyte, a key enzyme controlling the balance of protein geranylgeranylation and farnesylation, the developmental transition of primary follicle to secondary follicle was prohibited because of the defect of granulosa proliferation and mitophage of oocyte mitochondria. In this project, we will spatiotemporally delete GGPPS in oocyte and granulosa cell through crossing GGPPS-LoxP and different Cre mice to study how the balance of geranylgeranylation and farnesylation regulates the communication between oocyte and granulosa, and the function of mitochondria in oocyte during the follicle development. We will focus the mediation of Stat3 phosphorylation, which has been proved to regulated by geranylgeranylated Rac1, that controls the nucleus localization that activate gene transcription like GDF9, and mitochondrion localization that regulate oxidative phosphorylation. We will also identify the mitochondria proteins that might be geranylgeranylated and farnesylated and study their function on oxidative phosphorylation, mitophage and primary to secondary follicle transition. We further propose the concept of "mitochondria checkpoint" during follicle development that would examine the quality and quantity of mitochondria. To fulfill the condition of mitochondria checkpoint is critical for the transition of follicle to next stage. This concept would be able to apply to other physiological and pathological processes.