胞质分裂期RhoA的时空调控分子机制研究

Cytokinesis is a fundamental biological process in which the parent cell physically separates and sequesters the duplicated genetic materials into two daughter cells. Cytokinesis starts just after anaphase onset with cleavage furrow formation. Proper completion of cytokinesis involves exquisite temporal and spatial coordination between the actin and microtubule cytoskeletal systems. Failure of cytokinesis causes polyploidy which has been associated with cancer. The small GTPase RhoA is the master regulator of cytokinesis, which is activated by centralspindlin and its GEF (guanine nucleotide exchange factor) ECT-2..This study will use an optogenetic-based technology called TULIPs (tunable, light-controlled interacting protein tags), allowing light-directed control of protein localization and protein-protein interactions, combining with live-cell imaging microscopy, to dissect spatial-temporal regulation of RhoA during cytokinesis in C. elegance early embryonic cells. In addition, this study will investigate roles of centralspindlin subunit CYK-4 on positive feedback regulation pathways of RhoA during cytokinesis.

细胞分裂是生物体生长和繁殖的基础，细胞分裂失控常常导致特定细胞的异生、增生甚至肿瘤的出现。在细胞分裂过程中，胞质分裂发生在特定的位置和时间，使母代细胞物理上分为两个子代细胞，并决定了子代细胞内遗传物质、细胞内容物的正确含量，是维持细胞稳态的关键。胞质分裂的核心驱动因子是小G蛋白Rho家族成员RhoA。本课题将结合现代光遗传学技术TULIP系统和定量荧光活体细胞成像技术，通过在线虫早期胚胎细胞中的细胞膜不同区域或细胞周期不同阶段光招募RhoA激活因子ECT-2 GEF活性，研究在胞质分裂期间RhoA被激活的时空调控分子机制，以及RhoA下游与收缩环组装相关各效应因子的活性与细胞周期的相关性。本课题还将通过光遗传学技术和体外重建实验，研究centralspindlin复合体CYK-4亚基对RhoA活性的正反馈调节机制。

本项目结合了遗传学、细胞生物学、RNA组学、生物化学等多种研究手段，以秀丽隐杆线虫早期胚胎细胞为研究系统，对线虫早期胚胎细胞的不对称分裂和生殖细胞命运决定因子在胚胎中的极性分布进行了研究。本项目发现APC/C复合体调控RNA结合蛋白OMA-1在胚胎极性形成过程中的不对称分布，进而影响了下游细胞命运决定因子的极性分布。本项目还发现RNA结合蛋白DEAD box RNA解旋酶GLH-1/VASA调控P颗粒在早期胚胎细胞中的时空动态分布的机制。本项目所获得的数据和结论使我们对早期胚胎中细胞的极性形成、细胞命运决定因子的不对称分布的机制有了更进一步的认识，并对RNA结合蛋白在配子-合子转化过程以及之后的胚胎早期发育过程的作用有了进一步了解。