RhoA是细胞分裂及细胞迁移中最重要的调控因子。它的异常会破坏胚胎正常发育，甚至引发癌细胞发生及其侵袭转移。目前已知在细胞分裂中，中央纺锤体复合体(简称:复合体) 及NOP-1同时调节RhoGEF ECT-2的活性，进而激活RhoA并介导收缩环形成。但RhoA激活通路的机理还未被完全了解，而且很可能还存在未知的调节蛋白。因此，近期我们进行了线虫全基因组的RNAi筛选，发现SAO-1可能调节RhoA的激活。在敲低SAO-1表达后，中央纺锤体结构变得不稳定, 表明了复合体蛋白不能正常定位于中央纺锤体; 且细胞膜的收缩能力减弱，这也表明了RhoA的活性受到影响。因此，我们推测SAO-1可能通过调节复合体的活性及分布以介导RhoA的激活。本项目拟通过研究SAO-1在细胞分裂中的功能，了解它如何调控复合体蛋白的定位和转运，以明确RhoA激活通路的机理，让我们对癌症等相关疾病的分子机制有进一步的认识。

RhoA, a small GTPase, is the key regulator of cytoskeleton. During cell division, ECT-2 mediates RhoA activation by catalyzing guanine nucleotide exchange on RhoA, consequently mediates the formation of contractile ring. The activation and localization of ECT-2 is regulated by centralspindlin (CYK-4 and ZEN-4). In addition, our recent data also demonstrate that ECT-2 activation and cell membrane recruitment is regulated by NOP-1 and PAR-5, respectively. This indicates unknown proteins may present in the RhoA activation pathway. Recently, we have performed a genome-wide high-throughput RNAi screening, and our results showed that SAO-1 may involve in RhoA activation pathway. Cell membrane contractility and central spindle integrity are affected in sao-1 depleted C. elegans zygote. These indicate SAO-1 may regulate RhoA activation through ZEN-4/CYK-1. In this proposal, we are going to elucidate the molecular mechanism of SAO-1-mediated RhoA activation pathway. We will investigate the molecular function of SAO-1 during cytokinesis, how SAO-1 regulates centralspindlin and what is the protein domain involved in this pathway.