Abstract
Dorsal closure is the last major process in Drosophila embryogenesis that mediated by two main forces, which provided by actomyosin in different cells. Actomyosin forms purse-string at leading edge of dorsal-most epidermal (DME) cells, which provide force for zippering, and the circumferential and cortical actomyosin coordinately reduce apical area by amnioserosa (AS) constriction. The cytoskeleton also participates in the cell remodeling process. Echinoid (Ed) is an adhesion molecule, which normally is completely removed at stage 13 in amnioserosa and causes premature AS constriction when ectopically expressed at same stage. However, how actomyosin regulates AS constriction remains unknown. In this study, we found that ectopically express non-degrable Ed cause premature AS constriction and extensively accumulation of actin. Therefore, we used genetic screen to investigate which actin regulator participates in AS constriction process. The results demonstrated that most of actin regulators, which we used in this study, participated in the Ed-mediated AS constriction but fewer involved in the normal AS constriction. We also found that actin and microtubule might participate in Ed-mediated or normal AS constriction event. Together, my thesis identified the specific actin regulators mediating AS constriction by affecting cytoskeleton in Ed-mediated or normal status.