EXCEEDTHESPACE PROVIDED. Despite recent advances, cytokinesis remains the least understood aspect of the cell cycle. In animal cells, cytokinesis requires the coordination of multiple cellular components including the microtubule cytoskeleton, the actin cytoskeleton and membrane traffic. Today, it is not clear how these components are regulated and how they interact with each other. The long-term goal of this project is to define the elements involved in cytokinesis and to understand how these elements integrate to accomplish cytokinesis. Toward that goal, two proteins required for cytokinesis in Dictyostelium have been identified. These proteins provide a handle on two different pathways that come together during cytokinesis. The objective of this grant is to dissect the contribution of these pathways during cytokinesis: 1) The role of LvsA in osmorequlation and cytokinesis will be defined. LvsA is a member of the novel beach family of membrane trafficking proteins and is required for cytokinesis and for the function of the contractile vacuole. This provides the opportunity to dissect the contribution of membrane traffic to cytokinesis in a simple model system. The functional contribution of each of the LvsA domains to its localization and function in vivo will be ascertained. Binding- partners for LvsA will be identified and their requirement for cytokinesis will be tested. Genetic suppressors of LvsA will be isolated and the mechanism of suppression will be determined. These studies will illuminate our understanding of membrane processes in cytokinesis and also how mutations in a human homologue of LvsA (LYST) cause a human disorder, the Chediak-Higashi Syndrome. 2) The signaling pathway that requires RacE durinq cytokinesis will be defined. The small GTPase RacE is essential for the development of cortical tension and for the ingression of the cleavage furrow during cytokinesis. A combination of approaches will be used to dissect the mechanisms by which racE controls cytokinesis. A model that explains the role of RacE during cytokinesis is proposed based on recent data from several laboratories on proteins required in cytokinesis. Several predictions made by this model will be tested, among them: a) that RacE controls the organization of Cortexillins at the cleavage furrow though the activation of specific IQGAPs; b) that the GAP domain of DdRacGAP1 modulates the activity of RacE in vivo. In addition, a method to purify RacE has been developed and will be used to identify novel binding partners for racE. The role of these proteins in cytokinesis will be determined by biochemical and genetic approaches. PERFORMANCESITE( ========================================Section End===========================================
| Falkenstein, Kristin; De Lozanne, Arturo (2014) Dictyostelium LvsB has a regulatory role in endosomal vesicle fusion. J Cell Sci 127:4356-67 |
| Kypri, Elena; Falkenstein, Kristin; De Lozanne, Arturo (2013) Antagonistic control of lysosomal fusion by Rab14 and the Lyst-related protein LvsB. Traffic 14:599-609 |
| Wen, Yujia; Stavrou, Irene; Bersuker, Kirill et al. (2009) AP180-mediated trafficking of Vamp7B limits homotypic fusion of Dictyostelium contractile vacuoles. Mol Biol Cell 20:4278-88 |
