| Description |
The actin cytoskeleton of eukaryotic cells plays an essential role in the biological functions necessary for survival. In addition to facilitating organelle arrangement and transport, the actin cytoskeleton is a major component of the machinery which brings about cell movement and division. Thus, a major aim of current biological research is to understand how the cytoskeleton is controlled. A number of proteins are thought to play a role in the regulation of cytoskeletal dynamics, including proteins such as the oncoprotein, VAV, that function to activate members of the Rho family of monomeric GTPases. VAV is a multifunctional protein with homologs identified in humans, mice, and recently in the nematode, Caenorhabditis elegans. It is a Guanine Nucleotide Exchange Factor (GEF), which activates Rho family GTPase proteins by promoting the release of molecular GDP from the GTPase, so that GTP can bind to the GTPase, and activate it. Deletion of the amino terminus of VAV results in constitutive activation. Relatively little is known about the function of VAV, yet it is notable to mention that there is a high degree of conservation among the mammalian VAV and the C. elegans homolog, VAV-1. This presents a unique opportunity to study the function of VAV in a simple system, allowing for easy genetic analysis using the powerful genetic engineering capabilities available in C. elegans. In this project, I constructed five different plasmid DNA constructs of VAV-1, each containing different combinations of important functional domains, for transfection into mammalian fibroblasts. Upon transfection, I hope to see the presence of enlarged foci, due to the oncogenic activity of truncated versions of VAV-1; I also hope to see the polymerization of various cytoskeletal structures, due to the ability of the constitutively active forms of VAV-1 to promote GEF activity on Rho family GTPases, thus affecting cytoskeletal signaling pathways. These results will be important for solidifying a role for VAV in the signaling pathways in a simple system, providing a correlation with cytoskeletal dynamics and regulation pathways in the more complicated systems of higher organisms. |
