Amy L. Wilson-Delfosse, Ph.D.
Ph.D. (pharmacology), Vanderbilt
Associate Professor of Pharmacology
Phone: (216) 368-3494
Fax: (216) 368-3395
E-mail: amy.wilson-delfosse@case.edu
Wood RT-301
Research
Ras-related small GTP-binding proteins function as molecular switches that regulate diverse physiological processes within mammalian cells. Our laboratory focuses on the study of the Rho subfamily of GTPases (Rho, Rac and Cdc42). These proteins are involved in the regulation of cell polarity, motility, cell cycle progression and cellular transformation. Since activation of Ras superfamily GTPases and their associated signal transduction cascades are dependent upon proper positioning of the GTPase in the cell, we are particularly interested in the mechanisms by which this family of GTPases is targeted to the various compartments of the cell. For example, Cdc42 is found in the Golgi, the plasma membrane and the cytosol, while Rac1 is primarily localized to the plasma membrane and the cytosol. Typically, the membrane associated GTPases are activated and competent to signal, while the cytosolic forms of the GTPases are held in an inactive state via their interaction with the negative regulatory protein, Rho GDP-dissociation inhibitor. It is a primary goal of this laboratory to define and characterize the protein-protein interactions that regulate the targeting of this family of GTPases in mammalian cells. We believe that the determination of the cellular processes that regulate membrane targeting and retention of inactive Rho GTPases in the cytosol is a critical component in the overall understanding of Rho GTPase biology. These studies are likely to be relevant to the study of cancer cell growth as well as a variety of other physiological processes that are dependent on cell shape and motility.
A wide variety of techniques are used in the laboratory including PCR-based mutagenesis, transient transfection of mammalian cells, standard and two-dimensional SDS-polyacrylamide gel electrophoresis, Western blotting, yeast two-hybrid screens, GST pull down assays, biochemical purifications and indirect immunofluorescence.
Selected References
Gibson, R.M. and Wilson-Delfosse, A.L. (2001) A RhoGDI-binding defective mutant of Cdc42Hs targets to membranes and activates filopodia formation but does not cycle with the cytosol of mammalian cells. Biochem J. 359, 285-294.
Gandhi, P.N., Gibson, R.M., Tong, X., Miyoshi, J., Takai, Y., Konieczkowski, M., Sedor, J.R. and Wilson-Delfosse, A.L. (2004) An activation mutant of Rac1 that fails to interact with Rho GDP-dissociation Inhibitor stimulates membrane ruffling in mammalian cells Biochem. J. 378, 409-419.
Gibson, R.M., Gandhi, P.N., Tong, X., Miyoshi, J., Takai, Y., Konieczkowski, M., Sedor, J.R. and Wilson-Delfosse, A.L. (2004) An activating mutant of Cdc42Hs that fails to interact with RhoGDI localizes to the plasma membrane and mediates actin reorganization. Exp. Cell Res. 301, 211-222.