DIP/WISH-deficient mice reveal Dia- and N-WASP-interacting protein as a regulator of cytoskeletal dynamics in embryonic fibroblasts.

DIP/WISH binds to mammalian diaphanous and N-WASP, and functions as a scaffold protein by binding to Nck protein (called SPIN90). In addition, DIP/WISH accelerates actin polymerization through integration with N-WASP and is involved in cytoskeletal dynamics. We previously reported that DIP controls the activities of Rho GTPases in a Src-dependent manner, and accordingly contributes to cell motility (Meng et al. 2004). Here, we made the mice lacking DIP/WISH and demonstrated that DIP/WISH is critical for cell motility and adhesion by using murine embryonic fibroblasts (MEF). Rho activity was higher in DIP/WISH-deficient MEF cells even before platelet-derived growth factor (PDGF) or adhesion stimulation. Cell motility and adhesion were impaired in DIP/WISH-deficient MEF cells, and the MEF cells moved little probably due to the deficiency of tail retractions although they had many small membrane ruffles. Consistent with high Rho activity, DIP/WISH-deficient MEF cells exhibited many stress fibers due to clustering pre-existing actin filament. Thus, DIP/WISH is a negative regulator of Rho and modulates cell adhesion by controlling the integration of adhesion molecules.