SH2-containing inositol 5 '-phosphatase SHIP2 associates with the p130(Cas) adapter protein and regulates cellular adhesion and spreading

In a previous study, we found that the SHIP2 protein became tyrosine phosph orylated and associated with the Shc adapter protein in response to the tre atment of cells with growth factors and insulin (T. Habib, J. A. Hejna, R. E. Moses, and S. J. Decker, J. Biol. Chem. 273:18605-18609, 1998). We descr ibe here a novel interaction between SHIP2 and the p130(Cas) adapter protei n, a mediator of actin cytoskeleton organization. SHIP2 and p130(Cas) assoc iation was detected in anti-SHIP2, immunoprecipitates from several cell typ es. Reattachment of trypsinized cells stimulated tyrosine phosphorylation o f SHIP2 and increased the formation of a complex containing SHIP2 and a fas ter-migrating tyrosine-phosphorylated form of p130(Cas). The faster-migrati ng form of p130(Cas) was no longer recognized by antibodies to the amino te rminus of p130(Cas) and appeared to be generated through proteolysis. Inter action of the SHIP2 protein with the various forms of p130(Cas) was mediate d primarily through the SH2 domain of SHIP2. Immunofluorescence studies ind icated that SHIP2 localized to focal contacts and to lamellipodia. Increase d adhesion was observed in HeLa cells transiently expressing exogenous WT-S HIP2. These effects were not seen with SHIP2 possessing a mutation in the S H2 domain (R47G). Transfection of a catalytic domain deletion mutant of SHI P2 (Delta RV) inhibited cell spreading. Taken together, our studies suggest an important role for SHIP2 in adhesion and spreading.