SH2-Containing Inositol 5′-Phosphatase SHIP2 Associates with the p130^Cas Adapter Protein and Regulates Cellular Adhesion and Spreading

Abstract

In a previous study, we found that the SHIP2 protein became tyrosine phosphorylated and associated with the Shc adapter protein in response to the treatment 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 describe here a novel interaction between SHIP2 and the p130^Cas adapter protein, a mediator of actin cytoskeleton organization. SHIP2 and p130^Cas association was detected in anti-SHIP2 immunoprecipitates from several cell types. Reattachment of trypsinized cells stimulated tyrosine phosphorylation of SHIP2 and increased the formation of a complex containing SHIP2 and a faster-migrating tyrosine-phosphorylated form of p130^Cas. The faster-migrating form of p130^Cas was no longer recognized by antibodies to the amino terminus of p130^Cas and appeared to be generated through proteolysis. Interaction of the SHIP2 protein with the various forms of p130^Cas was mediated primarily through the SH2 domain of SHIP2. Immunofluorescence studies indicated that SHIP2 localized to focal contacts and to lamellipodia. Increased adhesion was observed in HeLa cells transiently expressing exogenous WT-SHIP2. These effects were not seen with SHIP2 possessing a mutation in the SH2 domain (R47G). Transfection of a catalytic domain deletion mutant of SHIP2 (ΔRV) inhibited cell spreading. Taken together, our studies suggest an important role for SHIP2 in adhesion and spreading.

ACKNOWLEDGMENTS

We thank Bruce Mayer for GST-Cas expression construct and Alan Saltiel and Roman Herrera for helpful discussions.