Transformation and pp60^v-src autophosphorylation correlate with SHC-GRB2 complex formation in rat and chicken cells expressing host-range and kinase-active, transformation-defective alleles of v-src

The biochemical properties of several pp60^v-src substrates believed to participate in src-mediated transformation were examined in cells expressing a kinase-active, transformation-defective v-src allele (v-src-F172Δ/Y416F) and its parental allele, v-src-F172Δ, a host-range-dependent allele that transforms chicken cells to a fusiform morphology, but does not transform rat cells. Because pp60^v-src-F172Δ is dependent on autophosphorylation for transforming ability, these alleles provide a unique opportunity to examine the role of pp60^v-src autophosphorylation in regulating substrate interactions. Increased pp125^FAK tyrosine phosphorylation and high levels of pp60^v-src-associated phosphotidylinositol-3' kinase activity were detected specifically in chicken cells exhibiting round, refractile transformation but not in cells transformed to a fusiform morphology. Increased pp125^FAK kinase activity, but not increased pp125^FAK tyrosine-phosphorylation correlated with pp60^v-src autophosphorylation and increased anchorage-independent growth. Thus, pp125^FAK and PI3'K may participate in morphological transformation by v-src. Furthermore, association of phosphorylated SHC with the adapter GRB2 correlated with increased anchorage-independent growth (and autophosphorylation) in both rat and chicken cells independent of the morphological phenotype induced. Therefore, host-range dependence for transformation may be regulated through association of SHC with GRB2, thus implicating SHC as a crucial substrate for src-dependent transformation.