Focal adhesion kinase-dependent focal adhesion recruitment of SH2 domains directs SRC into focal adhesions to regulate cell adhesion and migration

Directed cell migration requires dynamical control of the protein complex within focal adhesions (FAs) and this control is regulated by signaling events involving tyrosine phosphorylation. We screened the SH2 domains present in tyrosine-specific kinases and phosphatases found within FAs, including SRC, SHP1 and SHP2, and examined whether these enzymes transiently target FAs via their SH2 domains. We found that the SRC-SH2 domain and the SHP2-N-SH2 domain are associated with FAs, but only the SRC-SH2 domain is able to be regulated by focal adhesion kinase (FAK). The FAK-dependent association of the SRC-SH2 domain is necessary and sufficient for SRC FA targeting. When the targeting of SRC into FAs is inhibited, there is significant suppression of SRC-mediated phosphorylation of paxillin and FAK; this results in an inhibition of FA formation and maturation and a reduction in cell migration. This study reveals an association between FAs and the SRC-SH2 domain as well as between FAs and the SHP2-N-SH2 domains. This supports the hypothesis that the FAK-regulated SRC-SH2 domain plays an important role in directing SRC into FAs and that this SRC-mediated FA signaling drives cell migration.