Focal adhesion kinase activates Stat1 in integrin-mediated cell migration and adhesion.

Recent studies suggest that focal adhesion kinase (FAK) is important for cell migration. We now suggest a mechanism by which FAK activates the signal transducer and activator of transcription (STAT) pathway, regulating cell adhesion and migration. In particular, we observe that FAK is capable of activating Stat1, but not Stat3. Co-immunoprecipitation and in vitro binding assays demonstrate that Stat1 is transiently and directly associated with FAK during cell adhesion, and Stat1 is activated in this process. FAK with a C-terminal deletion (FAKDeltaC14) completely abolishes this interaction, indicating this association is dependent on the C-terminal domain of FAK, which is required for FAK localization at focal contacts. Moreover, Stat1 activation during cell adhesion is diminished in FAK-deficient cells, correlating with decreased migration in these cells. Finally, we show that depletion of Stat1 results in an enhancement of cell adhesion and a decrease in cell migration. Thus, our results have demonstrated, for the first time, a critical signaling pathway from integrin/FAK to Stat1 that reduces cell adhesion and promotes cell migration.