β-Arrestin1 and Signal-transducing Adaptor Molecule 1 (STAM1) Cooperate to Promote Focal Adhesion Kinase Autophosphorylation and Chemotaxis via the Chemokine Receptor CXCR4

The chemokine receptor CXCR4 and its chemokine ligand CXCL12 mediate directed cell migration during organogenesis, immune responses, and metastatic disease. However, the mechanisms governing CXCL12/CXCR4-dependent chemotaxis remain poorly understood. Here, we show that the beta-arrestin1.signal-transducing adaptor molecule 1 (STAM1) complex, initially identified to govern lysosomal trafficking of CXCR4, also mediates CXCR4-dependent chemotaxis. Expression of mini-gene fragments from beta-arrestin1 or STAM1, known to disrupt the beta-arrestin1.STAM1 complex, and RNAi against beta-arrestin1 or STAM1, attenuates CXCL12-induced chemotaxis. The beta-arrestin1.STAM1 complex is necessary for promoting autophosphorylation of focal adhesion kinase (FAK). FAK is necessary for CXCL12-induced chemotaxis and associates with and localizes with beta-arrestin1 and STAM1 in a CXCL12-dependent manner. Our data reveal previously unknown roles in CXCR4-dependent chemotaxis for beta-arrestin1 and STAM1, which we propose act in concert to regulate FAK signaling. The beta-arrestin1.STAM1 complex is a promising target for blocking CXCR4-promoted FAK autophosphorylation and chemotaxis.