Abl kinase interacts with and phosphorylates vinexin

Non-receptor tyrosine kinase Abl is a well known regulator of the actin-cytoskeleton, including the formation of stress fibers and membrane ruffles. Vinexin is an adapter protein consisting of three SH3 domains, and involved in signal transduction and the reorganization of actin cytoskeleton. In this study, we found that vinexin alpha as well as beta interacts with c-Abl mainly through the third SH3 domain, and that vinexin and c-Abl were colocalized at membrane ruffles in rat astrocytes. This interaction was reduced by latrunculin B, suggesting an F-actin-mediated regulatory mechanism. We also found that vinexin alpha but not beta was phosphorylated at tyrosine residue when c-Abl or v-Abl was co-expressed. A mutational analysis identified tyrosine 127 on vinexin alpha as a major site of phosphorylation by c- or v-Abl. These results suggest that vinexin alpha is a novel substrate for Abl.