Phosphorylated Tyr142 ß-catenin localizes to centrosomes and is regulated by Syk.

ß-catenin is a central component of adherent junctions and a key effector of canonical Wnt signaling, in which dephosphorylated Ser/Thr ß-catenin regulates gene transcription. ß-catenin phosphorylation at Tyr142 (PTyr142 ß-catenin), which is induced by receptor and Src family Tyr kinases, represents a previously described ß-catenin switch from adhesive to migratory roles. In addition to classical ß-catenin roles, phosphorylated Ser/Thr ß-catenin and total ß-catenin were involved in centrosomal functions, including mitotic spindle formation and centrosome separation. Here we find that PTyr142 ß-catenin is present in centrosomes in non-transformed and glioblastoma cells and that, in contrast to the Ser/Thr phosphorylated ß-catenin, PTyr142 ß-catenin centrosomal levels drop in mitosis. Furthermore, we show that the inhibitor of Spleen Tyrosine Kinase (Syk) piceatannol decreases centrosomal PTyr142 ß-catenin levels, indicating that Syk regulates centrosome PTyr142 ß-catenin. Our findings suggest that PTyr142 ß-catenin and Syk may regulate centrosomal cohesion. This study highlights the contribution of different phosphorylated ß-catenin forms to the cell and centrosome cycles.