BP75, Bromodomain-containing Mr 75,000 Protein, Binds Dishevelled-1 and Enhances Wnt Signaling by Inactivating Glycogen Synthase Kinase-3ß

Abstract

To identify novel regulators of Wnt signaling, we performed yeast two-hybrid analyses with Dvl-1 and identified BP75 as a candidate. Here, we demonstrated that BP75 directly interacts with Dvl-1 in mammalian cells and enhances TCF-dependent gene expression induced by Dvl-1. In support of these results, BP75 in cooperation with Dvl-1 was found to facilitate dephosphorylation at Tyr216 of glycogen synthase kinase-3beta and consequently inhibit its kinase activity. Furthermore, the nuclear translocation and formation of vesicular structures of beta-catenin were induced by BP75 and Dvl-1 in a synergistic manner. Collectively, these results provided us a novel mechanism in Wnt signaling where BP75 plays important regulatory roles between glycogen synthase kinase-3beta and Dvl.