WDR1 is a novel EYA3 substrate and its dephosphorylation induces modifications of the cellular actin cytoskeleton

Eyes absent (EYA) proteins are unusual proteins combining in a single polypeptide chain transactivation, threonine phosphatase, and tyrosine phosphatase activities. They play pivotal roles in organogenesis and are involved in a variety of physiological and pathological processes including innate immunity, DNA damage repair or cancer metastasis. The molecular targets of EYA tyrosine phosphatase activity are still elusive. Therefore, we sought to identify novel EYA substrates and also to obtain further insight into the tyrosine-dephosphorylating role of EYA proteins in various cellular processes. We show here that Src kinase phosphorylates tyrosine residues in two human EYA family members, EYA1 and EYA3. Both can autodephosphorylate these residues and their nuclear and cytoskeletal localization seems to be controlled by Src phosphorylation. Next, using a microarray of phosphotyrosine-containing peptides, we identified a phosphopeptide derived from WD-repeat-containing protein 1 (WDR1) that is dephosphorylated by EYA3. We further demonstrated that several tyrosine residues on WDR1 are phosphorylated by Src kinase, and are efficiently dephosphorylated by EYA3, but not by EYA1. The lack of phosphorylation generates major changes to the cellular actin cytoskeleton. We, therefore, conclude that WDR1 is an EYA3-specific substrate, which implies that EYA3 is a key modulator of the cytoskeletal reorganization.