p120-catenin in canonical Wnt signaling

Canonical Wnt signaling controls -catenin protein stabilization, its translocation to the nucleus and the activation of -catenin/Tcf-4-dependent transcription. In this review, we revise and discuss the recent results describing actions of p120-catenin in different phases of this pathway. More specifically, we comment its involvement in four different steps: (i) the very early activation of CK1, essential for Dvl-2 binding to the Wnt receptor complex; (ii) the internalization of GSK3 and Axin into multivesicular bodies, necessary for a complete stabilization of -catenin; (iii) the activation of Rac1 small GTPase, required for -catenin translocation to the nucleus; and (iv) the release of the inhibitory action caused by Kaiso transcriptional repressor. We integrate these new results with the previously known action of other elements in this pathway, giving a particular relevance to the responses of the Wnt pathway not required for -catenin stabilization but for -catenin transcriptional activity. Moreover, we discuss the possible future implications, suggesting that the two cellular compartments where -catenin is localized, thus, the adherens junction complex and the Wnt signalosome, are more physically connected that previously thought.