Specific Phosphorylation of p120-Catenin Regulatory Domain Differently Modulates Its Binding to RhoA

Abstract

p120-catenin is an adherens junction-associated protein that controls E-cadherin function and stability. p120-catenin also binds intracellular proteins, such as the small GTPase RhoA. In this paper, we identify the p120-catenin N-terminal regulatory domain as the docking site for RhoA. Moreover, we demonstrate that the binding of RhoA to p120-catenin is tightly controlled by the Src family-dependent phosphorylation of p120-catenin on tyrosine residues. The phosphorylation induced by Src and Fyn tyrosine kinases on p120-catenin induces opposite effects on RhoA binding. Fyn, by phosphorylating a residue located in the regulatory domain of p120-catenin (Tyr112), inhibits the interaction of this protein with RhoA. By contrast, the phosphorylation of Tyr217 and Tyr228 by Src promotes a better affinity of p120-catenin towards RhoA. In agreement with these biochemical data, results obtained in cell lines support the important role of these phosphorylation sites in the regulation of RhoA activity by p120-catenin. Taken together, these observations uncover a new regulatory mechanism acting on p120-catenin that contributes to the fine-tuned regulation of the RhoA pathways during specific signaling events.

SUPPLEMENTAL MATERIAL

We especially thank Neus Ontiveros for technical assistance.

This study was supported by grants awarded by the Spanish Ministerio de Ciencia y Tecnología (BMC2003-00410 and BFU2006-03203 to M.D. and SAF2003-02324 and SAF2006-00339 to A.G.H.). Funding by Generalitat de Catalunya (2005SGR00970) is also appreciated. G.S., I.R., J.C., D.C., and P.V. were recipients of predoctoral fellowships awarded by DGR-UAB (Generalitat de Catalunya) (to G.S.), Instituto de Salud Carlos III (Ministerio de Sanidad) (to I.R.), and Ministerio de Educación y Ciencia (to J.C., D.C., and P.V.).