Regulation of E-cadherin/Catenin association by tyrosine phosphorylation.
Alteration of cadherin-mediated cell-cell adhesion is frequently associated to tyrosine phosphorylation of p120- and beta-catenins. We have examined the role of this modification in these proteins in the control of beta-catenin/E-cadherin binding using in vitro assays with recombinant proteins. Recombinant pp60(c-src) efficiently phosphorylated both catenins in vitro, with stoichiometries of 1.5 and 2.0 mol of phosphate/mol of protein for beta-catenin and p120-catenin, respectively. pp60(c-src) phosphorylation had opposing effects on the affinities of beta-catenin and p120 for the cytosolic domain of E-cadherin; it decreased (in the case of beta-catenin) or increased (for p120) catenin/E-cadherin binding. However, a role for p120-catenin in the modulation of beta-catenin/E-cadherin binding was not observed, since addition of phosphorylated p120-catenin did not modify the affinity of phosphorylated (or unphosphorylated) beta-catenin for E-cadherin. The phosphorylated Tyr residues were identified as Tyr-86 and Tyr-654. Experiments using point mutants in these two residues indicated that, although Tyr-86 was a better substrate for pp60(c-src), only modification of Tyr-654 was relevant for the interaction with E-cadherin. Transient transfections of different mutants demonstrated that Tyr-654 is phosphorylated in conditions in which adherens junctions are disrupted and evidenced that binding of beta-catenin to E-cadherin in vivo is controlled by phosphorylation of beta-catenin Tyr-654.
Roura
S
S
Unitat de Biologia Cellular i Molecular, Institut Municipal d'Investigació Mèdica, Universitat Pompeu Fabra, C/. Dr. Aiguader 80, 08003 Barcelona, Spain.
Miravet
S
S
Piedra
J
J
García de Herreros
A
A
Duñach
M
M
D000818:Animals; D015820:Cadherins / Q000378:metabolism*; D002448:Cell Adhesion; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D051379:Mice; D010766:Phosphorylation; D011994:Recombinant Proteins / Q000378:metabolism; D015398:Signal Transduction; D015534:Trans-Activators; D014443:Tyrosine; D051176:beta Catenin
C495267:CTNNB1 protein, mouse; D015820:Cadherins; D003598:Cytoskeletal Proteins; D011994:Recombinant Proteins; D015534:Trans-Activators; D051176:beta Catenin; D014443:Tyrosine