An Octapeptide in the Juxtamembrane Domain of VE-cadherin is Important for P120ctn Binding and Cell Proliferation

The cadherins are a family of adhesive proteins involved in cell-cell homophilic interactions. VE-cadherin, expressed in endothelial cells, is involved in morphogenesis, regulation of permeability, and cellular proliferation. The cytoplasmic tails of cadherins contain two major domains, the juxtamembrane domain that plays a role in the intercellular localization of the protein and also serves for binding of p120ctn, and a C-terminal domain that associates with beta- or gamma-catenin. A highly conserved region present in the juxtamembrane domain of the cadherins has been shown to be necessary for p120ctn binding in E-cadherin. Using a mutant VE-cadherin lacking a highly conserved octapeptide, we demonstrated that it is required for p120ctn binding to VE-cadherin as determined by immunoprecipitation and colocalization studies. By immunofluorescence, this mutant protein has a topographical distribution similar to that of the wild-type VE-cadherin and, therefore, we conclude that the topographical distribution of VE-cadherin is independent of this motif. In addition, although cell-cell association is present in cells expressing this mutant form of VE-cadherin, we found that the strength of adhesion is decreased. Finally, our results for the first time demonstrate that the interaction of VE-cadherin with p120 catenin plays an important role in cellular growth, suggesting that the binding of p120 catenin to cadherins may regulate cell proliferation.