<tex>$\alpha T$</tex>-Catenin : a novel tissue-specific <tex>$\beta$</tex>-catenin-binding protein mediating strong cell-cell adhesion
Faculty of Medicine and Health Sciences
Journal of cell science. - Cambridge
, p. 3177-3188
University of Antwerp
Cadherins are major cell-cell adhesion proteins whose cytoplasmic domains bind to catenin proteins. Strong intercellular adhesion depends on linkage of the cadherin/catenin complex to the actin cytoskeleton via alpha -catenin. To date, it is not clear how different cell types achieve the variable strength of cell-cell adhesion clearly needed in a multicellular organism. Here, we report the cloning and molecular characterization of alphaE(testis)catenin, a novel human cDNA encoding a protein with homology to both human alphaE(epithelial)-catenin and alphaN(neural)-catenin. Although originally discovered in testis, alphaT-catenin is expressed in other tissues, the highest levels being observed in heart. Immunohistochemical analysis showed human alphaT-catenin localization at intercalated discs of cardiomyocytes and in peritubular myoid cells of testis. In cells transfected with alphaT-catenin cDNA, interaction with beta -catenin was demonstrated by coimmunoprecipitation. Transfection of alpha -catenin-deficient colon carcinoma cells recruited E-cadherin and beta -catenin to cell-cell contacts and functional cadherin-mediated cell-cell adhesion was restored in this way. Moreover, compaction of these cells was at least as prominent as in the case of cells expressing endogenous alphaE-catenin. We propose that alphaT-catenin is necessary for the formation of stretch-resistant cell-cell adhesion complexes, in particular, muscle cells.