Vinculin Is Associated with the E-cadherin Adhesion Complex

Abstract

Cadherins mediate calcium-dependent cell-cell adhesion, and this activity is regulated by cytoplasmic interactions between cadherins, catenins, and the actinbased cytoskeleton. ␣-Catenin plays a critical role in the transmembrane anchorage of cadherins, and deletion of ␣-catenin has been shown to inactivate cadherin-mediated adhesion, resulting in a nonadhesive phenotype. Here we show that serum starvation increases E-cadherin expression and induces E-cadherin-dependent adhesion in the MDA-MB-468 breast cancer cell line. This adhesion occurred despite a lack of ␣-catenin expression, which was caused by mutations in the ␣-catenin gene. Coprecipitation analysis suggests that this adhesion may be mediated by cytoplasmic connections from cadherins to the cytoskeleton involving vinculin. A high level of vinculin associated with E-cadherin immunoprecipitates was observed in MDA-MB-468 cells. In contrast, vinculin was not detected in E-cadherin complexes in the A431 and MCF-7 epithelial carcinoma cell lines, which express ␣-catenin. However, in reciprocal immunoprecipitations using anti-vinculin antibodies, Ecadherin associated strongly with vinculin in MDA-MB-468 cells and, to a lesser extent, in A431 and MCF-7 cells. These results suggest that both ␣-catenin and vinculin may be present in the adhesion complex. To test the hypothesis that vinculin associates with E-cadherin complexes via ␤-catenin, excess recombinant ␤-catenin or ␣-catenin fusion protein was added to MDA-MB-468 cell lysates. Both specifically inhibited the coprecipitation of E-cadherin with vinculin, suggesting competition for the same binding site. These results suggest that vinculin plays a role in the establishment or regulation of the cadherin-based cell adhesion complex by direct interaction with ␤-catenin.Cadherins are calcium-dependent cell-cell adhesion molecules that mediate homotypic interactions among cells and are essential for tissue morphogenesis (for review, see Refs. 1 and 2). Adhesion via cadherins involves the coordination of extracellular binding and intracellular anchorage to the actin-based cytoskeleton. The cytoplasmic domain of E-cadherin binds to either ␤-catenin or plakoglobin/␥-catenin (for review, see , and this complex is coupled to the actin cytoskeleton by ␣-catenin, which binds to both ␤-catenin and actin (6, 7). There is evidence that ␣-catenin also binds to ␣-actinin (8, 9) and spectrin (10), but the role of these interactions in adhesion is unknown. Disruption of ␣-catenin function by genetic deletion or mutation was shown to cause a loss of E-cadherin-dependent adhesion. PC-9 lung carcinoma cells, which lack detectable ␣-catenin expression, were shown to have aberrant cell-cell adhesion (11) that was restored by transfection of these cells with ␣-catenin cDNA (12). This resulted in the establishment of a polarized epithelium and inhibition of cell growth (13). This and other work suggest that the linkage of cadherin complexes to the cytoskeleton via ␣-catenin is essential for normal cell adhesion, morphogenesis, and ...

γ-Tocotrienol suppresses prostate cancer cell proliferation and invasion through multiple-signalling pathways

“…The expression for b-catenin remains static, similar to our previous experiments using garlic derivatives (Chu et al, 2006). Although PC-3 cells do not express a-catenin, a key molecule for functional E-cadherin expression, g-T3 might restore the function of E-cadherin through other molecules such as vinculin, which has been reported to play a role in the establishment of the E-cadherinbased cell adhesion complex (Hazan et al, 1997). Taken together, our results suggest that g-T3 may suppress cancer metastasis through induction of mesenchymal -epithelial transition (MET).…”

Changing Roles of Cadherins and Catenins during Progression of Squamous Intraepithelial Lesions in the Uterine Cervix

“…This suggested that an increasing fraction of P-cadherin was involved in mediating cell-cell adhesions in high-grade SIL cells, which was possibly connected to the actin cytoskeleton via plakoglobin, which also showed a decreased solubility ( Figure 6C). In contrast to some observations published earlier, 37,38 extraction with Triton X100 extracted all cadherins from cervical keratinocytes. The pellets obtained did not contain traces of E-cadherin, as was tested in immunoblotting (not shown).…”

“…It is not absolutely clear whether the reduced amount of cellular ␣-catenin is still sufficient to provide the anchor for P-cadherin adhesions as observed in this study, or whether another molecule (ie, vinculin, relatively homologues to ␣-catenin) 50, 51 takes its place. The latter possibility was shown for some tumor cells by Hazan et al, 37 and more recently it was shown that vinculin can form a complex with ␣-catenin and thereby participate in the formation of adherens junctions. 52 However, we did not find any evidence for this in our in vitro cultures, because no vinculin was coimmunoprecipitated with E-cadherin (data not shown).…”

Wnt/beta-Catenin Signaling and Small Molecule Inhibitors

“…Changes in mutual cadherin concentrations are referred to as cadherin switches. Hence, the increase of N-cadherins against Ecadherins is a hallmark of an epithelial to mesenchymal transition (EMT) both in normal development and in metastasis [320][321][322][323]. Cadherin switches are crucial for motility, invasiveness, migration and metastasis in cancer cells [324,325].…”