title: 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 actin-based cytoskeleton. alpha-Catenin plays a critical role in the transmembrane anchorage of cadherins, and deletion of alpha-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 alpha-catenin expression, which was caused by mutations in the alpha-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 alpha-catenin. However, in reciprocal immunoprecipitations using anti-vinculin antibodies, E-cadherin 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 alpha-catenin and vinculin may be present in the adhesion complex. To test the hypothesis that vinculin associates with E-cadherin complexes via beta-catenin, excess recombinant beta-catenin or alpha-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 beta-catenin.
authors.affiliation: Department of Surgery, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA.
authors.forename: R B
authors.initials: RB
authors.lastname: Hazan
authors.forename: L
authors.initials: L
authors.lastname: Kang
authors.forename: S
authors.initials: S
authors.lastname: Roe
authors.forename: P I
authors.initials: PI
authors.lastname: Borgen
authors.forename: D L
authors.initials: DL
authors.lastname: Rimm
mesh_terms: D000595:Amino Acid Sequence; D015820:Cadherins / Q000378:metabolism*; D002448:Cell Adhesion; D016895:Culture Media, Serum-Free; D003598:Cytoskeletal Proteins / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D011485:Protein Binding; D014407:Tumor Cells, Cultured; D016596:Vinculin / Q000378:metabolism*; D051178:alpha Catenin
chemical_list: C495273:CTNNA1 protein, human; D015820:Cadherins; D016895:Culture Media, Serum-Free; D003598:Cytoskeletal Proteins; D051178:alpha Catenin; D016596:Vinculin