Expression of a candidate cadherin in T lymphocytes

Abstract

Cadherins are homotypic adhesion molecules that classically mediate interactions between cells of the same type in solid tissues. In addition, E- cadherin is able to support homotypic adhesion of epidermal Langerhans cells to keratinocytes (Tang, A., Amagai, M., Granger, L. G., Stanley, J. R. and Udey, M. C. (1993) Nature (London) 361, 82-85) and heterotypic adhesion of mucosal epithelial cells to E-cadherin-negative intestinal intraepithelial T lymphocytes. Thus, we hypothesized that cadherins may play a wider role in cell-to-cell adhesion events involving T lymphocytes. We searched for a cadherin or cadherins in T lymphocytes with a pan-cadherin antiserum and antisera against α- or β-catenin, molecules known to associate with the cytoplasmic domain of cadherins. The anti-β-catenin antisera coimmunoprecipitated a radiolabeled species in T-lymphocyte lines that had a molecular mass of 129 kDa and was specifically immunoblotted with the pan- cadherin antiserum. Also, the pan-cadherin antiserum directly immunoprecipitated a 129-kDa radiolabeled species from an 125I surface- labeled Jurkat human T-cell leukemic cell line. After V8 protease digestion, the peptide map of this pan-cadherin-immunoprecipitated, 129-kDa species exactly matched that of the 129-kDa species coimmunoprecipitated with the β- catenin antiserum. These results demonstrate that T lymphocytes express a catenin-associated protein that appears to be a member of the cadherin superfamily and may contribute to T cell-mediated immune surveillance.