Cadherin/catenin complexes in murine epidermal keratinocytes: E-cadherin complexes containing either beta-catenin or plakoglobin contribute to stable cell-cell contacts.

The cadherin/catenin complexes expressed by a murine epidermal keratinocyte cell line PDV, expressing E- and P-cadherin, have been analysed using a combination of biochemical and confocal microscopy analysis. Two types of E-cadherin complexes, containing beta-catenin or plakoglobin and alpha-catenin, were detected in PDV cells as in other cell types, while P-cadherin was mainly detected in complexes containing beta-catenin and alpha-catenin in PDV and other murine epidermal keratinocytes. Biotin-labelling studies have shown that both types of E-cadherin complexes are present at the surface of confluent cells. Furthermore, confocal microscopy analysis indicated that E-cadherin/plakoglobin complexes are located in stable cell-cell contacts at the middle lateral membranes and associated with alpha-catenin and the actin cytoskeleton, with a similar distribution to that to the E-cadherin/beta-catenin complexes. In addition, E-cadherin/plakoglobin complexes not associated with alpha-catenin or the actin cytoskeleton were detected in lower planes of the lateral contacting membranes as well as E-cadherin non-associated with catenins in the more basal planes. These studies support that in murine epidermal keratinocytes both beta-catenin- and plakoglobin-containing E-cadherin complexes contribute to the maintenance of stable cell-cell contacts and suggest a differential role of the plakoglobin containing complexes in different epithelial cell types.