Early enterocytic differentiation of HT-29 cells: biochemical changes and strength increases of adherens junctions

Abstract

We have characterized the modulation of cell–cell adhesion and the structure of adherens junctions in the human colon adenocarcinoma HT-29 cell line that differentiates into enterocytes after glucose substitution for galactose in the medium. We demonstrate that differentiated cells (HT-29 Gal) rapidly established E-cadherin-mediated interactions in aggregation assays. This effect is not due to an increase in E-cadherin expression during this early stage of cell differentiation, but rather results from the maturation of preexisting adherens junctions. These junctions are characterized by the redistribution of E-cadherin to the basolateral membrane and its co-localization with the actin cytoskeleton. Subcellular fractionation studies indicate that actin-associated E-cadherins bind β-catenin and p120 ctn. Furthermore, the p120 ctn/E-cadherin association is upregulated. These data reveal a cooperative interaction between p120 ctn and E-cadherin that corresponds to mature functional adherens junctions able to initiate tight cell–cell adhesion required for epithelium architecture and further affirm the gatekeeper role of p120 ctn.