Immunocytochemical localization and expression of E-cadherin and beta-catenin in the human corpus luteum

We have previously shown that the protein connexin-43 which forms the connexons in gap junctions is present in the human corpus luteum. Abundant expression of connexin-43 is seen in the mid-luteal phase corpora lutea. Since the formation of gap junctions in a tissue requires the presence of adherens junctions formed by the cadherins, our aim in these studies was firstly to localize immunocytochemically E-cadherin and beta-catenin (a cytoplasmic protein associated with E-cadherin) in the human corpus luteum, and secondly to determine the concentrations of these proteins in the early, mid- and late luteal phase human corpora lutea. E-cadherin was localized to the periphery of luteal cells and was not detected in non-luteal tissue. beta-catenin was observed in the cytoplasm of the luteal cells. Abundant expression of E-cadherin was observed by Western analysis in the early luteal phase and the level of expression was significantly different from that observed in the mid- and late luteal phase corpora lutea. In contrast the concentrations of beta-catenin were higher in the mid-luteal phase compared to the early luteal phase. The differential expression of the cell adhesion molecule E-cadherin suggests that it may play a significant role in cell-to-cell communication in the corpus luteum, and in the cyclic development and demise of this tissue.