Increased adhesiveness in cultured endometrial-derived cells is related tothe absence of moesin expression

Human endometrial epithelial cells (EECs) are nonadhesive for embryos throu ghout most of the menstrual cycle. During the so-called implantation window , the apical plasma membrane of EECs acquire adhesive properties by undergo ing a series of morphological and biochemical changes. The human endometria l-derived epithelial cell line, RL95-2, serves as an in vitro model for rec eptive uterine epithelium because of its high adhesiveness for trophoblast- derived cells. In contrast, the HEC-1-A cell line, which displays poor adhe sive properties for trophoblast cells, is considered to be less receptive. The ezrin, radixin, and moesin protein family members, which are present un derneath the apical plasma membrane, potentially act to link the cytoskelet on and membrane proteins. In the present study, we have further investigate d the adhesive features in these two unrelated endometrial-derived cell lin es using an established in vitro model for embryonic adhesion. We have also analyzed the protein pattern and mRNA expression of ezrin and moesin in RL 95-2 cells versus HEC-1-A cells. The results demonstrate that RL95-2 cells were indeed more receptive (81% blastocyst adhesion) compared with HEC-1-A cells (46% blastocyst adhesion). An intermediate adhesion rate was found in primary EECs cultured on extracellular matrix gel, thus allowing a partial polarization of these cells (67% blastocyst adhesion). Furthermore, we fou nd that moesin was absent from RL95-2 cells, In contrast, ezrin is expresse d in both cell lines, yet it is reduced in adherent RL95-2 cells. Data are in agreement with the hypothesis that uterine receptivity requires down-reg ulation or absence of moesin, which is a less-polarized actin cytoskeleton.