Functional Roles of Eph A-Ephrin A1 System in Endometrial Luminal Epithelial Cells During Early Pregnancy

Eph and ephrin regulate diverse biological events such as proliferation, adhesion, migration, and angiogenesis through cell-to-cell interactions. However, little is known of their functional role and mechanisms of action in uterine endometrial cells. In the present study, we demonstrated the effects of the Eph and ephrin on interactions between blastocysts and endometrial luminal epithelial (pLE) cells in the pig that is regarded as an excellent biomedical animal model for research on the peri-implantation period of pregnancy. Results of this study indicated that among eight members of the Eph A family, expression of Eph A1, A2, A4, and A7 was strongly detected in endometrial epithelial cells during early pregnancy. Of these, for identification of signal transduction pathways induced by ephrin A1, a major ligand for Eph A, cell proliferation assays, and immunofluorescence and cell cycle regulation were analyzed following treatment of pLE cells with ephrin A1. Ephrin A1 stimulated proliferation of pLE cells as evidenced by abundant PCNA expression and an increase in the G2/M phase. Western blot analysis showed that ephrin A1 activated PI3K and MAPK signaling proteins in a time-dependent manner. Moreover, phosphorylation of AKT, ERK1/2, P38, and JNK proteins were suppressed by their inhibitors wortmannin, U0126, SB203580, and SP600125, respectively. Also, phosphor-AKT was reduced by ERK1/2 and P38 inhibitors. Ephrin A1-induced proliferation and migration of pLE cells was also blocked by those inhibitors. Collectively, these results suggest that ephrin A1 enhances interactions between porcine blastocysts and endometrial luminal epithelial cells by activating PI3K and MAPK signal transduction pathways. J. Cell. Physiol. 232: 1527-1538, 2017. © 2016 Wiley Periodicals, Inc.