Dynamic expression of PGRMC1 and SERBP1 in human endometrium: an implication in the human decidualization process.

Objective: To characterize PGRMC1 and SERBP1 in human endometrium and to investigate the putative role of PGRMC1 in endometrial decidualization.

Design: The PGRMC1 and SERBP1 expression in human endometrium was determined throughout the menstrual cycle. We analyzed the colocalization of PGRMC1 and SERBP1. Then, endometrial stromal cells (ESCs) were isolated to investigate the functional effect of PGRMC1 overexpression on decidualization.

Setting: IVI clinic.

Patient(s): Endometrial biopsies were collected from fertile volunteers (n = 61) attending the clinic as ovum donors.

Intervention(s): Endometrial samples of 61 healthy fertile women.

Main Outcome Measure(s): In vivo localization of PGRMC1 and SERBP1 was assessed by immunohistochemistry. The PGRMC1/SERBP1 colocalization was investigated in vitro and in vivo. Decidualization effect of PGRMC1 overexpression was evaluated in primary ESC cultures.

Result(s): The PGRMC1 was detected in the endometrial stroma throughout the menstrual cycle, but decreased in the late secretory phase. The SERBP1 immunostaining was present in stroma and increased in the entire the menstrual cycle. The PGRMC1 and SERBP1 colocalized in the cytoplasmic fractions of nondecidualized and decidualized ESC. The PGRMC1 overexpression significantly inhibited in vitro decidualization.

Conclusion(s): Our results suggest that classic P receptors (PRs) are not the only kind playing a role in the normal physiology of the endometrium. The human decidualization process could be altered by the overexpression or mislocalization of PGRMC1 in ESC.