Expression of Milk Fat Globule-EGF Factor 8 (MFGE8) in the receptive endometrium and its regulation by prolactin

FRANCHI, A; BOCA, S; OEHNINGER, S

Atlanta, Georgia

Congreso; American Society for Reproductive Medicine 65th Annual Meeting; 2009

American Society for Reproductive Medicine

OBJECTIVE: MFGE8 is a protein that participates in several cell surfacemediated regulatory events in a variety of tissues not previously linked to endometrial physiology.We have found MFGE8 mRNA up-regulated in the human endometrium during the window of implantation. Prolactin (PRL) secreted by stromal cells has been suggested to play a role modulating protein expression. Our objective was to characterize MFGE8 expression during the receptive phase and its possible regulation by PRL. DESIGN: MFGE8 expression analysis in timed human endometrial biopsies and in isolated endometrial epithelial cells (EEC). MATERIALS AND METHODS: In endometrial biopsies (proliferative and cycle days 16, 21 and 24), MFGE8 mRNA and protein expression was analyzed by real time-PCR and immunohistochemistry, respectively. In EEC, MFGE8 was localized by immunofluorescence and its protein expression was evaluated byWestern blot (n¼3) in absence or presence of PRL (0.2, 1 and 5 mg/mL). RESULTS: The immunostaining for MFGE8 in endometrial biopsies showed the protein exclusively localized to the glandular and luminal epithelium, which was confirmed byWestern blot analysis of isolated epithelial and stromal cells. The MFGE8 expression was stronger during the secretory phase and the mRNA levels were increased toward the end of the receptive period. Most of the EEC showed a diffuse staining of MFGE8 over the cytoplasmic area; however, some cells presented a punctuated staining pattern. In addition, vesicles associated to the cell surface were strongly stained. PRL treatment of EEC for 72h in vitro increased MFGE8 expression versus control (p