P2y(6) Purinergic Receptor Regulates Steroid Synthesis And Proliferation Of Ovarian Luteal Cells

Aim: As an important messenger, Uridine 5'-diphosphate (UDP) is involved in series of physiological and pathological processes through activating P2Y(6) purinergic receptor. However, the detailed function and possible mechanism of P2Y(6) in ovarian luteal cells remain unclear. Methods: Primary murine luteal cells were isolated and cultured. CCK-8 assay was employed to analyze the cell viability after P2Y(6) agonist (UDP) and P2Y(6) selective antagonist (MRS2578) treatment. Radioimmunoassay was used to assess the progesterone and estradiol production. The expression of three essential steroidogenic enzymes, including the p450 cholesterol side-chain cleavage enzyme (CYP11A), 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) and steroidogenic acute regulatory protein (StAR) were examined by Western blotting. We also examined the ERK1/2 phosphorylation level and the expression of steroidogenic factor 1 (SF1). Results: We found that P2Y(6) was highly expressed in murine luteal cells. UDP decreased the progesterone secretion and MRS2578 rescued the effect of UDP. Further studies showed that CYP11A, 3 beta-HSD and StAR were regulated by UDP. UDP treatment also decreased ERK1/2 phosphorylation, concomitant with decreased expression of SF1, while MRS2578 treatment relieved the effect of UDP. Conclusions: In conclusion, this study demonstrated for the first time that UDP/P2Y(6) purinergic signaling regulated progesterone secretion by inhibiting the expression of CYP11A, 3 beta-HSD and StAR in luteal cells. The ERK1/2 MAPK signaling and downstream SF1 may contribute to the process.