Effect Of UPA On Proliferation And Apoptosis Of Bovine Cumulus-granulosa Cells Cultured In Vitro

Urokinase type plasminogen activator original and its receptor (uPA/uPAR system) has the important roles in the normal and abnormal physiology and reproductive activity. But it has been rarely reported for uPAR expression in bovine follicular cells and the significance and function of uPA expression in bovine COCs (cumulus-oocyte complexes) during in vitro maturation. In This study, by using several methods,including cell immunofluorescence,culture, proliferation apoptosis cell cycle detection technologies,uPA and uPAR expression and their possible interaction mechanism in the process of bovine cumulus granulosa cell proliferation and apoptosis are discussed. The results showes that uPA and uPAR proteins are expressed in bovine cumulus granulosa cells; 0.5 ng/mL uPA and 1μg/mL Amiloride (uPA inhibitor) could significantly increase or inhibit cell proliferation; At 48 h and 72 h of in vitro culture, uPA could significantly promote cell proliferation, while uPAR antibody added significantly blockes the effect of uPA on bovine cumulus granulosa cell proliferation; Amiloride and uPAR antibody could significantly increase in S and G2/M phase cell ratio, and has no effect on cell apoptosis. This study concludes that uPA expressed by bovine cumulus granulosa cells through an autocrine pathway, combines with its recepter uPAR anchored in cell membrane, then promotes cumulus granulosa cell proliferation. After uPA activity inhibited by Amiloride or uPAR function blocked by its antibody, the cell proliferation promoted by uPA is inhibited, which could be related to cells blocked at G2-M or anaphase checkpoints,and has nothing to do with cell apoptosis. These results will be helpful to further understand the mechanism of bovine follicular development and atresia.