HCG attenuates ATP induced apoptosis in cultured human luteinized granulosa cells (hLGCs) / 대한산부인과학회잡지

ABSTRACT

OBJECTIVE: To determine the effects of hCG on extracellular ATP induced apoptosis in cultured human luteinized granulosa cells (hLGCs) METHODS: The addition of various concentrations of ATP (0, 0.1, 0.25, 0.5, 0.75 mM) and 5 IU hCG to luteinized granulosa cells obtained during in vitro fertilization ovum pickup procedures. After culture for 24 hours, purinoceptor activity and functional changes in mitochondria were measured by patch clamp, flow cytometry, and confocal microscopy. RESULTS: Calcium imaging with fura-2 revealed that ATP elevated [Ca2+]i by mobilizing intracellularly stored Ca2+. A patch clamp study showed that ATP exerted its effect by initially binding to the P2Y type purinoceptor, as evidenced by the ATP-evoked outward Ca2+-activated K+ current. Probing mitochondria with JC-1, a mitochondrial transmembrane potential-sensitive dye, revealed that ATP induced mitochondrial depolarization in a concentration-dependent manner. A quantitative flow cytometric analysis with Annexin V showed that apoptotic cells were increased in number in proportion to the concentration of ATP, having 18.57% of apoptotic cell populations in the presence of 0.75 mM ATP compared to 7.88% in the control. Moreover, treatments with human chorionic gonadotropin (hCG) at 5 IU reversed both the ATP-induced mitochondrial depolarization and apoptosis (18.57 vs 6.32%). CONCLUSION: Taken together, these results indicate, first, extracellular ATP recognized by the P2Y type purinoceptor on h-LGCs increases the intracellular Ca2+. Second, the increased intracellular Ca2+ triggers the apoptotic cascade by acting at least, in part, on mitochondria. Third, hCG reverses the ATP-induced apoptosis, raising a possible clinical implication of hCG in the treatment of degeneration of granulosa cells such as follicular atresia.