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

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.

Apoptosis of human luteinized granulosa cell via change of mitochondria / 대한산부인과학회잡지

OBJECTIVE: To determine the effects of extracellular ATP on mitochondrial function and apoptosis during human luteinized granulosa cell cultures. METHODS: The addition of various concentrations of ATP (0, 0.1, 0.25, 0.5, 0.75 mM) 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: Measurement by patch clamp of the granulosa cell membrane potential after ATP addition to cultured granulosa cells showed that both the inward and outward currents were expressed. After treatment of the granulosa cells with JC-1, measurement of the mitochondrial activity by confocal microscopy showed that the with increasing concentrations of ATP the relative ratio of undamaged mitochondria (red/green ratio) tended to decrease (P=0.027). After double staining of the cultured granulosa cells with Annexin V and Propidium Iodide, quantitative flow cytometry analysis showed that apoptosis increased with increasing concentrations of ATP (7.88%, 8.44%, 11.40%, 13.52%, 18.57%). CONCLUSION: The results of this study shows that apoptosis of granulosa cells increases with increasing extracellular ATP concentrations in cultured human luteinized granulosa cells. This is observed to be a consequence of cell membrane purinoceptor activity and functional changes in the mitochondria. It is therefore thought that remodelling processes of the ovarian tissue is regulated by neuroendocrine factors of the extracellular ATP.