cAMP-induced apoptosis in granulosa cells is associated with up-regulationof P53 and bax and down-regulation of clusterin

Evidence indicates that cAMP induces apoptosis in granulosa cells of rat an d human ovary. The mechanism by which cAMP induces apoptosis is not known. This study was carried out to evaluate changes in expression of cell death promoters, P53 and bax, and cell death repressor, bcl-2, in cAMP-treated gr anulosa cells. Treatment of granulosa cells with forskolin (FSK), or 8-brom o-cAMP induced apoptosis as evidenced by internucleosomal DNA fragmentation and chromatin condensation as revealed by gel electrophoresis and fluoresc ent DAPI staining, respectively. The apoptotic effect of cAMP was accompani ed by an increase in the expression of P53 and bax proteins as evaluated by Western blot and immunocytochemistry. No change in bcl-2 protein level was observed in cAMB-treated granulosa cells as compared to control. These dat a suggest that cAMP may activate apoptosis in granulosa cells by shifting t he ratio of the death promoter to death repressor genes via alteration of P 53 and bax expression. cAMP was also shown to inhibit gene expression of cl usterin, an apoptosis-associated protein, suggesting a role for this protei n in cAMP-induced apoptosis in granulosa cells. The data of the present stu dy provide a basis fur future studies to elucidate the molecular mechanism of follicular atresia and regulation of apoptotic cell death in ovarian fol licles.