Luteinizing Hormone Surge-Induced Inhibits Expression in Preovulatory Granulosa Cells.

Previous in vivo and in vitro studies have demonstrated a dramatic up-regulation of () in rat preovulatory granulosa cells (GCs) after LH/hCG treatment and its role in regulating expression during the luteal shift in steroidogenesis. In this study, we examined whether also mediates the LH-induced repression of expression in primary rat preovulatory GCs. In response to LH treatment of GCs in vitro, expression declined to less than half of its initial value by 1 h, remaining low for 24 h of culture. Overexpression of decreased basal and -induced expressions and increased progesterone secretion. Reduction of endogenous by siRNA elevated basal expression but did not affect LH-stimulated progesterone production. Overexpression of also significantly attenuated -induced promoter activity. On the other hand, mutation of the conserved Sp1/Klf binding motif in the promoter revealed that this motif is not required for -mediated repression. Taken together, these data indicate that the gene may be one of the downstream targets of , which is induced by LH in preovulatory GCs. This information may help in identifying potential targets for preventing the molecular changes occurring in hyperandrogenic disorders.