RESUMO
OBJECTIVE: The present study examined the gonadotropin regulation of TR3 gene expression by luteinizing hormone (LH) in cultured human luteinized granulosa cells. METHODS: TR3 mRNA levels were detected by competitive reverse transcriptase-polymerase chain reaction (RT-PCR) method in cultured human luteinized granulosa cells collected from patients undergoing in vitro fertilization. RESULTS: TR3 transcript was transiently induced by LH, reaching maximum levels 1 hr after stimulation, in a dose-dependent manner. LH-stimulated TR3 expression was abolished by actinomycin D, but was superinduced by cycloheximide. Treatment of luteinized granulosa cells with Rp-cAMP, an inhibitor of protein kinase A, as well as, chelerythrin, an inhibitor of protein kinase C, suppressed LH-stimulated TR3 mRNA levels. In addition, forskolin and TPA mimicked the LH action on the induction of TR3 gene, implying the role of protein kinase A and C activation. CONCLUSION: Taken together, the present study demonstrates that TR3 gene was rapidly and transiently induced by LH in human luteinized granulosa cells. The results imply that TR3 may play a role in ovulation by initiating a cascade of ovulation-specific gene expression in response to LH.