Abstract: Objective： Orphan nuclear receptor NR4A1， a member of the nuclear receptor superfamily，is widely expressed in different cell types and mediates diverse biological processes. In the present study，our main purpose was to explore the function of NR4A1 in the transcript regulation of steroidogenic enzyme genes responsible for ovarian theca cell steroidogenesis. Methods： We constructed recombinant adenovirus AdCMV?-NR4A1 and AdH1-NR4A1 to enhance or knockdown the expression of NR4A1 in theca cells，respectively. The expression patterns of Cyp11a1， Cyp17a1 and Hsd3b2 were subsequently analyzed by real?-time RT-PCR. Moreover，concentrations of testosterone in the spent medium were measured by radioimmunoassay. Results：Our results show that overexpression of NR4A1 in theca cells stimulates the expression of Star， Cyp11a1， Cyp17a1 and Hsd3b2， leading to increased testosterone production. Conversely，knockdown of the endogenous NR4A1 exhibits a significant decrease in Cyp11a1， Cyp17a1 and Hsd3b2 expression and testosterone production. Forskolin（FSK）， an activator of cAMP/PKA pathway，was applied to the cultured follicles. FSK rapidly increases the Nr4a1 mRNA levels followed by an increase in Cyp11a1， Cyp17a1 and Hsd3b2. Conclusions：Collectively， our results outline a previously unrecognized role for NR4A1 in the transcriptional regulation of Cyp11a1， Cyp17a1 and Hsd3b2 in ovarian theca cells. Modulation of these steroidogenic enzymes by NR4A1 could influence the capacity of the ovarian theca cells to produce androgen. This study provide basis for us to further explore the mechanism of NR4A1 on the pathophysiology development of polycystic ovary syndrome hyperandrogenism at molecular level.

Key words: Nuclear receptor NR4A1, Polycystic ovary syndrome, Hyperandrogenism