The circadian system performs an important role in mammalian reproduction with significant effects on hormone secretion. Nuclear receptor subfamily 1 group D member 1 (NR1D1) functions as a transcriptional repressor in the circadian system and affects granulosa cells (GCs), but how it regulates estrogen synthesis has not been clarified. We investigated the effect of NR1D1 on estrogen synthesis and found that NR1D1 was highly expressed in GCs, mainly in cell nuclei. Additionally, the expression of NR1D1 and estrogen synthesis key genes CYP19A1, CYP11A1 and StAR showed rhythmic changes in porcine ovarian GCs. Activation of NR1D1 enhances its ability to inhibit the transcriptional activity of CYP19A1 by binding to the RORE on the CYP19A1 promoter, resulting in a decrease in estradiol content. Interference with NR1D1 can eliminate the transcriptional inhibition of CYP19A1 and promote the synthesis of estradiol. The results suggest that the hormone secretion of the ovary itself is also regulated by the biological clock, and any factors that affect the circadian rhythm can affect the endocrine and reproductive performance of sows, so the natural rhythm of sows should be maintained in production.
Keywords: Biological clock system; Estrogen synthesis; Granulosa cell; NR1D1.
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