Follicle selection is characterized by granulosa cell differentiation and progesterone production using cholesterol. 7-dehydrocholesterol reductase (DHCR7) is the rate-limiting enzyme in cholesterol synthesis. After follicle selection, the expression of DHCR7 transcripts variants (T1, T3, and T4) significantly increase, and estrogen promotes their expression in a dose-dependent manner in chicken granulosa cells of pre-hierarchical follicles (Pre-GCs). This study investigates DHCR7's role in follicular development and selection, focusing on its mRNA and protein expression and impact on Pre-GC function, as well as histone modifications in the DHCR7 promoter region under estrogen treatment. RT-qPCR analysis revealed that the mRNA expression of total DHCR7 and its transcripts T1, T3, and T4 gradually increased as follicles developed. After follicle selection, both mRNA and protein levels of total DHCR7, along with mRNA levels of T1, T3, and T4, were upregulated. Further RT-qPCR analysis revealed that DHCR7 suppressed the expression of genes related to proliferation and apoptosis while promoting those involved in progesterone synthesis. Additionally, DHCR7 inhibited Pre-GC proliferation and apoptosis, while enhancing progesterone secretion. CUT&RUN-qPCR analysis demonstrated that estrogen significantly enriched H3K4me1, H3K4me2, H3K27ac, and H4K16ac in the estrogen response region of the DHCR7 promoter, while no significant changes were observed in H3K4me3 and H3K9ac. This study highlights the critical role of DHCR7 in follicular development and selection, demonstrating its regulation of granulosa cell differentiation and progesterone synthesis. The findings also suggest that estrogen-induced histone modifications at the DHCR7 promoter contribute to its transcriptional activation, offering new insights into the molecular mechanisms underlying ovarian function and reproductive performance in poultry.
Li et al. (Mon,) studied this question.