Ovulatory signal-triggered chromatin remodeling in ovarian granulosa cells by HDAC2 phosphorylation activation-mediated histone deacetylation

Abstract

Background Epigenetic reprogramming is involved in luteinizing hormone (LH)-induced ovulation; however, the underlying mechanisms are largely unknown. Results We here observed a rapid histone deacetylation process between two waves of active transcription mediated by the follicle-stimulating hormone (FSH) and the LH congener human chorionic gonadotropin (hCG), respectively. Analysis of the genome-wide H3K27Ac distribution in hCG-treated granulosa cells revealed that a rapid wave of genome-wide histone deacetylation remodels the chromatin, followed by the establishment of specific histone acetylation for ovulation. HDAC2 phosphorylation activation coincides with histone deacetylation in mouse preovulatory follicles. When HDAC2 was silenced or inhibited, histone acetylation was retained, leading to reduced gene transcription, retarded cumulus expansion, and ovulation defect. HDAC2 phosphorylation was associated with CK2α nuclear translocation, and inhibition of CK2α attenuated HDAC2 phosphorylation, retarded H3K27 deacetylation, and inactivated the ERK1/2 signaling cascade. Conclusions This study demonstrates that the ovulatory signal erases histone acetylation through activation of CK2α-mediated HDAC2 phosphorylation in granulosa cells, which is an essential prerequisite for subsequent successful ovulation.

Cellular atlas of the human ovary using morphologically guided spatial transcriptomics and single-cell sequencing

“…Likewise, the list of granulosa-specific genes included canonical marker genes HSD17B1, INHBB, FOXL2, and AMH and the recently reported TNNI3, MAGED2, CD99, SERPINE2, CDH2, and BEX1 (9, 13), along with many histone protein-coding genes (data S5), which have not been reported for granulosa cells. However, numerous studies have suggested that proliferating granulosa cells undergo large-scale epigenetic change during late folliculogenesis, partly driven by gonadotrophins such FSH (40)(41)(42)(43). The list also included genes involved in granulosa cell-oocyte signaling, such as the transzonal projection-related genes FSCN1 and MYO10, and the tetraspanin protein gene TSPAN7, which is involved in extracellular vesiclemediated signaling between granulosa cells and the oocyte (44,45).…”

“…Target enrichment ROIs were segmented into AOIs based on staining for CD68, Ki67, SMA, DAZL, and PGR. To collect concentric ROIs from ovarian follicles, a mask was designed in ImageJ (40) and imposed on the follicle's region in the tissue.…”