CircSHOC2 regulates steroid hormone synthesis in ovarian granulosa cells through the mir-130b-5p/ASH1L pathway

Estrus is a critical phase in the reproductive cycle of sows and depends on normal ovarian development and steroid hormone secretion. Granulosa cells (GCs) play crucial roles in maintaining normal ovarian physiological functions in sows by secreting estradiol (E2) and progesterone (P4). CircRNAs influence steroid hormone synthesis, but their involvement in regulating gilt estrous remains unclear. In this study, circRNA sequencing was performed on the ovaries of estrus (ES) and nonestrus (NES) gilts, leading to the identification of a novel circRNA, termed circSHOC2, which is highly expressed in ES ovaries. The overexpression of circSHOC2 promoted the synthesis of E2 and P4 and increased the protein levels of key steroidogenic enzymes. Further investigation revealed that circSHOC2 acts as a sponge for miR-130b-5p. Silencing miR-130b-5p significantly enhanced E2 and P4 production, along with the upregulation of steroidogenic proteins. Additionally, miR-130b-5p was found to target ASH1 like histone lysine methyltransferase (ASH1L), with miR-130b-5p overexpression significantly inhibiting ASH1L expression. Cotransfection experiments revealed that ASH1L mitigated the inhibitory effects of miR-130b-5p on E2 and P4 synthesis in GCs. This study, through circRNA sequencing of ovaries from ES and NES gilts, revealed that circSHOC2 regulates steroid hormone synthesis in porcine GCs via the miR-130b-5p/ASH1L axis, shedding light on a potential molecular pathway involved in gilts estrus. Our results will provide molecular targets for the selection of excellent estrus sows, thereby improving the utilization rate of gilts in estrus.