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

Estrus represents a critical phase in the porcine reproductive cycle and relies on functional ovarian development and coordinated steroidogenesis. Granulosa cells (GCs) mediate these processes by secreting estradiol (E₂) and progesterone (P₄), which are essential for follicular maturation and ovulatory competence. While circular RNAs (circRNAs) have been implicated in steroid hormone synthesis, their involvement in the regulation of gilt estrous remains unclear. In this study, circRNA sequencing was performed on ovarian tissues of estrus (ES) and non-estrus (NES) gilts, resulting in the identification of a novel circRNA, termed circular SHOC2 leucine rich repeat scaffold protein (circSHOC2), which exhibited marked up-regulation in ES ovaries. Functional assays demonstrated that circSHOC2 overexpression enhanced E₂ and P₄ synthesis and increased the protein levels of key steroidogenic enzymes. Mechanistic investigation revealed that circSHOC2 sponges miR-130b-5p. Silencing miR-130b-5p significantly enhanced E₂ and P₄ production, along with the up-regulation of steroidogenic proteins. Additionally, miR-130b-5p targeted ASH1-like histone lysine methyltransferase (ASH1L), while its overexpression significantly inhibited ASH1L. Cotransfection experiments revealed that ASH1L mitigated the inhibitory effects of miR-130b-5p on E₂ and P₄ synthesis in GCs. These findings establish a regulatory axis in which circSHOC2 modulates steroidogenic capacity in porcine GCs via the miR-130b-5p/ASH1L pathway, offering mechanistic insight into the molecular basis of gilt estrus and providing potential targets to enhance reproductive efficiency.