The Transcription Factor PRDM15 Activates the PPP2R5C / PI3K ‐Akt Pathway to Promote Steroid Hormone Secretion in Goat Granulosa Cells

ABSTRACT The proliferation and steroid hormone production capacity of granulosa cells (GCs) are critical factors in determining follicular maturation and female reproductive success. This study aims to investigate the role of PPP2R5C in regulating GC function and to reveal its upstream transcriptional regulatory mechanisms, thereby providing new molecular insights into the regulation of ovarian function. First, we examined the effects of PPP2R5C on cell proliferation and hormone secretion in a mammalian model of ovarian function: primary goat granulosa cells. We screened and validated potential transcription factors that bind to a functional single‐nucleotide polymorphism (SNP) in the PPP2R5C promoter region using bioinformatics analysis and luciferase reporter assays. A series of in vitro overexpression and interference experiments, combined with Western blot detection of key PI3K‐AKT pathway factors, then allowed us to elucidate the downstream signaling pathways of this transcriptional regulatory axis. PPP2R5C acts as a positive regulator, promoting the proliferation of granulosa cells and the secretion of estrogen and progesterone. We discovered that a mutation (G>A, rs645147899) in the PPP2R5C promoter region creates a novel binding site for the transcription factor PRDM15. The binding of PRDM15 to a mutated site on the PPP2R5C gene leads to significant upregulation of transcription. This, in turn, activates the PI3K‐AKT (particularly AKT) signaling pathway. This regulation modulates the expression of cyclin D2 and CDK4, ultimately impacting granulosa cell proliferation and steroid production. This study reveals the critical role of the PRDM15‐PPP2R5C‐AKT regulatory axis in controlling the fate of granulosa cells and their endocrine function. This mechanism may help explain individual variations in ovarian follicular development and provides new potential therapeutic targets for human reproductive disorders associated with granulosa cell dysfunction, such as polycystic ovary syndrome or premature ovarian failure.