POSTN promotes granulosa cell proliferation in sheep follicles through focal adhesion

Background The complex regulatory mechanisms involved in follicular development in sheep are not fully understood. This study aimed to understand the expression of periostin (POSTN) in granulosa cells (GCs) and its effect on follicle development.Methods GCs of follicular with different diameters were harvested from follicle-stimulating hormone (FSH) injected and noninjected adult and lambs for transcriptome sequencing experiments. Differentially expressed genes (DEGs) related to follicle development were identified by bioinformatics analysis. The effect of luteinizing hormone (LH) treatment on POSTN expression in GCs was examined. POSTN was overexpressed or inhibited in GCs, and its effects on cell proliferation and apoptosis, as well as potential mechanisms of action, were evaluated.Results Common DEGs were identified between adult sheep and lambs, as well as large and small follicles. It was found in the constructed coexpression network and protein-protein interaction network that POSTN might be involved in follicle development and related to focal adhesion. POSTN showed higher expression in ovarian tissue than in other tissues and higher expression in large follicles than in small follicles. LH treated GCs promoted POSTN expression. Overexpression of POSTN in GCs significantly increased cell proliferation and inhibited apoptosis. Phosphorylation levels of focal adhesion kinase were elevated in POSTN overexpressing GCs.Conclusion POSTN affects GCs proliferation and follicle development through the focal adhesion, potentially improving fecundity in sheep.