Role of secreted frizzled-related protein 5 in granulosa cells of hu sheep ovaries.

ABSTRACT

The objective of this study was to examine the expression patterns of secreted frizzled-related protein 5 (SFRP5) in the ovaries of Hu sheep and to explore the key downstream factors of SFRP5 in sheep granulosa cells (GCs) using RNA-seq. In the present study, SFRP5 was widely expressed in the ovary and localized to GCs and oocytes during various stages of follicular development. In addition, the expression of SFRP5 increased with follicular diameter. In contrast to the negative control, SFRP5 knockdown promoted the EdU-positive cell rate with an increase in PCNA mRNA and protein levels, whereas SFRP5 overexpression had the opposite effect. In addition, the cell cycle was propelled from the G0/G1 phase to the S phase with the upregulation of CCNB1, CCND1, CDK1, and CDK4 after SFRP5 knockdown. Moreover, SFRP5 overexpression enhanced the apoptosis of GCs with increased Caspase3 protein levels. Following SFRP5 knockdown, differentially expressed genes were mainly enriched in the PI3K/AKT, MAPK, Wnt, and Hippo signaling pathways, and several related candidate genes such as MMP1, MMP3, SFRP4, INHA, TGFA, and CASP3 were screened. In general, this study enhances our understanding of the expression of SFRP5 in the GCs of Hu sheep, along with its functions in follicular development.