RNA-seq analysis of the biological process and regulatory signal of TGF-β1-mediated changes in ovarian granulosa cells in small-tail Han sheep

Transforming growth factor beta-1 (TGF-β1) regulates the proliferation of ovarian granulosa cells and participates in follicular development in small-tail Han sheep via the SMAD pathway. However, which additional biological processes and regulatory mechanisms are involved in TGF-β1-mediated regulation of granulosa cell changes remains unknown. In this study, TGF-β1-treated (10 ng/mL) ovarian granulosa cells of small-tail Han sheep were used as the model, RNA-Seq was employed to screen differentially expressed genes (DEGs), and rescue experiments were used to verify selected key pathways. In total, 1179 upregulated and 873 downregulated DEGs were screened using RNA-Seq. Gene Ontology (GO) enrichment analysis showed that the DEGs were mainly involved in the biological processes of cell adhesion, cell migration, cell cycle, cell proliferation and apoptosis, and endocrine regulation. Meanwhile, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis indicated that the DEGs were primarily associated with pathways relating to ECM-receptor interaction, PI3K-AKT, focal adhesion, MAPK, TNF, and FOXO signaling, among others. The addition of doramapimod confirmed that the p38 pathway participates in the TGF-β1-induced proliferation and apoptosis of ovarian granulosa cells as well as the regulation of steroid hormone secretion. These results revealed a novel TGF-β1/p38 pathway-mediated mechanism that induces both the proliferation and apoptosis of ovarian granulosa cells. Our findings provide a basis for better understanding the genetic mechanism of TGF-β1 action in follicle development.