Transcriptomic Analysis of Porcine Granulosa Cells Overexpressing Retinol Binding Protein 4

Retinol binding protein 4 (RBP4), mainly secreted by the liver and adipocytes, is a transporter of vitamin A. RBP4 has been shown to be involved in several pathophysiological processes, such as obesity, insulin resistance, and cardiovascular risk. Reports have indicated the high expression levels of RBP4 in cystic follicles. However, the role of RBP4 in mammalian follicular granulosa cells (GCs) remains largely unknown. To illustrate the molecular pathways associated with the effects of RBP4 on GCs, we used high-throughput sequencing to detect differential gene expression in GCs overexpressing RBP4. A total of 113 differentially expressed genes (DEGs) were identified in RBP4-overexpressing GCs, and they included 71 upregulated and 42 downregulated genes. The differential expressions of the top 10 DEGs were further confirmed by real-time quantitative polymerase chain reaction. Pathway analysis indicated that the DEGs are mostly involved in oxidative phosphorylation, Parkinson's disease, non-alcoholic fatty liver disease, Huntington's disease, cardiac muscle contraction, Alzheimer's disease, fatty acid biosynthesis, AMP-activated protein kinase signaling pathway, and insulin signaling pathway. Genes in these pathways should be useful for future studies on GCs. Altogether, the results of our study establish a framework for understanding the potential functions of RBP4 in porcine GCs.