Transcriptome profiling of equine ovarian cortex during foetal and adult stages

Abstract

AbstractThe equine foetal ovary has some unique characteristics that differ from other animals, such as ovary hyperplasia and high oestrogen secretion, and inverted location of cortex and medulla present in adult mare. The ovarian cortex supports the process of folliculogenesis and development, the synthetics and expression of oestrogen; however, the character‐related molecular mechanisms and specific biological functions in equine foetal ovarian cortex are still poorly understood. To explore the associated regulatory networks and molecular events of equine foetal ovary during the hyperplasia stage, we analysed the transcriptomic differences between the equine second‐trimester foetal ovarian cortex and adult ovarian cortex by RNA‐seq. There were 6334 differentially expressed genes (DEGs) present in foetal vs. adult, of which 3234 and 3100 DEGs were upregulated and downregulated, respectively. GO and KEGG were used for functional and pathway enrichment analysis of the DEGs. In particular, we found that some DEGs with high fold changes were related to steroid production and metabolism, such as CYP11A1, CYP17A1, LDLR, STAR and SCARB1, which were in line with the efficient oestrogen production in the equine foetal ovary. The transcriptome profile revealed the functional and developmental characteristics and gene expression patten of the ovarian cortex in the foetal and adult stages of the mare. Our study provides new insights into the molecular mechanism of equine second‐trimester foetal ovarian development through transcriptome analysis and provides insights for improving care or treatment for the pregnant mare and the foetus.