Correlation Networks Provide New Insights into the Architecture of Testicular Steroid Pathways in Pigs.

Steroid metabolism is a fundamental process in the porcine testis to provide testosterone but also estrogens and androstenone, which are essential for the physiology of the boar. This study concerns boars at an early stage of puberty. Using a RT-qPCR approach, we showed that the transcriptional activities of several genes providing key enzymes involved in this metabolism (such as ) are correlated. Surprisingly, , a key gene for testosterone production, was absent from this group. An additional weighted gene co-expression network analysis was performed on two large sets of mRNA-seq to identify co-expression modules. Of these modules, two containing either or were further analyzed. This comprehensive correlation meta-analysis identified a group of 85 genes with as hub gene, but did not allow the characterization of a robust correlation network around . As the CYP11A1-group includes most of the genes involved in steroid synthesis pathways (including encoding for the LH receptor), it may control the synthesis of most of the testicular steroids. The independent expression of probably allows part of the production of testosterone to escape this control. This CYP11A1-group contained also and genes encoding a peptide hormone and an angiotensin peptide precursor, respectively.