Transcriptomic analysis of overexpressed SOX4 and SOX8 in TM4 Sertoli cells with emphasis on cell-to-cell...

Sertoli cells are localized in seminiferous tubules within the testis. They are the first testicular cells to differentiate during male sex determination. In the adult, Sertoli cells provide nutrients to germ cells, control factors for spermatogenesis and protection by establishing the blood-testis barrier (BTB). This BTB is composed of tight junctions, basal ectoplasmic specializations, adherent junctions and gap junctions. The transcription factor SOX8 is necessary for the maintenance of spermatogenesis during adult life whereas SOX4 is involved in developmental processes. These factors are highly expressed in Sertoli cells. However, few of their target genes in adult Sertoli cells are known. Hence, we compared the transcriptomes of TM4 Sertoli cells overexpressing or not SOX4 or SOX8 using RNA-Seq followed by pathways and networks analyses. We found that SOX4 overexpression leads to downregulated genes enriched for cell junction organization and positive regulation of cell-to-cell adhesion. Upregulated genes in response to SOX8 overexpression were enriched for Sertoli cell development and differentiation. However, downregulated genes were enriched for cell-to-cell adhesion, tight junction interactions, gap junctions' assembly, as well as extracellular matrix binding. Hence, our results confirm that SOX8 is an important mediator of Sertoli cell maturation, whereas SOX4 and SOX8 influence gene expression related to regulation of blood-testis barrier assembly. In addition, TM4 cells can be considered as a useful model to better define the regulatory mechanisms of SOX4 or SOX8 on gene transcription in Sertoli cells.