Roles of Stra8 and Tcerg1l in retinoic acid induced spermatogonial differentiation in mouse.

Retinoic acid (RA) induces spermatogonial differentiation, but the mechanism by which it operates remains largely unknown. We developed a germ cell culture assay system to study genes involved in spermatogonial differentiation triggered by RA. Stimulated by Retinoic Acid 8 (Stra8), an RA-inducible gene, is indispensable for meiosis initiation, and its deletion results in a complete block of spermatogenesis at the pre-leptotene/zygotene stage due to failure to complete pre-meiotic DNA replication. To interrogate the role of Stra8 in RA mediated differentiation of spermatogonia, we derived germ cell cultures from the neonatal testis of both wild type and Stra8 knock-out mice. We provide the first evidence that Stra8 plays a crucial role in modulating the responsiveness of undifferentiated spermatogonia to RA and facilitates transition to a differentiated state. Stra8-mediated differentiation is achieved through downregulation of a large portfolio of genes and pathways, most notably including genes involved in the spermatogonial stem cell self-renewal process. We also report here for the first time the role of Transcription Elongation Regulator-1 Like (Tcerg1l) as a downstream effector of RA-induced spermatogonial differentiation. Overall design: Cultured germ cells of WT and Stra8-KO genotype were treated with DMSO (control) or retinoic acid (RA) for 4, 8 or 24 hours along with 0h untreated samples. mRNA was extracted from three replicates of each treatment/time point and sequenced.