The transcription factor TCFL5 responds to A MYB to elaborate the male meiotic program in mice.

In male mice, the transcription factors STRA8 and MEISON initiate meiosis I. We report that STRA8/MEISON activates the transcription factors A MYB and TCFL5, which together reprogram gene expression after spermatogonia enter into meiosis. TCFL5 promotes transcription of genes required for meiosis, mRNA turnover, miR-34/449 production, meiotic exit, and spermiogenesis. This transcriptional architecture is conserved in rhesus macaque, suggesting TCFL5 plays a central role in meiosis and spermiogenesis in placental mammals. Tcfl5em1/em1 mutants are sterile, and spermatogenesis arrests at the mid- or late-pachytene stage of meiosis. Moreover, Tcfl5+/em1 mutants produce fewer motile sperm.