Control of ciliary transcriptional programs during spermatogenesis  by antagonistic transcription factors
Cilia and flagella are dynamicallyregulatedduring development and differentiation.  Coordination of temporal and spatial transcription regulators are essential for ciliogenesis. We here report that XAP5 and XAP5L are two conserved pairs of antagonistic transcription regulators that control ciliary transcriptional programs during spermatogenesis. Male mice lacking either XAP5 or XAP5L display infertility, as a result of meiotic prophase arrest and sperm cilia malformation, respectively. XAP5 positively regulates the ciliary gene expression by activating the key regulators including FOXJ1 and RFX families during the early stage of spermatogenesis. In contrast, XAP5L negatively regulates the expression of ciliary genes via repressing these ciliary transcription factors during the spermiogenesis stage. Taken together, our data provide new insights into the mechanisms by which temporal and spatial transcription regulators are coordinated to control ciliary transcriptional programs during spermatogenesis. Overall design: To investigate the XAP5L-dependent genes during sperm cilia assembly, we generated XAP5L KO mice using CRISPR/CAS9 system and then performed RNA-seq analysis using postnatal day 56 (D56)  mature sperm collected from the cauda epididymis of WT and XAP5L KO adult mice. To investigate the roles of XAP5 during spermatogenesis, we generated XAP5 male germ cell conditional KO (cKO) mice using XAP5 floxed mice mating with Stra8-EGFPCre mice, and then performed RNA-seq analysis using D16 WT and XAP5 cKO testes samples. Three biological replicates were included for each genotype.