Large-scale transcriptomic analyses reveal downstream target genes of ZFY1 and ZFY2 transcription factors in male germ cells
The mouse zinc finger genes Zfy1 and Zfy2 are essential for male fertility. Recently, we produced Zfy1 knock-out (KO), Zfy2 KO, and Zfy1/2 double-knock-out (Zfy DKO) mice, and found that Zfy DKO males were infertile. The mechanism by which ZFY contributes to reproduction remains unknown but based on predicted protein sequence and in vitro assays we hypothesize that it controls expression of genes essential for spermatogenesis. To identify which genes ZFY regulates, we performed comparative transcriptome analysis of sorted male germ cells at three different spermatogenesis stages from three Zfy KO models and control wild-type males. Significantly altered germ cell transcriptomes were identified with Zfy2 KO and Zfy DKO. Analyses of differentially expressed genes supported that Zfy loss altered spermatogenesis, DNA packaging/chromatin organization, and apoptosis pathways. Alternative splicing was deregulated in Zfy KO models, affecting sperm function and chromatin regulation pathways. In support of in-silico findings, Zfy DKO males were shown to have impaired sperm chromatin organization, functional sperm deficiencies, and increased germ cell apoptosis. ZFY regulation of apoptotic pathways was demonstrated also in transfected human cells. We conclude that Zfy is a critical regulator of meiosis and spermiogenesis in addition to its previously described function as a cell-cycle regulator. Overall design: We generated mice with knockout of Y chromosome genes Zfy1 (Zfy1, KO), Zfy2 (Zfy2 KO) and both Zfy1 and Zfy2 (Zfy DKO). As as control we used wild-type XY males (WT). All males were on C57BL/6 genetic background. We FACs-purified primary spermatocytes (SC1), secondary spermatocytes (SC2) and round spermatids (RS) from Zfy1 KO, Zfy2 KO, Zfy DKO and XY and performed RNA-seq.