Transcription factor NFYA directs male meiotic entry by facilitating accessible chromatin at the promoters of genes expressed during meiosis [CUT&RUN]

Meiotic prophase I characterized by homologous recombination and synapsis is an intricate step for spermatogenesis. This process entails extensive changes to chromatin and transcription. Recent studies have revealed that prior to prophase I, accessible chromatin bound by paused Pol II at meiotic gene promoters is essential for their timely activation during later stages of prophase I. However, the factor responsible for promoting accessible chromatin at meiotic gene promoters before entry into prophase I is unknown. Here, we discovered that NFYA expressed in pre-meiotic germ cells promotes accessible chromatin at meiotic gene promoters. Concordantly, conditional germline deletion of Nfya in male mice blocks meiotic entry. Functionally, our spatial and single-cell ATAC-seq data revealed that loss of NFYA in pre-meiotic cells disrupts accessible chromatin at meiotic gene promoters. Our study identifies a pioneer role for NFYA in facilitating permissive chromatin at meiotic gene promoters before meiosis, thereby controlling the timely activation of meiotic genetic program during later meiosis. Overall design: CUT&RUN was performed to profile [H3K4me3 and NFYA] binding sites in FACS-sorted cells from adult testis.

以同源重组（homologous recombination）与联会（synapsis）为特征的减数分裂I期前期（Meiotic prophase I）是精子发生（spermatogenesis）过程中的复杂步骤。该进程伴随染色质（chromatin）与转录（transcription）的广泛改变。近期研究表明，在进入减数分裂I期前期之前，结合有暂停型RNA聚合酶II（paused Pol II）的开放染色质（accessible chromatin）位于减数分裂基因启动子（meiotic gene promoters）区域，其对于这些基因在减数分裂I期前期后期的适时激活至关重要。然而，在进入减数分裂I期前期之前，促进减数分裂基因启动子处开放染色质形成的调控因子仍未明确。本研究发现，在减数分裂前生殖细胞中表达的核因子Y亚基A（NFYA），可促进减数分裂基因启动子处的开放染色质形成。与之相符的是，在雄性小鼠生殖细胞中条件性敲除Nfya，会阻断其减数分裂起始进程。功能层面上，本研究的空间及单细胞ATAC-seq数据显示，减数分裂前生殖细胞中NFYA的缺失会破坏减数分裂基因启动子处的开放染色质结构。本研究阐明了NFYA在减数分裂前促进减数分裂基因启动子处形成许可性染色质的先锋功能，进而调控减数分裂后期遗传程序的适时激活。实验整体设计：本研究对成年小鼠睾丸经荧光激活细胞分选（FACS）得到的细胞，开展CUT&RUN实验以解析组蛋白H3赖氨酸4三甲基化（H3K4me3）与NFYA的结合位点谱。