SLIC-CAGE (Super-Low Input Carrier-CAGE) transcription start site mapping of mouse migratory and gonadal primordial germ cells, postnatal oocytes and early embryo

We used SLIC-CAGE to map transcription start sites (TSSs) of mouse primordial germ cells from embryonic days 9.5-16.5, postnatal oocytes (P6, P14 and MII), and early 2-cell and 4-cell mouse embryos. We use this TSS data to show that the mouse germline development starts with the somatic promoter code with a prominent switch to the maternal code (W-box dependent) occurring during the follicular oogenesis. We also find that the promoters of gonadal germ cells are characterised by a previously unknown divergence from the somatic transcription initiation. This divergence is distinct from the promoter code used later by the developing oocytes and reveals genome-wide promoter remodelling during early female and male germline development.我们利用SLIC-CAGE技术，绘制了胚胎日龄9.5至16.5的小鼠原始生殖细胞、产后卵母细胞（P6、P14及MII期）以及早期2细胞、4细胞小鼠胚胎的转录起始位点（transcription start sites, TSSs）图谱。基于该TSS数据集，我们证实小鼠生殖系发育初始以体细胞启动子编码为基础，在卵泡卵子发生过程中会发生显著转变，切换至依赖W-box的母本编码。此外我们还发现，性腺生殖细胞的启动子存在此前未被报道的、与体细胞转录起始模式的差异；该差异与后续发育卵母细胞所采用的启动子编码截然不同，同时揭示了雌性与雄性早期生殖系发育过程中全基因组范围内的启动子重塑事件。