Transitions in cell potency during early mouse development are driven by Notch

The Notch signalling pathway plays fundamental roles in diverse developmental processes in metazoans, where it is important in driving cell fate and directing differentiation of various cell types. However, we still have limited knowledge about the role of Notch in early preimplantation stages of mammalian development, or how it interacts with other signalling pathways active at these stages such as Hippo. By using genetic and pharmacological tools in vivo, together with image analysis of single embryos and pluripotent cell culture, we have found that Notch is active from the 4-cell stage. Transcriptomic analysis in single morula identified novel Notch targets, such as early naive pluripotency markers or transcriptional repressors such as TLE4. Our results reveal a previously undescribed role for Notch in driving transitions during the gradual loss of potency that takes place in the early mouse embryo prior to the first lineage decisions. Transcriptomic analysis comparing single Rbpj mutant and control mouse morulae. RNA was isolated from individual E2.5 embryos from two litters. 3 mutant and 3 control embryos were used for analysis.Notch信号通路（Notch signalling pathway）在后生动物（metazoans）的多种发育过程中发挥核心作用，其在调控细胞命运决定与多种细胞类型的分化方向上具有关键意义。然而，目前学界对于Notch在哺乳动物发育早期植入前阶段的作用，以及其与该阶段活跃的其他信号通路（如Hippo信号通路）的互作机制仍知之甚少。本研究通过在体使用遗传学与药理学工具，结合单胚胎影像分析及多能细胞培养实验，发现Notch信号通路早在4细胞阶段即已激活。对单个桑葚胚的转录组分析鉴定出了全新的Notch通路靶基因，例如早期初始多能性标记物，或是TLE4这类转录抑制因子。本研究结果揭示了Notch信号通路此前未被报道的功能：在小鼠早期胚胎首次谱系决定之前，其参与调控细胞潜能逐步丧失过程中的状态转变。本研究开展了对比单个Rbpj突变型与野生型对照小鼠桑葚胚的转录组分析：实验从两窝E2.5期单个胚胎中分离RNA，共使用3个突变型胚胎与3个对照胚胎完成分析。