Institute of Molecular and Cell Biology, A(∗)STAR, 61 Biopolis Drive, Singapore 138673, Singapore.
Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, CONICET, Buenos Aires C1428EHA, Argentina.
Cell. 2016 Mar 24;165(1):75-87. doi: 10.1016/j.cell.2016.02.032.
Transcription factor (TF) binding to DNA is fundamental for gene regulation. However, it remains unknown how the dynamics of TF-DNA interactions change during cell-fate determination in vivo. Here, we use photo-activatable FCS to quantify TF-DNA binding in single cells of developing mouse embryos. In blastocysts, the TFs Oct4 and Sox2, which control pluripotency, bind DNA more stably in pluripotent than in extraembryonic cells. By contrast, in the four-cell embryo, Sox2 engages in more long-lived interactions than does Oct4. Sox2 long-lived binding varies between blastomeres and is regulated by H3R26 methylation. Live-cell tracking demonstrates that those blastomeres with more long-lived binding contribute more pluripotent progeny, and reducing H3R26 methylation decreases long-lived binding, Sox2 target expression, and pluripotent cell numbers. Therefore, Sox2-DNA binding predicts mammalian cell fate as early as the four-cell stage. More generally, we reveal the dynamic repartitioning of TFs between DNA sites driven by physiological epigenetic changes. VIDEO ABSTRACT.
转录因子 (TF) 与 DNA 的结合是基因调控的基础。然而，在体内细胞命运决定过程中，TF-DNA 相互作用的动力学如何变化仍然未知。在这里，我们使用光活化 FCS 来量化发育中老鼠胚胎单细胞中的 TF-DNA 结合。在囊胚中，控制多能性的 TFs Oct4 和 Sox2 在多能性细胞中比在胚胎外细胞中更稳定地结合 DNA。相比之下，在四细胞胚胎中，Sox2 与 Oct4 相比，发生更多的长寿命相互作用。Sox2 的长寿命结合在卵裂球之间变化，并受 H3R26 甲基化调控。活细胞追踪表明，那些具有更多长寿命结合的卵裂球产生更多的多能性后代，而降低 H3R26 甲基化会减少长寿命结合、Sox2 靶基因表达和多能性细胞数量。因此，早在四细胞阶段，Sox2-DNA 结合就可以预测哺乳动物细胞命运。更一般地说，我们揭示了由生理表观遗传变化驱动的 TF 在 DNA 位点之间的动态分配。视频摘要。
