Animal interphase chromosomes are organized into topologically associating domains (TADs). How TADs are formed is not fully understood. Here, we combined high-throughput chromosome conformation capture and gene silencing to obtain insights into TAD dynamics in Xenopus tropicalis embryos. First, TAD establishment in X. tropicalis is similar to that in mice and flies and does not depend on zygotic genome transcriptional activation. This process is followed by further refinements in active and repressive chromatin compartments and the appearance of loops and stripes. Second, within TADs, higher self-interaction frequencies at one end of the boundary are associated with higher DNA occupancy of the architectural proteins CTCF and Rad21. Third, the chromatin remodeling factor ISWI is required for de novo TAD formation. Finally, TAD structures are variable in different tissues. Our work shows that X. tropicalis is a powerful model for chromosome architecture analysis and suggests that chromatin remodeling plays an essential role in de novo TAD establishment.

动物间期染色体被组织成拓扑关联域 (TAD)。TAD 的形成方式尚不完全清楚。在这里，我们结合高通量染色体构象捕获和基因沉默来深入了解非洲爪蟾胚胎中的 TAD 动力学。一、TAD在X. tropicalis中的建立与小鼠和果蝇相似，不依赖于合子基因组转录激活。此过程之后是活性和抑制染色质隔室的进一步改进以及环和条纹的出现。其次，在 TAD 中，边界一端较高的自相互作用频率与结构蛋白 CTCF 和 Rad21 的较高 DNA 占用率相关。第三，从头形成 TAD 需要染色质重塑因子 ISWI。最后，TAD 结构在不同组织中是可变的。我们的工作表明X. tropicalis是染色体结构分析的强大模型，并表明染色质重塑在从头 TAD 建立中起着至关重要的作用。