High-throughput assays of three-dimensional interactions of chromosomes have shed considerable light on the structure of animal chromatin. Despite this progress, the precise physical nature of observed structures and the forces that govern their establishment remain poorly understood. Here we present high resolution Hi-C data from early Drosophila embryos. We demonstrate that boundaries between topological domains of various sizes map to DNA elements that resemble classical insulator elements: short genomic regions sensitive to DNase digestion that are strongly bound by known insulator proteins and are frequently located between divergent promoters. Further, we show a striking correspondence between these elements and the locations of mapped polytene interband regions. We believe it is likely this relationship between insulators, topological boundaries, and polytene interbands extends across the genome, and we therefore propose a model in which decompaction of boundary-insulator-interband regions drives the organization of interphase chromosomes by creating stable physical separation between adjacent domains.

染色体三维相互作用的高通量分析为动物染色质的结构提供了可观的启示。尽管取得了这一进展，但对所观察到的结构的精确物理性质以及支配其建立的力量仍然知之甚少。在这里，我们介绍了早期果蝇的高分辨率Hi-C数据胚胎。我们证明了各种大小的拓扑结构域之间的边界映射到类似于经典绝缘子元素的DNA元素：对DNase消化敏感的短基因组区域，由已知的绝缘子蛋白强烈结合，并经常位于发散的启动子之间。此外，我们显示了这些元素与映射的多带间区域的位置之间的惊人对应关系。我们认为绝缘子，拓扑边界和多带间带之间的这种关系可能会延伸到整个基因组，因此，我们提出了一个模型，其中边界-绝缘体-带间区域的解压缩通过在相邻区域之间建立稳定的物理间隔来驱动相间染色体的组织。域。