Department of Biology, Emory University, Atlanta, GA, USA.
Nat Rev Genet. 2018 Dec;19(12):789-800. doi: 10.1038/s41576-018-0060-8.
Studies of 3D chromatin organization have suggested that chromosomes are hierarchically organized into large compartments composed of smaller domains called topologically associating domains (TADs). Recent evidence suggests that compartments are smaller than previously thought and that the transcriptional or chromatin state is responsible for interactions leading to the formation of small compartmental domains in all organisms. In vertebrates, CTCF forms loop domains, probably via an extrusion process involving cohesin. CTCF loops cooperate with compartmental domains to establish the 3D organization of the genome. The continuous extrusion of the chromatin fibre by cohesin may also be responsible for the establishment of enhancer-promoter interactions and stochastic aspects of the transcription process. These observations suggest that the 3D organization of the genome is an emergent property of chromatin and its components, and thus may not be only a determinant but also a consequence of its function.
3D 染色质组织的研究表明，染色体是按照层次组织的，形成由较小的结构域组成的大隔室，这些小的结构域被称为拓扑关联结构域（TAD）。最近的证据表明，隔室比之前认为的要小，转录或染色质状态负责导致所有生物体中形成小隔室结构域的相互作用。在脊椎动物中，CTCF 通过涉及黏连蛋白的外推过程形成环结构域。CTCF 环与隔室结构域合作，建立基因组的 3D 组织。黏连蛋白通过不断挤压染色质纤维也可能负责建立增强子-启动子相互作用和转录过程的随机方面。这些观察结果表明，基因组的 3D 组织是染色质及其成分的一种涌现特性，因此它不仅是功能的决定因素，也是功能的结果。
