ABSTRACT
Mammalian genomic DNA in the cell nucleus doesn't exist in linear form but is highly folded and condensed into chromatin with a three-dimensional (3D) structure possessing a specific spatial structure and conformation. Hi-C, the high-throughput chromosome conformation capture technology, was first published in 2009, and it provides an in-depth view of 3D genomics. According to the size of DNA unit, the 3D hierarchical units of mammalian genome can be categorized sequentially as chromosome territory (CT), chromatin compartment A/B, topological associated domain (TAD), and chromatin loop. These hierarchical structural units play vital roles in gene transcription and regulation. In this review, we summarize the 3D hierarchical division of chromosomes, the effects of hierarchical units and the applications of Hi-C technology in development and disease. This review is intended to provide insights for the further study of 3D genomics in mammals.
