Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA.
Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA; Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, MA 02142, USA.
Mol Cell. 2018 Mar 15;69(6):1039-1045.e3. doi: 10.1016/j.molcel.2018.02.007. Epub 2018 Mar 8.
Imaging (fluorescence in situ hybridization [FISH]) and genome-wide chromosome conformation capture (Hi-C) are two major approaches to the study of higher-order genome organization in the nucleus. Intra-chromosomal and inter-chromosomal interactions (referred to as non-homologous chromosomal contacts [NHCCs]) have been observed by several FISH-based studies, but locus-specific NHCCs have not been detected by Hi-C. Due to crosslinking, neither of these approaches assesses spatiotemporal properties. Toward resolving the discrepancies between imaging and Hi-C, we sought to understand the spatiotemporal properties of NHCCs in living cells by CRISPR/Cas9 live-cell imaging (CLING). In mammalian cells, we find that NHCCs are stable and occur as frequently as intra-chromosomal interactions, but NHCCs occur at farther spatial distance that could explain their lack of detection in Hi-C. By revealing the spatiotemporal properties in living cells, our study provides fundamental insights into the biology of NHCCs.
成像（荧光原位杂交[FISH]）和全基因组染色体构象捕获（Hi-C）是研究细胞核中高级基因组组织的两种主要方法。几项基于 FISH 的研究已经观察到了染色体内和染色体间的相互作用（称为非同源染色体接触[NHCCs]），但 Hi-C 并未检测到局域 NHCCs。由于交联，这两种方法都不能评估时空特性。为了解决成像和 Hi-C 之间的差异，我们试图通过 CRISPR/Cas9 活细胞成像（CLING）来了解活细胞中 NHCCs 的时空特性。在哺乳动物细胞中，我们发现 NHCCs 是稳定的，并且与染色体内相互作用一样频繁，但 NHCCs 发生在更远的空间距离，这可以解释它们在 Hi-C 中未被检测到。通过揭示活细胞中的时空特性，我们的研究为 NHCCs 的生物学提供了基本的见解。
