Genome 3D-architecture: Its plasticity in relation to function.

The genome of higher eukaryotes is non-randomly organized in the interphase nucleus. However, notwithstanding the absence of membrane bound sub-compartments, the nucleus coordinates a number of functions largely by organizing chromatin in a non-random but dynamic manner. The plasticity of chromatin structure and function relies on epigenetic modifications as well as its association with nuclear landmarks such as the nuclear envelope, nuclear lamina, nuclear pore complex and nuclear bodies such as the nucleolus among others. In the absence of membrane-bound compartments, cells and the nucleus, in particular, employ phase-separation, which unmixes phases that constrain biochemical reactions in complex non-membranous sub-compartments such as the nucleolus or even the heterochromatin. This review attempts to provide a glimpse into the microcosm of phase-separated nuclear sub-compartments, that regulate nuclear structure- function relationships.