Generation of dynamic three-dimensional genome structure through phase separation of chromatin.

Three-dimensional genome structure and dynamics play critical roles in regulating DNA functions. Flexible chromatin structure and movements suggested that the genome is dynamically phase separated to form A (active) and B (inactive) compartments in interphase nuclei. Here, we examine this hypothesis by developing a polymer model of the whole genome of human cells and assessing the impact of phase separation on genome structure. Upon entry to the G1 phase, the simulated genome expanded according to heterogeneous repulsion among chromatin chains, which moved chromatin heterogeneously, inducing phase separation of chromatin. This repulsion-driven phase separation quantitatively reproduces the experimentally observed chromatin domains, A/B compartments, lamina-associated domains, and nucleolus-associated domains, consistently explaining nuclei of different human cells and predicting their dynamic fluctuations. We propose that phase separation induced by heterogeneous repulsive interactions among chromatin chains largely determines dynamic genome organization.