%0 Journal Article %A Davide Colì %A Davide Michieletto %A Davide Marenduzzo %A Enzo Orlandini %T Magnetic Polymer Models for Epigenomic Organisation and Phase Separation %D 2018 %R 10.1101/379941 %J bioRxiv %P 379941 %X The genetic instructions stored in the genome require an additional layer of information to robustly determine cell fate. This additional regulation is provided by the interplay between chromosome-patterning biochemical (“epigenetic”) marks and threedimensional genome folding. Yet, the physical principles underlying the dynamical coupling between three-dimensional genomic organisation and one-dimensional epigenetic patterns remain elusive. To shed light on this issue, here we study by mean field theory and Brownian dynamics simulations a magnetic polymer model for chromosomes, where each monomer carries a dynamic epigenetic mark. At the single chromosome level, we show that a first order transition describes the unlimited spreading of epigenetic marks, a phenomenon that is often observed in vivo. At the level of the whole nucleus, experiments suggest chromosomes form micro-phase separated compartments with distinct epigenetic marks. We here discover that for a melt of magnetic polymers such a morphology is thermodynamically unstable, but can be stabilised by a nonequilibrium and ATP-mediated epigenetic switch between different monomer states. %U https://www.biorxiv.org/content/biorxiv/early/2018/07/30/379941.full.pdf