Theoretical analysis of Polycomb-Trithorax systems predicts that poised chromatin is bistable and not bivalent.

ABSTRACT: Polycomb (PcG) and Trithorax (TrxG) group proteins give stable epigenetic memory of silent and active gene expression states, but also allow poised states in pluripotent cells. Here we systematically address the relationship between poised, active and silent chromatin, by integrating 73 publications on PcG/TrxG biochemistry into a mathematical model comprising 144 nucleosome modification states and 8 enzymatic reactions. Our model predicts that poised chromatin is bistable and not bivalent. Bivalent chromatin, containing opposing active and silent modifications, is present as an unstable background population in all system states, and different subtypes co-occur with active and silent chromatin. In contrast, bistability, in which the system switches frequently between stable active and sil

SUBMITTER: Sneppen K 

PROVIDER: S-EPMC6513952 | biostudies-literature | 2019 May

REPOSITORIES: biostudies-literature