Epigenetic balance of gene expression by Polycomb and COMPASS families

A balancing act in modifying chromatin Chromatin modifiers add chemical groups to histones, the proteins that package DNA. These modifications are central to cellular development, and mutations in their molecular machinery are linked to a variety of human diseases. Piunti and Shilatifard review the balance between the prototypic chromatin modifiers Polycomb and COMPASS complexes and their role in gene regulation and normal development. Although originally identified as indispensible regulators of fruit fly development, related roles have been identified in other organisms. Furthermore, mutations in human homologs have been implicated in various cancers. As such, these complexes may serve as effective targets for epigenetic therapies. Science , this issue p. 10.1126/science.aad9780