Regulation of Genome Architecture and Function by Polycomb Proteins

Abstract

Polycomb group (PcG) proteins dynamically define cellular identities through the epigenetic repression of key developmental regulatory genes. PcG proteins are recruited to specific regulatory elements to modify the chromatin surrounding them. In addition, they regulate the organization of their target genes in the 3D space of the nucleus, and this regulatory function of the 3D genome architecture is involved in cell differentiation and the maintenance of cellular memory. In this review we discuss recent advances in our understanding of how PcG proteins are recruited to chromatin to induce local and global changes in chromosome conformation and regulate their target genes. Nuclear architecture is not only important for the efficient compaction and decompaction of the genome during cell division, but has important functions in coordinating gene regulatory networks and orchestrating cellular identity.Changes in nuclear organization are considered an important complement to epigenetic mechanisms contributing to robust and stable gene silencing.Recruitment of Polycomb group (PcG) proteins to their target sites not only modulates local chromatin structure but also mediates looping interactions between regulatory elements and shapes global nuclear architecture, thereby regulating gene expression at multiple scales.The evolutionarily conserved PcG proteins regulate cell identity and cell differentiation by orchestrating 3D genome architecture.