Polycomb Proteins Remain Bound to Chromatin and DNA during DNA Replication In Vitro

Abstract

Summary The transcriptional status of a gene can be maintained through multiple rounds of cell division during development. This epigenetic effect is believed to reflect heritable changes in chromatin folding and histone modifications or variants at target genes, but little is known about how these chromatin features are inherited through cell division. A particular challenge for maintaining transcription states is DNA replication, which disrupts or dilutes chromatin associated proteins and histone modifications. PRC1-class Polycomb Group protein complexes are essential for development, and are thought to heritably silence transcription by altering chromatin folding and histone modifications. It is not known whether these complexes and their effects are maintained during DNA replication or subsequently re-established. We find that when PRC1-class Polycomb complex-bound chromatin or DNA is replicated in vitro, Polycomb complexes remain bound to replicated templates. Retention of Polycomb proteins through DNA replication may contribute to maintenance of transcriptional silencing through cell division.

Epigenetic regulation of vertebrateHoxgenes: A dynamic equilibrium

“…8 Biochemical studies have revealed that PcG and TrxG form multi-protein complexes, containing both histone methyltransferase activity as well as proteins binding methylated histone lysine residues. 6,9,10 The components of the Polycomb Repressive Complex 2 (PRC2) tri-methylate H3K27(me3) [11][12][13][14] and bind to the same histone mark 15,16 that is essential for inheritable long-term repression of target genes. Recruitment of PRC1 members to H3K27me3 further facilitates gene silencing via ubiquitination of H2A at K119, [17][18][19] a modification that interferes with RNA Polymerase II activity.…”

PRC1 Prevents Replication Stress during Chondrogenic Transit Amplification

“…Of note, this occurs in midS-phase, a period during which we and others have observed dynamic regulation of PRC1-chromatin association involving PRC1 phosphorylation [73]. As PRC complexes were shown to remain associated with chromatin during DNA replication [36,69,74], this ideally positions PRC1 to locally tune transcription to replication activity. Of relevance, PRC1-proteins were shown to occupy promoters of actively transcribed genes and are required for POLR2A complex disassembly [41,75].…”

Ctf4-related protein recruits LHP1-PRC2 to maintain H3K27me3 levels in dividing cells in Arabidopsis thaliana

“…6). Furthermore, in animals it has been speculated that association of PRC2 with the replication fork may be promoted by affinity of the E(z) component to single-stranded DNA that is generated upon unwinding by the helicase complex (46,47).…”