PRC2.1 and PRC2.2 synergize to co-ordinate H3K27 tri-methylation.

Polycomb Repressive Complex 2 (PRC2) is composed of EED, SUZ12, and EZH1/2 and mediates mono-, di- and tri-methylation of Histone H3 at Lysine 27. While at least two subcomplexes exist, defined by their specific accessory proteins, termed PRC2.1 (Polycomb-like proteins 1-3, EPOP and PALI1/2) and PRC2.2 (AEBP2 and JARID2), little is known about their differential functions. Here, we show that PRC2.1 and PRC2.2 share the majority of target genes in mouse embryonic stem cells (ESCs). The loss of all three Polycomb-like proteins is sufficient to destabilise and evict PRC2.1 from chromatin, but also leads to reduced PRC2.2 and H3K27me3 at most Polycomb domains. However, the combined loss of PRC2.1 and PRC2.2 is necessary to completely remove H3K27me3 at broad Polycomb domains such as the Hox loci. Our data support a model in which the specific accessory proteins within PRC2.1 and PRC2.2 co-operate to direct and maintain H3K27me3, via both synergistic and independent mechanisms. Quantitative ChIP-Rx analysis of Pcl1-3 WT EV, Pcl1-3 TKO EV and Pcl1-3/Jarid2 c12 QKO mouse embryonic stem cells. ChIPs include a 10% spike in of human chromatin (NT2 cell line). 25 samples are included.