Two distinct functional axes of positive feedback-enforced PRC2 recruitment in mouse embryonic stem cells

Polycomb Repressive Complex 2 (PRC2) plays an essential role in gene repression during development, catalysing H3 lysine 27 trimethylation (H3K27me3). MTF2 in the PRC2.1 sub-complex, and JARID2 in PRC2.2, are central in core PRC2 recruitment to target genes in mouse embryonic stem cells (mESCs). To investigate how PRC2.1 and PRC2.2 cooperate, we combined Polycomb mutant mESCs with chemical inhibition of binding to H3K27me3. We find that PRC2.1 and PRC2.2 mediate two distinct paths for recruitment, which are mutually reinforced. Whereas PRC2.1 recruitment is mediated by MTF2 binding to DNA, JARID2-containing PRC2.2 recruitment is more dependent on PRC1. Both recruitment axes are supported by core subunit EED binding to H3K27me3, but EED inhibition exhibits a more pronounced effect in Jarid2 null cells. Finally, we show that PRC1 and PRC2 enhance reciprocal binding. Together, these data disentangle the interdependent interactions that are important for PRC2 recruitment. ChIP-seq for Mtf2, Ezh2, Jarid2, Ring1b, H3K27me3 and input for reference performed in WT mESC or mESC mutant for Mtf2, Jarid2, EED, Ring1a/b with or without the PRC2 inhibitor EED226 or the PRC1 inhibitor MG32. Validation of quantification with spike-In ChIP for Ezh2 in WT, EED KO and Mtf2 GT lines. Part of the data are re-analized from Perino et al, 2018, Nat. Gen.