Two Functional Axes of Feedback-Enforced PRC2 Recruitment in Mouse Embryonic StemCells.

Matteo Perino,Sandra M.T Wardle,Hendrik Marks,Guido Van Mierlo,Chet Loh,Dick W Zijlmans,Gert Jan C Veenstra

doi:10.1016/j.stemcr.2020.07.007

Abstract

SummaryPolycomb Repressive Complex 2 (PRC2) plays an essential role in gene repression during development, catalyzing 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.

Highlights

Cell fate specification during embryonic development requires tightly controlled epigenetic programs
Polycomb Repressive Complex 2 (PRC2) Recruitment Mainly Depends on MTF2 Recent advances have pinpointed three main recruitment mechanisms of PRC2: (1) DNA-mediated recruitment via MTF2; (2) recruitment via JARID2; and (3) H3K27me3mediated recruitment via EED (Figure 1A) (Cooper et al, 2016; Li et al, 2017; Margueron et al, 2009; Oksuz et al, 2018; Pasini et al, 2010; Perino et al, 2018)
To investigate how they contribute to establishing PRC2 binding at target genes, we first evaluated whether these mechanisms act at the same genomic sites by performing chromatin immunoprecipitation followed by massive parallel sequencing (ChIP-seq) using antibodies against endogenous EZH2, H3K27me3, MTF2, and JARID2

Summary

Introduction

Cell fate specification during embryonic development requires tightly controlled epigenetic programs. The critical role of PRC2 during developmental processes is underscored by the embryonic lethality observed in mice lacking a functional PRC2 complex (Faust et al, 1998; O’Carroll et al, 2001; Pasini et al, 2007). PRC2 contains multiple ancillary subunits exerting functions, such as guiding PRC2 to target genes and modulating its enzymatic activity. These include Polycomb-like proteins (PHF1, MTF2, or PHF19, known as PCL1-3), EPOP ( known as C17ORF96), and PALI1/2 ( known as C10ORF12), which, together with the core subunits, form PRC2.1. The PRC2 core can associate with JARID2 and AEBP2 in another PRC2 sub-complex, referred to as PRC2.2 (Conway et al, 2018; van Mierlo et al, 2019a)

Results

Discussion

Conclusion