Automethylation of PRC2 promotes H3K27 methylation and is impaired in H3K27M pediatric glioma

Abstract

The histone methyltransferase activity of PRC2 is central to the formation of H3K27me3-decorated facultative heterochromatin and gene silencing. In addition, PRC2 has been shown to automethylate its core subunits, EZH1/ EZH2 and SUZ12. Here, we identify the lysine residues at which EZH1/EZH2 are automethylated with EZH2-K510 and EZH2-K514 being the major such sites in vivo. Automethylated EZH2/PRC2 exhibits a higher level of histone methyltransferase activity and is required for attaining proper cellular levels of H3K27me3. While occurring independently of PRC2 recruitment to chromatin, automethylation promotes PRC2 accessibility to the histone H3 tail. Intriguingly, EZH2 automethylation is significantly reduced in diffuse intrinsic pontine glioma (DIPG) cells that carry a lysine-to-methionine substitution in histone H3 (H3K27M), but not in cells that carry either EZH2 or EED mutants that abrogate PRC2 allosteric activation, indicating that H3K27M impairs the intrinsic activity of PRC2. Our study demonstrates a PRC2 self-regulatory mechanism through its EZH1/2-mediated automethylation activity.

Invited Review: Emerging functions of histone H3 mutations in paediatric diffuse high‐grade gliomas

“…Additionally, work by Lee et al . has shown that H3K27M reduces the level of EZH2 automethylation, which decreases PRC2 methyltransferase activity in a manner that most dramatically affects the conversion of H3K27me2 to me3 . This is consistent with the relative effects of H3K27M on H3K27me2 vs. H3K27me3 quantity and deposition .…”

“…Recent studies have provided data that help to resolve the apparent contradictions between experimental observations and the PRC2 sequestration model, and instead propose a model in which interaction with H3K27M causes lasting changes to PRC2 that impair its function (Figure A ). Utilizing inducible expression of H3K27M and ChIP‐seq across multiple timepoints, Stafford.…”

JARID2 and AEBP2 regulate PRC2 activity in the presence of H2A ubiquitination or other histone modifications

“…In the present structure we have now been able to identify and model a region of EZH2 rich in lysines and arginines (aa 487-513) that interacts extensively with the nucleosomal DNA. The region includes lysines K509 and K510 within the IQLKK motif of EZH2, which had been predicted to be disordered and shown to be modified during PRC2 auto-methylation (25,26). Mass spectrometry analysis of our PRC2-AJ1-450 sample confirms the presence of dimethylation of both K509 and K510.…”

“…Data and material availability: Cryo-EM density maps and fitted models have been deposited in the Electron Microscopy Data Bank (EMDB) and the PDB for the PRC2-AEBP2-JARID2 (1-450) bound to Ncl-ub (EMDB: 21707 and PDB: 6WKR). [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] with the corresponding atomic model. Clear density for residues R26 and K27, which have been previously observed, as well as density for K23, K36, K37 and V35, allow to define the full extent of interaction between EZH2 (SET) and the histone H3 tail.…”

The histone methyltransferase DOT1L prevents antigen-independent differentiation and safeguards epigenetic identity of CD8+T cells

“…However, the exact mechanisms by which DOT1L affects EZH2/PRC2 activity are still unknown. Although PRC2 targets were derepressed, Ezh2 mRNA expression was only modestly reduced in Dot1L-KO peripheral T cells, suggesting that DOT1L not only affects expression of Ezh2 but might also be involved in other processes that regulate PRC2 activity, such as the stability, structure, recruitment, or localization of the PRC2 complex 59,62,91,92,93,94,95,96,97,98,99,100 . H3K79 methylation is not likely to promote H3K27 methylation directly at the level of nucleosomes because the modifications generally occur in different genic regions and mark different sets of genes (e.g.…”