Related Experiment Video
Updated: Jan 5, 2026
A Method to Study de novo Formation of Chromatin Domains
Published on: August 23, 2019
PRC2 engages a bivalent H3K27M-H3K27me3 dinucleosome inhibitor
Katharine L Diehl1, Eva J Ge1, Daniel N Weinberg2
1Department of Chemistry, Princeton University, Princeton, NJ 08544.
Abstract:
A lysine-to-methionine mutation at lysine 27 of histone 3 (H3K27M) has been shown to promote oncogenesis in a subset of pediatric gliomas. While there is evidence that this "oncohistone" mutation acts by inhibiting the histone methyltransferase PRC2, the details of this proposed mechanism nevertheless continue to be debated. Recent evidence suggests that PRC2 must simultaneously bind both H3K27M and H3K27me3 to experience competitive inhibition of its methyltransferase activity. In this work, we used PRC2 inhibitor treatments in a transgenic H3K27M cell line to validate this dependence in a cellular context. We further used designer chromatin inhibitors to probe the geometric constraints of PRC2 engagement of H3K27M and H3K27me3 in a biochemical setting. We found that PRC2 binds to a bivalent inhibitor unit consisting of an H3K27M and an H3K27me3 nucleosome and exhibits a distance dependence in its affinity for such an inhibitor, which favors closer proximity of the 2 nucleosomes within a chromatin array. Together, our data precisely delineate fundamental aspects of the H3K27M inhibitor and support a model wherein PRC2 becomes trapped at H3K27M-H3K27me3 boundaries.
Insights
The H3K27M oncohistone mutation in pediatric gliomas inhibits PRC2 by binding to both H3K27M and H3K27me3 nucleosomes. This binding is distance-dependent, trapping PRC2 at H3K27M-H3K27me3 boundaries.
Area of Science:
- Epigenetics
- Cancer Biology
- Molecular Biology
Background:
- The H3K27M mutation in histone 3 promotes pediatric glioma development.
- This mutation is proposed to inhibit the PRC2 enzyme, a key regulator of chromatin methylation.
- The precise mechanism of PRC2 inhibition by H3K27M remains under investigation.
Purpose of the Study:
- To validate the dependence of PRC2 inhibition on simultaneous binding to H3K27M and H3K27me3 in a cellular context.
- To investigate the geometric constraints of PRC2 engagement with H3K27M and H3K27me3 using designer chromatin inhibitors.
- To elucidate the fundamental aspects of H3K27M-mediated PRC2 inhibition.
Main Methods:
- Utilized PRC2 inhibitor treatments in a transgenic H3K27M cell line.
- Employed designer chromatin inhibitors to probe biochemical interactions.
- Analyzed the geometric constraints and distance dependence of PRC2 binding.
Main Results:
- Confirmed that PRC2 inhibition requires simultaneous binding to both H3K27M and H3K27me3 nucleosomes in cells.
- Biochemical experiments revealed that PRC2 binds a bivalent inhibitor unit comprising H3K27M and H3K27me3 nucleosomes.
- Demonstrated a distance-dependent affinity of PRC2 for this bivalent inhibitor, favoring closer nucleosome proximity.
Conclusions:
- Provided precise delineation of the H3K27M inhibitor mechanism.
- Supported a model where PRC2 becomes trapped at the boundaries between H3K27M and H3K27me3 nucleosomes.
- Offered insights into the structural requirements for PRC2 inhibition by oncohistones.
Related Concept Videos
02:38Heterochromatin
Constitutive heterochromatin: It is a highly compact region of chromatin that is mostly concentrated in the centromere and telomere. Unlike euchromatin, the amino acid at...
02:25Spreading of Chromatin Modifications
Writers
The writer...
02:36Chromatin Immunoprecipitation- ChIP
Types of ChIP
ChIP can be divided into two types - X-ChIP and N-ChIP. X-ChIP involves in vivo cross-linking of histones and regulatory proteins to DNA, fragmenting the DNA by sonication, and isolating the protein-DNA...
01:01Euchromatin
Euchromatin is the less dense region of the chromatin and stains lighter. Euchromatin contains histone H3 extensively...
03:17Inheritance of Chromatin Structures
02:13Cooperative Binding of Transcription Regulators