GSE158447
Dual interactions of K27M mutant nucleosomes with PRC2 and MLL1 shape the cancer epigenetic landscape (Cut&Run)
Cancer associated mutations in genes encoding histones dramatically reshape chromatin patterns and support tumorigenesis, despite their low prevalence. Lysine to Methionine substitution of residue 27 on histone H3 (K27M) is a driver mutation in high-grade pediatric gliomas, known to abrogate Polycomb activity. We applied single-molecule systems to image individual nucleosomes and delineate the combinatorial chromatin patterns associated with K27M expression. We find that K27M-mutant nucleosomes not only sequester PRC2, but also bind preferentially to MLL1, thus leading to genome-wide redistribution of H3K4me3. K27M-mediated deregulation of both repressive and activating chromatin marks maintains 'bivalent' chromatin, supporting a poorly differentiated cellular state. This study provides evidence for widespread effects of the K27M oncohistone on multiple core epigenetic pathways, and highlights the use of single-molecule tools to reveal mechanisms of chromatin deregulation in cacner. Overall design: Cut&Run analysis of patient-derived DIPG cells. Performed on SU-DIPG using primary antibodies: anti-histone H3K27M, anti-histone H3K27ac, anti-histone H3K27me3, anti-histone H3K4me3, anti-MLL1 and anti-EZH2. Secondary antibody anti-rabbit HRP was used as a negative control.