Inhibition of PRC2 Activity by a Gain-of-Function H3 Mutation Found in Pediatric Glioblastoma
Menée sur des échantillons tumoraux prélevés sur des patients pédiatriques atteints d'un gliome intrinsèque diffus du pont, cette étude met en évidence un mécanisme par lequel une mutation du gène de l'histone H3 inhibe l'activité enzymatique du complexe PRC2
Sequencing of pediatric gliomas has identified missense mutations Lys27Met (K27M) and Gly34Arg/Val (G34R/V) in genes encoding histone H3.3 (H3F3A) and H3.1 (HIST3H1B). We report that human diffuse intrinsic pontine gliomas (DIPGs) containing the K27M mutation display significantly lower overall H3K27me3 levels, and that histone H3K27M transgenes are sufficient to reduce H3K27me3 levels in vitro and in vivo. We find that H3K27M inhibits the enzymatic activity of the Polycomb repressive complex 2 (PRC2) through interaction with the EZH2 subunit. Additionally, transgenes containing lysine-to-methionine substitutions at other known methylated lysines (H3K9 and H3K36) are sufficient to cause specific reduction in methylation levels through inhibition of SET-domain enzymes. We propose that K-to-M substitutions may represent a mechanism to alter epigenetic states in a variety of pathologies.