Histone H3 lysine 27 (post-translational modification site on histone H3) (H3K27)

Histone H3 lysine 27 (H3K27) is a specific lysine residue at position 27 on the N-terminal tail of histone H3 that is a major site of post-translational modifications, including acetylation and mono-, di-, and trimethylation. Trimethylation of H3K27 (H3K27me3) is catalyzed mainly by the Polycomb repressive complex 2 (PRC2), whose SET-domain subunit EZH2 provides histone lysine methyltransferase activity, and this mark recruits Polycomb repressive complex 1 (PRC1) to establish and maintain a compact, transcriptionally repressed chromatin state at target genes, especially key developmental regulators. H3K27me3 is a stable repressive epigenetic mark that is dynamically remodeled during early embryonic development to erase gametic programs and establish a pluripotent embryonic epigenome. In contrast, acetylation of H3K27 (H3K27ac) is enriched at active enhancers and promoters and is associated with transcriptionally permissive chromatin. Altered patterns of H3K27 methylation, through dysregulation of PRC2 components such as EZH2 or H3K27 demethylases, are a common feature in many cancers and are being therapeutically targeted with EZH2 inhibitors that indirectly modulate H3K27 methylation status.

Other names

H3K27meH3K27me1H3K27me2H3K27me3Histone H3 K27Histone H3 Lys27Histone H3 lysine 27 methylationHistone H3 lysine 27 trimethylation (H3K27me3)Histone H3 lysine 27 acetylation (H3K27ac)

Inhibition of EZH2 histone methyltransferase in PRC2, leading to decreased H3K27me3, chromatin de-repression, and reactivation of silenced genes in tumor cells; Indirect epigenetic modulation of Polycomb-mediated gene silencing via reduction of the repressive H3K27me mark