Histone H3 lysine 4 trimethylation (H3K4me3)

Histone H3 lysine 4 trimethylation (H3K4me3) is a critical epigenetic modification typically localized at the transcription start sites of actively transcribed genes. It acts as a transcriptional scaffold, recruiting 'reader' proteins such as TFIID and various chromatin remodelers to facilitate the assembly of the pre-initiation complex and RNA polymerase II. The modification is dynamically regulated by the SET1/MLL (KMT2) family of methyltransferases, often referred to as 'writers,' and removed by the KDM5 family of demethylases, known as 'erasers.' In many cancers, particularly MLL-rearranged leukemias, the regulation of H3K4me3 is subverted, leading to the sustained expression of oncogenic programs and blocking cellular differentiation. Therapeutic intervention focuses on small molecules that disrupt the MLL complex assembly (e.g., Menin-MLL inhibitors) or inhibit demethylase activity to correct these aberrant epigenetic landscapes. Beyond oncology, H3K4me3 is vital for proper embryonic development and its disruption is linked to various neurodevelopmental and intellectual disability syndromes.

Other names

H3K4me3Trimethyl-histone H3 (Lys4)H3 Lys4 trimethylationH3K4 trimethyl

Modulation of H3K4me3 levels through the inhibition of 'writer' complexes (e.g., Menin-MLL interaction) to decrease oncogenic transcription, or 'eraser' enzymes (e.g., KDM5 demethylases) to restore tumor suppressor activity.