Grasping trimethylation of histone H3 at lysine 4

Post-translational modifications of chromatin have become a 'booming' area of biomedical research. One particularly interesting modification that is important for eukaryotic gene expression is trimethylation of histone H3 lysine 4 (H3K4me3), which is almost exclusively associated with active promoters of RNA polymerase II. In this article, we highlight the recent progress related to the biochemistry and biology of this histone mark, including its relevant 'writers' and 'readers'. We also outline the complex regulatory mechanisms that are involved in establishing H3K4me3 in health and disease. Further understanding of H3K4me3 regulation will offer both more insight into chromatin-based mechanisms of gene regulation and provide opportunities for epigenetic intervention of the diseased state.