ASH1 like histone lysine methyltransferase (ASH1L)

ASH1 like histone lysine methyltransferase (ASH1L) is a large, multi-domain enzyme that catalyzes the mono- and dimethylation of histone H3 at lysine 36 (H3K36me1/2), a key chromatin modification linked to active gene transcription. ASH1L is encoded by the ASH1L (KMT2H) gene located on chromosome 1q22 and is homologous to the Drosophila Trithorax-group protein Ash1, which is critical for Hox gene regulation and maintenance of cell identity. ASH1L is widely expressed in mammalian tissues, with a crucial role in brain development, stem cell differentiation, and hematopoiesis. Mutations or dysregulation of ASH1L have been implicated in various human diseases, most notably MLL-rearranged leukemia and neurodevelopmental disorders such as autism and epilepsy. The enzyme contains a central catalytic SET domain, as well as multiple chromatin reader domains (bromodomain, PHD finger, and BAH domain), which enable it to recognize both histone and DNA marks and help orchestrate transcriptional activation programs. Recent studies have developed selective small-molecule inhibitors targeting the autoinhibitory loop of the SET domain, validating ASH1L as a potentially druggable target for certain leukemias. However, the enzyme's broad expression and central epigenetic roles raise concerns for possible side effects when targeted therapeutically.

Other names

ASH1ASH1L1KMT2HKIAA1420huASH1lysine N-methyltransferase 2Habsent small and homeotic disks protein 1 homologprobable histone-lysine N-methyltransferase ASH1L

Inhibition of the SET domain's methyltransferase activity, particularly reducing mono- and dimethylation of histone H3 lysine 36 (H3K36), blocking gene activation and resulting in antiproliferative, pro-apoptotic, and differentiating effects in target cells