Abstract

Somatic mutations in protein lysine methyltransferases are frequently observed in cancer cells. We show here that the NSD1 mutations Y1971C, R2017Q and R2017L observed mostly in solid cancers are catalytically inactive suggesting that NSD1 acts as tumor suppressor gene in these tumors. In contrast, the frequent T1150A in NSD2 and its T2029A counterpart in NSD1, both observed in leukemia, are hyperactive and introduce up to H3K36me3 in biochemical and cellular assays, while wildtype NSD2 and NSD1 only generate up to H3K36me2. MD simulations with NSD2 revealed that H3K36me3 formation is possible due to an enlarged active site pocket of T1150A and loss of direct contacts of T1150 to critical residues which regulate the product specificity of NSD2. Bioinformatic analyses of published data suggest that the NSD2 T1150A mutation in lymphocytic leukemia could alter gene regulation by antagonizing H3K27me3 finally leading to the upregulation of oncogenes.