DOT1L Inhibits SIRT1 and SUV39H1-Mediated H3K9 Modification to Maintain Gene Expression (array). Mus musculus

Methylation of histone 3 on lysine 79 (H3K79) is broadly associated with active gene expression in eukaryotes, and the H3K79 methyltransferase DOT1L is indispensable for specific leukemia subtypes like those with MLL-translocations. We found that suppression of the histone deacetylase SIRT1 rescued MLL-AF9 leukemia cells from their dependence on DOT1L. We show that upon DOT1L inhibition, SIRT1 is required for the acquisition of a repressive chromatin state consistent with facultative heterochromatin around MLL-AF9 target genes in leukemia and other genes possess an H3K79me2(hi), H3K9ac(hi), H3K9me2(low) histone modification profile in normal hematopoietic stem and progenitor cells. Overall design: Examination of gene expression dynamics with and without drug treatment and RNA interference.