Tip60 activates Hoxa9 and Meis1 expression through acetylation of H2A.Z, promoting MLL-AF10 and MLL-ENL acute myeloid leukemia

Chromosome translocations involving the MLL gene are common rearrangements in leukemia. Such translocations fuse the MLL 5'-region to partner genes in frame, producing MLL-fusions that cause MLL-related leukemia. MLL-fusions activate transcription of target genes such as HoxA cluster and Meis1, but the underlying mechanisms remain to be fully elucidated. In this study, we discovered that Tip60, a MYST-type histone acetyltransferase, was required for the expression of HoxA cluster and Meis1 genes and the development of MLL-fusion leukemia. Tip60 was recruited by MLL-AF10 and MLL-ENL fusions to the Hoxa9 locus, where it acetylated H2A.Z, thereby promoting Hoxa9 gene expression. Conditional deletion of Tip60 prevented the development of MLL-AF10 and MLL-ENL leukemia, indicating that Tip60 is indispensable for the leukemogenic activity of the MLL-AF10 and MLL-ENL-fusions. Our findings provide novel insight about epigenetic regulation in the development of MLL-AF10 and MLL-ENL-fusion leukemia.