Assesment of gene expression upon AF10 deletion in MLL-AF9 secondary leukemia

Aberrant Hox gene activation is a recurrent feature in several different types of human leukemia, including leukemias with rearrangements of the mixed lineage leukemia (MLL) gene. In this study, we demonstrate that Hox gene expression is controlled by higher degree H3K79 methylation in acute myeloid leukemia (AML). We show that the deposition of progressive H3K79 methylation states at the genomic loci of critical Hox genes is dependent on the interaction of the H3K79 methyltransferase Dot1l with Af10, a protein that is found in the Dot1l complex isolated from diverse cell types. Furthermore, abrogation of the Dot1l-Af10 interaction reverses aberrant epigenetic profiles found in the leukemia epigenome and impairs the transforming ability of mechanistically distinct AML oncogenes. Primary MLL-AF9 leukemias in the AF10 floxed background (homozygous) were transduced with MSCV-IRES-tdTomato (MIT) or the Cre recombinase expressing MIT vector, cells were sorted and injected into secondary recipient mice to generate Af10 floxed (MIT) or deleted (CRE) leukemias. BM cells fresly harvested from these leukemias were sorted for tdTomato expression and used for microarrays. BM cells from Hoxa9-Meis1 transduced primary leukemias were used for comparison.