Cytosine hypermethylation in and around DNA binding sites of master transcription factors, including PU.1, occurs in aging hematopoietic stem cells following acquired loss-of-function mutations of DNA methyl-cytosine dioxygenase Ten-Eleven Translocation-2 (TET2), albeit functional relevance has been unclear. We show that Tet2 deficient mouse hematopoietic stem and progenitor cells undergo malignant transformation upon compromised gene regulation through heterozygous deletion of an upstream regulatory region (UREd/WT) of the PU.1 gene. While compatible with multilineage blood formation at young age, Tet2 deficient PU.1 UREd/WT mice develop highly penetrant, transplantable acute myeloid leukemia (AML) during aging. Leukemic stem and progenitor cells show hypermethylation at putative PU.1 binding sites, fail to activate myeloid enhancers, and are hallmarked by a signature of genes with impaired expression shared with human AML. Our study demonstrates that Tet2 and PU.1 jointly suppress leukemogenesis and uncovered a methylation sensitive PU.1-dependent gene network as a unifying molecular vulnerability associated with AML.
