The cell type specific 5hmC landscape and dynamics of healthy human hematopoiesis and TET2-mutant pre-leukemia
Nakauchi Y., Azizi A., Thomas D., Corces MR., Reinisch A., Sharma R., Cruz Hernandez D., Kohnke T., Karigane D., Fan A., Martinez-Krams D., Stafford M., Kaur S., Dutta R., Phan P., Ediriwickrema A., McCarthy E., Ning Y., Phillips T., Ellison CK., Guler GD., Bergamaschi A., Ku C-J., Levy S., Majeti R.
Abstract The conversion of 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC) is a key step in DNA demethylation that is mediated by ten-eleven-translocation (TET) enzymes, which require ascorbate/vitamin C. Here, we report the 5hmC landscape of normal hematopoiesis and identify cell type-specific 5hmC profiles associated with active transcription and chromatin accessibility of key hematopoietic regulators. We utilized CRISPR/Cas9 to model TET2 loss-of-function mutations in primary human HSPCs. Disrupted cells exhibited increased colonies in serial replating, defective erythroid/megakaryocytic differentiation, and in vivo competitive advantage and myeloid skewing coupled with reduction of 5hmC at erythroid-associated gene loci. Azacitidine and ascorbate restored 5hmC abundance and slowed or reverted the expansion of TET2-mutant clones in vivo. These results demonstrate the key role of 5hmC in normal hematopoiesis and TET2-mutant phenotypes and raise the possibility of utilizing these agents to further our understanding of pre-leukemia/clonal hematopoiesis.