GSE202696
Distinct and opposite effects of leukemogenic Idh and Tet2 mutations in hematopoietic stem and progenitor cells
Mutations in IDH1, IDH2, and TET2 are recurrently observed in myeloid neoplasms and may influence prognosis. IDH1 and IDH2 encode isocitrate dehydrogenase isoforms, which normally catalyze the conversion of isocitrate to a-ketoglutarate (a-KG).  Oncogenic IDH1/2 mutations confer neomorphic activity, leading to the production of D-2-hydroxyglutarate (D-2-HG), a potent inhibitor of a-KG-dependent enzymes which include TET methylcytosine dioxygenases. Given their mutual exclusivity in myeloid neoplasms, IDH1, IDH2, and TET2 mutations are thought to converge on a common oncogenic mechanism. Contrary to this expectation, we observed that they have non-overlapping, and even opposite, effects on hematopoietic stem and progenitor cells in genetically engineered mice. Epigenetic and single-cell transcriptomic analyses revealed that Idh2R172K and Tet2 loss-of-function have divergent consequences on the expression and activity of key hematopoietic and leukemogenic regulators. Notably, chromatin accessibility and transcriptional dysregulation in Idh2R172K cells were partially disconnected from DNA methylation alterations. These results highlight unanticipated divergent effects of IDH1/2 and TET2 mutations, providing support for the optimization of genotype-specific therapies in myeloid neoplasms. Overall design: Lin-cKit+Sca1+ cells from 3-4 month old +/+; Vav-Cre (control), Idh1LSL-R132H/+;Vav-Cre, Idh2LSL-R140Q/+;Vav-Cre, and Idh2LSL-R172K/+;Vav-Cre mice were analyzed. For each genotype,  4 pools of 2 mice each (each forming a biological replicate), were analyzed.