GSE192988
Bulk and single cell profiling of CD45+ LSK cells collected from WT and TET2 deficient mice under normoxia and hypoxia (physioxia) conditions (BULK RNA-SEQ)
Hematopoietic stem cells (HSCs) manifest impaired recovery and self-renewal with a concomitant increase in progenitor content (HPCs) when exposed to ambient air as opposed to physioxia. Mechanisms behind this distinction are poorly understood but have the potential to enhance HSC function for bone marrow transplantation. High resolution transcriptomic analysis revealed that HSCs under physioxia (HSCs- P) upregulate genes involved in self-renewal and quiescence but downregulate genes involved in apoptosis and differentiation compared to HSCs-A. Remarkably, among several genes, Tet2 was significantly downregulated in HSC-Ps compared to HSC-As, which was associated with reduced 5-hydroxymethylcytosine (5-hmC) levels in HSC-Ps. Interestingly, individuals carrying the TET2 mutation in their HSCs are at a higher risk of developing clonal hematopoiesis, myeloid leukemias and cardiovascular disease. Loss of Tet2 in mice results in more HSCs and enhanced self-renewal. TET enzymes are a-ketoglutarate, iron and oxygen-dependent dioxygenases that convert 5-methylcytosine to 5-hydroxymethylcytosine thereby promoting active transcription. We evaluated whether physioxia affects the numbers and function of HSCs and HPCs from Tet2-/- mice similar to wildtype (WT) mice. In contrast to WT-HSCs, we observed complete non-responsiveness of Tet2-/- HSCs to changes in oxygen tension. Tet2-/- HSCs and HPCs exhibited similar numbers and function under physioxia and ambient air. The lack of functional responsiveness to changes in oxygen tension in Tet2-/- HSCs was associated with similar changes in genes involved in self-renewal and quiescence among WT-HSC-Ps, Tet2-/- HSC-Ps and Tet2-/- HSC-As. Our findings define a novel molecular program involving Tet2 in regulating the self-renewal of HSCs under physioxia. Overall design: CD45+ cells were extracted under four conditions namely WT and TET2 knockout under normoxia and physioxia conditions