RNA-seq analysis in RISP WT and KO hematopoietic stem cells. Mus musculus

Adult and fetal hematopoietic stem cells (HSCs) display a glycolytic phenotype required to maintain stem cell properties; however, whether mitochondrial respiration is required to maintain HSC function is not known. Here we report that loss of the mitochondrial complex III subunit Rieske iron sulfur protein (RISP), encoded by the Uqcrfs1 gene, in fetal mouse HSCs, results in anemia and prenatal death. RISP null fetal HSCs displayed impaired respiration, resulting in a decreased NAD+/NADH ratio and an increase in glycolysis. While they were viable and able to robustly proliferate in vivo, RISP null fetal HSCs had impaired differentiation, resulting in a depletion of the progenitor pool. RNA-seq analysis revealed widespread changes in gene expression due to loss of RISP in fetal HSCs. Furthermore, RISP null fetal HSCs and progenitors exhibited an increase in both DNA and histone methylation concomitant with increases in 2-hydroxyglutarate (2-HG), a metabolite known to inhibit DNA and histone demethylases. RISP inactivation in adult HSCs also impaired respiration, resulting in a decreased NAD+/NADH ratio, increased glycolysis and loss of quiescence, followed by rapid depletion resulting in severe pancytopenia and lethality. The effect of RISP ablation in fetal or adult HSCs was cell-autonomous. Together, these data indicate that respiration is dispensable for HSC proliferation, but essential for HSC differentiation and maintenance of adult HSC quiescence. Overall design: RNA-seq was performed to determine gene expression changes in RISP (Uqcrfs1) WT and KO fetal liver HSCs