Abstract
Mammalian adult hematopoietic stem cells (HSCs) reside in the hypoxic bone marrow microenvironment and display a distinct metabolic phenotype compared with their progenitors. It has been proposed that HSCs generate energy mainly through anaerobic glycolysis in a pyruvate dehydrogenase kinase (Pdk)-dependent manner. Cited2 is an essential regulator for HSC quiescence, apoptosis, and function. Herein, we show that conditional deletion of Cited2 in murine HSCs results in elevated levels of reactive oxygen species, decreased cellular glutathione content, increased mitochondrial activity, and decreased glycolysis. At the molecular level, Cited2 deficiency significantly reduced the expression of genes involved in metabolism, such as Pdk2, Pdk4, and lactate dehydrogenases B and D (LDHB and LDHD). Cited2-deficient HSCs also exhibited increased Akt signaling, concomitant with elevated mTORC1 activity and phosphorylation of FoxOs. Further, inhibition of PI3/Akt, but not mTORC1, partially rescued the repression of Pdk4 caused by deletion of Cited2. Altogether, our results suggest that Cited2 is required for the maintenance of adult HSC glycolytic metabolism likely through regulating Pdk2, Pdk4, LDHB, LDHD, and Akt activity.