Abstract
Peripheral lymphocytes homeostasis is controlled by cytokine signals of which interleukin-7 (IL-7) figures most prominently. Cells deprived of IL-7 exhibit low levels of Adenosine tri-phosphate (ATP). However, little is known of the mechanism by which IL-7 regulates metabolic activity in dependent cells. We reported that shortly after IL-7 withdrawal, T-lymphocytes decreased their glucose uptake. Here we show that T-cells deprived of IL-7 decreased the gene expression and protein levels of the glycolytic enzyme, Hexokinase II (HXKII), required for generating glucose-6-phosphate. Re-addition of IL-7 to cytokine deprived T-cells restored HXKII gene expression within two hours. This increase in HXKII expression correlated with an increase in glucose uptake. In contrast, gene expression of the glucose transporter GLUT-1 increased after sixty hours of IL-7 readdition to deprived cells, and the gene expression of phospho-fructokinase (PFK) in response to IL-7 showed minimal differences. Inhibition of HXKII activity, using a specific inhibitor, Bromo-pyruvate, decreased glucose uptake in presence, but not the absence, of IL-7 while overexpression of HXKII restored glucose uptake in the absence of IL-7. In summary, we conclude that IL-7 controls glucose uptake in T-lymphocytes by regulating the gene expression of HXKII, suggesting a novel mechanism by which IL-7 supports glucose metabolism in T-cells.
