PHAGOCYTES, GRANULOCYTES, AND MYELOPOIESIS Lack of glucose recycling between endoplasmic reticulum and cytoplasm underlies cellular dysfunction in glucose-6-phosphatase- –deficient neutrophils in a congenital neutropenia syndrome

G6PC3 deficiency, characterized by neutropenia and neutrophil dysfunction, is caused by deficiencies in the endoplasmic reticulum (ER) enzyme glucose-6-phosphatase(G6Paseor G6PC3) that converts glucose6-phosphate (G6P) into glucose, the primary energy source of neutrophils. Enhanced neutrophil ER stress and apoptosis underlie neutropenia in G6PC3 deficiency, but the exact functional role of G6Pasein neutrophils remains unknown. We hypothesized that the ER recycles G6Pase–generated glucose to the cytoplasm, thus regulating theamountofavailablecytoplasmicglucose/ G6Pin neutrophils.Accordingly, a G6Pasedeficiency would impair glycolysis and hexose monophosphate shunt activities leading to reductions in lactate production, adenosine-5 -triphosphate (ATP) production, and reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity. Using annexin V–depleted neutrophils, we show that glucose transporter-1 translocation is impaired in neutrophils from G6pc3 / mice and G6PC3-deficient patients along with impaired glucose uptake in G6pc3 / neutrophils. Moreover, levels of G6P, lactate, and ATP are markedly lower in murine and human G6PC3-deficient neutrophils, compared with their respective controls. In parallel, the expression of NADPH oxidase subunits and membrane translocation of p47phox are down-regulated in murine and human G6PC3-deficient neutrophils. The results establish that in nonapoptotic neutrophils, G6Paseis essential for normal energy homeostasis. A G6Pasedeficiency prevents recycling of ER glucose to the cytoplasm, leading to neutrophil dysfunction. (Blood. 2010;116(15):2783-2792)