1. Lack of glucose recycling between endoplasmic reticulum and cytoplasm underlies cellular dysfunction in glucose-6-phosphatase-β–deficient neutrophils in a congenital neutropenia syndrome
- Author
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Janice Y. Chou, Yuk Yin Cheung, Philip M. Murphy, Suk See De Ravin, David H. McDermott, Hyun Sik Jun, Brian C. Mansfield, and Young Mok Lee
- Subjects
Male ,Cytoplasm ,Neutropenia ,Adolescent ,Neutrophils ,Glucose uptake ,Immunology ,G6PC3 ,Apoptosis ,Pentose phosphate pathway ,Glycogen Storage Disease Type I ,Endoplasmic Reticulum ,Biochemistry ,Phagocytes, Granulocytes, and Myelopoiesis ,Mice ,Adenosine Triphosphate ,Stress, Physiological ,medicine ,Animals ,Humans ,Lactic Acid ,Annexin A5 ,Child ,Mice, Knockout ,Glucose Transporter Type 1 ,NADPH oxidase ,biology ,Caspase 3 ,Endoplasmic reticulum ,NADPH Oxidases ,Cell Biology ,Hematology ,Syndrome ,medicine.disease ,Cell biology ,Mice, Inbred C57BL ,Glucose ,biology.protein ,Unfolded protein response ,Glucose-6-Phosphatase ,Female ,Glucose 6-phosphatase - Abstract
G6PC3 deficiency, characterized by neutropenia and neutrophil dysfunction, is caused by deficiencies in the endoplasmic reticulum (ER) enzyme glucose-6-phosphatase-β (G6Pase-β or G6PC3) that converts glucose-6-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 G6Pase-β in neutrophils remains unknown. We hypothesized that the ER recycles G6Pase-β–generated glucose to the cytoplasm, thus regulating the amount of available cytoplasmic glucose/G6P in neutrophils. Accordingly, a G6Pase-β deficiency 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, G6Pase-β is essential for normal energy homeostasis. A G6Pase-β deficiency prevents recycling of ER glucose to the cytoplasm, leading to neutrophil dysfunction.
- Published
- 2010