title: Lack of glucose recycling between endoplasmic reticulum and cytoplasm underlies cellular dysfunction in glucose-6-phosphatase-beta-deficient neutrophils in a congenital neutropenia syndrome.
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 p47(phox) 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.
authors.affiliation: Section on Cellular Differentiation, Program on Developmental Endocrinology and Genetics, National Institute of Child Health and Human Development, National Institutes of Health (NIH), Bethesda, MD, USA.
authors.forename: Hyun Sik
authors.initials: HS
authors.lastname: Jun
authors.forename: Young Mok
authors.initials: YM
authors.lastname: Lee
authors.forename: Yuk Yin
authors.initials: YY
authors.lastname: Cheung
authors.forename: David H
authors.initials: DH
authors.lastname: McDermott
authors.forename: Philip M
authors.initials: PM
authors.lastname: Murphy
authors.forename: Suk See
authors.initials: SS
authors.lastname: De Ravin
authors.forename: Brian C
authors.initials: BC
authors.lastname: Mansfield
authors.forename: Janice Y
authors.initials: JY
authors.lastname: Chou
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000293:Adolescent; D000818:Animals; D017304:Annexin A5 / Q000378:metabolism; D017209:Apoptosis; D053148:Caspase 3 / Q000378:metabolism; D002648:Child; D003593:Cytoplasm / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005260:Female; D005947:Glucose / Q000378:metabolism*; D051272:Glucose Transporter Type 1 / Q000378:metabolism; D005952:Glucose-6-Phosphatase / Q000235:genetics / Q000378:metabolism*; D005953:Glycogen Storage Disease Type I / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D019344:Lactic Acid / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D019255:NADPH Oxidases / Q000378:metabolism; D009503:Neutropenia / Q000151:congenital* / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D009504:Neutrophils / Q000378:metabolism* / Q000473:pathology; D013312:Stress, Physiological; D013577:Syndrome
chemical_list: D017304:Annexin A5; D051272:Glucose Transporter Type 1; D019344:Lactic Acid; D000255:Adenosine Triphosphate; D019255:NADPH Oxidases; D005952:Glucose-6-Phosphatase; C492193:G6PC3 protein, human; D053148:Caspase 3; D005947:Glucose