Lack of glucose recycling between endoplasmic reticulum and cytoplasm underlies cellular dysfunction in glucose-6-phosphatase-beta-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-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.
Jun
Hyun Sik
HS
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.
Lee
Young Mok
YM
Cheung
Yuk Yin
YY
McDermott
David H
DH
Murphy
Philip M
PM
De Ravin
Suk See
SS
Mansfield
Brian C
BC
Chou
Janice Y
JY
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
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