title: Control of hepatic nuclear superoxide production by glucose 6-phosphate dehydrogenase and NADPH oxidase-4.
abstract: Redox-regulated signal transduction is coordinated by spatially controlled production of reactive oxygen species within subcellular compartments. The nucleus has long been known to produce superoxide (O(2)(·-)); however, the mechanisms that control this function remain largely unknown. We have characterized molecular features of a nuclear superoxide-producing system in the mouse liver. Using electron paramagnetic resonance, we investigated whether several NADPH oxidases (NOX1, 2, and 4) and known activators of NOX (Rac1, Rac2, p22(phox), and p47(phox)) contribute to nuclear O(2)(·-) production in isolated hepatic nuclei. Our findings demonstrate that NOX4 most significantly contributes to hepatic nuclear O(2)(·-) production that utilizes NADPH as an electron donor. Although NOX4 protein immunolocalized to both nuclear membranes and intranuclear inclusions, fluorescent detection of NADPH-dependent nuclear O(2)(·-) predominantly localized to the perinuclear space. Interestingly, NADP(+) and G6P also induced nuclear O(2)(·-) production, suggesting that intranuclear glucose-6-phosphate dehydrogenase (G6PD) can control NOX4 activity through nuclear NADPH production. Using G6PD mutant mice and G6PD shRNA, we confirmed that reductions in nuclear G6PD enzyme decrease the ability of hepatic nuclei to generate O(2)(·-) in response to NADP(+) and G6P. NOX4 and G6PD protein were also observed in overlapping microdomains within the nucleus. These findings provide new insights on the metabolic pathways for substrate regulation of nuclear O(2)(·-) production by NOX4.
authors.affiliation: Department of Anatomy and Cell Biology, College of Medicine, The University of Iowa, Iowa City, Iowa 52242, USA.
authors.forename: Netanya Y
authors.initials: NY
authors.lastname: Spencer
authors.forename: Ziying
authors.initials: Z
authors.lastname: Yan
authors.forename: Ryan L
authors.initials: RL
authors.lastname: Boudreau
authors.forename: Yulong
authors.initials: Y
authors.lastname: Zhang
authors.forename: Meihui
authors.initials: M
authors.lastname: Luo
authors.forename: Qiang
authors.initials: Q
authors.lastname: Li
authors.forename: Xin
authors.initials: X
authors.lastname: Tian
authors.forename: Ajay M
authors.initials: AM
authors.lastname: Shah
authors.forename: Robin L
authors.initials: RL
authors.lastname: Davisson
authors.forename: Beverly
authors.initials: B
authors.lastname: Davidson
authors.forename: Botond
authors.initials: B
authors.lastname: Banfi
authors.forename: John F
authors.initials: JF
authors.lastname: Engelhardt
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism*; D002645:Chickens; D004578:Electron Spin Resonance Spectroscopy; D020536:Enzyme Activators / Q000378:metabolism; D005954:Glucosephosphate Dehydrogenase / Q000235:genetics / Q000378:metabolism*; D008099:Liver / Q000166:cytology / Q000201:enzymology*; D051379:Mice; D018345:Mice, Knockout; D009249:NADP / Q000378:metabolism; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011817:Rabbits; D013481:Superoxides / Q000378:metabolism*
chemical_list: D020536:Enzyme Activators; D009687:Nuclear Proteins; D013481:Superoxides; D009249:NADP; D005954:Glucosephosphate Dehydrogenase; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases; C422943:Nox4 protein, mouse