Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.6.3.1 (NADPH oxidase)
11,281 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Solar ultraviolet A (UVA) radiation induces many responses in skin including oxidative stress, DNA damage, inflammation, and skin cancer. Smith-Lemli-Opitz syndrome (SLO-S) patients show dramatically enhanced immediate (5 min) and extended (24-48 h) skin inflammation in response to low UVA doses compared to normal skin. Mutations in Delta7-dehydrocholesterol reductase, which converts 7-dehydrocholesterol to cholesterol, produces high levels of 7-dehydrocholesterol in SLO-S patient's serum. Since 7-dehydrocholesterol is more rapidly oxidized than cholesterol, we hypothesized that 7-dehydrocholesterol enhances UVA-induced oxidative stress leading to keratinocyte death and inflammation. When keratinocytes containing high 7-dehydrocholesterol and low cholesterol were exposed to UVA (10 J/cm2), eightfold greater reactive oxygen species (ROS) were produced than in normal keratinocytes after 15 min. UVA induced 7-dehydrocholesterol concentration-dependent cell death at 24 h. These responses were inhibited by antioxidants, reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor (diphenyleneiodonium) and a mitochondria-specific radical quencher. Cell death was characterized by activation of caspases-3, -8, and -9 and by phosphatidylserine translocation. Studies using antioxidants and specific caspase inhibitors indicated that activation of caspase-8, but not caspase-9, mediates ROS-dependent caspase-3 activation and suggested that ROS from NADPH oxidase activate caspase-8. These results support a ROS-mediated apoptotic mechanism for the enhanced UVA-induced inflammation in SLO-S patients.
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PMID:Ultraviolet A induces apoptosis via reactive oxygen species in a model for Smith-Lemli-Opitz syndrome. 1645 95

Mitochondrial P450 type enzymes catalyze central steps in steroid biosynthesis, including cholesterol conversion to pregnenolone, 11beta and 18 hydroxylation in glucocorticoid and mineralocorticoid synthesis, C-27 hydroxylation of bile acids, and 1alpha and 24 hydroxylation of 25-OH-vitamin D. These monooxygenase reactions depend on electron transfer from NADPH via FAD adrenodoxin reductase and 2Fe-2S adrenodoxin. These systems can function as a futile NADPH oxidase, oxidizing NADPH in absence of substrate, and leak electrons via adrenodoxin and P450 to O(2), producing superoxide and other reactive oxygen species (ROS). The degree of uncoupling depends on the P450 and steroid substrate. Studies with purified proteins and overexpression in cultured cells show consistently that adrenodoxin, but not reductase, is responsible for ROS production that can lead to apoptosis. In the ovary and corpus luteum, antioxidant enzyme activities superoxide dismutase, catalase, and glutathione peroxidase parallel steroidogenesis. Antioxidant beta-carotene, alpha-tocopherol, and ascorbate can protect against oxidative damages of P450 systems. In testis Leydig cells, steroidogenesis is associated with aging of the steroidogenic capacity.
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PMID:Antioxidant protective mechanisms against reactive oxygen species (ROS) generated by mitochondrial P450 systems in steroidogenic cells. 1668 56

3-Hydroxy-3-methylglutaryl CoA reductase inhibitors decrease cardiovascular morbidity in diabetic patients, but the mechanism is unclear. We studied the actions of simvastatin (SIM) in enhancing NO bioavailability and reducing oxidative stress in coronary vessels from diabetic rats and in rat coronary artery endothelial cells (RCAEC) exposed to high glucose. Coronary arteries isolated from diabetic rats showed decreases in acetylcholine (ACh)-mediated maximal relaxation from 81.0 +/- 4.5% in controls to 43.5 +/- 7.6% at 4 weeks and 22.3 +/- 0.6% at 10 weeks of diabetes. This effect was associated with oxidative stress in coronary vessels as shown by dichlorofluorescein (DCF) imaging and nitrotyrosine labeling. Diabetes also reduced trans-coronary uptake of [(3)H]l-arginine. Supplemental l-arginine (50 mg/kg/day p.o.) did not improve coronary vasorelaxation to ACh. However, SIM treatment (5 mg/kg/day subcutaneously) improved maximal ACh relaxation to 65.8 +/- 5.1% at 4 weeks and 47.1 +/- 3.9% at 10 weeks. Coronary arteries from rats treated with both SIM and l-arginine demonstrated the same maximal relaxation to ACh (66.1 +/- 3%) as SIM alone. Mevalonate and l-NAME (N(omega)-nitro-l-arginine methyl ester hydrochloride) inhibited the response to ACh in SIM-treated diabetic rats. Coronary arteries from all groups relaxed similarly to sodium nitroprusside. SIM increased endothelial NO synthase protein levels and blocked diabetes-induced increases in DCF and nitrotyrosine labeling in diabetic coronary vessels. SIM treatment restored normal NO levels in media from high-glucose-treated RCAEC and plasma of diabetic rat. Treatment with SIM or the NADPH oxidase inhibitor apocynin also blocked high-glucose-induced increases in reactive oxygen species and superoxide formation in RCAEC. Taken together, these data suggest that SIM improves diabetes-induced coronary dysfunction by reducing oxidative stress and increasing NO bioavailability.
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PMID:Simvastatin improves diabetes-induced coronary endothelial dysfunction. 1684 25

The role of H2O2 as a second messenger in signal transduction pathways is well established. We show here that the NADPH oxidase-dependent production of O2*(-) and H2O2 or respiratory burst in alveolar macrophages (AM) (NR8383 cells) is required for ADP-stimulated c-Jun phosphorylation and the activation of JNK1/2, MKK4 (but not MKK7) and apoptosis signal-regulating kinase-1 (ASK1). ASK1 binds only to the reduced form of thioredoxin (Trx). ADP induced the dissociation of ASK1/Trx complex and thus resulted in ASK1 activation, as assessed by phosphorylation at Thr845, which was enhanced after treatment with aurothioglucose (ATG), an inhibitor of Trx reductase. While dissociation of the complex implies Trx oxidation, protein electrophoretic mobility shift assay detected oxidation of Trx only after bolus H2O2 but not after ADP stimulation. These results demonstrate that the ADP-stimulated respiratory burst activated the ASK1-MKK4-JNK1/c-Jun signaling pathway in AM and suggest that transient and localized oxidation of Trx by the NADPH oxidase-mediated generation of H2O2 may play a critical role in ASK1 activation and the inflammatory response.
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PMID:The ADP-stimulated NADPH oxidase activates the ASK-1/MKK4/JNK pathway in alveolar macrophages. 1701 65

Nitric oxide synthases (NOS) are flavoheme enzymes with important roles in biology. The reductase domain of neuronal NOS (nNOSr) contains a widely conserved acidic residue (Asp(1393)) that is thought to facilitate hydride transfer between NADPH and FAD. Previously we found that the D1393V and D1393N mutations lowered the NO synthesis activity and the rates of heme and flavin reduction in full-length nNOS. To examine the mechanisms for these results in greater detail, we incorporated D1393V and D1393N substitutions into nNOSr along with a truncated NADPH-FAD domain construct (FNR) and characterized the mutants. D1393V nNOSr had markedly lower (<or=1000x) cytochrome c reductase, ferricyanide reductase, and NADPH oxidase activities than the wild type. D1393N nNOSr also had lower reductase activities (<or=10x) but had greater NADPH oxidase activity than that of the wild type, as did its FNR fragment. Both mutants had an altered interaction between FAD and the nicotinamide ring of NADP(+), slower flavin reduction by NADPH, altered FAD midpoint potentials, a normal CaM response, and, in one case (D1393N), faster flavin oxidation by O(2) and a lack of FMN shielding in response to NADPH binding. The results suggest that the two mutants have compromised catalysis for two different reasons. In D1393V nNOSr, hydride transfer from NADPH to FAD is so slow that it compromises all downstream electron-transfer events. In D1393N nNOSr, the increased oxidation of reduced flavins by O(2) and thermodynamic destabilization of the FAD semiquinone uncouples or limits electron transfer to an extent that it inhibits downstream catalysis. These effects are due in part to the mutations eliminating (D1393V) or altering (D1393N) the native side-chain hydrogen-bonding properties of Asp(1393) as well as removing its negative charge.
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PMID:Role of Asp1393 in catalysis, flavin reduction, NADP(H) binding, FAD thermodynamics, and regulation of the nNOS flavoprotein. 1702 14

The effect of estrogen on neointimal formation in injured rat arteries has been reported to be a sexual dimorphic effect. Recently, it has been reported that 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) exhibit vasoprotective effects, which are independent of their cholesterol-lowering effects. In this study, we examined the gender differences of atorvastatin's effect on neointimal formation in balloon-injured rat arteries. Male and female Sprague Dawley rats underwent gonadectomy and balloon injury of the carotid artery. Ovariectomized female, as well as intact and castrated male, rats exhibited marked neointimal formation. Treatment with atorvastatin significantly reduced neointimal formation at day 14 (14 days after injury) and NADPH oxidase-dependent superoxide production at day 2 in ovariectomy, but not in intact and castrated males. In ovariectomized rats, 7 days of atorvastatin treatment from days -3 to 3 but not from days 7 to 14 suppressed neointimal formation at day 14. In this study, we showed that atorvastatin's effect on neointimal formation was female-specific and was more marked in ovariectomized female rats. NADPH oxidase-dependent superoxide production may be involved in the mechanism of the sexual dimorphic response seen in response to atorvastatin treatment. Furthermore, the results suggest the importance of treatment in the early phase after vascular injury.
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PMID:Gender difference of atorvastatin's vasoprotective effect in balloon-injured rat carotid arteries. 1705 30

The role of Leu505 of Nox2 on the NADPH oxidase activation process was investigated. An X-CGD PLB-985 cell line expressing the Leu505Arg Nox2 mutant was obtained, exactly mimicking the phenotype of a previously published X91+-CGD case. In a reconstituted cell-free system (CFS), NADPH oxidase and iodonitrotetrazolium (INT) reductase activities were partially maintained concomitantly with a partial cytosolic factors translocation to the plasma membrane. This suggests that assembly and electron transfer from NADPH occurred partially in the Leu505Arg Nox2 mutant. Moreover, in a simplified CFS using purified mutant cytochrome b558 and recombinant p67phox, p47phox, and Rac1proteins, we found that the Km for NADPH and for NADH was about three times higher than those of purified WT cytochrome b558, indicating that the Leu505Arg mutation induces a slight decrease of the affinity for NADPH and NADH. In addition, oxidase activity can be extended by increasing the amount of p67phox in the simplified CFS assay. However, the maximal reconstituted oxidase activity using WT purified cytochrome b558 could not be reached using mutant cytochrome b558. In a three-dimensional model of the C-terminal tail of Nox2, Leu505 appears to have a strategic position just at the entry of the NADPH binding site and at the end of the alpha-helical loop (residues 484-504), a potential cytosolic factor binding region. The Leu505Arg mutation seems to affect the oxidase complex activation process through alteration of cytosolic factors binding and more particularly the p67phox interaction with cytochrome b558, thus affecting NADPH access to its binding site.
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PMID:Leu505 of Nox2 is crucial for optimal p67phox-dependent activation of the flavocytochrome b558 during phagocytic NADPH oxidase assembly. 1706 Mar 62

Ferredoxin:NADP oxidoreductases (FNRs) constitute a family of flavoenzymes that catalyze the exchange of reducing equivalents between one-electron carriers and the two-electron-carrying NADP(H). The main role of FNRs in cyanobacteria and leaf plastids is to provide the NADPH for photoautotrophic metabolism. In root plastids, a distinct FNR isoform is found that has been postulated to function in the opposite direction, providing electrons for nitrogen assimilation at the expense of NADPH generated by heterotrophic metabolism. A multiple gene family encodes FNR isoenzymes in plants, whereas there is only one FNR gene (petH) in cyanobacteria. Nevertheless, we detected two FNR isoforms in the cyanobacterium Synechocystis sp. strain PCC6803. One of them (FNR(S) approximately 34 kDa) is similar in size to the plastid FNR and specifically accumulates under heterotrophic conditions, whereas the other one (FNR(L) approximately 46 kDa) contains an extra N-terminal domain that allows its association with the phycobilisome. Site-directed mutants allowed us to conclude that the smaller isoform, FNR(S), is produced from an internal ribosome entry site within the petH ORF. Thus we have uncovered a mechanism by which two isoforms are produced from a single gene, which is, to our knowledge, novel in photosynthetic bacteria. Our results strongly suggest that FNR(L) is an NADP(+) reductase, whereas FNR(S) is an NADPH oxidase.
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PMID:A second isoform of the ferredoxin:NADP oxidoreductase generated by an in-frame initiation of translation. 1711 80

Lysophosphatidic acid (LPA), a product generated during oxidative modification of low-density lipoprotein (LDL) and a major lipid extracted from human atherosclerotic plaques, has been shown to elicit smooth muscle cell (SMC) proliferation and inflammation, thereby being involved in atherogenesis. Recently, statins, an inhibitor of 3-hydroxy-methylglutaryl coenzyme A (HMG-CoA) reductase, have been reported to reduce the risk of cardiovascular events and slows the progression of atherosclerosis, at least partly, via pleiotropic effects. However, the effect of statin on the LPA-signaling in SMCs remains to be elucidated. In this study, we investigated whether and how pitavastatin could inhibit the LPA-induced proliferation and monocyte chemoattractant protein-1 (MCP-1) expression in cultured human aortic SMCs. LPA dose-dependently increased intracellular reactive oxygen species (ROS) generation in SMCs, which was blocked by diphenylene iodonium (DPI), an inhibitor of NADPH oxidase or pitavastatin. The anti-oxidative property of pitavastatin was prevented by simultaneous treatment of geranylgeranyl pyrophosphate. Furthermore, overexpression of dominant negative Rac-1 mutant was found to inhibit the LPA-induced ROS generation in SMCs. LPA induced Rac-1 activation in SMCs, which was suppressed by pitavastatin or LPA receptor antagonist. Pitavastatin, DPI, and an anti-oxidant N-acetylcysteine inhibited the LPA-induced proliferation and MCP-1 gene expression in SMCs. These results suggest that pitavastatin could block the LPA-induced proliferation and MCP-1 expression in SMCs by suppressing Rac-1-mediated NADPH oxidase-dependent ROS generation. Our present study provides a novel beneficial aspect of pitavastatin; pitavastatin may act as a blocker of the LPA-signaling in SMCs.
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PMID:Pitavastatin inhibits lysophosphatidic acid-induced proliferation and monocyte chemoattractant protein-1 expression in aortic smooth muscle cells by suppressing Rac-1-mediated reactive oxygen species generation. 1717 55

Pulmonary fibrosis is one of the most severe consequences of exposure to paraquat, an herbicide that causes rapid alveolar inflammation and epithelial cell damage. Paraquat is known to induce toxicity in cells by stimulating oxygen utilization via redox cycling and the generation of reactive oxygen intermediates. However, the enzymatic activity mediating this reaction in lung cells is not completely understood. Using self-referencing microsensors, we measured the effects of paraquat on oxygen flux into murine lung epithelial cells. Paraquat (10-100 microm) was found to cause a 2-4-fold increase in cellular oxygen flux. The mitochondrial poisons cyanide, rotenone, and antimycin A prevented mitochondrial- but not paraquat-mediated oxygen flux into cells. In contrast, diphenyleneiodonium (10 microm), an NADPH oxidase inhibitor, blocked the effects of paraquat without altering mitochondrial respiration. NADPH oxidases, enzymes that are highly expressed in lung epithelial cells, utilize molecular oxygen to generate superoxide anion. We discovered that lung epithelial cells possess a distinct cytoplasmic diphenyleneiodonium-sensitive NAD(P)H:paraquat oxidoreductase. This enzyme utilizes oxygen, requires NADH or NADPH, and readily generates the reduced paraquat radical. Purification and sequence analysis identified this enzyme activity as thioredoxin reductase. Purified paraquat reductase from the cells contained thioredoxin reductase activity, and purified rat liver thioredoxin reductase or recombinant enzyme possessed paraquat reductase activity. Reactive oxygen intermediates and subsequent oxidative stress generated from this enzyme are likely to contribute to paraquat-induced lung toxicity.
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PMID:Paraquat increases cyanide-insensitive respiration in murine lung epithelial cells by activating an NAD(P)H:paraquat oxidoreductase: identification of the enzyme as thioredoxin reductase. 1722 25


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