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:1.6.99.6 (NADPH oxidase)
10,295 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Oxidative stress contributes to the pathogenesis of atherosclerosis. p22phox-based NAD(P)H oxidases exist in the vessel wall, acting as important superoxide-generating systems in the vasculature. Some studies have identified reduced atherosclerosis in the presence of the C242T CYBA polymorphism, whereas others have not. Because vascular p22phox is identical to neutrophil p22phox, we studied the association between the C242T, A640G, and -930A/G CYBA polymorphisms and the quantity of superoxide produced from neutrophils isolated from healthy adults to determine if these polymorphisms had any functional impact on NADPH oxidase function. Neutrophils were isolated from 90 subjects by Percoll density gradient centrifugation. Genotypes were determined by polymerase chain reaction (PCR) and restriction mapping, as well as real-time PCR. The oxidative burst was stimulated with phorbol 12-myristate 13-acetate. Superoxide was quantified using the superoxide dismutase inhibitable oxidation of the spin probe hydroxylamine 1-hydroxy-3-carboxy-pyrrolidine, detected by electron paramagnetic resonance. Superoxide production was significantly affected by the C242T polymorphism, being 8.7+/-0.7, 7.9+/-0.6, and 5.9+/-1.2 micromol/L per minute per 10(6) neutrophils for the C242T CC, CT, and TT genotypes, respectively (P<0.05). In contrast, the A640G and the -930A/G polymorphisms did not alter the neutrophil respiratory burst. Phagocytic respiratory burst activity in homozygous individuals with the T allele of the C242T CYBA polymorphism is significantly lower than of wild-type carriers and heterozygous individuals. Because p22phox exists in both the neutrophil and vessel wall, vascular oxidative stress is likely diminished in individuals with this polymorphism.
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PMID:C242T CYBA polymorphism of the NADPH oxidase is associated with reduced respiratory burst in human neutrophils. 1507 63

Neutrophil functions are impaired in patients with diabetes mellitus. Bacterial phagocytosis and oxidative burst activity are reduced at high glucose concentrations in diabetic patients. Defects in neutrophil oxidative burst capacity are of multifactorial origin in diabetes mellitus and correlate with glucose levels. It has been reported that neutrophil NADPH oxidase activity is impaired and superoxide production is reduced in diabetic patients with or without any infections. Nicotinamide is a vitamin B3 derivative and a NAD precursor with immunomodulatory effects. In vitro studies demonstrated that nicotinamide increases NAD and NADH content of beta cells. The authors hypothesized that nicotinamide may restore the impaired oxidative burst capacity of neutrophils in diabetic patients by increasing the NADH content as an electron donor and possibly through NADPH oxidase activity of the cell. In order to test the hypothesis, this placebo-controlled and open study was designed to evaluate neutrophil functions in infection-free poorly controlled type 2 diabetic patients as compared to healthy subjects and assess the effects of nicotinamide on neutrophil phagocytosis as well as oxidative burst activity. Thirty patients with type 2 diabetes mellitus were enrolled in the study. Sixteen were females and 14 were males, with a mean age 58 +/- 10. All patients were on sulphonylurea treatment and their hemoglobin A(1c) (HbA(1c)) levels were above 7.5%. The control group consisted of 10 voluntary healthy subjects. Diabetic and control subjects were not significantly different in terms of age, body mass index (BMI), leucocyte and neutrophil counts, C-reactive protein (CRP) level, and erythrocyte sedimentation rate (ESR), but HbA(1c) and fasting glucose levels were significantly higher in patients with diabetes mellitus. Phagocytic activity and respiratory burst indexes were measured by flow cytometric analyses as previously described by Rothe and Valet (Methods Enzyml., 233, 539-548, 1994) and compared in diabetic subjects and healthy controls. Diabetic patients were grouped to receive either 50 mg/kg oral nicotinamide (n = 15) or placebo (n = 15) for a period of 1 month. The 2 groups did not differ in terms of treatment, frequency of hypertension, BMI, diabetes duration, age, fasting plasma glucose (FPG), HbA(1c), CRP, ESR, polymorphonuclear leukocyte (PNL) and neutrophil counts. Neutrophil functions were reassessed after the treatment period. Phagocytic activity represented as indexes were lower in diabetic patients when compared to healthy subjects, but the differences were not statistically significant (P >.05). Patients with diabetes mellitus had significantly lower oxidative burst indexes when compared to healthy controls (P values <.05). In diabetic patients, a negative correlation between neutrophil functions and HbA(1c) was found which was not statistically significant (P values >.05). Phagocytic indexes were similar in nicotinamide and placebo groups after treatment period (P >.05). But oxidative burst activity in patients receiving nicotinamide was greater when compared with placebo and the difference was statistically significant at 30 and 45 minutes (P values.04 and.03). This effect of nicotinamide may be due to increased NADH content and NADPH oxidase activity of the cell, which needs to be further studied. Impaired neutrophil functions may aggravate various infections in patients with diabetes mellitus and blood glucose regulation is an important target of treatment to improve neutrophil functions. But nicotinamide treatment may help to improve prognosis in diabetic patients with severe infections.
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PMID:Nicotinamide effects oxidative burst activity of neutrophils in patients with poorly controlled type 2 diabetes mellitus. 1520 86

Vascular endothelial activation is an early step during leukocyte/endothelial adhesion and transendothelial leukocyte migration in inflammatory states. Leukocyte transmigration occurs through intercellular gaps between endothelial cells. Vascular endothelial cadherin (VE-cadherin) is a predominant component of endothelial adherens junctions that regulates intercellular gap formation. We found that tumor necrosis factor (TNF) caused tyrosine phosphorylation of VE-cadherin, separation of lateral cell-cell junctions, and intercellular gap formation in human umbilical vein endothelial cell (HUVEC) monolayers. These events appear to be regulated by intracellular oxidant production through endothelial NAD(P)H (nicotinamide adenine dinucleotide phosphate) oxidase because antioxidants and expression of a transdominant inhibitor of the NADPH oxidase, p67(V204A), effectively blocked the effects of TNF on all 3 parameters of junctional integrity. Antioxidants and p67(V204A) also decreased TNF-induced JNK activation. Dominant-negative JNK abrogated VE-cadherin phosphorylation and junctional separation, suggesting a downstream role for JNK. Finally, adenoviral delivery of the kinase dead PAK1(K298A) decreased TNF-induced JNK activation, VE-cadherin phosphorylation, and lateral junctional separation, consistent with the proposed involvement of PAK1 upstream of the NADPH oxidase. Thus, PAK-1 acts in concert with oxidase during TNF-induced oxidant production and loss of endothelial cell junctional integrity.
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PMID:NADPH oxidase mediates vascular endothelial cadherin phosphorylation and endothelial dysfunction. 1527 97

Mitochondrial respiration plays an important role in optimizing photosynthetic efficiency in plants. As yet, the mechanisms by which plant mitochondria sense and respond to changes in the environment are unclear, particularly when exposed to light. Here we describe the characterization of the Chlamydomonas reinhardtii mutant stm6, which was identified on the basis of impaired state transitions, a mechanism that regulates light harvesting in the chloroplast. The gene disrupted in stm6, termed Moc1, encodes a homologue of the human mitochondrial transcription termination factor (mTERF). MOC1 is targeted to the mitochondrion, and its expression is up-regulated in response to light. Loss of MOC1 causes a high light-sensitive phenotype and disrupts the transcription and expression profiles of the mitochondrial respiratory complexes causing, as compared with wild type, light-mediated changes in the expression levels of nuclear and mitochondrial encoded cytochrome c oxidase subunits and ubiquinone-NAD subunits. The absence of MOC1 leads to a reduction in the levels of cytochrome c oxidase and of rotenone-insensitive external NADPH dehydrogenase activities of the mitochondrial respiratory electron transfer chain. Overall, we have identified a novel mitochondrial factor that regulates the composition of the mitochondrial respiratory chain in the light so that it can act as an effective sink for reductant produced by the chloroplast.
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PMID:The nucleus-encoded protein MOC1 is essential for mitochondrial light acclimation in Chlamydomonas reinhardtii. 1544 40

Two-photon microscopy allows determination of UV-excitable fluorophores using long-wavelength light. We aimed to determine NAD(P)H autofluorescence as a measure for macrophage NADPH-oxidase activation. RAW264.7 macrophages were grown on glass coverslips and kept in HBSS for microscopic investigation. Cells were excited with 710 nm light and NAD(P)H autofluorescence was detected. Glucose as well as NaCN evoked an increase of NAD(P)H autofluorescence. Activators of NADPH oxidase lead to significantly decreased NAD(P)H autofluorescence. Therefore, this work shows the suitability of two-photon microscopy as a non-invasive method determining changes in phagocyte NAD(P)H upon activation.
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PMID:Non-invasive live-cell measurement of changes in macrophage NAD(P)H by two-photon microscopy. 1558 5

Modified low-density lipoprotein (LDL) induces reactive oxygen species (ROS) production by vascular cells. It is unknown if specific oxidized components in these LDL particles such as oxidized-1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphorylcholine (ox-PAPC) can stimulate ROS production. Bovine aortic endothelial cells (BAEC) were incubated with ox-PAPC (50 microg/ml). At 4 h, ox-PAPC significantly enhanced the rate of O2- production. Pretreatment of BAEC in glucose-free Dulbecco's modified Eagle's medium plus 10 mM 2-deoxyglucose (2-DOG), the latter being an antimetabolite that blocks NADPH production by the pentose shunt, significantly reduced the rate of O2- production. The intensity of NAD(P)H autofluorescence decreased by 28 +/- 12% in BAEC incubated with ox-PAPC compared to untreated cells, with a further decrease in the presence of 2-DOG. Ox-PAPC also increased Nox4 mRNA expression by 2.4-fold +/- 0.1 while pretreatment of BAEC with the small interfering RNA (siNox4) attenuated Nox4 RNA expression. Ox-PAPC further reduced the level of glutathione while pretreatment with apocynin (100 microM) restored the GSH level (control = 22.54 +/- 0.23, GSH = 18.06 +/- 0.98, apocynin = 22.55 +/- 0.60, ox-PAPC + apocynin = 21.17 +/- 0.36 nmol/10(6) cells). Treatment with ox-PAPC also increased MMP-2 mRNA expression accompanied by a 1.5-fold increase in MMP-2 activity. Ox-PAPC induced vascular endothelial OO2-(.) production that appears to be mediated largely by NADPH oxidase activity.
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PMID:Oxidized-1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphorylcholine induces vascular endothelial superoxide production: implication of NADPH oxidase. 1627 86

Some properties of microsomal electron transfer chains, dependent for oxidase activity on addition of NADH or NADPH, duroquinone, and oxygen (L. De Luca et al., 1984, Plant Sci Lett 36: 93-98) are described. Activity is characterized by negatively cooperative kinetics toward reduced pyridine nucleotides, with limiting K(m) of 10 to 50 micromolar at pH 7.0 (increasing at lower pH), as well as toward duroquinone with limiting K(m) of 100 to 400 micromolar regardless of pH. Molecular oxygen is reduced by the enzyme complex with S(0.5) of about 30 micromolar and production of H(2)O and H(2)O(2), without superoxide involvement. The ratio NAD(P)H:O(2) averages 1.35 in the presence of KCN and 1.85 in its absence. The pyridine nucleotide specificity of the dehydrogenases has been investigated by kinetic competition experiments. Some enzyme heterogeneity was established for all preparations. At least two enzymes are detectable in plasma membrane-enriched fractions: a major NAD(P)H dehydrogenase having an acid pH optimum, and an NADPH dehydrogenase active around neutrality. Addition of Triton X-100 strongly enhances the activity over most of the pH scale, but depresses it increasingly at pH values higher than 8.0, to the effect that pH profile shows, under these conditions, a major peak at about pH 5.8 for both NADH and NADPH oxidase. Results with endoplasmic reticulum preparations are similar, except that they suggest the presence of still more activities at and above pH 7. The results are interpreted in terms of different complexes catalyzing electron transfer from NAD(P)H to O(2) without release of intermediates.
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PMID:Kinetic characterization of reduced pyridine nucleotide dehydrogenases (duroquinone-dependent) in cucurbita microsomes. 1666 30

Activated matrix metalloproteinases (MMPs) in patients with acute coronary syndromes may contribute to plaque destabilization. Tumor necrosis factor-alpha (TNF-alpha) enhances NAD (P) H oxidase-dependent reactive oxygen species (ROS) formation and ROS induce MMP-2. In the present study, the effects of a potent water-soluble antioxidant, salvianolic acid B (SalB), derived from a Chinese herb, Salvia miltiorrhiza, on the expression of MMP-2 by TNF-alpha-treated human aortic smooth muscle cells (HASMCs) were investigated. In this study, salvianolic acid B scavenged H2O2 in a dose-dependent manner in test tube. We found that SalB, as well as NADPH oxidase inhibitors, DPI or apocynin, and antioxidant NAC, inhibited TNF-alpha-induced MMP-2 mRNA, protein expression, and gelatinolytic activity in HASMCs in a concentration-dependent manner. We also observed a dose-dependent decrease in ROS production and NADPH oxidase activity induced by TNF-alpha in the presence of SalB. SalB also significantly inhibited angiotensin II or H2O2-induced MMP-2 mRNA and protein expression and gelatinolytic activity in HASMCs. Our data point out that the importance of NADPH oxidase-dependent ROS generation in the control of SalB inhibition of TNF-alpha-induced MMP-2 expression and activity.
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PMID:Salvianolic acid B from Salvia miltiorrhiza inhibits tumor necrosis factor-alpha (TNF-alpha)-induced MMP-2 upregulation in human aortic smooth muscle cells via suppression of NAD(P)H oxidase-derived reactive oxygen species. 1671 3

Oxidative stress may be an important determinant of the severity of acute pancreatitis. One-electron reduction of oxidants generates reactive oxygen species (ROS) via redox cycling, whereas two-electron detoxification, e.g. by NAD(P)H:quinone oxidoreductase, does not. The actions of menadione on ROS production and cell fate were compared with those of a non-cycling analogue (2,4-dimethoxy-2-methylnaphthalene (DMN)) using real-time confocal microscopy of isolated perfused murine pancreatic acinar cells. Menadione generated ROS with a concomitant decrease of NAD(P)H, consistent with redox cycling. The elevation of ROS was prevented by the antioxidant N-acetyl-l-cysteine but not by the NADPH oxidase inhibitor diphenyliodonium. DMN produced no change in reactive oxygen species per se but significantly potentiated menadione-induced effects, probably via enhancement of one-electron reduction, since DMN was found to inhibit NAD(P)H:quinone oxidoreductase detoxification. Menadione caused apoptosis of pancreatic acinar cells that was significantly potentiated by DMN, whereas DMN alone had no effect. Furthermore, bile acid (taurolithocholic acid 3-sulfate)-induced caspase activation was also greatly increased by DMN, whereas DMN had no effect per se. These results suggest that acute generation of ROS by menadione occurs via redox cycling, the net effect of which is induction of apoptotic pancreatic acinar cell death. Two-electron detoxifying enzymes such as NAD(P)H:quinone oxidoreductase, which are elevated in pancreatitis, may provide protection against excessive ROS and exert an important role in determining acinar cell fate.
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PMID:Menadione-induced reactive oxygen species generation via redox cycling promotes apoptosis of murine pancreatic acinar cells. 1708 48

Biallelic inactivation of the von Hippel-Lindau tumor suppressor gene (VHL) is linked to the development of hereditary and sporadic renal cell carcinoma (RCC). In the absence of VHL, the alpha subunits of heterodimeric hypoxia-inducible transcription factors (HIF-1alpha and HIF-2alpha) are stabilized. Reactive oxygen species, generated by NAD(P)H oxidases, are involved in signaling cascades of malignant growth. We show that in VHL-deficient cells p22phox, Nox4 protein levels and NADPH-dependent superoxide generation are increased. Reintroduction of VHL into the VHL-deficient cells down-regulates the expression of p22phox and NADPH-dependent superoxide generation. Inhibition of the 26 S proteasome in VHL-expressing cells increased p22phox protein levels, which correlated with an increase of NADPH-dependent superoxide generation. We also show that p22phox co-immunoprecipitates with VHL in vivo. Moreover, p22phox is a target of ubiquitination. Importantly, in VHL-deficient cells, diphenyleneiodonium chloride (DPI), an inhibitor of Nox oxidases, decreased the expression of HIF-2alpha. Down-regulation of Nox1, Nox4, and p22phox expression by small interfering RNA also decreased HIF-2alpha protein expression and inhibited Akt and 4E-BP1 phosphorylation, suggesting that a translational mechanism is involved in maintaining HIF-2alpha in VHL-deficient cells. Colony formation by RCC 786-O in soft agar was markedly inhibited by DPI. Moreover, DPI significantly inhibited RCC 786-O tumor formation in athymic mice. Collectively, the data demonstrate that VHL protein exerts its tumor suppressor action, at least partially, via inhibition of p22phox-based Nox4/Nox1 NADPH oxidase-dependent reactive oxygen species generation.
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PMID:NAD(P)H oxidases regulate HIF-2alpha protein expression. 1720 Jan 23


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