Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.6.3.1 (NADPH oxidase)
 11,281 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An agonist-activated phospholipase D/phosphatidic acid phosphohydrolase (PAH) pathway was recently demonstrated in human neutrophils, and evidence suggests that phosphatidic acid (PA) and/or diradylglycerol (DG) generated from this pathway participates in activation of the O2(-)-generating respiratory burst. We have used a series of cationic amphiphilic compounds (sphingosine, propranolol, chlorpromazine, and desipramine) and antibiotics (clindamycin, trimethoprim, and roxithromycin) all of which inhibit the respiratory burst, to investigate the role of the phospholipase D/PAH pathway in neutrophil activation. The phosphatidylcholine (PC) pool in intact cells was first labeled using [3H]-1-O-alkyl-lysoPC; released [3H]-PA and [3H]-DG were then quantified after the addition of either chemo-attractant or PMA. Using either agonist, all compounds showed a dose-dependent inhibition of [3H]-DG generation which correlated with inhibition of O2- generation, but compounds failed to inhibit directly the NADPH oxidase in a cell-free system. For either activator, a plot of the ID50 values for O2- generation vs those for DG generation was linear over four orders of magnitude. In many cases, inhibition of [3H]-DG generation corresponded to an increase in [3H]-PA, implicating PAH as the locus of inhibition. Superoxide generation was inhibited under conditions where PA was either elevated or minimally affected. Neither O2- release nor DG generation showed any selectivity for stereoisomers of propranolol, suggesting that this inhibition does not act via a specific binding site on PAH. No evidence was obtained for an effect of the inhibitors on PA mobility as monitored by electron spin resonance studies of spin-labeled PA in a model membrane system. Data are consistent with an effect of the inhibitors at the level of the interaction of PAH with the membrane and/or its substrate. These data imply that DG produced via the phospholipase D/PAH pathway functions in the activation or maintenance of the respiratory burst.
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PMID:Role of phospholipase D-derived diradylglycerol in the activation of the human neutrophil respiratory burst oxidase. Inhibition by phosphatidic acid phosphohydrolase inhibitors. 132 85

Microorganisms which are taken up by professional phagocytic cells of a host organism (e.g., by macrophages and polymorphonuclear leukocytes) encounter a series of antimicrobial events including confrontation with toxic oxygen species, derived mainly from the superoxide radical produced by phagocytic NADPH oxidase after uptake of the microorganism. Many microbes are susceptible to the oxygen-dependent phagocytic stress and are efficiently killed. The strategies of some microorganisms to bypass an encounter with the phagocytes' reactive oxygen species, and biochemical systems contributing to the microbes' resistance to killing by reactive oxygen species are outlined.
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PMID:Microbial strategies to prevent oxygen-dependent killing by phagocytes. 160 28

A putative reservoir of functional plasma membrane proteins, the secretory vesicle identified by latent alkaline phosphatase and tetranectin, has previously been demonstrated based on indirect evidence (Borregaard, N., Miller, L. J., and Springer, T. A. (1987) Science 237, 1204-1206; Borregaard, N., Christensen, L., Bjerrum, O. W., Birgens, H. S., and Clemmesen, I. (1990) J. Clin. Invest. 85, 408-416). Difficulties in separating plasma membranes from this entity by density gradient centrifugation has prohibited discriminative dynamic and quantitative studies of secretory vesicles and plasma membranes. By combining density centrifugation with free flow electrophoresis we overcame this obstacle. Freshly prepared unperturbed human neutrophils were subjected to nitrogen cavitation followed by density centrifugation on Percoll gradients. Light membrane fractions containing plasma membranes and secretory vesicles were applied to high voltage free flow electrophoresis on an Elphor VaP 22. Plasma membrane vesicles, identified by HLA class I antigen mixed enzyme-linked immunosorbent assay (Bjerrum, O. W., and Borregaard, N. (1990) Scand. J. Immunol. 31, 305-313) and 125I applied to cells before cavitation, were clearly separated from secretory vesicles. Electron microscopy revealed a morphology typical of plasma membranes in the former fraction and a population of vesicles with markedly different appearance in the latter. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis profiles demonstrated distinct differences in protein patterns between the two fractions. Superoxide generating capacity induced by sodium dodecyl sulfate and cytosol, an entity traditionally ascribed to the plasma membrane, was largely confined to fractions containing secretory vesicles. Thus, the majority of membrane-bound NADPH oxidase components of light membranes of human neutrophils colocalize with secretory vesicles.
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PMID:Separation of human neutrophil plasma membrane from intracellular vesicles containing alkaline phosphatase and NADPH oxidase activity by free flow electrophoresis. 163 31

Superoxide generation in the NADPH oxidase reaction of NADPH-cytochrome P-450 reductase, demonstrated using the ESR spin trap, 5,5-dimethyl-1-pyrroline-1-oxide, increased on the addition of lactoferrin. The NADPH-lactoferrin reductase activity was assessed in terms of NADPH oxidation and oxygen consumption. From Lineweaver-Burk plots, the Km and Vmax for lactoferrin were estimated to be 13 microM and 0.5 S-1, respectively. The liberation of iron from lactoferrin was proven with the use of bathophenanthroline and by the demonstration of bleomycin-dependent DNA degradation; lactoferrin was reduced by the enzyme in the presence of NADPH. During the reaction, the ESR spectrum of the spin trap adduct changed from one characteristic of DMPO-OOH to that of DMPO-OH. The conversion was ascribed to the reaction of hydrogen peroxide with reduced lactoferrin.
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PMID:Lactoferrin-mediated formation of oxygen radicals by NADPH-cytochrome P-450 reductase system. 169 25

Inflammatory response has been assessed in riboflavin or pyridoxine deficient rats. Edema was increased by 54% in pyridoxine deficiency as compared to weight-matched control rats. Food restriction per se reduced the volume of edema by 63%. In pyridoxine deficiency, concentrations of thiobarbituric acid reactive substances (which indicate the extent of lipid peroxidation) increase by 30 and 43% respectively in the edematous tissues of the paw as well as in the wounded skin. Both these parameters were not affected by riboflavin deficiency. Activities of NADPH oxidase and superoxide dismutase in elicited leukocytes from peritoneal cavity were reduced by 54 and 52%, respectively, in riboflavin deficiency but were unaltered in pyridoxine deficiency. Superoxide level and acid phosphatase activity were not influenced by either of the deficiencies, whereas hydrogen peroxide level was increased by 48% in riboflavin deficiency. Food restriction did not affect leukocyte enzymes or the levels of reduced oxygen species. The data suggest that inflammation is enhanced in pyridoxine deficiency but not in riboflavin deficiency.
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PMID:Effect of riboflavin or pyridoxine deficiency on inflammatory response. 181 86

Human fibroblasts have the capacity to release superoxide radicals upon stimulation of an electron transport system similar to the NADPH oxidase of leukocytes. Two components of the NADPH oxidase system, (1) a flavoprotein of 45 kDa which binds diphenylene iodonium (a compound described as a specific inhibitor of the leukocyte NADPH oxidase), and (2) a low-potential cytochrome b, are present in fibroblast membranes. Fibroblasts exhibit these compounds at lower concentrations than do polymorphonuclear leukocytes or B-lymphocytes. The superoxide-generating system is rather uniformly associated with the outer cell membrane, as shown by light and electron microscopy. Superoxide release upon stimulation with various agents was prevented by the addition of micromolar concentrations of diphenylene iodonium, making an NADPH oxidase a likely source.
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PMID:Identification of a superoxide-generating NADPH oxidase system in human fibroblasts. 185 Feb 40

Superoxide production by phagocytic blood cells involves assembly of an active NADPH oxidase complex from components found both in membrane and cytosolic locations in resting cells. We recently cloned cDNAs encoding two cytosolic components (p47-phox and p67-phox) of the oxidase that are deficient in distinct forms of autosomal recessive chronic granulomatous disease. The precise roles of p47-phox and p67-phox were explored further using purified factors produced in large quantities using recombinant baculoviruses to infect cultured Sf9 insect cells. Neither p47-phox nor p67-phox are thought to represent the flavoprotein components of the oxidase, since neither of the purified recombinant factors contained or bound FAD. Recombinant p47-phox and p67-phox are capable of restoring the deficient cytosol from chronic granulomatous disease patient neutrophils to nearly normal levels in a cell-free reconstitution system. Both p47-phox and p67-phox, used together in the absence of neutrophil cytosol, are incapable of supporting cell free production of superoxide, confirming the involvement of other soluble factor(s) in the assembly of an active oxidase in vitro.
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PMID:Characterization of neutrophil NADPH oxidase factors p47-phox and p67-phox from recombinant baculoviruses. 191 85

The effects of lidocaine, a local anesthetic, on various stimulation-coupled responses of neutrophils were studied. Superoxide generation, generation of chemiluminescence, depolarization of membrane potential and transitional increase in intracellular Ca2+ were inhibited by lidocaine in a concentration dependent manner. Lidocaine also inhibited Ca(2+)-activated phospholipid-dependent protein kinase (PKC) in the presence of various concentrations of Ca2+, phosphatidylserine and dioleoylglycerol. For the inhibition of all these stimulation-coupled responses, a similar order of the lidocaine concentration was needed. As in the case of dibucaine (Mori, T., Takai, Y., Minakuchi, R., Yu, B. and Nishizuka, Y., J. Biol. Chem. 255:8378-8380, 1980), lidocaine inhibited PKC activity in a manner competitive with phosphatidylserine. Lidocaine also inhibited the phosphorylation of 47 kDa neutrophil cytosplasmic protein, a phosphorylated protein required for NADPH oxidase activation. Thus, the cellular membrane phospholipid may be one of the target sites of lidocaine for the inhibitory action on the various stimulation-coupled responses of neutrophils, and these effects of lidocaine may correlate with its inhibitory action on PKC activity.
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PMID:Lidocaine inhibits stimulation-coupled responses of neutrophils and protein kinase C activity. 196 97

Superoxide production by neutrophil NADPH oxidase activated in a cell-free system consisting of plasma membranes, cytosol and arachidonate is enhanced by nonhydrolyzable analogs of GTP and reduced by GDP. To characterize the interaction of guanine nucleotides with the system, dialdehyde analogs of GTP and GDP (oGTP and oGDP) were employed. oGDP or oGTP caused an irreversible and dose dependent inactivation of NADPH oxidase-supporting cytosolic activity. Cytosol was fractionated on S and Q Sepharose ion exchange columns into three fractions, combinations of which synergistically supported activation of NADPH oxidase. Two fractions shown by immunoblotting to contain the oxidase-linked p47 and p67 proteins were inactivated by oGDP. Labeling with [alpha-32P]-oGTP lead to incorporation of the label into several proteins.
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PMID:Dialdehyde-GDP blocks activity of cytosolic components of neutrophil NADPH oxidase. 204 36

IgG1 is cleaved in vitro by granulocyte elastase into Fc, Fab and Fabc fragments. The cleaved products have been isolated by a series of chromatographic procedures and characterized with regard to molecular mass and isoelectric point. The Fc fragment has been previously shown to express at its N-terminal site a neoantigen which is specific for elastase (Kolb, G., Eckle, I., Heidtmann, H.-H., Neurath, F. & Havemann, K. (1988) Scand. J. Rheumatol. S75, 179-189). The production of superoxide radical anions in prestimulated neutrophils is inhibited dose-dependently by the elastase-generated Fc and Fabc fragments. Native IgG1 and Fab fragments show no inhibitory effect, nor do papain-generated Fc fragments. The degree of inhibition depends on the stimulus applied: half-maximal inhibition is obtained by 6 microM Fc after stimulation with 4 beta-phorbol and 2.4 microM after stimulation with fMet-Leu-Phe; neutrophils stimulated with serum-activated zymosan are not inhibited by IgG fragments. The effect of Fc is purely cellular; no inhibition of O2 generation can be produced by applying Fc to the xanthine oxidase/xanthine system. The fragments have no effect on the activation or activity of crude NADPH oxidase, which is the O2-forming enzyme system of neutrophils. Possible mechanisms are discussed by which Fc acts on stimulated neutrophils.
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PMID:Inhibition of neutrophil oxidative burst by elastase-generated IgG fragments. 215 63


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