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)

Reactive oxygen species contribute to glomerular damage and proteinuria. In this study, we show that cultured human podocytes produce superoxide in response to extracellular adenosine triphosphate (ATP), and we identified the oxidases involved in this process. Adenosine triphosphate (10-4 M for 4 hr) raised superoxide production from 1.28 +/- 0.15 to 2.67 &/- 0.34 nmol/mg protein/min. Studies with podocyte homogenates revealed activation of both nicotinamide adenine dinucleotide (NADH; from 2.65 +/- 0.23 to 7.43 +/- 0.57) and nicotinamide adenine dinucleotide phosphate (NADPH) dependent oxidases [from 1.74 +/- 0.13 to 4.05 +/- 0.12 (nmol O2/mg protein/min)] by ATP. Activity of xanthine-oxidases was low and unchanged by ATP. Activation of the plasma-membrane bound NAD(P)H oxidases by ATP was time and dose dependent. Reverse transcribed-polymerase chain reaction (RT-PCR) studies with primers derived from monocyte sequences amplified mRNA for the NADPH oxidase subunits p22phox, p47phox, gp91phox, and p67phox, and the latter was transiently increased by ATP. Experiments with actinomycin D and cycloheximide suggested that ATP modulates enzyme activity at the transcriptional and translational levels. In conclusion, NAD(P)H dependent, membrane associated oxidases represent the major superoxide source in human podocytes. Activation of NAD(P)H oxidase by ATP might be secondary to increased mRNA expression of the NADPH oxidase subunit gp67phox.
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PMID:NAD(P)H oxidase activity in cultured human podocytes: effects of adenosine triphosphate. 950 11

Respiratory burst activity of murine microglial cells was investigated in vitro under normoxic and hypoxic conditions with a chemoluminometric assay. Hypoxia for 24 hours reduced the release of extracellular reactive oxygen intermediates (ROIs), whereas reoxygenation increased the chemoluminescence more than sevenfold. Blockade of potassium channels inhibited the increase of oxidative burst after reoxygenation, indicating that potassium ions, which were increased in the supernatant of hypoxic microglial cells, were involved in this activation process. Also, blockade of voltage-gated calcium channels with nifedipine attenuated the increased release of ROIs. With fura-2 analysis, it was shown that the activation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase by potassium ions was mediated by calcium influx via voltage-gated calcium channels. Thus, influx of calcium ions through voltage-gated channels activates the NADPH oxidase in microglial cells during reoxygenation. By the increased production of ROIs, microglial cells may add to the reperfusion injury after ischemia in vivo.
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PMID:Reoxygenation increases the release of reactive oxygen intermediates in murine microglia. 962 91

Chronic granulomatous disease (CGD) is a disorder of the lymphohematopoietic system, whereby phagocytes of affected patients are unable to kill microorganisms. CGD is caused by a functional defect in the phagocytic nicotinamide adenine dinucleotide phosphatase (NADPH) oxidase (phox) enzyme complex, leading to a lack of microbicidal metabolites. As a therapeutic approach toward the predominant X-linked form of CGD, we have developed a bicistronic retroviral vector containing the coding sequences of gp91-phox and a cytoplasmically truncated version of the human low-affinity receptor for nerve growth factor (deltaLNGFR). Full reconstitution of superoxide-generating activity was achieved with this vector in a gp91-phox-deficient cell line. Using an optimized gene transfer protocol, up to 85% of the CD34+ cells obtained from the bone marrow of X-CGD patients were transduced. CD15+ cells differentiated in vitro from transduced X-CGD CD34+ cells showed correction of NADPH oxidase activity to 45-52% of normal levels whereas deltaLNGFR expression was found in 40-67% of the CD15+ cells. Moreover, immunoblots prepared from extracts of transduced CD15+ cells revealed gp91-phox protein levels similar to those found in neutrophils derived from normal CD34+ cells. Taking into consideration that superoxide production in only 5 to 10% of wild-type neutrophils is sufficient to protect X-CGD heterozygotes from serious infections, the results achieved in this study shows that for X-CGD patients a curative approach based on the genetic modification of hematopoietic stem/progenitor cells is feasible.
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PMID:Correction of respiratory burst activity in X-linked chronic granulomatous cells to therapeutically relevant levels after gene transfer into bone marrow CD34+ cells. 969 55

Osteoclasts use a variety of chemical agents to degrade bone. One important component of this process is the generation of superoxide. It has been reported that nicotinamide adenine dinucleotide phosphate (NADPH) oxidase is the enzyme responsible for superoxide production in phagocyte; however, the NADPH oxidase present in osteoclasts has not been studied in detail. One of the membrane-bound subunits of the NADPH oxidase is gp91(phox) which represents the rate-limiting component for the formation of the NADPH oxidase complex. This study was designed to demonstrate the presence of gp91(phox) in individual osteoclasts using the RT-PCR technique developed for limited numbers of cells. Compared with white cells, 1.8 times the amount of gp91(phox) mRNA was found in osteoclasts. This difference may be related to the size of the osteoclast and the multiple nuclei present. The presence of gp91(phox) in osteoclasts was confirmed at protein level by immunocytochemistry. Osteoclastic superoxide generation is inhibited by diphenylene iodonium, a specific inhibitor of the NADPH oxidase. These studies suggest that superoxide generation by osteoclasts correlates with the activity of NADPH oxidase.
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PMID:Nicotinamide adenine dinucleotide phosphate oxidase in the formation of superoxide in osteoclasts. 974 95

Human neutrophils have a short half-life and are believed to die by apoptosis or programmed cell death both in vivo and in vitro. We found that caspases are activated in a time-dependent manner in neutrophils undergoing spontaneous apoptosis, concomitant with other characteristic features of apoptotic cell death such as morphologic changes, phosphatidylserine (PS) exposure, and DNA fragmentation. The treatment of neutrophils with agonistic anti-Fas monoclonal antibodies (MoAbs) significantly accelerated this process. However, in cells treated with the potent neutrophil activator phorbol 12-myristate 13-acetate (PMA), caspase activity was only evident after pharmacologic inhibition of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. Similarily, inhibition of the NADPH oxidase in constitutive and Fas/APO-1-triggered apoptosis resulted in increased rather than suppressed levels of caspase activity, suggesting that reactive oxygen species may prevent caspases from functioning optimally in these cells. Moreover, oxidants generated via the NADPH oxidase were essential for PS exposure during PMA-induced cell death, but not for neutrophils undergoing spontaneous apoptosis. We conclude that caspases are an important component of constitutive and Fas/APO-1-triggered neutrophil apoptosis. However, these redox sensitive enzymes are suppressed in activated neutrophils, and an alternate oxidant-dependent pathway is used to mediate PS exposure and neutrophil clearance under these conditions.
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PMID:Involvement of caspases in neutrophil apoptosis: regulation by reactive oxygen species. 984 48

A membrane-bound cytochrome b558, a heterodimer consisting of gp91-phox and p22-phox, is a critical component of the superoxide (O2-)-generating reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase in phagocytes. Chronic granulomatous disease (CGD) is characterized by recurrent bacterial infection caused by a defect of the oxidase. Both subunits are absent from phagocytes in typical X-linked recessive CGD patients who are primarily defective in gp91-phox. We report here an atypical case of X-linked CGD in which neutrophils showed a complete absence of O2--forming NADPH oxidase activity, but a small amount (about 10% of control) of both subunits was detected by immunoblot analysis. Spectrophotometric studies of the neutrophils with a recently developed sensitive method gave no evidence for the heme spectrum in the cytochrome b558, of this CGD. Reverse transcription/polymerase chain reaction and sequence analysis revealed a C to T transition replacing histidine at amino acid position 101 (His101) by tyrosine in gp91-phox. These results provide evidence that His101 of gp91-phox is the one of the heme-binding ligands of cytochrome b558.
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PMID:A novel mutation at a probable heme-binding ligand in neutrophil cytochrome b558 in atypical X-linked chronic granulomatous disease. 985 76

Optimal microbicidal activity of polymorphonuclear leukocytes (PMNs) requires recruitment of a functional nicotinamide adenine dinucleotide phosphate (NADPH) oxidase to the phagosome. In this study, we used a synchronized phagocytosis assay and immunofluorescence microscopy (IFM) to examine the association of cytosolic NADPH oxidase subunits with phagosomes containing opsonized zymosan (OpZ). Ingestion of OpZ began within 30 seconds of particle binding and forming phagosomes were enriched for both F-actin and the actin-binding protein p57. NADPH oxidase subunits p47phox and p67phox were also recruited to forming phagosomes and were retained on mature phagosomes for at least 15 minutes. Colocalization of F-actin, p57, and p47phox on phagosomes was confirmed by immunoblotting. Translocation of p67phox, but not p57, to forming phagosomes was deficient in PMNs lacking p47phox. Surprisingly, we found that in PMNs from six individuals with X-linked chronic granulomatous disease (CGD), p47phox and p67phox accumulated in the periphagosomal area during ingestion of OpZ. However, in marked contrast to normal PMNs, p47phox and p67phox were shed from nascent phagosomes along with F-actin and p57 once OpZ was internalized (approximately 5 minutes). These data support a model in which flavocytochrome b is required for stable membrane binding of p47phox and p67phox, but not their association with the cytoskeleton or transport to the cell periphery.
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PMID:Transient association of the nicotinamide adenine dinucleotide phosphate oxidase subunits p47phox and p67phox with phagosomes in neutrophils from patients with X-linked chronic granulomatous disease. 1023 5

Chronic granulomatous disease (CGD) is an inherited deficiency of the superoxide-generating phagocyte nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, resulting in recurrent, severe bacterial and fungal infections. The X-linked form of this disorder (X-CGD) results from mutations in the X-linked gene for gp91(phox), the larger subunit of the oxidase flavocytochrome b(558). In this study, we used a murine model of X-CGD to examine the long-term function of retroviral vectors for expression of gp91(phox) based on the murine stem cell virus (MSCV) backbone. NADPH oxidase activity was reconstituted in neutrophils and macrophages for up to 18 to 24 months posttransplantation of transduced X-CGD bone marrow into lethally irradiated syngeneic X-CGD mice. Southern blot analysis and secondary transplant data showed proviral integration in multilineage repopulating cells. Although relatively small amounts of recombinant gp91(phox) (approximately 5% to 10% of wild-type levels) were detected in neutrophils after retroviral-mediated gene transfer, superoxide-generating activity was approximately 20% to 25% of wild-type mouse neutrophils. Expression of gp91(phox) is normally restricted to mature phagocytes. No obvious toxicity was observed in other hematopoietic lineages in transplant recipients, and provirus-marked cells were capable of reconstituting secondary transplant recipients, who also exhibited NADPH oxidase-positive neutrophils. MSCV-based vectors for long-term expression of gp91(phox) may be useful for gene therapy of human CGD targeted at hematopoietic stem cells.
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PMID:Long-term correction of phagocyte NADPH oxidase activity by retroviral-mediated gene transfer in murine X-linked chronic granulomatous disease. 1041 82

Chronic granulomatous disease (CGD) is a rare inherited disorder of phagocytes in which defective production of microbicidal oxidants leads to severe recurrent infections. CGD is caused by mutations in any of 4 genes encoding components of nicotinamide adenine dinucleotide phosphate (reduced form; NADPH) oxidase, the multisubunit enzyme that produces the precursor of these oxidants, superoxide. Approximately 5% of CGD patients have an autosomal recessive form of disease caused by a severe deficiency of p67-phox, a 526-amino acid subunit of the oxidase that appears to regulate electron transport within the enzyme. Here we report the biochemical and molecular characterization of 6 unrelated kindreds with p67-phox deficiency. These studies show that, as in gp91-phox and p22-phox deficiencies, the p67-phox CGD patients show a high degree of heterogeneity in the genetic defects that underlie their disease. Five different mutant alleles were identified: (1) a nonsense mutation in exon 4 (C(304) --> T); (2) a 5-nucleotide (nt) deletion in exon 13 (nts 1169-1173); (3) a splice mutation in the first nucleotide of intron 4 (G --> A); (4) a deletion of 1 nt in exon 9 (A(728)); and (5) a 9-nt in-frame deletion in exon 2 (nts 55-63). The splice mutation was seen in 3 unrelated kindreds, while the 5-nt deletion was seen in 2 apparently unrelated families (both of Palestinian origin). Homozygosity was present in 4 of the kindreds, 2 of which had consanguineous parentage. In the isolated neutrophils of each of the affected patients in the 6 kindreds, there was no measurable respiratory burst activity and no p67-phox protein detected by immunoblot analysis. The level of 67-phox mRNA was less than 10% of normal in the mononuclear leukocytes from 3 of the 4 patients analyzed by Northern blot studies. Thus, this heterogeneous group of mutations in p67-phox all lead to marked instability of mRNA or protein (or both) that results in the complete loss of NADPH oxidase activity.
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PMID:Molecular characterization of autosomal recessive chronic granulomatous disease caused by a defect of the nicotinamide adenine dinucleotide phosphate (reduced form) oxidase component p67-phox. 1049 24

The nicotinamide adenine dinucleotide phosphate (NADPH) binding site of the NADPH oxidase complex is believed to be located on the beta, subunit of cytochrome b558. However, our previous studies showed that p67PHOX also contains an NADPH binding site that is essential for normal oxidase activity and that p67PHOX is able to mediate a slow electron transfer from a reduced pyridine nucleotide to an artificial electron acceptor. Using both affinity labeling and fluorescence quenching, we have obtained further evidence that p67PHOX is able to bind NADPH. We have used a number of truncated forms of p67PHOX, including p67PHOX(1-243), p67PHOX(1-210), p67PHOX(1-199), and p67PHOX(244-526) (where the numbers represent the initial and final amino acids in the truncated p67PHOX) in order to localize the binding site. We found that NADPH could bind to p67PHOX(1-243), p67PHOX(1-210), and p67PHOX(1-199) but not to p67PHOX(244-526). The p67PHOX(1-199) fragment consists largely of four tetratricopeptide (TPR) domains. We showed further that Rac2-GTP gamma S and to a lesser extent Rac2-GDP beta S could modulate the binding of NADPH to p67PHOX.
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PMID:Binding of nicotinamide adenine dinucleotide phosphate to the tetratricopeptide repeat domains at the N-terminus of p67PHOX, a subunit of the leukocyte nicotinamide adenine dinucleotide phosphate oxidase. 1071 28


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