Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q00604 (X-linked)
 16,883 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Analysis of dithionite difference spectra demonstrated that cytochrome b was present in neutrophil homogenates from a 17-year-old girl and her 25-year-old brother who had the autosomal recessive form of chronic granulomatous disease, and from an 18-year-old boy with the X-linked form of chronic granulomatous disease. These results indicate that the postulated importance of cytochrome b in the oxygen burst during phagocytosis is questionable.
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PMID:Cytochrome b is present in neutrophils from patients with chronic granulomatous disease. 8 17

Recombinant interferon-gamma (rIFN-gamma) therapy has become an effective form of prophylaxis for patients with chronic granulomatous disease (CGD). Preliminary studies with CGD suggested that rIFN-gamma treatment enhanced phagocyte oxidase activity and increased superoxide (O2-) production. We evaluated several aspects of neutrophil NADPH oxidase activity in 19 CGD patients (representing all four known types of CGD) receiving prolonged rIFN-gamma therapy (6 to 27 months). In contrast to earlier studies, we failed to detect any improvement in neutrophil NADPH oxidase activity in 18 of the 19 CGD patients as determined by (1) intact cell O2- production (continuous assay), (2) nitroblue tetrazolium (NBT) staining, (3) cytochrome b558 spectroscopy, and (4) activity levels of cytosol and membrane oxidase components using a cell-free activation system. One patient with a variant form of X-linked CGD had a transient increase in neutrophil O2- production following 3 months of rIFN-gamma therapy. However, this was not sustained, and was not associated with any change in cytochrome b levels. In some patients, rIFN-gamma therapy was associated with the appearance of a small subset of circulating monocytes (1% to 20%) that were NBT-positive. Although the functional significance of this monocyte subpopulation needs to be determined, these results suggest that one possible mechanism by which rIFN-gamma may benefit CGD patients is by partially correcting the respiratory burst defect in a subset of monocytes. We conclude that the clinical benefit of prolonged rIFN-gamma therapy in the vast majority of CGD patients is not due to enhanced neutrophil NADPH oxidase activity. The mechanism of action of rIFN-gamma in most CGD patients remains unknown.
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PMID:Prolonged recombinant interferon-gamma therapy in chronic granulomatous disease: evidence against enhanced neutrophil oxidase activity. 131 72

Neutrophil plasma membranes from patients with the X-linked and autosomal recessive forms of chronic granulomatous disease (CGD) that lack cytochrome b are incapable of generating superoxide anion (O2-) in vivo and in vitro. The O2- generating activity of these defective membranes was reconstituted with the addition of partially purified human neutrophil cytochrome b in a detergent-based, cell-free activation system. Depending on the detergent system used, 50% to 100% of the activity of control membranes was recovered, and this activity was directly dependent on the cytochrome b concentration. However, when cytochrome b was purified to 99% homogeneity, the reconstitutive capacity of the cytochrome was lost, possibly because of subtle denaturation of the cytochrome or the removal of an additional required cofactor. Examination of the latter possibility with respect to a protein known to coassociate with the cytochrome, ie, Rap1A, indicated that this ras-like protein was present in the partially purified cytochrome preparation used to reconstitute activity in CGD membranes, but was missing in the highly purified preparation. However, the finding that Rap1A was present in normal amounts in the neutrophil membranes from all four major types of CGD (including those missing cytochrome b) suggested that the conditions required of the reconstitution assay did not favor the reassociation of the membrane-derived Rap1A with exogenously added cytochrome b or that another unidentified membrane component was lost during the final purification step. The normal expression of Rap1A in CGD cell membranes also indicates that this protein is not responsible for the absence of O2- production in the X-linked and autosomal recessive cytochrome b-negative forms of CGD. Finally, these results show that the expression of Rap1A in the plasma membrane is not dependent on the coordinate expression of cytochrome b, despite the close association shown for these two proteins in the normal cell membrane.
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PMID:Reconstitution of defective respiratory burst activity with partially purified human neutrophil cytochrome B in two genetic forms of chronic granulomatous disease: possible role of Rap1A. 131 74

The NADPH oxidase of phagocytic cells is important for the efficient killing and digestion of ingested microbes. A very unusual low-potential cytochrome b (b-245) is the only redox molecule to have been identified in this system. The FAD-containing flavoprotein that binds NADPH and transfers electrons to the cytochrome has eluded identification for three decades. We show here that the haem/FAD ratio in the membranes does not change significantly on activation of this oxidase, indicating that the FAD is present in the membranes from the outset and not recruited from the cytosol. The FAD content of membranes from cells of patients with X-linked chronic granulomatous disease (CGD) lacking the cytochrome b was roughly one-quarter of that in normal subjects and in autosomal recessive CGD patients lacking the cytosolic protein p47-phox. Similar low amounts of FAD were present in uninduced promyelocytic (HL60) cells, suggesting that the low amount of FAD in cells from X-CGD patients was probably unrelated to this oxidase system. Cytochrome b-245 appears to bind both the haem and FAD, in a molar ratio of 2:1. The e.p.r. signal of the purified cytochrome was weak and had an asymmetric g(z) peak at g = 3.31. The purified cytochrome could be partially reflavinated (about 20%) in the presence of lipid. Amino acid sequence homology was detected between the beta-subunit of this cytochrome b and the ferredoxin-NADP+ reductase (FNR) family of reductases in the putative NADPH- and FAD-binding sites. 32P-labelled 2-azido-NADP was used as a photoaffinity label for the NADPH-binding site. Labelling that was competed off with NADP was observed in the region of the beta-subunit of the cytochrome. No labelling was seen in this region in X-CGD in three subjects in whom this cytochrome was missing and in a third in whom it was present but bore a Pro-His transposition in the putative NADPH-binding site. These studies indicate that cytochrome b-245 is a flavocytochrome, the first described in higher eukaryotic cells, bearing the complete electron-transporting apparatus of the NADPH oxidase.
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PMID:Cytochrome b-245 is a flavocytochrome containing FAD and the NADPH-binding site of the microbicidal oxidase of phagocytes. 132 Mar 78

The polymorphonuclear (PMN) cells from a patient with cytochrome b positive X-linked chronic granulomatous disease (Xb+ CGD) were studied using flow cytometry. Both the cell surface expression of monoclonal antibody defined cytochrome b and the superoxide production (intracellular 2',7'-Dichlorofluorescin Diacetate oxidation) were investigated at a single cell level. Flow cytometry clearly demonstrated the complete absence of superoxide production in the patient's PMN cells, the mosaicism in his mother's PMN cells and also indicated the normal cell surface expression of cytochrome b. The results obtained by Western blot analysis and reduced-minus-oxidized spectra confirmed the presence of functional and normal amounts of cytochrome b. We concluded that this is a case of Xb+ CGD with a normal cell surface expression of cytochrome b.
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PMID:Cytochrome b positive X-linked chronic granulomatous disease: a normal cell surface expression of cytochrome b. 132 64

We have compared assays for products of the neutrophil respiratory burst in normal EBV-transformed B cell lines stimulated with agonists of protein kinase C. Those measuring O2- directly or its immediate product, H2O2, were successful. Of these, the most sensitive were the lucigenin- and luminol-based chemiluminescence assays for O2- and H2O2 respectively. Cell lines from CGD patients, with X-linked or autosomal recessive genetic defects in the neutrophil NADPH oxidase, did not respond in these assays, indicative of their inability to produce O2-. The defects in the lines studied encompass both proteins forming the cytochrome b-245 membrane component, and the 47 kDa cytosolic component of the NADPH oxidase. The possession of the disease associated phenotype by these cell lines provides evidence that in the normal situation both neutrophils and B cells produce O2- via the same system.
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PMID:Superoxide production by normal and chronic granulomatous disease (CGD) patient-derived EBV-transformed B cell lines measured by chemiluminescence-based assays. 133 Dec 41

Genetic heterogeneity in 12 patients from 11 different families with X-linked recessive chronic granulomatous disease was studied by Southern blot analysis using cytochrome b heavy-chain cDNA as a probe. We found the abnormal restriction length fragment patterns of the cytochrome b heavy-chain gene in three families, which were not observed in healthy controls. DNA from one patient showed the abnormal patterns after digestion with several restriction enzymes. The DNA of two other patients showed the abnormality only with TaqI and PstI. Analysis of the same family members indicated that these abnormal patterns cosegregated with the disease. The other nine patients from eight families did not have any abnormalities detectable by Southern blot analysis. Although further experimentation should be done to study the molecular genetic heterogeneity in most X-linked chronic granulomatous disease families (eight of 11), we were able to demonstrate at least three different types of mutations in the cytochrome b heavy-chain gene responsible for the disease.
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PMID:Genetic heterogeneity in patients with X-linked recessive chronic granulomatous disease. 160 31

Chronic Granulomatous Disease (CGD) manifests as a predisposition to infection as a result of defective function of the NADPH oxidase of phagocytic cells. Proteins identified as part of this system include two subunits of a cytochrome b (cytochrome b-245) and two cytosolic factors. The affected oxidase component was determined in 63 CGD patients from 57 families, by Western blotting of extracts of their neutrophils with antibodies to those proteins. 38 (67%) of the families were X-linked with a defect of the beta subunit of the cytochrome. 13 (23%) lacked p47-phox, 3 (5%) p67-phox, and 3 (5%) the alpha subunit of the cytochrome.
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PMID:Identification of the defective NADPH-oxidase component in chronic granulomatous disease: a study of 57 European families. 163 35

Variant X-linked chronic granulomatous disease (CGD) is characterised by a decreased but still measurable respiratory burst and cytochrome b content of phagocytes resulting in a clinically milder form of the disease. We examined the in vivo effect of recombinant human granulocyte-macrophage colony stimulating factor (rh-GM-CSF) on the neutrophil functions of a patient treated for liver abscess. The number of white blood cells was markedly increased at the highest dose of GM-CSF injected (30 micrograms/kg per day). This was mainly due to a large increase in eosinophils and to a lesser extent in neutrophils. No change in the deficient neutrophil respiratory burst nitroblue tetrazolium (NBT)-reduction, superoxide (O2-)-production and cytochrome b content was observed during 6 weeks of therapy with increasing doses of GM-CSF. No significant clinical improvement of the liver abscess was observed during treatment with GM-CSF.
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PMID:Granulocyte-macrophage colony stimulating factor does not improve neutrophil oxidative metabolism in a patient with variant X-linked chronic granulomatous disease. 165 35

The bactericidal activity of phagocytic cells depends largely on the production of highly reactive metabolites from the metabolism of oxygen. A lesion anywhere in the biochemical pathway of hydrogen peroxide production has the potential to cause chronic granulomatous disease (CGD). Recent findings have shown that CGD results from distinct abnormalities in the NADPH oxidase system, which includes the membrane-associated proteins, NADPH oxidase, cytochrome b-558, and several cytosolic proteins. Specific genetic markers have been identified for the most common biochemical variants of CGD. Pharmacologic alteration of phagocyte oxidative metabolism is now possible through the use of recombinant interferon-gamma. In vitro studies have shown that neutrophils and monocytes derived from patients with autosomal recessive cytochrome b-positive CGD respond to interferon-gamma with an enhanced respiratory burst (superoxide production) and increased bactericidal activity. Furthermore, subcutaneous interferon-gamma administration improves bactericidal activity in neutrophils and monocytes derived from patients with X-linked, cytochrome b-negative CGD, despite the lack of effect on superoxide production. This suggests that interferon-gamma also stimulates nonoxidative bactericidal pathways. Data from a multicenter clinical trial indicate sustained administration of interferon-gamma is effective in the management of CGD. In addition, related studies indicate that modern molecular and genetic technologies offer the possibility of improved management or cure for CGD.
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PMID:Interferon-gamma in the treatment of the chronic granulomatous diseases of childhood. 193 7


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