Assembly of phagocyte NADPH oxidase: A concerted binding process?

Karimi, Gilda; Levin, Chantal Houée; Dagher, Marie-Claire; Baciou, Laura; Bizouarn, Tania

doi:10.1016/j.bbagen.2014.07.022

Cited by 30 publications

(34 citation statements)

References 41 publications

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“…We chose to pre-incubate for 10 s because a preincubation for longer time (30 s) led to a drastic decrease of the activity. This was also observed in the case of separated subunits [71].…”

Section: Resultssupporting

confidence: 71%

Cholesterol: A modulator of the phagocyte NADPH oxidase activity - A cell-free study

2014

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The NADPH oxidase Nox2, a multi-subunit enzyme complex comprising membrane and cytosolic proteins, catalyzes a very intense production of superoxide ions O2•−, which are transformed into other reactive oxygen species (ROS). In vitro, it has to be activated by addition of amphiphiles like arachidonic acid (AA). It has been shown that the membrane part of phagocyte NADPH oxidase is present in lipid rafts rich in cholesterol. Cholesterol plays a significant role in the development of cardio-vascular diseases that are always accompanied by oxidative stress. Our aim was to investigate the influence of cholesterol on the activation process of NADPH oxidase. Our results clearly show that, in a cell-free system, cholesterol is not an efficient activator of NADPH oxidase like arachidonic acid (AA), however it triggers a basal low superoxide production at concentrations similar to what found in neutrophile. A higher concentration, if present during the assembly process of the enzyme, has an inhibitory role on the production of O2•−. Added cholesterol acts on both cytosolic and membrane components, leading to imperfect assembly and decreasing the affinity of cytosolic subunits to the membrane ones. Added to the cytosolic proteins, it retains their conformations but still allows some conformational change induced by AA addition, indispensable to activation of NADPH oxidase.

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“…We chose to pre-incubate for 10 s because a preincubation for longer time (30 s) led to a drastic decrease of the activity. This was also observed in the case of separated subunits [71].…”

Section: Resultssupporting

confidence: 71%

Cholesterol: A modulator of the phagocyte NADPH oxidase activity - A cell-free study

2014

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“…This reactive oxygen species and its derivatives mediate many of the microbicidal, tumoricidal, and inflammatory activities of these cells [de Oliveira-Junior et al, 2011]. The catalytic subunit of the phagocyte oxidase enzyme complex is a membrane-spanning flavocytochrome b composed of a 91 kDa glycoprotein, termed gp91- phox , and a 22 kDa non-glycosylated polypeptide, termed p22- phox , encoded respectively by the CYBB and CYBA genes [Karimi et al, 2014; Nauseef and Borregaard, 2014]. Defects in these genes are responsible for the X-linked and one of the autosomal recessive forms of chronic granulomatous disease (CGD), a primary immunodeficiency disorder characterized by severe, recurrent bacterial and fungal infections [Roos and de Boer, 2014].…”

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confidence: 99%

Regulation of CYBB Gene Expression in Human Phagocytes by a Distant Upstream NF‐κB Binding Site

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Zhu

et al. 2015

J of Cellular Biochemistry

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The human CYBB gene encodes the gp91-phox component of the phagocyte oxidase enzyme complex, which is responsible for generating superoxide and other downstream reactive oxygen species essential to microbial killing. In the present study, we have identified by sequence analysis a putative NF-κB binding site in a DNase I hypersensitive site, termed HS-II, located in the distant 5′ flanking region of the CYBB gene. Electrophoretic mobility assays showed binding of the sequence element by recombinant NF-κB protein p50 and by proteins in nuclear extract from the HL-60 myeloid leukemia cell line corresponding to p50 and to p50/p65 heterodimers. Chromatin immunoprecipitation demonstrated NF-κB binding to the site in intact HL-60 cells. Chromosome conformation capture (3C) assays demonstrated physical interaction between the NF-κB binding site and the CYBB promoter region. Inhibition of NF-κB activity by salicylate reduced CYBB expression in peripheral blood neutrophils and differentiated U937 monocytic leukemia cells. U937 cells transfected with a mutant inhibitor of κB “super-repressor” showed markedly diminished CYBB expression. Luciferase reporter analysis of the NF-κB site linked to the CYBB 5′ flanking promoter region revealed enhanced expression, augmented by treatment with interferon-γ. These studies indicate a role for this distant, 15 kb upstream, binding site in NF-κB regulation of the CYBB gene, an essential component of phagocyte-mediated host defense.

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“…Macrophages and neutrophils phagocytose microorganisms to remove them from blood and tissues. As the phagosome matures the multisubunit NADPH oxidase assembles on its membrane and reduces O 2 to generate superoxide in the lumen of the phagosome (Karimi et al, 2014; Nauseef, 2004). The products of this respiratory burst –superoxide and subsequently other reactive oxygen species (ROS)– are bactericidal.…”

Section: Introductionmentioning

confidence: 99%