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)

Nox activator 1 (NoxA1) is a homologue of p67(phox) that acts in conjunction with Nox organizer 1 (NoxO1) to regulate reactive oxygen species (ROS) production by the NADPH oxidase Nox1. The phosphorylation of cytosolic regulatory components by multiple kinases plays important roles in assembly and activity of the phagocyte NADPH oxidase (Nox2) system, but little is known about regulation by phosphorylation in the Nox1 system. Here we identify Ser(172) and Ser(461) of NoxA1 as phosphorylation sites for protein kinase A (PKA). A consequence of this phosphorylation was the enhancement of NoxA1 complex formation with 14-3-3 proteins. Using both a transfected human embryonic kidney 293 cell Nox1 model system and endogenous Nox1 in colon cell lines, we showed that the elevation of cAMP inhibits, whereas the inhibition of PKA enhances, Nox1-dependent ROS production through effects on NoxA1. Inhibition of Nox1 activity was intensified by the availability of 14-3-3zeta protein, and this regulatory interaction was dependent on PKA-phosphorylatable sites at Ser(172) and Ser(461) in NoxA1. We showed that phosphorylation and 14-3-3 binding induce the dissociation of NoxA1 from the Nox1 complex at the plasma membrane, suggesting a mechanism for the inhibitory effect on Nox1 activity. Our data establish that PKA-phosphorylated NoxA1 is a new binding partner of 14-3-3 protein(s) and that this forms the basis of a novel mechanism regulating the formation of ROS by Nox1 and, potentially, other NoxA1-regulated Nox family members.
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PMID:Regulation of Nox1 activity via protein kinase A-mediated phosphorylation of NoxA1 and 14-3-3 binding. 1791 9

Activated pancreatic stellate cells (PSCs) play an important role in pancreatic fibrosis and inflammation, where oxidative stress is implicated in the pathogenesis. NADPH oxidase might be a source of reactive oxygen species (ROS) in the injured pancreas. This study aimed to clarify the expression and regulation of cell functions by NADPH oxidase in PSCs. PSCs were isolated from rat and human pancreas tissues. Expression of NADPH oxidase was assessed by reverse transcription-PCR and immunostaining. Intracellular ROS production was assessed using 2',7'-dichlorofluorescin diacetate. The effects of diphenylene iodonium (DPI) and apocynin, inhibitors of NADPH oxidase, on key parameters of PSC activation were evaluated in vitro. In vivo, DPI (at 1 mg.kg body wt(-1).day(-1)) was administered in drinking water to 10-wk-old male Wistar Bonn/Kobori rats for 10 wk and to rats with chronic pancreatitis induced by dibutyltin dichloride (DBTC). PSCs expressed key components of NADPH oxidase (p22(phox), p47(phox), NOX1, gp91(phox)/NOX2, NOX4, and NOX activator 1). PDGF-BB, IL-1beta, and angiotensin II induced ROS production, which was abolished by DPI and apocynin. DPI inhibited PDGF-induced proliferation, IL-1beta-induced chemokine production, and expression of alpha-smooth muscle actin and collagen. DPI inhibited transformation of freshly isolated cells to a myofibroblast-like phenotype. In addition, DPI inhibited the development of pancreatic fibrosis in Wistar Bonn/Kobori rats and in rats with DBTC-induced chronic pancreatitis. In conclusion, PSCs express NADPH oxidase to generate ROS, which mediates key cell functions and activation of PSCs. NADPH oxidase might be a potential target for the treatment of pancreatic fibrosis.
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PMID:NADPH oxidase plays a crucial role in the activation of pancreatic stellate cells. 1796 58

The production of reactive oxygen species (ROS) in mammalian cells is tightly regulated because of their potential to damage macromolecules, including DNA. To investigate possible links between high ROS levels, oxidative DNA damage, and genomic instability in mammalian cells, we established a novel model of chronic oxidative stress by coexpressing the NADPH oxidase human (h) NOX1 gene together with its cofactors NOXO1 and NOXA1. Transfectants of mismatch repair (MMR)-proficient HeLa cells or MMR-defective Msh2(-/-) mouse embryo fibroblasts overexpressing the hNOX1 complex displayed increased intracellular ROS levels. In one HeLa clone in which ROS were particularly elevated, reactive nitrogen species were also increased and nitrated proteins were identified with an anti-3-nitrotyrosine antibody. Overexpression of the hNOX1 complex increased the steady-state levels of DNA 8-oxo-7,8-dihydroguanine and caused a threefold increase in the HPRT mutation rate in HeLa cells. In contrast, additional oxidatively generated damage did not affect the constitutive mutator phenotype of the Msh2(-/-) fibroblasts. Because no significant changes in the expression of several DNA repair enzymes for oxidative DNA damage were identified, we suggest that chronic oxidative stress can saturate the cell's DNA repair capacity and cause significant genomic instability.
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PMID:Overexpression of human NOX1 complex induces genome instability in mammalian cells. 1796 6

The mechanism of angiotensin II (Ang II)-induced superoxide production was investigated with HEK293 or Chinese hamster ovary cells reconstituted with the angiotensin type 1 receptor (AT(1)R) and NADPH oxidase (either Nox1 or Nox2) along with a pair of adaptor subunits (either NOXO1 with NOXA1 or p47(phox) with p67(phox)). Ang II enhanced the activity of both Nox1 and Nox2 supported by either adaptor pair, with more effective activation of Nox1 in the presence of NOXO1 and NOXA1 and of Nox2 in the presence of p47(phox) and p67(phox). Expression of several AT(1)R mutants showed that interaction of the receptor with G proteins but not that with beta-arrestin or with other proteins (Jak2, phospholipase C-gamma1, SH2 domain-containing phosphatase 2) that bind to the COOH-terminal region of AT(1)R, was necessary for Ang II-induced superoxide production. The effects of constitutively active alpha subunits of G proteins and of various pharmacological agents implicated signaling by a pathway comprising AT(1)R, Galpha(q/11), phospholipase C-beta, and protein kinase C as largely, but not exclusively, responsible for Ang II-induced activation of Nox1 and Nox2 in the reconstituted cells. A contribution of Galpha(12/13), phospholipase D, and phosphatidyl-inositol 3-kinase to Ang II-induced superoxide generation was also suggested, whereas Src and the epidermal growth factor receptor did not appear to participate in this effect of Ang II. In reconstituted cells stimulated with Ang II, Nox2 exhibited a more sensitive response than Nox1 to the perturbation of protein kinase C, phosphatidylinositol 3-kinase, or the small GTPase Rac1.
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PMID:Mechanism of angiotensin II-induced superoxide production in cells reconstituted with angiotensin type 1 receptor and the components of NADPH oxidase. 1798 2

Oxidative stress induced by superoxide plays an important role in pathogenesis of cardiovascular diseases. NAD(P)H oxidase is a principal enzymatic origin for superoxide in vasculature. Recently, novel homologues of cytosolic components of NAD(P)H oxidase, Nox organizer 1 (NOXO1) and Nox activator 1 (NOXA1), are identified. On the other hand, oxidized low-density lipoprotein (ox-LDL) generates reactive oxygen species (ROS) in endothelial cells via lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1). In the present investigation, the authors examined the expression, the regulation, and the role of NOXA1 in the generation of ROS in endothelial cells. The expression of NOXA1 was confirmed by reverse transcriptase-polymerase chain reaction (RT-PCR). Dihydroethidium method showed that ox-LDL and angiotensin II increased the generation of intracellular ROS. Once the expression of p22(phox) or NOXA1 was suppressed by siRNA, the generation of ROS induced by ox-LDL and angiotensin II were potently decreased. Moreover, the expression of NOXA1 was increased by ox-LDL in a time-and dose-dependent manner. In conclusion, endothelial NOXA1 plays an essential role in generation of ROS. Ox-LDL not only increased the generation of ROS via LOX-1, but also enhanced the expression of NOXA1 in endothelial cells. NOXA1 is likely a key player that links ox-LDL with the activation of endothelial NAD(P)H oxidase.
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PMID:Essential role of NOXA1 in generation of reactive oxygen species induced by oxidized low-density lipoprotein in human vascular endothelial cells. 1856 54

In pulmonary neuroepithelial bodies (NEB), presumed airway chemoreceptors, classical NADPH oxidase (gp91 phox, NOX2) is co-expressed with O(2) sensitive K(+) channels (K(+)O(2)) and functions as an O(2) sensor. Here we examined related NADPH oxidase homologues "novel oxidases "(NOX 1, 3&4) and their possible involvement in O(2) sensing. For immunolocalization we used specific antibodies against various NADPH components and K(+) (O(2)) subunits to label NEB in rat /rabbit lung and NEB related H146 tumor cell line. For gene expression profiling of NEB cells microdissected from human lung, and H146 cells, we used custom MultiGene-12TM RT-PCR array that included NADPH oxidase components and homologues /accessory proteins (NOX1-4, phox-p22, p40, p47, p67, Rac1, NOXO1 and NOXA1) and K(+)O(2) channels (Kv -1.2, 1.5, 2.1, 3.1, 3.3, 3.4, 4.2, 4.3;TASK1-3). In rat lung, NOX2, NOX4, p22phox, Kv3.3 (and Kv3.4 in rabbit) and TASK1 localized to the apical plasma membrane of NEB cells, and membrane or sub-membrane regions in H146 cells. NEB and H146 cells expressed all NOX proteins except NOX3, as well as all K(+)O(2) channels, except Kv1.5 and Kv4.3. Co-immunoprecipitation using Western blot multicolor Quantum dot labeling showed NOX2 molecular complexes with Kv but not with TASK, while NOX4 associated with TASK1 but not with Kv channel proteins. Hypoxia -induced serotonin release was inhibited in H 146 cells by siRNA to NOX2, while siRNA to NOX4 had only a partial effect, implicating NOX 2 as the predominant NEB cell O(2) sensor. Present findings support NEB cell specific plasma membrane model of O(2) sensing, and suggest unique NOX/K(+)O(2) channel combinations for diverse physiological NEB functions.
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PMID:The role of NOX2 and "novel oxidases" in airway chemoreceptor O(2) sensing. 1953 8

Angiotensin II promotes liver fibrogenesis by stimulating nonphagocytic NADPH oxidase (NOX)-induced oxidative stress. Angiotensin II type 1 (AT1) receptor blockers attenuate experimental liver fibrosis, yet their effects in human liver fibrosis are unknown. We investigated the effects of losartan on hepatic expression of fibrogenic, inflammatory, and NOX genes in patients with chronic hepatitis C (CHC). Fourteen patients with CHC and liver fibrosis received oral losartan (50 mg/day) for 18 mo. Liver biopsies were performed at baseline and after treatment. The degree of inflammation and fibrosis was evaluated by histological analysis (METAVIR). Collagen content was measured by morphometric quantification of Sirius red staining. Overall collagen content and fibrosis stage remained stable in the whole series, yet the fibrosis stage decreased in seven patients. Inflammatory activity improved in seven patients. The effect of losartan on hepatic expression of 31 profibrogenic and inflammatory genes and components of the NOX complex was assessed by quantitative PCR. Losartan treatment was associated with a significant decrease in the expression of several profibrogenic and NOX genes including procollagen alpha1(I) and alpha1(IV), urokinase-type plasminogen activator, metalloproteinase type 2, NOX activator 1 (NOXA-1) and organizer 1 (NOXO-1), and Rac-1. Losartan was well tolerated in all patients and was effective in attenuating the activity of the systemic renin-angiotensin system. No effects on serum liver tests or viral load were observed. We conclude that prolonged administration of losartan, an oral AT1 receptor blocker, is associated with downregulation of NOX components and fibrogenic genes in patients with CHC. Controlled studies are warranted to assess the effect of AT1 receptor blockers in chronic liver injury.
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PMID:Effects of losartan on hepatic expression of nonphagocytic NADPH oxidase and fibrogenic genes in patients with chronic hepatitis C. 1962 56

Reactive oxygen species (ROS) have been implicated in many intra- and intercellular processes. High levels of ROS are generated as part of the innate immunity in the respiratory burst of phagocytic cells. Low levels of ROS, however, are generated in a highly controlled manner by various cell types to act as second messengers in redox-sensitive pathways. A NADPH oxidase has been initially described as the respiratory burst enzyme in neutrophils. Stimulation of this complex enzyme system requires specific signaling cascades linking it to membrane-receptor activation. Subsequently, a family of NADPH oxidases has been identified in various nonphagocytic cells. They mainly differ in containing one out of seven homologous catalytic core proteins termed NOX1 to NOX5 and DUOX1 or 2. NADPH oxidase activity is controlled by regulatory subunits, including the NOX regulators p47phox and p67phox, their homologs NOXO1 and NOXA1, or the DUOX1 or 2 regulators DUOXA1 and 2. In addition, the GTPase Rac modulates activity of several of these enzymes. Recently, additional proteins have been identified that seem to have a regulatory function on NADPH oxidase activity under certain conditions. We will thus summarize molecular pathways linking activation of different membrane-bound receptors with increased ROS production of NADPH oxidases.
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PMID:Receptor activation of NADPH oxidases. 2000 46

Reactive oxygen species (ROS) play an important role in ethanol-induced apoptosis and teratogenesis. However, the major sources of ROS in ethanol-exposed embryos have remained undefined. This study was conducted to determine the role of NADPH oxidase (NOX) in ethanol-induced oxidative stress and apoptosis in mouse embryos. Analyses of mRNA expression indicated that ethanol treatment resulted in a significant increase in mRNA expression of NOX catalytic subunit Duox-1 in gestational day 9 (GD 9:0) mouse embryos. Ethanol exposure also resulted in significant increases in mRNA expression of NOX regulatory subunits, p22phox, p67phox, NOXA1 and NOXO1. In addition, a significant increase in NOX enzyme activity was found in the ethanol-exposed embryos as compared to controls. Co-treatment with the NOX inhibitor, diphenyleneiodonium (DPI), significantly prevented ethanol-induced increases in NOX enzyme activity, ROS generation and oxidative DNA damage in ethanol-exposed embryos. DPI treatment also resulted in a reduction in caspase-3 activation, decreased caspase-3 activity and diminished prevalence of apoptosis in ethanol-exposed embryos. These results support the hypothesis that NOX is a critical source of ROS in ethanol-exposed embryos and that it plays an important role in ethanol-induced oxidative stress and pathogenesis.
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PMID:The role of NOX enzymes in ethanol-induced oxidative stress and apoptosis in mouse embryos. 2002 59

NADPH oxidase activator 1 (NOXA1) together with NADPH oxidase organizer 1 (NOXO1) are key regulatory subunits of the NADPH oxidase NOX1. NOX1 is expressed mainly in colon epithelial cells and could be involved in mucosal innate immunity by producing reactive oxygen species (ROS). Contrary to its phagocyte counterpart NOX2, the mechanisms involved in NOX1 activation and regulation remain unclear. Here we report that NOX1 activity is regulated through MAP kinase (MAPK), protein kinase C (PKC), and protein kinase A (PKA)-dependent phosphorylation of NOXA1. We identified Ser-282 as target of MAPK and Ser-172 as target of PKC and PKA in vitro and in a transfected human embryonic kidney 293 (HEK293) cell model using site directed mutagenesis and phosphopeptide mapping analysis. In HEK293 cells, phosphorylation of these sites occurred at a basal level and down-regulated constitutive NOX1 activity. Indeed, S172A and S282A single mutants of NOXA1 significantly up-regulated constitutive NOX1-derived ROS production, and S172A/S282A double mutant further increased it, as compared to wild-type NOXA1. Furthermore, phosphorylation of NOXA1 on Ser-282 and Ser-172 decreased its binding to NOX1 and Rac1. These results demonstrated a critical role of NOXA1 phosphorylation on Ser-282 and Ser-172 in preventing NOX1 hyperactivation through the decrease of NOXA1 interaction to NOX1 and Rac1.
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PMID:Phosphorylation of NADPH oxidase activator 1 (NOXA1) on serine 282 by MAP kinases and on serine 172 by protein kinase C and protein kinase A prevents NOX1 hyperactivation. 2011 Feb 67


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