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)

Vascular NAD(P)H oxidase activity contributes to oxidative stress. Thiol oxidants inhibit leukocyte NADPH oxidase. To assess the role of reactive thiols on vascular oxidase, rabbit iliac/carotid artery homogenates were incubated with distinct thiol reagents. NAD(P)H-driven enzyme activity, assessed by lucigenin (5 or 250 microM) luminescence, was nearly completely (> 97%) inhibited by the oxidant diamide (1mM) or the alkylator p-chloromercuryphenylsulfonate (pCMPS, 0.5mM). Analogous inhibition was also shown with EPR spectroscopy using DMPO as a spin trap. The oxidant dithionitrobenzoic acid (0.5mM) inhibited NADPH-driven signals by 92% but had no effect on NADH-driven signals. In contrast, the vicinal dithiol ligand phenylarsine oxide (PAO, 1 microM) induced minor nonsignificant inhibition of NADPH-driven activity, but significant stimulation of NADH-triggered signals. The alkylator N-ethyl maleimide (NEM, 0.5mM) or glutathione disulfide (GSSG, 3mM) had no effect with each substrate. Coincubation of N-acetylcysteine (NAC, 3mM) with diamide or pCMPS reversed their inhibitory effects by 30-60%, whereas NAC alone inhibited the oxidase by 52%. Incubation of intact arterial rings with the above reagents disclosed similar results, except that PAO became inhibitor and NAC stimulator of NADH-driven signals. Notably, the cell-impermeant reagent pCMPS was also inhibitory in whole rings, suggesting that reactive thiol(s) affecting oxidase activity are highly accessible. Since lack of oxidase inhibition by NEM or GSSG occurred despite significant cellular glutathione depletion, change in intracellular redox status is not sufficient to account for oxidase inhibition. Moreover, the observed differences between NADPH and NADH-driven oxidase activity point to complex or multiple enzyme forms.
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PMID:Inhibition of vascular NADH/NADPH oxidase activity by thiol reagents: lack of correlation with cellular glutathione redox status. 1106 14

Laminar shear stress activates NADPH oxidase in vascular endothelial cells (ECs), and the generated superoxide radicals (O2(-.) are known to be involved in intercellular adhesion molecule (ICAM)-1 expression. In this study, the role of a glycosphingolipid (GSL), lactosylceramide (LacCer), as a second messenger in the shear-induced O2(-.) generation and ICAM-1 expression was examined. It is known that glucosylceramide synthase (GlcT-1) catalyzes the synthesis of glucosylceramide (GlcCer) from ceramide, and subsequently lactosylceramide synthase (GalT-2) synthesizes LacCer from GlcCer. We observed that exposing cultured human umbilical vein ECs (HUVECs) to fluid shear stress (20 dyn/cm(2) for 30 min) activated GalT-2. Shear stress also increased EC O2(-.) generation, that peaked at 30 min, and surface ICAM-1 protein expression at 6 h post-shear. EC preincubation with the antioxidant N-acetylcysteine (NAC; 20 mM for 2 h) completely abolished the shear-induced O2(-.) production and significantly inhibited ICAM-1 expression. EC preincubation with D-1-phenyl-2-decanoylamino-3-morpholino-1-propanol (D-PDMP), an inhibitor of the GSL glycosyltransferases GlcT-1 and GalT-2, abrogated the shear-induced activation of GalT-2. D-PDMP also abolished the shear-induced O2(-.) production and ICAM-1 expression. We conclude that laminar shear stress activates GalT-2 to produce LacCer. In turn, LacCer activates NADPH oxidase, which produces O2(-.), and O2(-.) mediates the shear-induced increase in ICAM-1 expression. Thus, LacCer may play an important role in hemodynamic force-induced pathological conditions, such as atherosclerosis and ischemia/reperfusion injury.
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PMID:Lactosylceramide mediates shear-induced endothelial superoxide production and intercellular adhesion molecule-1 expression. 1174 Jan 54

In vascular smooth muscle cells, reactive oxygen species (ROS) were known to mediate platelet-derived growth factor (PDGF)-induced cell proliferation and NADH/NADPH oxidase is the major source of ROS. NADH/NADPH oxidase is controlled by rac1 in non-phagocytic cells. In this study, we examined whether the inhibition of rac1 by adenoviral-mediated gene transfer of a dominant negative rac1 gene product (Ad.N17rac1) could reduce the proliferation of rat aortic vascular smooth muscle cells (RASMC) stimulated by PDGF via decreasing intracellular ROS. RASMC were stimulated by PDGF (80 ng/mL) with or without N-acetylcysteine 1 mM or infected with 100 mutiplicity of infection of Ad.N17rac1. Intracellular ROS levels were measured at 12 hr using carboxyl-2', 7'-dichlorodihydrofluorescein diacetate confocal microscopy. At 72 hr, cellular proliferation was evaluated by cell number counting and XTT assay. Compared with control, ROS levels were increased by 2-folds by PDGF. NAC and Ad.N17rac1 inhibited PDGF-induced increase of ROS by 77% and 65%, respectively. Cell number was increased by PDGF by 1.6-folds compared with control. NAC and Ad.N17rac1 inhibited PDGF-induced cellular growth by 45% and 87%, respectively. XTT assay also showed similar results. We concluded that inhibition of rac1 in RASMCs could reduce intracellular ROS levels and cellular proliferation induced by PDGF.
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PMID:Inhibition of rac1 reduces PDGF-induced reactive oxygen species and proliferation in vascular smooth muscle cells. 1174 50

Lysophosphatidylcholine (lysoPC) acts on vascular smooth muscle cells (VSMCs) to produce a mitogenic response through the activation of extracellular signal-regulated kinases 1/2 (ERK1/2). In the present study, we examined the importance of reactive oxygen species (ROS) in lysoPC-stimulated ERK1/2 activation in cultured rat VSMCs. Treatment with lysoPC for 3 minutes caused a 2-fold increase in intracellular ROS that was blocked by the NADH/NADPH oxidase inhibitor, diphenylene iodonium (DPI). Antioxidants, N-acetyl-L-cysteine, glutathione monoester, or alpha -tocopherol, inhibited ERK1/2 activation by lysoPC. Almost identical results were obtained in the VSMC line A10. Pretreatment of VSMCs with DPI but not allopurinol or potassium cyanide (KCN) abrogated the activation of ERK1/2. The Flag-tagged p47phox expressed in A10 cells was translocated from the cytosol to the membrane after 2 minutes of stimulation with lysoPC. The overexpression of dominant-negative p47phox in A10 cells suppressed lysoPC-induced ERK activation. The ROS-dependent ERK activation by lysoPC seems to involve protein kinase C- and Ras-dependent raf-1 activation. Induction of c-fos expression and enhanced AP-1 binding activity by lysoPC were also inhibited by DPI and NAC. Taken together, these data suggest that ROS generated by NADH/NADPH oxidase contribute to lysoPC-induced activation of ERK1/2 and subsequent growth promotion in VSMCs.
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PMID:Lysophosphatidylcholine activates extracellular signal-regulated kinases 1/2 through reactive oxygen species in rat vascular smooth muscle cells. 1200 86

We examined the mechanism of action of lysophosphatidylcholine (lyso-PC), which is suggested to be involved in the pathogenesis of atherosclerosis and inflamatory disorders, and its interaction with well-known vasoactive compounds such as hydrogen peroxide (H2O2), thromboxane A2 (TX-A2), serotonin (5-HT), angiotensin II (Ang-II), endothelin-1 (ET-1), or urotensin II (U-II) on VSMC proliferation. Growth-arrested rabbit VSMCs were incubated with given concentrations of lyso-PC with H202, TX-A2, 5-HT, Ang-II, ET-1, or U-II. [3H]Thymidine incorporation into DNA was measured as an index of VSMC proliferation. Lyso-PC induced a maximal effect on [3H]thymidine incorporation at a concentration of 15 microM (156%), and its effect was significantly inhibited by the phospholipase C inhibitor U73122 (10 microM), the intracellular antioxidant NAC (400 microM), and the NADPH oxidase inhibitor diphenylene iodonium (1 microM), but not by the MAPK kinase inhibitor (10 microM). H2O2, TX-A2, 5-HT, Ang-II, ET-1, or U-II also stimulated [3H]thymidine incorporation in a dose-dependent manner. A non-mitogenic concentration of lyso-PC (5 microM) significantly potentiated the effect of low concentrations of H2O2 (0.1 microM, 110 to 222%), TX-A2 (5 microM, 120 to 202%), 5-HT (5 microM, 182 to 259%), Ang-II (0.5 microM, 167 to 304%), ET-1 (0.01 microM, 139 to 297%), or U-II (0.025 microM, 120 to 332%) on [3H]thymidine incorporation. The results suggest that lyso-PC acts synergistically with the vasoactive compounds H2O2, TX-A2, 5-HT, Ang-II, ET-1, or U-II in inducing VSMC proliferation, which may play an important role in the progression of atherosclerosis.
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PMID:Lysophosphatidylcholine potentiates the mitogenic effect of various vasoactive compounds on rabbit aortic smooth muscle cells. 1222 16

Hyperhomocysteinemia is an independent risk factor for cardiovascular diseases, although the mechanism leading to vascular dysfunction is not clear. The aim of this study was to examine the effect of homocysteine (Hcy) on oxi-dative stress and apoptosis in human umbilical vein endothelial cells (HUVECs). HUVECs were challenged for 24 h with Hcy (10 microM-3 mM) in the presence of various stress signaling inhibitors, including the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor apocynin (100 microM), the p38 mito-gen-activated protein kinase inhibitor SB203580 (2.5 microM), the extracellular signal-regulated kinase inhibitor U0126 (2.5 microM), the stress-activated protein kinase (SAPK)/c-Jun NH2-terminal kinase (JNK) inhibitor JNK inhibitor II (10 microM), and antioxidants alpha-tocopherol (5 microg/mL) and N-acetyl cysteine (NAC, 2 mM). Reactive oxygen species (ROS) were detected using 5-(6)-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate. Apoptosis was evaluated by 4',6'-diamidino-2'-phenylindoladihydrochloride staining, annexin-V phosphatidyl- serine/propidium iodide, and caspase-3 assay. NADPH oxidase and SAPK/JNK signal were evaluated with immunoblotting. Hcy significantly enhanced ROS generation and apoptosis after 24-h incubation. Apocynin prevented Hcy-induced ROS generation but only partially restored Hcy-induced apoptosis. JNK inhibitor II, alpha-tocopherol, and NAC partially reduced Hcy-induced apoptosis, although SB203580 and U0126 had no effect. Immunoblotting analysis confirmed upregulation of NADPH oxidase and SAPK/JNK signaling. Collectively, our results suggested that Hcy may induce oxidative stress and apopto-sis through an NADPH oxidase and/or JNK-dependent mechanism(s).
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PMID:Possible involvement of NADPH oxidase and JNK in homocysteine-induced oxidative stress and apoptosis in human umbilical vein endothelial cells. 1573 81

TGF-beta produced by keratinocytes in response to UVB (290-320 nm) is a potential mediator for effects of acute and chronic solar radiation on skin. This study was designed to determine whether reactive oxygen species (ROS) mediate UVB-induced TGF-beta biosynthesis in keratinocytes and the subsequent activation of the latent TGF-beta complex. UVB irradiation elevated both total (latent plus active) and active TGF-beta in the keratinocyte supernatants, with a greater increase in the active form. UVB irradiation induced up to a 30% increase in ROS, and the ROS were detected up to 90 min after irradiation. NAC and Trolox, cytoplasmic ROS scavengers, abolished the UVB-induced TGF-beta and intracellular ROS, suggesting that UVB-induced ROS are involved in TGF-beta regulation. Inhibitors of NADPH oxidase activity, DPI and apocynin, decreased UVB-induced ROS. The increase in NADPH oxidase activity was mediated by EGFR activation. UVB-induced ROS also activated latent TGF-beta complex by stimulating MMP-2 and -9 activities. In summary, physiological doses of UVB increase intracellular ROS, which upregulate TGF-beta biosynthesis and activation of TGF-beta through increased activity of MMPs.
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PMID:Involvement of UVB-induced reactive oxygen species in TGF-beta biosynthesis and activation in keratinocytes. 1574 85

Previous studies have shown that N-methyl-D-aspartate (NMDA) receptor activation results in production of reactive oxygen species (ROS) and activation of extracellular signal-regulated kinase (ERK) in hippocampal area CA1. In addition, application of ROS to hippocampal slices has been shown to result in activation of ERK in area CA1. To determine whether these events were linked causally, we investigated whether ROS are required for NMDA receptor-dependent activation of ERK. In agreement with previous studies, we found that treatment of hippocampal slices with NMDA resulted in activation of ERK in area CA1. The NMDA receptor-dependent activation of ERK was either blocked or attenuated by a number of antioxidants, including the general antioxidant N-acetyl-L-cysteine (L-NAC), the superoxide-scavenging enzyme superoxide dismutase (SOD), the membrane-permeable SOD mimetic Mn(III) tetrakis (4-benzoic acid) porphyrin (MnTBAP), the hydrogen peroxide-scavenging enzyme catalase, and the catalase mimetic ebselen. The NMDA receptor-dependent activation of ERK also was blocked by the NADPH oxidase inhibitor diphenylene iodonium (DPI) and was absent in mice that lacked p47(phox), one of the required protein components of NADPH oxidase. Taken together, our results suggest that ROS production, especially superoxide production via NADPH oxidase, is required for NMDA receptor-dependent activation of ERK in hippocampal area CA1.
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PMID:NADPH oxidase is required for NMDA receptor-dependent activation of ERK in hippocampal area CA1. 1599 81

Phenotypic differentiation of adventitial fibroblasts into myofibroblasts is an essential feature of vascular remodeling. The present study was undertaken to test the hypothesis that reactive oxygen species (ROS) are involved in rat adventitial fibroblast differentiation to myofibroblast. Activation of alpha-smooth muscle actin (alpha-SMA) was used as a marker of myofibroblast. Angiotensin II increased intracellular ROS in adventitial fibroblasts that was completely inhibited by the free radical scavenger NAC, the NAD(P)H oxidase inhibitor DPI, and transfection of antisense gp91phox oligonucleotides. Myofibroblast differentiation was prevented by inhibition of ROS generation with DPI, NAC, and antisense gp91phox as shown by decreased expression of alpha-SMA. Angiotensin II rapidly induced phosphorylation of p38 MAPK and JNK, both of which were inhibited by DPI, NAC, antisense gp91phox, and the selective AT1 receptor antagonist, losartan. Inhibiting p38MAPK with SB202190 or JNK with SP600125 also reduced angiotensin II-induced alpha-SMA expression. These findings demonstrate that angiotensin II induces adventitial fibroblast differentiation to myofibroblast via a pathway that involves NADPH oxidase generation of ROS and activation of p38MAPK and JNK pathways.
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PMID:NAD(P)H oxidase-derived reactive oxygen species regulate angiotensin-II induced adventitial fibroblast phenotypic differentiation. 1629 39

Although 2,4,6-trinitrotoluene (TNT) has been found to uncouple nitric oxide synthase (NOS), thereby leading to reactive oxygen species (ROS), cellular response against TNT still remains unclear. Exposure of bovine aortic endothelial cells (BAECs) to TNT (100 microM) resulted in serine 1179 phosphorylation of endothelial NOS (eNOS). With specific inhibitors (wortmannin and LY294002), we found that PI3K/Akt signaling participated in the eNOS phosphorylation caused by TNT, whereas the ERK pathway did not. ROS were generated following exposure of BAECs to TNT. However, TNT-mediated phosphorylation of either eNOS or Akt was drastically blocked by NAC and PEG-CAT. Interestingly, pretreatment with apocynin, a specific inhibitor for NADPH oxidase, diminished the phosphorylation of eNOS and Akt. These results suggest that TNT affects NADPH oxidase, thereby generating hydrogen peroxide, which is capable of activating PI3K/Akt signaling associated with eNOS Ser 1179 phosphorylation.
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PMID:Serine 1179 phosphorylation of endothelial nitric oxide synthase caused by 2,4,6-trinitrotoluene through PI3K/Akt signaling in endothelial cells. 1651 56


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