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)

Autophosphorylation of the platelet-derived growth factor (PDGF) receptor triggers intracellular signaling cascades as a result of recruitment of Src homology 2 domain-containing enzymes, including phosphatidylinositol 3-kinase (PI3K), the GTPase-activating protein of Ras (GAP), the protein-tyrosine phosphatase SHP-2, and phospholipase C-gamma1 (PLC-gamma1), to specific phosphotyrosine residues. The roles of these various effectors in PDGF-induced generation of H(2)O(2) have now been investigated in HepG2 cells expressing various PDGF receptor mutants. These mutants included a kinase-deficient receptor and receptors in which various combinations of the tyrosine residues required for the binding of PI3K (Tyr(740) and Tyr(751)), GAP (Tyr(771)), SHP-2 (Tyr(1009)), or PLC-gamma1 (Tyr(1021)) were mutated to Phe. PDGF failed to increase H(2)O(2) production in cells expressing either the kinase-deficient mutant or a receptor in which the two Tyr residues required for the binding of PI3K were replaced by Phe. In contrast, PDGF-induced H(2)O(2) production in cells expressing a receptor in which the binding sites for GAP, SHP-2, and PLC-gamma1 were all mutated was slightly greater than that in cells expressing the wild-type receptor. Only the PI3K binding site was alone sufficient for PDGF-induced H(2)O(2) production. The effect of PDGF on H(2)O(2) generation was blocked by the PI3K inhibitors LY294002 and wortmannin or by overexpression of a dominant negative mutant of Rac1. These results suggest that a product of PI3K is required for PDGF-induced production of H(2)O(2) in nonphagocytic cells, and that Rac1 mediates signaling between the PI3K product and the putative NADPH oxidase.
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PMID:Platelet-derived growth factor-induced H(2)O(2) production requires the activation of phosphatidylinositol 3-kinase. 1074 45

Signal regulatory protein alpha (SIRPalpha) is a glycoprotein receptor that recruits and signals via the tyrosine phosphatases SHP-1 and SHP-2. In macrophages SIRPalpha can negatively regulate the phagocytosis of host cells and the production of tumor necrosis factor alpha. Here we provide evidence that SIRPalpha can also stimulate macrophage activities, in particular the production of nitric oxide (NO) and reactive oxygen species. Ligation of SIRPalpha by antibodies or soluble CD47 triggers inducible nitric oxide synthase expression and production of NO. This was not caused by blocking negative-regulatory SIRPalpha-CD47 interactions. SIRPalpha-induced NO production was prevented by inhibition of the tyrosine kinase JAK2. JAK2 was found to associate with SIRPalpha in macrophages, particularly after SIRPalpha ligation, and SIRPalpha stimulation resulted in JAK2 and STAT1 tyrosine phosphorylation. Furthermore, SIRPalpha-induced NO production required the generation of hydrogen peroxide (H(2)O(2)) by a NADPH oxidase (NOX) and the phosphatidylinositol 3-kinase (PI3-K)-dependent activation of Rac1, an intrinsic NOX component. Finally, SIRPalpha ligation promoted SHP-1 and SHP-2 recruitment, which was both JAK2 and PI3-K dependent. These findings demonstrate that SIRPalpha ligation induces macrophage NO production through the cooperative action of JAK/STAT and PI3-K/Rac1/NOX/H(2)O(2) signaling pathways. Therefore, we propose that SIRPalpha is able to function as an activating receptor.
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PMID:Signal regulatory protein alpha ligation induces macrophage nitric oxide production through JAK/STAT- and phosphatidylinositol 3-kinase/Rac1/NAPDH oxidase/H2O2-dependent pathways. 1605 27

Epidermal growth factor (EGF) and endothelin-1 (ET-1) have been shown to be involved in proliferation and autoregeneration of renal tubular cells. This study aims to investigate the regulatory mechanism of ET-1-mediated EGF receptor (EGFR) transactivation in rat renal tubular cells (NRK-52E). Exposure of NRK-52E cells to ET-1 was found to stimulate the phosphorylation of EGFR and induce reactive oxygen species (ROS) generation. Both NAD(P)H oxidase inhibitor, diphenyliodonium (DPI) and ROS scavenger N-acetylcysteine (NAC), inhibited EGFR transactivation and extracellular signal-regulated kinase (ERK) phosphorylation caused by ET-1. In contrast, blockade of EGFR by AG1478 inhibited the phosphorylation of ERK but not ROS generation following ET-1 exposure. We found that the catalytic cysteine of Src homology 2-containing phosphotyrosine phosphatase (SHP-2) was transiently oxidized by ET-1 treatment in a modified malachite green phosphatase assay. In EGFR co-immunoprecipitation, SHP-2 was also found to interact with EGFR following ET-1 treatment. In SHP-2 knockdown NRK-52E cells, ET-1-induced EGFR transactivation was dramatically elevated and not influenced by NAC. However, GM6001 (an MMP inhibitor) and heparin binding (HB)-EGF neutralizing antibody suppressed this elevation. Our data suggest that ROS-mediated oxidation of SHP-2 is essential for HB-EGF-mediated EGFR transactivation in ET-1 signaling pathway in NRK-52E cells.
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PMID:Src homology 2-containing phosphotyrosine phosphatase regulates endothelin-1-induced epidermal growth factor receptor transactivation in rat renal tubular cell NRK-52E. 1626 33

Endothelin-1 (ET-1) is implicated in fibroblast proliferation, which results in cardiac fibrosis. Both reactive oxygen species (ROS) generation and epidermal growth factor receptor (EGFR) transactivation play critical roles in ET-1 signal transduction. In this study, we used rat cardiac fibroblasts treated with ET-1 to investigate the connection between ROS generation and EGFR transactivation. ET-1 treatment was found to stimulate the phosphorylation of EGFR and ROS generation, which were abolished by ETA receptor antagonist N-(N-(N-((hexahydro-1H-azepin-1-yl)carbonyl)-L-leucyl)-D-tryptophyl)-D-tryptophan (BQ485). NADPH oxidase inhibitor diphenyleneiodonium chloride (DPI), ROS scavenger N-acetyl cysteine (NAC), and p47phox small interfering RNA knockdown all inhibited the EGFR transactivation induced by ET-1. In contrast, EGFR inhibitor 4-(3'-chloroanilino)-6,7-dimethoxyquinazoline (AG-1478) cannot inhibit intracellular ROS generation induced by ET-1. Src homology 2-containing tyrosine phosphatase (SHP-2) was shown to be associated with EGFR during ET-1 treatment by EGFR coimmunoprecipitation. ROS have been reported to transiently oxidize the catalytic cysteine of phosphotyrosine phosphatases to inhibit their activity. We examined the effect of ROS on SHP-2 in cardiac fibroblasts using a modified malachite green phosphatase assay. SHP-2 was transiently oxidized during ET-1 treatment, and this transient oxidization could be repressed by DPI or NAC treatment. In SHP-2 knockdown cells, ET-1-induced phosphorylation of EGFR was dramatically elevated and is not influenced by NAC and DPI. However, this elevation was suppressed by GM6001 [a matrix metalloproteinase (MMP) inhibitor] and heparin binding (HB)-epidermal growth factor (EGF) neutralizing antibody. Our data suggest that ET-1-ETA-mediated ROS generation can transiently inhibit SHP-2 activity to facilitate the MMP-dependent and HB-EGF-stimulated EGFR transactivation and mitogenic signal transduction in rat cardiac fibroblasts.
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PMID:Reactive oxygen species generation is involved in epidermal growth factor receptor transactivation through the transient oxidization of Src homology 2-containing tyrosine phosphatase in endothelin-1 signaling pathway in rat cardiac fibroblasts. 1639 Dec 41

H(2)O(2) produced by stimulation of the macrophage NADPH oxidase is involved both in bacterial killing and as a second messenger in these cells. Protein tyrosine phosphatases (PTPs) are targets for H(2)O(2) signaling through oxidation of their catalytic cysteine, resulting in inhibition of their activity. Here, we show that, in the rat alveolar macrophage NR8383 cell line, H(2)O(2) produced through the ADP-stimulated respiratory burst induces the formation of a disulfide bond between PTP1B and GSH that was detectable with an antibody to glutathione-protein complexes and was reversed by DTT addition. PTP1B glutathionylation was dependent on H(2)O(2) as the presence of catalase at the time of ADP stimulation inhibited the formation of the conjugate. Interestingly, other PTPs, i.e., SHP-1 and SHP-2, did not undergo glutathionylation in response to ADP stimulation of the respiratory burst, although glutathionylation of these proteins could be shown by reaction with 25 mM glutathione disulfide in vitro. While previous studies have suggested the reversible oxidation of PTP1B during signaling or showed PTP1B glutathionylation in vitro, the present study directly demonstrates that physiological stimulation of H(2)O(2) production results in PTP1B glutathionylation in intact cells, which may affect downstream signaling.
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PMID:Stimulation of the alveolar macrophage respiratory burst by ADP causes selective glutathionylation of protein tyrosine phosphatase 1B. 1678 56

Platelet-derived growth factor (PDGF) plays a critical role in the pathogenesis of proliferative diseases. NAD(P)H oxidase (Nox)-derived reactive oxygen species (ROS) are essential for signal transduction by growth factor receptors. Here we investigated the dependence of PDGF-AA-induced ROS production on the cytosolic Nox subunits Rac-1 and p47(phox), and we systematically evaluated the signal relay mechanisms by which the alphaPDGF receptor (alphaPDGFR) induces ROS liberation. Stimulation of the alphaPDGFR led to a time-dependent increase of intracellular ROS levels in fibroblasts. Pharmacological inhibitor experiments and enzyme activity assays disclosed Nox as the source of ROS. alphaPDGFR activation is rapidly followed by the translocation of p47(phox) and Rac-1 from the cytosol to the cell membrane. Experiments performed in p47(phox)(-/-) cells and inhibition of Rac-1 or overexpression of dominant-negative Rac revealed that these Nox subunits are required for PDGF-dependent Nox activation and ROS liberation. To evaluate the signaling pathway mediating PDGF-AA-dependent ROS production, we investigated Ph cells expressing mutant alphaPDGFRs that lack specific binding sites for alphaPDGFR-associated signaling molecules (Src, phosphatidylinositol 3-kinase (PI3K), phospholipase Cgamma, and SHP-2). Lack of PI3K signaling (but not Src, phospholipase Cgamma, or SHP-2) completely abolished PDGF-dependent p47(phox) and Rac-1 translocation, increase of Nox activity, and ROS production. Conversely, a mutant alphaPDGFR able to activate only PI3K was sufficient to mediate these subcellular events. Furthermore, the catalytic PI3K subunit p110alpha (but not p110beta) was identified as the crucial isoform that elicits alphaPDGFR-mediated production of ROS. Finally, bromodeoxyuridine incorporation and chemotaxis assays revealed that the lack of ROS liberation blunted PDGF-AA-dependent chemotaxis but not cell cycle progression. We conclude that PI3K/p110alpha mediates growth factor-dependent ROS production by recruiting p47(phox) and Rac-1 to the cell membrane, thereby assembling the active Nox complex. ROS are required for PDGF-AA-dependent chemotaxis but not proliferation.
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PMID:Phosphatidylinositol 3-kinase-dependent membrane recruitment of Rac-1 and p47phox is critical for alpha-platelet-derived growth factor receptor-induced production of reactive oxygen species. 1807 Aug 87

Angiotensin II (Ang II) signaling in vascular smooth muscle cells (VSMCs) involves reactive oxygen species (ROS) through unknown mechanisms. We propose that Ang II induces phosphorylation of growth signaling kinases by redox-sensitive regulation of protein tyrosine phosphatases (PTP) in VSMCs and that augmented Ang II signaling in spontaneously hypertensive rats (SHRs) involves oxidation/inactivation and blunted phosphorylation of the PTP, SHP-2. PTP oxidation was assessed by the in-gel PTP method. SHP-2 expression and activity were evaluated by immunoblotting and by a PTP activity assay, respectively. SHP-2 and Nox1 were downregulated by siRNA. Ang II induced oxidation of multiple PTPs, including SHP-2. Basal SHP-2 content was lower in SHRs versus WKY. Ang II increased SHP-2 phosphorylation and activity with blunted responses in SHRs. Ang II-induced SHP-2 effects were inhibited by valsartan (AT(1)R blocker), apocynin (NAD(P)H oxidase inhibitor), and Nox1 siRNA. Ang II stimulation increased activation of ERK1/2, p38MAPK, and AKT, with enhanced effects in SHR. SHP-2 knockdown resulted in increased AKT phosphorylation, without effect on ERK1/2 or p38MAPK. Nox1 downregulation attenuated Ang II-mediated AKT activation in SHRs. Hence, Ang II regulates PTP/SHP-2 in VSMCs through AT(1)R and Nox1-based NAD(P)H oxidase via two mechanisms, oxidation and phosphorylation. In SHR Ang II-stimulated PTP oxidation/inactivation is enhanced, basal SHP-2 expression is reduced, and Ang II-induced PTP/SHP-2 phosphorylation is blunted. These SHP-2 actions are associated with augmented AKT signaling. We identify a novel redox-sensitive SHP-2-dependent pathway for Ang II in VSMCs. SHP-2 dysregulation by increased Nox1-derived ROS in SHR is associated with altered Ang II-AKT signaling.
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PMID:Redox-sensitive signaling by angiotensin II involves oxidative inactivation and blunted phosphorylation of protein tyrosine phosphatase SHP-2 in vascular smooth muscle cells from SHR. 1856 42

The trapping of lipid-laden macrophages in the arterial intima is a critical but reversible step in atherogenesis. However, the mechanism by which this occurs is not clearly defined. Here, we tested in mice the hypothesis that CD36, a class B scavenger receptor expressed on macrophages, has a role in this process. Using both in vivo and in vitro migration assays, we found that oxidized LDL (oxLDL), but not native LDL, inhibited migration of WT mouse macrophages but not CD36-deficient cells. We further observed a crucial role for CD36 in modulating the in vitro migratory response of human peripheral blood monocyte-derived macrophages to oxLDL. oxLDL also induced rapid spreading and actin polymerization in CD36-sufficient but not CD36-deficient mouse macrophages in vitro. The underlying mechanism was dependent on oxLDL-mediated CD36 signaling, which resulted in sustained activation of focal adhesion kinase (FAK) and inactivation of Src homology 2-containing phosphotyrosine phosphatase (SHP-2). The latter was due to NADPH oxidase-mediated ROS generation, resulting in oxidative inactivation of critical cysteine residues in the SHP-2-active site. Macrophage migration in the presence of oxLDL was restored by both antioxidants and NADPH oxidase inhibitors, which restored the dynamic activation of FAK. We conclude therefore that CD36 signaling in response to oxLDL alters cytoskeletal dynamics to enhance macrophage spreading, inhibiting migration. This may induce trapping of macrophages in the arterial intima and promote atherosclerosis.
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PMID:CD36 modulates migration of mouse and human macrophages in response to oxidized LDL and may contribute to macrophage trapping in the arterial intima. 1950 73

Urotensin II (U-II) is implicated in vascular smooth muscle cell proliferation, which results in vascular remodeling. We recently demonstrated that both reactive oxygen species (ROS) generation and epidermal growth factor receptor (EGFR) transactivation play critical roles in U-II signal transduction. However, the detailed intracellular mechanism of U-II in vascular smooth muscle cells remains unclear. In this study, we used rat aortic smooth muscle cells treated with U-II to investigate the connection between ROS generation and EGFR transactivation. U-II treatment was found to stimulate endothelin-1 (ET-1) expression and cell proliferation through the phosphorylation of EGFR and ROS generation. NAD(P)H oxidase inhibitor apocynin and ROS scavenger N-acetylcysteine (NAC) inhibited the EGFR transactivation induced by U-II. In contrast, AG-1478 (an EGFR inhibitor) failed to inhibit intracellular ROS generation induced by U-II. Src homology 2-containing tyrosine phosphatase (SHP-2) was shown to be associated with EGFR during U-II treatment by EGFR coimmunoprecipitation. ROS have been reported to oxidize the catalytic cysteine of SHP-2 and inhibit its activity. We examined the effect of U-II on SHP-2 in smooth muscle cells using a modified malachite green phosphatase assay. SHP-2 was oxidized during U-II treatment; and this oxidization could be repressed by NAC treatment. In SHP-2 knockdown cells, U-II-induced EGFR phosphorylation, ET-1 secretion, and cell proliferation were enhanced, and were not influenced by NAC. Our data suggest that U-II-mediated ROS generation can inhibit SHP-2 activity to facilitate the EGFR transactivation and mitogenic signal transduction in rat aortic smooth muscle cells.
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PMID:Urotensin II-induced endothelin-1 expression and cell proliferation via epidermal growth factor receptor transactivation in rat aortic smooth muscle cells. 1926 34

Several protein phosphatases are involved in neuroprotection in response to ischemic brain injury. Here, we report that reactive oxygen species (ROS)-mediated oxidative stress promotes phosphorylation of endogenous SHP-2 through lipid rafts in rat primary astrocytes. SHP-2 was transiently phosphorylated during hypoxia/reoxygenation, an effect abrogated by a ROS scavenger and an NADPH oxidase inhibitor. Additionally, exogenous treatment with hydrogen peroxide (H(2)O(2)) triggered SHP-2 phosphorylation in a time- and dose-dependent manner and led to its translocation into lipid rafts. H(2)O(2)-mediated SHP-2 phosphorylation and translocation were inhibited by filipin III and methyl-beta-cyclodextrin (MCD), lipid-raft-disrupting agents. In the presence of H(2)O(2), SHP-2 formed a complex with STAT-3 and reduced the steady-state STAT-3 phosphorylation level. Interestingly, the effect of H(2)O(2) on SHP-2 phosphorylation was cell-type specific. Remarkably, SHP-2 phosphorylation was induced strongly by H(2)O(2) in astrocytes, but barely detectable in microglia. Our results collectively indicate that SHP-2 is activated by ROS-mediated oxidative stress in astrocytes and functions as a component of the raft-mediated signaling pathway that acts through dephosphorylation and inactivation of other phosphotyrosine proteins, such as STAT-3.
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PMID:Oxidative stress induces lipid-raft-mediated activation of Src homology 2 domain-containing protein-tyrosine phosphatase 2 in astrocytes. 1934 36


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