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)

Neutrophils are mobilized to the vascular wall during vessel inflammation. Published data are conflicting on phagocytic nicotinamide-adenine dinucleotide phosphate (NADPH) oxidase activation during the hypertensive state, and the capacity of angiotensin II (Ang II) to modulate the intracellular redox status has not been analyzed in neutrophils. We here describe that Ang II highly stimulates endogenous and extracellular O2- production in these cells, consistent with the translocation to the cell membrane of the cytosolic components of NADPH oxidase, p47phox, and p67phox. The Ang II-dependent O2- production was suppressed by specific inhibitors of AT1 receptors, of the p38MAPK and ERK1/2 pathways, and of flavin oxidases. Furthermore, Ang II induced a robust phosphorylation of p38MAPK, ERK1/2, and JNK1/2 (particularly JNK2), which was hindered by inhibitors of NADPH oxidase, tyrosine kinases, and ROS scavengers. Ang II increased cytosolic Ca2+ levels-released mainly from calcium stores-enhanced the synthesis de novo and activity of calcineurin, and stimulated the DNA-binding activity of the transcription factor NF-kappaB in cultured human neutrophils. Present data demonstrate for the first time a stimulatory role of Ang II in the activation of phagocytic cells, underscore the relevant role of ROS as mediators in this process, and uncover a variety of signaling pathways by which Ang II operates in human neutrophils.
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PMID:Oxidative stress is a critical mediator of the angiotensin II signal in human neutrophils: involvement of mitogen-activated protein kinase, calcineurin, and the transcription factor NF-kappaB. 1266 41

We investigated the role of receptor tyrosine kinases in Ang II-stimulated generation of reactive oxygen species (ROS) and assessed whether MAP kinase signaling by Ang II is mediated via redox-sensitive pathways. Production of ROS and activation of NADPH oxidase were determined by DCFDA (dichlorodihydrofluorescein diacetate; 2 micromol/L) fluorescence and lucigenin (5 micromol/L) chemiluminescence, respectively, in rat vascular smooth muscle cells (VSMC). Phosphorylation of ERK1/2, p38MAP kinase and ERK5 was determined by immunoblotting. The role of insulin-like growth factor-1 receptor (IGF-1R) and epidermal growth factor receptor (EGFR) was assessed with the antagonists AG1024 and AG1478, respectively. ROS bioavailability was manipulated with Tiron (10(-5) mol/L), an intracellular scavenger, and diphenylene iodinium (DPI; 10(-6) mol/L), an NADPH oxidase inhibitor. Ang II stimulated NADPH oxidase activity and dose-dependently increased ROS production (p < 0.05). These actions were reduced by AG1024 and AG1478. Ang II-induced ERK1/2 phosphorylation (276% of control) was decreased by AG1478 and AG1024. Neither DPI nor tiron influenced Ang II-stimulated ERK1/2 activity. Ang II increased phosphorylation of p38 MAP kinase (204% of control) and ERK5 (278% of control). These effects were reduced by AG1024 and AG1478 and almost abolished by DPI and tiron. Thus Ang II stimulates production of NADPH-inducible ROS partially through transactivation of IGF-1R and EGFR. Inhibition of receptor tyrosine kinases and reduced ROS bioavaliability attenuated Ang II-induced phosphorylation of p38 MAP kinase and ERK5, but not of ERK1/2. These findings suggest that Ang II activates p38MAP kinase and ERK5 via redox-dependent cascades that are regulated by IGF-1R and EGFR transactivation. ERK1/2 regulation by Ang II is via redox-insensitive pathways.
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PMID:Redox-dependent MAP kinase signaling by Ang II in vascular smooth muscle cells: role of receptor tyrosine kinase transactivation. 1271 May 30

Angiotensin II (Ang II), protein kinase C (PKC), reactive oxygen species (ROS) generated by NADPH oxidase, the activation of Janus kinase 2 (JAK2), and the polyol pathway play important parts in the hyperproliferation of vascular smooth muscle cells (VSMC), a characteristic feature of diabetic macroangiopathy. The precise mechanism, however, remains unclear. This study investigated the relation between the polyol pathway, PKC-beta, ROS, JAK2, and Ang II in the development of diabetic macroangiopathy. VSMC cultured in high glucose (HG; 25 mm) showed significant increases in the tyrosine phosphorylation of JAK2, production of ROS, and proliferation activities when compared with VSMC cultured in normal glucose (5.5 mm (NG)). Both the aldose reductase specific inhibitor (zopolrestat) or transfection with aldose reductase antisense oligonucleotide blocked the phosphorylation of JAK2, the production of ROS, and proliferation of VSMC induced by HG, but it had no effect on the Ang II-induced activation of these parameters in both NG and HG. However, transfection with PKC-beta antisense oligonucleotide, preincubation with a PKC-beta-specific inhibitor (LY379196) or apocynin (NADPH oxidase-specific inhibitor), or electroporation of NADPH oxidase antibodies blocked the Ang II-induced JAK2 phosphorylation, production of ROS, and proliferation of VSMC in both NG and HG. These observations suggest that the polyol pathway hyperactivity induced by HG contributes to the development of diabetic macroangiopathy through a PKC-beta-ROS activation of JAK2.
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PMID:High glucose augments the angiotensin II-induced activation of JAK2 in vascular smooth muscle cells via the polyol pathway. 1277 86

An elevation in angiotensin II (Ang II) levels is a common occurrence in a diverse number of cardiovascular diseases including hypertension, hypercholesterolaemia, atherosclerotic coronary artery disease, left ventricular hypertrophy (LVH), heart failure and diabetes. An important effect of Ang II is activation of the NAD(P)H oxidase, a major source of reactive oxygen species (ROS) production by vascular cells. This increase in cellular ROS contributes to the pathogenesis of vascular disease by altering endothelial cell function, enhancing smooth muscle cell growth and proliferation, stimulating inflammatory proteins, including macrophage chemoattractant agents, growth factors and cytokines, and modulating matrix remodelling. Studies of genetically-altered mice have unequivocally shown that activation of the NAD(P)H oxidase by Ang II contributes to hypertension, LVH and atherosclerosis. Furthermore, increasing evidence suggest that the NAD(P)H oxidase contributes to human disease, suggesting that it is a potential target for future therapeutic intervention.
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PMID:Interactions of angiotensin II with NAD(P)H oxidase, oxidant stress and cardiovascular disease. 1280 86

Enhanced tissue angiotensin (Ang) II levels have been reported in diabetes and might lead to cardiac dysfunction through oxidative stress. This study examined the effect of blocking the Ang II type 1 (AT1) receptor on high glucose-induced cardiac contractile dysfunction. Rat ventricular myocytes were maintained in normal- (NG, 5.5 mmol/L) or high- (HG, 25.5 mmol/L) glucose medium for 24 hours. Mechanical and intracellular Ca2+ properties were assessed as peak shortening (PS), time to PS (TPS), time to 90% relengthening (TR90), maximal velocity of shortening/relengthening (+/-dL/dt), and intracellular Ca2+ decay (tau). HG myocytes exhibited normal PS; decreased +/-dL/dt; and prolonged TPS, TR90, and tau. Interestingly, the HG-induced abnormalities were prevented with the AT1 blocker L-158,809 (10 to 1000 nmol/L) but not the Janus kinase-2 (JAK2) inhibitor AG-490 (10 to 100 micromol/L). The only effect of AT1 blockade on NG myocytes was enhanced PS at 1000 nmol/L. AT1 antagonist-elicited cardiac protection against HG was nullified by the NADPH oxidase activator sodium dodecyl sulfate (80 micromol/L) and mimicked by the NADPH oxidase inhibitors diphenyleneiodonium (10 micromol/L) or apocynin (100 micromol/L). Western blot analysis confirmed that the protein abundance of NADPH oxidase subunit p47phox and the AT1 but not the AT2 receptor was enhanced in HG myocytes. In addition, the HG-induced increase of p47phox was prevented by L-158,809. Enhanced reactive oxygen species production observed in HG myocytes was prevented by AT1 blockade or NADPH oxidase inhibition. Collectively, our data suggest that local Ang II, acting via AT1 receptor-mediated NADPH oxidase activation, is involved in hyperglycemia-induced cardiomyocyte dysfunction, which might play a role in diabetic cardiomyopathy.
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PMID:AT1 blockade prevents glucose-induced cardiac dysfunction in ventricular myocytes: role of the AT1 receptor and NADPH oxidase. 1284 13

1. Overproduction of superoxide anions in the vascular wall contributes to endothelial dysfunction in vascular disease. A superoxide-generating reduced beta-nicotinamide adenine dinucleotide phosphate (NADPH) oxidase has recently been identified as a major source of oxidative radicals in vascular tissues. We studied the effects of a synthetic manganese-containing superoxide dismutase (SOD) mimetic, M40403, on NADPH oxidase-dependent superoxide generation and on endothelial dysfunction. 2. In rat aortic smooth muscle cells, NADPH (100 micro M) markedly stimulated superoxide production as detected by lucigenin (5 micro M)-enhanced chemiluminescence. M40403 reduced NADPH oxidase-dependent superoxide production in a concentration-dependent manner, with IC(50) being 31.6 micro M. In contrast, native Cu/Zn SOD (up to 300 U ml(-1)) had no effect. Angiotensin II (100 nM) increased the NADPH oxidase activity by 70%, and treatment with M40403 (10 micro M) reduced this increased superoxide to the control level. 3. In aortae from apolipoprotein(E)-deficient mice (apoE(0)) with hyperlipidemia and atherosclerosis, superoxide production is largely derived from NADPH oxidase. The attenuation of endothelial nitric oxide vasodilator function parallels the increase in vascular superoxide production at different stages of the disease. Acute incubation of such aortic rings with M40403 significantly suppressed superoxide production and improved endothelium-dependent vasorelaxation to a level comparable to that in wildtype control mice. 4. In summary, the cell-permeable SOD mimetic M40403 was found to reverse endothelial dysfunction in apoE(0) aorta ex vivo by decreasing NADPH oxidase-dependent superoxide levels. The advantages of synthetic SOD mimetics over the native Cu/Zn SOD enzyme, such as greater cell permeability and stability, confer significant therapeutic potential in vascular disease.
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PMID:Superoxide dismutase mimetic M40403 improves endothelial function in apolipoprotein(E)-deficient mice. 1287 23

Angiotensin II contributes to ventricular remodeling by promoting both cardiac hypertrophy and apoptosis; however, the mechanism underlying the latter phenomenon is poorly understood. One possibility that has been advanced is that angiotensin II activates NADPH oxidase, generating free radicals that trigger apoptosis. In apparent support of this notion, it was found that angiotensin II-mediated apoptosis in the cardiomyocyte is blocked by the NADPH oxidase inhibitor diphenylene iodonium. However, three lines of evidence suggest that peroxynitrite, rather than superoxide, is responsible for angiotensin II-mediated DNA damage and apoptosis. First, the inducible nitric oxide inhibitor aminoguanidine prevents angiotensin II-induced DNA damage and apoptosis. Second, based on ligation-mediated PCR, the pattern of angiotensin II-induced DNA damage resembles peroxynitritemediated damage rather than damage caused by either superoxide or nitric oxide. Third, angiotensin II activates p53 through the phosphorylation of Ser15 and Ser20, residues that are commonly phosphorylated in response to DNA damage. It is proposed that angiotensin II promotes the oxidation of DNA, which in turn activates p53 to mediate apoptosis.
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PMID:Apoptotic cascade initiated by angiotensin II in neonatal cardiomyocytes: role of DNA damage. 1291 32

Intracellular signaling pathway mediated by small GTPase Rho and its effector Rho-kinase plays an important role in regulation of vascular smooth muscle contraction and other cellular functions. We have recently demonstrated that Rho-kinase is substantially involved in angiotensin II-induced gene expressions and various cellular responses in vitro. However, it remains to be examined whether Rho-kinase is involved in the angiotensin II-induced cardiovascular hypertrophy in vivo and, if so, what mechanisms are involved. Long-term infusion of angiotensin II for 4 weeks caused hypertrophic changes of vascular smooth muscle and cardiomyocytes in rats. Both changes were significantly suppressed by concomitant oral treatment with fasudil, which is metabolized to a specific Rho-kinase inhibitor, hydroxyfasudil, after oral administration. Angiotensin II caused a perivascular accumulation of macrophages and Rho-kinase activation, both of which were also significantly suppressed by fasudil. Vascular NAD(P)H oxidase expression (nox1, nox4, gp91phox, and p22phox) and endothelial production of superoxide anions were markedly increased by angiotensin II, both of which were also significantly suppressed by fasudil. Thus, fasudil ameliorated the impaired endothelium-dependent relaxations caused by angiotensin II without affecting vasodilator function of vascular smooth muscle. These results provide evidence that Rho-kinase is substantially involved in the angiotensin II-induced cardiovascular hypertrophy in rats in vivo. The suppression of endothelial NAD(P)H oxidase upregulation and resultant superoxide production and the amelioration of endothelial vasodilator function may be involved in this process.
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PMID:Long-term inhibition of Rho-kinase suppresses angiotensin II-induced cardiovascular hypertrophy in rats in vivo: effect on endothelial NAD(P)H oxidase system. 1450 Mar 37

Increased production of reactive oxygen species (ROS) is implicated in the development of left ventricular hypertrophy (LVH). Phagocyte-type NADPH oxidases are major cardiovascular sources of ROS, and recent data indicate a pivotal role of a gp91phox-containing NADPH oxidase in angiotensin II (Ang II)-induced LVH. We investigated the role of this oxidase in pressure-overload LVH. gp91phox-/- mice and matched controls underwent chronic Ang II infusion or aortic constriction. Ang II-induced increases in NADPH oxidase activity, atrial natriuretic factor (ANF) expression, and cardiac mass were inhibited in gp91phox-/- mice, whereas aortic constriction-induced increases in cardiac mass and ANF expression were not inhibited. However, aortic constriction increased cardiac NADPH oxidase activity in both gp91phox-/- and wild-type mice. Myocardial expression of an alternative gp91phox isoform, Nox4, was upregulated after aortic constriction in gp91phox-/- mice. The antioxidant, N-acetyl-cysteine, inhibited pressure-overload-induced LVH in both gp91phox-/- and wild-type mice. These data suggest a differential response of the cardiac Nox isoforms, gp91phox and Nox4, to Ang II versus pressure overload.
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PMID:Contrasting roles of NADPH oxidase isoforms in pressure-overload versus angiotensin II-induced cardiac hypertrophy. 1455 Dec 38

Angiotensin II is known to stimulate NADPH oxidase-dependent superoxide (O2-) generation, which may contribute to the acute renal vasoconstrictor and antinatriuretic actions of this peptide. To evaluate this hypothesis, the effects of a superoxide dismutase mimetic (tempol) or a NADPH inhibitor (apocynin) on the angiotensin renal actions were studied. Renal cortical nitric oxide (NO) was measured electrochemically in vivo. Tempol increased sodium excretion and NO levels. Apocynin raised renal blood flow, glomerular filtration rate, sodium excretion, and NO levels. These results indicate the presence of an endogenous NADPH oxidase-dependent O2- generation that may modulate renal function by scavenging NO. Angiotensin II infusion reduced renal blood flow, glomerular filtration, sodium excretion, and NO levels in a dose-dependent manner. The angiotensin receptor antagonist valsartan, tempol, or apocynin blunted the angiotensin effects on renal excretion and NO, suggesting that angiotensin receptors stimulation induces the NADPH oxidase-dependent O2- generation that might reduce NO bioavailability. This idea is supported by the finding that angiotensin increased O2- generation in renal homogenates, and this effect was prevented by valsartan, apocynin, or tempol. These results indicate that some of the acute renal effects of angiotensin II may be enhanced by an increased NADPH oxidase-derived O2- production that reduces renal NO bioavailability.
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PMID:Role of superoxide in modulating the renal effects of angiotensin II. 1459 45


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