Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.6.3.1 (NADPH oxidase)
 11,281 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Generation of reactive oxygen species (ROS) by Ras oncogene-induced NADPH oxidase (Nox) 1 is required for Ras transformation phenotypes including anchorage-independent growth, morphological transformation, and tumorigenesity, but the signaling mechanism downstream of Nox1 remains elusive. Rho is known to be a critical regulator of actin stress fiber formation. Nonetheless, Rho was reported to no longer couple to loss of actin stress fibers in Ras-transformed Swiss3T3 cells despite the elevation of Rho activity. In this study, however, we demonstrate that Rho is inactivated in K-Ras-transformed normal rat kidney cells, and that abrogation of Nox1-generated ROS by Nox1 small interference RNAs or diphenyleneiodonium restores Rho activation, suggesting that Nox1-generated oxidants mediate down-regulation of the Rho activity. This down-regulation involves oxidative inactivation of the low molecular weight protein-tyrosine phosphatase by Nox1-generated ROS and a subsequent elevation in the tyrosine-phosphorylated active form of p190RhoGAP, the direct target of the phosphatase. Furthermore, the decreased Rho activity leads to disruption of both actin stress fibers and focal adhesions in Ras-transformed cells. As for Rac1, Rac1 also appears to participate in the down-regulation of Rho via Nox1. Our discovery defines a mediating role of Nox1-redox signaling for Ras oncogene-induced actin cytoskeletal changes.
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PMID:Nox1 redox signaling mediates oncogenic Ras-induced disruption of stress fibers and focal adhesions by down-regulating Rho. 1743 18

This study aimed to investigate the effect of the Rho-kinase inhibitor fasudil on the development of diabetic nephropathy and clarify a contribution of the Rho/Rho-kinase pathway to the pathogenesis of diabetic nephropathy. Diabetes was induced in male Sprague-Dawley rats with an intraperitoneal injection of streptozotocin. Animals were then divided into the following 4 groups; normal control rats, diabetic rats, diabetic rats administered fasudil orally and diabetic rats administered fluvastatin (3-hydroxy-methylglutaryl coenzyme A reductase inhibitor, statin) orally. After 1 month of treatment, neither fasudil nor statin had any influence on blood glucose or blood pressure in diabetic rats. While urinary excretion of albumin and 8-hydroxydeoxyguanosine (8-OHdG) was increased in diabetic rats, both of these increases were abolished by fasudil and statin. Rho activity was enhanced in the renal cortex of diabetic rats compared to normal controls, and this enhancement was abolished by statin treatment. Expression of transforming growth factor-beta (TGF-beta) and connective tissue growth factor (CTGF) mRNA was up-regulated in the renal cortex of diabetic rats, and this was abolished by fasudil as well as statin. Expression of NOX4 mRNA (catalytic subunit of NAD(P)H oxidase) was up-regulated in the renal cortex of diabetic rats, an effect which was also abolished by fasudil as well as statin. The present study demonstrates that the Rho/Rho-kinase pathway is involved in up-regulation of TGF-beta, CTGF and NAD(P)H oxidase in diabetic kidney. We conclude that suppression of the Rho/Rho-kinase pathway could be a new strategy for the treatment of diabetic nephropathy.
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PMID:The Rho-kinase inhibitor, fasudil, attenuates diabetic nephropathy in streptozotocin-induced diabetic rats. 1751 84

Cyclooxygenase 2 (COX-2) is induced by microbial products, proinflammatory cytokines, growth factors, and oncogenes. The Rho family includes RhoA, Rac1, Rac2, Rac3, and Cdc42 and is involved in regulation of the actin cytoskeleton organization, cell growth, vesicular cell trafficking, and transcriptional regulation. Rac2 binds to NADPH oxidase protein complex, and Rac2 null neutrophils are known to have poor phagocytic activity. We examined whether Rac2, the predominant small GTPase in hematopoietic cells, influences COX-2 expression in bone marrow-derived macrophages (BMDM). We showed that BMDM from Rac2(-/-) null mice have reduced COX-2 expression in response to treatment with endotoxin. Despite a compensatory increase in Rac1, BMDM from Rac2(-/-) null mice have less biologically active GTP-bound Rac in response to LPS stimulation. Signaling molecules (downstream of Rac2 and Toll-like receptor 4) such as p42/44, p38, and pAKT were also affected in BMDM from Rac2(-/-) null mouse macrophages. We also observed that BMDM from Rac2(-/-) null failed to degrade IkappaBalpha significantly and had less immunoreactive PU.1. We show that both NF-kappaB pathway and PU.1 are involved in normal macrophage function and play a role in macrophage COX-2 expression. In summary, these data indicate that Rac2 regulates COX-2 expression in BMDM.
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PMID:Regulation of cyclooxygenase-2 expression by small GTPase Rac2 in bone marrow macrophages. 1757 12

In the transplant surgery, reactive oxygen species (ROS) from the reperfused tissue cause ischemia-reperfusion injury, resulting in the primary graft failure. We have recently reported that Rho-kinase, an effecter of the small GTPase Rho, plays an important role in the ROS production in the hyperacute phase of reperfusion; however, the sources and mechanisms of the ROS production remain to be elucidated. The aim of this study was to investigate the source of ROS production with a special reference to Rho-kinase to develop a new strategy against ischemia-reperfusion injury. In an in vivo rat model of liver transplantation, Kupffer cells in the graft were depleted using liposome-encapsulated dichloromethylene diphosphonate to examine the source of ROS production. The effect of adenoviral-mediated overexpression of a dominant-negative Rho-kinase (AdDNRhoK) in hepatocytes in the graft was also examined. Kupffer cells were not involved in the ROS production, whereas the AdDNRhoK transfection to hepatocytes significantly suppressed the ROS production. Furthermore, the ROS production was dose-dependently inhibited by apocynin, an NADPH oxidase inhibitor. Expression of DNRhoK also suppressed the release of pro-inflammatory cytokines, and ameliorated the lethal liver injury with a significant prolongation of the survival. These results suggest that the Rho-kinase-mediated pathway plays a crucial role in the ROS production through NADPH oxidase in hepatocytes during the hyperacute phase of reperfusion in vivo. Thus, Rho-kinase in hepatocytes may be a new therapeutic target for the prevention of primary graft failure in liver transplantation.
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PMID:Rho-kinase as a novel gene therapeutic target in treatment of cold ischemia/reperfusion-induced acute lethal liver injury: effect on hepatocellular NADPH oxidase system. 1767 9

Oxidative burst, a critical antimicrobial mechanism of neutrophils, involves the rapid generation and release of reactive oxygen intermediates (ROIs) by the NADPH oxidase complex. Genetic mutations in an NADPH oxidase subunit, gp91 (also referred to as NOX2), are associated with chronic granulomatous disease (CGD), which is characterized by recurrent and life-threatening microbial infections. To combat such infections, ROIs are produced by neutrophils after stimulation by integrin-dependent adhesion to the ECM in conjunction with stimulation from inflammatory mediators, or microbial components containing pathogen-associated molecular patterns. In this report, we provide genetic evidence that both the Vav family of Rho GTPase guanine nucleotide exchange factors (GEFs) and phospholipase C-gamma2 (PLC-gamma2) are critical mediators of adhesion-dependent ROI production by neutrophils in mice. We also demonstrated that Vav was critically required for neutrophil-dependent host defense against systemic infection by Staphylococcus aureus and Pseudomonas aeruginosa, 2 common pathogens associated with fatal cases of hospital-acquired pneumonia. We identified a molecular pathway in which Vav GEFs linked integrin-mediated signaling with PLC-gamma2 activation, release of intracellular Ca2+ cations, and generation of diacylglycerol to control assembly of the NADPH oxidase complex and ROI production by neutrophils. Taken together, our data indicate that integrin-dependent signals generated during neutrophil adhesion contribute to the activation of NADPH oxidase by a variety of distinct effector pathways, all of which require Vav.
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PMID:Neutrophil-mediated oxidative burst and host defense are controlled by a Vav-PLCgamma2 signaling axis in mice. 1793 69

Angiotensin II (Ang II) highly stimulates superoxide anion production by neutrophils. The G-protein Rac2 modulates the activity of NADPH oxidase in response to various stimuli. Here, we describe that Ang II induced both Rac2 translocation from the cytosol to the plasma membrane and Rac2 GTP-binding activity. Furthermore, Clostridium difficile toxin A, an inhibitor of the Rho-GTPases family Rho, Rac and Cdc42, prevented Ang II-elicited O2-/ROS production, phosphorylation of the mitogen-activated protein kinases (MAPKs) p38, extracellular signal-regulated kinase 1/2 (ERK1/2) and c-Jun N-terminal kinase 1/2, and Rac2 activation. Rac2 GTPase inhibition by C. difficile toxin A was accompanied by a robust reduction of the cytosolic Ca(2)(+) elevation induced by Ang II in human neutrophils. Furthermore, SB203580 and PD098059 act as inhibitors of p38MAPK and ERK1/2 respectively, wortmannin, an inhibitor of phosphatidylinositol-3-kinase, and cyclosporin A, a calcineurin inhibitor, hindered both translocation of Rac2 from the cytosol to the plasma membrane and enhancement of Rac2 GTP-binding elicited by Ang II. These results provide evidence that the activation of Rac2 by Ang II is exerted through multiple signalling pathways, involving Ca(2)(+)/calcineurin and protein kinases, the elucidation of which should be insightful in the design of new therapies aimed at reversing the inflammation of vessel walls found in a number of cardiovascular diseases.
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PMID:Rac2 GTPase activation by angiotensin II is modulated by Ca2+/calcineurin and mitogen-activated protein kinases in human neutrophils. 1797 62

Inorganic arsenic is an immunotoxic environmental contaminant to which millions of humans are chronically exposed. We recently demonstrated that human primary macrophages constituted a critical target for arsenic trioxide (As(2)O(3)), an inorganic trivalent form. To specify the effects of arsenic on macrophage phenotype, we investigated in the present study whether As(2)O(3) could regulate the activity of NADPH oxidase, a major superoxide-generating enzymatic system in human phagocytes. Our results show that superoxide levels were significantly increased in a time-dependent manner in blood monocyte-derived macrophages treated with 1 muM As(2)O(3) for 72 h. Concomitantly, As(2)O(3) induced phosphorylation and membrane translocation of the NADPH oxidase subunit p47(phox) and it also increased translocation of Rac1 and p67(phox). Apocynin, a selective inhibitor of NADPH oxidases, prevented both p47(phox) translocation and superoxide production. NADPH oxidase activation was preceded by phosphorylation of p38-kinase in As(2)O(3)-treated macrophages. The p38-kinase inhibitor SB-203580 prevented phosphorylation and translocation of p47(phox) and subsequent superoxide production. Pretreatment of macrophages with the Rho-kinase inhibitor Y-27632 was found to mimic inhibitory effects of SB-203580 and to prevent As(2)O(3)-induced phosphorylation of p38 kinase. Treatment with As(2)O(3) also resulted in an increased secretion of the proinflammatory chemokine CCL18 that was fully inhibited by both apocynin and SB-203580. Taken together, our results demonstrate that As(2)O(3) induced a marked activation of NADPH oxidase in human macrophages, likely through stimulation of a Rho-kinase/p38-kinase pathway, and which may contribute to some of the deleterious effects of inorganic arsenic on macrophage phenotype.
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PMID:Inorganic arsenic activates reduced NADPH oxidase in human primary macrophages through a Rho kinase/p38 kinase pathway. 1842 21

Rac plays a pivotal role in the assembly of the superoxide-generating NADPH oxidase of phagocytes. In resting cells, Rac is found in the cytosol in complex with Rho GDP dissociation inhibitor (RhoGDI). NADPH oxidase assembly involves dissociation of the Rac.RhoGDI complex and translocation of Rac to the membrane. We reported that liposomes containing high concentrations of monovalent anionic phospholipids cause Rac.RhoGDI complex dissociation ( Ugolev, Y., Molshanski-Mor, S., Weinbaum, C., and Pick, E. (2006) J. Biol. Chem. 281, 19204-19219 ). We now designed an in vitro model mimicking membrane phospholipid remodeling during phagocyte stimulation in vivo. We showed that liposomes of "resting cell membrane" composition (less than 20 mol % monovalent anionic phospholipids), supplemented with 1 mol % of polyvalent anionic phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4,5)P(3)) in conjunction with constitutively active forms of the guanine nucleotide exchange factors (GEFs) for Rac, Trio, or Tiam1 and a non-hydrolyzable GTP analogue, cause dissociation of Rac1(GDP).RhoGDI complexes, GDP to GTP exchange on Rac1, and binding of Rac1(GTP) to the liposomes. Complexes were not dissociated in the absence of GEF and GTP, and optimal dissociation required the presence of PtdIns(3,4,5)P(3) in the liposomes. Dissociation of Rac1(GDP).RhoGDI complexes was correlated with the affinity of particular GEF constructs, via the N-terminal pleckstrin homology domain, for PtdIns(3,4,5)P(3) and involved GEF-mediated GDP to GTP exchange on Rac1. Phagocyte membranes enriched in PtdIns(3,4,5)P(3) responded by NADPH oxidase activation upon exposure in vitro to Rac1(GDP).RhoGDI complexes, p67(phox), GTP, and Rac GEF constructs with affinity for PtdIns(3,4,5)P(3) at a level superior to that of native membranes.
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PMID:Dissociation of Rac1(GDP).RhoGDI complexes by the cooperative action of anionic liposomes containing phosphatidylinositol 3,4,5-trisphosphate, Rac guanine nucleotide exchange factor, and GTP. 1850 30

Diminished bioavailability of nitric oxide is a hallmark of endothelial dysfunction and is associated with a broad spectrum of vascular disorders such as impaired angiogenesis. Because Rac1, a Rho family member, mediates cellular motility and generation of reactive oxygen species, it could be involved in the regulation of endothelial nitric oxide production. However, the pathophysiological consequences of postnatal endothelial Rac1 deletion on endothelial function have not been determined. We generated endothelial-specific Rac1 haploinsufficient mice (EC-Rac1(+/-)) using Cre-loxP technology. The EC-Rac1(+/-) mice have decreased expression and activity of endothelial nitric oxide synthase (eNOS), impaired endothelium-dependent vasorelaxation, and mild hypertension compared with control (Rac1(+/flox)) mice. Hind limb ischemia model and aortic capillary sprouting assay showed that eNOS activity and angiogenesis was impaired in EC-Rac1(+/-) mice. Indeed, Rac1 promotes eNOS gene transcription through p21-activated kinase but not NADPH oxidase, increases eNOS mRNA stability, and enhances eNOS activity by promoting endothelial uptake of l-arginine. These findings indicate that endothelial Rac1 is essential for endothelium-dependent vasomotor response and ischemia-induced angiogenesis. These effects of Rac1 on endothelial function are largely due to the upregulation of eNOS through multiple mechanisms that are mediated, in part, by p21-activated kinase. Therapeutic strategies to enhance Rac1 function, therefore, may be important for preventing endothelial dysfunction.
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PMID:Regulation of endothelial nitric oxide synthase and postnatal angiogenesis by Rac1. 1870 82

The statins, hydroxy-3-methylglutaryl-CoA reductase inhibitors that lower serum cholesterol, exhibit myriad clinical benefits, including enhanced vascular integrity. One potential mechanism underlying increased endothelial cell (EC) barrier function is inhibition of geranylgeranylation, a covalent modification enabling translocation of the small GTPases Rho and Rac to the cell membrane. While RhoA inhibition attenuates actin stress fiber formation and promotes EC barrier function, Rac1 inhibition at the cell membrane potentially prevents activation of NADPH oxidase and subsequent generation of superoxides known to induce barrier disruption. We examined the relative regulatory effects of simvastatin on RhoA, Rac1, and NADPH oxidase activities in the context of human pulmonary artery EC barrier protection. Confluent EC treated with simvastatin demonstrated significantly decreased thrombin-induced FITC-dextran permeability, a reflection of vascular integrity, which was linked temporally to simvastatin-mediated actin cytoskeletal rearrangement. Compared with Rho inhibition alone (Y-27632), simvastatin afforded additional protection against thrombin-mediated barrier dysfunction and attenuated LPS-induced EC permeability and superoxide generation. Statin-mediated inhibition of both Rac translocation to the cell membrane and superoxide production were attenuated by geranylgeranyl pyrophosphate (GGPP), indicating that these effects are due to geranylgeranylation inhibition. Finally, thrombin-induced EC permeability was modestly attenuated by reduced Rac1 expression (small interfering RNA), whereas these effects were made more pronounced by simvastatin pretreatment. Together, these data suggest EC barrier protection by simvastatin is due to dual inhibitory effects on RhoA and Rac1 as well as the attenuation of superoxide generation by EC NADPH oxidase and contribute to the molecular mechanistic understanding of the modulation of EC barrier properties by simvastatin.
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PMID:Endothelial cell barrier protection by simvastatin: GTPase regulation and NADPH oxidase inhibition. 1865 77


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