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)

The vacuoles of morula cells (MC) of the colonial ascidian Botryllus schlosseri contain phenoloxidase (PO). As the release of their vacuolar content at the border of incompatible contacting colonies is associated with the formation of necrotic masses which characterize the rejection reaction, the role of PO in Botryllus cytotoxicity was investigated. When hemocytes are incubated with blood plasma from incompatible (heterologous) colonies, MC degranulate and, after 60 min, the cytotoxicity index becomes significantly greater than that observed in controls incubated with autologous plasma. The rise in cell mortality is completely inhibited by the addition of PO inhibitors sodium benzoate, tropolone and phenylthiourea, and serine protease inhibitors phenylmethylsulfonyl fluoride, benzamidine, N-tosyl-L-phenylalanine chloromethyl ketone and N-tosyl-L-lysine chloromethyl ketone. The addition of either reducing agents L-cysteine and ascorbic acid or reactive oxygen species scavenger enzymes superoxide dismutase and catalase has a similar effect. Significant inhibition of cytotoxicity is also observed with the quinone scavenger, 3-methyl-2-benzothiazolinone hydrazone. In the presence of sodium benzoate and phenylthiourea, there is a significant reduction in the number, size and color intensity of necrotic masses along the contact border of incompatible colonies. A significant increase in superoxide anion production, completely inhibited by sodium benzoate, is observed when hemocytes are incubated with heterologous blood plasma. These results indicate that: (i) PO is the enzyme responsible for the cytotoxicity observed in both hemocyte cultures and rejection reactions; (ii) PO is present inside MC vacuoles as a proenzyme which is activated, upon release, by humoral proteases; (iii) cytotoxicity appears to be mainly due to oxidative stress generated by PO during oxidation of polyphenols to quinones without the involvement of other oxidases such as NADPH oxidase and peroxidase.
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PMID:Phenoloxidase and cytotoxicity in the compound ascidian Botryllus schlosseri. 987 31

Diphenyleneiodonium (DPI) has frequently been used to inhibit reactive oxygen species (ROS) production mediated by flavoenzymes, particularly NAD(P)H oxidase. This study was undertaken to examine if DPI could also inhibit production of superoxide and H2O2 by mitochondria, the major source of cellular ROS. Detection of mitochondrial superoxide by lucigenin-derived chemiluminescence (CL) with unstimulated monocytes/macrophages showed that DPI at concentrations that inhibit NAD(P)H oxidase markedly diminished the production of superoxide by mitochondrial respiration. Similarly, the extracellular H2O2 derived from mitochondrial respiration as detected by luminol-derived CL in the presence of horseradish peroxidase was also greatly reduced by DPI. DPI was as potent as rotenone in inhibiting the production of superoxide and H2O2 by mitochondrial respiration. With substrate-supported isolated mitochondria, DPI was shown to reduce mitochondrial superoxide production probably through inhibiting NADH-ubiquinone oxidoreductase (complex I).
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PMID:Diphenyleneiodonium, an NAD(P)H oxidase inhibitor, also potently inhibits mitochondrial reactive oxygen species production. 987 31

Our previous results have shown that oxidative stress may reduce the regeneration potential of protoplasts, but only protoplasts that are able to supply extracellularly H(2)O(2) can actually divide (C.I. Siminis, A.K. Kanellis, K.A. Roubelakis-Angelakis [1993] Physiol Plant 87: 263-270; C.I. Siminis, A.K. Kanellis, K.A. Roubelakis-Angelakis [1994] Plant Physiol 1105: 1375-1383; A. de Marco, K.A. Roubelakis-Angelakis [1996a] Plant Physiol 110: 137-145; A. de Marco, K.A. Roubelakis-Angelakis [1996b] J Plant Physiol 149: 109-114). In the present study we have attempted to break down the oxidative burst response into the individual active oxygen species (AOS) superoxide (O(2)(*-)) and H(2)O(2), and into individual AOS-generating systems during the isolation of regenerating tobacco (Nicotiana tabacum L.) and non-regenerating grape (Vitis vinifera L. ) mesophyll protoplasts. Wounding leaf tissue or applying purified cellulase did not elicit AOS production. However, the application of non-purified cellulase during maceration induced a burst of O(2)(*-) and H(2)O(2) accumulation in tobacco leaf, while in grape significantly lower levels of both AOS accumulated. AOS were also generated when protoplasts isolated with purified cellulase were treated with non-purified cellulase. The response was rapid: after 5 min, AOS began to accumulate in the culture medium, with significant quantitative differences between the two species. In tobacco protoplasts and plasma membrane vesicles, two different AOS synthase activities were revealed, one that showed specificity to NADPH and sensitivity to diphenyleneiodonium (DPI) and was responsible for O(2)(*-) production, and a second NAD(P)H activity that was sensitive to KCN and NaN(3), contributing to the production of both AOS. The first activity probably corresponds to a mammalian-like NADPH oxidase and the second to a NAD(P)H oxidase-peroxidase. In grape, only one AOS-generating activity was detected, which corresponded to a NAD(P)H oxidase-peroxidase responsible for the generation of both AOS.
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PMID:The generation of active oxygen species differs in tobacco and grapevine mesophyll protoplasts. 1048 75

The origin of the oxidative burst during plant-pathogen interactions remains controversial. A number of possibilities have been identified, which involve the protoplast, plasmalemma or apoplast. The apoplastic production of H2O2 requires three components, an extracellular peroxidase, ion fluxes leading to extracellular alkalinisation and release of a substrate. Fatty acids are the major compounds that appear in the apoplast following elicitation, which can activate H2O2 production by peroxidases in vitro. However, the reaction with peroxidases appears to be novel and is uncharacterised at present. The apoplastic mechanism also cannot be readily distinguished from the operation of a plasma membrane NADPH oxidase system by the use of the inhibitors diphenylene iodonium and N,N diethyl-dithiocarbamate since it is also inhibited by these. These inhibitors have often in the past been used to define the involvement of the latter in the oxidative burst. In common with the NADPH oxidase system, the peroxidase responsible has been cloned but unlike the NADPH oxidase it has been shown to function in vitro to generate H2O2. In vivo studies of the oxidative burst have shown that the alkalinisation is essential and the underlying ion fluxes may be regulated by cAMP. Calcium fluxes are also essential. Although the oxidative activity of peroxidase requires calcium the fluxes have obvious other function. These may include activation of release of substrate and through the activation of a CDPK, regulation of enzymes involved in phytoalexin and cell wall phenolic production such as PAL.
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PMID:Recent advances in understanding the origin of the apoplastic oxidative burst in plant cells. 1069 52

The properties of the enzymatic system responsible for generating H2O2/O2- in the lignifying xylem of Zinnia elegans were studied using the starch/KI method for monitoring H2O2 production and the nitroblue tetrazolium method for monitoring superoxide anion production. The results showed that H2O2/O2- production by lignifying xylem tissues was insensitive to inhibitors of peroxidase and poly(di)amine oxidases. However, H2O2/O2 production in the xylem of Z. elegans was sensitive to the inhibitors of phagocytic plasma membrane NADPH oxidase, pyridine, imidazole, quinacrine and diphenylene iodonium. The sensitivity of H2O2/O2- production to the respective inhibitors of calmodulin (R-24571), phospholipase C (neomycin sulfate), and protein kinase (staurosporine), and its reversion by an inhibitor of protein phosphatases (cantharidin); pointed to the analogies existing between the mechanism of H2O2/O2- production in the lignifying xylem of Z. elegans and the oxidative burst observed during the hypersensitive plant cell response. These results suggest the existence of a metabolic cascade involving calmodulin, IP3 and protein phosphorylation in the activation of the enzymatic system responsible for H2O2/O2- production in the lignifying xylem of Z. elegans.
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PMID:Some properties of the H2O2/O2- generating system from the lignifying xylem of Zinnia elegans. 1069 53

After deendothelialization, the most luminal smooth muscle cells of the neointima are in contact with blood flow and express inducible nitric oxide synthase (iNOS) in vivo. We hypothesized that shear stress may be a stimulus for this iNOS overexpression. We have thus submitted smooth muscle cells to laminar shear and measured the iNOS expression. Shear stress (20 dyn/cm(2)) induced iNOS mRNA and protein expression, whereas brain NOS mRNA expression was decreased. Conversely, nitrite production was increased. This production was blocked by a selective iNOS inhibitor. Pyrrolidine dithiocarbamate, an antioxidant molecule, and BXT-51072, a gluthation peroxidase mimic, both inhibited the shear-induced iNOS expression. Shear stress also increased the expression of both membrane subunits of NADPH oxidase p22(phox) and Mox-1. Shear stress activated the redox-sensitive nuclear translocation of the transcription nuclear factor-kappaB (NF-kappaB) and stimulated the degradation of both cytosolic inhibitors kappaB alpha and beta. These results show that shear stress can induce iNOS expression and nitrite production in smooth muscle cells and suggest that this regulation is probably mediated by oxidative stress-induced NF-kappaB activation.
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PMID:Shear stress induces iNOS expression in cultured smooth muscle cells: role of oxidative stress. 1107 3

Recognition of avirulent microbial pathogens activates an oxidative burst leading to the accumulation of reactive oxygen intermediates (ROIs), which are thought to integrate a diverse set of defence mechanisms resulting in the establishment of plant disease resistance. A novel transgenic Arabidopsis line containing a gst1:luc transgene was developed and employed to report the temporal and spatial dynamics of ROI accumulation and cognate redox signalling in response to attempted infection by avirulent strains of Pseudomonas syringae pv. tomato (Pst). Strong engagement of the oxidative burst was dependent on the presence of functional Pst hrpS and hrpA gene products. Experiments employing pharmacological agents suggested that at least two distinct sources, including an NADPH oxidase and a peroxidase-type enzyme, contributed to the generation of redox cues. The analysis of gst1 and pal1 gene expression in nahG, coi1 and etr1 plants suggested that engagement of the oxidative burst and cognate redox signalling functioned independently of salicylic acid, methyl jasmonate and ethylene. In contrast, studies using a panel of protein kinase and phosphatase inhibitors and in-gel kinase assays in these mutant backgrounds suggested that a 48 kDa mitogen-activated protein kinase (MAPK) activity was required for the activation of gst1 and pal1 in response to redox cues. Thus the engagement of a bifurcating redox signalling pathway possessing a MAPK module may contribute both to the establishment of plant disease resistance, and to the development of cellular protectant mechanisms.
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PMID:Oxidative burst and cognate redox signalling reported by luciferase imaging: identification of a signal network that functions independently of ethylene, SA and Me-JA but is dependent on MAPKK activity. 1112 96

The nature and origin of the reactive oxygen species (ROS) involved in the early part of Ultraviolet-B (UV-B)-induced signaling pathways were investigated in Arabidopsis thaliana using a range of enzyme inhibitors and free radical scavengers. The increase in PR-1 transcript and decrease in Lhcb transcript in response to UV-B exposure was shown to be mediated through pathways involving hydrogen peroxide (H(2)O(2)) derived from superoxide (O(2)(&z.rad;-)). In contrast, the up-regulation of PDF1.2 transcript was mediated through a pathway involving O(2)(&z.rad;-) directly. The origins of the ROS were also shown to be distinct and to involve NADPH oxidase and peroxidase(s). The up-regulation of Chs by UV-B was not affected by ROS scavengers, but was reduced by inhibitors of nitric oxide synthase (NOS) or NO scavengers. Together these results suggest that UV-B exposure leads to the generation of ROS, from multiple sources, and NO, through increased NOS activity, giving rise to parallel signaling pathways mediating responses of specific genes to UV-B radiation.
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PMID:Early signaling components in ultraviolet-B responses: distinct roles for different reactive oxygen species and nitric oxide. 1116 57

Using the tetrazolium salt XTT (Na,3'-[(phe-nylamino)-carbonyl]-3,4-tetrazolium]-bis(4-methoxy-6-nitro)benzenesulfonic acid hydrate) as a sensitive and physiologically compatible probe for the determination of superoxide (O2*-) production in vivo, we have shown that maize (Zea mays L.) coleoptiles possess the capacity of generating O2*- in the apoplastic space. Our results are in agreement with the notion that this activity is localized at the plasma membrane and can be attributed to an O2*--synthesizing enzyme with catalytic and kinetic properties similar to that of the NADPH oxidase of mammalian phagocytes, with the important exception that it utilizes NADH instead of NADPH as electron donor. When applied to the apoplastic space, NADH strongly increased the O2*--producing activity of coleoptiles. The maize NADH-dependent O2*--synthase activity could clearly be differentiated from peroxidase-mediated O2*--synthesizing activity by its insensitivity to cyanide and azide, as well as by its much higher affinity to O2. Formation of O2*-, and concomitantly appearing H2O2, was preferentially localized in the outer epidermis of the coleoptile. The physiological significance of O2*- and H2O2 production in relation to the growth-controlling function of the epidermal cell wall is discussed.
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PMID:NADH-stimulated, cyanide-resistant superoxide production in maize coleoptiles analyzed with a tetrazolium-based assay. 1121 37

Solanum genotypes that differ in the level of polygenic resistance to the oomycete plant pathogen Phytophthora infestans were studied for their oxidative response to culture filtrate (CF) of the pathogen. Reactive oxygen species (ROS) production, peroxidase activity and lipid peroxidation have been studied in the CF-treated cell suspensions derived from leaves of the resistant S. nigrum (nonhost) and S. tuberosum cv. Bzura as well as from the susceptible S. tuberosum cv. Tarpan and clone H-8105. In both the resistant and susceptible cells the CF induced similar processes, but these varied with respect to the kinetics and intensity. In all cells probably the membrane-bound NADPH oxidase, was responsible for the ROS production. This process was more intensive and prolonged in the susceptible cells than in the resistant ones. The CF treatment slightly affected peroxidase activity in all cells studied. Lipid peroxidation that occurred as a consequence of the ROS accumulation was pronounced mainly in the susceptible cells. We suggest that lack of stringent control of the oxidative processes and sensitivity to the pathogen toxins may be decisive for limited polygenic resistance in potato.
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PMID:The oxidative processes induced in cell suspensions of Solanum species by culture filtrate of Phytophthora infestans. 1137 Oct 14


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