Dissertations / Theses on the topic 'NADPH oxidase (Nox) family'

Kaposi's sarcoma (KS), caused by the oncogenic Kaposi's sarcoma herpesvirus (KSHV), is an angiogenic tumor characterized by intense angiogenesis, inflammation and proliferation of KSHV-infected spindle cells. We describe the characterization of a mouse model of KS by transfection of a KSHV bacterial artificial chromosome (KSHVBac36) into mouse bone marrow endothelial-lineage cells which generated a cell (mECK36) that forms KS-like tumors in mice. Our results define mECK36 as a biologically sensitive animal model of KSHV-dependent KS with the following characteristics: (1) the pathological phenotype is a consequence of KSHV gene expression in normal progenitor cells subjected to in vivo growth conditions, (2) the histopathologic phenotype of the tumors resembles KS lesions, and (3) the model is suitable for analysis of vGPCR-driven tumorigenesis in the context of the whole KSHV genome. The mechanism by which vGPCR promotes tumorigenesis is not fully understood. The characterization of a Rac1 transgenic mouse model that produces KS-like lesions that highly resemble human KS has helped us to identify the potential role of Rac1, which is activated by vGPCR, in the pathogenesis of KS. The results from the RacCA transgenic mouse suggest that viral and host genes triggering Rac1 and ROS production may play an important role in KS tumorigenesis. We set out to determine how vGPCR physiologically activates Rac1 in KSHV-infected cells in the KS model mECK36. We found that KSHV oncogenesis in mECK36 is promoted by vGPCR activation of a paracrine oncogenic mechanism through PDGF-BB, which requires a Rac1- and ROS-mediated loop, leading to STAT3 transcriptional activation of c-Myc, VEGF and KSHV latent viral gene expression. We also found that the latency-associated nuclear antigen (LANA) upregulates the PDGFR in vivo, priming latently-infected cells to the PDGF signaling pathway. This oncogenic mechanism can be targeted with the antioxidant N-acetylcysteine (NAC) and FDA-approved PDGF receptor inhibitors to control KSHV-induced tumorigenesis. Our results highlight a ROS-dependent axis whereby Rac1 activating oncogenes and inflammatory signaling drive paracrine stimulation of neoplastic growth and angiogenesis in neighboring cells, defining this axis and its components as attractive anti-tumor targets in KS pathogenesis.

Atherosclerosis is a complex inflammation condition involving the accumulation of lipid-filled macrophages within the artery wall. Progression of the initial fatty streak to an advanced atherosclerotic plaque is characterized by the development of a necrotic core region containing cholesterol and dead cells. The oxidation of low-density lipoprotein (LDL) to oxidized LDL (oxLDL) and its subsequent uptake by macrophages to form foam cells are the key process in plaque formation. OxLDL is found within atherosclerotic plaque, and it is cytotoxic to a range of cells including macrophages through the generation of reactive oxygen species (ROS) and induction of oxidative stress. The aim of this study was to examine the cytotoxic effects of oxLDL to U937 human monocyte-like cells. OxLDL caused a rapid concentration-dependent cell viability loss in U937 cells within 6 hours. The progression of oxLDL-induced cell death was found to be strongly correlated with the intracellular ROS production and intracellular glutathione (GSH) loss. OxLDL also caused a rapid loss of intracellular aconitase activity, indicating the impairment of the cellular metabolic function. The cytosolic calcium ion (Ca²⁺) level was also elevated by oxLDL, which could be from both intra- and extra-cellular sources. OxLDL also activated plasma membrane superoxide generation complex NADPH oxidase (NOX), and the progression of oxLDL-induced NOX activation was correlated with oxLDL-mediated ROS production, suggesting NOX is the major source of ROS. Further investigations using NOX inhibitors apocynin or diphenyleneiodonium (DPI) found that inhibition of NOX prevented oxLDL-induced cell viability loss, ROS production, GSH loss and aconitase activity decrease. The cytosolic Ca²⁺ elevation caused by oxLDL was also suppressed slightly by inhibiting NOX activity. These results clearly show that NOX is the major site of oxidative stress upon oxLDL activation, contributing to the oxLDL-induced cell death. This study also examined the protective effect of 7,8-dihydroneopterin (7,8-NP) on oxLDL-induced oxidative stress. 7,8-NP dramatically protected cells from oxLDL-induced cell viability loss, ROS generation and aconitase activity loss. 7,8-NP also inhibited oxLDL-induced cytosolic Ca²⁺ influx particularly after 3 hours. 7,8-NP did not inhibited mitochondrial aconitase activity decrease caused by oxLDL, nor inhibited mitochondrial ROS production. This indicates the protective effect of 7,8-NP against oxLDL damage could primarily in cytoplasm. The failure of 7,8-NP protection from oxLDL activating NOX suggests that the protection of 7,8-NP against oxLDL-induced oxidative stress was not due to the inhibition of NOX activation, but by radical scavenging activity of the NOX products.

La NADPH oxydase du phagocyte est une enzyme impliquée dans la défense immunitaire contre les pathogènes. Après activation du phagocyte, cette enzyme produit des ions superoxyde par réduction du dioxygène par le NADPH. Elle est constituée de quatre sous- unités cytosolubles (p47phox ; p67phox ; p40phox et Rac), et deux membranaires (gp91 ; p22phox). Son activation fait intervenir un processus complexe qui met en jeu des changements d’interaction entre les protéines la constituant et qui permet l’assemblage des six sous- unités. Afin d’obtenir des informations sur les processus d’assemblage et d’activation, j’ai reconstitué le complexe dans un système cell free à l’aide de protéines recombinantes pour pouvoir contrôler tous les paramètres. Dans ce travail nous avons comparé les modes d’activation de p47phox par phosphorylation, par mutation substitutionelle sérine - aspartate en position S303,S304 et S328 pour mimer la phosphorylation et enfin par addition d’acide arachidonique (AA) activateur connu de l’enzyme in vitro mais aussi in vivo. Bien qu’il ai été montré que ces trois méthodes ouvrent la protéine vers une conformation ayant des propriétés similaires, nous avons trouvé que les effets de ces méthodes d’activation sont significativement différents. Ainsi, les changement de conformation observés par dichroisme circulaire, sont dissemblables. Pour p47phox, l’addition de AA déstructure la protéine. La phosphorylation induit un déplacement bathochrome des bandes de CD qualitativement similaire, alors que les mutations S-D de p47phox provoquent un déplacement opposé. Pour le complexe p47phox-p67phox l’addition d’AA destructure le mélange tandis que la mutation induit relativement peu de changement. Nous avons mesuré les constantes de dissociation Kd du complexe p47phox-p67phox. Alors que pour les protéines « sauvages », le Kd est faible (4±2 nM), les mutations de p47phox ainsi que l’addition d’AA augmentent cette valeur jusqu’à environ 50 nM, montrant une diminution de l’affinité entre p47phox-p67phox. De même, sur le complexe entier, l’effet de la phosphorylation de p47phox est différent de la mutation. Nous avons mesuré les valeurs de EC50 relatives à p67phox pour les différentes formes de p47phox. L’activation de p47phox par phosphorylation diminue l’EC₅₀, alors que les doubles ou triple mutations augmentent sa valeur. Nous avons confirmé que la phosphorylation et la mutation sont insuffisantes pour activer l’enzyme. La présence de AA est indispensable pour le fonctionnement du complexe. L’ordre de fixation des sous unités cytosoliques semble indifférent mais il faut que tous les composants soient présents lors de l’ajout de AA. Enfin, la délétion de p47phox dans la partie C-terminale (aa 343 à 390, domaine d’interaction avec p67phox) il n’y a plus de formation du dimère mais l’enzyme fonctionne normalement. Ces résultats apportent des éléments nouveaux sur le rôle de la dimérisation p47 phox-p67 phox, non indispensable à l’activité du système et sur le rôle mineur de la phosphorylation dans l’activation de la NADPH oxydase in vitro
The NADPH oxidase of phagocytes is an enzyme involved in the innate defense of organisms against pathogens. After phagocyte activation, this enzyme produces superoxide ions by reduction of dioxygen by NADPH. It is constituted of four cytosolic sub-units (p47phox ; p67phox ; p40phox et Rac) and two membrane proteins (gp91 ; p22phox). Its activation takes place through a complex process that involves protein-protein interaction changes leading to assembly and functionning of the catalytic core. In order to obtain information on this process, I have reconstituted the enzyme in a cell free systeme using recombinant proteins, to be able to fully control all the measurement conditions. In this work, we have compared different activation modes of p47phox i) phosphorylation; ii) substitution serine - aspartate by mutations at positions S303, S304 and S328 to mimic phosphorylation; iii) addition of arachidonic acid (AA), a well known activator molecule in vitro. It has been shown that these three activating methods transform p47phox to an open configuration with similar characteristics. However, we have found that the effects of these methods are significantly different. Indeed, the conformational changes observed by circular dichroism are different. For p47phox, the addition of AA destructures the protein. Its phosphorylation induces a bathochromic displacement of the bands, whereas the mutations S-D lead to an opposite displacement. For the dimer p47phox-p67phox , the addition of AA destructures the proteins while mutations induce hardly no changes. We have measured the dissociation constant Kd of the complex p47phox-p67phox. For wild type proteins, Kd value is low (4±2 nM), while mutations of p47phox as well as addition of AA increase its value up to 50 nM, showing a decrease of affinity between p47phox and p67phox. Moreover, on the whole complex, the effect of phosphorylation of p47phox is different from mutations. We have shown that the EC50 values relative to p67phox are sensitive to the various modifications of p47phox. Phosphorylation of p47phox decreases EC₅₀, while double or triple mutations increase its value. We have confirmed that phosphorylation and mutation are not sufficient to activate the enzyme. The presence of AA is a prerequisite for the functionning of the complex, i.e. production of superoxide. The binding order of the cytosolic proteins seems random but it is necessary that all the components be present during the activation by AA. Finally, deletion of the C terminal part of p47phox (aa 343 to 390, interaction domain with p67phox) leads to the absence of dimer formation but does not affect the enzyme activity. These results bring new information on the role of dimerisation of p47-p67 and on that of phosphorylation in the activation of NADPH oxidase in vitro

Les NADPH oxydases constituent une famille d'enzymes dont la fonction est dédiée à la production de formes réactives de l'oxygène. NOX1, un des membres de cette famille, est abondamment exprimée dans le colon et sa dérégulation pourrait être associée aux maladies inflammatoires chroniques de l'intestin. Les mécanismes qui modulent l'activation de NOX1 demeurent mal connus. Au cours de ma thèse je me suis donc intéressée à l'étude de la phosphorylation de NOXA1 et NOXO1, deux sous-unités régulatrices du complexe NOX1 et ai démontré 1) que la phosphorylation de NOXA1 constitue un mécanisme de régulation négative de l'activité de NOX1 en vue de maintenir l'activité constitutive du complexe à un niveau adéquat et non excessif. 2) pour la première fois, que NOXO1β est phosphorylée et que cette phosphorylation entraîne une hyperactivation de NOX1. L'ensemble de ces données montre que NOX1 est finement régulée. Par ce biais, NOX1 pourrait être impliquée dans la défense anti-infectieuse de l'intestin.

Aortic dissection is a detrimental disease with a high mortality. However, the mechanisms regulating the susceptibility to aortic dissection remain unknown. We hypothesize that endothelial oxidative stress due to the activation of the reactive oxygen species (ROS)-generating Nox2 enzyme may play an important role in the development of aortic dissection. To investigate this, we generated transgenic mice (C57BL/6J background) with endothelial specific over-expression of Nox2 (Nox2 Tg) under the control of a tie-2 promoter. Expression of the human Nox2 transgene was confirmed by qRT-PCR to be found only in endothelial cells (EC) isolated from transgenic mice, and not in Wt EC or vascular smooth muscle cells (VSMC) and macrophages isolated from either genotype. Wild-type (Wt) littermates and Nox2 Tg male mice (22-24 weeks old, n=11) were treated with saline or Ang II (1mg/kg/day) via subcutaneous mini-pump for 28 days. There was no significant difference in the pressor responses to Ang II between Wt and Nox2 Tg mice (Wt 121±7mmHg vs. Nox2-Tg 122±6mmHg). However, 5/11 Nox2 Tg mice developed aortic dissections compared to 0/11 Wt mice (P<0.05). Immunohistochemistry revealed significant increases in endothelial VCAM-1 expression, MMP activity and CD45+ inflammatory cell recruitment in the aortas of Nox2 Tg mice after 5 days of Ang II infusion. Inflammatory cell recruitment was confirmed by FACS analysis of cells from digested aortas (P<0.05). Explanted aortas from Nox2-Tg mice had significantly greater secreted pro-inflammatory cytokine, Cyclophilin A (CypA) both at baseline and after 5 days of Ang II infusion compared to Wt littermates. Compared to primary Wt EC and VSMC, Nox2-Tg primary EC, but not primary VSMC, had increased ROS production which was accompanied by increased endothelial CypA secretion and ERK1/2 activation. Furthermore, conditioned media from Nox2-Tg EC induced greater ERK1/2 phosphorylation compared to conditioned media from Wt controls. Knockdown of CypA from sEND.1 endothelial conditioned media by siRNA knockdown abolished VSMC Erk1/2 phosphorylation. In conclusion, we demonstrate for the first time that a specific increase in endothelial ROS through the over-expression of Nox2 was sufficient to induce aortic dissection in response to Ang II stimulation. Endothelial secreted CypA could be the signalling mechanism by which increased endothelial ROS regulates the inflammatory response and the susceptibility to aortic dissection.

Le placenta est un organe transitoire permettant les échanges nutritionnel et gazeux entre la mère et le fœtus. Son unité structurale et fonctionnelle est la villosité choriale (VC), constituée en son centre d'un axe mésenchymateux bordé par une couche cellulaire de cytotrophoblastes villeux (CTV) fusionnant pour former la couche la plus externe : le syncytiotrophoblaste (ST), sécréteur d'hormones indispensables au maintien de la grossesse, notamment l'hCG. Au premier trimestre de la grossesse (T1), le placenta se développe dans un environnement pauvre en O2 dû à l'obstruction des artères utérines spiralées par des bouchons cytotrophoblastiques empêchant le sang maternel oxygéné de pénétrer dans la chambre intervilleuse (CIV). Dès 10 semaines d'aménorrhée (SA), ces bouchons se délitent, laissant entrer le flux sanguin dans la CIV au contact direct du placenta. La pO2 passe alors de 20 mmHg à 60 mmHg. En présence d'O2, la cellule produit des espèces réactives de l'oxygène (ERO) jouant le rôle de seconds messagers dans de multiples processus physiologiques (prolifération, différenciation, apoptose). Ils peuvent être cytotoxiques dans le cas du stress oxydant : la cellule possède un système de défense antioxydant permettant de maintenir le taux d'ERO intracellulaire à un niveau physiologique faible. L'équilibre des espèce pro- et anti-oxydantes est appelé homéostasie redox. Au T1, le placenta est soumis à une transition environnementale requérant l'adaptation de sa balance redox pour assurer le bon développement du placenta. Les objectifs de ce travail sont : (i) Déterminer la source principale d'anion superoxyde O2.- avant et après l'augmentation de la pO2 dans la CIV et étudier les défenses antioxydantes associées. (ii) Etudier l'impact de l'oxygéno-transition sur les voies redox-sensibles, notamment les MAPKs impliquées dans la prolifération et la différentiation trophoblastique. (iii) De déterminer au T1 l'influence de l'activité de la NADPH oxydase (Nox) placentaire sur la sécrétion du sFlt-1, facteur anti-angiogénique impliqué dans la physiopathologie de la prééclampsie (PE) afin de proposer de nouvelles réflexions concernant l'implication de la Nox dans la genèse de cette pathologie d'origine placentaire. Dans la VC (7-9 SA et 12-14 SA), la mesure de la production d'O2.- alliée à l'utilisation d'inhibiteurs spécifiques des différentes sources d'ERO montre que la Nox est la source principale d'O2.- au T1. Cette production est plus importante avant 10 SA et est associée à une modification de la localisation de la sous-unité organisatrice de Nox2, p47phox. Cette activation de la Nox placentaire est associée à une activation de la voie p38MAPK. p38 est localisée essentiellement dans le CTV au T1. L'expression génique et protéique des différentes isoformes de Nox révèle la présence de Nox2, Nox4 et Nox5 dans le trophoblaste au T1. Nox1 est cependant indétectable. L'activité des enzymes antioxydantes (SOD1, catalase, Gpx1) est augmentée à 12-14 SA, témoin de l'adaptation du système antioxydant à l'oxygéno-transition. L'exposition de VC à 7-9 SA au TGF-B1, activateur de Nox4 et de p38MAPK, associée à un inhibiteur de la voie p38 (SB203580), montre que l'activation de la voie p38 par le TGF-B1 entraine une augmentation de la sécrétion de sFlt-1. Cet effet est aboli par l'utilisation de SB203580. Dans notre modèle, l'exposition au TGF-B1 n'influence pas l'activation de la Nox. Cependant, l'utilisation d'un inhibiteur de Nox (DPI) permet de diminuer la sécrétion de sFlt-1. Ce travail a permis de montrer que la Nox est la source principale d'O2.- dans le placenta au premier trimestre en association avec l'activation de la voie p38MAPK. Nos résultats montrent que la sécrétion du sFlt-1 par la VC au premier trimestre est dépendante de la voie p38MAPK. Ce travail permettra une meilleure compréhension de l'implication des sources d'ERO dans le développement placentaire précoce et leur(s) rôle(s) dans la pathogenèse de la PE
The placenta is a transitory organ allowing gas and nutrients exchanges between mother and fetus. The structural and functional unit of the human placenta is the chorionic villi (CV). It is composed by a mesenchymal axis covered with a cellular layer called villous cytotrophoblast (VCT), which merges to form the syncytiotrophoblast (ST). The ST secretes hormones essential to maintain pregnancy, especially hCG. During the first trimester of pregnancy (T1), placenta develops itself in a poor oxygenated environment because of the obstruction of uterine spiraled arteries by cytotrophoblastic plugs which restrain the entry of the oxygenated maternal blood into the intervillous space (IVS). Between 10-12 gestational weeks (GW), the plugs will gradually disappear allowing blood to enter IVS in direct contact with CV. The pO2 will increase from 20 mmHg to 60 mmHg. Exposed to O2, the cell produces reactive oxygen species (ROS). ROS play a role as second messenger in redox-sensitive signaling pathways involved in physiological processes (proliferation, differentiation, apoptosis). They may become cytotoxic when oxidative stress occurs: the cell has an antioxidant defense system responsible for keeping low physiological levels of intracellular ROS, enough to ensure signal transduction. The balance between pro- and antioxidant systems is called redox homeostasis. The first trimester placenta is submitted to an environmental transition requiring redox balance adaptation to allow correct placental development in early pregnancy. The aim of this works are: (i) to determine the principal source of superoxide anion O2.- before and after the increase of pO2 in the intervillous space and the associated antioxidant defenses. (ii) To study the impact of the O2 transition on the activity of redox-sensitive pathways, specifically MAPKs involved in trophoblastic proliferation, differentiation. (iii) To determine, during T1, the placental NADPH oxidase (Nox) activity influence on the secretion of the antiangiogenic factor sFlt-1, which is involved in the pathophysiology of preeclampsia (PE), to offer new insight about Nox involvement in genesis of this pathology with placental origin. We measured the O2.- production in CV (7-9 GW vs. 12-14 GW). The O2.- assay was performed with specific inhibitors of ROS sources. The results show that NADPH oxidase (Nox) is the major source of O2.- in first trimester CV. Nox activity is significantly higher before 10 GW. This is confirmed by the modification of the Nox2 organizer subunit location, p47phox. This Nox activation in early stage of pregnancy is associated with p38 MAPK activation. p38 protein is mainly located within the villous cytotrophoblast in first trimester CV. Genic and protein expression study reveals the expression of Nox2, Nox4 and Nox5 isoforms in T1 trophoblast. Nox1 expression remains undetectable. The antioxidant enzymes (SOD1, catalase, and Gpx1) activities are increased at 12-14 GW, revealing an antioxidant system adaptation to the oxygen transition. We exposed CV from 7 to 9 GW to TGF-B1, described as an activator of Nox4 and p38MAPK, and to p38 inhibitor (SB203580). The results showed that the activation of p38MAPK pathway in first trimester CV by TGF-B1 increases the level of secreted sFlt-1. This effect is abolished using SB203580. TGF-B1 exposure does not influence the activation of placental Nox in our model, but the use of a Nox inhibitor (DPI) decreases the secretion of sFlt-1. To conclude, our work shows that Nox is the main source of O2.- in first trimester placenta and is associated with the activation of the p38MAPK pathway. Our results also demonstrate that first trimester CV sFlt-1 secretion relies on the p38MAPK activation. This work allows a better understanding of the cellular sources of ROS involvement in early placental development and their role in pathogenesis of preeclampsia

Reactive oxygen species (ROS) have a role in cardiovascular health and disease. This study was undertaken to determine if ROS formation is influenced by either common genetic variations in p22phox, a subunit of the ROS generating enzyme NOX1, or by natural plant compounds with cardiovascular benefits. Hydrogen peroxide production was measured using Amplex Red, and superoxide generation was measured using NBT and MCLA. Each of seven p22phox variants supported ROS generation by NOX1. No differences were found in the rate of ROS production; however, unequal transfer of the p22phox gene may be a confounding factor. A variation in the 3’UTR of the p22phox gene led to lower p22phox protein levels, whereas none of the other variations affected mRNA or protein expression. The natural compound resveratrol acts as an antioxidant towards hydrogen peroxide, but not superoxide. Resveratrol does not inhibit NOX1 activity.

Parkinson’s disease (PD) is a progressive neurodegenerative disorder characterized by the selective loss of dopaminergic (DA) neurons in the substantia nigra (SN) pars compacta (SNpc), to which contribute the combination of aging and genetic and environmental factors. Several studies clearly showed an increase in the incidence of PD in rural environments, and hypothesized the involvement of pesticides, like paraquat (PQ), in the mechanisms of neurodegeneration. PQ can be reduced by the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (Nox) enzyme and can induce its toxicity through the production of superoxide anions, which leads to the accumulation of reactive oxygen species (ROS) in the cell. Matsuzaki and its collaborators showed that ROS formation induced by PQ facilitate α-synuclein association, a biochemical hallmark of PD. The Nox system generates ROS in a regulated manner, producing ROS in various tissues. It has been suggested that Nox1 subunit plays a role in plays a role in the oxidative stress and subsequent DA cell death elicited by PQ. Protein kinase C delta (PKCδ) has been showed to be involved in apoptotic signaling pathways, by phosphorylation and activation of several inducers of cell death. PQ induces an increase of ROS production and death of DA neurons. In the present work we aimed to investigate in PQ exposed cells the possible relationship between ROS generation by Nox1 and the putative regulatory effect of PKCδ in the process. To investigate whether PKCδ influences ROS production, DA cell death and Nox1 expression, short interference RNA (siRNA) was used to specifically knockdown PKCδ. Transfection with PKCδ-siRNA decrease mRNA levels by 32% and protein levels by 54%. We observed that ROS and DA cell death induced by PQ were significantly reduced by PKCδ knockdown, in N27 cells transfected with PKCδ-siRNA. This study also revealed that, in DA neurons, the upregulation of Nox1 mRNA and protein induced by PQ exposure is reversed when PKCδ is knockdown, suggesting a possible involvement of PKCδ in the regulation of Nox1 expression pathways affected by PQ.

Parkinson´s Disease (PD) is a chronic progressive neurodegenerative disease; characterized by degeneration of nigrostriatal dopaminergic neurons in the substantia nigra pars compacta (SNpc). Several environmental conditions such as exposure to pesticides like Paraquat (PQ) are considered risk factors for PD. Treatment of animal models with PQ induces changes characteristic of parkinsonism. The cellular toxicity of PQ is, in part, due to its redox cycle of reactions that lead to the generation of reactive oxygen species (ROS), mainly hydrogen peroxide, and hydroxyl radical and to the consequent cellular damage. To cope with the many oxidative reactions, antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) and gluthathione peroxidise are present in cells to balance the oxidative mechanisms Therefore, in order to counteract the oxidative stress, ROS inducers can also trigger an increase of antioxidant enzymes levels. PQ induces its toxic effects on N27 cells by activating the NADPH oxidase (Nox) system, particularly Nox1, which, in turn, generates ROS. Taking in account this data we raise the possibility that dopaminergic Nox1 may be involved in the regulating the expression of antioxidant enzymes. We assessed mRNA levels of SOD and CAT after 1 and 6h exposure to PQ in N27 cells. Protein levels were evaluated after an incubation with PQ during 16 and 24h, with or without the presence of apocynin, an inhibitor of Nox. We also studied SOD and CAT protein levels in the SN of rats exposed to PQ. Stimulation of N27 cells with low concentrations of PQ increased SOD mRNA expression levels, whereas increases of CAT mRNA levels were observed in cells exposed to high concentrations of PQ for 1h. . However, CAT protein levels were increased by incubation, for 24hr, with 1000 μM PQ, and SOD levels were increased by incubation with low concentration of PQ. The increase of both SOD and CAT protein levels induced by PQ was reduced by the in vivo Nox1 silencing, results concordant with the the immunohistochemistry data. In conclusion, with the present study, we demonstrated that PQ increases SOD and CAT expression and that Nox1 may be involved in the regulation of these antioxidant enzymes.