The insert region of the Rac GTPases is dispensable for activation of superoxide-producing NADPH oxidases

2009 ◽  
Vol 422 (2) ◽  
pp. 373-382 ◽  
Author(s):  
Kei Miyano ◽  
Hirofumi Koga ◽  
Reiko Minakami ◽  
Hideki Sumimoto
Keyword(s):  
Amino Acids ◽  
Nadph Oxidase ◽  
Essential Role ◽  
Cellular Level ◽  
Nadph Oxidases ◽  
Catalytic Core ◽  
Rac Gtpases ◽  
Nadph Oxidase 1 ◽  
Nox Family ◽  
Insert Region

Rac1 and Rac2, which belong to the Rho subfamily of Ras-related GTPases, play an essential role in activation of gp91phox/Nox2 (cytochrome b-245, β polypeptide; also known as Cybb), the catalytic core of the superoxide-producing NADPH oxidase in phagocytes. Rac1 also contributes to activation of the non-phagocytic oxidases Nox1 (NADPH oxidase 1) and Nox3 (NADPH oxidase 3), each related closely to gp91phox/Nox2. It has remained controversial whether the insert region of Rac (amino acids 123–135), unique to the Rho subfamily proteins, is involved in gp91phox/Nox2 activation. In the present study we show that removal of the insert region from Rac1 neither affects activation of gp91phox/Nox2, which is reconstituted under cell-free and whole-cell conditions, nor blocks its localization to phagosomes during ingestion of IgG-coated beads by macrophage-like RAW264.7 cells. The insert region of Rac2 is also dispensable for gp91phox/Nox2 activation at the cellular level. Although Rac2, as well as Rac1, is capable of enhancing superoxide production by Nox1 and Nox3, the enhancements by the two GTPases are both independent of the insert region. We also demonstrate that Rac3, a third member of the Rac family in mammals, has an ability to activate the three oxidases and that the activation does not require the insert region. Thus the insert region of the Rac GTPases does not participate in regulation of the Nox family NADPH oxidases.

scholarly journals NADPH oxidase 4 and its role in the cardiovascular system

2019 ◽  
Vol 1 (1) ◽  
pp. H59-H66
Author(s):  
Stephen P Gray ◽  
Ajay M Shah ◽  
Ioannis Smyrnias
Keyword(s):  
Nadph Oxidase ◽  
Cardiovascular System ◽  
Contractile Function ◽  
Cellular Level ◽  
Nadph Oxidases ◽  
Nadph Oxidase 4 ◽  
Specific Effects ◽  
Different Types ◽  
Electron Reduction ◽  
Nox Family

The heart relies on complex mechanisms that provide adequate myocardial oxygen supply in order to maintain its contractile function. At the cellular level, oxygen undergoes one electron reduction to superoxide through the action of different types of oxidases (e.g. xanthine oxidases, uncoupled nitric oxide synthases, NADPH oxidases or NOX). Locally generated oxygen-derived reactive species (ROS) are involved in various signaling pathways including cardiac adaptation to different types of physiological and pathophysiological stresses (e.g. hypoxia or overload). The specific effects of ROS and their regulation by oxidases are dependent on the amount of ROS generated and their specific subcellular localization. The NOX family of NADPH oxidases is a main source of ROS in the heart. Seven distinct Nox isoforms (NOX1–NOX5 and DUOX1 and 2) have been identified, of which NOX1, 2, 4 and 5 have been characterized in the cardiovascular system. For the purposes of this review, we will focus on the effects of NADPH oxidase 4 (NOX4) in the heart.

scholarly journals The NOX Family of ROS-Generating NADPH Oxidases: Physiology and Pathophysiology

2007 ◽  
Vol 87 (1) ◽  
pp. 245-313 ◽  
Author(s):  
Karen Bedard ◽  
Karl-Heinz Krause
Keyword(s):  
Nadph Oxidase ◽  
Regulation Of Gene Expression ◽  
Nadph Oxidases ◽  
Phagocyte Nadph Oxidase ◽  
Current State ◽  
Wide Range ◽  
The Family ◽  
Activation Mechanisms ◽  
Long Time ◽  
Nox Family

For a long time, superoxide generation by an NADPH oxidase was considered as an oddity only found in professional phagocytes. Over the last years, six homologs of the cytochrome subunit of the phagocyte NADPH oxidase were found: NOX1, NOX3, NOX4, NOX5, DUOX1, and DUOX2. Together with the phagocyte NADPH oxidase itself (NOX2/gp91phox), the homologs are now referred to as the NOX family of NADPH oxidases. These enzymes share the capacity to transport electrons across the plasma membrane and to generate superoxide and other downstream reactive oxygen species (ROS). Activation mechanisms and tissue distribution of the different members of the family are markedly different. The physiological functions of NOX family enzymes include host defense, posttranlational processing of proteins, cellular signaling, regulation of gene expression, and cell differentiation. NOX enzymes also contribute to a wide range of pathological processes. NOX deficiency may lead to immunosuppresion, lack of otoconogenesis, or hypothyroidism. Increased NOX actvity also contributes to a large number or pathologies, in particular cardiovascular diseases and neurodegeneration. This review summarizes the current state of knowledge of the functions of NOX enzymes in physiology and pathology.

scholarly journals Tumor Necrosis Factor-α-Induced Colitis Increases NADPH Oxidase 1 Expression, Oxidative Stress, and Neutrophil Recruitment in the Colon: Preventive Effect of Apocynin

2014 ◽  
Vol 2014 ◽  
pp. 1-15 ◽  
Author(s):  
Souad Mouzaoui ◽  
Bahia Djerdjouri ◽  
Nesrine Makhezer ◽  
Yolande Kroviarski ◽  
Jamel El-Benna ◽  
...  
Keyword(s):  
Tumor Necrosis Factor ◽  
Nadph Oxidase ◽  
Tumor Necrosis ◽  
Map Kinases ◽  
Antioxidant Properties ◽  
Oxidase Inhibitor ◽  
Nadph Oxidases ◽  
Nadph Oxidase 1 ◽  
Factor Α ◽  
Necrosis Factor

Reactive oxygen species- (ROS-) mediated injury has been implicated in several inflammatory disorders, including inflammatory bowel disease (IBD). NADPH oxidases (NOXs) are the major source of endogenous ROS. Here, we investigated the role of NOXs derived-ROS in a mouse model of colitis induced by the proinflammatory cytokine, tumor necrosis factor-α(TNF-α). Intraperitoneal injection of TNFα(10 μg · kg−1) induced an acute inflammation of the colon and a marked increase in expression of NADPH oxidase 1 (NOX1), a colon specific NADPH oxidase isoform. TNFα-induced colitis was also characterized by high production of keratinocyte-derived chemokine (KC) and mucosal infiltration of neutrophils, NOX2-expressing cells. Concomitantly, ROS production and lipid peroxidation were significantly enhanced while catalase activity and glutathione level were reduced indicating a redox imbalance in the colon. Furthermore, the redox-sensitive MAP kinases, ERK1/2 and p38 MAPK, were activated during TNFα-induced colitis. Pretreatment of mice with apocynin, an NADPH oxidase inhibitor with antioxidant properties, before TNFαchallenge, prevented all these events. These data suggest that ROS derived from NADPH oxidases (mainly NOX1 and NOX2) and MAP kinase pathways could contribute to the induction and expansion of oxidative lesions characteristics of IBD and that apocynin could potentially be beneficial in IBD treatment.

scholarly journals Activation of the superoxide-producing phagocyte NADPH oxidase requires co-operation between the tandem SH3 domains of p47phox in recognition of a polyproline type II helix and an adjacent α-helix of p22phox

2006 ◽  
Vol 396 (1) ◽  
pp. 183-192 ◽  
Author(s):  
Ikuo Nobuhisa ◽  
Ryu Takeya ◽  
Kenji Ogura ◽  
Noriko Ueno ◽  
Daisuke Kohda ◽  
...  
Keyword(s):  
Amino Acids ◽  
Nadph Oxidase ◽  
Regulatory Protein ◽  
Sh3 Domain ◽  
Alanine Scanning Mutagenesis ◽  
Catalytic Core ◽  
Intact Cells ◽  
Sh3 Domains ◽  
Phagocyte Nadph Oxidase ◽  
Phagocyte Oxidase

Activation of the superoxide-producing phagocyte NADPH oxidase, crucial for host defence, requires an SH3 (Src homology 3)-domain-mediated interaction of the regulatory protein p47phox with p22phox, a subunit of the oxidase catalytic core flavocytochrome b558. Although previous analysis of a crystal structure has demonstrated that the tandem SH3 domains of p47phox sandwich a short PRR (proline-rich region) of p22phox (amino acids 151–160), containing a polyproline II helix, it has remained unknown whether this model is indeed functional in activation of the oxidase. In the present paper we show that the co-operativity between the two SH3 domains of p47phox, as expected from the model, is required for oxidase activation. Deletion of the linker between the p47phox SH3 domains results not only in a defective binding to p22phox but also in a loss of the activity to support superoxide production. The present analysis using alanine-scanning mutagenesis identifies Pro152, Pro156 and Arg158 in the p22phox PRR as residues indispensable for the interaction with p47phox. Pro152 and Pro156 are recognized by the N-terminal SH3 domain, whereas Arg158 contacts with the C-terminal SH3 domain. Amino acid substitution for any of the three residues in the p22phox PRR abrogates the superoxide-producing activity of the oxidase reconstituted in intact cells. The bis-SH3-mediated interaction of p47phox with p22phox thus functions to activate the phagocyte oxidase. Furthermore, we provide evidence that a region C-terminal to the PRR of p22phox (amino acids 161–164), adopting an α-helical conformation, participates in full activation of the phagocyte oxidase by fortifying the association with the p47phox SH3 domains.

scholarly journals Tracing the Trophic Plasticity of the Coral–Dinoflagellate Symbiosis Using Amino Acid Compound-Specific Stable Isotope Analysis

2021 ◽  
Vol 9 (1) ◽  
pp. 182
Author(s):  
Christine Ferrier-Pagès ◽  
Stephane Martinez ◽  
Renaud Grover ◽  
Jonathan Cybulski ◽  
Eli Shemesh ◽  
...  
Keyword(s):  
Amino Acids ◽  
Essential Role ◽  
Isotope Analysis ◽  
Diagnostic Tools ◽  
Global Changes ◽  
Biosynthetic Pathways ◽  
Trophic Plasticity ◽  
Trophic Index ◽  
Δ15n And Δ13c ◽  
Acid Compound

The association between corals and photosynthetic dinoflagellates is one of the most well-known nutritional symbioses, but nowadays it is threatened by global changes. Nutritional exchanges are critical to understanding the performance of this symbiosis under stress conditions. Here, compound-specific δ15N and δ13C values of amino acids (δ15NAA and δ13CAA) were assessed in autotrophic, mixotrophic and heterotrophic holobionts as diagnostic tools to follow nutritional interactions between the partners. Contrary to what was expected, heterotrophy was mainly traced through the δ15N of the symbiont’s amino acids (AAs), suggesting that symbionts directly profit from host heterotrophy. The trophic index (TP) ranged from 1.1 to 2.3 from autotrophic to heterotrophic symbionts. In addition, changes in TP across conditions were more significant in the symbionts than in the host. The similar δ13C-AAs signatures of host and symbionts further suggests that symbiont-derived photosynthates are the main source of carbon for AAs synthesis. Symbionts, therefore, appear to be a key component in the AAs biosynthetic pathways, and might, via this obligatory function, play an essential role in the capacity of corals to withstand environmental stress. These novel findings highlight important aspects of the nutritional exchanges in the coral–dinoflagellates symbiosis. In addition, they feature δ15NAA as a useful tool for studies regarding the nutritional exchanges within the coral–symbiodiniaceae symbiosis.

scholarly journals The role of endothelial interleukin-8/NADPH oxidase 1 axis in sepsis

Immunology ◽  
2010 ◽  
Vol 131 (3) ◽  
pp. 331-339 ◽  
Author(s):  
Takashi Miyoshi ◽  
Kouhei Yamashita ◽  
Toshiyuki Arai ◽  
Kokichi Yamamoto ◽  
Kiyomi Mizugishi ◽  
...  
Keyword(s):  
Nadph Oxidase ◽  
Interleukin 8 ◽  
Nadph Oxidase 1

scholarly journals Simvastatin rescues homocysteine-induced apoptosis of osteocytic MLO-Y4 cells by decreasing the expressions of NADPH oxidase 1 and 2

2016 ◽  
Vol 63 (4) ◽  
pp. 389-395 ◽  
Author(s):  
Ayumu Takeno ◽  
Ippei Kanazawa ◽  
Ken-ichiro Tanaka ◽  
Masakazu Notsu ◽  
Maki Yokomoto-Umakoshi ◽  
...  
Keyword(s):  
Nadph Oxidase ◽  
Nadph Oxidase 1 ◽  
Induced Apoptosis

scholarly journals Characterization of the 6'-N-aminoglycoside acetyltransferase gene aac(6')-Im [corrected] associated with a sulI-type integron.

1997 ◽  
Vol 41 (2) ◽  
pp. 314-318 ◽  
Author(s):  
E Hannecart-Pokorni ◽  
F Depuydt ◽  
L de wit ◽  
E van Bossuyt ◽  
J Content ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Amino Acid ◽  
Resistance Gene ◽  
Citrobacter Freundii ◽  
Gram Negative ◽  
Gene Environment ◽  
Insert Region ◽  
Klebsiella Spp

The amikacin resistance gene aac(6')-Im [corrected] from Citrobacter freundii Cf155 encoding an aminoglycoside 6'-N-acetyltransferase was characterized. The gene was identified as a coding sequence of 521 bp located down-stream from the 5' conserved segment of an integron. The sequence of this aac(6')-Im [corrected] gene corresponded to a protein of 173 amino acids which possessed 64.2% identity in a 165-amino-acid overlap with the aac(6')-Ia gene product (F.C. Tenover, D. Filpula, K.L. Phillips, and J. J. Plorde, J. Bacteriol. 170:471-473, 1988). By using PCR, the aac(6')-Im [corrected] gene could be detected in 8 of 86 gram-negative clinical isolates from two Belgian hospitals, including isolates of Citrobacter, Klebsiella spp., and Escherichia coli. PCR mapping of the aac(6')-Im [corrected] gene environment in these isolates indicated that the gene was located within a sulI-type integron; the insert region is 1,700 bases long and includes two genes cassettes, the second being ant (3")-Ib.

scholarly journals The Antibacterial Activity of Human Neutrophils and Eosinophils Requires Proton Channels but Not BK Channels

2006 ◽  
Vol 127 (6) ◽  
pp. 659-672 ◽  
Author(s):  
Jon K. Femling ◽  
Vladimir V. Cherny ◽  
Deri Morgan ◽  
Balázs Rada ◽  
A. Paige Davis ◽  
...  
Keyword(s):  
Nadph Oxidase ◽  
Respiratory Burst ◽  
Essential Role ◽  
Outward Current ◽  
Bk Channels ◽  
Bk Channel ◽  
Human Neutrophils ◽  
H2o2 Production ◽  
Proton Channels ◽  
Voltage Gated

Electrophysiological events are of central importance during the phagocyte respiratory burst, because NADPH oxidase is electrogenic and voltage sensitive. We investigated the recent suggestion that large-conductance, calcium-activated K+ (BK) channels, rather than proton channels, play an essential role in innate immunity (Ahluwalia, J., A. Tinker, L.H. Clapp, M.R. Duchen, A.Y. Abramov, S. Page, M. Nobles, and A.W. Segal. 2004. Nature. 427:853–858). In PMA-stimulated human neutrophils or eosinophils, we did not detect BK currents, and neither of the BK channel inhibitors iberiotoxin or paxilline nor DPI inhibited any component of outward current. BK inhibitors did not inhibit the killing of bacteria, nor did they affect NADPH oxidase-dependent degradation of bacterial phospholipids by extracellular gIIA-PLA2 or the production of superoxide anion (\batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{O}_{2^{.}}^{{-}}\) \end{document}). Moreover, an antibody against the BK channel did not detect immunoreactive protein in human neutrophils. A required role for voltage-gated proton channels is demonstrated by Zn2+ inhibition of NADPH oxidase activity assessed by H2O2 production, thus validating previous studies showing that Zn2+ inhibited \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{O}_{2^{.}}^{{-}}\) \end{document} production when assessed by cytochrome c reduction. In conclusion, BK channels were not detected in human neutrophils or eosinophils, and BK inhibitors did not impair antimicrobial activity. In contrast, we present additional evidence that voltage-gated proton channels serve the essential role of charge compensation during the respiratory burst.

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