p40phox participates in the activation of NADPH oxidase by increasing the affinity of p47phox for flavocytochrome b558

2000 ◽  
Vol 349 (1) ◽  
pp. 113-117 ◽  
Author(s):  
Andrew R. CROSS
Keyword(s):  
Nadph Oxidase ◽  
Innate Immune System ◽  
Innate Immune ◽  
Its Sequence ◽  
Oxygen Species ◽  
Free System ◽  
Gtp Binding ◽  
Flavocytochrome B558 ◽  
Reported Data ◽  
Nadph Oxidase Activation

NADPH oxidase is one of the major components of the innate immune system and is used by phagocytes to generate microbicidal reactive oxygen species. Activation of the enzyme requires the participation of a minimum of five proteins, p22phox, gp91phox (together forming flavocytochrome b558), p47phox, p67phox and the GTP-binding protein, Rac2. A sixth protein, p40phox, has been implicated in the control of the activity of NADPH oxidase principally based on its sequence homology to, and physical association with, other phox components, and also the observation that it is phosphorylated during neutrophil activation. However, to date its role in regulating the activity of the enzyme has remained obscure, with evidence for both positive and negative influences on oxidase activity having being reported. Data are presented here using the cell-free system for NADPH oxidase activation that shows that p40phox can function to promote oxidase activation by increasing the affinity of p47phox for the enzyme approx. 3-fold.

scholarly journals Function of wild-type or mutant Rac2 and Rap1a GTPases in differentiated HL60 cell NADPH oxidase activation

Blood ◽  
1995 ◽  
Vol 85 (3) ◽  
pp. 804-811 ◽  
Author(s):  
TG Gabig ◽  
CD Crean ◽  
PL Mantel ◽  
R Rosli
Keyword(s):  
Plasma Membrane ◽  
Nadph Oxidase ◽  
Cell Line ◽  
Cell Lines ◽  
Wild Type ◽  
Free System ◽  
Hl60 Cells ◽  
Cell Free System ◽  
Nadph Oxidase Activation ◽  
O2 Production

Studies of neutrophil nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation in a cell-free system showed that the low molecular-weight guanosine triphosphatase (GTPase) Rac was required, and that Rap1a may participate in activation of the catalytic complex. Full-length posttranslationally modified Rac2 was active, whereas only the 1–166 truncated form of Rap1a was functional in the cell-free system, and thus, clarification of the function of Rap1a and Rac2 in intact human phagocytes is needed to provide further insight into their roles as signal transducers from plasma membrane receptors. In the present studies, oligonucleotide-directed mutagenesis was used to introduce a series of mutations into human rap1a or rac2 in the mammalian expression vector pSR alpha neo. HL60 cells transfected with wild-type or mutated rac2 or rap1a cDNA constructs and control HL60 cells transfected with the pSR alpha neo vector containing no inserted cDNA were selected in G418-containing media, then subclones were isolated. Compared with the parent HL60 cells, each of the stable transfected cell lines differentiated similarly into neutrophil-like cells and expressed comparable levels of NADPH oxidase components p47- phox, p67-phox and gp91-phox. The differentiated vector control cell line produced O2. in response to receptor stimulation at rates that were not significantly different from parent HL60 cells. O2-. production by differentiated cell lines expressing mutated N17 Rap1a or N17 Rac2 dominant-negative proteins was inhibited, whereas O2-. production by the subline overexpressing wild-type Rap1a was increased by fourfold. O2-. production by the differentiated cell line expressing GTPase-defective V12 Rap1a was also significantly inhibited, a finding that is consistent with a requirement for cycling between guanosine diphosphate- and GTP-bound forms of Rap1a for continuous NADPH oxidase activation in intact neutrophils. A model is proposed in which Rac2 mediates assembly of the p47 and p67 oxidase components on the cytosolic face of the plasma membrane via cytoskeletal reorganization, whereas Rap1a functions downstream as the final activation switch involving direct physical interaction with the transmembrane flavocytochrome component of the NADPH oxidase.

scholarly journals Hypertension and Erectile Dysfunction: Breaking Down the Challenges

2020 ◽  
Author(s):  
Amanda Almeida de Oliveira ◽  
Kenia Pedrosa Nunes
Keyword(s):  
Erectile Dysfunction ◽  
Innate Immune System ◽  
Innate Immune ◽  
Low Grade ◽  
Oxygen Species ◽  
Toll Like Receptor ◽  
Toll Like Receptor 4 ◽  
Corpora Cavernosa ◽  
Inflammatory State ◽  
Antioxidant Mechanisms

Abstract A diagnostic of hypertension increases the risk of erectile dysfunction (ED); likewise, ED can be an early sign of hypertension. In both cases, there is evidence that endothelial dysfunction is a common link between the 2 conditions. During hypertension, the sustained and widespread release of procontractile factors (e.g., angiotensin II, endothelin 1, and aldosterone) impairs the balance between vasoconstrictors and vasodilators and, in turn, detrimentally impacts vascular and erectile structures. This prohypertensive state associates with an enhancement in the generation of reactive oxygen species, which is not compensated by internal antioxidant mechanisms. Recently, the innate immune system, mainly via Toll-like receptor 4, has also been shown to actively contribute to the pathophysiology of hypertension and ED not only by inducing oxidative stress but also by sustaining a low-grade inflammatory state. Furthermore, some drugs used to treat hypertension can cause ED and, consequently, reduce compliance with the prescribed pharmacotherapy. To break down these challenges, in this review, we focus on discussing the well-established as well as the emerging mechanisms linking hypertension and ED with an emphasis on the signaling network of the vasculature and corpora cavernosa, the vascular-like structure of the penis.

scholarly journals Anaplasma phagocytophilum Utilizes Multiple Host Evasion Mechanisms To Thwart NADPH Oxidase-Mediated Killing during Neutrophil Infection

2004 ◽  
Vol 72 (8) ◽  
pp. 4772-4783 ◽  
Author(s):  
Jason A. Carlyon ◽  
Dalia Abdel Latif ◽  
Marc Pypaert ◽  
Paige Lacy ◽  
Erol Fikrig
Keyword(s):  
Nadph Oxidase ◽  
Anaplasma Phagocytophilum ◽  
Bacterial Pathogen ◽  
Etiologic Agent ◽  
Oxygen Species ◽  
Free System ◽  
Nadph Oxidase Complex ◽  
A Cell ◽  
Dose Dependent ◽  
Secondary Activation

ABSTRACT Anaplasma phagocytophilum, the etiologic agent of human anaplasmosis, is a bacterial pathogen that specifically colonizes neutrophils. Neutrophils utilize the NADPH oxidase complex to generate superoxide (O2 −) and initiate oxidative killing of microorganisms. A. phagocytophilum's unique tropism for neutrophils, however, indicates that it subverts and/or avoids oxidative killing. We therefore examined the effects of A. phagocytophilum infection on neutrophil NADPH oxidase assembly and reactive oxygen species (ROS) production. Following neutrophil binding, Anaplasma invasion requires at least 240 min. During its prolonged association with the neutrophil plasma membrane, A. phagocytophilum stimulates NADPH oxidase assembly, as indicated by increased cytochrome b 558 mobilization to the membrane, as well as colocalization of Rac and p22phox. This initial stimulation taxes the host neutrophil's finite oxidase reserves, as demonstrated by time- and bacterial-dose-dependent decreases in secondary activation by N-formyl-methionyl-leucyl-phenylalanine (FMLP) or phorbol myristate acetate (PMA). This stimulation is modest, however, and does not diminish oxidase stores to nearly the extent that Escherichia coli, serum-opsonized zymosan, FMLP, or PMA do. Despite the apparent activation of NADPH oxidase, no change in ROS-dependent chemiluminescence is observed upon the addition of A. phagocytophilum to neutrophils, indicating that the bacterium may scavenge exogenous O2 −. Indeed, A. phagocytophilum rapidly detoxifies O2 − in a cell-free system. Once internalized, the bacterium resides within a protective vacuole that excludes p22phox and gp91phox. Thus, A. phagocytophilum employs at least two strategies to protect itself from neutrophil NADPH oxidase-mediated killing.

scholarly journals Inflammatory Properties and Adjuvant Potential of Synthetic Glycolipids Homologous to Mycolate Esters of the Cell Wall of Mycobacterium tuberculosis

2016 ◽  
Vol 9 (2) ◽  
pp. 162-180 ◽  
Author(s):  
Hermann Giresse Tima ◽  
Juma''a Raheem Al Dulayymi ◽  
Olivier Denis ◽  
Pauline Lehebel ◽  
Klarah Sherzad Baols ◽  
...  
Keyword(s):  
Cell Wall ◽  
Innate Immune System ◽  
Complex Mixture ◽  
Innate Immune ◽  
Oxygen Species ◽  
Subunit Vaccines ◽  
Mycolic Acids ◽  
Trehalose Dimycolate ◽  
Tnf Α ◽  
Pro Inflammatory Cytokines

The cell wall of mycobacteria is characterised by glycolipids composed of different classes of mycolic acids (MAs; alpha-, keto-, and methoxy-) and sugars (trehalose, glucose, and arabinose). Studies using mutant Mtb strains have shown that the structure of MAs influences the inflammatory potential of these glycolipids. As mutant Mtb strains possess a complex mixture of glycolipids, we analysed the inflammatory potential of single classes of mycolate esters of the Mtb cell wall using 38 different synthetic analogues. Our results show that synthetic trehalose dimycolate (TDM) and trehalose, glucose, and arabinose monomycolates (TMM, GMM, and AraMM) activate bone marrow-derived dendritic cells in terms of the production of pro-inflammatory cytokines (IL-6 and TNF-α) and reactive oxygen species, upregulation of costimulatory molecules, and activation of NLRP3 inflammasome by a mechanism dependent on Mincle. These findings demonstrate that Mincle receptor can also recognise pentose esters and seem to contradict the hypothesis that production of GMM is an escape mechanism used by pathogenic mycobacteria to avoid recognition by the innate immune system. Finally, our experiments indicate that TMM and GMM, as well as TDM, can promote Th1 and Th17 responses in mice in an OVA immunisation model, and that further analysis of their potential as novel adjuvants for subunit vaccines is warranted.

scholarly journals Integration of TRPC6 and NADPH oxidase activation in lysophosphatidylcholine-induced TRPC5 externalization

2017 ◽  
Vol 313 (5) ◽  
pp. C541-C555 ◽  
Author(s):  
Pinaki Chaudhuri ◽  
Michael A. Rosenbaum ◽  
Lutz Birnbaumer ◽  
Linda M. Graham
Keyword(s):  
Reactive Oxygen Species ◽  
Nadph Oxidase ◽  
Transient Receptor Potential ◽  
Reactive Oxygen ◽  
Oxidation Products ◽  
Oxygen Species ◽  
Subsequent Increase ◽  
Erk Activation ◽  
Lipid Oxidation Products ◽  
Nadph Oxidase Activation

Lipid oxidation products, including lysophosphatidylcholine (lysoPC), activate canonical transient receptor potential 6 (TRPC6) channels, and the subsequent increase in intracellular Ca2+ leads to TRPC5 activation. The goal of this study is to elucidate the steps in the pathway between TRPC6 activation and TRPC5 externalization. Following TRPC6 activation by lysoPC, extracellular regulated kinase (ERK) is phosphorylated. This leads to phosphorylation of p47phox and subsequent NADPH oxidase activation with increased production of reactive oxygen species. ERK activation requires TRPC6 opening and influx of Ca2+ as evidenced by the failure of lysoPC to induce ERK phosphorylation in TRPC6−/− endothelial cells. ERK siRNA blocks the lysoPC-induced activation of NADPH oxidase, demonstrating that ERK activation is upstream of NADPH oxidase. The reactive oxygen species produced by NADPH oxidase promote myosin light chain kinase (MLCK) activation with phosphorylation of MLC and TRPC5 externalization. Downregulation of ERK, NADPH oxidase, or MLCK with the relevant siRNA prevents TRPC5 externalization. Blocking MLCK activation prevents the prolonged rise in intracellular calcium levels and preserves endothelial migration in the presence of lysoPC.

Sign in / Sign up

Export Citation Format

Share Document