scholarly journals A Functional NADPH Oxidase Prevents Caspase Involvement in the Clearance of Phagocytic Neutrophils

2007 ◽  
Vol 75 (7) ◽  
pp. 3256-3263 ◽  
Author(s):  
Rachel P. Wilkie ◽  
Margret C. M. Vissers ◽  
Mike Dragunow ◽  
Mark B. Hampton
Keyword(s):  
Nadph Oxidase ◽  
Caspase 3 ◽  
Caspase Activity ◽  
Wild Type ◽  
Caspase Activation ◽  
Effector Caspases ◽  
Nadph Oxidase Complex ◽  
Normal Human ◽  
Active Caspase

ABSTRACT Neutrophils play a prominent role in host defense. Phagocytosis of bacteria leads to the formation of an active NADPH oxidase complex that generates reactive oxygen species for bactericidal purposes. A critical step in the resolution of inflammation is the uptake of neutrophils by macrophages; however, there are conflicting reports on the mechanisms leading to the apoptosis of phagocytic neutrophils. The aim of this study was to clarify the role of effector caspases in these processes. Caspase activity was measured by DEVDase activity assays or immunofluorescence detection of active caspase-3. With normal human and wild-type murine neutrophils there was no caspase activation following phagocytosis of Staphylococcus aureus. However, caspase activity was observed in phagocytic neutrophils with a defective NADPH oxidase, including neutrophils isolated from X-linked gp91phox knockout chronic granulomatous disease mice. These results indicate that a functional NADPH oxidase and the generation of oxidants in the neutrophil phagosome prevent the activation of the cytoplasmic caspase cascade.

scholarly journals Activation of Membrane-associated Procaspase-3 Is Regulated by Bcl-2

1999 ◽  
Vol 144 (5) ◽  
pp. 915-926 ◽  
Author(s):  
Joseph F. Krebs ◽  
Robert C. Armstrong ◽  
Anu Srinivasan ◽  
Teresa Aja ◽  
Angela M. Wong ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Caspase 3 ◽  
Caspase Activity ◽  
Intracellular Membrane ◽  
Caspase Activation ◽  
Intracellular Membranes ◽  
Membrane Bound ◽  
Spontaneous Activation ◽  
Active Caspase

The mechanism by which membrane-bound Bcl-2 inhibits the activation of cytoplasmic procaspases is unknown. Here we characterize an intracellular, membrane-associated form of procaspase-3 whose activation is controlled by Bcl-2. Heavy membranes isolated from control cells contained a spontaneously activatable caspase-3 zymogen. In contrast, in Bcl-2 overexpressing cells, although the caspase-3 zymogen was still associated with heavy membranes, its spontaneous activation was blocked. However, Bcl-2 expression had little effect on the levels of cytoplasmic caspase activity in unstimulated cells. Furthermore, the membrane-associated caspase-3 differed from cytosolic caspase-3 in its responsiveness to activation by exogenous cytochrome c. Our results demonstrate that intracellular membranes can generate active caspase-3 by a Bcl-2–inhibitable mechanism, and that control of caspase activation in membranes is distinct from that observed in the cytoplasm. These data suggest that Bcl-2 may control cytoplasmic events in part by blocking the activation of membrane-associated procaspases.

Potential role of the NADPH oxidase NOX1 in the pathogenesis of 5-fluorouracil-induced intestinal mucositis in mice

2012 ◽  
Vol 302 (10) ◽  
pp. G1133-G1142 ◽  
Author(s):  
Masashi Yasuda ◽  
Shinichi Kato ◽  
Naoki Yamanaka ◽  
Maho Iimori ◽  
Daichi Utsumi ◽  
...  
Keyword(s):  
Nadph Oxidase ◽  
Caspase 3 ◽  
Potential Role ◽  
Chemotherapeutic Agent ◽  
Wild Type ◽  
Villus Height ◽  
Tnf Α ◽  
Nadph Oxidase 1 ◽  
Intestinal Mucositis

Although NADPH oxidase 1 (NOX1) has been shown to be highly expressed in the gastrointestinal tract, the physiological and pathophysiological roles of this enzyme are not yet fully understood. In the present study, we investigated the role of NOX1 in the pathogenesis of intestinal mucositis induced by the cancer chemotherapeutic agent 5-fluorouracil (5-FU) in mice. Intestinal mucositis was induced in Nox1 knockout (Nox1KO) and littermate wild-type (WT) mice via single, daily administration of 5-FU for 5 days. In WT mice, 5-FU caused severe intestinal mucositis characterized by a shortening of villus height, a disruption of crypts, a loss of body weight, and diarrhea. In Nox1KO mice, however, the severity of mucositis was significantly reduced, particularly with respect to crypt disruption. The numbers of apoptotic caspase-3- and caspase-8-activated cells in the intestinal crypt increased 24 h after the first 5-FU administration but were overall significantly lower in Nox1KO than in WT mice. Furthermore, the 5-FU-mediated upregulation of TNF-α, IL-1β, and NOX1 and the production of reactive oxygen species were significantly attenuated in Nox1KO mice compared with that in WT mice. These findings suggest that NOX1 plays an important role in the pathogenesis of 5-FU-induced intestinal mucositis. NOX1-derived ROS production following administration of 5-FU may promote the apoptotic response through upregulation of inflammatory cytokines.

scholarly journals Impaired Akt Activity Down-Modulation, Caspase-3 Activation, and Apoptosis in Cells Expressing a Caspase-resistant Mutant of RasGAP at Position 157

2005 ◽  
Vol 16 (8) ◽  
pp. 3511-3520 ◽  
Author(s):  
Jiang-Yan Yang ◽  
Joël Walicki ◽  
David Michod ◽  
Gilles Dubuis ◽  
Christian Widmann
Keyword(s):  
Marked Reduction ◽  
Caspase 3 ◽  
Resistant Mutant ◽  
Akt Pathway ◽  
Caspase Activity ◽  
Cleavage Sites ◽  
Wild Type ◽  
Efficient Processing ◽  
In Cells

RasGAP bears two caspase-3 cleavage sites that are used sequentially as caspase activity increases in cells. When caspase-3 is mildly activated, RasGAP is first cleaved at position 455. This leads to the production of an N-terminal fragment, called fragment N, that activates the Ras-PI3K-Akt pathway and that promotes cell survival. At higher caspase activity, RasGAP is further cleaved at position 157 generating two small N-terminal fragments named N1 and N2. We have now determined the contribution of this second cleavage event in the regulation of apoptosis using cells in which the wild-type RasGAP gene has been replaced by a cDNA encoding a RasGAP mutant that cannot be cleaved at position 157. Our results show that cleavage of fragment N at position 157 leads to a marked reduction in Akt activity. This is accompanied by efficient processing of caspase-3 that favors cell death in response to various apoptotic stimuli. In nontumorigenic cells, fragments N1 and N2 do not modulate apoptosis. Therefore, the role of the second caspase-mediated cleavage of RasGAP is to allow the inactivation of the antiapoptotic function of fragment N so that caspases are no longer hampered in their ability to kill cells.

scholarly journals Role of l-amino acid oxidase isolated from Calloselasma rhodostoma venom on neutrophil NADPH oxidase complex activation

Toxicon ◽  
2018 ◽  
Vol 145 ◽  
pp. 48-55 ◽  
Author(s):  
Mauro Valentino Paloschi ◽  
Charles Nunes Boeno ◽  
Jéssica Amaral Lopes ◽  
André Eduardo dos Santos da Rosa ◽  
Weverson Luciano Pires ◽  
...  
Keyword(s):  
Amino Acid ◽  
Nadph Oxidase ◽  
Acid Oxidase ◽  
Amino Acid Oxidase ◽  
Nadph Oxidase Complex ◽  
Calloselasma Rhodostoma

scholarly journals Thimerosal-Derived Ethylmercury Is a Mitochondrial Toxin in Human Astrocytes: Possible Role of Fenton Chemistry in the Oxidation and Breakage of mtDNA

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Martyn A. Sharpe ◽  
Andrew D. Livingston ◽  
David S. Baskin
Keyword(s):  
Hydrogen Peroxide ◽  
Caspase 3 ◽  
Permeability Transition ◽  
Fold Increase ◽  
Hydrogen Peroxide Production ◽  
Fenton Chemistry ◽  
Human Astrocytes ◽  
Mitochondrial Toxin ◽  
Normal Human

Thimerosal generates ethylmercury in aqueous solution and is widely used as preservative. We have investigated the toxicology of Thimerosal in normal human astrocytes, paying particular attention to mitochondrial function and the generation of specific oxidants. We find that ethylmercury not only inhibits mitochondrial respiration leading to a drop in the steady state membrane potential, but also concurrent with these phenomena increases the formation of superoxide, hydrogen peroxide, and Fenton/Haber-Weiss generated hydroxyl radical. These oxidants increase the levels of cellular aldehyde/ketones. Additionally, we find a five-fold increase in the levels of oxidant damaged mitochondrial DNA bases and increases in the levels of mtDNA nicks and blunt-ended breaks. Highly damaged mitochondria are characterized by having very low membrane potentials, increased superoxide/hydrogen peroxide production, and extensively damaged mtDNA and proteins. These mitochondria appear to have undergone a permeability transition, an observation supported by the five-fold increase in Caspase-3 activity observed after Thimerosal treatment.

scholarly journals Impaired Pulmonary NF-κB Activation in Response to Lipopolysaccharide in NADPH Oxidase-Deficient Mice

2001 ◽  
Vol 69 (10) ◽  
pp. 5991-5996 ◽  
Author(s):  
M. Audrey Koay ◽  
John W. Christman ◽  
Brahm H. Segal ◽  
Annapurna Venkatakrishnan ◽  
Thomas R. Blackwell ◽  
...  
Keyword(s):  
Nadph Oxidase ◽  
Intracellular Signaling ◽  
Lung Inflammation ◽  
Nuclear Translocation ◽  
Binding Activity ◽  
Wild Type ◽  
Inflammatory Protein ◽  
Macrophage Inflammatory Protein ◽  
Deficient Mice

ABSTRACT Reactive oxygen species (ROS) are thought to be involved in intracellular signaling, including activation of the transcription factor NF-κB. We investigated the role of NADPH oxidase in the NF-κB activation pathway by utilizing knockout mice (p47phox−/−) lacking the p47phox component of NADPH oxidase. Wild-type (WT) controls and p47phox−/−mice were treated with intraperitoneal (i.p.) Escherichia coli lipopolysaccharide (LPS) (5 or 20 μg/g of body weight). LPS-induced NF-κB binding activity and accumulation of RelA in nuclear protein extracts of lung tissue were markedly increased in WT compared to p47phox−/− mice 90 min after treatment with 20 but not 5 μg of i.p. LPS per g. In another model of lung inflammation, RelA nuclear translocation was reduced in p47phox−/− mice compared to WT mice following treatment with aerosolized LPS. In contrast to NF-κB activation in p47phox−/− mice, LPS-induced production of macrophage inflammatory protein 2 in the lungs and neutrophilic lung inflammation were not diminished in these mice compared to WT mice. We conclude that LPS-induced NF-κB activation is deficient in the lungs of p47phox−/− mice compared to WT mice, but this abnormality does not result in overt alteration in the acute inflammatory response.

Role of gp91phox-containing NADPH oxidase in left ventricular remodeling induced by intermittent hypoxic stress

2008 ◽  
Vol 294 (5) ◽  
pp. H2197-H2203 ◽  
Author(s):  
Tetsuya Hayashi ◽  
Chika Yamashita ◽  
Chika Matsumoto ◽  
Chol-Jun Kwak ◽  
Kiwako Fujii ◽  
...  
Keyword(s):  
Cardiovascular Diseases ◽  
Nadph Oxidase ◽  
Intermittent Hypoxia ◽  
Sleep Apnea Syndrome ◽  
Systolic Pressure ◽  
Left Ventricular ◽  
Hypoxic Stress ◽  
Wild Type ◽  
Lv Remodeling

Intermittent hypoxia due to sleep apnea syndrome is associated with cardiovascular diseases. However, the precise mechanisms by which intermittent hypoxic stress accelerates cardiovascular diseases are largely unclear. The aim of this study was to investigate the role of gp91 phox-containing NADPH oxidase in the development of left ventricular (LV) remodeling induced by intermittent hypoxic stress in mice. Male gp91 phox-deficient (gp91−/−) mice ( n = 26) and wild-type ( n = 39) mice at 7–12 wk of age were exposed to intermittent hypoxia (30 s of 4.5–5.5% O2 followed by 30 s of 21% O2 for 8 h/day during daytime) or normoxia for 10 days. Mean blood pressure and LV systolic and diastolic function were not changed by intermittent hypoxia in wild-type or gp91−/− mice, although right ventricular systolic pressure tended to be increased. In wild-type mice, intermittent hypoxic stress significantly increased the diameter of cardiomyocytes and interstitial fibrosis in LV myocardium. Furthermore, intermittent hypoxic stress increased superoxide production, 4-hydroxy-2-nonenal protein, TNF-α and transforming growth factor-β mRNA, and NF-κB binding activity in wild-type, but not gp91−/−, mice. These results suggest that gp91 phox-containing NADPH oxidase plays a crucial role in the pathophysiology of intermittent hypoxia-induced LV remodeling through an increase of oxidative stress.

The role of PI3Ks in the regulation of the neutrophil NADPH oxidase

2007 ◽  
Vol 74 ◽  
pp. 59-67 ◽  
Author(s):  
Phillip T. Hawkins ◽  
Keith Davidson ◽  
Len R. Stephens
Keyword(s):  
Nadph Oxidase ◽  
Microbial Pathogens ◽  
Nucleotide Exchange ◽  
Tight Control ◽  
Surface Receptors ◽  
Guanine Nucleotide Exchange ◽  
Nadph Oxidase Complex ◽  
Phosphoinositide 3 Kinase ◽  
Phox Homology

The NADPH oxidase complex of neutrophils and macrophages is an important weapon used by these cells to kill microbial pathogens. The regulation of this enzyme complex is necessarily complicated by the diverse receptor types that are needed to trigger its activation and also the tight control that is required to deliver this activation at the appropriate time and place. As such, several signalling pathways have been established to regulate the NADPH oxidase downstream of cell surface receptors. Central amongst these are PI3K- (phosphoinositide 3-kinase)-dependent pathways, blockade of which severely limits activation of the oxidase to several soluble and particulate stimuli. The precise roles of the phosphoinositide products of PI3K activity in regulating NADPH oxidase assembly and activation are still unclear, but there is emerging evidence that they play a key role via regulation of guanine nucleotide exchange on Rac, a key component in the oxidase complex. There is also very strong evidence that the PI3K products PtdIns(3,4)P2 and PtdIns3P can bind directly to the PX (Phox homology) domains of the core oxidase components p47phox and p40phox respectively. However, the significance of these interactions in terms of membrane localization or allosteric consequences for the oxidase complex remains to be established.

scholarly journals Caspase activation contributes to endotoxin-induced diaphragm weakness

2006 ◽  
Vol 100 (6) ◽  
pp. 1770-1777 ◽  
Author(s):  
Gerald S. Supinski ◽  
Leigh A. Callahan
Keyword(s):  
Caspase 3 ◽  
Muscle Force ◽  
Caspase Activation ◽  
Fluorogenic Substrate ◽  
Respiratory Muscle Weakness ◽  
Protein Levels ◽  
Diaphragmatic Weakness ◽  
Caspase Protein ◽  
Diaphragm Weakness ◽  
Active Caspase

Infections produce significant respiratory muscle weakness, but the mechanisms by which inflammation reduces muscle force remain incompletely understood. Recent work suggests that caspase 3 releases actin and myosin from the contractile protein lattice, so we postulated that infections may reduce skeletal muscle force by activating caspase 3. The present experiments were designed to test this hypothesis by determining 1) diaphragm caspase 3 activation in the diaphragm after endotoxin and 2) the effect of a broad-spectrum caspase inhibitor, Z-Val-Ala-Asp(OCH3)-fluoromethylketone (zVAD-fmk), and a selective caspase 3 inhibitor, N-acetyl-Asp-Glu-Val-Asp-al (DEVD-CHO), on endotoxin-induced diaphragm weakness. Caspase 3 activation was assessed by measuring caspase protein levels and by measuring cleavage of a fluorogenic substrate. Diaphragm force was measured in response to electrical stimulation (1–150 Hz). Caspase-mediated spectrin degradation was assessed by Western blotting. Parameters were compared in mice given saline, endotoxin (12 mg/kg ip), endotoxin plus zVAD-fmk (3 mg/kg iv), zVAD-fmk alone, or endotoxin plus DEVD-CHO (3 mg/kg iv). Endotoxin increased diaphragm active caspase 3 protein ( P < 0.003), increased caspase 3 activity ( P < 0.002), increased diaphragm spectrin degradation ( P < 0.001), and reduced diaphragm force ( P < 0.001). Administration of zVAD-fmk or DEVD-CHO prevented endotoxin-induced weakness (e.g., force in response to 150-Hz stimulation was 23.8 ± 1.4, 12.1 ± 1.3, 23.5 ± 0.8, 22.7 ± 1.3, and 24.4 ± 0.8 N/cm2, respectively, for control, endotoxin, endotoxin plus zVAD-fmk, endotoxin plus DEVD-CHO, and zVAD-fmk alone treated groups, P < 0.001). Caspase inhibitors also prevented spectrin degradation. In conclusion, endotoxin administration elicits significant diaphragm caspase 3 activation and caspase-mediated diaphragmatic weakness.

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