scholarly journals Regulation of 5-hydroxyeicosanoid dehydrogenase activity in monocytic cells

2007 ◽  
Vol 403 (1) ◽  
pp. 157-165 ◽  
Author(s):  
Karl-Rudolf Erlemann ◽  
Chantal Cossette ◽  
Gail E. Grant ◽  
Gue-Jae Lee ◽  
Pranav Patel ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Reverse Reaction ◽  
Eicosatetraenoic Acid ◽  
Resting Cells ◽  
U937 Cells ◽  
Forward Reaction ◽  
Monocytic Cells ◽  
Low Concentrations ◽  
Ping Pong ◽  
1,25 Dihydroxy Vitamin D3

The 5-lipoxygenase product 5-oxo-ETE (5-oxo-eicosatetraenoic acid) is a highly potent granulocyte chemoattractant that is synthesized from 5-HETE (5-hydroxyeicosatetraenoic acid) by 5-HEDH (5-hydroxyeicosanoid dehydrogenase). In the present study, we found that 5-HEDH activity is induced in U937 monocytic cells by differentiation towards macrophages with PMA and in HL-60 myeloblastic cells by 1,25-dihydroxy-vitamin D3. We used PMA-differentiated U937 cells to investigate further the regulation of 5-HEDH. This enzyme exhibits approx. 10000-fold selectivity for NADP+ over NAD+ as a cofactor for the oxidation of 5-HETE, which is maximal at pH 10.2. In contrast, the reverse reaction (5-oxo-ETE→5-HETE) is NADPH-dependent and is maximal at pH 6. Although the Km for the forward reaction (670 nM) is about twice that for the reverse reaction at neutral pH, the Vmax is approx 8-fold higher. The oxidation of 5-HETE to 5-oxo-ETE is supported by very low concentrations of NADP+ (Km 139 nM), inhibited by NADPH (Ki 224 nM) and is consistent with a ping-pong mechanism. The amount of 5-oxo-ETE synthesized by 5-HEDH depends on the ratio of NADP+ to NADPH. Exposure of U937 cells to oxidative stress (t-butyl hydroperoxide) increased the ratio of NADP+ to NADPH from approx. 0.08 in resting cells to approx. 3, and this was accompanied by a dramatic increase in 5-HETE oxidation to 5-oxo-ETE. We conclude that differentiation of monocytic cells towards macrophages results in enhanced 5-oxo-ETE synthesis and that the ability of cells to synthesize 5-oxo-ETE is tightly regulated by the ratio of intracellular NADP+ to NADPH.

scholarly journals NADPH-dependent reduction of 2,6-dichlorophenol-indophenol by the phagocytic vesicles of pig polymorphonuclear leucocytes

1983 ◽  
Vol 210 (2) ◽  
pp. 577-581 ◽  
Author(s):  
H Wakeyama ◽  
K Takeshige ◽  
S Minakami
Keyword(s):  
Oxidation Rate ◽  
Cetyltrimethylammonium Bromide ◽  
Reductase Activity ◽  
Tween 20 ◽  
Polymorphonuclear Leucocytes ◽  
Resting Cells ◽  
Low Concentrations ◽  
Km Value ◽  
Nadph Oxidation

NADPH-dependent 2,6-dichlorophenol-indophenol (DCIP) reductase activity in the homogenate of phagocytosing pig polymorphonuclear leucocytes was twice that of the resting cells and the activity in the phagocytic vesicles corresponded to the activity increment due to phagocytosis. The apparent Km value of the reductase activity in the vesicles for NADPH was 30 microM, which is similar to that of the NADPH-dependent superoxide (O2-) formation. Increasing the DCIP reductase activity by increasing the DCIP concentration caused a decrease in the O2- –forming activity, the NADPH oxidation rate being constant and independent of the dye concentration. p-Chloromercuribenzoate and cetyltrimethylammonium bromide at low concentrations inhibited the O2- –forming activity of the vesicles without inhibiting the DCIP reductase. Quinacrine inhibited both O2- formation and DCIP reduction. The DCIP reductase activity could be extracted with a mixture of deoxycholate and Tween-20, which extracts the O2- –forming activity. The reductase activity in the extract was enhanced 2-fold by the addition of FAD, and its apparent Km was 0.085 microM. These results indicate that the NADPH-dependent DCIP reductase activity of the phagocytic vesicles is catalysed by a flavin-containing component of the O2- –forming system.

scholarly journals Chemokines (CCL3, CCL4, and CCL5) Inhibit ATP-Induced Release of IL-1β by Monocytic Cells

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Anca-Laura Amati ◽  
Anna Zakrzewicz ◽  
Robin Siebers ◽  
Sigrid Wilker ◽  
Sarah Heldmann ◽  
...  
Keyword(s):  
Nicotinic Acetylcholine Receptors ◽  
Acetylcholine Receptors ◽  
Mononuclear Leukocytes ◽  
Main Function ◽  
U937 Cells ◽  
Monocytic Cells ◽  
Nicotinic Acetylcholine ◽  
Leukocyte Mobilization ◽  
Life Threatening ◽  
Calcium Independent Phospholipase A2

Chemokines and ATP are among the mediators of inflammatory sites that can enter the circulation via damaged blood vessels. The main function of chemokines is leukocyte mobilization, and ATP typically triggers inflammasome assembly. IL-1β, a potent inflammasome-dependent cytokine of innate immunity, is essential for pathogen defense. However, excessive IL-1β may cause life-threatening systemic inflammation. Here, we hypothesize that chemokines control ATP-dependent secretion of monocytic IL-1β. Lipopolysaccharide-primed human monocytic U937 cells were stimulated with the P2X7 agonist BzATP for 30 min to induce IL-1β release. CCL3, CCL4, and CCL5 dose dependently inhibited BzATP-stimulated release of IL-1β, whereas CXCL16 was ineffective. The effect of CCL3 was confirmed for primary mononuclear leukocytes. It was blunted after silencing CCR1 or calcium-independent phospholipase A2 (iPLA2) by siRNA and was sensitive to antagonists of nicotinic acetylcholine receptors containing subunits α7 and α9. U937 cells secreted small factors in response to CCL3 that mediated the inhibition of IL-1β release. We suggest that CCL chemokines inhibit ATP-induced release of IL-1β from U937 cells by a triple-membrane-passing mechanism involving CCR, iPLA2, release of small mediators, and nicotinic acetylcholine receptor subunits α7 and α9. We speculate that whenever chemokines and ATP enter the circulation concomitantly, systemic release of IL-1β is minimized.

Acrylamide-induced oxidative stress in human erythrocytes

2009 ◽  
Vol 28 (10) ◽  
pp. 611-617 ◽  
Author(s):  
Betul Catalgol ◽  
Gül Özhan ◽  
Buket Alpertunga
Keyword(s):  
Oxidative Stress ◽  
Reduced Glutathione ◽  
Human Erythrocytes ◽  
Antioxidant Enzyme Activities ◽  
Total Glutathione ◽  
Sod Activity ◽  
Spectrophotometric Methods ◽  
Low Concentrations ◽  
Different Doses

Acrylamide (AA), a widely used industrial chemical, is shown to be neurotoxic, mutagenic and carcinogenic. This study was carried out to investigate the effects of different doses of AA on lipid peroxidation (LPO), haemolysis, methaemoglobin (MetHb) and antioxidant system in human erythrocytes in vitro. Erythrocyte solutions were incubated with 0.10, 0.25, 0.50 and 1.00 mM of AA at 37°C for 1 hour. At the end of the incubation, malondialdehyde (MDA), an end product of LPO, was determined by liquid chromatography (LC) while total glutathione, reduced glutathione (GSH) levels, activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) enzymes and the rates of haemolysis and MetHb were determined by spectrophotometric methods. All of the studied concentrations of AA increased MetHb formation and SOD activity, and induced MDA formation and haemolysis due to the destruction of erythrocyte cell membrane. AA caused a decrease in the activities of GSH-Px, CAT and GSH levels. However, these effects of AA were seen only at higher concentrations than AA intake estimated for populations in many countries. We suggest that LPO process may not be involved in the toxic effects of AA in low concentrations, although the present results showed that the studied concentrations of AA exert deteriorating effects on antioxidant enzyme activities, LPO process and haemolysis.

scholarly journals A Unique GTP-Dependent Sporulation Sensor Histidine Kinase in Bacillus anthracis

2008 ◽  
Vol 191 (3) ◽  
pp. 687-692 ◽  
Author(s):  
Francesca Scaramozzino ◽  
Andrea White ◽  
Marta Perego ◽  
James A. Hoch
Keyword(s):  
Bacillus Anthracis ◽  
Histidine Kinase ◽  
Catalytic Domain ◽  
Coiled Coil ◽  
Reverse Reaction ◽  
Forward Reaction ◽  
Critical Signal ◽  
Sensor Histidine Kinase ◽  
Virulence Plasmids ◽  
Kinase Catalytic Domain

ABSTRACT The Bacillus anthracis BA2291 gene codes for a sensor histidine kinase involved in the induction of sporulation. Genes for orthologs of the sensor domain of the BA2291 kinase exist in virulence plasmids in this organism, and these proteins, when expressed, inhibit sporulation by converting BA2291 to an apparent phosphatase of the sporulation phosphorelay. Evidence suggests that the sensor domains inhibit BA2291 by titrating its activating signal ligand. Studies with purified BA2291 revealed that this kinase is uniquely specific for GTP in the forward reaction and GDP in the reverse reaction. The G1 motif of BA2291 is highly modified from ATP-specific histidine kinases, and modeling this motif in the structure of the kinase catalytic domain suggested how guanine binds to the region. A mutation in the putative coiled-coil linker between the sensor domain and the catalytic domains was found to decrease the rate of the forward autophosphorylation reaction and not affect the reverse reaction from phosphorylated Spo0F. The results suggest that the activating ligand for BA2291 is a critical signal for sporulation and in a limited concentration in the cell. Decreasing the response to it either by slowing the forward reaction through mutation or by titration of the ligand by expressing the plasmid-encoded sensor domains switches BA2291 from an inducer to an inhibitor of the phosphorelay and sporulation.

scholarly journals Zinc Chloride Exposure Inhibits Brain Acetylcholine Levels, Produces Neurotoxic Signatures, and Diminishes Memory and Motor Activities in Adult Zebrafish

2018 ◽  
Vol 19 (10) ◽  
pp. 3195 ◽  
Author(s):  
Sreeja Sarasamma ◽  
Gilbert Audira ◽  
Stevhen Juniardi ◽  
Bonifasius Sampurna ◽  
Sung-Tzu Liang ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Zinc Chloride ◽  
Short Term Memory ◽  
Amyloid Β ◽  
Antioxidant Defense System ◽  
Significant Inhibition ◽  
Control Group ◽  
Adult Zebrafish ◽  
Zebrafish Model ◽  
Low Concentrations

In this study, we evaluated the acute (24, 48, 72, and 96 h) and chronic (21 days) adverse effects induced by low doses (0.1, 0.5, 1, and 1.5 mg/L) of zinc chloride (ZnCl2) exposure in adult zebrafish by using behavioral endpoints like three-dimensional (3D) locomotion, passive avoidance, aggression, circadian rhythm, and predator avoidance tests. Also, brain tissues were dissected and subjected to analysis of multiple parameters related to oxidative stress, antioxidant responses, superoxide dismutase (SOD), neurotoxicity, and neurotransmitters. The results showed that ZnCl2-exposed fishes displayed decreased locomotor behavior and impaired short-term memory, which caused an Alzheimer’s Disease (AD)-like syndrome. In addition, low concentrations of ZnCl2 induced amyloid beta (amyloid β) and phosphorylated Tau (p-Tau) protein levels in brains. In addition, significant induction in oxidative stress indices (reactive oxygen species (ROS) and malondialdehyde (MDA)), reduction in antioxidant defense system (glutathione (GSH), GSH peroxidase (GSH-Px) and SOD) and changes in neurotransmitters were observed at low concentrations of ZnCl2. Neurotoxic effects of ZnCl2 were observed with significant inhibition of acetylcholine (ACh) activity when the exposure dose was higher than 1 ppm. Furthermore, we found that zinc, metallothionein (MT), and cortisol levels in brain were elevated compared to the control group. A significantly negative correlation was observed between memory and acetylcholinesterase (AChE) activity. In summary, these findings revealed that exposure to ZnCl2 affected the behavior profile of zebrafish, and induced neurotoxicity which may be associated with damaged brain areas related to memory. Moreover, our ZnCl2-induced zebrafish model may have potential for AD-associated research in the future.

Human Monocytoid Leukemia Cells Are Highly Sensitive to Apoptosis Induced by 2′-Deoxycoformycin and 2′-Deoxyadenosine: Association With dATP-Dependent Activation of Caspase-3

Blood ◽  
1998 ◽  
Vol 92 (9) ◽  
pp. 3368-3375 ◽  
Author(s):  
Nozomi Niitsu ◽  
Yuri Yamaguchi ◽  
Masanori Umeda ◽  
Yoshio Honma
Keyword(s):  
Cell Lines ◽  
Caspase 3 ◽  
Lymphoma Cell ◽  
Leukemia Cells ◽  
Acute Monocytic Leukemia ◽  
U937 Cells ◽  
Monocytic Leukemia ◽  
Low Concentrations ◽  
American Society ◽  
Induced Apoptosis

Abstract The adenosine deaminase (ADA) inhibitor 2′-deoxycoformycin (dCF) significantly inhibits the proliferation of leukemia and lymphoma cell lines. When cells were incubated in the presence of both dCF and 2′-deoxyadenosine (dAd), the concentration of dCF required to induce apoptosis of monocytoid leukemia cells was much lower than that required for myeloid, erythroid, or lymphoma cell lines. Among the cell lines tested, U937 cells were the most sensitive to this treatment. The concentration of dCF that effectively inhibited the proliferation of U937 cells was 1/1,000 of that required for lymphoma cell lines, on a molar basis. However, the uptake of dCF or dAd in U937 cells was comparable with that in other leukemia and lymphoma cell lines. The intracellular accumulation of dATP in U937 cells was only slightly higher than that in other leukemia cells in dCF-treated culture. Treatment with dCF plus dAd induced apoptosis in U937 cells at low concentrations, and this apoptosis was reduced by treatment with caspase inhibitors. Induction of caspase-3 (CPP32) activity accompanied the apoptosis induced by dCF plus dAd. No activation of CPP32 was observed in cytosol prepared from exponentially growing leukemia and lymphoma cells. However, dATP effectively induced CPP32 activation in cytosol from monocytoid cells, but not in that from nonmonocytoid cells, suggesting that dATP-dependent CPP32 activation is at least partly involved in the preferential induction of apoptosis in monocytoid leukemia cells. The combination of dCF and dAd may be useful for the clinical treatment of acute monocytic leukemia. © 1998 by The American Society of Hematology.

scholarly journals NF-κB-Dependent Production of ROS and Restriction of HSV-1 Infection in U937 Monocytic Cells

Viruses ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 428 ◽  
Author(s):  
Francesca Marino-Merlo ◽  
Emanuela Papaianni ◽  
Caterina Frezza ◽  
Silvana Pedatella ◽  
Mauro De Nisco ◽  
...  
Keyword(s):  
Cell Types ◽  
Dominant Negative ◽  
Ros Generation ◽  
Neural Cells ◽  
Ros Production ◽  
U937 Cells ◽  
Herpes Simplex Virus 1 ◽  
Monocytic Cells ◽  
Wide Range ◽  
Hsv 1

Herpes simplex virus 1 (HSV-1) can infect a wide range of cell types, including cells of the adaptive and innate immunity but, normally, it completes a fully-permissive replication cycle only in epithelial or neural cells. Complex mechanisms controlling this delicate balance in immune cells and consequent restriction of HSV-1 infection in these cells have not been completely elucidated. We have recently demonstrated that the transcription factor nuclear factor kappa B (NF-κB) can act as a main permissiveness regulator of HSV-1 infection in monocytic cells, however, mediators involved in this regulation have not been identified. To better define mechanisms involved in this phenomenon and, particularly, the possible involvement of ROS, wild type U937 cells or U937 cells stably transfected with a dominant-negative (DN) IκB-mutant and selenium-containing compounds, as anti-oxidants, were utilized. The main results can be summarized as follows. HSV-1 infection induces an immediate ROS production in U937 monocytic cells that can efficiently activate NF-κB but not in DN-IκB-mutant cells. Treatment with selenium-containing antioxidants efficiently inhibited HSV-1-induced ROS generation while producing increased levels of HSV-1 replication and a reduction of HSV-1-induced NF-κB activation in U937 monocytic cells. Our results suggest a scenario in which an efficient NF-κB-dependent ROS production in response to infection could contribute in limiting HSV-1 replication in monocytes/macrophages, thus avoiding possible irreparable damage to the innate immune system of the host during HSV-1 infection.

scholarly journals Cardiovascular Effects of PCB 126 (3,3’,4,4’,5-Pentachlorobiphenyl) in Zebrafish Embryos and Impact of Co-Exposure to Redox Modulating Chemicals

2019 ◽  
Vol 20 (5) ◽  
pp. 1065 ◽  
Author(s):  
Elisabet Teixidó ◽  
Marta Barenys ◽  
Ester Piqué ◽  
Joan Llobet ◽  
Jesús Gómez-Catalán
Keyword(s):  
Oxidative Stress ◽  
Developmental Toxicity ◽  
Environmental Pollutants ◽  
Cardiovascular Effects ◽  
Zebrafish Embryos ◽  
Oxidative Potential ◽  
Antioxidant Genes ◽  
Aryl Hydrocarbon ◽  
Low Concentrations ◽  
Pericardial Edema

The developing cardiovascular system of zebrafish is a sensitive target for many environmental pollutants, including dioxin-like compounds and pesticides. Some polychlorinated biphenyls (PCBs) can compromise the cardiovascular endothelial function by activating oxidative stress-sensitive signaling pathways. Therefore, we exposed zebrafish embryos to PCB126 or to several redox-modulating chemicals to study their ability to modulate the dysmorphogenesis produced by PCB126. PCB126 produced a concentration-dependent induction of pericardial edema and circulatory failure, and a concentration-dependent reduction of cardiac output and body length at 80 hours post fertilization (hpf). Among several modulators tested, the effects of PCB126 could be both positively and negatively modulated by different compounds; co-treatment with α-tocopherol (vitamin E liposoluble) prevented the adverse effects of PCB126 in pericardial edema, whereas co-treatment with sodium nitroprusside (a vasodilator compound) significantly worsened PCB126 effects. Gene expression analysis showed an up-regulation of cyp1a, hsp70, and gstp1, indicative of PCB126 interaction with the aryl hydrocarbon receptor (AhR), while the transcription of antioxidant genes (sod1, sod2; cat and gpx1a) was not affected. Further studies are necessary to understand the role of oxidative stress in the developmental toxicity of low concentrations of PCB126 (25 nM). Our results give insights into the use of zebrafish embryos for exploring mechanisms underlying the oxidative potential of environmental pollutants.

Kinetic Characteristics, Substrate Specificity and Catalytic Properties of Phosphoserine Aminotransferase from the Green Alga Scenedesmus obliquus, Mutant C-2A

1995 ◽  
Vol 50 (9-10) ◽  
pp. 630-637 ◽  
Author(s):  
M. Stolz ◽  
D. Dörnemann
Keyword(s):  
Catalytic Properties ◽  
Scenedesmus Obliquus ◽  
Initial Reaction ◽  
Kinetic Characteristics ◽  
Forward Reaction ◽  
Phosphoserine Aminotransferase ◽  
Substrate Analogues ◽  
Ping Pong ◽  
The One ◽  
Competitive Substrate

Abstract Phosphoserine am inotransferase (EC 2.6.1.52) has been purified from Scenedesmus obliquus. mutant C -2A′, as reported previously (Stolz and Dörnemann, 1994). The current studies on its catalytic properties, involving initial reaction velocities as a function of the phosphoserine concentration at various fixed concentrations of 2-oxoglutarate as aminoacceptor, indicate a bi-bi ping pong mechanism . The application of a variety of substrate analogues of phosphoserine revealed no significant metabolisation of these com pounds and thus a considerable specificity of the enzyme. 4,5-dioxovalerate with glutamate as am inodonor is effective as competitive substrate to phosphohydroxypyruvate in the forward reaction and yields 5-am inolevulinate. 4.5-Dioxovalerate and glutam ate-1-semialdehyde can both serve as competitive aminoacceptor in the reverse reaction with phosphoserine and as substrate with 2-oxoglutarate as am inoacceptor. Comparison of the phosphoserine transamination with the transamination of 4,5-dioxovalerate revealed for both reactions a pH -optim um of 6 .8 -7 .0 in Mes/Bis-Trisbuffer. How ever, the Km-values and the Vmax for phosphoserine and 2-oxoglutarate on the one side, and 4,5-dioxovalerate and glutamate on the other were found to differ by orders of magnitude

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