101
|
Ueyama T, Kusakabe T, Karasawa S, Kawasaki T, Shimizu A, Son J, Leto TL, Miyawaki A, Saito N. Sequential binding of cytosolic Phox complex to phagosomes through regulated adaptor proteins: evaluation using the novel monomeric Kusabira-Green System and live imaging of phagocytosis. THE JOURNAL OF IMMUNOLOGY 2008; 181:629-40. [PMID: 18566430 DOI: 10.4049/jimmunol.181.1.629] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We engineered a method for detecting intramolecular and intermolecular phox protein interactions in cells by fluorescence microscopy using fusion proteins of complementary fragments of a coral fluorescent reporter protein (monomeric Kusabira-Green). We confirmed the efficacy of the monomeric Kusabira-Green system by showing that the PX and PB1 domains of p40phox interact in intact cells, which we suggested maintains this protein in an inactive closed conformation. Using this system, we also explored intramolecular interactions within p47phox and showed that the PX domain interacts with the autoinhibited tandem Src homology 3 domains maintained in contact with the autoinhibitory region, along with residues 341-360. Furthermore, we demonstrated sequential interactions of p67phox with phagosomes involving adaptor proteins, p47phox and p40phox, during FcgammaR-mediated phagocytosis. Although p67phox is not targeted to phagosomes by itself, p47phox functions as an adaptor for the ternary complex (p47phox-p67phox-p40phox) in early stages of phagocytosis before phagosome closure, while p40phox functions in later stages after phagosomal closure. Interestingly, a mutated "open" form of p40phox linked p47phox to closed phagosomes and prolonged p47phox and p67phox retention on phagosomes. These results indicate that binding of the ternary complex to phagosomes can be temporally regulated by switching between adaptor proteins that have PX domains with distinct lipid-binding specificities.
Collapse
Affiliation(s)
- Takehiko Ueyama
- Laboratory of Molecular Pharmacology, Biosignal Research Center, Kobe University, Kobe, Japan
| | | | | | | | | | | | | | | | | |
Collapse
|
102
|
Abstract
Phagocytic leukocytes consume oxygen and generate reactive oxygen species in response to appropriate stimuli. The phagocyte NADPH oxidase, a multiprotein complex, existing in the dissociated state in resting cells becomes assembled into the functional oxidase complex upon stimulation and then generates superoxide anions. Biochemical aspects of the NADPH oxidase are briefly discussed in this review; however, the major focus relates to the contributions of various modes of microscopy to our understanding of the NADPH oxidase and the cell biology of phagocytic leukocytes.
Collapse
|
103
|
Bréchard S, Tschirhart EJ. Regulation of superoxide production in neutrophils: role of calcium influx. J Leukoc Biol 2008; 84:1223-37. [PMID: 18519744 PMCID: PMC2567897 DOI: 10.1189/jlb.0807553] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Upon stimulation, activation of NADPH oxidase complexes in neutrophils produces a burst of superoxide anions contributing to oxidative stress and the development of inflammatory process. Store-operated calcium entry (SOCE), whereby the depletion of intracellular stores induces extracellular calcium influx, is known to be a crucial element of NADPH oxidase regulation. However, the mechanistic basis mediating SOCE is still only partially understood, as is the signal-coupling pathway leading to modulation of store-operated channels. This review emphasizes the role of calcium influx in the control of the NADPH oxidase and summarizes the current knowledge of pathways mediating this extracellular calcium entry in neutrophils. Such investigations into the cross-talk between NADPH oxidase and calcium might allow the identification of novel pharmacological targets with clinical use, particularly in inflammatory diseases.
Collapse
Affiliation(s)
- Sabrina Bréchard
- Life Sciences Research Unit, University of Luxembourg, Luxembourg.
| | | |
Collapse
|
104
|
Giesbert S, Schürg T, Scheele S, Tudzynski P. The NADPH oxidase Cpnox1 is required for full pathogenicity of the ergot fungus Claviceps purpurea. MOLECULAR PLANT PATHOLOGY 2008; 9:317-27. [PMID: 18705873 PMCID: PMC6640299 DOI: 10.1111/j.1364-3703.2008.00466.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The role of reactive oxygen species (ROS) in interactions between phytopathogenic fungi and their hosts is well established. An oxidative burst mainly caused by superoxide formation by membrane-associated NADPH oxidases is an essential element of plant defence reactions. Apart from primary effects, ROS play a major role as a second messenger in host response. Recently, NADPH oxidase (nox)-encoding genes have been identified in filamentous fungi. Functional analyses have shown that these fungal enzymes are involved in sexual differentiation, and there is growing evidence that they also affect developmental programmes involved in fungus-plant interactions. Here we show that in the biotrophic plant pathogen Claviceps purpurea deletion of the cpnox1 gene, probably encoding an NADPH oxidase, has impact on germination of conidia and pathogenicity: Deltacpnox1 mutants can penetrate the host epidermis, but they are impaired in colonization of the plant ovarian tissue. In the few cases where macroscopic signs of infection (honeydew) appear, they are extremely delayed and fully developed sclerotia have never been observed. C. purpurea Nox1 is important for the interaction with its host, probably by directly affecting pathogenic differentiation of the fungus.
Collapse
Affiliation(s)
- Sabine Giesbert
- Institut für Botanik, Westf. Wilhelms-Universität, Schlossgarten 3, D-48149 Münster, Germany
| | | | | | | |
Collapse
|
105
|
Nauseef WM. Nox enzymes in immune cells. Semin Immunopathol 2008; 30:195-208. [DOI: 10.1007/s00281-008-0117-4] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2008] [Accepted: 04/02/2008] [Indexed: 01/08/2023]
|
106
|
Tobar N, Cáceres M, Santibáñez JF, Smith PC, Martínez J. RAC1 activity and intracellular ROS modulate the migratory potential of MCF-7 cells through a NADPH oxidase and NFkappaB-dependent mechanism. Cancer Lett 2008; 267:125-32. [PMID: 18433991 DOI: 10.1016/j.canlet.2008.03.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2007] [Revised: 03/04/2008] [Accepted: 03/10/2008] [Indexed: 12/22/2022]
Abstract
In the present study, we demonstrated that changes in Rac1 activity associated with the production of intracellular ROS modulate the migratory properties in MCF-7 and T47D human mammary cell lines. We also described that the NFkappaB pathway exerts a downstream control on the expression of the ROS-dependent cellular migratory potential. These results emphasize the importance of redox balance in the acquisition of malignancy and support previous data sustaining that an oxidative environment predisposes cells to activate signal-transduction pathways actively involved in cellular oncogenesis. Our data also provides evidence that NADPH oxidase could constitute the main source of intracellular ROS in response to changes in Rac1 activity. We suggest that Rac1 plays a role in cellular migration not only limited to its known function in reorganization of the actin cytoskeleton, but also as part of the intracellular machinery that controls the redox balance.
Collapse
Affiliation(s)
- Nicolás Tobar
- Laboratorio de Biología Celular, INTA, Universidad de Chile, Casilla 138, Santiago 11, Chile
| | | | | | | | | |
Collapse
|
107
|
Affiliation(s)
- William M Nauseef
- Inflammation Program, Department of Medicine, University of Iowa and the Veterans Affairs Medical Center, Iowa City, Iowa 52241, USA.
| |
Collapse
|
108
|
Olsson LM, Lindqvist AK, Källberg H, Padyukov L, Burkhardt H, Alfredsson L, Klareskog L, Holmdahl R. A case-control study of rheumatoid arthritis identifies an associated single nucleotide polymorphism in the NCF4 gene, supporting a role for the NADPH-oxidase complex in autoimmunity. Arthritis Res Ther 2008; 9:R98. [PMID: 17897462 PMCID: PMC2212587 DOI: 10.1186/ar2299] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2007] [Revised: 09/17/2007] [Accepted: 09/26/2007] [Indexed: 01/20/2023] Open
Abstract
Rheumatoid arthritis (RA) is a chronic inflammatory disease with a heritability of 60%. Genetic contributions to RA are made by multiple genes, but only a few gene associations have yet been confirmed. By studying animal models, reduced capacity of the NADPH-oxidase (NOX) complex, caused by a single nucleotide polymorphism (SNP) in one of its components (the NCF1 gene), has been found to increase severity of arthritis. To our knowledge, however, no studies investigating the potential role played by reduced reactive oxygen species production in human RA have yet been reported. In order to examine the role played by the NOX complex in RA, we investigated the association of 51 SNPs in five genes of the NOX complex (CYBB, CYBA, NCF4, NCF2, and RAC2) in a Swedish case-control cohort consisting of 1,842 RA cases and 1,038 control individuals. Several SNPs were found to be mildly associated in men in NCF4 (rs729749, P = 0.001), NCF2 (rs789181, P = 0.02) and RAC2 (rs1476002, P = 0.05). No associations were detected in CYBA or CYBB. By stratifying for autoantibody status, we identified a strong association for rs729749 (in NCF4) in autoantibody negative disease, with the strongest association detected in rheumatoid factor negative men (CT genotype versus CC genotype: odds ratio 0.34, 95% confidence interval 0.2 to 0.6; P = 0.0001). To our knowledge, this is the first genetic association identified between RA and the NOX complex, and it supports previous findings from animal models of the importance of reactive oxygen species production capacity to the development of arthritis.
Collapse
Affiliation(s)
- Lina M Olsson
- Medical Inflammation Research, Lund University, BMC I11, 221 84, Lund, Sweden
| | - Anna-Karin Lindqvist
- Medical Inflammation Research, Lund University, BMC I11, 221 84, Lund, Sweden
- Cartela AB, Box 709, SE-220 07 Lund Sweden
| | - Henrik Källberg
- Institute for Environmental Medicine, Karolinska Institutet, Box 210, 171 77, Stockholm, Sweden
| | - Leonid Padyukov
- Rheumatology Unit, Department of Medicine, Karolinska Institutet, 171 76, Stockholm, Sweden
| | - Harald Burkhardt
- Division of rheumatology, Johann Wolfgang Goethe University, Theodor-Stern-Kai, 60596 Frankfurt am Main, Germany
| | - Lars Alfredsson
- Institute for Environmental Medicine, Karolinska Institutet, Box 210, 171 77, Stockholm, Sweden
| | - Lars Klareskog
- Rheumatology Unit, Department of Medicine, Karolinska Institutet, 171 76, Stockholm, Sweden
| | - Rikard Holmdahl
- Medical Inflammation Research, Lund University, BMC I11, 221 84, Lund, Sweden
| |
Collapse
|
109
|
Kao YY, Gianni D, Bohl B, Taylor RM, Bokoch GM. Identification of a conserved Rac-binding site on NADPH oxidases supports a direct GTPase regulatory mechanism. J Biol Chem 2008; 283:12736-46. [PMID: 18347018 DOI: 10.1074/jbc.m801010200] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The NADPH oxidases (Noxs) are a family of superoxide-generating enzymes implicated in a variety of biological processes. Full activity of Nox1, -2, and -3 requires the action of a Rac GTPase. A direct regulatory interaction of Rac with Nox2 has been proposed as part of a two-step mechanism for regulating electron transfer during superoxide formation. Using truncation analysis of Rac binding to the cytoplasmic tail of Nox2, along with peptides derived from this region in cell-free assays, we identify a Rac interaction site within amino acids 419-430 of Nox2. This region is required for binding Rac2 but not p47(phox) or p67(phox) cytosolic regulatory factors. A cell-permeant version of the peptide encompassing amino acids 419-430 specifically inhibits NADPH oxidase activation in intact human neutrophils. Mutational analysis of the putative Rac-binding site revealed specific residues, particularly Lys-421, Tyr-425, and Lys-426, individually required for Rac-dependent NADPH oxidase activity that are conserved in the Rac-regulated Nox1, Nox2, and Nox3 enzymes but not in Nox4 or Nox5. Mutation of the conserved residues in the Rac-binding site of Nox1 also result in the loss of Rac-dependent activity. Our data identify a functional Rac interaction site conserved in Rac-dependent Noxs and support a direct regulatory interaction of Rac GTPases to promote activation of these NADPH oxidases.
Collapse
Affiliation(s)
- Yu-Ya Kao
- Department of Immunology, The Scripps Research Institute, La Jolla, California 92037, USA
| | | | | | | | | |
Collapse
|
110
|
Han W, Li H, Villar VAM, Pascua AM, Dajani MI, Wang X, Natarajan A, Quinn MT, Felder RA, Jose PA, Yu P. Lipid rafts keep NADPH oxidase in the inactive state in human renal proximal tubule cells. Hypertension 2008; 51:481-7. [PMID: 18195159 DOI: 10.1161/hypertensionaha.107.103275] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Recent studies have indicated the importance of cholesterol-rich membrane lipid rafts (LRs) in oxidative stress-induced signal transduction. Reduced nicotinamide-adenine dinucleotide phosphate (NADPH) oxidases, the major sources of reactive oxygen species, are implicated in cardiovascular diseases, including hypertension. We tested the hypothesis that NADPH oxidase subunits and activity are regulated by LRs in human renal proximal tubule cells. We report that a high proportion of p22(phox) and the small GTPase Rac1 are expressed in LRs in human renal proximal tubule cells. The D(1)-like receptor agonist, fenoldopam (1 micromol/L per 20 minutes) dispersed Nox subunits within LRs and non-LRs and decreased oxidase activity (30.7+/-3.3%). In contrast, cholesterol depletion (2% methyl-beta-cyclodextrin [beta CD]) translocated NADPH oxidase subunits out of LRs and increased oxidase activity (154.0+/-10.5% versus control, 103.1+/-3.4%), which was reversed by cholesterol repletion (118.9+/-9.9%). Moreover, NADPH oxidase activation by beta CD (145.5+/-9.0%; control: 98.6+/-1.6%) was also abrogated by the NADPH oxidase inhibitors apocynin (100.4+/-3.2%) and diphenylene iodonium (9.5+/-3.3%). Furthermore, beta CD-induced reactive oxygen species production was reversed by knocking down either Nox2 (81.0+/-5.1% versus beta CD: 162.0+/-2.0%) or Nox4 (108.0+/-10.8% versus beta CD: 152.0+/-9.8%). We have demonstrated for the first time that disruption of LRs results in NADPH oxidase activation that is abolished by antioxidants and silencing of Nox2 or Nox4. Therefore, in human renal proximal tubule cells, LRs maintain NADPH oxidase in an inactive state.
Collapse
Affiliation(s)
- Weixing Han
- Department of Pediatrics, Georgetown University School of Medicine, Washington, DC, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
111
|
Chen PM, Chen HC, Ho CT, Jung CJ, Lien HT, Chen JY, Chia JS. The two-component system ScnRK of Streptococcus mutans affects hydrogen peroxide resistance and murine macrophage killing. Microbes Infect 2007; 10:293-301. [PMID: 18316220 DOI: 10.1016/j.micinf.2007.12.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2007] [Revised: 12/04/2007] [Accepted: 12/05/2007] [Indexed: 10/22/2022]
Abstract
To survive macrophage killing is critical in the pathogenesis of viridians streptococci-induced infective endocarditis (IE). Streptococcus mutans, an opportunistic IE pathogen, generally does not survive well phagocytic killing in murine macrophage RAW 264.7 cells. A putative two-component system (TCS), ScnR/ScnK from S. mutans, was investigated to elucidate the mechanisms underlying bacteria-cellular interaction in this study. Both the wild-type and mutant strains were phagocytosed by RAW 264.7 cells at a comparable rate and an increased intracellular susceptibility during a 5 h incubation period was observed with the scnRK-null mutants. The amount of reactive oxygen species (ROS) in activated macrophages was reduced significantly after ingesting wild-type, but not scnRK-null mutant strains, suggesting that increased macrophage killing of these mutants is due to the impaired ability of S. mutans to counteract ROS. Additionally, both scnR- or scnRK-null mutants were more susceptible to hydrogen peroxide. Interestingly, scnRK expression was unaffected by hydrogen peroxide. These experimental results indicate that scnRK is important in counteracting oxidative stress in S. mutans, and decreased susceptibility to phagocytic killing is at least partly attributable to inhibition of intracellular ROS formation.
Collapse
Affiliation(s)
- Pei-Min Chen
- Department and Graduate Institute of Microbiology, College of Medicine, National Taiwan University, No. 1, Jen Ai Road Section 1, Taipei 10051, Taiwan, ROC
| | | | | | | | | | | | | |
Collapse
|
112
|
Yi F, Chen QZ, Jin S, Li PL. Mechanism of homocysteine-induced Rac1/NADPH oxidase activation in mesangial cells: role of guanine nucleotide exchange factor Vav2. Cell Physiol Biochem 2007; 20:909-18. [PMID: 17982273 DOI: 10.1159/000110451] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/16/2007] [Indexed: 01/19/2023] Open
Abstract
We have demonstrated that homocysteine (Hcys) stimulates de novo ceramide synthesis and thereby induces NADPH oxidase activation by increase of Rac GTPase activity in rat mesangial cells (RMCs). However, which isofrom of Rac GTPases is involved in Hcys-induced NADPH oxidase activity and what mechanism mediates Hcys-induced Rac GTPase activation remain unknown. The present study first addressed the role of Rac1 and then determined the contribution of a subfamily of Guanine Nucleotide Exchange Factors (GEFs), Vav, to the action of Hcys on Rac and NADPH oxidase activities in RMCs. By small interfering RNA (siRNA), it was found that Rac1-siRNA attenuated Hcys-induced superoxide (O(2)(-)) production. To explore the mechanism activating Rac by Hcys, GEF-Vav was examined. Vav2 was found to be a predominant isoform among Vav family in RMCs. In Vav2-siRNA transfected RMCs, Hcys-induced Rac activity was blocked, which was accompanied by significant reduction of Hcys-induced O(2)(-). production. This Vav2-siRNA also blocked Rac activation induced by C16-Ceramide (C16-Cer), an intermediate lipid product stimulated by Hcys. Furthermore, we found that Hcys induced Vav2 phosphorylation in a time-dependent manner, which could be induced by C16-Cer and blocked by inhibition of de novo ceramide synthesis. These results suggest that Vav2 importantly contributes to Hcys-induced increase in Rac1 activity and consequent activation of NADPH oxidase in RMCs via ceramide-associated tyrosine phosphorylation.
Collapse
Affiliation(s)
- Fan Yi
- Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond, VA 23298, USA
| | | | | | | |
Collapse
|
113
|
Abstract
Like macrophages and neutrophils, dendritic cells (DCs) are considered professional phagocytes. Even if the three cell types phagocytose parasites, bacteria, cell debris, or even intact cells very efficiently, the functional outcomes of the phagocytic event are quite different. Macrophages and neutrophils scavenge and destroy phagocytosed particles, a critical step in innate immunity. DCs, in contrast, have developed means to 'preserve' useful information from the ingested particles that serve to initiate adaptive immune responses. Thus, both phagosomal degradation and acidification are much lower in DCs than in macrophages or neutrophils. Reduced degradation results in the conservation of antigenic peptides and in their increased presentation on major histocompatibility complex class I and II molecules. In this article, we review the mechanisms that control this delicate equilibrium between phagosomal degradation/cytotoxicity and antigen presentation in the different families of phagocytes.
Collapse
Affiliation(s)
- Ariel Savina
- Institut Curie, INSERM U653, Immunité et Cancer, Paris, France
| | | |
Collapse
|
114
|
|
115
|
Won JS, Singh AK, Singh I. Lactosylceramide: a lipid second messenger in neuroinflammatory disease. J Neurochem 2007; 103 Suppl 1:180-91. [DOI: 10.1111/j.1471-4159.2007.04822.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
|
116
|
Cooper SA, Whaley-Connell A, Habibi J, Wei Y, Lastra G, Manrique C, Stas S, Sowers JR. Renin-angiotensin-aldosterone system and oxidative stress in cardiovascular insulin resistance. Am J Physiol Heart Circ Physiol 2007; 293:H2009-23. [PMID: 17586614 DOI: 10.1152/ajpheart.00522.2007] [Citation(s) in RCA: 197] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Hypertension commonly occurs in conjunction with insulin resistance and other components of the cardiometabolic syndrome. Insulin resistance plays a significant role in the relationship between hypertension, Type 2 diabetes mellitus, chronic kidney disease, and cardiovascular disease. There is accumulating evidence that insulin resistance occurs in cardiovascular and renal tissue as well as in classical metabolic tissues (i.e., skeletal muscle, liver, and adipose tissue). Activation of the renin-angiotensin-aldosterone system and subsequent elevations in angiotensin II and aldosterone, as seen in cardiometabolic syndrome, contribute to altered insulin/IGF-1 signaling pathways and reactive oxygen species formation to induce endothelial dysfunction and cardiovascular disease. This review examines currently understood mechanisms underlying the development of resistance to the metabolic actions of insulin in cardiovascular as well as skeletal muscle tissue.
Collapse
Affiliation(s)
- Shawna A Cooper
- Department of Internal Medicine, University of Missouri School of Medicine, Columbia, Missouri 65212, USA
| | | | | | | | | | | | | | | |
Collapse
|
117
|
Usynin I, Klotz C, Frevert U. Malaria circumsporozoite protein inhibits the respiratory burst in Kupffer cells. Cell Microbiol 2007; 9:2610-28. [PMID: 17573905 DOI: 10.1111/j.1462-5822.2007.00982.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
After transmission by infected mosquitoes, malaria sporozoites rapidly travel to the liver. To infect hepatocytes, sporozoites traverse Kupffer cells, but surprisingly, the parasites are not killed by these resident macrophages of the liver. Here we show that Plasmodium sporozoites and recombinant circumsporozoite protein (CSP) suppress the respiratory burst in Kupffer cells. Sporozoites and CSP increased the intracellular concentration of cyclic adenosyl mono-phosphate (cAMP) and inositol 1,4,5-triphosphate in Kupffer cells, but not in hepatocytes or liver endothelia. Preincubation with cAMP analogues or inhibition of phosphodiesterase also inhibited the respiratory burst. By contrast, adenylyl cyclase inhibition abrogated the suppressive effect of sporozoites. Selective protein kinase A (PKA) inhibitors failed to reverse the CSP-mediated blockage and stimulation of the exchange protein directly activated by cAMP (EPAC), but not PKA inhibited the respiratory burst. Both blockage of the low-density lipoprotein receptor-related protein (LRP-1) with receptor-associated protein and elimination of cell surface proteoglycans inhibited the cAMP increase in Kupffer cells. We propose that by binding of CSP to LRP-1 and cell surface proteoglycans, malaria sporozoites induce a cAMP/EPAC-dependent, but PKA-independent signal transduction pathway that suppresses defence mechanisms in Kupffer cells. This allows the sporozoites to safely pass through these professional phagocytes and to develop inside neighbouring hepatocytes.
Collapse
Affiliation(s)
- Ivan Usynin
- Department of Medical Parasitology, New York University School of Medicine, 341 E 25 St, New York, NY 10010, USA
| | | | | |
Collapse
|
118
|
Seres I, Fóris G, Varga Z, Kosztáczky B, Kassai A, Balogh Z, Fülöp P, Paragh G. The association between angiotensin II-induced free radical generation and membrane fluidity in neutrophils of patients with metabolic syndrome. J Membr Biol 2007; 214:91-8. [PMID: 17546512 DOI: 10.1007/s00232-006-0020-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2006] [Revised: 11/09/2006] [Indexed: 11/26/2022]
Abstract
Angiotensin II (Ang II) is able to induce free radical generation in neutrophils, which is more elevated in neutrophils of patients with hypercholesterolemia (HC). In addition, the signal processing through angiotensin I (Ang I) receptors is altered. In present study, we compared the Ang II-triggered free radical generation of neutrophils obtained from patients with relatively isolated forms of metabolic syndrome (MS) with membrane-bound cholesterol content and membrane fluidity. We determined the enhancement of Ang II-induced superoxide anion and leukotriene C(4) (LTC(4)) generation, membrane fluidity and cell-bound cholesterol content of neutrophils obtained from 12 control subjects, 11 patients with obesity (Ob), 10 patients with type 2 diabetes mellitus (t2-DM) and 12 patients with HC. The alteration of signal processing was studied after preincubation with different inhibiting drugs. Superoxide anion, LTC(4) production and membrane rigidity were increased in the following order: control < Ob < t2-DM < HC. Both Ang II-induced superoxide anion and LTC(4) generation were decreased in control cells by pertussis toxin and fluvastatin (Flu), whereas in each patient group, mepacrin, verapamil and Flu were effective, suggesting alterations in signal pathways, which may be attributed to isoprenylation. The enhancement of superoxide anion and LTC(4) generation correlated significantly with membrane rigidity, independently from the experimental groups and membrane-bound cholesterol content. Membrane rigidity of neutrophils, obtained from patients with MS, plays a role in Ang II-induced free radical generation independent of intracellular cholesterol homeostasis.
Collapse
Affiliation(s)
- Ildikó Seres
- First Department of Medicine, Medical and Health Science Center, University of Debrecen, Nagyerdei krt. 98, Debrecen, H-4012 Hungary
| | | | | | | | | | | | | | | |
Collapse
|
119
|
Reinehr R, Görg B, Becker S, Qvartskhava N, Bidmon HJ, Selbach O, Haas HL, Schliess F, Häussinger D. Hypoosmotic swelling and ammonia increase oxidative stress by NADPH oxidase in cultured astrocytes and vital brain slices. Glia 2007; 55:758-71. [PMID: 17352382 DOI: 10.1002/glia.20504] [Citation(s) in RCA: 160] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The role of NADPH oxidase (NOX) and the regulatory subunit p47(phox) for hypoosmotic ROS generation was studied in cultured rat astrocytes and brain slices of wilde type and p47(phox) knock-out mice. Cultured rat astrocytes express mRNAs encoding for the regulatory subunit p47(phox), NOX1, 2, and 4, and the dual oxidases (DUOX)1 and 2, but not NOX3. Hypoosmotic (205 mosmol/L) swelling of cultured astrocytes induced a rapid generation of ROS that was accompanied by serine phosphorylation of p47(phox) and prevented by the NADPH oxidase inhibitor apocynin. Apocynin also impaired the hypoosmotic tyrosine phosphorylation of Src. Both, hypoosmotic ROS generation and p47(phox) serine phosphorylation were sensitive to the acidic sphingomyelinase inhibitors AY9944 and desipramine, the protein kinase C (PKC)zeta-inhibitory pseudosubstrate peptide, the NMDA receptor antagonist MK-801 and the intracellular Ca(2+) chelator BAPTA-AM. Also hypoosmotic exposure of wilde type mouse cortical brain slices increased ROS generation, which was allocated in part to the astrocytes and which was absent in presence of apocynin and in cortical brain slices from p47(phox) knock-out mice. Also ammonia induced a rapid ROS production in cultured astrocytes and brain slices, which was sensitive to apocynin. The data suggest that astrocyte swelling triggers a p47(phox)-dependent NADPH oxidase-catalyzed ROS production. The findings further support a close interrelation between osmotic and oxidative stress in astrocytes, which may be relevant to different brain pathologies including hepatic encephalopathy.
Collapse
Affiliation(s)
- Roland Reinehr
- Clinic for Gastroenterology, Hepatology and Infectiology, Heinrich Heine University, Moorenstrasse 5, D-40225 Düsseldorf, Germany
| | | | | | | | | | | | | | | | | |
Collapse
|
120
|
Kosztáczky B, Fóris G, Paragh G, Seres I, Zsiros E, Koncsos P, Balogh Z, Paragh G. Leptin stimulates endogenous cholesterol synthesis in human monocytes: New role of an old player in atherosclerotic plaque formation. Leptin-induced increase in cholesterol synthesis. Int J Biochem Cell Biol 2007; 39:1637-45. [PMID: 17560160 DOI: 10.1016/j.biocel.2007.04.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2006] [Revised: 04/11/2007] [Accepted: 04/13/2007] [Indexed: 11/17/2022]
Abstract
The role of leptin in the pathomechanism of atherosclerosis, through its free radical generating ability is established. Its effect however, on the regulation of intracellular cholesterol synthesis has not been studied. The aim of the present study was to elucidate whether leptin influences endogenous cholesterol synthesis in monocytes. Furthermore, leptin signaling to HMG CoA reductase in control and hypercholesterolemic monocytes were compared. The in vitro effect of leptin was studied on freshly isolated human monocytes obtained from healthy control volunteers and patients with hypercholesterolemia. Our results can be summarized as follows: (1) Leptin is able to increase endogenous cholesterol synthesis in human monocytes in vitro. (2) The cholesterol synthesis increasing effect of the hormone is more pronounced in hypercholesterolemic monocytes with high basal cholesterol biosynthesis. (3) The leptin-induced Ca(2+) signal was involved in the enhancement of HMG CoA reductase activation in monocytes from both controls and hypercholesterolemic patients. (4) In control monocytes the Ca(2+) signal originated from intracellular pools, whereas in patients, Ca(2+)-influx and protein kinase C activation were found to be responsible for the leptin-effect. Mevalonate cycle inhibiting fluvastatin and 25-hydroxycholesterol decreased cholesterol production in leptin-stimulated monocytes. Our present study provides the first proof of the cholesterol synthesis enhancing effect of leptin through a statin-sensitive pathway in circulating monocytes. Furthermore our results suggest that leptin can be involved in the pathomechanism of atherosclerotic plaque formation also through its effect on cholesterol biosynthesis in monocytes.
Collapse
Affiliation(s)
- Béla Kosztáczky
- First Department of Medicine, Medical and Health Science Center, University of Debrecen, Nagyerdei krt. 98, Debrecen H-4012, Hungary
| | | | | | | | | | | | | | | |
Collapse
|
121
|
Kaneyuki U, Ueda S, Yamagishi SI, Kato S, Fujimura T, Shibata R, Hayashida A, Yoshimura J, Kojiro M, Oshima K, Okuda S. Pitavastatin inhibits lysophosphatidic acid-induced proliferation and monocyte chemoattractant protein-1 expression in aortic smooth muscle cells by suppressing Rac-1-mediated reactive oxygen species generation. Vascul Pharmacol 2007; 46:286-92. [PMID: 17178255 DOI: 10.1016/j.vph.2006.11.002] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2006] [Revised: 11/07/2006] [Accepted: 11/07/2006] [Indexed: 12/29/2022]
Abstract
Lysophosphatidic acid (LPA), a product generated during oxidative modification of low-density lipoprotein (LDL) and a major lipid extracted from human atherosclerotic plaques, has been shown to elicit smooth muscle cell (SMC) proliferation and inflammation, thereby being involved in atherogenesis. Recently, statins, an inhibitor of 3-hydroxy-methylglutaryl coenzyme A (HMG-CoA) reductase, have been reported to reduce the risk of cardiovascular events and slows the progression of atherosclerosis, at least partly, via pleiotropic effects. However, the effect of statin on the LPA-signaling in SMCs remains to be elucidated. In this study, we investigated whether and how pitavastatin could inhibit the LPA-induced proliferation and monocyte chemoattractant protein-1 (MCP-1) expression in cultured human aortic SMCs. LPA dose-dependently increased intracellular reactive oxygen species (ROS) generation in SMCs, which was blocked by diphenylene iodonium (DPI), an inhibitor of NADPH oxidase or pitavastatin. The anti-oxidative property of pitavastatin was prevented by simultaneous treatment of geranylgeranyl pyrophosphate. Furthermore, overexpression of dominant negative Rac-1 mutant was found to inhibit the LPA-induced ROS generation in SMCs. LPA induced Rac-1 activation in SMCs, which was suppressed by pitavastatin or LPA receptor antagonist. Pitavastatin, DPI, and an anti-oxidant N-acetylcysteine inhibited the LPA-induced proliferation and MCP-1 gene expression in SMCs. These results suggest that pitavastatin could block the LPA-induced proliferation and MCP-1 expression in SMCs by suppressing Rac-1-mediated NADPH oxidase-dependent ROS generation. Our present study provides a novel beneficial aspect of pitavastatin; pitavastatin may act as a blocker of the LPA-signaling in SMCs.
Collapse
MESH Headings
- Antioxidants/pharmacology
- Aorta/drug effects
- Aorta/metabolism
- Cell Proliferation/drug effects
- Cells, Cultured
- Chemokine CCL2/metabolism
- Dose-Response Relationship, Drug
- Gene Expression/drug effects
- Humans
- Hydroxymethylglutaryl-CoA Reductase Inhibitors/pharmacology
- Lysophospholipids/pharmacology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Myocytes, Smooth Muscle/drug effects
- Myocytes, Smooth Muscle/metabolism
- NADPH Oxidases/metabolism
- Quinolines/pharmacology
- RNA, Messenger/metabolism
- Reactive Oxygen Species/metabolism
- Receptors, Lysophosphatidic Acid/drug effects
- Signal Transduction/drug effects
- Transfection
- rac1 GTP-Binding Protein/metabolism
Collapse
Affiliation(s)
- Utako Kaneyuki
- Division of Nephrology, Department of Medicine, Kurume University School of Medicine, 67 Asahi-machi, Kurume, 830-0011, Japan
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
122
|
Abstract
Reactive oxygen species (ROS) are recently proposed to be involved in tumor metastasis which is a complicated processes including epithelial-mesenchymal transition (EMT), migration, invasion of the tumor cells and angiogenesis around the tumor lesion. ROS generation may be induced intracellularly, in either NADPH oxidase- or mitochondria-dependent manner, by growth factors and cytokines (such as TGFbeta and HGF) and tumor promoters (such as TPA) capable of triggering cell adhesion, EMT and migration. As a signaling messenger, ROS are able to oxidize the critical target molecules such as PKC and protein tyrosine phosphates (PTPs), which are relevant to tumor cell invasion. PKC contain multiple cysteine residues that can be oxidized and activated by ROS. Inactivation of multiple PTPs by ROS may relieve the tyrosine phosphorylation-dependent signaling. Two of the down-stream molecules regulated by ROS are MAPK and PAK. MAPKs cascades were established to be a major signal pathway for driving tumor cell metastasis, which are mediated by PKC, TGF-beta/Smad and integrin-mediated signaling. PAK is an effector of Rac-mediated cytoskeletal remodeling that is responsible for cell migration and angiogenesis. There are several transcriptional factors such as AP1, Ets, Smad and Snail regulating a lot of genes relevant to metastasis. AP-1 and Smad can be activated by PKC activator and TGF-beta1, respectively, in a ROS dependent manner. On the other hand, Est-1 can be upregulated by H2O2 via an antioxidant response element in the promoter. The ROS-regulated genes relevant to EMT and metastasis include E-cahedrin, integrin and MMP. Comprehensive understanding of the ROS-triggered signaling transduction, transcriptional activation and regulation of gene expressions will help strengthen the critical role of ROS in tumor progression and devising strategy for chemo-therapeutic interventions.
Collapse
Affiliation(s)
- Wen-Sheng Wu
- Department of Medical Technology, Tzu Chi University, No. 701, Chung Yang Rd, Sec 3, Hualien 970, Taiwan.
| |
Collapse
|
123
|
Chen X, Abair TD, Ibanez MR, Su Y, Frey MR, Dise RS, Polk DB, Singh AB, Harris RC, Zent R, Pozzi A. Integrin alpha1beta1 controls reactive oxygen species synthesis by negatively regulating epidermal growth factor receptor-mediated Rac activation. Mol Cell Biol 2007; 27:3313-26. [PMID: 17339338 PMCID: PMC1899972 DOI: 10.1128/mcb.01476-06] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Integrins control many cell functions, including generation of reactive oxygen species (ROS) and regulation of collagen synthesis. Mesangial cells, found in the glomerulus of the kidney, are able to produce large amounts of ROS via the NADPH oxidase. We previously demonstrated that integrin alpha1-null mice develop worse fibrosis than wild-type mice following glomerular injury and this is due, in part, to excessive ROS production by alpha1-null mesangial cells. In the present studies, we describe the mechanism whereby integrin alpha1-null mesangial cells produce excessive ROS. Integrin alpha1-null mesangial cells have constitutively increased basal levels of activated Rac1, which result in its increased translocation to the cell membrane, excessive ROS production, and consequent collagen IV deposition. Basal Rac1 activation is a direct consequence of ligand-independent increased epidermal growth factor receptor (EGFR) phosphorylation in alpha1-null mesangial cells. Thus, our study demonstrates that integrin alpha1beta1-EGFR cross talk is a key step in negatively regulating Rac1 activation, ROS production, and excessive collagen synthesis, which is a hallmark of diseases characterized by irreversible fibrosis.
Collapse
Affiliation(s)
- Xiwu Chen
- Department of Medicine, Division of Nephrology, Vanderbilt University, Nashville, TN 37232, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
124
|
Rodríguez AA, Ramiro Lascano H, Bustos D, Taleisnik E. Salinity-induced decrease in NADPH oxidase activity in the maize leaf blade elongation zone. JOURNAL OF PLANT PHYSIOLOGY 2007; 164:223-30. [PMID: 17074408 DOI: 10.1016/j.jplph.2006.07.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2006] [Accepted: 07/03/2006] [Indexed: 05/12/2023]
Abstract
We reported previously that salinity-induced elongation constraints in the expansion zone of maize leaves are associated with reduced reactive oxygen species (ROS) production and could be alleviated by the addition of ROS. The NaCl effect was salt-specific and not osmotic. This paper explores the causes for such reduction. The decrease in ROS levels under salinity was not accompanied by increases in soluble apoplastic antioxidant activities such as superoxide dismutase, peroxidases and ascorbate. In experimental systems devoid of cell walls (protoplasts and membrane fractions) superoxide anion (O(2)(-)) production was inhibited by 50 and 100 mM NaCl, 50 microM DPI, 10 mM EGTA, and 5mM verapamil, a Ca(2+) channel inhibitor. Inhibitory effects of NaCl and reduced Ca(2+) supply were also observed in in gel assessment of O(2)(-) -generating activity. The main activity band excised from the ND-PAGE was recognized by an antibody against the C-terminal portion of the tomato gp91(phox) homolog. These results indicate the *O(2)(-) -generating activity negatively affected by NaCl was compatible with that of plasma membrane NADPH oxidase.
Collapse
|
125
|
Sagara Y, Hirooka Y, Nozoe M, Ito K, Kimura Y, Sunagawa K. Pressor response induced by central angiotensin II is mediated by activation of Rho/Rho-kinase pathway via AT1 receptors. J Hypertens 2007; 25:399-406. [PMID: 17211247 DOI: 10.1097/hjh.0b013e328010b87f] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES The brain renin-angiotensin system plays an important role in cardiovascular regulation and the pathogenesis of hypertension. Angiotensin II activates the Rho/Rho-kinase pathway in vascular smooth muscle cells and cardiomyocytes in vitro. The aim of the present study was to determine whether angiotensin II in the brainstem activates the Rho/Rho-kinase pathway, and, if so, whether this mechanism is involved in the central pressor action of angiotensin II. METHODS AND RESULTS Angiotensin II infused intracisternally for 7 days in Wistar-Kyoto rats (WKY) increased systolic blood pressure (SBP) and urinary norepinephrine excretion. These responses were abolished by the co-infusion of Y-27632, a specific Rho-kinase inhibitor, or valsartan. The intracisternal infusion of Y-27632 or valsartan also reduced SBP and norepinephrine excretion in spontaneously hypertensive rats (SHR). Western blot analysis was performed to examine the expression levels of membranous RhoA and phosphorylated ezrin, radixin, and moesin (p-ERM), which reflects Rho/Rho-kinase activity. The expression levels of membranous RhoA and p-ERM in the brainstem were significantly greater in both angiotensin II-treated WKY and SHR than in vehicle-treated WKY. Valsartan reduced the expression levels of membranous RhoA and p-ERM in angiotensin II-treated WKY and SHR. Y-27632 reduced the expression levels of p-ERM in angiotensin II-treated WKY and SHR. CONCLUSIONS These results suggest that the pressor response induced by intracisternally infused angiotensin II is substantially mediated by the activation of the Rho/Rho-kinase pathway via AT1 receptors of the brainstem in WKY, and that this pathway might be involved in the hypertensive mechanisms of SHR.
Collapse
Affiliation(s)
- Yoji Sagara
- Department of Cardiovascular Medicine, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
| | | | | | | | | | | |
Collapse
|
126
|
Bedard K, Krause KH. The NOX family of ROS-generating NADPH oxidases: physiology and pathophysiology. Physiol Rev 2007; 87:245-313. [PMID: 17237347 DOI: 10.1152/physrev.00044.2005] [Citation(s) in RCA: 4890] [Impact Index Per Article: 287.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
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/gp91(phox)), 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 activity 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.
Collapse
Affiliation(s)
- Karen Bedard
- Biology of Ageing Laboratories, University of Geneva, Geneva, Switzerland
| | | |
Collapse
|
127
|
Cacciapuoti C, Terrazzano G, Barone L, Sica M, Becchimanzi C, Rotoli B, Ruggiero G, Alfinito F. Glycosyl-phosphatidyl-inositol-defective granulocytes from paroxysmal nocturnal haemoglobinuria patients show increased bacterial ingestion but reduced respiratory burst induction. Am J Hematol 2007; 82:98-107. [PMID: 17013814 DOI: 10.1002/ajh.20779] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Paroxysmal nocturnal hemoglobinuria (PNH) is characterized by the emergence of a GPI-defective clonal hematopoiesis. Its clinical features are hemolytic anemia, cytopenia, and thrombosis. Circulating monocytes and granulocytes are largely GPI-defective in PNH patients. This study aims to investigate the granulocyte functional properties in PNH. We analyzed bacterial-dependent intracellular ingestion and the consequent activation of oxidative burst in GPI-defective granulocytes from four neutropenic PNH patients. Our data show a significant increase in the ability of GPI-defective granulocytes to ingest opsonized bacteria. In addition, an impaired respiratory burst effectiveness in response to two independent bacterial stimuli, the N-formyl-MetLeuPhe (fMLP) synthetic bacterial peptide and E. coli, was revealed. The occurrence of neutropenia and the severe impairment of oxidative burst, occurring in chronic granulomatosis disease, were unable to significantly affect phagocytosis. Thus, additional mechanisms, able to differentially affect ingestion ability and respiratory burst effectiveness, have to be hypothesized. The reduced burst effectiveness of GPI-defective granulocytes was maintained after treatment with phorbol 12-myristate 13-acetate, a pharmacological stimulus able to extensively recruit and to trigger intracellular protein kinase C (PKC). Moreover, blocking of PKC has been observed to severely affect granulocyte respiratory burst with a mild effect on the phagocytosis. These data suggest a role for a modulation of intracellular PKC in the pathogenesis of the impaired granulocyte oxidative burst.
Collapse
Affiliation(s)
- Carmela Cacciapuoti
- Dipartimento di Biologia e Patologia Cellulare e Molecolare, Università di Napoli Federico II, Naples, Italy
| | | | | | | | | | | | | | | |
Collapse
|
128
|
Ueyama T, Tatsuno T, Kawasaki T, Tsujibe S, Shirai Y, Sumimoto H, Leto TL, Saito N. A regulated adaptor function of p40phox: distinct p67phox membrane targeting by p40phox and by p47phox. Mol Biol Cell 2007; 18:441-54. [PMID: 17122360 PMCID: PMC1783789 DOI: 10.1091/mbc.e06-08-0731] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2006] [Revised: 11/13/2006] [Accepted: 11/14/2006] [Indexed: 11/11/2022] Open
Abstract
In the phagocytic cell, NADPH oxidase (Nox2) system, cytoplasmic regulators (p47(phox), p67(phox), p40(phox), and Rac) translocate and associate with the membrane-spanning flavocytochrome b(558), leading to activation of superoxide production. We examined membrane targeting of phox proteins and explored conformational changes in p40(phox) that regulate its translocation to membranes upon stimulation. GFP-p40(phox) translocates to early endosomes, whereas GFP-p47(phox) translocates to the plasma membrane in response to arachidonic acid. In contrast, GFP-p67(phox) does not translocate to membranes when expressed alone, but it is dependent on p40(phox) and p47(phox) for its translocation to early endosomes or the plasma membrane, respectively. Translocation of GFP-p40(phox) or GFP-p47(phox) to their respective membrane-targeting sites is abolished by mutations in their phox (PX) domains that disrupt their interactions with their cognate phospholipid ligands. Furthermore, GFP-p67(phox) translocation to either membrane is abolished by mutations that disrupt its interaction with p40(phox) or p47(phox). Finally, we detected a head-to-tail (PX-Phox and Bem1 [PB1] domain) intramolecular interaction within p40(phox) in its resting state by deletion mutagenesis, cell localization, and binding experiments, suggesting that its PX domain is inaccessible to interact with phosphatidylinositol 3-phosphate without cell stimulation. Thus, both p40(phox) and p47(phox) function as diverse p67(phox) "carrier proteins" regulated by the unmasking of membrane-targeting domains in distinct mechanisms.
Collapse
Affiliation(s)
- Takehiko Ueyama
- *Laboratory of Molecular Pharmacology, Biosignal Research Center, Kobe University, Kobe 657-8501, Japan
| | - Toshihiko Tatsuno
- *Laboratory of Molecular Pharmacology, Biosignal Research Center, Kobe University, Kobe 657-8501, Japan
| | - Takumi Kawasaki
- *Laboratory of Molecular Pharmacology, Biosignal Research Center, Kobe University, Kobe 657-8501, Japan
| | - Satoshi Tsujibe
- *Laboratory of Molecular Pharmacology, Biosignal Research Center, Kobe University, Kobe 657-8501, Japan
| | - Yasuhito Shirai
- *Laboratory of Molecular Pharmacology, Biosignal Research Center, Kobe University, Kobe 657-8501, Japan
| | - Hideki Sumimoto
- Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582, Japan
| | - Thomas L. Leto
- Molecular Defenses Section, Laboratory of Host Defenses, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892; and
| | - Naoaki Saito
- *Laboratory of Molecular Pharmacology, Biosignal Research Center, Kobe University, Kobe 657-8501, Japan
| |
Collapse
|
129
|
Reinehr R, Häussinger D. CD95 activation in the liver: ion fluxes and oxidative signaling. Arch Biochem Biophys 2007; 462:124-31. [PMID: 17258167 DOI: 10.1016/j.abb.2006.12.019] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2006] [Revised: 12/14/2006] [Accepted: 12/16/2006] [Indexed: 12/18/2022]
Abstract
Apoptosis is characterized by typical features as cell shrinkage, nuclear condensation, DNA fragmentation, and apoptotic body formation. Whereas some signs of apoptosis are cell type-and death signal-dependent, apoptotic cell volume decrease is an early and ubiquitous event and little is known about the signalling events, which are localized upstream of the plasma membrane transport steps leading to apoptotic cell volume decrease and the proapoptotic events, which are induced by osmolyte loss and cell shrinkage. Ion fluxes and oxidative signaling were recently shown to play an important role in signal transduction with respect to apoptotic cell death within the liver, as a ceramide-dependent activation of the NADPH oxidase was identified as the source of reactive oxygen species generation in rat hepatocytes upon treatment with CD95 ligand, hydrophobic bile salts or hyperosmolarity. The NADPH oxidase-derived ROS signal then allows via Yes, JNK, and EGFR activation for CD95 tyrosine phosphorylation as a prerequisite for CD95 targeting to the plasma membrane and formation of the death inducing signalling complex. Other covalent modifications such as CD95-tyrosine-nitration or CD95-serine/threonine-phosphorylation can interfere with the CD95 activation process. The findings not only provide a mechanistic explanation for the high susceptibility of dehydrated cells for apoptosis, but also give insight into the role of ion fluxes and oxidative signaling with respect to apoptotic cell death within the liver.
Collapse
Affiliation(s)
- Roland Reinehr
- Clinic for Gastroenterology, Hepatology and Infectiology, Heinrich-Heine-University, Düsseldorf, Germany
| | | |
Collapse
|
130
|
Whaley-Connell AT, Morris EM, Rehmer N, Yaghoubian JC, Wei Y, Hayden MR, Habibi J, Stump CS, Sowers JR. Albumin activation of NAD(P)H oxidase activity is mediated via Rac1 in proximal tubule cells. Am J Nephrol 2007; 27:15-23. [PMID: 17204833 DOI: 10.1159/000098432] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2006] [Accepted: 11/30/2006] [Indexed: 11/19/2022]
Abstract
BACKGROUND Rac1 is a Rho-family small GTP-ase, when activated is pivotal in NAD(P)H oxidase (NOX) activation and generation of reactive oxygen species (ROS). Evidence links Rac1 activation to receptor-mediated albumin endocytosis in the proximal tubule cell (PTC). Thus in states of albumin overload, Rac1 activation could lead to NOX activation and ROS formation in the PTC. Furthermore, accumulating evidence supports that HMG-CoA reductase inhibition may reduce oxidative stress and albuminuria. METHODS To investigate the role of HMG-CoA reductase inhibition of Rac1 and oxidative stress we used the opossum kidney PTC. ROS generation in the PTC was confirmed using oxidative fluorescent dihydroethidium staining. RESULTS We observed time-dependent increases in NOX activity with bovine serum albumin (albumin) stimulation (500 microg/dl, maximum at 20 min, p < 0.05) that was inhibited in a concentration-dependent manner with the HMG-CoA reductase inhibitor rosuvastatin (1 microM, p < 0.05). Additionally, the Rac1 inhibitor NSC23766 (100 ng/ml) attenuated albumin activation of NOX. Western blot analysis confirmed Rac1 translocation to plasma membrane in the PTC following albumin stimulation and subsequent inhibition by rosuvastatin and NSC23766. CONCLUSIONS These data demonstrate that albumin-mediated increases in NOX activity and ROS in PTC are reversed by inhibition of Rac1 signaling with the use of rosuvastatin.
Collapse
Affiliation(s)
- Adam T Whaley-Connell
- Department of Internal Medicine, University of Missouri School of Medicine, Columbia, MO 65212, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
131
|
Molshanski-Mor S, Mizrahi A, Ugolev Y, Dahan I, Berdichevsky Y, Pick E. Cell-free assays: the reductionist approach to the study of NADPH oxidase assembly, or "all you wanted to know about cell-free assays but did not dare to ask". Methods Mol Biol 2007; 412:385-428. [PMID: 18453125 DOI: 10.1007/978-1-59745-467-4_25] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The superoxide (O2-)-generating enzyme complex of phagocytes, known as the NADPH oxidase, can be assayed in a number of in vitro cell-free (or broken cell) systems. These consist of a mixture of the individual components of the NADPH oxidase, derived from resting phagocytes or in the form of purified recombinant proteins, exposed to an activating agent (or situation), in the presence of NADPH and oxygen. O2- produced by the mixture is measured by being trapped immediately after its generation with an appropriate acceptor in a kinetic assay, which permits the calculation of the linear rate of O2- production over time. Cell-free assays are distinguished from whole-cell assays or assays performed on membranes derived from stimulated cells by the fact that all components in the reaction are derived from resting, nonstimulated cells and, thus, the steps of NADPH oxidase activation (precatalytic [assembly] and catalytic) occur in vitro. Cell-free assays played a paramount role in the identification of the components of the NADPH oxidase complex, the diagnosis of various forms of chronic granulomatous disease (CGD), and, more recently, the analysis of the domains present on the components of the NADPH oxidase participating in protein-protein interactions leading to the assembly of the active complex.
Collapse
Affiliation(s)
- Shahar Molshanski-Mor
- The Julius Friedrich Cohnheim-Minerva Center for Phagocyte Research, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | | | | | | | | | | |
Collapse
|
132
|
Chang EJ, Kim HJ, Ha J, Kim HJ, Ryu J, Park KH, Kim UH, Lee ZH, Kim HM, Fisher DE, Kim HH. Hyaluronan inhibits osteoclast differentiation via Toll-like receptor 4. J Cell Sci 2007; 120:166-76. [PMID: 17164294 DOI: 10.1242/jcs.03310] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The differentiation of osteoclasts, cells specialized for bone resorption, is governed by two key factors, macrophage colony stimulating factor (M-CSF) and receptor activator of nuclear factor κB ligand (RANKL). The extracellular matrix (ECM) is an important factor influencing cell fate. To date, little investigation on the relationship between ECM components and osteoclast differentiation has been documented. In this study, we uncovered a potent anti-osteoclastogenic effect of hyaluronan (HA), an ECM component present in bone marrow and soft connective tissues, in primary mouse and human osteoclast precursor cell cultures. The anti-osteoclastogenic function of HA was dependent on Toll-like receptor 4 (TLR4) but not on CD44. HA inhibited M-CSF-dependent signaling pathways involving Rac, reactive oxygen species and mitogen-activated protein kinases, resulting in suppression of transcription factors AP-1 and MITF that control RANK expression. Furthermore, in an in vivo mouse model of calvarial bone resorption assays HA reduced RANKL-induced bone erosion and osteoclastogenesis. Our results clearly show that HA inhibits osteoclast differentiation through TLR4 by interfering with M-CSF signaling, and point that the interaction between ECM components and innate immune receptors can play an important role in the regulation of bone metabolism.
Collapse
Affiliation(s)
- Eun-Ju Chang
- Department of Cell and Developmental Biology and Brain Korea 21 Program, DRI, Seoul National University, Seoul 110-749, Korea
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
133
|
Abstract
Cell shrinkage, nuclear condensation, DNA fragmentation, and apoptotic body formation are hallmarks of programmed apoptotic cell death. Herein, apoptotic volume decrease (AVD) is an early and ubiquitous event. Conversely, in hepatocytes, hyperosmotic cell shrinkage leads to an activation of the CD95 death receptor system, which involves CD95 tyrosine phosphorylation, CD95 oligomerization, and subsequent trafficking of the CD95 to the plasma membrane, and sensitizes hepatocytes toward CD95 ligand (CD95L)-induced apoptosis. Early signaling events leading to CD95 activation by hyperosmolarity have been identified. In hepatocytes, hyperosmotic exposure induces an almost instantaneous acidification of an acidic sphingomyelinase (ASM) containing endosomal compartment, which is followed by an increase in the intracellular ceramide concentration. Inhibition of anion channels or the vacuolar-type H(+)-ATPase abolishes not only endosomal acidification and subsequent ceramide generation, but also the otherwise observed hyperosmotically induced generation of reactive oxygen species (ROS) by NADPH oxidase isoforms. Hyperosmolarity-induced ROS formation then leads to a Src-family kinase Yes-mediated activation of the epidermal growth factor receptor (EGFR) and to an activation of the c-Jun-N-terminal kinase (JNK). JNK then provides a signal for CD95/EGFR association and subsequent CD95 tyrosine phosphorylation, which is mediated by the EGFR tyrosine kinase activity. CD95 tyrosine phosphorylation then allows for CD95 receptor oligomerization, translocation of the CD95/EGFR protein complex to the plasma membrane, and formation of the death inducing signaling complex (DISC). Mild hyperosmotic exposure, that is, 405 mosmol/liter, does not lead to a reduction of cell viability, even if DISC formation and subsequent caspase 8 and 3 activation occur, but sensitizes hepatocytes to CD95L-induced apoptosis. However, activation of the CD95 system by a more severe hyperosmotic challenge (>505 mosmol/liter) is followed by execution of the apoptotic cell death. Other covalent modifications of CD95, such as CD95 tyrosine nitration or CD95 serine/threonine phosphorylation, were shown to inhibit the CD95 activation process.
Collapse
Affiliation(s)
- Roland Reinehr
- Clinic for Gastroenterology, Hepatology, and Infectiology, Heinrich-Heine-University Düsseldorf, Germany
| | | |
Collapse
|
134
|
Gao XP, Zhu X, Fu J, Liu Q, Frey RS, Malik AB. Blockade of class IA phosphoinositide 3-kinase in neutrophils prevents NADPH oxidase activation- and adhesion-dependent inflammation. J Biol Chem 2006; 282:6116-25. [PMID: 17197441 DOI: 10.1074/jbc.m610248200] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We examined the role of class IA phosphoinositide 3-kinase (PI3K) in the regulation of activation of NADPH oxidase in PMNs and the mechanism of PMN-dependent lung inflammation and microvessel injury induced by the pro-inflammatory cytokine TNF-alpha. TNF-alpha stimulation of PMNs resulted in superoxide production that was dependent on CD11b/CD18-mediated PMN adhesion. Additionally, TNF-alpha induced the association of CD11b/CD18 with the NADPH oxidase subunit Nox2 (gp91(phox)) and phosphorylation of p47(phox), indicating the CD11b/CD18 dependence of NADPH oxidase activation. Transduction of wild-type PMNs with Deltap85 protein, a dominant-negative form of the class IA PI3K regulatory subunit, p85alpha, fused to HIV-TAT (TAT-Deltap85) prevented (i) CD11b/CD18-dependent PMN adhesion, (ii) interaction of CD11b/CD18 with Nox2 and phosphorylation of p47(phox), and (iii) PMN oxidant production. Furthermore, studies in mice showed that i.v. infusion of TAT-Deltap85 significantly reduced the recruitment of PMNs in lungs and increase in lung microvascular permeability induced by TNF-alpha. We conclude that class IA PI3K serves as a nodal point regulating CD11b/CD18-integrin-dependent PMN adhesion and activation of NADPH oxidase, and leads to oxidant production at sites of PMN adhesion, and the resultant lung microvascular injury in mice.
Collapse
Affiliation(s)
- Xiao-Pei Gao
- Department of Pharmacology and Center of Lung and Vascular Biology, University of Illinois College of Medicine, Chicago, Illinois 60612, USA
| | | | | | | | | | | |
Collapse
|
135
|
Petheo GL, Girardin NC, Goossens N, Molnár GZ, Demaurex N. Role of nucleotides and phosphoinositides in the stability of electron and proton currents associated with the phagocytic NADPH oxidase. Biochem J 2006; 400:431-8. [PMID: 16842239 PMCID: PMC1698601 DOI: 10.1042/bj20060578] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2006] [Revised: 07/07/2006] [Accepted: 07/14/2006] [Indexed: 11/17/2022]
Abstract
The phagocytic NADPH oxidase (phox) moves electrons across cell membranes to kill microbes. The activity of this lethal enzyme is tightly regulated, but the mechanisms that control phox inactivation are poorly understood for lack of appropriate assays. The phox generates measurable electron currents, I(e), that are associated with inward proton currents, I(H). To study the inactivation of the phox and of its associated proton channel, we determined which soluble factors can stabilize I(e) (induced by the addition of NADPH) and I(H) (initiated by small depolarizing voltage steps) in inside-out patches from PMA-activated human eosinophils. I(e) decayed rapidly in the absence of nucleotides (tau approximately 6 min) and was maximally stabilized by the combined addition of 5 mM ATP and 50 microM of the non-hydrolysable GTP analogue GTP[S] (guanosine 5'-[gamma-thio]triphosphate) (tau approximately 57 min), but not by either ATP or GTP[S] alone. I(H) also decayed rapidly and was stabilized by the ATP/GTP[S] mixture, but maximal stabilization of I(H) required further addition of 25 muM PI(3,4)P2 (phosphoinositide 3,4-bisphosphate) to the cytosolic side of the patch. PI(3,4)P2 had no effect on I(e) and its stabilizing effect on I(H) could not be mimicked by other phosphoinositides. Reducing the ATP concentration below millimolar levels decreased I(H) stability, an effect that was not prevented by phosphatase inhibitors but by the non-hydrolysable ATP analogue ATP[S] (adenosine 5'-[gamma-thio]triphosphate). Our data indicate that the assembled phox complex is very stable in eosinophil membranes if both ATP and GTP[S] are present, but inactivates within minutes if one of the nucleotides is removed. Stabilization of the phox-associated proton channel in a highly voltage-sensitive conformation does not appear to involve phosphorylation but ATP binding, and requires not only ATP and GTP[S] but also PI(3,4)P2, a protein known to anchor the cytosolic phox subunit p47(phox) to the plasma membrane.
Collapse
Key Words
- cytochrome
- eosinophil
- nadph oxidase
- patch-clamp
- proton channel
- phosphoinositide
- atp[s], adenosine 5′-[γ-thio]triphosphate
- cgd, chronic granulomatous disease
- dpi, diphenyleneiodonium
- gap, gtpase-activating protein
- gtp[s], guanosine 5′-[γ-thio]triphosphate
- hv1/vsop, voltage-gated hydrogen channel 1/voltage sensor domain-only protein
- pi(3,4)p2, phosphoinositide 3,4-bisphosphate
- pip, phosphoinositide phosphate
- px domain, phox homology domain
Collapse
Affiliation(s)
- Gábor L Petheo
- Department of Cell Physiology and Metabolism, University of Geneva Medical School, 1 Michel-Servet, CH-1211 Geneva 4, Switzerland.
| | | | | | | | | |
Collapse
|
136
|
Utomo A, Cullere X, Glogauer M, Swat W, Mayadas TN. Vav proteins in neutrophils are required for FcgammaR-mediated signaling to Rac GTPases and nicotinamide adenine dinucleotide phosphate oxidase component p40(phox). THE JOURNAL OF IMMUNOLOGY 2006; 177:6388-97. [PMID: 17056570 DOI: 10.4049/jimmunol.177.9.6388] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Phagocytes generate reactive oxygen species, the regulation of which is important in eliminating ingested microbes while limiting tissue damage. Clustering of FcgammaRs results in the activation of Vav proteins, Rho/Rac guanine nucleotide exchange factors, and results in robust superoxide generation through the NADPH oxidase. In this study, studies in neutrophils isolated from mice deficient in Vav or Rac isoforms demonstrate a critical role for Vav3 in Rac2-dependent activation of the NADPH oxidase following FcgammaR clustering. However, studies in cytokine-primed cells revealed a strict requirement for Vav1 and Vav3 and Rac1 and Rac2 in the FcgammaR-mediated oxidative burst. In comparison, Vav was not essential for PMA or G protein-coupled receptor-mediated superoxide generation. The FcgammaR-mediated oxidative burst defect in Vav-deficient cells was linked to aberrant Rac activation as well as Rac- and actin-polymerization-independent, but PI3K-dependent, phosphorylation of the NADPH oxidase component p40(phox). In macrophages, Vav regulation of Rac GTPases was required specifically in FcgammaR-mediated activation of the oxidative burst, but not in phagocytosis. Thus, Vav proteins specifically couple FcgammaR signaling to NADPH oxidase function through a Rac-dependent as well as an unexpected Rac-independent signal that is proximal to NADPH oxidase activation and does not require actin polymerization.
Collapse
Affiliation(s)
- Ahmad Utomo
- Center of Excellence in Vascular Biology, Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
| | | | | | | | | |
Collapse
|
137
|
Lodge R, Diallo TO, Descoteaux A. Leishmania donovani lipophosphoglycan blocks NADPH oxidase assembly at the phagosome membrane. Cell Microbiol 2006; 8:1922-31. [PMID: 16848789 DOI: 10.1111/j.1462-5822.2006.00758.x] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Phagocytosis of Leishmania donovani promastigotes is characterized by an inhibition of phagolysosome biogenesis mediated by the surface glycolipid lipophosphoglycan (LPG). However, the consequences of this inhibition on macrophage function remain to be determined. In this study, we investigated the impact of LPG-mediated phagosome remodelling on the assembly and function of the NADPH oxidase complex. Phagocytosis of both wild-type and LPG-defective L. donovani promastigotes triggered the release of similar levels of superoxide. However, wild-type promastigotes, but not LPG-defective mutants, inhibited generation of superoxide at the phagosome. Confocal microscopy imaging revealed that the membrane component gp91(phox) and the Rho-family GTPase Rac1 were present on phagosomes containing either wild-type or LPG-defective promastigotes. In contrast, the NADPH oxidase cytosolic components p47(phox) and p67(phox) were excluded from phagosomes in a LPG-dependent fashion. This inhibition is not the consequence of a general defect in the initiation of the NADPH oxidase activation process because both wild-type and LPG-defective promastigotes induced p47(phox) phosphorylation and the formation of complexes containing p47(phox) and p67(phox). Thus, by remodelling their intracellular habitat, L. donovani promastigotes prevent the assembly of a functional phagosomal NADPH oxidase complex, thereby evading an important host innate defence mechanism.
Collapse
Affiliation(s)
- Robert Lodge
- INRS-Institut Armand Frappier and Centre for Host Parasite Interactions, Laval, QC, Canada, H7V 1B7
| | | | | |
Collapse
|
138
|
Lodge R, Descoteaux A. Phagocytosis of Leishmania donovani amastigotes is Rac1 dependent and occurs in the absence of NADPH oxidase activation. Eur J Immunol 2006; 36:2735-44. [PMID: 16955522 DOI: 10.1002/eji.200636089] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Macrophages produce little superoxide during phagocytosis of Leishmania donovani amastigotes. In this study, we characterized molecular events associated with L. donovani amastigotes uptake by mouse macrophages, to further define the mechanisms by which they are internalized without triggering superoxide production. Using transient transfections, we first showed that internalization of L. donovani amastigotes is mediated by the GTPases Rac1 and Arf6, of which Rac1 is recruited and retained on parasite-containing phagosomes. Next, we showed that, whereas internalization of amastigotes induced no superoxide release, co-internalization of serum-opsonized zymozan and amastigotes resulted in superoxide production. Furthermore, in co-internalization experiments, we detected superoxide production in over 95% of phagosomes containing IgG-opsonized SRBC compared to 5% of amastigote-harboring phagosomes. These results suggest that amastigotes evade the ability of macrophages to produce superoxide during phagocytosis. Consistently, we observed that amastigotes induced barely detectable phosphorylation of the NADPH oxidase component p47phox, leading to a defective phagosomal recruitment of p67phox and p47phox. Finally, we showed that amastigotes disrupt phagosomal lipid raft integrity, potentially interfering with NADPH oxidase assembly. Collectively, our results indicate that internalization of L. donovani amastigotes is a Rac1- and Arf6-dependent process that occurs in the absence of significant NADPH oxidase activation.
Collapse
Affiliation(s)
- Robert Lodge
- INRS-Institut Armand Frappier and Centre for host-parasite interactions, Laval, QC, Canada
| | | |
Collapse
|
139
|
Wilkinson BL, Landreth GE. The microglial NADPH oxidase complex as a source of oxidative stress in Alzheimer's disease. J Neuroinflammation 2006; 3:30. [PMID: 17094809 PMCID: PMC1637099 DOI: 10.1186/1742-2094-3-30] [Citation(s) in RCA: 168] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2006] [Accepted: 11/09/2006] [Indexed: 01/16/2023] Open
Abstract
Alzheimer's disease is the most common cause of dementia in the elderly, and manifests as progressive cognitive decline and profound neuronal loss. The principal neuropathological hallmarks of Alzheimer's disease are the senile plaques and the neurofibrillary tangles. The senile plaques are surrounded by activated microglia, which are largely responsible for the proinflammatory environment within the diseased brain. Microglia are the resident innate immune cells in the brain. In response to contact with fibrillar beta-amyloid, microglia secrete a diverse array of proinflammatory molecules. Evidence suggests that oxidative stress emanating from activated microglia contribute to the neuronal loss characteristic of this disease. The source of fibrillar beta-amyloid induced reactive oxygen species is primarily the microglial nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. The NADPH oxidase is a multicomponent enzyme complex that, upon activation, produces the highly reactive free radical superoxide. The cascade of intracellular signaling events leading to NADPH oxidase assembly and the subsequent release of superoxide in fibrillar beta-amyloid stimulated microglia has recently been elucidated. The induction of reactive oxygen species, as well as nitric oxide, from activated microglia can enhance the production of more potent free radicals such as peroxynitrite. The formation of peroxynitrite causes protein oxidation, lipid peroxidation and DNA damage, which ultimately lead to neuronal cell death. The elimination of beta-amyloid-induced oxidative damage through the inhibition of the NADPH oxidase represents an attractive therapeutic target for the treatment of Alzheimer's disease.
Collapse
Affiliation(s)
- Brandy L Wilkinson
- Alzheimer Laboratory, Department of Neuroscience, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Gary E Landreth
- Alzheimer Laboratory, Department of Neuroscience, Case Western Reserve University, Cleveland, OH 44106, USA
| |
Collapse
|
140
|
Shang F, Zhao L, Zheng Q, Wang J, Xu Z, Liang W, Liu H, Liu S, Zhang L. Simvastatin inhibits lipopolysaccharide-induced tumor necrosis factor-alpha expression in neonatal rat cardiomyocytes: The role of reactive oxygen species. Biochem Biophys Res Commun 2006; 351:947-52. [PMID: 17094942 DOI: 10.1016/j.bbrc.2006.10.134] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2006] [Accepted: 10/25/2006] [Indexed: 10/24/2022]
Abstract
Tumor necrosis factor-alpha (TNF-alpha) is implicated in heart failure and cardiomyocytes themselves can express TNF-alpha. Nevertheless, the mechanisms and regulations of TNF-alpha expression in cardiomyocytes remain poorly understood. The present study was to investigate the effects of simvastatin on TNF-alpha expression in cardiomyocytes and the underlying molecular mechanisms. In neonatal rat cardiomyocytes, RT-PCR and ELISA showed lipopolysaccharide (LPS)-induced TNF-alpha expression was attenuated by simvastatin pretreatment in a dose-dependent manner. The reactive oxygen species (ROS) scavenger N-acetylcysteine and the NADPH oxidase inhibitor diphenyleneiodonium also inhibited the LPS-induced expression of TNF-alpha. Dichlorofluorescein-fluorescence and cytochrome c reduction assay indicated LPS increased ROS generation and NADPH oxidase activity in cardiomyocytes, which were abrogated by simvastatin. Furthermore, similar to LPS, exogenous hydrogen peroxide also increased TNF-alpha secretion, but simvastatin did not significantly affect the hydrogen peroxide-induced TNF-alpha secretion. All the effects of simvastatin as mentioned above were completely reversed by concomitant pretreatment with mevalonate, a key intermediate during cholesterol synthesis. These results suggest that simvastatin attenuates LPS-induced TNF-alpha expression in cardiomyocytes via inhibition of activation of NADPH oxidase and subsequent ROS generation.
Collapse
Affiliation(s)
- Fujun Shang
- Department of Cardiology, Tangdu Hospital, Fourth Military Medical University, Xi'an 710038, PR China
| | | | | | | | | | | | | | | | | |
Collapse
|
141
|
Kim HS, Ye SK, Cho IH, Jung JE, Kim DH, Choi S, Kim YS, Park CG, Kim TY, Lee JW, Chung MH. 8-hydroxydeoxyguanosine suppresses NO production and COX-2 activity via Rac1/STATs signaling in LPS-induced brain microglia. Free Radic Biol Med 2006; 41:1392-403. [PMID: 17023266 DOI: 10.1016/j.freeradbiomed.2006.07.018] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2006] [Revised: 07/12/2006] [Accepted: 07/24/2006] [Indexed: 12/22/2022]
Abstract
Free 8-hydroxydeoxyguanosine (oh(8)dG), a nucleoside of 8-hydroxyguanine (oh(8)Gua), present in cytosol is not incorporated into DNA. However, nothing is known about its biological function when it presents in cytosol as a free form. We demonstrate here for the first time that oh(8)dG inhibits lipopolysaccharide (LPS)-induced nitric oxide (NO) production and cyclooxygenase-2 (COX-2) activity, and both gene transcriptions in microglia. Furthermore, oh(8)dG reduced mRNA levels of pro-inflammatory cytokine, such as IL-1beta, IL-6, and TNF-alpha, in activated BV2 cells. We also found that oh(8)dG suppressed reactive oxygen species (ROS) production through reduction of NADPH oxidase activity and blocked Rac1/STATs signal cascade. Finally, oh(8)dG suppressed recruitment of STATs and p300 to the iNOS and COX-2 promoters, and inhibited H3 histone acetylation. Taken together, these results provide new aspects of oh(8)dG as an anti-inflammatory agent.
Collapse
Affiliation(s)
- Hong Sook Kim
- Department of Pharmacology, Seoul National University College of Medicine, Chungno-gu, Seoul 110-799, Korea
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
142
|
Fricke I, Gabrilovich DI. Dendritic cells and tumor microenvironment: a dangerous liaison. Immunol Invest 2006; 35:459-83. [PMID: 16916762 PMCID: PMC1994724 DOI: 10.1080/08820130600803429] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The fact that the immune response to cancer is compromised has been convincingly demonstrated in murine tumor models as well as in cancer patients. The unresponsiveness of the host immune system is one of the major mechanisms of tumor escape as well as an important factor that limits the success of cancer immunotherapy. Inadequate function of professional antigen presenting cells dendritic cells (DC) in cancer is one of the major elements of compromised anti-tumor immune response. Despite substantial progress in recent years, the mechanism of inadequate DC function in cancer still remains unclear. The tumor microenvironment has emerged as an important component contributing to DC malfunction. In this review we will discuss the potential role of tumor microenvironment in DC dysfunction.
Collapse
Affiliation(s)
| | - Dmitry I. Gabrilovich
- Address for correspondence: Dmitry I. Gabrilovich, University of South Florida, 12902 Magnolia Dr. MRC 2067, Tampa, FL 33612, Ph. 813-903-6863, FAX 813-745-1328;
| |
Collapse
|
143
|
Yang HY, Kim J, Chung GH, Lee JC, Jang YS. Cross-linking of MHC class II molecules interferes with phorbol 12,13-dibutyrate-induced differentiation of resting B cells by inhibiting Rac-associated ROS-dependent ERK/p38 MAP kinase pathways leading to NF-kappaB activation. Mol Immunol 2006; 44:1577-86. [PMID: 17011624 DOI: 10.1016/j.molimm.2006.08.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2006] [Accepted: 08/11/2006] [Indexed: 10/24/2022]
Abstract
In addition to their essential role in antigen presentation, major histocompatibility complex (MHC) class II molecules have been described as the receptor associated with signal transduction regulating B-cell function. In previous experiments, we found that cross-linking of MHC class II molecules with corresponding anti-MHC class II antibodies inhibited NF-kappaB-activated signaling pathways associated with the proliferation and differentiation of the LPS-stimulated primary and resting B-cell line, 38B9. We also found that exposure to the anti-MHC class II antibody reduced the production of ROS, which function as secondary signal transducers, in the phorbol 12,13-dibutyrate (PDBU)-treated (but not in the LPS-treated) resting B-cell line. In this study, we investigated the molecular mechanisms in the ROS-associated signaling pathway leading to PDBU-induced NF-kappaB activation that results in B-cell differentiation and speculated that the signaling pathway was inhibited by exposure to the anti-MHC class II antibody. We also found that this inhibition was mediated through down-regulation of the activated Rac/ROS-associated ERK/p38 MAPK signaling pathway in PDBU-treated 38B9 cells. Collectively, these findings suggest that ROS-associated molecules are involved in MHC class II-associated negative signal transduction in resting B cells.
Collapse
Affiliation(s)
- Hee-Young Yang
- Division of Biological Sciences and the Institute for Molecular Biology and Genetics, Chonbuk National University, Chonju 561-756, Republic of Korea
| | | | | | | | | |
Collapse
|
144
|
Kosztáczky B, Fóris G, Seres I, Balogh Z, Fülöp P, Koncsos P, Paragh G. Neuropeptides induced a pronounced and statin-sensitive dysregulation of mevalonate cycle in human monocytes of patients with hypercholesterolemia. Neuropeptides 2006; 40:309-16. [PMID: 17049599 DOI: 10.1016/j.npep.2006.08.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2006] [Revised: 07/18/2006] [Accepted: 08/18/2006] [Indexed: 11/24/2022]
Abstract
Angiotensin II (Ang II) and leptin generate statin-inhibitable superoxide anion production that accounts for only part of the entire superoxide anion production. In our recent studies, we aimed at elucidating whether Ang II and leptin, affecting the intensity of the mevalonate cycle, are able to increase endogenous cholesterol synthesis. Furthermore, we compared the superoxide anion and cholesterol production capability of monocytes of healthy control volunteers and monocytes obtained from patients with hypercholesterolemia (HC). We also studied the differences of the produced statin-inhibitable superoxide anion and cholesterol synthesis in control and HC-monocytes, depending on the applied stimulating ligands. In control and HC-monocytes--stimulated by Ang II, leptin, fenyl-Me-Leu-Phe (FMLP), phorbol-12-myristate-13-acetate (PMA) and A23187--we determined the proportion of mevalonate cycle-dependent and -independent superoxide and cholesterol production, using lovastatin (Lov), and 25-hydroxycholesterol (25-HC). According to our results; (1) superoxide anion generation in HC-monocytes was elevated after Ang II, leptin and FMLP-stimulation, whereas PMA and A23187-stimulation had lower stimulating effect in HC than in control cells. (2) Cholesterol synthesis was increased only after stimulation with Ang II and leptin. (3) The Ang II and leptin-induced total superoxide anion generation and cholesterol synthesis were more elevated in HC than in control monocytes. (4) In contrast, the increase in Lov and 25-HC sensitive cholesterol synthesis were higher in resting, but lower in stimulated HC monocytes than in control cells. Summarizing our results, we concluded that Ang II and leptin are involved in enhancement of endogenous cholesterol synthesis through a statin-sensitive pathway.
Collapse
Affiliation(s)
- Béla Kosztáczky
- First Department of Medicine, Medical and Health Science Center, University of Debrecen, Nagyerdei krt. 98, Debrecen H-4012, Hungary
| | | | | | | | | | | | | |
Collapse
|
145
|
Abstract
Neutrophils are critical inflammatory cells that cause tissue damage in a range of diseases and disorders. Being bone marrow-derived white blood cells, they migrate from the bloodstream to sites of tissue inflammation in response to chemotactic signals and induce inflammation by undergoing receptor-mediated respiratory burst and degranulation. Degranulation from neutrophils has been implicated as a major causative factor in pulmonary disorders, including severe asphyxic episodes of asthma. However, the mechanisms that control neutrophil degranulation are not well understood. Recent observations indicate that granule release from neutrophils depends on activation of intracellular signalling pathways, including β-arrestins, the Rho guanosine triphosphatase Rac2, soluble NSF attachment protein (SNAP) receptors, the src family of tyrosine kinases, and the tyrosine phosphatase MEG2. Some of these observations suggest that degranulation from neutrophils is selective and depends on nonredundant signalling pathways. This review focuses on new findings from the literature on the mechanisms that control the release of granule-derived mediators from neutrophils.
Collapse
Affiliation(s)
- Paige Lacy
- Pulmonary Research Group, Department of Medicine, University of Alberta, Edmonton, AB.
| |
Collapse
|
146
|
Moe KT, Aulia S, Jiang F, Chua YL, Koh TH, Wong MC, Dusting GJ. Differential upregulation of Nox homologues of NADPH oxidase by tumor necrosis factor-alpha in human aortic smooth muscle and embryonic kidney cells. J Cell Mol Med 2006; 10:231-9. [PMID: 16563235 PMCID: PMC3933115 DOI: 10.1111/j.1582-4934.2006.tb00304.x] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
NADPH oxidases are important sources of vascular superoxide, which has been linked to the pathogenesis of atherosclerosis. Previously we demonstrated that the Nox4 subunit of NADPH oxidase is a critical catalytic component for superoxide production in quiescent vascular smooth muscle cells. In this study we sought to determine the role of Nox4 in superoxide production in human aortic smooth muscle cells (AoSMC) and embryonic kidney (HEK293) cells under proinflammatory conditions. Incubation with tumor necrosis factor-α (TNF-α, 10 ng/ml) for 12h increased superoxide production in both cell types, whereas angiotensin II, platelet-derived growth factor or interleukin-1β had little effects. Superoxide production was completely abolished by the NADPH oxidase inhibitors diphenyline iodonium and apocynin, but not by inhibitors of xanthine oxidase, nitric oxide synthase or mitochondrial electron transport. TNF-α upregulated the expression of Nox4 in AoSMC at both message and protein levels, while Nox1 and Nox2 were unchanged. In contrast, upregulation of Nox2 appeared to mediate the enhanced superoxide production by TNF-α in HEK293 cells. We suggest that Nox4 may be involved in increased superoxide generation in vascular smooth muscle cells under proinflammatory conditions.
Collapse
Affiliation(s)
- K T Moe
- Research and Development Unit, National Heart CentreSingapore
| | - S Aulia
- Research and Development Unit, National Heart CentreSingapore
| | - F Jiang
- Research and Development Unit, National Heart CentreSingapore
- Bernard O'Brien Institute of Microsurgery, St. Vincent's Hospital, The University of MelbourneVictoria, Australia
| | - Y L Chua
- Cardiothoracic Surgery Department, National Heart CentreSingapore
| | - T H Koh
- Cardiology Department, National Heart CenterSingapore
| | - M C Wong
- National Neuroscience Institute, Singapore General Hospital CampusSingapore
| | - G J Dusting
- Howard Florey Institute, University of Melbourne, VictoriaAustralia
- Bernard O'Brien Institute of Microsurgery, St. Vincent's Hospital, The University of MelbourneVictoria, Australia
- * Correspondence to: Professor Gregory J. DUSTING Bernard O'Brien Institute of Microsurgery, the University of Melbourne, 42 Fitzroy Street, Fitzroy, Victoria 3065, Australia Tel.: +61-3-9288 4062; Fax:+61-3-9416 0926 E-mail:
| |
Collapse
|
147
|
van Manen HJ, van Bruggen R, Roos D, Otto C. Single-cell optical imaging of the phagocyte NADPH oxidase. Antioxid Redox Signal 2006; 8:1509-22. [PMID: 16987007 DOI: 10.1089/ars.2006.8.1509] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The phagocyte NADPH oxidase is a key component of the innate immune response against invading microorganisms, because the generation of superoxide (O(2)(-)) inside the phagocytic vacuole by this enzyme is responsible for microbial killing by mechanisms that are directly or indirectly dependent on reactive oxygen species (ROS) formation. Most of what is known about the membrane-embedded and cytosolic NADPH oxidase subunits and their intricate network of interactions on assembly and activation has been derived from biochemical and biophysical studies involving subcellular fractionation or reconstituted cell-free systems. Such investigations can be complemented by single-cell microscopy on phagocytes, which may reveal spatial and/or temporal details about NADPH oxidase assembly that cannot be obtained from fractionated-cell assays. In recent years, we have investigated the NADPH oxidase in neutrophils using two complementary optical imaging techniques: Raman microscopy, a vibrational spectroscopic technique that does not require protein labeling, and live-cell fluorescence microscopy, which sheds light on the dynamics of NADPH oxidase assembly in individual cells. Here, we briefly introduce these techniques, compare their characteristics, and show their potential for studying NADPH oxidase at the single-cell level. New microscopy data are presented to illustrate the versatility of Raman and fluorescence microscopy on intact neutrophils.
Collapse
Affiliation(s)
- Henk-Jan van Manen
- Biophysical Engineering Group, Faculty of Science & Technology, Institute for Biomedical Technology, BMTI, and MESA+ Institute for Nanotechnology, University of Twente, Enschede, The Netherlands.
| | | | | | | |
Collapse
|
148
|
Abstract
The phagocytic NADPH oxidase is recognized as a critical component of innate immunity, responsible for generation of microbicidal reactive oxygen species (ROS). This enzyme is one representative of the Nox family of oxidases (Nox1-Nox5, Duox1, and Duox2) that exhibit diverse expression patterns and appear to serve a variety of functions related to ROS generation. Mounting evidence now suggests that several of these novel oxidases also serve in host defense, particularly those showing high expression along epithelial surfaces exposed to the external environment. Within these sites, Nox enzymes tend to be located on apical cell surfaces and release ROS into extracellular environments, where they can be used by known antimicrobial peroxidases. Moreover, microbial factors were shown in several cases to cause higher ROS production, either by direct oxidase activation or by inducing higher oxidase expression. Several oxidases are also induced by immune cytokines, including interferon-gamma, interleukin (IL)-4, and IL-13. Although most of the evidence supporting host defense roles for mammalian nonphagocytic oxidases remains circumstantial, recent evidence indicates that Drosophila Duox plays a role in host resistance to infection. Finally, oxidative defense against invading pathogens appears to be an ancient protective mechanism, because related oxidases are known to participate in disease resistance in plants.
Collapse
Affiliation(s)
- Thomas L Leto
- Molecular Defenses Section, Laboratory of Host Defenses, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland 20852, USA.
| | | |
Collapse
|
149
|
Abstract
Phagocytic leukocytes generate reactive oxygen species important for the killing of invading microorganisms. The source of these oxidants is the NADPH oxidase, a tightly controlled multicomponent enzyme made up of a membrane-associated catalytic moiety and cytosolic regulatory components that must assemble to form the active oxidase. The phagocyte NADPH oxidase was the first mammalian system shown to be directly regulated by a Rac GTPase. We review here our understanding of NADPH oxidase regulation by Rac, as well as the regulation of Rac itself, in phagocytic leukocytes. Rather than viewing Rac as a "cog" in the NADPH oxidase machinery, we argue for a view of Rac GTPases as critical "molecular switches" regulating the formation of ROS by phagocytic leukocytes under physiologic and pathologic conditions.
Collapse
Affiliation(s)
- Gary M Bokoch
- Department of Immunology, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, California 92037, USA.
| | | |
Collapse
|
150
|
Abstract
The production of reactive oxygen species (ROS) accompanies many signaling events. Antioxidants and ROS scavenging enzymes in general have effects that indicate a critical role for ROS in downstream signaling, but a mechanistic understanding of the contribution of ROS as second messengers is incomplete. Here, the role of reactive oxygen species in cell signaling is discussed, emphasizing the ability of ROS to directly modify signaling proteins through thiol oxidation. Examples are provided of protein thiol modifications that control signal transduction effectors that include protein kinases, phosphatases, and transcription factors. Whereas the effects of cysteine oxidation on these proteins in experimental systems is clear, it has proven more difficult to demonstrate these modifications in response to physiologic stimuli. Improved detection methods for analysis of thiol modification will be essential to define these regulatory mechanisms. Bridging these two areas of research could reveal new regulatory mechanisms in signaling pathways, and identify new therapeutic targets.
Collapse
Affiliation(s)
- Janet V Cross
- Department of Pathology, University of Virginia, Charlottesville, 22908, USA
| | | |
Collapse
|