Induction of group IVC phospholipase A2 in allergic asthma: transcriptional regulation by TNFα in bronchoepithelial cells

2012 ◽  
Vol 442 (1) ◽  
pp. 127-137 ◽  
Author(s):  
Justin S. Bickford ◽  
Kimberly J. Newsom ◽  
John-David Herlihy ◽  
Christian Mueller ◽  
Benjamin Keeler ◽  
...  
Keyword(s):  
Gene Expression ◽  
Phospholipase A2 ◽  
Rna Polymerase Ii ◽  
Allergic Asthma ◽  
Nuclear Factor Κb ◽  
Dominant Negative ◽  
Lung Epithelial Cells ◽  
Bioactive Lipids ◽  
Eicosanoid Release ◽  
Factor Α

Airway inflammation in allergen-induced asthma is associated with eicosanoid release. These bioactive lipids exhibit anti- and pro-inflammatory activities with relevance to pulmonary pathophysiology. We hypothesized that sensitization/challenge using an extract from the ubiquitous fungus Aspergillus fumigatus in a mouse model of allergic asthma would result in altered phospholipase gene expression, thus modulating the downstream eicosanoid pathway. We observed the most significant induction in the group IVC PLA2 (phospholipase A2) [also known as cPLA2γ (cytosolic PLA2γ) or PLA2G4C]. Our results infer that A. fumigatus extract can induce cPLA2γ levels directly in eosinophils, whereas induction in lung epithelial cells is most likely to be a consequence of TNFα (tumour necrosis factor α) secretion by A. fumigatus-activated macrophages. The mechanism of TNFα-dependent induction of cPLA2γ gene expression was elucidated through a combination of promoter deletions, ChIP (chromatin immunoprecipitation) and overexpression studies in human bronchoepithelial cells, leading to the identification of functionally relevant CRE (cAMP-response element), NF-κB (nuclear factor κB) and E-box promoter elements. ChIP analysis demonstrated that RNA polymerase II, ATF-2 (activating transcription factor 2)–c-Jun, p65–p65 and USF (upstream stimulating factor) 1–USF2 complexes are recruited to the cPLA2γ enhancer/promoter in response to TNFα, with overexpression and dominant-negative studies implying a strong level of co-operation and interplay between these factors. Overall, our results link cytokine-mediated alterations in cPLA2γ gene expression with allergic asthma and outline a complex regulatory mechanism.

scholarly journals Activation of Nuclear Factor κb and bcl-x Survival Gene Expression by Nerve Growth Factor Requires Tyrosine Phosphorylation of IκBα

2001 ◽  
Vol 152 (4) ◽  
pp. 753-764 ◽  
Author(s):  
Nguyen Truc Bui ◽  
Antonia Livolsi ◽  
Jean-Francois Peyron ◽  
Jochen H.M. Prehn
Keyword(s):  
Gene Expression ◽  
Tyrosine Phosphorylation ◽  
Fluorescent Protein ◽  
Nuclear Translocation ◽  
Nuclear Factor Κb ◽  
Dominant Negative ◽  
Dominant Negative Mutant ◽  
Nuclear Factor ◽  
Human Neuroblastoma ◽  
Tnf Α

NGF has been shown to support neuron survival by activating the transcription factor nuclear factor-κB (NFκB). We investigated the effect of NGF on the expression of Bcl-xL, an anti–apoptotic Bcl-2 family protein. Treatment of rat pheochromocytoma PC12 cells, human neuroblastoma SH-SY5Y cells, or primary rat hippocampal neurons with NGF (0.1–10 ng/ml) increased the expression of bcl-xL mRNA and protein. Reporter gene analysis revealed a significant increase in NFκB activity after treatment with NGF that was associated with increased nuclear translocation of the active NFκB p65 subunit. NGF-induced NFκB activity and Bcl-xL expression were inhibited in cells overexpressing the NFκB inhibitor, IκBα. Unlike tumor necrosis factor-α (TNF-α), however, NGF-induced NFκB activation occurred without significant degradation of IκBs determined by Western blot analysis and time-lapse imaging of neurons expressing green fluorescent protein–tagged IκBα. Moreover, in contrast to TNF-α, NGF failed to phosphorylate IκBα at serine residue 32, but instead caused significant tyrosine phosphorylation. Overexpression of a Y42F mutant of IκBα potently suppressed NFG-, but not TNF-α–induced NFκB activation. Conversely, overexpression of a dominant negative mutant of TNF receptor-associated factor-6 blocked TNF-α–, but not NGF-induced NFκB activation. We conclude that NGF and TNF-α induce different signaling pathways in neurons to activate NFκB and bcl-x gene expression.

Increased cytochrome P-450 2E1 expression sensitizes hepatocytes to c-Jun-mediated cell death from TNF-α

2002 ◽  
Vol 282 (2) ◽  
pp. G257-G266 ◽  
Author(s):  
Hailing Liu ◽  
Brett E. Jones ◽  
Cynthia Bradham ◽  
Mark J. Czaja
Keyword(s):  
Cell Death ◽  
Oxidant Stress ◽  
Nuclear Factor Κb ◽  
Dominant Negative ◽  
Tnf Α ◽  
Cyp2e1 Expression ◽  
Factor Α ◽  
Jnk Activation ◽  
Cytochrome P 450 ◽  
Necrosis Factor

The mechanisms underlying hepatocyte sensitization to tumor necrosis factor-α (TNF-α)-mediated cell death remain unclear. Increases in hepatocellular oxidant stress such as those that occur with hepatic overexpression of cytochrome P-450 2E1 (CYP2E1) may promote TNF-α death. TNF-α treatment of hepatocyte cell lines with differential CYP2E1 expression demonstrated that overexpression of CYP2E1 converted the hepatocyte TNF-α response from proliferation to apoptotic and necrotic cell death. Death occurred despite the presence of increased levels of nuclear factor-κB transcriptional activity and was associated with increased lipid peroxidation and GSH depletion. CYP2E1-overexpressing hepatocytes had increased basal and TNF-α-induced levels of c-Jun NH2-terminal kinase (JNK) activity, as well as prolonged JNK activation after TNF-α stimulation. Sensitization to TNF-α-induced cell death by CYP2E1 overexpression was inhibited by antioxidants or adenoviral expression of a dominant-negative c-Jun. Increased CYP2E1 expression sensitized hepatocytes to TNF-α toxicity mediated by c-Jun and overwhelming oxidative stress. The chronic increase in intracellular oxidant stress created by CYP2E1 overexpression may serve as a mechanism by which hepatocytes are sensitized to TNF-α toxicity in liver disease.

scholarly journals Small-molecule inhibitor of OGG1 suppresses proinflammatory gene expression and inflammation

Science ◽  
2018 ◽  
Vol 362 (6416) ◽  
pp. 834-839 ◽  
Author(s):  
Torkild Visnes ◽  
Armando Cázares-Körner ◽  
Wenjing Hao ◽  
Olov Wallner ◽  
Geoffrey Masuyer ◽  
...  
Keyword(s):  
Gene Expression ◽  
Immune Cell ◽  
Nuclear Factor Κb ◽  
Cell Recruitment ◽  
Inflammatory Conditions ◽  
Molecule Inhibitor ◽  
Proinflammatory Gene ◽  
Factor Α ◽  
Proinflammatory Gene Expression

The onset of inflammation is associated with reactive oxygen species and oxidative damage to macromolecules like 7,8-dihydro-8-oxoguanine (8-oxoG) in DNA. Because 8-oxoguanine DNA glycosylase 1 (OGG1) binds 8-oxoG and because Ogg1-deficient mice are resistant to acute and systemic inflammation, we hypothesized that OGG1 inhibition may represent a strategy for the prevention and treatment of inflammation. We developed TH5487, a selective active-site inhibitor of OGG1, which hampers OGG1 binding to and repair of 8-oxoG and which is well tolerated by mice. TH5487 prevents tumor necrosis factor–α–induced OGG1-DNA interactions at guanine-rich promoters of proinflammatory genes. This, in turn, decreases DNA occupancy of nuclear factor κB and proinflammatory gene expression, resulting in decreased immune cell recruitment to mouse lungs. Thus, we present a proof of concept that targeting oxidative DNA repair can alleviate inflammatory conditions in vivo.

Streptococcus pneumoniae induced p38 MAPK- and NF-κB-dependent COX-2 expression in human lung epithelium

2006 ◽  
Vol 290 (6) ◽  
pp. L1131-L1138 ◽  
Author(s):  
Philippe Dje N’Guessan ◽  
Stefan Hippenstiel ◽  
Mirabelle O. Etouem ◽  
Janine Zahlten ◽  
Wiebke Beermann ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Epithelial Cells ◽  
Rna Polymerase Ii ◽  
P38 Mapk ◽  
Pneumococcal Pneumonia ◽  
Community Acquired Pneumonia ◽  
Dominant Negative ◽  
Alveolar Epithelial Cells ◽  
Lung Epithelial Cells ◽  
Cox 2

Streptococcus pneumoniae is a major cause of community-acquired pneumonia and death from infectious diseases in industrialized countries. Lung airway and alveolar epithelial cells comprise an important barrier against airborne pathogens. Cyclooxygenase (COX)-derived prostaglandins, such as PGE2, are considered to be important regulators of lung function. Herein, we tested the hypothesis that pneumococci induced COX-2-dependent PGE2 production in pulmonary epithelial cells. Pneumococci-infected human pulmonary epithelial BEAS-2B cells released PGE2. Expression of COX-2 but not COX-1 was dose and time dependently increased in S. pneumoniae-infected BEAS-2B cells as well as in lungs of mice with pneumococcal pneumonia. S. pneumoniae induced degradation of IκBα and DNA binding of NF-κB. A specific peptide inhibitor of the IκBα kinase complex blocked pneumococci-induced PGE2 release and COX-2 expression. In addition, we noted activation of p38 MAPK and JNK in pneumococci-infected BEAS-2B cells. PGE2 release and COX-2 expression were reduced by p38 MAPK inhibitor SB-202190 but not by JNK inhibitor SP-600125. We analyzed interaction of kinase pathways and NF-κB activation: dominant-negative mutants of p38 MAPK isoforms α, β2, γ, and δ blocked S. pneumoniae-induced NF-κB activation. In addition, recruitment of NF-κB subunit p65/RelA and RNA polymerase II to the cox2 promoter depended on p38 MAPK but not on JNK activity. In summary, p38 MAPK- and NF-κB-controlled COX-2 expression and subsequent PGE2 release by lung epithelial cells may contribute significantly to the host response in pneumococcal pneumonia.

Role of the MyD88 transduction signaling pathway in endothelial activation by antiphospholipid antibodies

Blood ◽  
2003 ◽  
Vol 101 (9) ◽  
pp. 3495-3500 ◽  
Author(s):  
Elena Raschi ◽  
Cinzia Testoni ◽  
Daniela Bosisio ◽  
Maria O. Borghi ◽  
Takao Koike ◽  
...  
Keyword(s):  
Antiphospholipid Antibodies ◽  
Fetal Loss ◽  
Endothelial Activation ◽  
Nuclear Factor Κb ◽  
Dominant Negative ◽  
Signaling Cascade ◽  
Glycoprotein I ◽  
Tnf Α ◽  
Factor Α

Antiphospholipid syndrome (APS) is an autoimmune disease characterized by the persistent presence of antiphospholipid antibodies (aPLs) and recurrent thrombosis or fetal loss. The thrombophilic state has been partially related to the induction of a proinflammatory and procoagulant endothelial cell (EC) phenotype induced by anti–β2-glycoprotein I (β2-GPI) antibodies that bind β2-GPI expressed on the EC surface. Anti–β2-GPI antibody binding has been shown to induce nuclear factor-κB (NF-κB) translocation leading to a proinflammatory EC phenotype similar to that elicited by interaction with microbial products (lipopolysaccharide [LPS]) and proinflammatory cytokines (interleukin 1β [IL-1β], tumor necrosis factor α [TNF-α]). However, the upstream signaling events are not characterized yet. To investigate the endothelial signaling cascade activated by anti–β2-GPI antibodies, we transiently cotransfected immortalized human microvascular endothelial cells (HMEC-1) with dominant-negative constructs of different components of the pathway (ΔTRAF2, ΔTRAF6, ΔMyD88) together with reporter genes (NF-κB luciferase and pCMV-β-galactosidase). Results showed that both human anti–β2-GPI IgM monoclonal antibodies as well as polyclonal affinity-purified anti–β2-GPI IgG display a signaling cascade comparable to that activated by LPS or IL-1. ΔTRAF6 and ΔMyD88 significantly abrogate antibody-induced as well as IL-1– or LPS-induced NF-κB activation, whereas ΔTRAF2 (involved in NF-κB activation by TNF) does not affect it. Moreover, anti– β2-GPI antibodies and LPS followed the same time kinetic of IL-1 receptor–activated kinase (IRAK) phosphorylation, suggesting an involvement of the toll-like receptor (TLR) family. Our findings demonstrate that anti–β2-GPI antibodies react with their antigen likely associated to a member of the TLR/IL-1 receptor family on the EC surface and directly induce activation.

scholarly journals Lung Krüppel-like factor (LKLF) is a transcriptional activator of the cytosolic phospholipase A2 α promoter

2005 ◽  
Vol 387 (1) ◽  
pp. 239-246 ◽  
Author(s):  
Marilee J. WICK ◽  
Stacy BLAINE ◽  
Vicki VAN PUTTEN ◽  
Milene SAAVEDRA ◽  
Raphael A. NEMENOFF
Keyword(s):  
Epithelial Cells ◽  
Phospholipase A2 ◽  
Promoter Activity ◽  
Cytosolic Phospholipase A2 ◽  
Dominant Negative ◽  
Lung Epithelial Cells ◽  
Mitogen Activated Protein Kinase ◽  
Normal Lung ◽  
Cytosolic Phospholipase ◽  
Lung Epithelial

Increased expression of cPLA2 (cytosolic phospholipase A2) has been shown to be the cause of tumorigenesis of NSCLC (non-small-cell lung cancer). Our laboratory has previously demonstrated that oncogenic forms of Ras increase transcription of cPLA2 in normal lung epithelial cells and NSCLC lines through activation of the ERK (extracellular-signal-regulated kinase) and JNK (c-Jun N-terminal kinase) MAPK (mitogen-activated protein kinase) family. We have also defined a minimal region of the cPLA2 promoter that is critical for this induction. To identify potential transcription factors that bind to this region and regulate expression, a yeast one-hybrid screen was performed with a rat lung cDNA library. Multiple members of the Krüppel family were identified, with LKLF (lung Krüppel-like factor) being isolated a number of times. Overexpression of LKLF in lung epithelial cells or Drosophila SL-2 cells increased cPLA2 promoter activity. Conversely, expression of a dominant negative form of LKLF inhibited induction of cPLA2 promoter activity by oncogenic Ras in normal lung epithelial cells and NSCLC. By electrophoretic mobility-shift assay analysis, it was found that LKLF bound to a GC-rich region of the cPLA2 promoter located between −37 and −30 upstream from the transcription start site. Expression of siRNA (small interfering RNA) directed against LKLF inhibited basal expression of cPLA2 in lung epithelial cells and blocked induction by H-Ras. In NSCLC, siRNA against LKLF co-operated with siRNA against Sp1 (stimulatory protein 1) to inhibit cPLA2 promoter activity. Finally, recombinant LKLF was a substrate for ERKs. These results indicate that LKLF is an important regulator of cPLA2 expression and participates in the induction of this protein, which is critical for increased eicosanoid production associated with lung tumorigenesis.

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