scholarly journals Helicobacter pylori-Induced Interleukin-12 p40 Expression

2009 ◽  
Vol 77 (4) ◽  
pp. 1337-1348 ◽  
Author(s):  
Eriko Takeshima ◽  
Koh Tomimori ◽  
Hiromitsu Teruya ◽  
Chie Ishikawa ◽  
Masachika Senba ◽  
...  
Keyword(s):  
T Cells ◽  
Helicobacter Pylori ◽  
Protein Kinase ◽  
Epithelial Cells ◽  
Mrna Expression ◽  
Mitogen Activated Protein Kinase ◽  
Interleukin 12 ◽  
Phosphatidylinositol 3 Kinase ◽  
Mitogen Activated Protein ◽  
H Pylori

ABSTRACT Interleukin-12 (IL-12) is a heterodimeric cytokine produced by antigen-presenting cells that promotes the development of T-helper lymphocyte 1 (Th1). Chronic gastritis induced by Helicobacter pylori is considered a Th1-mediated process. IL-12 levels in gastric biopsy samples of H. pylori-infected patients are higher than in those of uninfected individuals, but the cellular source of IL-12 remains elusive. IL-12 staining was detected in mucosal epithelial cells, lymphocytes, and macrophages in specimens of patients with H. pylori-positive gastritis. Therefore, we investigated IL-12 p40 mRNA induction by H. pylori in gastric epithelial cells and T cells. Although cag pathogenicity island (PAI)-positive H. pylori induced IL-12 p40 mRNA expression, an isogenic mutant of the cag PAI failed to induce it in both cell types. Supernatants from H. pylori cultures and H. pylori VacA induced IL-12 p40 mRNA expression in T cells but not in epithelial cells. The activation of the IL-12 p40 promoter by H. pylori was mediated through NF-κB. The transfection of IκB kinase and NF-κB-inducing kinase dominant-negative mutants inhibited H. pylori-induced IL-12 p40 activation. Inhibitors of NF-κB, phosphatidylinositol 3-kinase, p38 mitogen-activated protein kinase, and Hsp90 suppressed H. pylori- and VacA-induced IL-12 p40 mRNA expression. The results indicate that H. pylori induces IL-12 p40 expression by the activation of NF-κB, phosphatidylinositol 3-kinase, and p38 mitogen-activated protein kinase. Hsp90 is also a crucial regulator of H. pylori-induced IL-12 p40 expression. In addition to the cag PAI, VacA might be relevant in the induction of IL-12 expression and a Th1-polarized response only in T cells.

scholarly journals Roles of the Ras-MEK-Mitogen-Activated Protein Kinase and Phosphatidylinositol 3-Kinase-Akt-mTOR Pathways in Jaagsiekte Sheep Retrovirus-Induced Transformation of Rodent Fibroblast and Epithelial Cell Lines

2005 ◽  
Vol 79 (7) ◽  
pp. 4440-4450 ◽  
Author(s):  
Naoyoshi Maeda ◽  
Wuxia Fu ◽  
Aurora Ortin ◽  
Marcelo de las Heras ◽  
Hung Fan
Keyword(s):  
Protein Kinase ◽  
Epithelial Cells ◽  
P38 Mapk ◽  
Cell Lines ◽  
Mitogen Activated Protein Kinase ◽  
Phosphatidylinositol 3 Kinase ◽  
Jaagsiekte Sheep Retrovirus ◽  
3T3 Fibroblasts ◽  
Mitogen Activated Protein ◽  
Nih 3T3

ABSTRACT Jaagsiekte sheep retrovirus (JSRV) is the causative agent of ovine pulmonary adenocarcinoma (OPA), a transmissible lung cancer of sheep. The virus can induce tumors rapidly, and we previously found that the JSRV envelope protein (Env) functions as an oncogene, because it can transform mammalian and avian fibroblast cell lines. (N. Maeda, Proc. Natl. Acad. Sci. USA 98:4449-4454, 2001). The molecular mechanisms of JSRV Env transformation are of considerable interest. Several reports suggested that the phosphatidylinositol 3-kinase/Akt pathway is important for transformation of mammalian fibroblasts but not for chicken fibroblasts. In this study, we found that Akt/mTOR is involved in JSRV transformation of mouse NIH 3T3 fibroblasts, because treatment with the mTOR inhibitor rapamycin reduced transformation. We also found that H/N-Ras inhibitor FTI-277 and MEK1/2 inhibitors PD98059 and U0126 strongly inhibited JSRV transformation of NIH 3T3 fibroblasts, suggesting that the H/N-Ras-MEK-mitogen-activated protein kinase (MAPK) p44/42 pathway is necessary for the transformation. In RK3E epithelial cells, the MEK1/2 inhibitors also eliminated transformation, but FTI-277 only partially inhibited transformation. It was noteworthy that p38 MAPK inhibitors enhanced JSRV transformation in both fibroblasts and epithelial cells. Treatment of transformed cells with p38 inhibitors both increased levels of phospho-MEK1/2 and phospho-p44/42 and induced rapid enhancement of the transformed phenotype. Immunohistochemical staining of tumor tissues from naturally and experimentally induced OPA and naturally occurring enzootic nasal adenocarcinoma revealed strong activation of MAPK p44/42 in all cases examined. However, p38 activation was not generally observed. These results indicate that signaling through two pathways (in particular, H/N-Ras-MEK-MAPK and, to a lesser extent, Akt-mTOR) is important for JSRV-induced transformation and that p38 MAPK has a negative regulatory effect on transformation, perhaps via MEK1/2 and p44/42.

scholarly journals Helicobacter pylori Activates the Cyclin D1 Gene through Mitogen- Activated Protein Kinase Pathway in Gastric Cancer Cells

2001 ◽  
Vol 69 (6) ◽  
pp. 3965-3971 ◽  
Author(s):  
Yoshihiro Hirata ◽  
Shin Maeda ◽  
Yuzo Mitsuno ◽  
Masao Akanuma ◽  
Yutaka Yamaji ◽  
...  
Keyword(s):  
Gastric Cancer ◽  
Helicobacter Pylori ◽  
Protein Kinase ◽  
Cyclin D1 ◽  
Pathogenicity Island ◽  
Mitogen Activated Protein Kinase ◽  
Ags Cells ◽  
Mitogen Activated Protein ◽  
H Pylori ◽  
Kinase Pathway

ABSTRACT Helicobacter pylori induces cellular proliferation in host cells, but the mechanism remains unclear. Thus, we examined the effect of H. pylori on cyclin D1, an important regulator of the cell cycle, especially in relation to intracellular signaling pathways. In a Northern blot analysis, cyclin D1 transcription in gastric cancer (AGS) cells was enhanced by coculture with H. pylori strain TN2 in a time-dependent and multiplicity-of-infection-dependent manner. An isogenic mutant form ofvacA also increased cyclin D1 transcription, but mutant forms of cagE or the entire cag pathogenicity island did not enhance cyclin D1 transcription. These effects were confirmed with a luciferase assay of the cyclin D1 promoter (pD1luc). Cyclin D1 promoter activation by H. pylori was inhibited by MEK inhibitors (U0126 and PD98059), indicating that the mitogen-activated protein kinase pathway may be involved in intracellular signal transduction. In contrast, transfection of a reporter plasmid having any point mutations of the NF-κB binding sites in the promoter (pD1-κB1M, pD1-κB2M, or pD1-κB1/2M) or cotransfection of dominant negative IκBα did not affect cyclin D1 activation by H. pylori. In conclusion, H. pylori activates cyclin D1 through the mitogen-activated protein kinase pathway and not through NF-κB activation in AGS cells. This activation of cyclin D1 is partly dependent on the cagpathogenicity island but not on vacA.

scholarly journals Helicobacter pylori Lipopolysaccharides Upregulate Toll-Like Receptor 4 Expression and Proliferation of Gastric Epithelial Cells via the MEK1/2-ERK1/2 Mitogen-Activated Protein Kinase Pathway

2009 ◽  
Vol 78 (1) ◽  
pp. 468-476 ◽  
Author(s):  
Shin-ichi Yokota ◽  
Tamaki Okabayashi ◽  
Michael Rehli ◽  
Nobuhiro Fujii ◽  
Ken-ichi Amano
Keyword(s):  
Helicobacter Pylori ◽  
Epithelial Cells ◽  
Mitogen Activated Protein Kinase ◽  
Gastric Epithelial Cells ◽  
Antigenic Epitope ◽  
Toll Like Receptor ◽  
Toll Like Receptor 4 ◽  
E Coli ◽  
Mitogen Activated Protein ◽  
H Pylori

ABSTRACT Helicobacter pylori is recognized as an etiological agent of gastroduodenal diseases. H. pylori produces various toxic substances, including lipopolysaccharide (LPS). However, H. pylori LPS exhibits extremely weakly endotoxic activity compared to the typical LPS, such as that produced by Escherichia coli, which acts through Toll-like receptor 4 (TLR4) to induce inflammatory molecules. The gastric epithelial cell lines MKN28 and MKN45 express TLR4 at very low levels, so they show very weak interleukin-8 (IL-8) production in response to E. coli LPS, but pretreatment with H. pylori LPS markedly enhanced IL-8 production induced by E. coli LPS by upregulating TLR4 via TLR2 and the MEK1/2-ERK1/2 pathway. The transcription factor NF-Y was activated by this signal and promoted transcription of the tlr4 gene. These MEK1/2-ERK1/2 signal-mediated activities were more potently activated by LPS carrying a weakly antigenic epitope, which is frequently found in gastric cancers, than by LPS carrying a highly antigenic epitope, which is associated with chronic gastritis. H. pylori LPS also augmented the proliferation rate of gastric epithelial cells via the MEK1/2-ERK1/2 pathway. H. pylori LPS may be a pathogenic factor causing gastric tumors by enhancing cell proliferation and inflammation via the MEK1/2-ERK1/2 mitogen-activated protein kinase cascade in gastric epithelial cells.

TGF-β1 stimulates HO-1 via the p38 mitogen-activated protein kinase in A549 pulmonary epithelial cells

2002 ◽  
Vol 283 (5) ◽  
pp. L1094-L1102 ◽  
Author(s):  
Wen Ning ◽  
Ruiping Song ◽  
Chaojun Li ◽  
Edward Park ◽  
Amir Mohsenin ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Epithelial Cells ◽  
Mrna Expression ◽  
P38 Mapk ◽  
Mapk Pathway ◽  
A549 Cells ◽  
Mitogen Activated Protein Kinase ◽  
P38 Mapk Pathway ◽  
Mitogen Activated Protein ◽  
Sb 203580

In lung injury and progressive lung diseases, the multifunctional cytokine transforming growth factor-β1 (TGF-β1) modulates inflammatory responses and wound repair. Heme oxygenase-1 (HO-1) is a stress-inducible protein that has been demonstrated to confer cytoprotection against oxidative injury and provide a vital function in maintaining tissue homeostasis. Here we report that TGF-β1 is a potent inducer of HO-1 and examined the signaling pathway by which TGF-β1 regulates HO-1 expression in human lung epithelial cells (A549). TGF-β1(1–5 ng/ml) treatment resulted in a marked time-dependent induction of HO-1 mRNA in A549 cells, followed by corresponding increases in HO-1 protein and HO enzymatic activity. Actinomycin D and cycloheximide inhibited TGF-β1-responsive HO-1 mRNA expression, indicating a requirement for transcription and de novo protein synthesis. Furthermore, TGF-β1 rapidly activated the p38 mitogen-activated protein kinase (p38 MAPK) pathway in A549 cells. A chemical inhibitor of p38 MAPK (SB-203580) abolished TGF-β1-inducible HO-1 mRNA expression. Both SB-203580 and expression of a dominant-negative mutant of p38 MAPK inhibited TGF-β1-induced ho-1 gene activation, as assayed by luciferase activity of an ho-1enhancer/luciferase fusion construct (pMHO1luc-33+SX2). These studies demonstrate the critical intermediacy of the p38 MAPK pathway in the regulation of HO-1 expression by TGF-β1.

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