Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.12.2 (MEK)
18,161 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Stimulation of the APC by Porphyromonas gingivalis LPS has been shown to result in the production of certain pro- and anti-inflammatory cytokines. However, the signaling pathways that regulate these processes are currently unknown. In the present study, the role of the phosphatidylinositol 3 kinase (PI3K)-Akt pathway in regulating P. gingivalis LPS-induced production of IL-10, IL-12 p40, and IL-12 p70 by human monocytes was investigated. P. gingivalis LPS selectively activates the PI3K-Akt pathway via Toll-like receptor 2, and inhibition of this pathway results in an abrogation of extracellular signal-regulated kinase 1/2 phosphorylation, whereas the activation of p38 and c-Jun N-terminal kinase 1/2 kinases were unaffected. Analysis of cytokine production following stimulation of monocytes with P. gingivalis LPS revealed that inhibition of the PI3K pathway differentially regulated IL-10 and IL-12 synthesis. IL-10 production was suppressed, whereas IL-12 levels were enhanced. Inhibition of P. gingivalis LPS-mediated activation of the PI3K-Akt pathway resulted in a pronounced augmentation of NF-kappaB p65 that was independent of IkappaB-alpha degradation. Furthermore, the ability of the PI3K-Akt pathway to modulate IL-10 and IL-12 production appears to be mediated by the selective suppression of extracellular signal-regulated kinase 1/2 activity, as the MEK1 inhibitor PD98059 closely mimicked the effects of wortmannin and LY294002 to differentially regulate IL-10 and IL-12 production by P. gingivalis LPS-stimulated monocytes. These studies provide new insight into how engagement of the PI3K-Akt pathway by P. gingivalis LPS affects the induction of key immunoregulatory cytokines that control both qualitative and quantitative aspects of innate and adaptive immunity.
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PMID:Role of the phosphatidylinositol 3 kinase-Akt pathway in the regulation of IL-10 and IL-12 by Porphyromonas gingivalis lipopolysaccharide. 1284 38

As an immunosuppressive and anti-inflammatory cytokine, IL-10 was recently reported to play roles in CCR5 expression in human monocytes. CCR5 promoter regions contain Oct-2, TCF-1alpha, GATA, and STAT binding sites. Here, we studied the signals involved in the CCR5 expression in IL-10-stimulated cells using the HL-60 cell line. HL-60 cells were stimulated with PMA and differentiated to macrophage-like cells, then stimulated with IL-10. IL-10 induced significant expression of CCR5 protein and CCR5 mRNA in these cells. The induction of CCR5 by IL-10 was inhibited by a MEK-1 inhibitor, PD98059. In addition, IL-10 induced tyrosine (Tyr) phosphorylation of Erk, as well as serine (Ser) and Tyr phosphorylation of STAT-3. Tyr phosphorylation of Erk and Ser phosphorylation of STAT-3 were inhibited by PD98059, while Tyr phosphorylation of STAT-3 was not inhibited by PD98059. DNA binding activity of STAT-3 was observed by the stimulation with IL-10, which was inhibited by PD98059. These results first indicate that Erk1/2 and STAT-3 regulate CCR5 expression, and that Erk-mediated phosphorylation of Ser is required for full stimulation of STAT-3 in CCR5 expression.
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PMID:Interleukin-10-induced CCR5 expression in macrophage like HL-60 cells: involvement of Erk1/2 and STAT-3. 1291 53

Lipopolysaccharide (LPS) and porins of Gram-negative outer membranes are the main pathogenic factors implicated in the clinical syndrome of septic shock. The biological activity of porins and LPS are similar, but they occur by different mechanisms. It seems that porins act through different intracellular pathways with respect to LPS. In this study we analyzed the role of several inhibitors of the MEK/ERK signal pathway on the induction of proinflammatory and immunological cytokines in U937 cell line stimulated by Salmonella typhimurium porins and compared it to the cytokine induction after LPS stimulation. We investigated the effects of p38 MAP kinase inhibitor SB-203580, MEK/ERK kinase inhibitor PD-098059 and Raf-1 inhibitor forskolin, and demonstrated that they modulate cytokine mRNA expression in a different manner as a consequence of the use of porins or LPS as stimuli. TNF-alpha and IL-1beta mRNA expression is decreased by PD-098059 after stimulation with LPS but not with porins in differentiated U937 cells. IL-10 mRNA expression is inhibited by SB-203580 and PD-098059 after stimulation with porins in U937 cells. IL-6 and IL-8 mRNA expression is not changed by PD-098059 or SB-203580, after stimulation either with porins or LPS. Furthermore, mRNA expression of the studied cytokines, except for GM-CSF, is not changed using forskolin.
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PMID:Induction of cytokine mRNA expression in U937 cells by Salmonella typhimurium porins is regulated by different phosphorylation pathways. 1462 44

Neuromedin U (NmU), originally isolated from porcine spinal cord and later from other species, is a novel peptide that potently contracts smooth muscle. NmU interacts with two G protein-coupled receptors designated as NmU-1R and NmU-2R. This study demonstrates a potential proinflammatory role for NmU. In a mouse Th2 cell line (D10.G4.1), a single class of high affinity saturable binding sites for (125)I-labeled NmU (K(D) 364 pM and B(max) 1114 fmol/mg protein) was identified, and mRNA encoding NmU-1R, but not NmU-2R, was present. Competition binding analysis revealed equipotent, high affinity binding of NmU isopeptides to membranes prepared from D10.G4.1 cells. Exposure of these cells to NmU isopeptides resulted in an increase in intracellular Ca(2+) concentration (EC(50) 4.8 nM for human NmU). In addition, NmU also significantly increased the synthesis and release of cytokines including IL-4, IL-5, IL-6, IL-10, and IL-13. Studies using pharmacological inhibitors indicated that maximal NmU-evoked cytokine release required functional phospholipase C, calcineurin, MEK, and PI3K pathways. These data suggest a role for NmU in inflammation by stimulating cytokine production by T cells.
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PMID:Neuromedin U elicits cytokine release in murine Th2-type T cell clone D10.G4.1. 1558 45

Hepatic ischemia-reperfusion injury is an inevitable consequence during liver surgery. The outcome is particularly poor in cirrhotic livers, which are more prone to hepatic ischemia-reperfusion injury. We aim to study whether FTY720 could attenuate hepatic ischemia-reperfusion injury both in normal and in cirrhotic livers. We applied a 70% liver-ischemia (60 min) model in rats with normal or cirrhotic livers. FTY720 was given 20 min before ischemia and 10 min before reperfusion (1 mg/kg, i.v.). Liver tissues and blood were sampled at 20 min, 60 min, 90 min, 6 h and 24 h after reperfusion for detection of MAPK-Egr-1, Akt pathways and caspase cascade. Hepatic ultrastructure and apoptosis were also compared. FTY720 significantly improved liver function in the rats with normal and cirrhotic livers. Akt pathway was activated at 6 and 24 h after reperfusion. FTY720 significantly down-regulated Egr-1, ET-1, iNOS and MIP-2 accompanied with up-regulation of A20, IL-10, HO-1 and Hsp70. MAPK (Raf-MEK-Erk) pathway was down-regulated. Hepatic ultrastructure was well maintained and fewer apoptotic liver cells were found in the FTY720 groups. In conclusion, FTY720 attenuates ischemia-reperfusion injury in both normal and cirrhotic livers by activation of cell survival Akt signaling and down-regulation of Egr-1 via Raf-MEK-Erk pathway.
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PMID:FTY720 attenuates hepatic ischemia-reperfusion injury in normal and cirrhotic livers. 2824 Aug 25

Lipopolysaccharide (LPS) induces a marked delay in human neutrophil apoptosis that is reversed by the anti-inflammatory cytokine IL-10. The effect of IL-10 is specific since other agents that delay neutrophil apoptosis are not affected. To investigate mechanisms underlying the actions of IL-10, we examined signaling pathways activated by LPS per se and in response to IL-10. The MAPK kinase (MEK) 1 inhibitor PD098059, the protein kinase C (PKC) inhibitor Ro31,8220, and the phosphatidylinositol-3 kinase (PI3-K) inhibitor LY294002 all partially reversed LPS-mediated retardation of neutrophil apoptosis, but the p38 MAPK inhibitor SB203850 did not. LPS activates the transcription factor NF-kappaB, however, IL-10 did not affect the ability of LPS to activate NF-kappaB as assessed by IkappaB-alpha proteolysis. Although IL-10 did not alter activation of ERK by GM-CSF or TNF-alpha, it did inhibit activation induced by LPS. Thus our data illustrate that LPS-induced neutrophil survival is regulated by the MAPK, PKC and PI3-K pathways as well as NF-kappaB, and can be reversed by IL-10, through a mechanism involving inhibition of ERK activation. Because of the specific nature of this inhibition, we conclude that IL-10 interferes with an ERK activation pathway, which is not involved in GM-CSF or TNF-alpha signaling.
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PMID:Interleukin-10 inhibits lipopolysaccharide-induced survival and extracellular signal-regulated kinase activation in human neutrophils. 1610 68

The anti-inflammatory/immunoparalytic phase of the systemic inflammatory response syndrome (SIRS) following major insult (surgery, thermal/traumatic injury) is of major clinical importance in the neonate, during which the risk of infection is particularly great. Here, the mechanisms by which TNF-alpha production is suppressed in response to infection are largely unknown. We questioned whether TNF-alpha itself could be a critical mediator of this suppression. Monocytes, isolated from cord blood (n=3), were treated with LPS (100 ng/ml), TNF-alpha (10 ng/ml, +/- anti-TNF-alpha antibody) for 18 and 36 h. Cells were then restimulated with LPS (Gram -ve) or Pam-3-Cys (Gram +ve) for 24 h. This was also done in the presence of selective inhibitors of MAP kinases p38, MEK and JNK. TNF-alpha, IL-6, IL-10 and IL-8 were quantified by ELISA CD86 and HLA-DR expression were determined flow cytometrically. Cells stimulated with LPS for 24 h produced TNF-alpha (282 pg/ml), IL-10 (1,236 pg/ml), IL-6 (2,694 pg/ml) and IL-8 (2,144 pg/ml). In cells pre-exposed to TNF-alpha for 36 h, there was a significant suppression in TNF-alpha and IL-6 levels (9 and 221 pg/ml, respectively) (P<0.05) with minimal impact on IL-10 (1,206 pg/ml) and IL-8 levels (1,886 pg/ml). A similar effect was seen with Pam-3-Cys with a tenfold decrease in levels of TNF-alpha and IL-6 (86-->8.5 pg/ml and 458-->46 pg/ml, respectively) with no effect on IL-10 and IL-8 levels. Anti-TNF-alpha antibody negated this effect. Inhibition of p38 kinase reversed the TNF-alpha effect. Inhibition of the JNK and MEK kinases had no effect. A reduction in the expression of CD86 and HLA-DR was observed. This ex-vivo model of non-septic SIRS demonstrates that TNF-alpha, released during a major insult, can suppress subsequent monocyte responses to bacterial agents through p38 MAP kinase, making it a potential therapeutic target.
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PMID:TNF-alpha is a mediator of the anti-inflammatory response in a human neonatal model of the non-septic shock syndrome. 1629 53

Engaging mammalian Toll-like receptors (TLRs) activate both the NF-kappaB and mitogen-activated protein kinase signaling pathways. Here we establish that mitogen-activated protein 3 kinase Tpl2, levels of which are markedly reduced in nfkb1(-/-) cells, is required for extracellular signal-regulated kinase (ERK) activation in bone marrow-derived macrophages and B cells stimulated with diverse TLR ligands. Despite rescuing TLR-dependent ERK activation in nfkb1(-/-) bone marrow-derived macrophages by using an estrogen receptor-regulated version of the mitogen-activated protein 3 kinase, c-Raf (Raf:ER), CpG or LPS induction of IL-10 was only partially restored in nfkb1(-/-) cells expressing Raf:ER, a finding consistent with NF-kappaB1 regulating IL-10 by a combination of ERK-independent and -dependent mechanisms. Collectively, our findings indicate that the Tpl2/MEK/ERK signaling module is a master regulator of ERK-dependent gene expression downstream of TLRs in different hemopoietic cells.
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PMID:Diverse Toll-like receptors utilize Tpl2 to activate extracellular signal-regulated kinase (ERK) in hemopoietic cells. 1648 70

The expression of intercellular adhesion molecule-1 (ICAM-1) and vascular adhesion molecule-1 (VCAM-1) on human gingival fibroblasts (HGF) may be important for migration and retention of inflammatory cells in periodontally diseased tissue. This study aimed to assess which cytokines regulate ICAM-1 and VCAM-1 expression on HGF. Tumour necrosis factor (TNF)-alpha and interferon (IFN)-gamma enhanced both ICAM-1 and VCAM-1 expression on HGF. Interleukin (IL)-1beta mainly up-regulated ICAM-1 expression. On the other hand, IL-4 and IL-13 enhanced only VCAM-1 expression on HGF. IL-10 did not modulate both ICAM-1 and VCAM-1 expression. Transforming growth factor (TGF)-beta1 enhanced ICAM-1 expression. However, TGF-beta1 inhibited the VCAM-1 expression induced by TNF-alpha or IL-4. Both ICAM-1 and VCAM-1 expression by HGF was inhibited by nuclear factor-kappaB (NF-kappaB) activation inhibitor (MG-132). Mitogen-activated protein kinases (MAPK) inhibitors did not influence ICAM-1 expression induced by TNF-alpha. Interestingly, VCAM-1 expression was enhanced by MEK inhibitor (PD98059) and c-Jun NH2-terminal kinase (JNK) inhibitor (SP600125). These results mean that the balance of cytokines in periodontally diseased tissue may be essential for control of ICAM-1 and VCAM-1 expression on HGF, and the balance of ICAM-1 and VCAM-1 expression might be important for regulation of leucocytes infiltration and retention in periodontally diseased tissue.
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PMID:Cytokines differentially regulate ICAM-1 and VCAM-1 expression on human gingival fibroblasts. 1673 19

Adenylate cyclase toxin (CyaA) of Bordetella pertussis binds to CD11b/CD18 on macrophages and dendritic cells (DC) and confers virulence to the bacteria by subverting innate immune responses of the host. We have previously demonstrated that CyaA promotes the induction of IL-10-secreting regulatory T cells in vivo by modulating DC activation. Here, we examine the mechanism of immune subversion, specifically, the modulation of TLR signaling pathways in DC. We found that CyaA synergized with LPS to induce IL-10 mRNA and protein expression in DC but significantly inhibited IL-12p70 production. CyaA enhanced LPS-induced phosphorylation of p38 MAPK and ERK in DC, and inhibitors of p38 MAPK, MEK, or NF-kappaB suppressed IL-10 production in response to LPS and CyaA. However, inhibition of p38 MAPK, MEK, and NF-kappaB did not reverse the inhibitory effect of CyaA on TLR agonist-induced IL-12 production. Furthermore, CyaA suppression of IL-12 was independent of IL-10. In contrast, CyaA suppressed LPS- and IFN-gamma-induced IFN-regulatory factor-1 (IRF-1) and IRF-8 expression in DC. The modulatory effects of CyaA were dependent on adenylate cyclase activity and induction of intracellular cAMP, as an enzyme-inactive mutant of CyaA failed to modulate TLR-induced signaling in DC, whereas the effects of the wild-type toxin were mimicked by stimulation of the DC with PGE2. Our findings demonstrate that CyaA modulates TLR agonist-induced IL-10 and IL-12p70 production in DC by, respectively, enhancing MAPK phosphorylation and inhibiting IRF-1 and IRF-8 expression and that this is mediated by elevation of intercellular cAMP concentrations.
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PMID:Adenylate cycalse toxin of Bordetella pertussis inhibits TLR-induced IRF-1 and IRF-8 activation and IL-12 production and enhances IL-10 through MAPK activation in dendritic cells. 1840 Oct 6


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