Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.24 (mitogen-activated protein kinase)
 95,810 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mitogen-activated protein (MAP) kinase-mediated signal-transduction pathways convert extracellular stimulation into a variety of cellular functions. However, the roles of MAP kinases in neutrophils are not well understood yet. Protein phosphorylation analysis of cellular MAP kinases indicates that exposure of human neutrophils to chemotactic factor FMLP as well as granulocyte-macrophage CSF, PMA, or ionomycin rapidly induced the activation of p38 and p44/42 MAP kinases, but stimulation with inflammatory cytokine TNF-alpha triggered the activation of p38 MAP kinase only. To study the cellular functions of these MAP kinases, the inhibitor SB20358, which specifically inhibited enzymatic activity of cellular p38 MAP kinase, and the inhibitor PD98059, which specifically blocked the induced protein phosphorylation and activation of p44/42 MAP kinase in intact neutrophils, were utilized. Inhibition of the cellular p38 MAP kinase activation almost completely abolished the TNF-alpha-stimulated IL-8 production and superoxide generation of human neutrophils. In addition, the FMLP-induced neutrophil chemotaxis as well as superoxide generation were suppressed markedly by inhibiting the activation of cellular p38 MAP kinase, but not p44/42 MAP kinase. Moreover, RIA indicates that the activation of cellular p38 MAP kinase was required for the neutrophil IL-8 production stimulated by granulocyte-macrophage CSF or LPS as well as TNF-alpha, but not for that induced by PMA or ionomycin. These results demonstrate that the activation of cellular p38 MAP kinase is indispensable for the TNF-alpha- or FMLP-mediated cellular functions in human neutrophils, and suggest that p38 MAP kinase may play a different role in response to distinct stimulation.
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PMID:p38 mitogen-activated protein kinase activation is required for human neutrophil function triggered by TNF-alpha or FMLP stimulation. 946 62

Central to the pathogenesis of Salmonella typhimurium is its ability to engage the host cell in a two-way biochemical interaction. As a consequence of this interaction, a dedicated protein secretion system, termed type III, is activated in these bacteria and directs the translocation of signaling proteins into the host cell. Secretion of these proteins stimulates host cell signal transduction pathways that lead to a variety of cellular responses. An important feature of S. typhimurium pathogenesis is the induction of a profound inflammatory response in the intestinal epithelium. In this report, we show that S. typhimurium induces host cell signal transduction pathways that lead to the activation of the transcription factors NF-kappaB and AP-1, resulting in the production of proinflammatory cytokines such as IL-8. We also show that S. typhimurium infection of cultured intestinal epithelial cells results in the activation of the mitogen-activated protein (MAP) kinases ERK, JNK, and p38. Induction of these signaling pathways and the synthesis of IL-8 was strictly dependent on the function of the invasion-associated type III protein secretion system encoded by S. typhimurium. Pretreatment of cells with the highly specific p38 MAP kinase inhibitor SB 203580 prevented S. typhimurium-induced IL-8 production. These results indicate that the inflammatory response induced by S. typhimurium may be due to the specific stimulation of MAP kinase signaling pathways leading to nuclear responses.
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PMID:Involvement of mitogen-activated protein kinase pathways in the nuclear responses and cytokine production induced by Salmonella typhimurium in cultured intestinal epithelial cells. 954 96

The proinflammatory cytokines interleukin (IL)-1 and tumor necrosis factor (TNF) promote HIV type 1 viral replication in vitro. In the present studies, HIV production was increased in the macrophagic U1 cell line expressing the HIV genome after exposure to IL-1beta, osmotic stress, or surface adhesion, suggesting a confluence of signaling pathways for proinflammatory cytokines and cell stressors. The p38 mitogen-activated protein kinase (MAPK) mediates both cytokine and stress responses; thus the role of this kinase in HIV production was investigated. HIV production as measured by p24 antigen correlated with changes in the expression of a specific (non-alpha) isoform of p38 MAPK. In the presence of a specific p38 MAPK inhibitor (p38 inh), IL-1beta-induced HIV production was suppressed by more than 90% and IL-1beta-induced IL-8 production was suppressed completely, both with IC50 of 0.01 microM. p38 inhibition blocked cell-associated p24 antigen and secreted virus to a similar extent. The p38 inh also decreased constitutive HIV production in freshly infected peripheral blood mononuclear cells by up to 50% (P < 0.05). Interruption of p38 MAPK activity represents a viable target for inhibition of HIV.
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PMID:Role of p38 mitogen-activated protein kinase in HIV type 1 production in vitro. 963 65

C-reactive protein (CRP) is a unique serum pentraxin and the prototype acute phase reactant. CRP is a ligand for specific receptors on phagocytic leukocytes, and mediates activation reactions of monocytes/macrophages, but inhibits the respiratory burst of neutrophils (PMN). Since CRP selectively accumulates at inflammatory sites in which IL-8 is also produced, we tested the effects of CRP on the responsiveness of PMN to IL-8 and the bacterial chemotactic peptide, FMLP-phenylalanine (FMLPP). Purified human CRP inhibited the chemotactic response of PMN to IL-8 and FMLPP. A mouse IgM mAb that was generated against the leukocyte CRP receptor (CRP-R) also inhibited the chemotactic response. Incubation of purified CRP with activated PMN generated CRP-derived peptides that also inhibited chemotaxis. A synthetic CRP peptide (residues 27-38) that binds to the CRP-R had weak chemotactic activity, whereas two other CRP synthetic peptides (residues 174-185 and 191-205) inhibited chemotaxis of PMNs to both IL-8 and FMLPP. CRP did not alter receptor-specific binding of IL-8, but exerted its effect at the level of signaling. CRP augmented both IL-8- and FMLPP-induced mitogen-activated protein kinase (extracellular signal-regulated kinase-2) activity. CRP at acute phase levels increased both agonist-induced and noninduced phosphatidylinositol-3 kinase activity. The results suggest a role for CRP as a regulator of leukocyte infiltration at inflammatory sites.
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PMID:Effect of human C-reactive protein on chemokine and chemotactic factor-induced neutrophil chemotaxis and signaling. 972 53

The cytokine interleukin-1 (IL-1) is a major inflammatory hormone which activates a broad range of genes during inflammation. The signaling mechanisms triggered by IL-1 include activation of several distinct protein kinase systems. The stress-activated protein kinase (SAPK), also termed Jun N-terminal kinase (JNK), is activated particularly strongly by the cytokine. In an attempt to delineate its role in activation of gene expression by IL-1, we inhibited the IL-1-induced SAPK/JNK activity by stable overexpression of either a catalytically inactive mutant of SAPKbeta (SAPKbeta(K-R)) or antisense RNA to SAPKbeta in human epidermal carcinoma cells. A detailed analysis of signal transduction in those cells showed that activation of neither NFkappaB nor p38 mitogen-activated protein kinase was affected, suggesting that we achieved specific blockade of the SAPK/JNK. In untransfected and vector-transfected KB cells, IL-1 induced a strong increase in expression of IL-6 and IL-8 mRNA, along with the synthesis of high amounts of the proteins. In two KB cell clones stably overexpressing the mutant SAPKbeta(K-R), and three clones stably overexpressing antisense RNA to SAPKbeta, expression of IL-6 and IL-8 in response to IL-1 was strongly reduced at both the mRNA and protein level. These data indicate that the SAPK/JNK pathway provides an indispensable signal for IL-1-induced expression of IL-6 and IL-8.
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PMID:Stress-activated protein kinase/Jun N-terminal kinase is required for interleukin (IL)-1-induced IL-6 and IL-8 gene expression in the human epidermal carcinoma cell line KB. 972 73

Increased numbers of activated eosinophils in bronchial tissue is a feature of asthma and may, in part, be attributed to the prolonged cytokine-dependent survival of eosinophils within the inflamed microenvironment. Low-dose oral theophylline was previously shown to reduce the number of activated eosinophils within the sub-mucosa following allergen exposure. A number of inhibitory actions of theophylline have been described which relate to eosinophil recruitment and activation, including inhibition of cell migration and release of granule basic proteins. In this study we investigated the ability of theophylline to inhibit the release of preformed GM-CSF and IL-8 from eosinophils in vitro, as these cytokines may serve an autocrine function in eosinophil survival in vivo. Eosinophils rapidly released GM-CSF and IL-8 spontaneously, and release was further enhanced in response to sIgA-coated beads. Theophylline inhibited the stimulated, but not the spontaneous, release of both cytokines. We previously reported the role of protein kinase A in inhibition of arachidonic acid mobilization and LTC4 synthesis. Therefore we speculate that cAMP-dependent activation of protein kinase A following theophylline treatment of eosinophils resulted in inhibition of Raf-1 and MAPK/MAPKK dependent activation of phospholipase A2 and consequently inhibition of degranulation and cytokine release.
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PMID:Theophylline inhibits the release of eosinophil survival cytokines--is Raf-1 the protein kinase A target? 975 86

Paclitaxel (Taxol) is a novel anti-cancer drug that has shown efficacy toward several malignant tumors, particularly ovarian tumors. We reported previously that paclitaxel can induce interleukin (IL)-8 promoter activation in subgroups of ovarian cancer through the activation of both AP-1 and nuclear factor kappaB. Further analysis of paclitaxel analogs indicates that the degree of IL-8 induction by analysis correlates with the extent of cell death; however, IL-8 itself is not the cause of cell death. This suggests that pathways that lead to IL-8 and cell death may overlap, although IL-8 per se does not kill tumor cells. To decipher the upstream signals for paclitaxel-induced transcriptional activation and cell death, we studied the involvement of protein kinases that lead to the activation of AP-1, specifically the c-Jun NH2-terminal kinase (JNK1), p38, and the extracellular signal-regulated kinase 1 (ERK1). The role of IkappaB in paclitaxel-induced cell death was also analyzed. Paclitaxel activated JNK, and to a lesser degree p38, but not ERK1. Paclitaxel-induced IL-8 promoter activation was inhibited by dominant-inhibitory mutants of JNK, p38, and the super-repressor form of IkappaBalpha, but not by dominant-inhibitory forms of ERK1. Dominant-inhibitory mutants of JNK1 also greatly reduced paclitaxel-induced cell death, and the kinetics of JNK induction was closely followed by DNA fragmentation. These results indicate (i) that paclitaxel activates the JNK signaling pathway and (ii) that JNK activation is a common point of paclitaxel-induced gene induction and cell death.
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PMID:Paclitaxel (Taxol)-induced gene expression and cell death are both mediated by the activation of c-Jun NH2-terminal kinase (JNK/SAPK). 977 47

We investigated whether intercellular adhesion molecule-1 (ICAM-1) transduces outside-in signals for the production of chemokines IL-8 and RANTES in endothelial cells. Cross-linking of ICAM-1 induced IL-8 and RANTES mRNA expressions and increased their protein synthesis and secretions in endothelial cells. Furthermore, ICAM-1 cross-linking activated 44- and 42-kDa mitogen-activated protein (MAP) kinases (ERK1 and ERK2) in endothelial cells, as indicated by the electrophoretic mobility shift of MAP kinases on SDS-polyacrylamide gels. Finally, the specific MEK inhibitor PD98059 inhibited ICAM-1-induced IL-8 and RANTES production in endothelial cells. Taken together, these results indicate that stimulation of ICAM-1 induces IL-8 and RANTES production through the activation of 44- and 42-kDa MAP kinases in endothelial cells, suggesting that ICAM-1-induced chemokine production in endothelial cells would further attract and activate leukocytes to induce intense inflammation.
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PMID:Cross-linking of intercellular adhesion molecule-1 induces interleukin-8 and RANTES production through the activation of MAP kinases in human vascular endothelial cells. 978 8

Activation of the extracellular signal-regulated kinase (ERK) pathway has been shown to occur in monocytes following stimulation with LPS. However, the importance of this event for monocyte function is not clear. To address this issue, we used the novel MAP/ERK kinase (MEK) inhibitor, U0126. Stimulation of monocytes with LPS resulted in activation of the mitogen-activated protein kinase (MAPK) family members ERK, Jun NH2-terminal kinase (JNK), and p38. Treatment of monocytes with LPS in the presence of U0126 blocked the activation of ERK1 and ERK2. However, the activation of Jun NH2-terminal kinase and p38 family members was not affected by the compound, confirming the selectivity of U0126. To examine the effects of MEK inhibition on monocyte function, we measured production of the cytokines IL-1, IL-8, and TNF, as well as PGE2. Monocytes treated with LPS in the presence of U0126 failed to release IL-1, IL-8, TNF, or PGE2. The failure to secrete IL-1 and TNF was due to decreased levels of mRNA. These results demonstrate that activation of MEK/ERK is critical for cytokine and PGE2 production by monocytes in response to LPS.
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PMID:Inhibition of MAP kinase kinase prevents cytokine and prostaglandin E2 production in lipopolysaccharide-stimulated monocytes. 982 May 49

Interleukin-8 (IL-8) is a chemokine that belongs to the alpha-chemokine or CXC subfamily and is produced by a wide variety of human cells, including monocytes and polymorphonuclear cells (PMN). IL-8 is secreted in response to inflammatory stimuli, notably bacterial products such as lipopolysaccharide (LPS), but little is known about the mechanisms by which these agents mediate IL-8 induction. In this report, we show that Mycoplasma fermentans lipid-associated membrane proteins (LAMPf) induce the production of high levels of IL-8 by THP-1 (human monocyte) cells and PMN at the same extent as LPS. It was previously demonstrated that stimulation of monocytic cells with either LPS or LAMPf led to a series of common downstream signaling events, including the activation of protein tyrosine kinase and of mitogen-activated protein kinase cascades. By using PD-98059 and SB203580, two potent and selective inhibitors of MEK1 (a kinase upstream of ERK1/2) and p38, respectively, we have demonstrated that both ERK1/2 and p38 cascades play a key role in the production of IL-8 by monocytes and PMN stimulated with bacterial fractions.
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PMID:Involvement of mitogen-activated protein kinase pathways in interleukin-8 production by human monocytes and polymorphonuclear cells stimulated with lipopolysaccharide or Mycoplasma fermentans membrane lipoproteins. 991 78


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