Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.12.2 (MEK)
 18,161 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Heat shock protein (HSP) 27 has long been known to be a component of the p38 mitogen-activated protein kinase (MAPK) signaling pathway. p38 MAPK has important functions in the inflammatory response, but the role of HSP27 in inflammation has remained unknown. We have used small interfering RNAs to suppress HSP27 expression in HeLa cells and fibroblasts and found that it is required for pro-inflammatory cell signaling and the expression of pro-inflammatory genes. HSP27 is needed for the activation by interleukin (IL)-1 of TAK1 and downstream signaling by p38 MAPK, JNK, and their activators (MKK-3, -4, -6, -7) and IKKbeta. IL-1-induced ERK activation appears to be independent of HSP27. HSP27 is required for both IL-1 and TNF-induced signaling pathways for which the most upstream common signaling protein is TAK1. HSP27 is also required for IL-1-induced expression of the pro-inflammatory mediators, cyclooxygenase-2, IL-6, and IL-8. HSP27 functions to drive cyclooxygenase-2 and IL-6 expression by augmenting the activation of the kinase downstream of p38 MAPK, MK2, resulting in stabilization of cyclooxygenase-2 and IL-6 mRNAs. The mechanism may not occur in cells of myeloid lineage because HSP27 protein was undetectable in human monocytes and murine macrophages.
 ...
PMID:Heat shock protein 27 functions in inflammatory gene expression and transforming growth factor-beta-activated kinase-1 (TAK1)-mediated signaling. 1720 47

Recent evidence indicates that cancer cells express chemokine (CK) receptors and that their signaling is crucial for tumor proliferation, migration, and angiogenesis. The profiles of expression of CXC CK receptors (CXCR1-5) and their main ligands (growth-related oncogene, GRO1-2-3/CXCL1-2-3; interleukin 8, IL-8/CXCL8; monokine-induced gamma-interferon MIG/CXCL9; gamma-interferon-inducible-protein-10, IP-10/CXCL10; stromal cell-derived factor-1, SDF1/CXCL12; B-cell activating CK-1, BCA-1/CXCL13) were analyzed by reverse transcription polymerase chain reaction (RT-PCR) in surgical samples of human meningiomas. All the five receptors displayed high percentages of positive cases: 92% CXCR1, 89% CXCR2, 83% CXCR3, 78% CXCR4, and 94% CXCR5. Conversely, their ligands showed a lower pattern of expression: 40% IL-8, 42% GRO1-3, 42% IP-10, 28% MIG, 53% SDF1, and 3% BCA-1. SDF1/CXCR4 interaction plays a pivotal role in cancer proliferation. Thus, the signaling mechanisms activated by the exclusive binding between SDF1 and CXCR4 was investigated in 12 primary cultures from meningioma tissues. CXCR4 was functionally coupled as demonstrated by the significant increase of DNA synthesis in meningioma cells in response to SDF1, measured by [3H]-thymidine uptake. In three primary cultures, the SDF1-dependent mitogenic activity was associated with a marked phosphorylation of extracellular signal-regulated kinase (ERK1/2) as evaluated by Western blots. PD98059 (a MEK inhibitor) significantly reduced ERK1/2 activation, thus linking the SDF1/CXCR4 pathway to meningioma cell proliferation via ERK1/2 signal transduction. We demonstrate, for the first time in human meningiomas, the simultaneous expression of CXCR1-5 and their CKs and the mitogenic activity of SDF1/CXCR4, suggesting a pivotal role of these receptor-ligand pairs in meningeal tumors.
 ...
PMID:CXC receptor and chemokine expression in human meningioma: SDF1/CXCR4 signaling activates ERK1/2 and stimulates meningioma cell proliferation. 1738 78

Androgens have been associated with the risk for epithelial ovarian cancer (OVCA). Both IL-6 and IL-8 are also likely involved in the progression of OVCA. In order to discover the underline molecular mechanism, we investigated the modulation of androgen and two cytokines in the growth of epithelial OVCA. In these studies, the effect of 5alpha-dihydrotestosterone (DHT) on the expression levels of IL-6 and IL-8 was investigated. The effect of IL-6 and IL-8 on cell growth and androgen receptor (AR) expression was also analyzed. Gene expression profile analysis revealed that SKOV-3 cells, which express AR, IL-6 and IL-8 receptors, are suitable model for this study. We found that IL-6 and IL-8 markedly promoted SKOV-3 cell proliferation. Furthermore, DHT enhanced IL-6 and IL-8 secretion. Flutamide (Flu), an AR antagonist, completely abolished DHT-stimulated cell growth and the expression of IL-6 and IL-8. IL-6- or IL-8-induced cell proliferation was completely blocked by their specific neutralizing antibodies, which partially inhibited DHT-induced cell growth. In the absence of androgen, both cytokines enhanced AR expression and AR promoter activation, which was completely blocked by Flu. However, Flu failed tor educe IL-6-/IL-8-induced cell growth. Pretreatment of SKOV-3 cells with p38 MAPK, MEK1/2, and ErbB2 MAPK inhibitors, respectively, blocked IL-6-mediated enhancement of AR transcription while Src inhibitor blocked IL-8 induced AR transcription. These results provide a novel mechanism that androgens, IL-6 and IL-8 may form a common amplifying signaling cascade to modulate OVCA growth. Androgen-induced OVCA proliferation is partially occurring via enhanced IL-6 and IL-8 expression, and IL-6/IL-8 could also promote OVCA growth by activation of AR gene promoter.
 ...
PMID:Reciprocal regulation of 5alpha-dihydrotestosterone, interleukin-6 and interleukin-8 during proliferation of epithelial ovarian carcinoma. 1761 41

Alveolar macrophages, which generate high levels of reactive oxygen species, especially O(2)(*-), are involved in the recruitment of neutrophils to sites of inflammation and injury in the lung, and the generation of chemotactic proteins triggers this cellular recruitment. In this study, we asked whether O(2)(*-) generation in alveolar macrophages had a role in the expression of chemokines. Specifically, we hypothesized that O(2)(*-) generation is necessary for chemokine expression in alveolar macrophages after TNF-alpha stimulation. We found that alveolar macrophages have high constitutive NADPH oxidase activity that was not increased by TNF-alpha, but TNF-alpha increased the activity of the mitochondrial respiratory chain. In addition, the mitochondrial respiratory chain increased O(2)(*-) generation if the NADPH oxidase was inhibited. O(2)(*-) generation was necessary for macrophage inflammatory protein-2 (MIP-2) gene expression, because inhibition of NADPH oxidase or the mitochondrial respiratory chain or overexpression of Cu,Zn-superoxide dismutase significantly inhibited expression of MIP-2. TNF-alpha activated the ERK MAP kinase, and ERK activity was essential for chemokine gene expression. In addition, overexpression of the MEK1-->ERK pathway significantly increased IL-8 expression, and a small interfering RNA to the NADPH oxidase inhibited ERK- and TNF-alpha-induced chemokine expression. Collectively, these results suggest that in alveolar macrophages, O(2)(*-) generation mediates chemokine expression after TNF-alpha stimulation in an ERK-dependent manner.
 ...
PMID:Constitutive NADPH oxidase and increased mitochondrial respiratory chain activity regulate chemokine gene expression. 1770 89

Human neutrophil peptides (HNP) kill microorganisms but also modulate immune responses through upregulation of the chemokine IL-8 by activation of the nucleotide P2Y(6) receptor. However, the intracellular signaling mechanisms remain yet to be determined. Human lung epithelial cells (A549) and monocytes (U937) were stimulated with HNP in the absence and presence of the specific kinase inhibitors for Src, extracellular signal-regulated kinase-1 and -2 (ERK1/2), p38 mitogen-activated protein kinase (MAPK), c-Jun-N-terminal kinases (JNK), and Akt. HNP induced a rapid phosphorylation of the kinases in both cell types associated with a dose-dependent, selective production of IL-8 among 10 cytokines assayed. The HNP-induced IL-8 production was blocked by the Src tyrosine kinase inhibitor PP2, MEK1/2 inhibitor U0126, and the phosphatidylinositol 3 kinase (PI3K) inhibitor LY294002, but not by the JNK inhibitor SP600125 in both cell types. Treatment with the p38 inhibitor SB203580 attenuated the HNP-induced IL-8 production only in monocytes. Blockade of Src kinase blunted HNP-induced phosphorylation of the ERK1/2 and Akt but not p38 in monocytes. In contrast, Src inhibition had no effect on phosphorylation of the other kinases in the lung epithelial cells. We conclude that the activation of ERK1/2 and PI3K/Akt pathways is required for HNP-induced IL-8 release which occurs in a Src-independent manner in lung epithelial cells, while is Src-dependent in monocytes.
 ...
PMID:Differential signaling mechanisms of HNP-induced IL-8 production in human lung epithelial cells and monocytes. 1778 63

Tumor necrosis factor alpha (TNFalpha) is a pro-inflammatory cytokine that controls the initiation and progression of inflammatory diseases such as rheumatoid arthritis. Tpl2 is a MAPKKK in the MAPK (i.e. ERK) pathway, and the Tpl2-MEK-ERK signaling pathway is activated by the pro-inflammatory mediators TNFalpha, interleukin (IL)-1beta, and bacterial endotoxin (lipopolysaccharide (LPS)). Moreover, Tpl2 is required for TNFalpha expression. Thus, pharmacologic inhibition of Tpl2 should be a valid approach to therapeutic intervention in the pathogenesis of rheumatoid arthritis and other inflammatory diseases in humans. We have developed a series of highly selective and potent Tpl2 inhibitors, and in the present study we have used these inhibitors to demonstrate that the catalytic activity of Tpl2 is required for the LPS-induced activation of MEK and ERK in primary human monocytes. These inhibitors selectively target Tpl2 in these cells, and they block LPS- and IL-1beta-induced TNFalpha production in both primary human monocytes and human blood. In rheumatoid arthritis fibroblast-like synoviocytes these inhibitors block ERK activation, cyclooxygenase-2 expression, and the production of IL-6, IL-8, and prostaglandin E(2), and the matrix metalloproteinases MMP-1 and MMP-3. Taken together, our results show that inhibition of Tpl2 in primary human cell types can decrease the production of TNFalpha and other pro-inflammatory mediators during inflammatory events, and they further support the notion that Tpl2 is an appropriate therapeutic target for rheumatoid arthritis and other human inflammatory diseases.
 ...
PMID:Pharmacologic inhibition of tpl2 blocks inflammatory responses in primary human monocytes, synoviocytes, and blood. 1784 81

The hepatitis C virus (HCV) non-structural (NS) 3/4A protein complex inhibits the retinoic acid inducible gene I (RIG-I) pathway by proteolytically cleaving mitochondria-associated CARD-containing adaptor protein Cardif, and this leads to reduced production of beta interferon (IFN-beta). This study examined the expression of CCL5 (regulated upon activation, normal T-cell expressed and secreted, or RANTES), CXCL8 (interleukin 8) and CXCL10 (IFN-gamma-activated protein 10, or IP-10) chemokine genes in osteosarcoma cell lines that inducibly expressed NS3/4A, NS4B, core-E1-E2-p7 and the entire HCV polyprotein. Sendai virus (SeV)-induced production of IFN-beta, CCL5, CXCL8 and CXCL10 was downregulated by the NS3/4A protein complex and by the full-length HCV polyprotein. Expression of NS3/4A and the HCV polyprotein reduced the binding of interferon regulatory factors (IRFs) 1 and 3 and, to a lesser extent, nuclear factor (NF)-kappaB (p65/p50) to their respective binding elements on the CXCL10 promoter during SeV infection. Furthermore, binding of IRF1 and IRF3 to the interferon-stimulated response element-like element, and of c-Jun and phosphorylated c-Jun to the activator protein 1 element of the CXCL8 promoter, was reduced when NS3/4A and the HCV polyprotein were expressed. In cell lines expressing NS3/4A and the HCV polyprotein, the subcellular localization of mitochondria was changed, and this was kinetically associated with the partial degradation of endogenous Cardif. These results indicate that NS3/4A alone or as part of the HCV polyprotein disturbs the expression of IRF1- and IRF3-regulated genes, as well as affecting mitogen-activated protein kinase kinase- and NF-kappaB-regulated genes.
 ...
PMID:Hepatitis C virus proteins interfere with the activation of chemokine gene promoters and downregulate chemokine gene expression. 1819 74

Tumor necrosis factor (TNF)-alpha is central to the endometriotic disease process. TNF-alpha receptor signaling regulates epithelial cell secretion of inflammation and invasion mediators. Because epithelial cells are a disease-inducing component of the endometriotic lesion, we explored the response of 12Z immortalized human epithelial endometriotic cells to TNF-alpha. This report reveals the impact of disruption of established TNF-alpha-induced signaling cascades on the expression of biomarkers of inflammation and epithelial-mesenchymal transition (EMT) from endometriotic epithelial cells. Note that we show the molecular potential of soluble TNF-R1 [TNF binding protein (TBP)] and a panel of small molecule kinase inhibitors to block endometriotic gene expression directly. The TNF-alpha receptor is demonstrated to signal through IkappaB kinase complex (IKK) 2 > IkappaB > nuclear factor kappaB, extracellular signal-regulated kinase > mitogen-activated protein kinase kinase (MEK), p38, and phosphatidylinositol 3-kinase (PI3K) > Akt1/2. TNF-alpha induces the expression of transcripts for inflammatory mediators interleukin (IL)-6, IL-8, regulated on activation normal T cell expressed and secreted, TNF-alpha, granulocyte macrophage-colony-stimulating factor (GM-CSF), and monocyte chemoattractant protein (MCP)-1 and also invasion mediators matrix metalloproteinase (MMP)-7, MMP-9, and intracellular adhesion molecule-1. Indeed, TBP inhibits the TNF-alpha-induced expression of all the above endometriotic genes in 12Z endometriotic epithelial cells. The secretion of IL-6, IL-8, GMCSF, and MCP-1 by TNF-alpha is blocked by TBP. Interestingly, MEK, p38, and IKK inhibitors block TNF-alpha-induced IL-8, IL-6, and GM-CSF secretion and 12z invasion, whereas the PI3K inhibitors do not. The only inhibitor to block MCP-1 expression is the p38 inhibitor. Last, TBP, MEK inhibitor, or p38 inhibitor also block cell surface expression of N-cadherin, a marker of mesenchymal cells. Taken together, these results demonstrate that interruption of TNF-alpha-induced signaling pathways in human endometriotic epithelial cells results in decreased expression and secretion of biomarkers for inflammation, EMT, and disease progression.
 ...
PMID:Tumor necrosis factor-alpha regulates inflammatory and mesenchymal responses via mitogen-activated protein kinase kinase, p38, and nuclear factor kappaB in human endometriotic epithelial cells. 1825 6

A member of a new subfamily of G protein-coupled receptors, protease-activated receptor 2 (PAR2), is highly expressed on endothelial cells and plays an important role in inflammation. The purpose of this study was to determine the molecular mechanism used by PAR2 to induce IL-8 production and thereby mediate cell adhesion. We observed that PAR2-activating peptide (PAR2-AP) significantly increase peripheral blood mononuclear cells adhere to endothelial cells. Both PAR2-AP and the endogenous PAR2 activator trypsin caused concentration- and time-dependent increase in endothelial IL-8 production, and this effect was concentration dependently and selectively attenuated by the p38 mitogen-activated protein kinase (MAPK) inhibitor SB203580. Western blotting analysis showed that PAR2-AP induced phosphorylation of p38 MAPK and its upstream protein kinase MAPK kinase 3/6 (MKK3/6) in a time-dependent manner. Using reverse-transcriptase-polymerase chain reaction and enzyme-linked immunosorbent assay, PAR2-AP was found to cause an increase in IL-8 mRNA expression and its transcription factor activating transcription factor 2, respectively,. As expected, these signals were suppressed by SB203580 in a concentration-dependent manner. Furthermore, introduction of dominant-negative vectors targeting p38 MAPK, MKK3, and MKK6 abolished PAR2-AP-mediated IL-8 production and cell adhesion function. In conclusion, PAR2 via p38 MAPK signaling regulates IL-8 production and thereby mediates cell adhesion.
 ...
PMID:The p38 mitogen-activated protein kinase pathway plays a critical role in PAR2-induced endothelial IL-8 production and leukocyte adhesion. 1827 46

The proinflammatory cytokine interleukin (IL)-1 activates several hundred genes within the same cell. This occurs in part by activation of the MKK7-JNK-c-Jun signaling pathway whose precise role in the regulation of individual inflammatory genes is still incompletely understood. To identify the genes that are under specific control of activated JNK, we used a JNK-MKK7 fusion protein. Genome-wide microarray analysis revealed EGR-1 as the transcript that was most strongly induced by JNK-MKK7. IL-1-stimulated EGR-1 mRNA and protein expression were impaired in cells lacking JNK or c-Jun. Transcriptional activation of the EGR-1 promoter by JNK-MKK7 or by IL-1 required a single upstream AP-1 site and three distal serum-response elements (SRE). Reconstitution experiments in c-Jun-deficient cells revealed that c-Jun is required for EGR-1 transcription through both the AP-1 site and the distal SREs. By chromatin immunoprecipitation analysis, we found IL-1-inducible recruitment of c-Jun to the AP-1 site and to the region containing the three distal SREs. These experiments suggest that c-Jun plays a dual role in EGR-1 transcription. It directly binds to the AP-1 element, and at the same time it is essential for promoter activation through the three distal SREs by an indirect unknown mechanism. As predicted by TRANSFAC analysis and verified by ChIP experiments, IL-1-induced EGR-1 protein binds to the promoter regions of inflammatory mediators such as IL-6, IL-8, and CCL2. Furthermore, short interfering RNA-mediated suppression of EGR-1 partially suppresses IL-1-inducible transcription of IL-8, IL-6, and CCL2. In summary, we provide novel evidence for a complex c-Jun-mediated mechanism that is essential for inducible EGR-1 expression. We identify this pathway as a previously unrecognized part of a multistep gene regulatory network that controls cytokine and chemokine expression via the IL-1-MKK7-JNK-c-Jun-EGR-1 pathway.
 ...
PMID:Transcriptional regulation of EGR-1 by the interleukin-1-JNK-MKK7-c-Jun pathway. 1828 87


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>