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)

6-(Methylsulfinyl)hexyl isothiocyanate (6-MITC) is an active ingredient of Wasabi (Wasabia japonica (Miq.) Matsumura), which is a very popular pungent spice in Japan. To clarify the cellular signaling mechanism underlying the anti-inflammatory action of 6-MITC, we investigated the effects of 6-MITC on the expression of inducible nitric oxide synthase (iNOS) in lipopolysaccharide (LPS)-activated murine macrophage RAW264 cells. 6-MITC showed a dose-dependent inhibition of LPS-induced nitric oxide (NO), iNOS mRNA and protein. LPS caused the c-Jun phosphorylation (a major component of AP-1) and IkappaB-alpha degradation. 6-MITC suppressed LPS-induced c-Jun phosphorylation, but did not inhibit IkappaB-alpha degradation. Cellular signaling analysis using MAPK-(U0126 for MEK1/2, SB203580 for p38 kinase and SP600125 for JNK) and Jak2-specific (AG490) inhibitors demonstrated that LPS stimulated iNOS expression via activating Jak2-mediated JNK, but not ERK and p38, pathway. 6-MITC suppressed iNOS expression through the inhibition of Jak2-mediated JNK signaling cascade with the attendant to AP-1 activation. In addition, the structure-activity study revealed that the inhibitory potency of methylsulfinyl isothiocyanates (MITCs) depended on the methyl chain length. These findings provide the molecular basis for the first time that 6-MITC is an effective agent to attenuate iNOS production.
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PMID:6-(Methylsulfinyl)hexyl isothiocyanate suppresses inducible nitric oxide synthase expression through the inhibition of Janus kinase 2-mediated JNK pathway in lipopolysaccharide-activated murine macrophages. 1613 49

6-(Methylsulfinyl)hexyl isothiocyanate (6-MITC) is a chemopreventive compound occurring in Wasabi (Wasabia japonica (Miq.) Matsumura), which is a very popular pungent spice in Japan. We investigated the effects of 6-MITC on the expression of cyclooxygenase-2 (COX-2) in lipopolysaccharide (LPS)-activated murine macrophage RAW264 cells. Treatment with 6-MITC suppressed LPS-mediated induction of COX-2 protein in a dose-dependent manner. Transfections with various COX-2 promoter reporter constructs revealed that the inhibitory effects of 6-MITC on COX-2 gene expression were directed by the core promoter elements including nuclear factor kappaB (NF-kappaB), CCAAT/enhancer-binding protein (C/EBP) and cyclic AMP-response element (CRE) sites. Western blotting analysis showed that 6-MITC inhibited LPS-induced activation of MAPK (ERK, p38 kinase and JNK) and transcriptional factors (CREB, c-Jun and C/EBPdelta) binding the core elements of COX-2 promoter, substantiating the involvement of these signal transduction pathways in the regulation of COX-2 expression by 6-MITC. Moreover, Western blotting experiments with MAPK-specific inhibitors (U0126 for MEK1/2, SB203580 for p38 kinase and SP600125 for JNK) demonstrated that 6-MITC suppressed LPS-induced COX-2 expression by blocking the activation of JNK-mediated AP-1 and ERK/p38 kinase-mediated CREB or C/EBPdelta. Finally, the structure-activity study revealed that the inhibitory potency of methylsulfinyl isothiocyanates (MITCs) depended on the methyl chain length. These findings demonstrate for the first time that 6-MITC is an effective agent to attenuate COX-2 production, and enhance our understanding of the anti-inflammation properties of 6-MITC.
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PMID:Inhibition of lipopolysaccharide-induced cyclooxygenase-2 transcription by 6-(methylsulfinyl) hexyl isothiocyanate, a chemopreventive compound from Wasabia japonica (Miq.) Matsumura, in mouse macrophages. 1625 55

Cytosolic phospholipase A2 (cPLA2) plays a pivotal role in mediating agonist-induced arachidonic acid (AA) release for prostaglandins (PG) synthesis induced by bacterial lipopolysaccharide (LPS) and cytokines. However, the intracellular signaling pathways mediating LPS-induced cPLA2 expression and PGE2 synthesis in canine tracheal smooth muscle cells (TSMCs) remains unknown. LPS-induced expression of cPLA2 and release of PGE2 was attenuated by inhibitors of tyrosine kinase (genistein), phosphatidylcholine-phospholipase C (D609), phosphatidylinositol-phospholipase C (U73122), PKC (GF109203X and staurosporine), removal of Ca2+ by BAPTA/AM plus EDTA, MEK1/2 (PD98059), p38 (SB202190), JNK (SP600125), and phosphatidylinositol 3-kinase (PI3-K; LY294002 and wortmannin). The involvement of MPAKs in LPS-induced responses was further confirmed by transfection of TSMCs with dominant negative mutants of ERK2 and p38. LPS-induced cPLA2 expression and PGE2 synthesis was inhibited by a selective NF-kappaB inhibitor (helenalin) and transfection with dominant negative mutants of NF-kappaB inducing kinase (NIK), IkappaB kinase (IKK)-alpha, and IKK-beta, consistent with that LPS-stimulated both IkappaB-alpha degradation and NF-kappaB translocation into nucleus in these cells. LPS-stimulated cPLA2 phosphorylation was inhibited by PD98059, GF109203X, and staurosporine, indicating the regulation by p42/p44 MAPK and PKC. Moreover, LPS-induced up-regulation of cPLA2 and COX-2 linked to PGE2 synthesis was inhibited by AACOCF3 (a selective cPLA2 inhibitor), implying the involvement of cPLA2 in these responses. These findings suggest that phosphorylation and expression of cPLA2 correlates with the release of PGE2 from LPS-challenged TSMCs, at least in part, mediated through MAPKs and NF-kappaB signaling pathways. LPS-mediated responses were modulated by PLC, Ca2+, PKC, tyrosine kinase, and PI3-K in TSMCs.
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PMID:Induction of cytosolic phospholipase A2 by lipopolysaccharide in canine tracheal smooth muscle cells: involvement of MAPKs and NF-kappaB pathways. 1627 65

Pro-inflammatory molecules induce glial activation and the release of potentially detrimental factors capable of generating oxidative damage, such as nitric oxide (NO) and superoxide anion (O2.-). Activated glial cells (astrocytes and microglia) are associated to the inflammatory process in neurodegenerative diseases. A strong inflammatory response could escape endogenous control becoming toxic to neurons and contributing to the course of the disease. We evaluated in a hippocampal cells-microglia co-culture model, if the pro-inflammatory condition induced by lipopolysaccharide + interferon-gamma (LPS+IFN-gamma) promoted damage directly or if damage was secondary to glial activation. In addition, we explored the effect of the anti-inflammatory cytokine transforming growth factor-beta1 (TGF-beta1), and pro-inflammatory cytokines, interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha) on the regulation of the inflammatory response of microglia. We found that LPS+IFN-gamma-induced damage on hippocampal cultures was dependent on the presence of microglial cells. In hippocampal cultures exposed to LPS+IFN-gamma, TGF-beta1 was induced whereas in microglial cell cultures LPS+IFN-gamma induced the secretion of IL-1beta. TGF-beta1 and IL-1beta but not TNF-alpha decreased the NO production by 70-90%. PD98059, an inhibitor of MAP kinase (MEK), reduced the IFN-gamma-induced NO production by 40%. TGF-beta and IL-1beta reduced the IFN-gamma induced phosphorylation of ERK1,2 by 60% and 40%, respectively. However, the effect of IL-1beta was observed at 30 min and that of TGF-beta1 only after 24 h of exposure. We propose that acting with different timing, TGF-beta1 and IL-1beta can modulate the extracellular signal-regulated kinase ERK1,2, as a common element for different transduction pathways, regulating the amplitude and duration of glial activation in response to LPS+IFN-gamma. Cross-talk among brain cells may be key for the understanding of inflammatory mechanisms involved in pathogenesis of neurodegenerative diseases.
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PMID:Pro- and anti-inflammatory cytokines regulate the ERK pathway: implication of the timing for the activation of microglial cells. 1637 22

The oncoprotein kinase Tpl2 plays an essential role in macrophage activation by the bacterial component lipopolysaccharide (LPS). In response to LPS stimulation, Tpl2 phosphorylates a downstream kinase, MEK1, leading to the activation of ERK signaling pathway. Recent studies demonstrate that the NF-kappaB1 precursor protein p105 functions as an inhibitor of Tpl2 and that the LPS-stimulated Tpl2 activation requires p105 degradation. However, how p105 inhibits the signaling function of Tpl2 is not completely understood. We show here that p105 does not inhibit the intrinsic kinase activity of Tpl2. When complexed with p105, Tpl2 remains catalytically active and uses p105 as a substrate. However, the p105-bound Tpl2 is unable to phosphorylate its physiological target, MEK1. These findings suggest that p105 functions as a competitive inhibitor of Tpl2 that blocks its access by MEK1.
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PMID:Phosphorylation of NF-kappaB1/p105 by oncoprotein kinase Tpl2: implications for a novel mechanism of Tpl2 regulation. 1644 10

The molecular mechanism of cytotoxic cytokine tumor necrosis factor alpha (TNFalpha) induction in microglia remains to be clarified. We have previously reported that p38 mitogen-activated protein kinase (p38MAPK) is an important signaling molecule for the induction of TNFalpha in lipopolysaccharide (LPS)-stimulated microglia. Recently, we have shown that c-Jun N-terminal kinase (JNK) is associated with the induction of TNFalpha. Furthermore, using an NFkappaB inhibitor (SN50), we discovered that activation of nuclear factor kappaB (NFkappaB) may also be linked to TNFalpha induction. We therefore examined the relationship between NFkappaB and the two MAPKs (p38MAPK and JNK) in the signaling cascade of TNFalpha induction in LPS-stimulated microglia. NFkappaB inhibitor SN50 decreased the induction of TNFalpha under the suppressed NFkappaB activation. However, SN50 was found to prevent the activation of MKK3/6-p38MAPK and MKK4-JNK pathways. On the other hand, the other NFkappaB inhibitor ammonium pyrrolidine dithiocarbamate (APDC) neither prevented the activation of p38MAPK and JNK nor inhibited TNFalpha induction in LPS-stimulated microglia, although it was confirmed to serve as an NFkappaB inhibitor. These results suggest that both MKK3/6-p38MAPK and MKK4-JNK pathways are important signaling cascades leading to the induction of TNFalpha in LPS-stimulated microglia, but that NFkappaB itself is not required for this induction.
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PMID:Nonparticipation of nuclear factor kappa B (NFkappaB) in the signaling cascade of c-Jun N-terminal kinase (JNK)- and p38 mitogen-activated protein kinase (p38MAPK)-dependent tumor necrosis factor alpha (TNFalpha) induction in lipopolysaccharide (LPS)-stimulated microglia. 1645 91

MNSFbeta is a ubiquitously expressed member of the ubiquitin-like family that has been implicated in various biological functions. Previous studies have demonstrated that MNSFbeta covalently binds to intracellular proapoptotic protein Bcl-G in mitogen-activated murine T cells. In this study, we further investigated the intracellular mechanism of action of MNSFbeta in macrophage cell line, Raw 264.7 cells. We present evidence that MNSFbeta.Bcl-G complex associates with ERKs in non-stimulated Raw 264.7. We found that MNSFbeta.Bcl-G directly bound to ERKs and inhibited ERK activation by MEK1. In Raw 264.7 cells treated with MNSFbeta small interfering RNA (siRNA) lipopolysaccharide (LPS)-induced ERK1/2 activation was enhanced and LPS-induced JNK and p38 activation was unaffected. SiRNA-mediated knockdown of MNSFbeta increased tumor necrosis factor alpha (TNFalpha) expression at mRNA and protein levels in LPS-stimulated Raw 264.7 cells. Finally, we found that transfection with MNSFbeta expression construct resulted in a significant inhibition of LPS-induced ERK activation and TNFalpha production. Co-transfection experiments with MNSFbeta and Bcl-G greatly enhanced this inhibition. Collectively, these findings indicate that MNSFbeta might be implicated in the macrophage response to LPS.
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PMID:The ubiquitin-like protein MNSFbeta regulates ERK-MAPK cascade. 1662 90

Interferongamma inducible protein-10 (IP10 or CXCL10), a Th-1 affiliated chemokine, is expressed by activated glial cells and may contribute to the trafficking of immune cells in the inflamed central nervous system. This study examines the regulation of the expression of this chemokine in cultured microglial cells focusing on the roles of mitogen-activated protein (MAP) kinase cascades. Exposure of a mouse microglial cell line, BV-2, to lipopolysaccharide (LPS) and IFNgamma led to an induction of IP10 mRNA and protein as determined by RT-PCR and ELISA, respectively. This induction was suppressed by pharmacological inhibitors of p38 MAPK (i.e., SB203580) and c-Jun N-terminal kinase (JNK, SP600125), suggesting the involvement of the two kinases in IP10 expression. LPS also induced the activity of an IP10 promoter reporter (luciferase) construct transfected into BV-2 cells in a MAP kinase- and NFkappaB-dependent manner. The use of deletion constructs revealed that the kinase-targeted sequences were within the region between -533 bp and -332 bp upstream of the transcriptional start site. Co-transfection of IP10 luciferase with the active forms of the upstream kinases in the MAP kinase cascades, i.e., MAPK kinase-3 (MKK3), MKK6 (the immediately upstream activators of p38 kinase) and a MAP3K, i.e., TGFbeta-activated kinase-1 (TAK1), produced a marked stimulation of the promoter activity. The results of this study indicate that the MAP kinase cascades prominently regulate IP10 gene expression in microglial cells.
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PMID:MAP kinase regulation of IP10/CXCL10 chemokine gene expression in microglial cells. 1663 81

The lipopolysaccharide (LPS) of Gram-negative bacteria induces the expression of cytokines and proinflammatory genes via the TLR4 signaling pathway in diverse cell types. The purpose of the present study was to test the hypothesis that the nasopharynx epithelial cells (NECs) could recognize and respond to LPS. The underlying molecular mechanisms were further elucidated in the NEC line 5-8F for its ability to activate the NFkappaB and TNF-alpha reporter genes, in response to LPS. After LPS stimulation, the TNF-alpha promoter activity and the relevant production of TNF-alpha were significantly increased in 5-8F cells. Moreover, LPS activated NFkappaB p65, ERK1/2 and JNK1/2 and induced their translocation to the nucleus. Western blot analysis showed that the expression of NFkappaB p65, MEK1, ERK1/2, JNK1/2, phospho-ERK1/2 and phospho-JNK1/2 proteins also was increased in NEC 5-8F cells, following the LPS stimulation. Additionally, the expression of TLR1-6, MD2 and CD14 was examined by RT-PCR, and the CD14 expression was determined by flow cytometry analysis. We demonstrated that the expression of CD14, TLR4 and MD2 was crucial for the NEC responses to LPS. In conclusion, our results provide novel mechanisms for the response of nasopharnyx epithelial cells to LPS stimulation, through NFkappaB and MAPKs signaling pathways.
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PMID:Lipopolysaccharide (LPS) regulates TLR4 signal transduction in nasopharynx epithelial cell line 5-8F via NFkappaB and MAPKs signaling pathways. 1667 17

Neuroinflammatory diseases are associated with increased production of matrix metalloproteinase-9 (MMP-9) and excessive generation of nitric oxide (NO). NO has been reported to have variable effects on MMP-9 gene expression and activation in various cell types. In the present study, we investigated the effect of NOon MMP-9 expression in primary cortical astrocytes. Zymography and real-time PCR showed that lipopolysaccharide (LPS) dramatically increased latent MMP-9 gelatinolytic activity and MMP-9 mRNA expression. By using the NO donor DETA NONOate, we observed a dose-dependent inhibition of MMP-9 induction by LPS. Active forms of MMP-9 were not found by zymography after NO treatment. The MEK1/2 inhibitor U0126 completely inhibited LPS-induced MMP-9, which was partially inhibited by the p38 MAPK inhibitor SB203580. NO had no effect on LPS-stimulated ERK1/2 and p38 MAPK activation, suggesting that the inhibitory action of NO occurs downstream of MAPK cascades. Real-time PCR analysis showed that NO accelerated the degradation of MMP-9 mRNA after LPS induction. Western blotting and pull-down assay demonstrated that NO increased AUF-1 expression as well as its specific binding to the MMP-9 gene 3'-untranslated region. Knockdown of AUF-1 with siRNA partially reversed the inhibitory action of NO on LPS-stimulated MMP-9 induction. We conclude that NO does not activate MMP-9 in astrocyte cultures but reduces LPS-induced MMP-9 expression via accelerating MMP-9 mRNA degradation, which is partially mediated by AUF-1. Our results suggest that elevated NO concentrations may suppress MMP-9 and restrict the inflammatory response in neurodegenerative diseases.
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PMID:AUF-1 mediates inhibition by nitric oxide of lipopolysaccharide-induced matrix metalloproteinase-9 expression in cultured astrocytes. 1668 34


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