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

---

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

Sulfur mustard (SM) is a strong vesicant that has been used as a chemical warfare agent. To understand the molecular mechanisms that underlie the inflammatory skin reaction in response to SM, we analyzed the activation pattern of the NF-kappaB and mitogen-activated protein kinase (MAPK) pathways. Keratinocytes responded with an induction of the canonical NF-kappaB pathway, including activation of IkappaB kinase 2, followed by phosphorylation and degradation of IkappaBalpha and of the transactivating subunit RelA at Ser536. The biphasic NF-kappaB response was strictly dependent on the transactivating subunit RelA, as demonstrated by keratinocytes lacking RelA. Parallel to NF-kappaB activation, we observed an induction of the Raf-1/MEK1/2/ERK1/2/MSK1 and MKK3/6/p38/MSK1 pathways. Although mitogen and stress-activated kinase 1 has been described as a RelA kinase with Ser276 as its target, this site remained unphosphorylated in response to SM. A further MAPK pathway induced by SM was the MKK4/7/JNK1/2 pathway, which resulted in phosphorylation of the transcription factor activating transcription factor-2, but not c-Jun. Our results indicate that SM induces a complex cellular response in keratinocytes, with the activation of three MAPK pathways and the NF-kappaB pathway.
...
PMID:Role of NF-kappaB/RelA and MAPK pathways in keratinocytes in response to sulfur mustard. 1820 59

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

KIR2DL4 (2DL4) is a member of the killer cell Ig-like receptor (KIR) family in human NK cells. It can stimulate potent cytokine production and weak cytolytic activity in resting NK cells, but the mechanism for 2DL4-mediated signaling remains unclear. In this study we characterized the signaling pathways stimulated by 2DL4 engagement. In a human NK-like cell line, KHYG-1, cross-linking of 2DL4 activated MAPKs including JNK, ERK, and p38. Furthermore, 2DL4 cross-linking resulted in phosphorylation of IkappaB kinase beta (IKKbeta) and the phosphorylation and degradation of IkappaBalpha, which indicate activation of the classical NF-kappaB pathway. Engagement of 2DL4 was also shown to activate the transcription and translation of a variety of cytokine genes, including TNF-alpha, IFN-gamma, MIP1alpha, MIP1beta, and IL-8. Pharmacological inhibitors of JNK, MEK1/2 and p38, blocked IFN-gamma, IL-8, and MIP1alpha production, suggesting that MAPKs are regulating 2DL4-mediated cytokine production in a nonredundant manner. Activation of both p38 and ERK appear to be upstream of the stimulation of NF-kappaB. Mutation of a transmembrane arginine in 2DL4 to glycine (R/G mutant) abrogated FcepsilonRI-gamma association, as well as receptor-mediated cytolytic activity and calcium responses. Surprisingly, the R/G mutant still activated MAPKs and the NF-kappaB pathway and selectively stimulated the production of MIP1alpha, but not that of IFN-gamma or IL-8. In conclusion, we provide evidence that the activating functions of 2DL4 can be compartmentalized into two distinct structural modules: 1) through transmembrane association with FcepsilonRI-gamma; and 2) through another receptor domain independent of the transmembrane arginine.
...
PMID:KIR2DL4 differentially signals downstream functions in human NK cells through distinct structural modules. 1829 14

Lyme borreliosis is a spirochetal infection caused by the Borrelia burgdorferi sensu lato complex that can proceed towards an inflammatory joint manifestation known as Lyme arthritis. Production of chemokines orchestrating neutrophil infiltration is supposed to be key to early arthritic pathogenesis. Using PMA-differentiated macrophage-like THP-1 (mTHP-1) cells we identified by antibody array methodology or mRNA analysis IL-8, GRO-alpha, NAP-2, and SDF-1alpha as being among those chemokines that are upregulated by bacterial lysates obtained from B. burgdorferi. Based on these observations, we set out to characterize in detail mechanisms mediating IL-8 release in this cellular model. TLR2 blocking antibodies, analysis of p65 translocation, and electromobility-shift analysis revealed activation of the TLR2/NF-kappaB axis by B. burgdorferi. The functional importance of this pathway was substantiated by suppression of IL-8 after inhibition of IkappaB kinase. Notably, MAP kinases, specifically the MEK1/2-ERK1/2 pathway, were essential for IL-8 secretion. Those data were confirmed by using freshly isolated adherent peripheral blood mononuclear cells. On the contrary, B. burgdorferi-induced IL-8 in mTHP-1 was unlikely related to flagellin, alpha3beta1-integrin signaling, lipopolysaccharide, bacterial DNA, NOD1/NOD2 agonists, or to intermediate production of IL-1beta and TNF-alpha. Induction of IL-8 by B. burgdorferi was not due to amplification of constitutive AP-1 DNA-binding activity detectable in mTHP-1 cells. Data presented herein validate that TLR2, particularly on mTHP-1 cells, holds a central position in mediating IL-8 secretion associated with extracellular B. burgdorferi and beyond that suggest inhibition of IkappaB kinase and MEK1/2 kinases as promising pharmacological strategies aiming at IL-8 in early Lyme arthritis.
...
PMID:Systematic analysis highlights the key role of TLR2/NF-kappaB/MAP kinase signaling for IL-8 induction by macrophage-like THP-1 cells under influence of Borrelia burgdorferi lysates. 1857 57

Cytosolic phospholipase A2 (cPLA2) plays a pivotal role in mediating agonist-induced arachidonic acid release for prostaglandin (PG) synthesis during stimulation with interleukin-1beta (IL-1beta). However, the mechanisms underlying IL-1beta-induced cPLA2 expression and PGE2 synthesis by canine tracheal smooth muscle cells (CTSMCs) have not been defined. IL-1beta induced cPLA2 protein and mRNA expression, PGE2 production, and phosphorylation of p42/p44 MAPK, p38 MAPK (ATF2), and JNK (c-Jun) in a time- and concentration-dependent manner, determined by Western blotting, RT-PCR, and ELISA, which was attenuated by the inhibitors of MEK1/2 (U0126), p38 MAPK (SB202190), and JNK (SP600125), or transfection with dominant negative mutants of MEK1/2, p38, and JNK, respectively. Furthermore, IL-1beta-induced cPLA2 expression and PGE2 synthesis was inhibited by a selective NF-kappaB inhibitor (helenalin) or transfection with dominant negative mutants of NF-kappaB inducing kinase (NIK), IkappaB kinase (IKK)-alpha, and IKK-beta. Consistently, IL-1beta stimulated both IkappaB-alpha degradation and NF-kappaB translocation into nucleus in these cells. NF-kappaB translocation was blocked by helenalin, but not by U0126, SB202190, and SP600125. MAPKs together with NF-kappaB-activated p300 recruited to cPLA2 promoter thus facilitating the binding of NF-kappaB to cPLA2 promoter region and expression of cPLA2 mRNA. IL-1beta-induced cPLA2 expression and PGE2 production was inhibited by actinomycin D and cycloheximide, indicating the involvement of transcriptional and translational events in these responses. These results suggest that in CTSMCs, IL-1beta-induced cPLA2 expression and PGE2 synthesis was independently mediated through activation of MAPKs and NF-kappaB pathways and was connected to p300 recruitment and activation.
...
PMID:Involvement of MAPKs, NF-kappaB and p300 co-activator in IL-1beta-induced cytosolic phospholipase A2 expression in canine tracheal smooth muscle cells. 1870 82

JNK is a key regulator of matrix metalloproteinase production in rheumatoid arthritis. It is regulated by two upstream kinases known as MKK4 and MKK7. Previous studies demonstrated that only MKK7 is required for cytokine-mediated JNK activation and matrix metalloproteinase expression in cultured fibroblast-like synoviocytes (FLS). However, the functions of MKK4 and MKK7 in synoviocyte innate immune responses have not been determined. TNF, peptidoglycan (PGN), and LPS stimulation led to higher and more prolonged MKK7 phosphorylation compared with MKK4 in FLS. However, this pattern was reversed in poly(I-C) stimulated cells. siRNA knockdown studies showed that TNF, PGN, and LPS-induced JNK and c-Jun phosphorylation are MKK7 dependent, while poly(I-C) responses require both MKK4 and MKK7. Poly(I-C)-induced expression of IP-10, RANTES, and IFN-beta mRNA was decreased in MKK4- or MKK7-deficient FLS. However, MKK4 and MKK7 deficiency did not affect phosphorylation of IkappaB kinase-related kinases in the TLR3 signaling pathway. MKK7, but not MKK4 deficiency, significantly decreased poly(I-C)-mediated IRF3 dimerization, DNA binding, and IFN-sensitive response element-mediated gene transcription. These results were mimicked by the JNK inhibitor SP600125, indicating that JNK can directly phosphorylate IRF3. In contrast, deficiency of either MKK4 or MKK7 decreased AP-1 transcriptional activity. Therefore, JNK is differentially regulated by MKK4 and MKK7 depending on the stimulus. MKK7 is the primary activator of JNK in TNF, LPS, and PGN responses. However, TLR3 requires both MKK4 and MKK7, with the former activating c-Jun and the latter activating both c-Jun and IRF3 through JNK-dependent mechanisms.
...
PMID:Synoviocyte innate immune responses: I. Differential regulation of interferon responses and the JNK pathway by MAPK kinases. 1871 96

Lipopolysaccharide (LPS), a glycolipid component of the outer membrane of Gram-negative bacteria, is a potent initiator of the innate immune response of the macrophage. LPS triggers downstream signaling by selectively recruiting and activating proteins in cholesterol-rich membrane microdomains called lipid rafts. We applied proteomics analysis to macrophage detergent-resistant membranes (DRMs) during an LPS exposure time course in an effort to identify and validate novel events occurring in macrophage rafts. Following metabolic incorporation in cell culture of heavy isotopes of amino acids arginine and lysine ([(13)C(6)]Arg and [(13)C(6)]Lys) or their light counterparts, a SILAC (stable isotope labeling with amino acids in cell culture)-based quantitative, liquid chromatography-tandem mass spectrometry proteomics approach was used to profile LPS-induced changes in the lipid raft proteome of RAW 264.7 macrophages. Unsupervised network analysis of the proteomics data set revealed a marked representation of the ubiquitin-proteasome system as well as changes in proteasome subunit composition following LPS challenge. Functional analysis of DRMs confirmed that LPS causes selective activation of the proteasome in macrophage rafts and proteasome inactivation outside of rafts. Given previous reports of an essential role for proteasomal degradation of IkappaB kinase-phosphorylated p105 in LPS activation of ERK mitogen-activated protein kinase, we tested for a role of rafts in compartmentalization of these events. Immunoblotting of DRMs revealed proteasome-dependent activation of MEK and ERK specifically occurring in lipid rafts as well as proteasomal activity upon raft-localized p105 that was enhanced by LPS. Cholesterol extraction from the intact macrophage with methyl-beta-cyclodextrin was sufficient to activate ERK, recapitulating the LPS-IkappaB kinase-p105-MEK-ERK cascade, whereas both it and the alternate raft-disrupting agent nystatin blocked subsequent LPS activation of the ERK cascade. Taken together, our findings indicate a critical, selective role for raft compartmentalization and regulation of proteasome activity in activation of the MEK-ERK pathway.
...
PMID:Quantitative proteomics analysis of macrophage rafts reveals compartmentalized activation of the proteasome and of proteasome-mediated ERK activation in response to lipopolysaccharide. 1881 23

Scatter factor (SF) (hepatocyte growth factor) is a pleiotrophic cytokine that accumulates in tumors, where it may induce invasion, angiogenesis, and chemoresistance. We have studied the mechanisms by which SF and its receptor (c-Met) protect cells against the DNA-damaging agent adriamycin (ADR) as a model for chemoresistance of SF/c-Met-overexpressing tumors. Previous studies identified a phosphatidylinositol 3-kinase/c-Akt/Pak1/NF-kappaB cell survival pathway in DU-145 prostate cancer and Madin-Darby canine kidney epithelial cells. Here we studied Src signaling pathways involved in SF cell protection. Src enhanced basal and SF stimulated NF-kappaB activity and SF protection against ADR, in a manner dependent upon its kinase and Src homology 3 domains; and endogenous Src was required for SF stimulation of NF-kappaB activity and cell protection. The ability of Src to enhance SF stimulation of NF-kappaB activity was due, in part, to its ability to stimulate Akt and IkappaB kinase activity; and Src-mediated stimulation of NF-kappaB was due, in part, to a Rac1/MKK3/6/p38 pathway and was Akt-dependent. SF caused the activation of Src and the Rac1 effector Pak1. Furthermore, SF induced activating phosphorylations of MKK3, MKK6, and p38 within the c-Met signalsome in an Src-dependent manner. The NF-kappaB-inducing kinase was found to act downstream of TAK1 (transforming growth factor-beta-activated kinase 1) as a mediator of SF- and Src-stimulated NF-kappaB activity. Finally, the Src/Rac1/MKK3/6/p38 and Src/TAK1/NF-kappaB-inducing kinase pathways exhibited cross-talk at the level of MKK3. These findings delineate some novel signaling pathways for SF-mediated resistance to ADR.
...
PMID:Role of Src signal transduction pathways in scatter factor-mediated cellular protection. 1904 46

Various genotoxic agents cause monoubiquitination of NEMO/IKKgamma-the regulatory subunit of IkappaB kinase (IKK) complex-in the nucleus. Ubiquitinated NEMO exits from the nucleus and forms a complex with the IKK catalytic subunits IKKalpha and IKKbeta, resulting in IKK activation and, ultimately, nuclear factor-kappaB (NF-kappaB) activation. Thus, NEMO ubiquitination is a prerequisite for IKK-dependent activation of NF-kappaB. However, the IKK activation mechanism is unknown and the NEMO-ubiquitinating E3 enzyme has not been identified. We found that inhibitors of apoptosis protein (IAP) regulate genotoxic stress-induced NF-kappaB activation at different levels. XIAP mediates activation of the upstream IKK kinase, TAK1, and couples activated TAK1 to the IKK complex. This XIAP-dependent event occurs in response to camptotechin or etoposide/VP16; however, XIAP is dispensable for activation of NF-kappaB by doxorubicin, which engages a MEK-ERK pathway to activate IKK. We also show that cIAP1 mediates NEMO ubiquitination and cIAP2 regulates an event downstream of NEMO ubiquitination. Our study highlights nonredundant cooperative contributions of IAPs to antiapoptotic NF-kappaB activation by genotoxic signals beyond their classic caspase inhibitory functions.
...
PMID:cIAP1, cIAP2, and XIAP act cooperatively via nonredundant pathways to regulate genotoxic stress-induced nuclear factor-kappaB activation. 1922 49

It has been shown that ultrasound (US) stimulation accelerates fracture healing in the animal models and non-operatively clinical uses. Nitric oxide (NO) is a crucial early mediator in mechanically induced bone formation. Here we found that US-mediated inducible nitric oxide synthase (iNOS) expression was attenuated by Ras inhibitor (manumycin A), Raf-1 inhibitor (GW5074), MEK inhibitor (PD98059), NF-kappaB inhibitor (PDTC), and IkappaB protease inhibitor (TPCK). US-induced Ras activation was inhibited by manumycin A. Raf-1 phosphorylation at Ser(338) by US was inhibited by manumycin A and GW5074. US-induced MEK and ERK activation was inhibited by manumycin A, GW5074, and PD98059. Stimulation of preosteoblasts with US activated IkappaB kinase alpha/beta (IKK alpha/beta), IkappaBalpha phosphorylation, p65 phosphorylation at Ser(276), p65, and p50 translocation from the cytosol to the nucleus, and kappaB-luciferase activity. US-mediated an increase of IKK alpha/beta, IkappaBalpha, and p65 phosphorylation, kappaB-luciferase activity and p65 and p50 binding to the NF-kappaB element was inhibited by manumycin A, GW5074, and PD98059. Our results suggest that US increased iNOS expression in preosteoblasts via the Ras/Raf-1/MEK/ERK/IKKalphabeta and NF-kappaB signaling pathways.
...
PMID:Ultrasound stimulates NF-kappaB activation and iNOS expression via the Ras/Raf/MEK/ERK signaling pathway in cultured preosteoblasts. 1928 77


<< Previous 1 2 3 4 5 6 Next >>

---