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)

A number of different agents, such as growth factors, cytokines and phorbol esters have been shown to modulate trabecular meshwork cell function. These studies were designed to evaluate the role extracellular signal-regulated kinase (ERK) pathway plays in mediating the responses to platelet-derived growth factor-BB (PDGF-BB) and phorbol 12-myristate 13-acetate (PMA) in trabecular meshwork cells. The human trabecular meshwork cell line, HTM-3, and the bovine trabecular meshwork (BTM) cells were treated with either PDGF-BB or PMA and the activation of ERK 1/2 evaluated. The effects of the MAP kinase kinase (MEK) inhibitor U0126, and the PKC inhibitor chelerythrine on ERK 1/2 were also determined. In a separate group of experiments, cells were treated with PDGF-BB or PMA and the secretion of matrix metalloproteinase-2 (MMP-2) evaluated. The addition of PDGF-BB or PMA produced time- and dose-dependent activation of ERK 1/2. Pretreatment with U0126 or chelerythrine significantly reduced ERK 1/2 activation induced by PDGF-BB or PMA. The addition of PDGF-BB or PMA stimulated the secretion of MMP-2. This secretory response was inhibited by pretreatment with the MEK inhibitor U0126. In trabecular meshwork cells, PDGF-BB and PMA activate ERK 1/2 by a PKC-dependent mechanism. Activation of ERK 1/2 by these agents in trabecular meshwork cells leads to the secretion of MMP-2. These studies provide evidence that ERK pathway is an important mechanism for integrating various signals that regulate trabecular function.
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PMID:Activation of extracellular signal-regulated kinase in trabecular meshwork cells. 1142 60

Autocrine motility factor/phosphohexose isomerase (AMF/PHI) is a cytokine that is linked to tumor invasion and metastasis. In hepatocellular carcinoma (HCC) tissues, hepatoma cells produce AMF/PHI and its receptor, Mr 78,000 glycoprotein (gp78), is strongly detected in hepatoma cells invading into the stroma and tumor thrombi in the portal vein. Here, we investigated the mechanism of hepatoma cell invasion through Matrigel induced by AMF/PHI using 3 hepatoma cell lines. Production of AMF/PHI, phosphorylation of MEK1/2, and Rho activity were investigated by immunoblotting. Expression of AMF/PHI and gp78 was observed by confocal fluorescence microscopy. The influence of AMF/PHI on activated integrin beta1 subunit expression was evaluated by flow cytometry. Changes in invasion, adhesion, and motility induced by AMF/PHI were evaluated using chemoinvasion, adhesion, and phagokinetic track motility assays. The effect of AMF/PHI on matrix metalloproteinase (MMP) secretion was evaluated by gelatin zymography. Hepatoma cells produced AMF/PHI and expressed gp78. Although AMF/PHI was ubiquitously detected, gp78 was strongly expressed in migrating cells. AMF/PHI induced up-regulation of activated integrin beta1 subunit expression. AMF/PHI stimulated hepatoma cell invasion through Matrigel, and stimulated the adhesion, motility, and MMP-2 secretion of hepatoma cells. The latter effects were suppressed by the function-blocking antibody for integrin beta1 subunit. AMF/PHI also enhanced Rho activity and the phosphorylation of MEK1 and MEK 2. Our results indicate that AMF/PHI enhances hepatoma cell invasion through Matrigel in an autocrine manner by stimulating the adhesion, motility, and MMP-2 secretion of these cells through activation of beta1 integrins.
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PMID:Autocrine motility factor enhances hepatoma cell invasion across the basement membrane through activation of beta1 integrins. 1143 35

Cell adhesion to the extracellular matrix appears to trigger a cascade of intracellular signalings. We have previously shown that treatment of ovarian cancer cells, NOM1, with fibronectin (FN) stimulated matrix metalloproteinase (MMP)-9 secretion and thereby activated the invasiveness of cells via the FAK/Ras signaling pathway. By use of chemical inhibitors, we investigated the downstream effectors critical for FN-dependent secretion of MMP-9. Treatment of cells with MEK1 inhibitors, U0126 and PD98059, dramatically suppressed the secretion of MMP-9 activated by FN. Similarly, P1-3 kinase inhibitors, Wortmannin and LY294002, strongly suppressed the FN-dependent secretion of MMP-9 together with the inhibition of Akt activation. In contrast, a specific PKC inhibitor (GF109203X) showed no inhibitory effect on the FN-dependent MMP-9 secretion. Moreover, we found that both the MEK1 inhibitor and the P13-K inhibitor, but not the PKC inhibitor, strongly suppressed the invasiveness of NOM1 cells. Taken together, our results suggest that activation of dual signaling pathways, MEKI-MAPK and P13K-Akt, is required for the FN-dependent activation of MMP-9 secretion. Our results suggest the importance of these signaling molecules as a chemotherapeutic target for cancer.
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PMID:Fibronectin activates matrix metalloproteinase-9 secretion via the MEK1-MAPK and the PI3K-Akt pathways in ovarian cancer cells. 1146 75

Elevated focal adhesion kinase (FAK) expression in human tumor cells has been correlated with an increased cell invasion potential. In cell culture, studies with FAK-null fibroblasts have shown that FAK function is required for cell migration. To determine the role of elevated FAK expression in facilitating epidermal growth factor (EGF)-stimulated human adenocarcinoma (A549) cell motility, antisense oligonucleotides were used to reduce FAK protein expression >75%. Treatment of A549 cells with FAK antisense (ISIS 15421) but not a mismatched control (ISIS 17636) oligonucleotide resulted in reduced EGF-stimulated p130(Cas)-Src complex formation, c-Jun NH(2)-terminal kinase (JNK) activation, directed cell motility, and serum-stimulated cell invasion through Matrigel. Because residual FAK protein in ISIS 15421-treated A549 cells was highly phosphorylated at the Tyr-397/Src homology (SH)2 binding site, expression of the FAK COOH-terminal domain (FRNK) was also used as an inhibitor of FAK function. Adenoviral-mediated infection and expression of FRNK promoted FAK dephosphorylation at Tyr-397, resulted in reduced EGF-stimulated JNK as well as extracellular-regulated kinase 2 (ERK2) kinase activation, inhibited matrix metalloproteinase-9 (MMP-9) secretion, and potently blocked both random and EGF-stimulated A549 cell motility. Equivalent expression of a FRNK (S-1034) point-mutant that did not promote FAK dephosphorylation also did not affect EGF-stimulated signaling or cell motility. Dose-dependent reduction in EGF-stimulated A549 motility was observed with the PD98059 MEK1 inhibitor and the batimastat (BB-94) inhibitor of MMP activity, but not with the SB203580 inhibitor of p38 kinase. Finally, comparisons between normal, FAK-null, and FAK-reconstituted fibroblasts revealed that FAK enhanced EGF-stimulated JNK and ERK2 kinase activation that was required for cell motility. These data indicate that FAK functions as an important signaling platform to coordinate EGF-stimulated cell migration in human tumor cells and support a role for inhibitors of FAK expression or activity in the control of neoplastic cell invasion.
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PMID:Inhibition of focal adhesion kinase expression or activity disrupts epidermal growth factor-stimulated signaling promoting the migration of invasive human carcinoma cells. 1158 39

In response to vascular injury, smooth muscle cells migrate from the media into the intima, where they contribute to the development of neointimal lesions. Increased matrix metalloproteinase (MMP) expression contributes to the migratory response of smooth muscle cells by releasing them from their surrounding extracellular matrix. MMPs may also participate in the remodeling of extracellular matrix in vascular lesions that could lead to plaque weakening and subsequent rupture. Neurotrophins and their receptors, the Trk family of receptor tyrosine kinases, are expressed in neointimal lesions, where they induce smooth muscle cell migration. We now report that nerve growth factor (NGF)-induced activation of the TrkA receptor tyrosine kinase induces MMP-9 expression in both primary cultured rat aortic smooth muscle cells and in a smooth muscle cell line genetically manipulated to express TrkA. The response to NGF was specific for MMP-9 expression, as the expression of MMP-2, MMP-3, or the tissue inhibitor of metalloproteinase-2 was not changed. Activation of the Shc/mitogen-activated protein kinase pathway mediates the induction of MMP-9 in response to NGF, as this response is abrogated in cells expressing a mutant TrkA receptor that does not bind Shc and by pretreatment of cells with the MEK-1 inhibitor, U0126. Thus, these results indicate that the neurotrophin/Trk receptor system, by virtue of its potent chemotactic activity for smooth muscle cells and its ability to induce MMP-9 expression, is a critical mediator in the remodeling that occurs in the vascular wall in response to injury.
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PMID:Nerve growth factor activation of Erk-1 and Erk-2 induces matrix metalloproteinase-9 expression in vascular smooth muscle cells. 1169 9

Here, we have examined the role of distinct MAPK pathways in the regulation of collagenase-1 (matrix metalloproteinase (MMP)-1) and stromelysin-1 (MMP-3) expression by human skin fibroblasts. Tumor necrosis factor-alpha rapidly and transiently activated ERK1/2 and JNK in fibroblasts, whereas the activation of p38 MAPK was more persistent. Inhibition of p38 activity by SB203580 markedly (by 80-90%) inhibited induction of MMP-1 and MMP-3 expression by tumor necrosis factor-alpha, whereas blocking the activation of ERK1/2 by PD98059 had no effect. Activation of endogenous ERK1/2 by adenovirus-mediated transfer of constitutively active MEK1 resulted in potent induction of MMP-1 and MMP-3 expression. Activation of endogenous or adenovirally expressed p38 alpha by adenovirally delivered constitutively active MKK3b and MKK6b also enhanced MMP-1 and MMP-3 expression and augmented the up-regulatory effect of ERK1/2 activation on the expression of these MMPs. Activation of ERK1/2 resulted in induction of c-jun, junB, and c-fos expression, whereas activation of p38 alone had no effect. In contrast, activation of p38 alpha resulted in marked stabilization of MMP-1 and MMP-3 mRNAs. These results identify two distinct and complementary signaling mechanisms mediating induction of MMP-1 and MMP-3 expression in dermal fibroblasts: AP-1-dependent transcriptional activation via the ERK1/2 pathway and AP-1-independent enhancement via p38 alpha MAPK by mRNA stabilization. It is conceivable that both modes of action play an important role in controlling the proteolytic phenotype of fibroblasts, e.g. in wound repair and tumor invasion.
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PMID:Activation of p38 alpha MAPK enhances collagenase-1 (matrix metalloproteinase (MMP)-1) and stromelysin-1 (MMP-3) expression by mRNA stabilization. 1206 Jun 61

Our previous data showed that nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit matrix metalloproteinase-2 (MMP-2) expression via repression of gene transcription in lung cancer cells. In this study, we investigate the molecular mechanism by which NSAIDs inhibit MMP-2. Promoter deletion and mutation analysis indicate that NSAIDs act via the Sp1 transcription factor binding site located between -91 and -84 in the MMP-2 promoter to suppress gene expression. Electrophoretic mobility shift assays show that Sp1 and Sp3 proteins constitutively bind to this consensus sequence and overexpression of Sp1 may enhance MMP-2 expression. NSAID treatment reduces Sp1 DNA binding activity and phosphorylation and attenuates MMP-2 expression. We also investigate the signaling pathway that mediates the effect of NSAIDs. Our results suggest that ERKs are involved in this process. First, NSAIDs suppress basal and serum-stimulated ERK activity. Second, a MEK inhibitor PD98059 inhibits MMP-2 promoter activity and Sp1 phosphorylation. Third, overexpression of constitutively active MEK1 stimulates Sp1 phosphorylation and MMP-2 promoter activity and antagonizes the inhibition of NSAIDs. Collectively, our data suggest that NSAIDs inhibit MMP-2 by blocking ERK/Sp1-mediated transcription.
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PMID:Nonsteroidal anti-inflammatory drugs inhibit matrix metalloproteinase-2 via suppression of the ERK/Sp1-mediated transcription. 1208 91

Serotonin (5-hydroxytryptamine; 5-HT), acting via the 5-HT(2A) receptor, up-regulates the transcription and production of interstitial collagenase (matrix metalloproteinase-13; MMP-13), a critical enzyme responsible for maintaining the integrity of the uterus, after parturition. Serotonin treatment of rat uterine myometrial smooth muscle cells induced inositol phosphate (IP) turnover, which was abolished by the 5-HT(2A) receptor-specific antagonists ketanserin and spiperone. The phospholipase C (PLC) inhibitors and D609 attenuated serotonin-mediated-IP turnover with a corresponding inhibition of MMP-13 protein production. Subsequent recovery of both MMP-13 protein expression and IP generation was seen following the removal of D609. Protein kinase C (PKC) activators, the diacylglycerol analogue 1,2-dioctanoyl-sn-glycerol and phorbol myristate acetate (PMA), mimicked the effect of serotonin on MMP-13 protein expression; prolonged PMA treatment (which down-regulates PKC) lowered MMP-13 protein levels. The PKC-specific inhibitors bisindolylmaleimide I, calphostin C, CGP 41251, and the PKCdelta-selective inhibitor rottlerin were able to suppress serotonin up-regulation of MMP-13. Furthermore, the mitogen-activated protein kinase kinase (MEK) inhibitor PD98059 blocked serotonin-dependent activation of p44/42 MAPK (pERK1/2), a downstream effector of PKC and also down-regulated MMP-13 protein expression. Similarly, calphostin C and rottlerin depressed activation of p44/42 MAPK. From these studies, serotonin, binding through the 5-HT(2A) receptor, initiates a signaling cascade whereby stimulation of PLC leads to the activation of PKC and subsequently the ERK1/2 pathway, which ultimately results in MMP-13 production.
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PMID:Serotonin-induced MMP-13 production is mediated via phospholipase C, protein kinase C, and ERK1/2 in rat uterine smooth muscle cells. 1221 12

The goals of this study were 2-fold: 1) to determine whether stimulation of Eph B4 receptors promotes microvascular endothelial cell migration and/or proliferation, and 2) to elucidate signaling pathways involved in these responses. The human endothelial cells used possessed abundant Eph B4 receptors with no endogenous ephrin B2 expression. Stimulation of these receptors with ephrin B2/Fc chimera resulted in dose- and time-dependent phosphorylation of Akt. These responses were inhibited by LY294002 and ML-9, blockers of phosphatidylinositol 3-kinase (PI3K) and Akt, respectively. Eph B4 receptor activation increased proliferation by 38%, which was prevented by prior blockade with LY294002, ML-9, and inhibitors of protein kinase G (KT5823) and MEK (PD98059). Nitrite levels increased over 170% after Eph B4 stimulation, indicating increased nitric oxide production. Signaling of endothelial cell proliferation appears to be mediated by a PI3K/Akt/endothelial nitric-oxide synthase/protein kinase G/mitogen-activated protein kinase cascade. Stimulation with ephrin B2 also increased migration by 63% versus controls. This effect was inhibited by blockade with PP2 (Src inhibitor), LY294002 or ML-9 but was unaffected by the PKG and MEK blockers. Eph B4 receptor stimulation increased activation of both matrix metalloproteinase-2 and -9. The results from these studies indicate that Eph B4 stimulates migration and proliferation and may play a role in angiogenesis.
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PMID:Eph B4 receptor signaling mediates endothelial cell migration and proliferation via the phosphatidylinositol 3-kinase pathway. 1223 51

Emerging data suggest that matrix metalloproteinase-9 (MMP-9) plays a critical role in the pathophysiology of brain injury. However, the regulatory mechanisms involved in vivo remain unclear. In this study, we focus on a mitogen activated protein kinase (MAPK) pathway that may trigger MMP-9 after traumatic brain injury. We aim to show that inhibition of the extracellular signal regulated kinase (ERK) would attenuate MMP-9 levels, reduce blood-brain barrier damage, and attenuate edema after trauma induced by controlled cortical impact in mouse brain. Western blots showed that phospho-ERK was rapidly upregulated after trauma. Treatment with U0126, which inhibits MEK, the kinase upstream of ERK, effectively prevented the activation of ERK. After trauma, gelatin zymography showed an increase in MMP-9. U0126 significantly reduced trauma-induced MMP-9 levels. Correspondingly, U0126 ameliorated the degradation of the tight junction protein ZO-1, which is an MMP-9 substrate, and significantly attenuated tissue edema. At 7 days after trauma, traumatic lesion volumes were significantly reduced by U0126 compared with saline-treated controls. These data indicate that the ERK MAPK pathway triggers the upregulation in MMP-9 after trauma, and further suggest that targeting the upstream signaling mechanisms that regulate deleterious MMP-9 activity may reveal new therapeutic opportunities for traumatic brain injury.
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PMID:Downregulation of matrix metalloproteinase-9 and attenuation of edema via inhibition of ERK mitogen activated protein kinase in traumatic brain injury. 1249 6


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