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)

The 92 kDa type IV collagenase (MMP-9), which degrades type IV collagen, has been implicated in tissue remodeling. The purpose of the current study was to determine the role of Jun amino-terminal kinase (JNK)- and extracellular signal-regulated kinase- (ERK)-dependent signaling cascades in the regulation of MMP-9 expression. Towards this end, we first determined the transcriptional requirements for MMP-9 promoter activity in a cell line (UM-SCC-1) which is an avid secretor of this collagenase. Transfection of these cells with a CAT reporter driven by progressive 5' deleted fragments of the MMP-9 promoter indicated the requirement of a region spanning -144 to -73 for optimal promoter activity. DNase I footprinting revealed a protected region of the promoter spanning nucleotides -91 to -68 and containing a consensus AP-1 motif at -79. Mutation of this AP-1 motif practically abolished the activity of the MMP-9 promoter-driven CAT reporter. Mobility shift assays indicated c-Fos and Jun-D bound to this motif and transfection of the cells with a mutated c-Jun, which quenches the function of endogenous Jun and Fos proteins, decreased MMP-9 promoter activity by 80%. UM-SCC-1 cells contained a constitutively activated JNK and the expression of a kinase-deficient JNK1 reduced the activity of a CAT reporter driven either by the MMP-9 promoter or by three tandem AP-1 repeats upstream of a thymidine kinase minimal promoter. Conditioned medium collected from UM-SCC-1 cells transfected with the dominant negative JNK1 expression vector diminished 92 kDa gelatinolysis. Similarly, interfering with MEKK, which lies upstream of JNK1, using a dominant negative expression vector reduced MMP-9 promoter activity over the same concentration range which repressed the AP-1-thymidine kinase CAT reporter construct. UM-SCC-1 cells also contained a constitutively activated ERK1. MMP-9 expression, as determined by CAT assays and by zymography, was reduced by the co-expression of a kinase-deficient ERK1. Interfering with MEK1, which is an upstream activator of ERK1, either with PD 098059, which prevents the activation of MEK1, or with a dominant negative expression construct, reduced 92 kDa gelatinolysis and MMP-9 promoter activity respectively. c-Raf-1 is an upstream activator of MEK1 and a kinase-deficient c-Raf-1 expression construct decreased the activity of a promoter driven by either the MMP-9 promoter or three tandem AP-1 repeats. Conversely, treatment of UM-SCC-1 cells with PMA, which activates c-Raf-1, increased 92 kDa gelatinolysis. These data suggest that MMP-9 expression in UM-SCC-1 cells, is regulated by JNK- and ERK-dependent signaling pathways.
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PMID:Regulation of 92 kDa type IV collagenase expression by the jun aminoterminal kinase- and the extracellular signal-regulated kinase-dependent signaling cascades. 913 92

Activation of the extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase (MAPK) pathway is required for ligand-dependent regulation of numerous cellular functions by receptor tyrosine kinases. We have shown previously that although many receptor tyrosine kinase ligands are mitogens for keratinocytes, cell migration and induction of the 92-kilodalton gelatinase/matrix metalloproteinase (MMP)-9 are selectively regulated by the epidermal growth factor and scatter factor/hepatocyte growth factor receptors. In this report we present evidence of an underlying mechanism to account for these observed differences in receptor tyrosine kinase-mediated response. Ligands that are mitogenic, but do not induce MMP-9 or colony dispersion, transiently activate the p42/p44 ERK/MAP kinases. In contrast, ligands that stimulate MMP-9 induction and colony dispersion induced sustained activation of these kinases. The functional significance of sustained MAPK activation was demonstrated by inhibition of the MAP kinase kinase MEK1. Disruption of the prolonged signal by addition of the MEK1 inhibitor PD 98059 up to 4 h after growth factor stimulation substantially impaired ligand-dependent colony dispersion and MMP-9 induction. These findings support the conclusion that duration of MAPK activation is an important determinant for certain growth factor-mediated functions in keratinocytes.
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PMID:Sustained activation of the mitogen-activated protein kinase pathway. A mechanism underlying receptor tyrosine kinase specificity for matrix metalloproteinase-9 induction and cell migration. 993 37

Mitogen-activated protein kinases (MAPKs) play a major role in the mitogenic signal transduction pathway and are essential components of both growth and differentiation. Constitutive activation of the MAPK cascade is associated with the carcinogenesis and metastasis of human breast and renal cell carcinomas. The gelatinases B (MMP-9) and A (MMP-2) are 2 members of the matrix metalloproteinase (MMPs) family which are expressed in human cancers and thought to play a critical role in tumor cell invasion and metastasis. In a previous study, we have shown that EGF and amphiregulin upregulate MMP-9 in metastatic SKBR-3 cells but have no effect on MMP-2 secretion. We now investigated specific step(s) in EGF-induced signalling associated with regulation of cell proliferation and MMP-9 induction. EGF-induced signalling in SKBR-3 cells was blocked by relatively specific inhibitors either on ras (FPT inhibitor-1) or P13 kinase (Wortmannin) or by reduction in EGF-induced tyrosine kinase activity (RG 13022). Blocking these signalling pathways significantly inhibited of EGF-induced cell proliferation but only partially reduced in EGF-induced MMP-9 secretion. In contrast, when SKBR-3 cells were exposed to MEK inhibitor (PD 98059) or MAPK inhibitors (Apigenin or MAPK antisense phosphorothioate oligodeoxynucleotides), EGF-induced cell proliferation, MMP-9 induction and invasion through reconstituted basement membrane were significantly reduced. Our results suggest that interfering with MAPK activity may provide a novel means of controlling growth and invasiveness of tumors in which the signalling cascade is activated.
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PMID:Mitogen-activated protein kinase (MAPK) regulates the expression of progelatinase B (MMP-9) in breast epithelial cells. 1038 62

Invasion is an essential cellular response that plays an important role in a number of physiological and pathological processes. Matrix metalloproteinase (MMP) production and cell movement are diverse cellular responses integral to the process of invasion. The complexity of the invasive process suggests the necessity of coordinate activation of more than one signaling pathway in order to activate specific factors responsible for regulating these cellular responses. In this report, we demonstrate that cell movement and MMP-9 production are both directly dependent on the activation of endogenous ERK signaling in hepatocyte growth factor (HGF)-or epidermal growth factor (EGF)-stimulated human epidermal keratinocytes. The kinetic profiles of endogenous MEK and ERK activity suggest that prolonged activation of these signal transducers is an underlying mechanism involved in stimulating cell motility and MMP-9 production. In support of this finding, a transient MEK/ERK signal elicited by keratinocyte growth factor (KGF) or insulin-like growth factor-1 (IGF-1) fails to stimulate these invasion-related responses. Specific inhibition of MEK leads to suppression of ERK activation, marked reduction in steady-state levels of c-Fos, and inhibition of cell movement and MMP-9 production. This occurs despite continued activation of JNK and c-Jun signaling in the presence of MEK-specific inhibition. In contrast, when JNK activity is specifically inhibited in HGF-stimulated cells, AP-1 activity is suppressed but cell motility is not affected. This evidence suggests that while ERK and JNK activity are necessary for AP-1 activation, ERK but not JNK is sufficient in stimulating cell motility.
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PMID:Role of ERK and JNK pathways in regulating cell motility and matrix metalloproteinase 9 production in growth factor-stimulated human epidermal keratinocytes. 1039 97

T-lymphocyte migration into tissues requires focal degradation of the basement membrane. In this study, we show that transient adherence to fibronectin induces the production of activated forms of matrix metalloproteinase-2 (MMP-2) and MMP-9, as well as downregulation of tissue inhibitor of metalloproteinase-2 (TIMP-2) by T-cell lines. MMP-2 activation was likely achieved by inducing a coordinated expression of membrane-type matrix metalloproteinase-1 (MMP-14), a major activator of MMP-2. Blocking monoclonal antibodies against alpha4, alpha5, and alphav integrins strongly reduced MMP-2 and MMP-9 production induced by fibronectin. Disrupting actin cytoskeleton organization by cytochalasin D strongly enhanced fibronectin-induced MMP-2 and MMP-9 expression. Inhibiting Src tyrosine kinases with herbimycin A reduced MMP-2 and MMP-9 production with no effect on cell attachment. By contrast, G-protein inhibition by pertussis toxin, or transfection with a dominant negative mutant of Ha-Ras strongly increased fibronectin-induced MMP-2 and MMP-9. Inhibition of PI3 kinase, MAPkinase (MEK1), or p38 MAPkinase by wortmannin, PD 98059, or SB 202190, respectively, strongly promoted fibronectin-induced MMP2 and MMP-9. Cells at high density lost their ability to synthesize MMP-2 and MMP-9 in response to fibronectin and MMP expression was restored by transfection with a dominant-negative mutant of Ha-Ras or by treatment with wortmannin, PD 98059, or SB 202190. Our findings suggest that adhesion to fibronectin transduces both stimulatory (through Src-type tyrosin kinases) and inhibitory signals (through Ras/MAPKinase signaling pathways) for MMP-2 and MMP-9 expression by T lymphocytes and that their relative predominance is regulated by additional stimuli related to cell adhesion, motility, and growth.
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PMID:Fibronectin upregulates gelatinase B (MMP-9) and induces coordinated expression of gelatinase A (MMP-2) and its activator MT1-MMP (MMP-14) by human T lymphocyte cell lines. A process repressed through RAS/MAP kinase signaling pathways. 1051 79

To search for the intracellular signaling pathway critical for the secretion of matrix metalloproteinases (MMP), we studied the effects of dominant negative Ras (S17N Ras) and dominant negative MEK1 (MEK1AA) expression in v-crk-transformed 3Y1. Expression of either S17N Ras or MEK1AA dramatically suppressed the augmented secretion of MMP-2 and MMP-9 in v-crk-transfected 3Y1. Similarly, a Ras farnesyltransferase inhibitor, manumycin A, and a MEK1 inhibitor, U0126, suppressed MMP secretion in a dose-dependent manner, whereas a PI3 kinase inhibitor, wortmannin, could not. In addition, the suppression of MMP secretion by S17N Ras showed good correlation with the inhibition of in vitro invasiveness of the cells. In contrast, expression of dominant negative C3G did not suppress MMP secretion, although it substantially blocked the c-Jun N-terminal kinase activation. Taken together, the Ras-MEK1 pathway, but not the C3G-JNK pathway, seems to play a key role in the activation of MMP secretion and, hence, the invasiveness of v-crk-transformed cells.
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PMID:The Ras-mitogen-activated protein kinase pathway is critical for the activation of matrix metalloproteinase secretion and the invasiveness in v-crk-transformed 3Y1. 1081 Nov 9

Matrix metalloproteinase expression was examined in a series of mammalian cell lines of varying degrees of malignant progression. The expression of MMP-2 and MMP-9 was found to correlate with ras-mediated cellular transformation and as a function of malignant potential. Altered MMP-2 and MMP-9 expression was found to correlate also in other oncogene transformed cell lines and the level of expression of both MMP-2 and MMP-9 correlated with metastatic potential. Increased expression of both MMP-2 and MMP-9 was also found in cells which constitutively over-express MAP kinase kinase suggesting that one of the consequences of the persistent activation of the MAP kinase pathway is elevated expression of MMP-2 and MMP-9. Additionally, this study demonstrated a correlation between the expression of MMP-3 (stromelysin-1) and the level of ras expressed in cells and with the cells' ability to form tumors and with malignant potential. The existence of a novel 80 kDa caseinase activity which correlates with ras expression and the ability of the cell to form tumors was also demonstrated. The growth status of transformed cells was also found to be important in determining the expression of MMP-2 mRNA but not MMP-9 mRNA expression, and this expression was cell-type specific. This study also demonstrates that oncogenes can interact to influence and to determine the nature of the matrix metalloproteinases expressed and that this interaction results in a tumorigenic phenotype and, most importantly, contributes to the metastatic phenotype. Alterations in the expression and the regulation of MMPs, particularly MMP-2 and MMP-9, constitute an integral part of the altered growth regulatory program found within transformed cells and in particular, in transformed cells capable of malignant progression.
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PMID:Altered matrix metalloproteinase expression associated with oncogene-mediated cellular transformation and metastasis formation. 1140 28

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

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

The invasive phenotype of cancers critically depends on the expression of proteases such as the M(R) 92,000 type IV collagenase (MMP-9). Several growth factors and oncogenes were found to increase promoter activity and as a consequence protease expression. This frequently requires the activation of the transcription factor AP-1 by signal transduction cascades such as the ERK and JNK pathways. We have previously demonstrated that the tumor promoter TPA can induce MMP-9 expression via a third signaling cascade, the p38 pathway. Considering that TPA is a potent activator of AP-1, we hypothesized that this transcription factor might also be required for p38 pathway-dependent MMP-9 regulation. While dominant negative p38 and MKK-6 mutants reduced MMP-9 promoter activity in CAT assays, a construct encoding an activating mutation in the MKK-6 protein potently stimulated it. This was mediated via 144 bp of the 5'flanking region of the wild-type promoter, which contains an AP-1 site at -79. Both point mutations in this motif and the expression of a c-jun protein lacking its transactivation domain and therefore acting as a dominant negative AP-1 mutant abrogated MKK-6-dependent promoter stimulation. Finally SB 203580, a specific p38 pathway inhibitor, reduced MMP-9 expression/secretion and in vitro invasion of cancer cells. Thus, our results provide evidence that also the third SAPK/MAPK signaling cascade, the p38 signal transduction pathway, stimulates MMP-9 expression in an AP-1-dependent fashion.
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PMID:The p38 SAPK pathway regulates the expression of the MMP-9 collagenase via AP-1-dependent promoter activation. 1171 47


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