Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.24 (mitogen-activated protein kinase)
 95,810 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The expression of the urokinase-type plasminogen activator, which plays a crucial role in tissue remodeling by controlling the synthesis of the broadly acting plasmin serine protease, is regulated by several tyrosine kinases. Since the actions of these tyrosine kinases is dependent on the activation of ras proteins, we undertook a study to identify signaling events downstream of ras responsible for the stimulation of urokinase promoter activity. Transient expression of an activated c-Ha-ras in OVCAR-3 cells, which do not harbor the mutated oncogene, led to a dose-dependent trans-activation of the urokinase promoter. A sequence residing between -2109 and -1964 was critical for the stimulation of the urokinase promoter by c-Ha-ras. Mutation of an AP-1 and a PEA3 site at -1967 and -1973, respectively, or the co-expression of a transactivation domain-lacking c-jun substantially impaired the ability of c-Ha-ras to stimulate urokinase promoter activity. The induction of the urokinase promoter by ras was completely blocked by expression of a dominant negative c-raf expression vector and substantially reduced in cells made to co-express a catalytically inactive mitogen-activated protein kinase kinase. Further, the expression of an ERK1/ERK2-inactivating phosphatase (CL100) abrogated the stimulation of the urokinase promoter by c-Ha-ras. These data argue for a role of a mitogen-activated protein kinase-dependent signaling pathway in the regulation of urokinase promoter activity by ras.
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PMID:Involvement of a mitogen-activated protein kinase signaling pathway in the regulation of urokinase promoter activity by c-Ha-ras. 755 39

Fibroblast growth factors (FGFs) play a role in biological processes such as cell growth and development, angiogenesis, and wound healing. Several genes have been shown to be induced by FGFs, but the underlying mechanisms have not been elucidated. We investigated the effect of FGF-2 (basic FGF) on the urokinase-type plasminogen activator (uPA) gene in NIH 3T3 fibroblasts. We found that the uPA gene is transcriptionally induced by FGF-2 as well as by 12-O-tetradecanoylphorbol-13 -acetate involving a PEA3/AP1 element located 2.4 kb upstream of the transcription initiation site; neither induction requires ongoing protein synthesis. Unlike 12-O-tetradecanoylphorbol-13-acetate induction, FGF-2 induction was not impaired by protein kinase C down-regulation. Analyses of various signaling molecules by Western blotting, extracellular signal-regulated kinase (ERK) activity assays, and transient transfection assays (cotransfection of a uPA-reporter gene construct with expression vectors for wild-type or dominant negative type of these molecules or for ERK-specific protein phosphatase MKP-1) showed that a Ras/Raf-1/MEK/ERK-2/JunD pathway is induced by FGF-2 and 12-O-tetradecanoylphorbol-13-acetate, leading to the activation of the uPA gene.
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PMID:Elucidation of a signaling pathway induced by FGF-2 leading to uPA gene expression in NIH 3T3 fibroblasts. 854 15

The urokinase-type plasminogen activator contributes to tissue remodeling by controlling the synthesis of the extracellular matrix-degrading plasmin. We undertook a study to determine the role of the extracellular signal-regulated kinases (ERKs) in the regulation of urokinase-type plasminogen activator expression in a squamous cell carcinoma cell line (UM-SCC-1) that contains a transcriptionally activated urokinase-type plasminogen activator gene. Transient transfection studies using a CAT reporter driven by the urokinase-type plasminogen activator promoter, which had progressive 5' deletions or which had been point-mutated, indicated the requirement of binding sites for AP-1 (-1967) and PEA3 (-1973) for its maximal activation. Expression of a mutant jun protein, which lacks the transactivation domain, caused a dose-dependent repression of a CAT reporter driven by either the urokinase-type plasminogen activator promoter or three tandem AP-1 repeats upstream of a thymidine kinase minimal promoter indicating the importance of AP-1-binding transcription factor(s) in the regulation of urokinase-type plasminogen activator synthesis. Mobility shift assays with UM-SCC-1 nuclear extract revealed binding of fos and junD proteins to an oligonucleotide spanning the AP-1 site at -1967. In-gel kinase assays indicated the constitutive activation of ERK1, which regulates fos synthesis via phosphorylation of p62TCF, but not ERK2, in UM-SCC-1 cells. Moreover, the expression of a dominant-negative ERK1, but not ERK2, repressed urokinase-type plasminogen activator promoter activity. Similarly, interfering with the function of the c-raf serine-threonine kinase, which lies upstream of ERK1, by the expression of a kinase-inactive c-raf repressed the activity of a CAT reporter driven by either the urokinase-type plasminogen activator promotor or tandem AP-1 repeats. These data suggest that urokinase-type plasminogen activator expression in UM-SCC-1 cells is regulated partly by an ERK1, but not ERK2, -dependent signaling pathway.
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PMID:Regulation of urokinase-type plasminogen activator expression by an ERK1-dependent signaling pathway in a squamous cell carcinoma cell line. 876 47

PEA3, a member of the Ets family of transcriptional regulatory proteins, binds to the PEA3 promoter element and stimulates transcription through this site. The activity of the PEA3 element is regulated by mitogens, activated receptor tyrosine kinases, and oncogenic members of the Ras signal transduction pathway. However, it is not clear whether PEA3 mediates transcriptional regulation by these agents because a number of different Ets proteins can functionally interact with the PEA3 element. To specifically learn whether the activity of PEA3 is regulated, we investigated the ability of constitutively-activated Ras (Ha-RasV12) and signaling proteins downstream of Ras to alter PEA3-dependent reporter gene expression in COS cells. Ha-RasV12 and activated proteins in both the extra-cellular regulated kinase (ERK) and the stress-activated protein kinase (SAPK) or Jun N-terminal kinase (JNK) cascades independently stimulated PEA3-mediated gene expression. Ha-RasV12 stimulation of PEA3 activity was reduced by dominant-negative mutants in each of these protein kinase cascades, suggesting that Ras activates PEA3 through both pathways. Furthermore, the ability of unique activators of each kinase cascade to stimulate PEA3-dependent gene expression was selectively reduced by dominant-negative mutants within the homologous but not the heterologous pathway. Hence two distinct mitogen-activated protein kinase (MAPK) cascades regulate PEA3 activity. PEA3 was phosphorylated in vivo at serine residues consistent with the possibility that it may be a direct target of MAPKs.
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PMID:The activity of the Ets transcription factor PEA3 is regulated by two distinct MAPK cascades. 880 7

Recent studies support a model for signal transduction from activated receptor tyrosine kinases to Ras which, in turn, activates the pathway of the mitogen-activated protein kinase (MAPK). Although some members of the Ets transcription factor family have been shown to be activated by this signaling pathway, no data are available on the activation of the PEA3 group of Ets proteins. This group is composed of three members -- PEA3, ER81 and ERM -- which are very similar in the DNA-binding domain, the ETS domain, in the 32 residue amino-terminal acidic domain and in the 61 residue carboxy-terminal domain. First of all we demonstrated that ERM-transfected cells contain a positive labeling in the nucleus, and we concluded that a nuclear localization signal might be situated in the ETS domain. We then showed that of four putative reporter plasmids, ERM activated the artificial 3 x TORU plasmid which contains an Ets binding site contiguous to an AP1 one. This transactivation enhancement requires the presence of the ERM amino-terminal domain. In contrast, although the lack of the carboxy-terminal domain induced a decrease in transactivation, this latter domain is not crucial. By using the E74-reporter plasmid system which is not basically activated by ERM, we showed that the activation of the Ras/Raf-1/MAPK pathway significantly enhanced ERM-mediated transactivation. The deletion of the amino-terminal transactivation domain abolished the capacity of stimulated MAPK to activate ERM. We also demonstrated that ERM can also be activated through the protein kinase A (PKA), another signaling pathway. Nevertheless, the MAPK and PKA activation of ERM are not synergistic. Finally, we showed that this Ets transcription factor is in vitro phosphorylated by both activated ERK-2 and activated PKA. ERM has thus been identified as a transcription factor which is a target for two different signaling pathways and might therefore be involved in the mitogenic response of cells.
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PMID:The ETS-related transcription factor ERM is a nuclear target of signaling cascades involving MAPK and PKA. 889 21

The broad spectrum protease urokinase-type plasminogen activator (uPA) has been implicated in muscle regeneration in vivo as well as in myogenic proliferation and differentiation in vitro. These processes are known to be modulated by basic fibroblast growth factor (FGF-2) and serum. We therefore investigated the mechanism(s) underlying the regulation of uPA expression by these two stimuli in proliferating and differentiating myoblasts. The expression of uPA mRNA and the activity of the uPA gene product were induced by FGF-2 and serum in proliferating myoblasts. uPA induction occurred at the level of transcription and required the uPA-PEA3/AP1 enhancer element, since deletion of this site in the full promoter abrogated induction by FGF-2 and serum. Using L6E9 skeletal myoblasts, devoid of endogenous FGF receptors, which have been engineered to express either FGF receptor-1 (FGFR1) or FGF receptor-4 (FGFR4), we have demonstrated that both receptors, known to be expressed in skeletal muscle cell precursors, were able to mediate uPA induction by FGF-2, whereas serum stimulation was FGF receptor-independent. The induction of uPA by FGF-2 and serum in FGFR1- and in FGFR4-expressing myoblasts required the mitogen-activated protein kinase pathway, since treatment of cells with a specific inhibitor of the mitogen-activated protein kinase/extracellular signal-regulated kinase-2 kinase, PD98059, blocked uPA promoter induction. Although FGF-2 and serum induced uPA in proliferating myoblasts, their actions on cell-cell contact-induced differentiating myoblasts differed dramatically. FGF-2, but not serum, repressed uPA expression in differentiation-committed myoblasts, and these effects were also shown to occur at the level of uPA transcription. Altogether, these results indicate a dual regulation of the uPA gene by FGF-2 and serum, which ensures uPA expression throughout the whole myogenic process in different myoblastic lineages. The effects of FGF-2 and serum on uPA expression may contribute to the proteolytic activity required during myoblast migration and fusion, as well as in muscle regeneration.
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PMID:Differential regulation of urokinase-type plasminogen activator expression by basic fibroblast growth factor and serum in myogenesis. Requirement of a common mitogen-activated protein kinase pathway. 944 43

The HER2/neu gene, which is overexpressed in 20-30% of human breast tumors, encodes a receptor tyrosine kinase that functions through multiple signaling pathways to regulate the activity of nuclear transcription factors. We have reported that PEA3, an Ets family transcription factor, is overexpressed in HER2/Neu-induced breast tumors and their metastases. To account for the increased levels of PEA3 in these tumors we have suggested that HER2/Neu enhances PEA3 transcriptional activity, which then acts to stimulate expression of the PEA3 gene. This hypothesis is consistent with the occurrence of PEA3 binding sites in the PEA3 promoter and with the ability of PEA3 to transactivate this promoter. To learn whether HER2/Neu indeed regulates PEA3 activity we measured the capacity of constitutively-activated HER2/Neu to affect PEA3-dependent reporter gene expression. Coexpression of PEA3 and HER2/Neu stimulated PEA3-dependent reporter gene expression to a much greater extent than did either protein alone suggesting that HER2/Neu upregulates the transcriptional activity of PEA3. To define the pathway whereby HER2/Neu functions we employed dominant-negative mutants of signaling proteins known to be downstream of HER2/Neu. Overexpression of Rap1a, a Ras-related protein capable of antagonizing Ras function, completely inhibited the ability of HER2/Neu to stimulate PEA3-dependent gene expression. Ras is known to stimulate at least two mitogen-activated protein kinase (MAPK) cascades, the extracellular-regulated kinase (ERK) cascade and the stress-activated kinase (SAPK) or Jun kinase (JNK) cascade. Similarly, HER2/Neu activated both ERKs and SAPKs/JNKs in a Ras-dependent fashion. Dominant-inhibitory mutants in either the ERK or SAPK/JNK cascades partially inhibited HER2/Neu activation of PEA3-dependent gene expression. These findings suggest that HER2/Neu regulates PEA3 activity through two different Ras-dependent MAPK pathways.
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PMID:The PEA3 Ets transcription factor is a downstream target of the HER2/Neu receptor tyrosine kinase. 946 55

The PEA3 subfamily of ETS-domain proteins play important roles in regulating transcriptional activation and have been implicated in several tumorigenic processes. Here we describe the identification of a further member of this family from zebrafish which most likely represents a homologue of PEA3. A high degree of sequence conservation is observed in the ETS DNA-binding domain and acidic transcriptional activation domain. The DNA binding specificity of zebrafish PEA3 is virtually identical to that exhibited by mammalian family members and is autoregulated by cisacting inhibitory domains. Transcriptional activation by zebrafish PEA3 is potentiated by the ERK MAP kinase and protein kinase A pathways. During embryogenesis, PEA3 is expressed in complex spatial and temporal patterns in both mesodermal somites and ectodermal tissues including the brain, dorsal spinal chord and neural crest. Our characterisation of zebrafish PEA3 furthers our understanding of its molecular function and its expression profile suggests a novel role in cell patterning in the early vertebrate embryo.
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PMID:Molecular characterization of the zebrafish PEA3 ETS-domain transcription factor. 967 18

Hepatocyte growth factor/scatter factor (HGF/SF) is a pleiotropic effector inducing invasion and metastasis of tumor cells that express the Met tyrosine kinase receptor. One of the effectors of HGF/SF is the urokinase-type plasminogen activator, a serine protease that facilitates tumor progression and metastasis by controlling the synthesis of the extracellular matrix degrading plasmin. Stimulation of NIH 3T3 cells that were stably transfected with the human Met receptor (NIH 3T3-Methum) with HGF/SF induced a trans-activation of the urokinase promoter and urokinase secretion. Induction of the urokinase promoter by HGF/SF via the Met receptor was blocked by co-expression of a dominant-negative Grb2 and Sos1 expression construct. Further, the expression of the catalytically inactive mutants of Ha-Ras, RhoA, c-Raf, and Erk2 or addition of the Mek1-specific inhibitor PD 098059 abrogated the stimulation of the urokinase promoter by HGF/SF. A sequence residing between -2109 and -1870 base pairs (bp) was critical for stimulation of the urokinase gene by HGF/SF. Mobility shift assays with oligonucleotides spanning an AP-1 site at -1880 bp or a combined PEA3/AP-1 site at -1967 bp showed binding of nuclear factors from NIH 3T3-Methum cells. Expression of an expression plasmid that inhibits DNA binding of AP-1 proteins (A-Fos) abrogated inducible and basal activation of the urokinase promoter. Nuclear extract from unstimulated NIH 3T3-Methum cells contained more JunD and showed a stronger JunD supershift with the AP-1 oligonucleotides, compared with HGF/SF-stimulated cells. Consistent with the levels of JunD expression being functionally important for basal expression of the urokinase promoter, we found that overexpression of wild type JunD inhibited the induction of the urokinase promoter by HGF/SF. These data suggest that the induction of urokinase by HGF/SF is regulated by a Grb2/Sos1/Ha-Ras/c-Raf/RhoA/Mek1/Erk2/c-++ +Jun-dependent mitogen-activated protein kinase pathway.
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PMID:Activation mechanisms of the urokinase-type plasminogen activator promoter by hepatocyte growth factor/scatter factor. 1034 97

Transformation of normal cloned rat embryo fibroblast (CREF) cells with cellular oncogenes results in acquisition of anchorage-independent growth and oncogenic potential in nude mice. These cellular changes correlate with an induction in the expression of a cancer progression-promoting gene, progression elevated gene-3 (PEG-3). To define the mechanism of activation of PEG-3 as a function of transformation by the Ha-ras and v-raf oncogenes, evaluations of the signaling and transcriptional regulation of the approximately 2.0 kb promoter region of the PEG-3 gene, PEG-Prom, was undertaken. The full-length and various mutated regions of the PEG-Prom were linked to a luciferase reporter construct and tested for promoter activity in CREF and oncogene-transformed CREF cells. An analysis was also performed using CREF cells doubly transformed with Ha-ras and the Ha-ras specific suppressor gene Krev-1, which inhibits the transformed phenotype in vitro. These assays document an association between expression of the transcription regulator PEA3 and PEG-3. The levels of PEA3 and PEG-3 RNA and proteins are elevated in the oncogenically transformed CREF cells, and reduced in transformation and tumorigenic suppressed Ha-ras/Krev-1 doubly transformed CREF cells. Enhanced tumorigenic behavior, PEG-3 promoter function and PEG-3 expression in Ha-ras transformed cells were all dependent upon increased activity within the mitogen-activated protein kinase (MAPK) pathway. Electrophoretic mobility shift assays and DNase I footprinting experiments indicate that PEA3 binds to sites within the PEG-Prom in transformed rodent cells in an area adjacent to the TATA box in a MAPK-dependent fashion. These findings demonstrate an association between Ha-ras and v-raf transformation of CREF cells with elevated PEA3 and PEG-3 expression, and they implicate MAPK signaling via PEA3 as a signaling cascade involved in activation of the PEG-Prom.
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PMID:PEA3 sites within the progression elevated gene-3 (PEG-3) promoter and mitogen-activated protein kinase contribute to differential PEG-3 expression in Ha-ras and v-raf oncogene transformed rat embryo cells. 1129 38


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