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:2.7.10.1 (ERK)
95,504 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The urokinase-type plasminogen activator receptor (u-PAR) has been implicated in tumor progression, and previous studies have shown that the expression of this gene is strongly up-regulated by PMA. Although the signaling mechanism by which PMA modulates u-PAR expression is not known, the effect of this phorbol ester on the expression of other genes has been ascribed to activation of the c-Raf-1-ERK signaling pathway. However, in the current study we examined an alternate possibility that the inductive effect of PMA on u-PAR expression also required a JNK1-dependent signaling cascade usually associated with stress-inducing stimuli. PMA treatment of the u-PAR-deficient OVCAR-3 ovarian cancer cells, which contain low JNK activities, resulted in a rapid (5 min) increase in JNK activity. Maximal JNK activity (12-fold induction) occurred after 30 min; this preceding the earliest detected rise in u-PAR protein (2 h). Dose-response studies with PMA also indicated that the increased JNK activity was tightly correlated with elevated u-PAR protein levels. The stimulation of u-PAR promoter activity by PMA required an intact upstream AP-1 motif (-184) and in PMA-treated cells this motif was bound with c-Jun as indicated from mobility shift assays. PMA up-regulated the c-Jun trans acting activity as indicated by the higher activity of a GAL4-regulated luciferase reporter in phorbol-ester-treated cells co-transfected with an expression vector encoding the c-Jun transactivation domain fused to the GAL4 DNA-binding domain. The ability of PMA to stimulate u-PAR promoter activity was effectively titrated out by the co-expression of either a kinase-defective JNK1 or a dominant negative MEKK1 the latter being an upstream activator of JNK1. Conversely, u-PAR promoter activity was stimulated by the co-expression of a constitutively active MEKK1 and this induction was antagonized by the inclusion of the kinase-defective JNK1 plasmid. We also determined the biological significance of the JNK1-dependent signaling cascade in regulating u-PAR promoter activity by c-Ha-ras since this oncogene is activated and/or overexpressed in a variety of tumors including ovarian cancer. Transfection of an activated c-Ha-ras into OVCAR-3 cells stimulated u-PAR promoter activity over 20-fold and this could be countered by the individual expression of dominant negative expression constructs to Rac-1, MEKK1 or JNK1. Taken together, these data suggest that the PMA- or c-Ha-Ras-dependent stimulation of u-PAR gene expression requires a JNK1-dependent signaling module and that, at least for PMA, the concurrent stimulation of a JNK1-independent signaling module is also required. Thus, caution should be exercised in invoking linear signaling modules to account for the regulation of inducible gene expression.
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PMID:Stimulation of urokinase-type plasminogen activator receptor expression by PMA requires JNK1-dependent and -independent signaling modules. 967 6

The two MAP kinases JNK and ERK direct distinct cellular activities even though they share a number of common substrates, including several transcription factors. Here we have compared JNK and ERK signalling during PC12 cell differentiation and investigated how activation of c-Jun by the MAPKs contributes to this cellular response. Exposure to nerve growth factor, or expression of constitutively active MEK1-two treatments which cause differentiation of PC12 cells into a neuronal phenotype-result in activation of ERK-type MAP kinases and phosphorylation of c-Jun on several sites including Ser63 and Ser73. Constitutively activated c-Jun, which mimics the MAPK-phosphorylated form of the protein, can induce neuronal differentiation of PC12 cells independently of upstream signals. Conversely, expression of dominant-negative c-JunbZIP prevents neurite outgrowth induced by activated MEK1. Activation of MEKK1, which stimulates the JNK pathway, is not sufficient for PC12 cell differentiation but can induce apoptosis. However, neurite outgrowth is triggered when c-Jun is co-expressed with activated MEKK1 or SEK1. Consistently, MEK-induced ERK activation in PC12 cells induces c-Jun expression, while JNK signalling does not. Therefore, dual input of expression and phosphorylation of c-Jun provided by the ERK pathway is required to direct neuronal differentiation in PC12 cells.
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PMID:Differential regulation of c-Jun by ERK and JNK during PC12 cell differentiation. 968 8

Cloning and characterization of MEKK1 in 1993 revealed that in addition to Raf there were other pathways activated by extracellular stimuli that were responsible for ERK activation. Since then, three additional MEKK family members have been cloned adding even further diversity to the regulation of MAPK pathways. The MEKK family members are regulated by a diverse array of extracellular stimuli ranging from growth factors to DNA damaging stimuli and so are important for the cell to sense exposure to various environmental stimuli. One important aspect of MEKK biology is that they can potentially serve in more than one pathway. Regulation of MEKK family members often involves LMWG proteins, phosphorylation and subcellular localization. With regard to at least MEKK1, serine/threonine kinases such as NIK, GLK and HPK1 appear also to be important for regulation. Of the MEKK family members, the biological role of MEKK1 is best characterized and studies have shown that MEKK1 is important in mediating survival vs. apoptosis, possibly via its ability to regulate transcription factors, the expression of death receptors and their ligands. The biological roles of MEKK2, 3 and 4 are under investigation and undoubtedly homologous deletion of these MEKK family members will be invaluable at determining the biological functions of these MEKKs. At present, the MEKK family members are characterized as localized sensors that control cell responses at the level of gene expression, metabolism and the cytoskeleton
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PMID:The TAO of MEKK. 982 Jul 41

Protein kinase C (PKC) is a multigene family of enzymes consisting of at least 11 isoforms. It has been implicated in the induction of c-fos and other immediate response genes by various mitogens. The serum response element (SRE) in the c-fos promoter is necessary and sufficient for induction of transcription of c-fos by serum, growth factors, and the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA). It forms a complex with the ternary complex factor (TCF) and with a dimer of the serum response factor (SRF). TCF is the target of several signal transduction pathways and SRF is the target of the rhoA pathway. In this study we generated dominant-negative and constitutively active mutants of PKC-alpha, PKC-delta, PKC-epsilon, and PKC-zeta to determine the roles of individual isoforms of PKC in activation of the SRE. Transient-transfection assays with NIH 3T3 cells, using an SRE-driven luciferase reporter plasmid, indicated that PKC-alpha and PKC-epsilon, but not PKC-delta or PKC-zeta, mediate SRE activation. TPA-induced activation of the SRE was partially inhibited by dominant negative c-Raf, ERK1, or ERK2, and constitutively active mutants of PKC-alpha and PKC-epsilon activated the transactivation domain of Elk-1. TPA-induced activation of the SRE was also partially inhibited by a dominant-negative MEKK1. Furthermore, TPA treatment of serum-starved NIH 3T3 cells led to phosphorylation of SEK1, and constitutively active mutants of PKC-alpha and PKC-epsilon activated the transactivation domain of c-Jun, a major substrate of JNK. Constitutively active mutants of PKC-alpha and PKC-epsilon could also induce a mutant c-fos promoter which lacks the TCF binding site, and they also induce transactivation activity of the SRF. Furthermore, rhoA-mediated SRE activation was blocked by dominant negative mutants of PKC-alpha or PKC-epsilon. Taken together, these findings indicate that PKC-alpha and PKC-epsilon can enhance the activities of at least three signaling pathways that converge on the SRE: c-Raf-MEK1-ERK-TCF, MEKK1-SEK1-JNK-TCF, and rhoA-SRF. Thus, specific isoforms of PKC may play a role in integrating networks of signal transduction pathways that control gene expression.
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PMID:Novel roles of specific isoforms of protein kinase C in activation of the c-fos serum response element. 989 Oct 65

Raf-1 activation and Bcl-2 hyperphosphorylation following treatment with paclitaxel (Taxol) or other microtubule-active drugs is associated with mitotic arrest. Here we show that microtubule-active drugs do not activate the mitogen-activated protein kinase (MAPK) pathway in leukemia cells. PD98059, a MEK inhibitor, and SB202190, a p38 MAP kinase inhibitor, do not abrogate Bcl-2 phosphorylation nor apoptosis. Simultaneously with PARP cleavage, paclitaxel induces cleavage of Bcl-2 protein yielding a potentially pro-apoptotic 22 kDa product. In comparison, the stimulation of Raf-1 by phorbol ester (TPA) activates the MAPK pathway, causes MAPK-dependent p21WAF1/CIP1 induction, Rb dephosphorylation and growth arrest without Bcl-2 phosphorylation or apoptosis. Like TPA, cAMP induces p21WAF1/CIP1 but does not cause Bcl-2 phosphorylation. MEKK1 and Ras, upstream activators of JNK and ERK MAPK, also fail to induce Bcl-2 hyperphosphorylation. Although Lck tyrosine kinase has been recently implicated in Raf-1 activation during mitotic arrest, microtubule-active drugs induce Raf-1/Bcl-2 hyperphosphorylation and apoptosis in a Lck-deficient Jurkat cells. Therefore, microtubule-active drugs induce apoptosis which is associated with Raf-1 and Bcl-2 phosphorylation and Bcl-2 cleavage but is independent of the MAPK pathway. In contrast, TPA-activated MAPK pathway causes p21WAF1/CIP1-dependent growth arrest without apoptosis.
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PMID:Mitogen-activated protein kinase pathway is dispensable for microtubule-active drug-induced Raf-1/Bcl-2 phosphorylation and apoptosis in leukemia cells. 1040 Apr 18

We have identified a novel Jun N-terminal kinase (JNK)-binding protein, termed JNKBP1, and examined its binding affinity for JNK1, JNK2, JNK3, and extracellular signal-regulated kinase 2 (ERK2) in COS-7 cells. JNKBP1 preferentially interacted with the JNKs, but not with ERK2. Furthermore, we investigated the effect of overexpressing JNKBP1 on the JNK and ERK signaling pathways in COS-7 cells. JNKBP1 alone had only a marginal effect on JNK activity. However, the activation of JNK by MEK kinase 1 and TGF-beta-activated kinase 1 was significantly enhanced in the presence of JNKBP1. In contrast, JNKBP1 had no or very little effect on the ERK signaling pathway. These results suggest that JNKBP1 functions to facilitate the specific and efficient activation of the JNK signaling pathways.
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PMID:A novel Jun N-terminal kinase (JNK)-binding protein that enhances the activation of JNK by MEK kinase 1 and TGF-beta-activated kinase 1. 1047 13

Matrix metalloproteinase-1 (MMP-1) plays an important role in the degradation of extracellular matrix components under several physiological and pathological conditions. The expression of this protease is upregulated by mitogenic growth factors and proinflammatory cytokines, which have been shown to activate different sets of mitogen-activated protein (MAP) kinase pathways. Here we provide evidence that activation of the extracellular signal-regulated kinase 1/2 (ERK1/2) or the p38 MAP kinase pathway is sufficient to induce transcription from the MMP-1 promoter in human primary fibroblasts, whereas modulation of mRNA stability seems to be of minor importance. Upregulation of MMP-1 expression by mitogenic or inflammatory stimuli is blocked by specific small molecular weight inhibitors of the ERK pathway or the p38 pathway, respectively, and constitutively active kinases within the ERK1/2 pathway (MEKK1, MEK1) or the p38 pathway (ASK1, MEKK1, MKK3) are potent activators of the MMP-1 promoter. The current study provides evidence that distinct extracellular signals leading to upregulation of MMP-1 expression in fibroblasts are relayed independently through different MAP kinase pathways and are integrated at the level of the promoter.
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PMID:Independent role of p38 and ERK1/2 mitogen-activated kinases in the upregulation of matrix metalloproteinase-1. 1091 95

Sulindac sulfone (Exisulind) induces apoptosis and exhibits cancer chemopreventive activity, but in contrast to sulindac, it does not inhibit cyclooxygenases 1 or 2. We found that sulindac sulfone and two potent derivatives, CP248 and CP461, inhibited the cyclic GMP (cGMP) phosphodiesterases (PDE) 2 and 5 in human colon cells, and these compounds caused rapid and sustained activation of the c-Jun NH2-terminal kinase 1 (JNK1). Rapid activation of stress-activated protein/ERK kinase 1 (SEK1) and mitogen-activated protein kinase kinase kinase (MEKK1), which are upstream of JNK1, was also observed. Other compounds that increase cellular levels of cGMP also activated JNK1, and an inhibitor of protein kinase G (PKG), Rp-8-pCPT-cGMPS, inhibited JNK1 activation by the sulindac sulfone derivatives. Expression of a dominant-negative JNK1 protein inhibited CP248-induced cleavage of poly(ADP-ribose) polymerase, a marker of apoptosis. Thus, it appears that sulindac sulfone and related compounds induce apoptosis, at least in part, through activation of PKG, which then activates the MEKK1-SEK1-JNK1 cascade. These studies also indicate a role for cGMP and PKG in the JNK pathway.
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PMID:Cyclic GMP mediates apoptosis induced by sulindac derivatives via activation of c-Jun NH2-terminal kinase 1. 1105 Dec 67

Melanoma growth stimulatory activity/growth-regulated protein (MGSA/GRO), a CXC chemokine, plays an important role in inflammation, wound healing, growth regulation, angiogenesis, and tumorigenesis. Constitutive expression of MGSA/GROalpha in melanoma tumors is associated with constitutive nuclear factor (NF)-kappaB activity. We show here that either exogenous addition or continuous expression of MGSA/GROalpha in immortalized melanocytes enhances NF-kappaB activation, as well as mitogen-activated protein (MAP) kinase kinase kinase (MEKK) 1, MAP kinase kinase (MEK) 3/6, and p38 MAP kinase activation. Expression of dominant negative M-Ras (S27N), dominant negative MEKK1 (K432M), or specific chemical inhibitors for p38 MAP kinase (SB202190 and SB203580) block MGSA/GROalpha-induced NF-kappaB transactivation, demonstrating that Ras, MEKK1, and p38 are involved in the signal pathways of MGSA/GROalpha activation of NF-kappaB. Expression of dominant active Ras or dominant active MEKK1 alone can also stimulate NF-kappaB activation. The expression of dominant negative MEKK1 inhibits the Ras-induced NF-kappaB activation, suggesting that MEKK1 is a downstream target of Ras. Moreover, MGSA/GROalpha induction of NF-kappaB is independent of the MEK1/ERK cascade, because MGSA/GROalpha failed to increase ERK and ELK activation, and specific chemical inhibitors for MEK1 (PD98059) had no effect on MGSA/GROalpha-enhanced NF-kappaB activation. These data demonstrate that NF-kappaB activation is required for MGSA/GROalpha-induced melanocyte transformation through a Ras/MEKK1/p38 cascade in melanocytes.
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PMID:Nuclear factor-kappa B activation by the CXC chemokine melanoma growth-stimulatory activity/growth-regulated protein involves the MEKK1/p38 mitogen-activated protein kinase pathway. 1106 39

Receptor activator of nuclear factor kappaB (RANK), a lately identified member of the tumor necrosis factor receptor superfamily, plays important roles both in osteoclastogenesis and in lymph node development. Previously, we and others showed that RANK could stimulate the activity of c-Jun N-terminal kinase (JNK). In this study, we investigated the mechanism by which RANK activates JNK. We found that N-terminal deletion mutants of tumor necrosis factor receptor-associated factor 2 and 6 were inhibitory to RANK activation of JNK. The JNK activation by RANK was also reduced by cotransfection of kinase-inactive mutants of apoptosis signal-regulating kinase 1, MAPK/ERK kinase kinase 1, and nuclear factor kappaB-inducing kinase. In addition, dominant negative mutants of Rac and Ras decreased the RANK stimulation of JNK activity. Furthermore, we determined whether the RANK engagement of JNK signaling pathways could lead to the activation of the activator protein 1 (AP-1) transcription factor, one of the potential downstream targets of activated JNK. RANK was found to activate AP-1 in a manner dependent on the signaling molecules involved in the JNK activation by this receptor. Furthermore, the activation of JNK and ERK, but not that of p38, appeared to be involved in the AP-1 activation by RANK. Thus, RANK may use both JNK and ERK pathways to signal to the AP-1 transcription factor.
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PMID:Activation of c-Jun N-terminal kinase and activator protein 1 by receptor activator of nuclear factor kappaB. 1109 94


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