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)

Ras activates a multitude of downstream activities with roles in cellular proliferation, invasion and metastasis, differentiation, and programmed cell death. In this work we have evaluated the requirement of extracellular signal-regulated protein kinase (ERK), c-Jun NH2-terminal kinase kinase (JNKK), and c-Jun/AP-1 activities in transformation and extracellular matrix invasion of ras oncogene expressing NIH 3T3 fibroblasts by expressing stable mutant genes that constitutively inhibit these activities. Whereas the inhibition of ERK activity reverts the transformed and invasive phenotype, the inhibition of the JNK pathway and AP-1 trans-activating activities by JNKK[K129R] and c-Jun(TAM67) had no effect on the ability of the ras oncogene-expressing cells to grow in soft agar or invade Matrigel basement membrane. Thus an elevated JNK activity and/or c-Jun/AP-1 trans-activating activity are not absolute requirements for ras transformation or invasion through basement membrane, and the dependence on AP-1 activity for transformation is cell-specific. However, inhibition of JNK kinase (JNKK) in ras-transformed cells with normally elevated JNK activity switches the protease-dependent invasive phenotype from a urokinase plasminogen activator (uPA)-dependent to a cathepsin L (CL)-dependent invasive phenotype. Conversely, treatment of ras-transformed cells of low constitutive JNK activity with the JNK stimulator, anisomycin, converts the protease mRNA levels from those characteristic of a CL-dependent to a uPA-dependent phenotype. These protease phenotypes can be duplicated in untransformed NIH 3T3 cells that express platelet-derived growth factor receptors and m1 muscarinic receptors that selectively stimulate the ERK or JNK pathways, respectively. It is concluded that high ERK activity is required for both protease phenotypes, whereas the JNK pathway and c-Jun/AP-1 activity are not required for transformation but regulate a switch between uPA and CL protease phenotypes in both transformed and untransformed cells. In ras-transformed NIH 3T3 fibroblasts, the uPA- and CL-dependent protease phenotypes are redundant in their ability to invade through basement membrane.
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PMID:Role of mitogen-activated protein kinases and c-Jun/AP-1 trans-activating activity in the regulation of protease mRNAs and the malignant phenotype in NIH 3T3 fibroblasts. 987 19

Cellular growth and differentiation are controlled by multiple extracellular signals, many of which activate extracellular signal-regulated kinase (ERK)/mitogen-activated protein (MAP) kinases. Components of the MAP kinase pathways also cause oncogenic transformation in their constitutively active forms. Moreover, expression of activated ras can confer metastatic potential upon some cells. Activation of MAP kinases requires phosphorylation of both Thr and Tyr in the catalytic domain by a family of dual-specificity kinases, called MEKs (MAP kinase/ERK kinase). MEK1 is activated by phosphorylation at Ser218 and Ser222 by Raf. Mutation of these two sites to acidic residues, specifically [Asp218], [Asp218, Asp222], and [Glu218, Glu222], results in constitutively active MEK1. Using these mutant variants of MEK1, we showed previously that transfection of NIH/3T3 or Swiss 3T3 cells causes morphological transformation and increases growth on soft agar, independent of ERK activity. The transformed cell lines show increased expression of matrix metalloproteinases 2 and 9 and cathepsin L, proteinases that have been implicated in the metastatic process. We tested NIH3T3 cells transfected with the [Asp218] or [Asp218, Asp222] for metastatic potential after i.v. injection into athymic mice. Parental 3T3 cells formed no tumors grossly or histologically. However, all MEK1 mutant transformants formed macroscopic metastases. Thus, like activated Ras, MEK1 can confer both tumorigenic and metastatic potential upon NIH3T3 cells. These results refine the mechanism through which ras could confer tumorigenic and metastatic potential (ie., the critical determinants of tumorigenic and metastatic potential are downstream of MEK1).
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PMID:Transfection of constitutively active mitogen-activated protein/extracellular signal-regulated kinase kinase confers tumorigenic and metastatic potentials to NIH3T3 cells. 1074 22

The growth factor receptor-dependent protein kinase Raf-1 is activated by GTP-bound Ras, thereby activating the mitogen-activated protein kinase pathway. To study the role of Raf in transformation we transduced Rat-1 cells with a tetracycline-regulatable retroviral vector encoding the constitutively active oncogenic C-terminal fragment of the human Raf-1 protein. Using subtractive hybridization of mRNAs from induced and noninduced cells and robot-assisted screening by complex hybridization, Raf-induced genes with various different characteristics of induction were investigated. Among the strongly induced genes were those involved in carcinogenesis such as metalloproteinases 3, 10 and 13, cathepsin L, ornithine decarboxylase, and putative tumor-suppressing genes such as monocyte chemoattracting protein 1, interferon-induced protein 10, a recently identified 2'-5' oligoadenylate synthetase-like protein, and plasminogen activator inhibitor type 2. Other components of the plasminogen activator system were not induced. Plasminogen activator inhibitor type 2 is a down-regulator of the proteolytic cascade consisting of various metalloproteinases, some of which are induced by a carboxy-terminal Raf mutant (RafCT). In conclusion, RafCT induces factors which act in a conflicting manner in respect of carcinogenesis, especially within the proteolytic system of the extracellular matrix.
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PMID:Induction of putative tumor-suppressing genes in Rat-1 fibroblasts by oncogenic Raf-1 as evidenced by robot-assisted complex hybridization. 1104 81

We have investigated mechanisms of mitochondrial stress-induced phenotypic changes and cell invasion in tumorigenic but poorly invasive human pulmonary carcinoma A549 cells that were partly depleted of mitochondrial DNA (mtDNA). Depletion of mtDNA (genetic stress) caused a markedly lower electron transport-coupled ATP synthesis, loss of mitochondrial membrane potential, elevation of steady state [Ca(2+)](c), and notably induction of both glycolysis and gluconeogenic pathway enzymes. Markers of tumor invasion, cathepsin L and TGFbeta1, were overexpressed; calcium-dependent MAP kinases (ERK1 and ERK2) and calcineurin were activated. The levels of anti-apoptotic proteins Bcl2 and Bcl-X(L) were increased, and the cellular levels of pro-apoptotic proteins Bid and Bax were reduced. Both mtDNA-depleted cells (genetic stress) and control cells treated with carbonyl cyanide m-chlorophenylhydrazone (metabolic stress) exhibited higher invasive behavior than control cells in a Matrigel basement membrane matrix assay system. MtDNA-depleted cells stably expressing anti-sense cathepsin L RNA, TGFbeta1 RNA, or treated with specific inhibitors showed reduced invasion. Reverted cells with 80% of control cell mtDNA exhibited marker protein levels, cell morphology and invasive property closer to control cells. Our results suggest that the mitochondria-to-nucleus signaling pathway operating through increased [Ca(2+)](c) plays an important role in cancer progression and metastasis.
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PMID:Mitochondrial stress-induced calcium signaling, phenotypic changes and invasive behavior in human lung carcinoma A549 cells. 1242 Feb 21

Ras expression induces increased expression and altered targeting of lysosomal proteases in multiple cell types, but the specific downstream cytoplasmic signaling pathways mediating these changes have not been identified. In this study, we compared the involvement of 3 major Ras effectors, Raf, phosphatidylinositol 3-kinase (PI3K) and Ral guanine nucleotide exchange factor (RalGEF) in the Ras-mediated alteration of lysosomal protease protein expression and targeting in rat 208F fibroblasts and rat ovarian surface epithelial (ROSE) cells. Effector domain mutants of Ras, constitutively activated variants of Raf, PI3K and RalGEF and pharmacologic inhibitors of MEK and PI3K were utilized to determine the role of these downstream pathways in mediating fibroblast transformation and lysosomal protease regulation in the fibroblasts and epithelial cells. We found that Raf activation of the ERK mitogen-activated protein kinase pathway alone was sufficient to cause morphologic and growth transformation of the fibroblasts and was necessary and sufficient to alter cathepsin L expression and targeting. In contrast, transformation and upregulation of cathepsin L expression in the epithelial cells required the activity of all 3 Ras effectors. Increased protease secretion from the epithelial cells was not observed on ectopic expression of Ras, as it was from the fibroblasts, consistent with the utilization of different signaling pathways in the 2 cell types. In neither cell type did Ras expression increase the expression, processing or secretion of 2 other major lysosomal proteases, cathepsin B and cathepsin D. Thus, Ras utilizes different effectors to mediate transformation and to deregulate cathepsin L expression and secretion in fibroblast and epithelial cells.
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PMID:Enhanced cathepsin L expression is mediated by different Ras effector pathways in fibroblasts and epithelial cells. 1535 30

Depletion of mitochondrial DNA (mtDNA) or treatment with mitochondrial poison CCCP initiates mitochondrial stress signaling, which operates through altered Ca2+ homeostasis. In C2C12 rhabdomyoblasts and A549 human lung carcinoma cells mitochondrial stress signaling activates calcineurin and a number of Ca2+ responsive factors including ATF, NFAT, CEBP/delta and CREB. Additionally, PKC and MAP kinase are also activated. A number of nuclear gene targets including those involved in Ca2+ storage/release (RyR1, calreticulin, calsequestrin), glucose metabolism (hexokinase, pyruvate kinase, Glut4), oncogenesis (TGFbeta1, cathepsin L, IGFR1, melanoma antigen) and apoptosis (Bcl-2, Bid, Bad, p53) are upregulated. Mitochondrial stress in both C2C12 myoblasts and A549 cells induced morphological changes and invasive phenotypes. These cells also showed markedly increased resistance to etoposide-induced apoptosis that is a hallmark of highly invasive tumors. Our results describe a new mechanism of altered nuclear gene expression and phenotypic changes triggered by mitochondrial dysfunction and mtDNA damage.
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PMID:Mitochondria-to-nucleus stress signaling in mammalian cells: nature of nuclear gene targets, transcription regulation, and induced resistance to apoptosis. 1597 49

Platelet-derived growth factor (PDGF)-BB and PDGF-DD mediate mesangial cell proliferation in vitro and in vivo. While PDGF-BB is a ligand for the PDGF alpha- and beta-receptor chains, PDGF-DD binds more selectively to the beta-chain, suggesting potential differences in the biological activities. Signal transduction and regulation of gene expression induced by PDGF-BB and -DD were compared in primary human mesangial cells (HMCs), which expressed PDGF alpha- and beta-receptor subunits. The growth factor concentrations used were chosen based on their equipotency in inducing HMCs proliferation and binding to the betabeta-receptor. Both growth factors, albeit at different concentrations induced phosphorylation and activation of extracellular signal-regulated kinase 1 (ERK1) and ERK2. In addition, PDGFs led to the phosphorylation and activation of signal transducers and activators of transcription 1 (STAT1) and STAT3. HMCs proliferation induced by either PDGF-BB or -DD could be blocked by signal transduction inhibitors of the mitogen-activated protein kinase-, Janus kinase (JAK)/STAT-, or phosphatidyl-inositol 3-kinase pathways. Using a gene chip array and subsequent verification by real-time reverse transcriptase (RT)-polymerase chain reaction, we found that in HMC genes for matrix metalloproteinase 13 (MMP-13) and MMP-14 and, to a low extent, cytochrome B5 and cathepsin L were exclusively regulated by PDGF-BB, whereas no exclusive gene regulation was detected by PDGF-DD. However, at the protein level, both MMP-13 and -14 were equally induced by PDGF-BB and -DD. PDGF-BB and -DD effect similar biological responses in HMCs albeit at different potencies. Rare apparently differential gene regulation did not result in different protein expression, suggesting that in HMCs both PDGFs exert their biological activity almost exclusively via the PDGF beta-receptor.
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PMID:Biological responses to PDGF-BB versus PDGF-DD in human mesangial cells. 1655 24

Skeletal muscle atrophy is a common debilitating feature of many systemic diseases, including cancer. Here we examined the effects of inducing expression of an oncogenic version of the Met receptor (Tpr-Met) in terminally differentiated skeletal muscle. A responder mouse containing the Tpr-Met oncogene and GFP (green fluorescent protein) as a reporter was crossed with a transactivator mouse expressing tTA under the control of the muscle creatine kinase promoter. Tpr-Met induction during fetal development and in young adult mice caused severe muscle wasting, with decreased fiber size and loss of myosin heavy chain protein. Concomitantly, in the Tpr-Met-expressing muscle the mRNA of the E3 ubiquitin ligases atrogin-1/MAFbx, MuRF1, and of the lysosomal protease cathepsin L, which are markers of skeletal muscle atrophy, was significantly increased. In the same muscles phosphorylation of the Met downstream effectors Akt, p38 MAPK, and IkappaBalpha was higher than in normal controls. Induction of Tpr-Met in differentiating satellite cells derived from the double transgenics caused aberrant cell fusion, protein loss, and myotube collapse. Increased phosphorylation of Met downstream effectors was also observed in the Tpr-Met-expressing myotubes cultures. Treatment of these cultures with either a proteasomal or a p38 inhibitor prevented Tpr-Met-mediated myotube breakdown, establishing accelerated protein degradation consequent to inappropriate activation of p38 as the major route for the Tpr-Met-induced muscle phenotype.
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PMID:Conditional activation of MET in differentiated skeletal muscle induces atrophy. 1719

We tested the hypothesis that treatment of rats with curcumin prevents sepsis-induced muscle protein degradation. In addition, we determined the influence of curcumin on different proteolytic pathways that are activated in septic muscle (i.e., ubiquitin-proteasome-, calpain-, and cathepsin L-dependent proteolysis) and examined the role of NF-kappaB and p38/MAP kinase inactivation in curcumin-induced inhibition of muscle protein breakdown. Rats were made septic by cecal ligation and puncture or were sham-operated. Groups of rats were treated with three intraperitoneal doses (600 mg/kg) of curcumin or corresponding volumes of solvent. Protein breakdown rates were measured as release of tyrosine from incubated extensor digitorum longus muscles. Treatment with curcumin prevented sepsis-induced increase in muscle protein breakdown. Surprisingly, the upregulated expression of the ubiquitin ligases atrogin-1 and MuRF1 was not influenced by curcumin. When muscles from septic rats were treated with curcumin in vitro, proteasome-, calpain-, and cathepsin L-dependent protein breakdown rates were reduced, and nuclear NF-kappaB/p65 expression and activity as well as levels of phosphorylated (activated) p38 were decreased. Results suggest that sepsis-induced muscle proteolysis can be blocked by curcumin and that this effect may, at least in part, be caused by inhibited NF-kappaB and p38 activities. The results also suggest that there is not an absolute correlation between changes in muscle protein breakdown rates and changes in atrogin-1 and MuRF1 expression during treatment of muscle wasting.
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PMID:The NF-kappaB inhibitor curcumin blocks sepsis-induced muscle proteolysis. 1838 75

Interleukin (IL)-6 has an important role in inflammatory diseases. Lysosomal enzymes cathepsins are widely expressed as cysteine proteases regulating inflammatory process. Caveolin-1 (Cav-1) is a scaffolding/regulatory membrane protein that interacts with signaling molecules. In this study, we investigated the role of Cav-1 on (1) the productivity, and (2) the enzymatic activity of cathepsin B and L in human gingival fibroblasts (HGFs) treated with IL-6 in the presence of soluble form of IL-6 receptor (sIL-6R). At first, we established the siRNA-mediated Cav-1 down-regulating in vitro systems by transient transfection of Cav-1 siRNA. The siRNA-mediated Cav-1 down-regulated cells were treated with IL-6/sIL-6R for indicated times. Then, cell lysates were collected, and examined the IL-6-induced signaling pathway, cathepsin B and L production, and measurement of cathepsins activity. To investigate the cathepsin L activity, cathepsin-(B + L) activity was measured after pretreatment with CA-074Me, a specific inhibitor for cathepsin B. We found that IL-6/sIL-6R enhanced significantly both production and activity of cathepsin B and L in HGFs. Interestingly, IL-6-mediated phosphorylation of both p44/42 MAPK and JNK was dramatically suppressed in Cav-1 down-regulated HGFs treated with IL-6/sIL-6R. In addition, both production and activity of cathepsin B and L were also significantly suppressed. Importantly, we demonstrated that JNK inhibition, but not p44/42 MAPK inhibition, significantly diminished IL-6/sIL-6R-induced cathepsin B and L production. Taken together, we concluded that IL-6/sIL-6R enhances cathepsin B and L production via IL-6/sIL-6R-mediated Cav-1-JNK-AP-1 pathway in HGFs. Our findings indicate that Cav-1 might be a therapeutic target for IL-6-mediated tissue degradation in periodontitis.
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PMID:IL-6/sIL-6R enhances cathepsin B and L production via caveolin-1-mediated JNK-AP-1 pathway in human gingival fibroblasts. 1854 49


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