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)

Vascular endothelial growth factor (VEGF) has an important function in renal vascular ontogenesis and is constitutively expressed in podocytes of the adult kidney. The ability of VEGF to be chemotactic for monocytes and to increase the activity of collagenase and plasminogen activator may have implications for renal development and renal disease. In humans, the cellular actions of VEGF depend on binding to two specific receptors: Flt-1 and KDR. The aims of this study were: (1) to localize VEGF receptor proteins in human renal ontogenesis; (2) to quantify VEGF binding in human fetal and adult kidney; and (3) to dissect the binding into its two known components: the KDR and Flt-1 receptors. The latter aim was achieved by competitive binding of VEGF and placenta growth factor-2, which only binds to Flt-1. Quantification of 125I-VEGF binding sites was performed by autoradiography and computerized densitometry. By double-label immunohistochemistry, VEGF receptor proteins were localized solely to endothelial cells of preglomerular vessels, glomeruli, and postglomerular vessels. In developing glomeruli, VEGF receptor protein appeared as soon as endothelial cells were positive for von Willebrand factor. Specific 125I-VEGF binding could be localized to renal arteries and veins, glomeruli, and the tubulointerstitial capillary network in different developmental stages. Affinity (Kd) of adult (aK) and fetal (fK) kidneys was: Kd: glomeruli 38.6 +/- 11.2 (aK, n = 5), 36.3 +/- 7.1 (fK, n = 5); cortical tubulointerstitium 19.4 +/- 2.6 (aK, n = 5), 11.6 +/- 7.0 (fK, n = 5) pmol. Placenta growth factor-2 displaced VEGF binding in all renal structures by approximately 60%. VEGF receptor proteins thus were found only in renal endothelial cells. A coexpression of both VEGF binding sites could be shown, with Flt-1 demonstrating the most abundant VEGF receptor binding sites in the kidney. These studies support the hypothesis of a function for VEGF in adult kidney that is independent of angiogenesis.
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PMID:Receptors of vascular endothelial growth factor/vascular permeability factor (VEGF/VPF) in fetal and adult human kidney: localization and [125I]VEGF binding sites. 962 Dec 86

Activation of c-Jun N-terminal kinases (JNKs)/stress-activated protein kinases is an early response of cells upon exposure to DNA-damaging agents. JNK-mediated phosphorylation of c-Jun is currently understood to stimulate the transactivating potency of AP-1 (e.g., c-Jun/c-Fos; c-Jun/ATF-2), thereby increasing the expression of AP-1 target genes. Here we show that stimulation of JNK1 activity is not a general early response of cells exposed to genotoxic agents. Treatment of NIH 3T3 cells with UV light (UV-C) as well as with methyl methanesulfonate (MMS) caused activation of JNK1 and an increase in c-Jun protein and AP-1 binding activity, whereas antineoplastic drugs such as mafosfamide, mitomycin C, N-hydroxyethyl-N-chloroethylnitrosourea, and treosulfan did not elicit this response. The phosphatidylinositol 3-kinase inhibitor wortmannin specifically blocked the UV-stimulated activation of JNK1 but did not affect UV-driven activation of extracellular regulated kinase 2 (ERK2). To investigate the significance of JNK1 for transactivation of c-jun, we analyzed the effect of UV irradiation on c-jun expression under conditions of wortmannin-mediated inhibition of UV-induced stimulation of JNK1. Neither the UV-induced increase in c-jun mRNA, c-Jun protein, and AP-1 binding nor the activation of the collagenase and c-jun promoters was affected by wortmannin. In contrast, the mitogen-activated protein kinase/ERK kinase inhibitor PD98056, which blocked ERK2 but not JNK1 activation by UV irradiation, impaired UV-driven c-Jun protein induction and AP-1 binding. Based on the data, we suggest that JNK1 stimulation is not essential for transactivation of c-jun after UV exposure, whereas activation of ERK2 is required for UV-induced signaling leading to elevated c-jun expression.
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PMID:Activation of c-Jun N-terminal kinase 1 by UV irradiation is inhibited by wortmannin without affecting c-iun expression. 1002 64

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

Mitogen-activated protein kinase (MAPK) cascades are involved in inflammation and tissue destruction in rheumatoid arthritis (RA). In particular, c-Jun N-terminal kinase (JNK) is highly activated in RA fibroblast-like synoviocytes and synovium. However, defining the precise function of this kinase has been difficult because a selective JNK inhibitor has not been available. We now report the use of a novel selective JNK inhibitor and JNK knockout mice to determine the function of JNK in synoviocyte biology and inflammatory arthritis. The novel JNK inhibitor SP600125 (anthra[1,9-cd]pyrazol-6(2H)-one) completely blocked IL-1--induced accumulation of phospho-Jun and induction of c-Jun transcription in synoviocytes. Furthermore, AP-1 binding and collagenase mRNA accumulation were completely suppressed by SP600125. In contrast, complete inhibition of p38 had no effect, and ERK inhibition had only a modest effect. The essential role of JNK was confirmed in cultured synoviocytes from JNK1 knockout mice and JNK2 knockout mice, each of which had a partial defect in IL-1--induced AP-1 activation and collagenase-3 expression. Administration of SP600125 modestly decreased the rat paw swelling in rat adjuvant-induced arthritis. More striking was the near-complete inhibition of radiographic damage that was associated with decreased AP-1 activity and collagenase-3 gene expression. Therefore, JNK is a critical MAPK pathway for IL-1--induced collagenase gene expression in synoviocytes and in joint arthritis, indicating that JNK is an important therapeutic target for RA.
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PMID:c-Jun N-terminal kinase is required for metalloproteinase expression and joint destruction in inflammatory arthritis. 1145 69

Matrix metalloproteinase-1 (MMP-1) is one of only a few enzymes with the ability to degrade the stromal collagens (types I and III) at neutral pH, and high expression of MMP-1 has been associated with aggressive and invasive cancers. We recently reported a single nucleotide insertion/deletion polymorphism (SNP) in the collagenase-1 (MMP-1) promoter (Rutter et al. [1998] Can. Res. 58:5321-5325), where the insertion of an extra guanine (G) at -1607 bp creates the sequence, 5'-GGAA-3 (2G allele), compared to the sequence 5'-GAA-3' (1G allele). The presence of 2G constitutes a binding site for the ETS family of transcription factors, and increases MMP-1 transcription in fibroblasts and A2058 melanoma cells cultured in vitro. In addition, the presence of the 2G allele has been linked to several aggressive malignancies as well as to enhanced expression of MMP-1. In this study, we describe a melanoma cell line, VMM5, that is 1G homozygous, but that is invasive and expresses high levels of MMP-1 constitutively. The high level of MMP-1 expression in VMM5 cells is due to the utilization of both the p38 and ERK1/2 transduction pathways. In contrast, in the A2058 cell line, which also expresses MMP-1 constitutively and which is 2G homozygous, only the ERK pathway is activated. Thus, our data suggest that in the absence of 2G allele and in the presence of the appropriate transcription factors, tumor cells may use alternative signal/transduction pathways and cis-acting sequences to achieve high levels of MMP-1 expression, which contribute to the ability of tumor cells to invade, regardless of their genotype.
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PMID:High levels of MMP-1 expression in the absence of the 2G single nucleotide polymorphism is mediated by p38 and ERK1/2 mitogen-activated protein kinases in VMM5 melanoma cells. 1211

Changes in cellular morphology induced as a consequence of direct perturbation of cytoskeletal structure with network-specific targeting agents (i.e. microfilament- or microtubule-disrupting drugs) results in the stimulated expression of a specific subset of genes. Transcription of c-fos, collagenase, transforming growth factor-beta, actin, urokinase plasminogen activator and its type-1 inhibitor (PAI-1) appears to be particularly responsive to shape-activated signaling pathways. Cytochalasin D (CD) or colchicine treatment of contact-inhibited and serum-deprived vascular smooth muscle (R22) cells was used, therefore, as a model system to evaluate morphology-associated controls on PAI-1 gene regulation in the absence of added growth factors. PAI-1 transcript levels in quiescent R22 cells increased rapidly and in a CD-concentration-dependent fashion, with kinetics of expression paralleling the morphological changes. Colchicine concentrations that effectively disrupted microtubule structure and reduced the cellular 'footprint' area (to approximately that of CD treatment) also stimulated PAI-1 synthesis. Shape-related increases in PAI-1 mRNA synthesis were ablated by prior exposure to actinomycin D. Unlike the mechanism of induction in growth-factor-stimulated cells, CD- and colchicine-induced PAI-1 expression required on-going protein synthesis (i.e. it was a secondary response). Although PAI-1 is a TGF-beta-regulated gene and TGF-beta expression is also shape dependent, an autocrine TGF-beta loop was not a factor in CD-initiated PAI-1 transcription. Since CD exposure resulted in actin microfilament disruption and subsequent morphological changes, with uncertain effects on interactions between signaling intermediates or 'scaffold' structures, a pharmacological approach was selected to probe the pathways involved. Signaling events leading to PAI-1 induction were compared with colchicine-treated cells. CD- as well as colchicine-stimulated PAI-1 expression was effectively and dose dependently attenuated by the MEK inhibitor PD98059 (in the 10 to 25 microM concentration range), consistent with the known MAP kinase dependency of PAI-1 synthesis in growth-factor-stimulated cells. Reduced PAI-1 mRNA levels upon exposure to genistein prior to CD addition correlated with inhibition of ERK1/2 activity, implicating a tyrosine kinase in shape-dependent MEK activation. Src-family kinases, moreover, appeared to be specific upstream elements in the CD- and colchicine-dependent pathways of PAI-1 transcription since both agents effectively activated pp60(c-src) kinase activity in quiescent R22 cells. The restrictive (src-family) kinase inhibitor PP1 completely inhibited induced, as well as basal, ERK activity in a coupled immunoprecipitation myelin-basic-protein-phosphorylation assay and ablated shape-initiated PAI-1 mRNA expression. These data suggest that PP1-sensitive tyrosine kinases are upstream intermediates in cell-shape-associated signaling pathways resulting in ERK1/2 activation and subsequent PAI-1 transcription. In contrast to the rapid and transient kinetics of ERK activity typical of serum-stimulated cells, the ERK1/2 response to CD and colchicine is both delayed and relatively sustained. Collectively, these data support a model in which MEK is a focal point for the convergence of shape-initiated signaling events leading to induced PAI-1 transcription.
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PMID:MEK/ERK pathway mediates cell-shape-dependent plasminogen activator inhibitor type 1 gene expression upon drug-induced disruption of the microfilament and microtubule networks. 1211 65

The accessibility of various solid supports (TentaGel, PEGA 1900, and beaded controlled pore glasses (CPGs)) to a range of enzymes was investigated. The different beaded materials were loaded with the peptide 4-cyanobenzamide-Gly-Pro-Leu-Gly-Leu-Phe-Ala-Arg-OH and incubated with the enzymes MMP-12 (22 kDa), thermolysin (35 kDa), MMP-13 (42.5 kDa), clostridium collagenase (68 kDa), and NEP (90 kDa). The absence/presence of the cyano stretching frequency was measured by means of confocal Raman microscopy. It was found that none of the investigated enzymes could enter the polymer matrices of TentaGel. PEGA 1900 was compatible only with the two smallest enzymes, while beaded CPG was successful even with NEP (90 kDa), proving its superiority over other materials in terms of bio-compatibility.
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PMID:Enzyme accessibility and solid supports: which molecular weight enzymes can be used on solid supports? An investigation using confocal Raman microscopy. 1220 3

From collagenase digests of human thyroid, endothelial cells were separated from follicular cells by their greater adherence to gelatin-coated plates. Endothelial cells were further purified using fluorescence-activated cell sorting, selecting for cells expressing factor VIII-related antigen. Isolated cells were negative for thyroglobulin and calcitonin when examined by immunostaining. The receptor for the angiopoietins, Tie-2, was expressed by the cells, and expression was increased by agents that elevate cAMP. Nitric oxide synthase (NOS) 3, the endothelial form of NOS, was expressed by the cells and similarly regulated. Cells responded strongly to the mitogen fibroblast growth factor (FGF)-2 in growth assays but only weakly to vascular endothelial growth factor (VEGF). VEGF was, however, able to stimulate nitric oxide release from the cells consistent with their endothelial origin. The FGF receptor (FGFR1) was full length (120 kDa) and immunolocalized to the cytosol and nucleus. Thyrotropin (TSH) did not regulate FGFR1, but its expression was increased by VEGF. Thrombospondin, a product of follicular cells, was a growth inhibitor, but neither TSH nor 3,5,3'-triiodothyronine had direct mitogenic effects. Thyroid follicular cell conditioned medium contained plasminogen activator activity and stimulated the growth of the endothelial cells, but when treated with plasminogen to produce the endothelial-specific inhibitor, angiostatin, growth was inhibited. Human thyroid endothelial cell cultures will be invaluable in determining the cross talk between endothelial and follicular cells during goitrogenesis.
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PMID:Isolation and characterization of human thyroid endothelial cells. 1962 78

Replicative senescence is characterized by numerous phenotypic alterations including loss of proliferative capacity and numerous changes in gene expression such as impaired serum inducibility of the immediate early gene c-fos and increased expression of collagenase. Transcription of c-fos in response to mitogens depends on the activation of a multiprotein complex formed on the c-fos serum response element (SRE), which includes the transcription factors serum response factor (SRF) and ternary complex factor (TCF). TCF is activated after phosphorylation by the Extracellular signals Regulated Kinase 1 and 2 (ERK1/2), two kinases of the Raf/MEK/ERK signaling pathway. We have previously demonstrated that collagenase expression is under positive regulation by the transcription factor FKHRL1 and that this transcription factor is under negative regulation by the phosphatidylinositol 3-kinase(PI3K)/Akt(PKB) pathway. Although total activity of ERK and Akt was similar in total cell lysates from early and late passage fibroblasts our data indicate that in senescent cells neither ERK nor Akt are able to phosphorylate efficiently their nuclear targets. Our findings suggest that although they can be fully activated in the cytosol of both early and late passage cells, the Raf/MEK/ERK and the PI3K/Akt pathways, which are essential for cellular proliferation, are down regulated in the nuclei of senescent cells.
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PMID:Role of the Raf/MEK/ERK and the PI3K/Akt(PKB) pathways in fibroblast senescence. 1247 Aug 26

Several members of the ETS family of transcription factors contribute to tumorigenesis in many different tissues, including breast epithelium. The ESX gene is an epithelial-specific Ets member that is particularly relevant to breast cancer. ESX is amplified in early breast cancers, it is overexpressed in human breast ductal carcinoma in situ, and there may be a positive feedback loop between the HER2/neu proto-oncogene and ESX. Despite this progress in our understanding of ESX, its ability to regulate tumor-related gene expression and to modulate breast cell survival, remain unknown. Here we show that HA-ESX stimulates the collagenase and HER2/neu promoters, but fails to activate an intact stromelysin promoter. However, HA-ESX activates, in a dose-dependent manner, a heterologous promoter containing eight copies of the Ets binding site derived from the stromelysin gene (p8Xpal-CAT). Analysis of the ability of constructs encoding nine Ets family members to activate the HER2/neu promoter revealed three patterns of gene activation: (1) no effect or repressed promoter activity (Elk-1 and NET); (2) intermediate activity (ER81, GABP, ESX, and HA-Ets-2); and, (3) maximal activity (Ets-1, VP-16-Ets-1, and EHF). Based on these observations, we also determined whether ESX is capable of conferring a survival phenotype upon immortalized, but nontransformed and ESX negative MCF-12A human breast cells. Using a colony formation assay, we found that HA-ESX and HA-Ets-2, mediated MCF-12A cell survival rates that approached those generated by oncogenic V12 Ras, whereas empty vector resulted in negligible colony formation. By contrast, in immortalized and transformed T47D breast cancer cells, which express both HER2/neu and ESX, we found that antisense and dominant-negative HA-ESX inhibited T47D colony formation, whereas control vector allowed formation of many colonies. These results are significant because they show that HA-ESX is able to differentially activate several malignancy-associated gene promoters, and that ESX expression is required for cellular survival of nontransformed MCF-12A and transformed T47D human mammary cells.
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PMID:The epithelial-specific ETS transcription factor ESX/ESE-1/Elf-3 modulates breast cancer-associated gene expression. 1271 34


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