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

Diesel exhaust particles (DEP) induce a proinflammatory response in human bronchial epithelial cells (16HBE) characterized by the release of proinflammatory cytokines after activation of transduction pathways involving MAPK and the transcription factor NF-kappaB. Because cellular effects induced by DEP are prevented by antioxidants, they could be mediated by reactive oxygen species (ROS). Using fluorescent probes, we detected ROS production in bronchial and nasal epithelial cells exposed to native DEP, organic extracts of DEP (OE-DEP), or several polyaromatic hydrocarbons. Carbon black particles mimicking the inorganic part of DEP did not increase ROS production. DEP and OE-DEP also induced the expression of genes for phase I [cytochrome P-450 1A1 (CYP1A1)] and phase II [NADPH quinone oxidoreductase-1 (NQO-1)] xenobiotic metabolization enzymes, suggesting that DEP-adsorbed organic compounds become bioavailable, activate transcription, and are metabolized since the CYP1A1 enzymatic activity is increased. Because NQO-1 gene induction is reduced by antioxidants, it could be related to the ROS generated by DEP, most likely through the activation of the stress-sensitive Nrf2 transcription factor. Indeed, DEP induced the translocation of Nrf2 to the nucleus and increased protein nuclear binding to the antioxidant responsive element. In conclusion, we show that DEP-organic compounds generate an oxidative stress, activate the Nrf2 transcription factor, and increase the expression of genes for phase I and II metabolization enzymes.
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PMID:Involvement of reactive oxygen species in the metabolic pathways triggered by diesel exhaust particles in human airway epithelial cells. 1273 81

Vascular endothelial cells respond to nitric oxide by activating MAPK pathways and upregulating stress-activated proteins such as gamma-glutamylcysteine synthetase (gamma-GCS) and heme oxygenase-1 (HO-1). Since consensus sequences for the antioxidant response element (ARE) are found in the promoters of the gamma-GCS and HO-1 genes, we examined nuclear translocation of Nrf2, a CNC-bZIP protein which binds to and activates the ARE. We found a dramatic increase in Nrf2 nuclear translocation 1-8h following the nitric oxide donor spermine NONOate. Translocation was inhibited by pretreatment of cells with N-acetylcysteine suggesting involvement of an oxidative mechanism in this response. Translocation was also blocked by PD 98059 and SB 203580, inhibitors of ERK and p38 pathways, respectively. In addition to effects on Nrf2 subcellular localization, spermine NONOate increased Nrf2 protein levels by a mechanism which was inhibited by PD 98059. Pretreatment with N-acetylcysteine, PD 98059, and SB 203580 decreased HO-1 upregulation in spermine NONOate-treated cells. These results suggest that ERK and p38 pathways may regulate nitric oxide-mediated adaptive responses in vascular endothelium via translocation of Nrf2 and activation of the ARE.
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PMID:Nitric oxide stimulates Nrf2 nuclear translocation in vascular endothelium. 1287 7

The antioxidant protein peroxiredoxin (Prx) I is a thioredoxin peroxidase that is involved in the regulation of proliferation and differentiation of mammalian cells. Here, it is shown that Prx I gene expression was induced transcriptionally by the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) in cultured rat liver tissue macrophages and RAW264.7 monocytic cells. TPA-dependent induction of Prx I gene expression was mediated by two proximal activator protein-1 sites of the rat Prx I promoter region that were nuclear targets of c-Jun as determined by transfection studies with luciferase reporter gene constructs and electrophoretic mobility shift assays. The transcription factor Nrf2, however, was not involved in the regulation of Prx I promoter activity. Prx I gene induction by TPA was decreased by protein kinase C inhibitors and overexpressed dominant negative forms of Ras and MEKK1, but not Raf-1. The p38 MAPK inhibitor SB202190 and overexpression of dominant negative mutants of MAPK kinase 4 (MKK4), MKK6, and p38 inhibited the TPA-dependent induction of Prx I gene transcription. In contrast, inhibitors of the JNK, SP600125, and the NF-kappaB signaling pathway, caffeic acid phenethyl ester, respectively, as well as overexpressed dominant negative MKK7 and IkappaB, had no effect on the up-regulation of Prx I reporter gene activity by TPA. Cotransfection of wild-type p38alpha and p38beta, but not that of p38gamma and p38delta, increased Prx I promoter activity. The data indicate that a protein kinase C, Ras, MEKK1, p38 MAPK signaling pathway plays a major role for the transcriptional up-regulation of Prx I gene expression.
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PMID:Phorbol ester-dependent activation of peroxiredoxin I gene expression via a protein kinase C, Ras, p38 mitogen-activated protein kinase signaling pathway. 1296 Jan 65

The export of certain nuclear proteins is involved in the regulation of various nuclear functions, including transcription. In some cases, the export of target proteins is induced upon environmental or cellular cues, resulting in conditional gene expression. The small Maf proteins appear to be critical regulators of heme oxygenase (HO)-1, an anti-oxidant defense enzyme that degrades heme into iron, carbon monoxide, and biliverdin. Although ho-1 is repressed by Bach1/small Maf heterodimers, it is activated by Nrf2/small Maf heterodimers, indicating that Bach1 and Nrf2 compete with each other. We anticipated that the nuclear concentration of Bach1 might be regulated to ensure that the entire system effectively responds to various stimuli. We carried out detailed domain analysis of Bach1 in an effort to understand how various inducers of HO-1 inactivate Bach1. We show here that cadmium, a strong inducer of HO-1, activates the nuclear export of Bach1. This cadmium-induced export of Bach1 was mediated in trans by its C-terminal region that is conserved between Bach1 and Bach2. The nuclear export of Bach2 was also induced by cadmium, indicating that the cadmium responsibility is shared between Bach1 and Bach2. The nuclear export of Bach1 was dependent on Crm1/Exportin-1 as well as the extracellular signal-regulated kinase-1/2 (ERK1/2) activity. These results indicate that the nuclear export of Bach1 constitutes an important regulatory mechanism to relieve the Bach1-mediated repression of genes such as ho-1.
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PMID:Cadmium induces nuclear export of Bach1, a transcriptional repressor of heme oxygenase-1 gene. 1450 88

Recent studies indicate a potential role for Fra-1, a heterodimeric partner of activator protein (AP)-1, in toxicant-induced epithelial injury, repair, and cellular transformation. Here we have investigated the effects of diesel exhaust particles (DEP) on fra-1 expression in C10 cells, a murine lung epithelial cell line. DEP markedly upregulated fra-1, but not fra-2, expression. The increase in fra-1 mRNA expression correlated well with its protein- and DNA-binding activity. DNA-binding assays also revealed a predominant presence of Jun-B and Jun-D in the AP-1 complex. Interestingly, DEP did not alter Jun-B and Jun-D protein levels. Transcriptional analysis revealed that fra-1 induction is regulated in part at the transcriptional level. The -379 to +32 bp 5'-flanking region mediated this induction. Furthermore, inhibitors of ERK1/2, JNK1, and p38 mitogen-activated protein kinases (MAPKs) significantly suppressed DEP-stimulated fra-1 transcription, suggesting their involvement in the induction process. Consistent with this finding, DEP stimulated phosphorylation of ERK1/2, JNK1, and p38 MAPKs with a distinct activation pattern. Overexpression of Fra-1 downregulated c-Jun and Nrf2 enhanced AP-1- and ARE-mediated reporter gene expression, respectively. In contrast, Fra-1 had the opposite effect on matrix metalloproteinase (MMP)-9 promoter activity. In particular, it bound to the functional AP-1 site of the MMP-9 promoter after DEP stimulation. Consistent with this result, DEP also markedly upregulated MMP-9 promoter activity. Collectively, these findings suggest that fra-1 induction by DEP may play a role in selectively regulating gene expression involved in alveolar epithelial cell injury and repair.
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PMID:DEP-induced fra-1 expression correlates with a distinct activation of AP-1-dependent gene transcription in the lung. 1456 43

The phosphatidylinositol 3-kinase (PI3K)/Akt pathway elicits a survival signal against multiple apoptotic insults. In addition, phase II enzymes such as heme oxygenase-1 (HO-1) protect cells against diverse toxins and oxidative stress. In this work, we describe a link between these defense systems at the level of transcriptional regulation of the antioxidant enzyme HO-1. The herb-derived phenol carnosol induced HO-1 expression at both mRNA and protein levels. Luciferase reporter assays indicated that carnosol targeted the mouse ho1 promoter at two enhancer regions comprising the antioxidant response elements (AREs). Moreover, carnosol increased the nuclear levels of Nrf2, a transcription factor governing AREs. Electrophoretic mobility shift assays and luciferase reporter assays with a dominant-negative Nrf2 mutant indicated that carnosol increased the binding of Nrf2 to ARE and induced Nrf2-dependent activation of the ho1 promoter. While investigating the signaling pathways responsible for HO-1 induction, we observed that carnosol activated the ERK, p38, and JNK pathways as well as the survival pathway driven by PI3K. Inhibition of PI3K reduced the increase in Nrf2 protein levels and activation of the ho1 promoter. Expression of active PI3K-CAAX (where A is aliphatic amino acid) was sufficient to activate AREs. The use of dominant-negative mutants of protein kinase Czeta and Akt1, two kinases downstream from PI3K, demonstrated a requirement for active Akt1, but not protein kinase Czeta. Moreover, the long-term antioxidant effect of carnosol was partially blocked by PI3K or HO-1 inhibitors, further demonstrating that carnosol attenuates oxidative stress through a pathway that involves PI3K and HO-1.
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PMID:Regulation of heme oxygenase-1 expression through the phosphatidylinositol 3-kinase/Akt pathway and the Nrf2 transcription factor in response to the antioxidant phytochemical carnosol. 1468 81

Chemoprevention is a cancer preventive strategy to inhibit, delay or reverse carcinogenesis using naturally occurring or synthetic chemical agents. Numerous epidemiological studies as well as experimental animal studies clearly demonstrate that high intake of cruciferous vegetables protects against tumorigenesis. Thus, cruciferous vegetables have been of great interest for potential use in the chemoprevention of cancer. Cruciferous vegetables are rich source of glucosinolates, which are degraded into isothiocyanates by enzymatic action of plant-specific myrosinase or intestinal flora in the body. It appears that significant portion of the chemopreventive effects of isothiocyanates may be associated with the inhibition of the metabolic activation of carcinogens by cytochrome P450s (Phase I), coupled with strong induction of Phase II detoxifying and cellular defensive enzymes. Inductions of Phase II cellular enzymes are largely mediated by the antioxidant responsive element (ARE), which is regulated by the transcriptional factor, Nrf2. Additional potent regulatory mechanisms of Nrf2 include the different signaling kinase pathways (MAPK, PI3K, PKC and PERK) as well as other non-kinase dependent mechanisms. Moreover, apoptosis and cell cycle perturbations appear to be yet another potential chemopreventive mechanisms elicited by isothiocyanates, especially with respect to the effects on pre-initiated or initiated tumor cells. Finally, modulation of other critical signaling mediators, including the NF-kappaB and AP-1 by a wide array of chemopreventive agents including isothiocyanates may also contribute to the overall chemopreventive mechanisms.
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PMID:Chemoprevention by isothiocyanates and their underlying molecular signaling mechanisms. 1547 60

Diallyl sulfide (DAS), is protective against chemically induced heptotoxicity, mutagenesis, and carcinogenesis. The mechanism of its protective effects is not fully understood. In this study, we found that DAS can induce the expression of heme oxygenase-1 (HO-1), which plays a critical role in the cell defense system against oxidative stress. DAS causes a dose- and time-dependent increase of HO-1 protein and mRNA level without toxicity in HepG2 cells. DAS-induced HO-1 protein expression is dependent on newly synthesized mRNA and newly synthesized protein. DAS increases Nrf2 protein expression, nuclear translocation, and DNA-binding activity. The MAP kinase ERK is activated by DAS. Both ERK and p38 pathways play an important role in DAS-induced Nrf2 nuclear translocation and ho-1 gene activation. DAS stimulates a transient increase of reactive oxygen species (ROS). N-Acetyl-cysteine blocked this increase of ROS production as well as DAS-induced ERK activation, Nrf2 protein expression and nuclear translocation, and ho-1 gene activation. The increase in HO-1 produced by DAS protected the HepG2 cells against toxicity by hydrogen peroxide or arachidonic acid. These results suggest that DAS induces ho-1 through production of ROS, and Nrf2 and MAPK (ERK and p38) mediate this induction. Induction of ho-1 may play a role in the protective effects of DAS.
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PMID:Diallyl sulfide induces heme oxygenase-1 through MAPK pathway. 1554 64

Chlorogenic acid, the ester of caffeic acid with quinic acid, is one of the most abundant polyphenols in the human diet. The antioxidant and anticarcinogenic properties of chlorogenic acid have been established in animal studies. However, little is known about the molecular mechanisms through which chlorogenic acid inhibits carcinogenesis. In this study, we found that chlorogenic acid inhibited the proliferation of A549 human cancer cells in vitro. The results of the soft agar assay indicated that chlorogenic acid suppressed 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced neoplastic transformation of JB6 P+ cells in a dose-dependent manner. Pretreatment of JB6 cells with chlorogenic acid blocked UVB- or TPA-induced transactivation of AP-1 and NF-kappaB over the same dose range. At low concentrations, chlorogenic acid decreased the phosphorylation of c-Jun NH2-terminal kinases, p38 kinase, and MAPK kinase 4 induced by UVB/12-O-tetradecanoylphorbol-13-acetate, yet higher doses were required to inhibit extracellular signal-regulated kinases. Chlorogenic acid also increased the enzymatic activities of glutathione S-transferases (GST) and NAD(P)H: quinone oxidoreductase. Further studies indicated that chlorogenic acid could stimulate the nuclear translocation of Nrf2 (NF-E2-related factor) as well as subsequent induction of GSTA1 antioxidant response element (ARE)-mediated GST activity. The phosphatidylinositol 3-kinase pathway might be involved in the activation of Nrf2 translocation. These results provide the first evidence that chlorogenic acid could protect against environmental carcinogen-induced carcinogenesis and suggest that the chemopreventive effects of chlorogenic acid may be through its up-regulation of cellular antioxidant enzymes and suppression of ROS-mediated NF-kappaB, AP-1, and MAPK activation.
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PMID:Inhibition of activator protein-1, NF-kappaB, and MAPKs and induction of phase 2 detoxifying enzyme activity by chlorogenic acid. 1594 51

Oxidized low-density lipoproteins (LDL) play a central role in atherogenesis and induce expression of the antioxidant stress protein heme oxygenase 1 (HO-1). In the present study we investigated induction of HO-1 and adaptive increases in reduced glutathione (GSH) in human aortic smooth muscle cells (SMC) in response to moderately oxidized LDL (moxLDL, 100 microg protein/ml, 24 h), a species containing high levels of lipid hydroperoxides. Expression and activity of HO-1 and GSH levels were elevated to a greater extent by moxLDL than highly oxidized LDL but unaffected by native or acetylated LDL. Inhibitors of protein kinase C (PKC) or mitogen-activated protein kinases (MAPK) p38(MAPK) and MEK or c-jun-NH2-terminal kinase (JNK) significantly attenuated induction of HO-1. Phosphorylation of p38(MAPK), extracellular signal-regulated kinase (ERK1/2), or JNK and nuclear translocation of the transcription factor Nrf2 were enhanced following acute exposure of SMC to moxLDL (100 microg protein/ml, 1-2 h). Pretreatment of SMC with the antioxidant vitamin C (100 microM, 24 h) attenuated the induction of HO-1 by moxLDL. Native and oxidized LDL did not alter basal levels of intracellular ATP, mitochondrial dehydrogenase activity, or expression of the lectin-like oxidized LDL receptor (LOX-1) in SMC. These findings demonstrate for the first time that activation of PKC, p38(MAPK), JNK, ERK1/2, and Nrf2 by oxidized LDL in human SMC leads to HO-1 induction, constituting an adaptive response against oxidative injury that can be ameliorated by vitamin C.
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PMID:Induction of heme oxygenase 1 by moderately oxidized low-density lipoproteins in human vascular smooth muscle cells: role of mitogen-activated protein kinases and Nrf2. 1596 14


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