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)

Accumulation of advanced glycation endproduct (AGE) has been implicated in the pathogenesis of diabetic complications. However, the precise role and mechanism behind AGE-associated diabetic heart injury are not fully clear. This study was designed to evaluate the effect of AGE on accumulation of reactive oxygen species (ROS), apoptosis, mitogen-activated protein kinase (MAPK) activation and nuclear O-GlcNAcylation in fetal human cardiac myocytes. Myocytes were maintained for 24-72 h in a defined culture medium containing high glucose, the AGE carbon precursor methylglyoxal (MG), and MG-AGE derived from MG and bovine serum albumin (BSA). Generation of ROS was detected by 5-(6)-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate. Apoptosis was evaluated by caspase-3 activity and quantitative DNA fragmentation. Both high glucose (25.5 mM) and MG (200 microM) significantly enhanced ROS and AGE formation with greater effects elicited by MG. Both high glucose and MG-AGE significantly facilitated apoptosis with a more predominant effect from MG-AGE. In addition, phosphorylation of MAPK cascade [extracellular signal-regulated kinase-1/2 (ERK1/2) and p38] and nuclear O-GlcNAcylation were enhanced in MG-AGE-treated myocytes, similar to those elicited by high glucose. MG-AGE-induced phosphorylation of ERK1/2 and p38 was nullified by neutralizing AGE with specific anti-AGE antibody but not nonspecific antiserum. Collectively, these results indicated that AGE or its precursor MG may trigger ROS generation, apoptosis, MAPK activation and nuclear O-GlcNAcylation in human cardiac myocytes, in a manner reminiscent of high extracellular glucose.
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PMID:Advanced glycation endproduct induces ROS accumulation, apoptosis, MAP kinase activation and nuclear O-GlcNAcylation in human cardiac myocytes. 1717 44

Tetrabromobisphenol-A (TBBPA) is one of the worlds most widely used brominated flame retardant. The present study reports effects of TBBPA on primary cultures of cerebellar granule cells (CGC). Using the trypan blue exclusion assay, we show that TBBPA induces death of CGC at low micro molar concentrations. Cell death was reduced by the NMDA receptor antagonist MK-801 (3 microM), the antioxidant vitamin E (50 microM), and in calcium-free buffer. We further demonstrate that TBBPA's toxicity was accompanied by apoptosis-like nuclear shrinkage, chromatin condensation, and DNA fragmentation. Other hallmarks of apoptosis such as caspase activity were, however, absent, indicating an atypical form of apoptosis. TBBPA increased intracellular free calcium in a concentration-dependent manner. TBBPA also induced an increase in extracellular glutamate in a time-dependent manner. TBBPA gave a concentration-dependent increase information reactive oxygen species (ROS) of measured with 2,7-dichlorofluorescein diacetate. The ROS formation was inhibited by the extracellular signal-regulated protein kinase (ERK) inhibitor U0126 (10 microM), the tyrosine kinase inhibitor erbstatin-A (25 microM), eliminating calcium from the buffer and by the superoxide dismutase inhibitor diethyldithio-carbamic acid (DDC, 100 microM). Further analysis with Western blot confirmed phosphorylation of ERK1/2 after exposure to TBBPA. We found that TBBPA induces ROS formation, increases intracellular calcium, extracellular glutamate, and death of CGC in vitro at concentrations comparable to those of polychlorinated biphenyl. These findings implicate TBBPA as a predicted environmental toxin and bring out the importance of awareness of its hazardous effects.
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PMID:In vitro toxicity of tetrabromobisphenol-A on cerebellar granule cells: cell death, free radical formation, calcium influx and extracellular glutamate. 1720 76

Small cell lung cancer (SCLC) is a difficult disease to treat and sometimes has overexpression or mutation of c-Met receptor tyrosine kinase. The effects of c-Met/hepatocyte growth factor (c-Met/HGF, ligand for c-Met) on activation of reactive oxygen species (ROS) was determined. HGF stimulation of c-Met-overexpressing H69 SCLC cells (40 ng/ml, 15 min) resulted in an increase of ROS, measured with fluorescent probe 2'-7'-dichlorofluorescein diacetate (DCFH-DA) or dihydroethidine (DHE) but not in c-Met-null H446 cells. ROS was increased in juxtamembrane (JM)-mutated variants (R988C and T1010I) of c-Met compared with wild-type c-Met-expressing cells. ROS was significantly inhibited by preincubation of SCLC cells with pyrrolidine dithiocarbamate (PDTC, 100 microM) and/or SU11274 (small molecule c-Met tyrosine kinase inhibitor, 2 microM) for 3 h. PDTC and SU11274 also abrogated the HGF proliferative signal and cell motility in a cooperative fashion. H(2)O(2) treatment of SCLC cells (over 15 min) led to phosphorylation of c-Met receptor tyrosine kinase and further upregulated downstream phosphorylation of phospho-AKT, ERK1/2, and paxillin in a dose-dependent manner (125 microM to 500 microM). c-Met is an important target in lung cancer, and the pathways responsible for ROS generation together may provide novel therapeutic intervention.
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PMID:Activation of HGF/c-Met pathway contributes to the reactive oxygen species generation and motility of small cell lung cancer cells. 1732 84

Recent studies have shown that interleukin 6 (IL-6) acts on the cellular proliferation-activating transduction signals during cellular regeneration. Therefore, this study examined the effect of IL-6 on the activation of Na(+)/glucose cotransporters (SGLTs) and its related signaling pathways in primary cultured renal proximal tubule cells (PTCs). IL-6 increased the level of alpha-methyl-d-[(14)C]glucopyranoside (alpha-MG) uptake in time- and dose-dependent manners. IL-6 also increased SGLT1 plus SGLT2 mRNA and protein expression level. The IL-6 receptors (IL-6Ralpha and gp 130) were expressed in PTCs. In addition, genistein and herbimycin A completely blocked the IL-6-induced increases in alpha-MG uptake and the protein expression level of SGLTs. On the other hand, IL-6 increased the level of 5-(and-6)-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate-sensitive cellular reactive oxygen species (ROS), and IL-6-induced increases in alpha-MG uptake and the protein expression level of SGLTs were blocked by ascorbic acid or taurine (antioxidants). IL-6 also increased the phosphorylation of signal transducer and activator of transcription-3 (STAT3), phosphoinositide-3 kinase (PI3K)/Akt, and mitogen-activated protein kinases (MAPKs) in a time-dependent manner. A pretreatment with STAT3 inhibitor LY 294002, an Akt inhibitor, or MAPK inhibitors significantly blocked the IL-6-induced increase in alpha-MG uptake. In addition, IL-6 increased the level of nuclear factor-kappaB (NF-kappaB) phosphorylation. A pretreatment with SN50 or BAY 11-7082 also blocked the IL-6-induced increase in alpha-MG uptake. In conclusion, IL-6 increases the SGLT activity through ROS, and its action in renal PTCs is associated with the STAT3, PI3K/Akt, MAPKs, and NF-kappaB signaling pathways.
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PMID:Interleukin-6 stimulates alpha-MG uptake in renal proximal tubule cells: involvement of STAT3, PI3K/Akt, MAPKs, and NF-kappaB. 1758 28

It has been well appreciated that aldosterone (Aldo) plays a direct profibrotic role in the kidney but the underlying mechanism is unclear. We examined the role of Aldo in epithelial-mesenchymal transition (EMT) both in vitro and in vivo. Exposure of human renal proximal tubular cells to Aldo for 48 h dose dependently induced EMT as evidenced by conversion to the spindle-like morphology, loss of E-cadherin, and de novo expression of alpha-smooth muscle actin (SMA); the effect was noticeable at 50 nM and maximal at 100 nM. The EMT was completely blocked by the selective mineralocorticoid receptor (MR) antagonist eplerenone. Aldo time dependently increased intracellular reactive oxygen species (ROS) production that was detectable at 15 min and peaked (2.3-fold) at 60 min, as assessed by 2',7'-dichlorofluorescin diacetate fluorescence. Aldo-induced oxidative stress and EMT were both abolished by the mitochondrial respiratory chain complex I inhibitor rotenone, but not the NADPH oxidase inhibitor apocynin. Aldo induced phosphorylation of ERK1/2 that was completely blocked by rotenone. Male 129-C57/BL6 mice were treated with deoxycorticosterone acetate (DOCA) salt (subcutaneous implantation of 50 mg of DOCA pellet plus 1% NaCl as drinking fluid) for 3 wk and animals were treated with vehicle or rotenone (600 ppm in diet) for the last week. DOCA salt induced a 2.5-fold increase in alpha-SMA and a 30% reduction of E-cadherin, as assessed by real-time RT-PCR, that were both restricted to renal epithelial cells, as determined by immunohistochemistry. In contrast, DOCA salt-induced changes in alpha-SMA and E-cadherin were completely blocked by treatment with rotenone. These observations suggest that Aldo induces EMT via MR-mediated, mitochondrial-originated, ROS-dependent ERK1/2 activation in renal tubular epithelial cells.
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PMID:Aldosterone induces epithelial-mesenchymal transition via ROS of mitochondrial origin. 1759 22

Aromatase is the key enzyme for estrogen biosynthesis. A distal promoter, PI.4, maintains baseline levels of aromatase in normal breast adipose tissue. In contrast, malignant breast epithelial cells secrete prostaglandin E(2) (PGE(2)), which stimulates aromatase expression via proximal promoters PI.3/PII in a cyclic AMP (cAMP)- and protein kinase C (PKC)-dependent manner in adjacent breast adipose fibroblasts (BAF), leading to increased local concentrations of estrogen. Although an effective treatment for breast cancer, aromatase inhibitors indiscriminately abolish estrogen synthesis in all tissues, causing major side effects. To identify drug targets to selectively block aromatase and estrogen production in breast cancer, we investigated PGE(2)-stimulated signaling pathways essential for aromatase induction downstream of cAMP and PKC in human BAFs. Here, we show that PGE(2) or its surrogate hormonal mixture dibutyryl cAMP (Bt(2)cAMP) + phorbol diacetate (PDA) stimulated the p38, c-jun NH(2)-terminal kinase (JNK)-1, and extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase pathways. Inhibition or small interfering RNA-mediated knockdown of p38 or JNK1, but not ERK, inhibited PGE(2)- or Bt(2)cAMP + PDA-induced aromatase activity and expression via PI.3/PII. Conversely, overexpression of wild-type p38alpha or JNK1 enhanced PGE(2)-stimulated aromatase expression via PII. PGE(2) or Bt(2)cAMP + PDA stimulated c-Jun and activating transcription factor-2 (ATF2) phosphorylation and binding to the PI.3/PII region. Specific activation of protein kinase A (PKA) or EPAC with cAMP analogues stimulated p38 and JNK1; however, only PKA-activating cAMP analogues induced aromatase expression. The PKC activator PDA effectively stimulated p38 and JNK1 phosphorylation but not aromatase expression. Taken together, PGE(2) activation of p38 and JNK1 via PKA and PKC is necessary for aromatase induction in BAFs, and p38 and JNK1 are potential new drug targets for tissue-specific ablation of aromatase expression in breast cancer.
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PMID:Prostaglandin E(2) induces breast cancer related aromatase promoters via activation of p38 and c-Jun NH(2)-terminal kinase in adipose fibroblasts. 1787 34

Trophic deprivation contributes to astrocyte damage that occurs in acute and chronic neurodegenerative disorders. Unraveling the underlying mechanisms may pave way to novel cytoprotective strategies. Cultured mouse astrocytes responded to trophic deprivation with a large and transient increase in the expression of p21(ras), which was secondary to an enhanced formation of reactive oxygen species (ROS) detected by cytofluorimetric analysis after preloading with 2',7'-dichlorofluorescein diacetate. The increase in p21(ras) levels was largely attenuated by the reducing agent, N-acetylcysteine, which was proven to reduce ROS formation in astrocytes subjected to serum deprivation. We extended the analysis to the Ha-Ras isoform, which has been implicated in mechanisms of cytotoxicity. We found that serum deprivation enhanced the expression and activity of Ha-Ras without changing Ha-Ras mRNA levels. The increase in Ha-Ras levels was sensitive to the protein synthesis inhibitor, cycloheximide, suggesting that serum deprivation increases translation of preformed Ha-Ras mRNA. The late decline in Ha-Ras levels observed after 60 min was prevented by the proteasome inhibitor, MG132, as well as by the selective mitogen-activated protein kinase (MAPK) inhibitor, PD98059. Serum deprivation led to the activation of the MAPK pathway in cultured astrocytes, as shown by an increase in phosphorylated extracellular signal-regulated kinase 1/2 levels after 5 and 30 min. Finally, using the siRNA technology, we found that an acute knock-down of Ha-Ras was protective against astrocyte damage induced by serum deprivation. We conclude that cultured astrocytes respond to trophic deprivation with an increased expression in Ha-Ras, which is limited by the concomitant activation of the MAPK pathway, but is nevertheless involved in the pathophysiology of cell damage.
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PMID:Enhanced expression of Harvey ras induced by serum deprivation in cultured astrocytes. 1841 May 9

Previous investigations have revealed that dental monomers could affect intracellular pathways leading to cell survival or cell death. Mitogen-activated protein kinase (MAPK) and protein kinase B (AKT) might mediate cell responses as well as cell survival and apoptosis. The purpose of this study was to evaluate the effects of 2-hydroxyethyl methacrylate (HEMA) on the ERK1/2 and AKT pathways in human primary pulp fibroblasts (HPCs). HPCs were treated with various concentrations of HEMA, after which viability and reactive oxygen species levels were determined by flow cytometry with Annexin V-PI staining and 2,7-dichlorofluorescine diacetate, respectively. Whole-cell extracts were immunoblotted with anti-P-Akt or anti-P-ERK1/2. Cell viability decreased in a dose-dependent manner after HEMA exposure, showing a significant decrease with 10 mmol/L HEMA (p < .05). HEMA treatment resulted in a 4-fold increase in reactive oxygen species formation (p < .05). A short HEMA exposure (30-90 minutes) increased ERK1/2 phosphorylation, whereas a decrease in the AKT phosphorylation was observed. Selective inhibitors of the ERK (PD98059) and AKT (LY294002) pathways amplified HPC cell damage after HEMA exposure. Our findings demonstrated that HEMA exposure modulates the ERK and AKT pathways in different manners, and that in turn, they function in parallel to mediate pro-survival signaling in pulp cells subjected to HEMA cytotoxicity.
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PMID:Effect of 2-hydroxyethyl methacrylate on human pulp cell survival pathways ERK and AKT. 1849 89

1. Peroxisome proliferator-activated receptor (PPAR)-gamma agonists have been demonstrated to exert protective effects against homocysteine (Hcy)-induced pathogenesis. However, the effects of PPAR-gamma agonists on Hcy-induced migration are unknown. In the present study, we examined the effect of pioglitazone on the migration of vascular smooth muscle cells (VSMC) induced by Hcy and the possible mechanism involved. 2. Vascular smooth muscle cells were isolated from the thoracic aortas of male Sprague-Dawley rats. The migration of VSMC was examined using a transwell technique. The generation of intracellular reactive oxygen species (ROS) was measured using the ROS-sensitive fluoroprobe 2',7'-dichlorodihydrofluorescein diacetate. The activity of NAD(P)H oxidase was assessed by lucigenin enhanced chemiluminescence. Activation of p38 mitogen-activated protein kinase (MAPK) was determined by western blotting. 3. The results showed that pioglitazone dose-dependently inhibited the migration of VSMC induced by Hcy. This was not reversed by the PPAR-gamma antagonist GW9662. In addition, pretreatment with the NAD(P)H oxidase inhibitor diphenylene iodonium (DPI), the free radical scavenger N-acetylcysteine and the p38 MAPK inhibitor SB202190 blocked Hcy-induced VSMC migration. Furthermore, we observed that pioglitazone suppressed Hcy-induced intracellular ROS production; similar effects were observed with DPI and NAC. Pioglitazone attenuated Hcy-induced activation of NAD(P)H oxidase. Moreover, pioglitazone blocked Hcy-induced p38 MAPK phosphorylation; similar effects were observed for DPI, NAC and SB202190. 4. The data demonstrate that pioglitazone inhibits Hcy-induced VSMC migration that is independent of PPAR-gamma. Furthermore, part of the biological effect of pioglitazone involves a decrease in the levels of NAD(P)H oxidase derived-ROS and p38 MAPK activation.
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PMID:Pioglitazone inhibits homocysteine-induced migration of vascular smooth muscle cells through a peroxisome proliferator-activated receptor gamma-independent mechanism. 1875 64

Tumor cells are known to produce larger amounts of reactive oxygen species (ROS) than normal cells. Although numerous reports have indicated the importance of ROS in urokinase plasminogen activator (uPA) production, the precise mechanisms remain controversial. In our study, we investigated the effect of ROS on uPA generation in human hepatoma cells, HepG2 and Hep 3B. We determined the effects of hepatocyte growth factor (HGF) on the regulation of ROS, which resulted in suppression of ROS production, as measured with the fluorescent probe, 2'-7'-dichlorofluorescein diacetate. The role of HGF in modulating ROS production, particularly that regulated by Rac-1, was determined. HGF suppressed the increment in Rac-1-regulated ROS in both cell lines. Treatment with 200 micrometer of H(2)O(2) showed a 1.6-2.1 fold increment in HGF, but a little increment occurred at 500 micrometer of H(2)O(2). It looks no dose dependent manner. Combined treatment with H(2)O(2) and HGF, resulted in a slightly increased production of HGF compared to no treatment (control). Also, H(2)O(2) upregulated uPA expression in both hepatoma cell lines. To identify the downstream pathways regulated by ROS, we treated cells with PD 98059, an MEK inhibitor, and SB 203580, a p38 inhibitor, after treatment with H(2)O(2), and showed negative control between ERK and p38 kinase activities for uPA regulation. We found that HGF modulate Rac-1-regulated ROS production through activation of Akt and ROS regulates uPA production via MAP kinase, which provides a novel clue to clarify the mechanism underlying hepatoma progression.
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PMID:Reactive oxygen species regulate the generation of urokinase plasminogen activator in human hepatoma cells via MAPK pathways after treatment with hepatocyte growth factor. 1929 37


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