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)

Cell growth arrest is an important mechanism in maintaining genomic stability and integrity in response to environmental stress. Using the human lung alveolar epithelial cancer cell line A549, we investigated the role of reactive oxygen species (ROS), extracellular signal-regulated protein kinase (ERK), and p38 protein kinase in vanadate-induced cell growth arrest. Exposure of cells to vanadate led to cell growth arrest at the G(2)/M phase and caused upregulation of p21 and phospho-cdc2 and degradation of cdc25C in a time- and dose-dependent manner. Vanadate stimulated mitogen-activated protein kinases (MAPKs) family members, as determined by the phosphorylation of ERK and p38. PD98059, an inhibitor of ERK, and SB202190, an inhibitor of p38, inhibited vanadate-induced cell growth arrest, upregulation of p21 and cdc2, and degradation of cdc25C. In addition to hydroxyl radical ((*)OH) formation, cellular reduction of vanadate generated superoxide radical (O(2)(*)(-)) and hydrogen peroxide (H(2)O(2)), as determined by confocal microscopy using specific dyes. Generation of O(2)(*)(-) and H(2)O(2) was inhibited by specific antioxidant enzymes, superoxide dismutase (SOD) and catalase, respectively. ROS activate ERK and p38, which in turn upregulate p21 and cdc2 and cause degradation of cdc25C, leading to cell growth arrest at the G(2)/M phase. Specific ROS affect different MAPK family members and cell growth regulatory proteins with different potencies.
 ...
PMID:Role of reactive oxygen species and MAPKs in vanadate-induced G(2)/M phase arrest. 1272 21

Reactive oxygen species (ROS) play a role in cardiovascular diseases such as heart failure and hypertension. Furthermore, increasing evidence has accumulated suggesting that ROS can also be formed subsequent to the stimulation of various receptors, thus functioning as second messengers. The objective of the present study was to elucidate the role of intracellular-generated ROS in the inotropic and chronotropic effects of the alpha1- and beta-adrenoceptor and the ET-receptor stimulation in isolated rat atria. In addition, we investigated whether the MAPKerk pathway is involved in the ROS-provoked rise of contractile force. For this purpose hydrogen peroxide was applied, which is known to serve several endogenous functions as a second messenger. Moreover, hydrogen peroxide readily crosses cell membranes, which thus allows to mimic the intracellular formation. Preincubation of atria with EUK 8 (400 microM), a cell permeable superoxide dismutase- and catalase-mimetic, reduced the positive inotropic effect upon alpha1-adrenoceptor and ET-receptor stimulation. The responsiveness to beta-adrenoceptor stimulation remained unaffected by this pretreatment. The chronotropic effects were not altered by preincubation with EUK 8. In contrast to the MAPK(p38) inhibitor SB203580 (2 and 10 microM), the two MKKmek inhibitors PD98059 (30 and 100 microM) and U0126 (10 microM) significantly attenuated the positive inotropic response to hydrogen peroxide in isolated rat left atria. In addition, inhibition of the Na+/H+ exchange (NHE) by cariporide (1 microM) counteracted ROS-provoked increase of contractile force. From the present study we conclude that the inotropic responses to alpha1-adrenoceptor and ET-receptor stimulation are, at least partially, caused by intracellular-formed ROS, that subsequently may activate the MAPKerk pathway and the NHE.
 ...
PMID:The influence of endogenously generated reactive oxygen species on the inotropic and chronotropic effects of adrenoceptor and ET-receptor stimulation. 1273 26

The use of botanical supplements has received immense interest in recent years to protect human skin from adverse biological effects of solar ultraviolet (UV) radiation. The polyphenols from green tea are one of them and have been shown to prevent photocarcinogenesis in animal models but their mechanism of photoprotection is not well understood. To determine the mechanism of photoprotection in in vivo mouse model, topical treatment of polyphenols from green tea (GTP) or its most chemopreventive constituent (-)-epigallocatechin-3-gallate (EGCG) (1 mg/cm(2) skin area) in hydrophilic ointment USP before single (180 mJ/cm(2)) or multiple UVB exposures (180 mJ/cm(2), daily for 10 days) resulted in significant prevention of UVB-induced depletion of antioxidant enzymes such as glutathione peroxidase (78-100%, P < 0.005-0.001), catalase (51-92%, P < 0.001) and glutathione level (87-100%, P < 0.005). Treatment of EGCG or GTP also inhibited UVB-induced oxidative stress when measured in terms of lipid peroxidation (76-95%, P < 0.001), and protein oxidation (67-75%, P > 0.001). Further, to delineate the inhibition of UVB-induced oxidative stress with cell signaling pathways, treatment of EGCG to mouse skin resulted in marked inhibition of a single UVB irradiation-induced phosphorylation of ERK1/2 (16-95%), JNK (46-100%) and p38 (100%) proteins of MAPK family in a time-dependent manner. Identical photoprotective effects of EGCG or GTP were also observed against multiple UVB irradiation-induced phosphorylation of the proteins of MAPK family in vivo mouse skin. Photoprotective efficacy of GTP given in drinking water (d.w.) (0.2%, w/v) was also determined and compared with that of topical treatment of EGCG and GTP. Treatment of GTP in d.w. also significantly prevented single or multiple UVB irradiation-induced depletion of antioxidant enzymes (44-61%, P < 0.01-0.001), oxidative stress (33-71%, P < 0.01) and phosphorylation of ERK1/2, JNK and p38 proteins of MAPK family but the photoprotective efficacy was comparatively less than that of topical treatments of EGCG and GTP. Lesser photoprotective efficacy of GTP in d.w. in comparison with topical application may be due to its less bioavailability in skin target cells. Together, for the first time a cream based formulation of green tea polyphenols was tested in this study to explore the possibility of its use for the humans, and the data obtained from this in vivo study further suggest that GTP could be useful in attenuation of solar UVB light-induced oxidative stress-mediated and MAPK-caused skin disorders in humans.
 ...
PMID:Treatment of green tea polyphenols in hydrophilic cream prevents UVB-induced oxidation of lipids and proteins, depletion of antioxidant enzymes and phosphorylation of MAPK proteins in SKH-1 hairless mouse skin. 2972 76

Oxidative stress has been implicated as a mechanism for a variety of forms of liver injury. Although reactive oxygen species (ROS) may damage cellular macromolecules directly, oxidant-induced cell death may result from redox effects on signal transduction pathways. To understand the mechanisms of hepatocyte death from oxidative stress, the functions of the mitogen-activated protein kinases (MAPKs) were determined during oxidant-induced hepatocyte injury from menadione. Low, nontoxic, and high toxic concentrations of the superoxide generator menadione were established in the RALA255-10G rat hepatocyte cell line. Death from menadione was blocked by catalase and ebselen, indicating that death was secondary to oxidant generation and not arylation. Treatment with a nontoxic menadione concentration resulted in a brief activation of extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK). In contrast, treatment with a toxic menadione concentration induced a prolonged activation of both ERK and JNK. Chemical inhibition of ERK function sensitized RALA hepatocytes to death from previously nontoxic menadione concentrations in association with sustained JNK activation. Adenoviral expression of a dominant-negative protein for c-Jun, a downstream substrate for JNK, blocked death from menadione. The pro-apoptotic effect of c-Jun was not mediated through the mitochondrial death pathway. In conclusion, RALA hepatocyte resistance to oxidant-induced death from menadione is dependent on ERK, whereas cell death is mediated by AP-1 activation. These findings identify signaling pathways that may be therapeutic targets in the prevention or treatment of oxidant-induced liver injury.
 ...
PMID:Oxidant-induced hepatocyte injury from menadione is regulated by ERK and AP-1 signaling. 1277 20

The inducible form of heme oxygenase (HO-1) is increased during oxidative injury, and this may be an important defense mechanism against such injury. Cytochrome P450 2E1 (CYP2E1) generates reactive oxygen species and promotes lipid peroxidation. In this study induction of HO-1 by CYP2E1 and the possible role of mitogen-activated protein kinase (MAPK) in this process were evaluated. HO-1 induction was observed in the livers of chronic alcohol-fed mice or pyrazole-treated rats, conditions known to elevate CYP2E1 levels. Increased levels of HO-1 were observed in HepG2 cells overexpressing CYP2E1 (E47 cells) compared with control HepG2 cells or HepG2 cells expressing CYP3A4. Expression of CYP2E1 in HepG2 cells transcriptionally activated the HO-1 gene, increasing HO-1 mRNA and protein expression and activity of a HO-1 reporter construct. CYP2E1 inhibitors and catalase blocked the increased production of reactive oxygen species as well as HO-1 induction. Increasing oxidative stress by the addition of arachidonic acid or depletion of glutathione further increased HO-1 induction. The phosphorylated form of ERK MAPK but not that of p38 or JNK MAPK was increased in E47 cells compared with the control C34 HepG2 cells. PD98059, a specific inhibitor of ERK MAPK, blocked the activity of a HO-1 reporter in E47 cells but not in C34 cells. These results suggest that increased CYP2E1 activity leads to induction of the HO-1 gene, and the ERK MAPK pathway is important in mediating this process. This induction may serve as an adaptive mechanism to protect the E47 cells against the CYP2E1-dependent oxidative stress.
 ...
PMID:Increased expression of cytochrome P450 2E1 induces heme oxygenase-1 through ERK MAPK pathway. 1277 98

Excessive generation of reactive oxygen species (ROS) in the central nervous system (CNS) is a leading cause of neuronal injury. Despite yet unknown mechanisms, oxidant compounds such as H(2)O(2) have been shown to stimulate the release of arachidonic acid (AA) in a number of cell systems. In this study, H(2)O(2) and menadione, a compound known to release H(2)O(2) intracellularly, were used to examine the phospholipases A(2) (PLA(2)) responsible for AA release from primary murine astrocytes. Both H(2)O(2) and menadione dose-dependently stimulated AA release, and the release mediated by H(2)O(2) was completely inhibited by catalase. H(2)O(2) also stimulated phosphorylation of extracellular signal-regulated kinases (ERK1/2) and cytosolic phospholipase A(2) (cPLA(2)). However, complete inhibition of cPLA(2) phosphorylation by U0126, an inhibitor for mitogen-activated protein kinase kinase (MEK) and GF109203x, a nonselective PKC inhibitor preferring the conventional and novel isoforms, only reduced H(2)O(2)-stimulated AA release by 50%. MAFP, a selective, active, site-directed, irreversible inhibitor of both cPLA(2) and the Ca(2+)-independent iPLA(2), nearly completely inhibited H(2)O(2)-mediated AA release; but, HELSS, a potent irreversible inhibitor of iPLA(2), only inhibited H(2)O(2)-mediated AA release by 40%. Along with the observation that H(2)O(2)-mediated AA release was only partially inhibited upon chelating intracellular Ca(2+) by BAPTA, these results indicate the involvement of both cPLA(2) and iPLA(2) in H(2)O(2)-mediated AA release in murine astrocytes.
 ...
PMID:Oxidant-mediated AA release from astrocytes involves cPLA(2) and iPLA(2). 1278 73

Mistletoe lectin-II, a major component of Korean mistletoe (Viscum album var. coloratum) induces apoptotic death in cancer cells. In this study, we demonstrated that lectin-II induced the generation of pro-oxidants and thus resulted in the apoptotic death of human myeloleukemic U937 cells. We observed that lectin-II-induced apoptotic death was inhibited by antioxidants including reduced glutathione (GSH), N-acetylcysteine (NAC), ebselen, mnTBP, catalase and pyrrolidine dithiocarbamate (PDTC). GSH and NAC also abolished the apoptotic DNA ladder pattern fragmentation of U937 cells after lectin-II stimulation. Obviously, lectin-II treatment of cells resulted in a remarkable generation of intracellular hydrogen peroxide (H2O2) as an early event, which was monitored fluorimetrically using scopoletin-horse radish peroxidase (HRP) assay and peroxide-sensitive fluorescent probe, DCF-DA. In addition, antioxidants inhibited the activation of c-Jun N-terminal kinase (JNK)/stress-activated protein kinase (SAPK) as well as cytosolic release of cytochrome c by mistletoe lectin-II. Moreover, lectin-II-induced activation of caspase-9 and 3-like protease and cleavage of poly(ADP-ribose) polymerase (PARP) were inhibited by pretreatment of cells with thiol antioxidants, GSH and NAC. Taken together, these results suggest that Korean mistletoe lectin-II is a strong inducer of pro-oxidant generation such as H2O2, which mediates the JNK/SAPK activation, cytochrome c release, activation of caspase-9 and caspase 3-like protease, and PARP cleavage in human myeloleukemic U937 cells.
 ...
PMID:Involvement of hydrogen peroxide in mistletoe lectin-II-induced apoptosis of myeloleukemic U937 cells. 1285 Feb 39

Apoptosis is an active form of cell death that is initiated by a variety of stimuli, including reactive oxygen species (ROS) and ultraviolet (UV) radiation. Previously, it has been reported that UVB-irradiation of keratinocytes leads to intracellular generation of hydrogen peroxide (H2O2) and that antioxidants can inhibit ROS-induced apoptosis. Although both UVB-irradiation and H2O2-incubation led to increased intracellular H2O2 levels, the antioxidants catalase and glutathione monoester (GME), inhibited apoptosis only when induced by H2O2, not by UVB. Furthermore, extracellular signal-regulated kinase (ERK), a prominent member of the mitogen-activated protein kinase (MAPK) family, was found to be activated by treatment with both UVB and H2O2. Inhibition of ERK phosphorylation by pre-treatment with PD98059 resulted in enhanced apoptosis after H2O2-exposure. However,no significant difference of apoptosis was observed between cells with and without inhibitor pre-treatment upon UVB-irradiation. DNA damage in the form of cyclobutane pyrimidine dimers was observed after exposure to UVB, but no photoproducts were found in H2O2-treated cells. These results suggest a ROS-independent pathway of UVB-induced apoptosis. Although UVB-irradiation causes moderate increase in H2O2, the generation of H2O2 does not contribute to the induction of apoptosis. Moreover, activation of ERK only blocks H2O2-dependent apoptosis but has no impact on UVB-induced apoptosis.
 ...
PMID:The role of H2O2 as a mediator of UVB-induced apoptosis in keratinocytes. 1286 92

Anthocyanidins are the aglycon nucleuses of anthocyanins, which are reddish pigments widely spread in colored fruits and vegetables. To investigate their anti-cancer effect, induction of apoptosis was tested in human promyelocytic leukemia cells (HL-60), which is a valid model for testing antileukemic or general antitumoral compounds. Of six anthocyanidins representing the aglycons of most of anthocyanins, only those with an ortho-dihydroxyphenyl structure on the B-ring induce apoptosis, suggesting that the ortho-dihydroxyphenyl structure of anthocyanidins may contribute to the induction of apoptosis. Delphinidin, the most potent inducer, causes apoptosis in a time- and dose-dependent manner. The efficacious induction of apoptosis was observed at 100 micro M for 6 h. Concomitant with the apoptosis, delphinidin stimulates JNK pathway activation including JNK phosphorylation and c-jun gene expression, and activates caspase-3. Antioxidants including N-acetyl-L-cysteine (NAC) and catalase effectively block delphinidin-induced JNK phosphorylation, caspase-3 activation, and DNA fragmentation. Moreover, anthocyanidins directly cause HL-60 cells to generate intracellular hydrogen peroxide. Thus, anthocyanidins may trigger an apoptotic death program through an oxidative stress-involved JNK signaling pathway. The induction of apoptosis by anthocyanins may be the pivotal mechanism by which its chemopreventive action against cancer is based.
 ...
PMID:Anthocyanidins induce apoptosis in human promyelocytic leukemia cells: structure-activity relationship and mechanisms involved. 1288 7

Both epidemiological and experimental studies indicate that ethanol is a tumor promoter and may promote metastasis of breast cancer. However, the molecular mechanisms underlying ethanol-mediated tumor promotion remain unknown. Overexpression of ErbB proteins in breast cancer patients is generally associated with poor prognosis. The ErbB proteins are a family of receptor kinases that include four closely related members: epidermal growth factor receptor (EGFR/ErbB1), ErbB2/neu, ErbB3, and ErbB4. Particularly, ErbB2 plays a pivotal role in ErbB-mediated activities. Here we demonstrated that amplification of ErbB2 expression sensitized a specific cellular response to ethanol. Human breast cancer cells or mammary epithelial cells with a high expression of ErbB2 exhibited an enhanced response to ethanol-stimulated cell invasion in vitro. Ethanol also stimulated cell proliferation; however, this stimulation was independent of ErbB2 levels. Ethanol triggered divergent intracellular signaling among cells expressing different ErbB2 levels. In the cells overexpressing ErbB2, ethanol was more effective in the activation of c-Jun NH2 terminal protein kinases (JNKs) and p38 mitogen-activated protein kinase (p38 MAPK) as well as the induction of reactive oxygen species (ROS) than the cells with normal ErbB2 expression. Blockage of either JNKs or p38 MAPK activation eliminated ethanol-mediated cell invasion. In contrast, the reduction of hydrogen peroxide concentration by catalase exposure had little effect on ethanol-induced cell invasion. These results indicated that ethanol-induced cell invasion was primarily mediated by JNKs and p38 MAPK, whereas the involvement of ROS formation might be minimal. Our study suggests that overexpression of ErbB2 may augment ethanol-elicited signaling and promote ethanol-stimulated tumor metastasis.
 ...
PMID:Overexpression of ErbB2 enhances ethanol-stimulated intracellular signaling and invasion of human mammary epithelial and breast cancer cells in vitro. 1291 29


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>