Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.12.2 (MEK)
 18,161 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Endothelial cell migration is critical for proper blood vessel development. Signals from growth factors and matrix proteins are integrated through focal adhesion proteins to alter cell migration. Hydrogen peroxide-inducible clone 5 (Hic-5), a paxillin family member, is enriched in the focal adhesions in bovine pulmonary artery endothelial (BPAE) cells, which migrate to lysophosphatidic acid (LPA) on denatured collagen. In this study, we investigate the role of Hic-5 in LPA-stimulated endothelial cell migration. LPA recruits Hic-5 to the focal adhesions and to the pseudopodia in BPAE cells plated on collagen, suggesting that recruitment of Hic-5 to focal adhesions is associated with endothelial cell migration. Knockdown of endogenous Hic-5 significantly decreases migration toward LPA, confirming involvement of Hic-5 in migration. To address the role of Hic-5 in endothelial cell migration, we exogenously expressed wild-type (WT) Hic-5 and green fluorescent protein Hic-5 C369A/C372A (LIM3 mutant) constructs in BPAE cells. WT Hic-5 expression increases chemotaxis of BPAE cells to LPA, whereas migration toward LPA of the green fluorescent protein Hic-5 C369A/C372A-expressing cells is similar to that shown in vector control cells. Additionally, ERK phosphorylation is enhanced in the presence of LPA in WT Hic-5 cells. A pharmacological inhibitor of MEK activity inhibits LPA-stimulated WT Hic-5 cell migration and ERK phosphorylation, suggesting Hic-5 enhances migration via MEK activation of ERK. Together, these studies indicate that Hic-5, a focal adhesion protein in endothelial cells, is recruited to the pseudopodia in the presence of LPA and enhances migration.
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PMID:Hic-5 promotes endothelial cell migration to lysophosphatidic acid. 1733 98

Prdx6, a unique member of the peroxiredoxin family of antioxidants, is highly expressed in liver and protects cells from oxidative damage by reducing H2O2 and various lipid peroxides. We investigated the transcriptional regulation of Prdx6 in the H2.35 mouse hepatocyte cell line and sought to determine the mechanism of basal and induced expression. We found that Prdx6 expression is down-regulated upon serum deprivation and subsequently induced in a time-dependent manner in response to KGF, TNF-alpha, dexamethasone, and H2O2. Inhibitors of both PKC and MEK largely prevented Prdx6 induction by KGF and, to a lesser extent, TNF-alpha. Interestingly, inhibition of NF-kappaB led to a marked increase in Prdx6 regulation in the absence or presence of inducers, suggesting a normal role for NF-kappaB in Prdx6 suppression. Using reporter constructs from the mouse gene, we found that the first 160 bp of the proximal promoter was sufficient for low levels of expression, and expression increased sixfold with 1200 bp of the proximal promoter. These regions were not, however, sufficient to mediate up-regulation by the known Prdx6 inducers in our system. Together, these data support multiple pathways of Prdx6 regulation and reveal important promoter regions that mediate its transcriptional regulation.
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PMID:Investigating transcriptional regulation of Prdx6 in mouse liver cells. 1738 7

Oxidized low density lipoproteins (oxLDL), macrophages and T-lymphocytes are present in atherosclerotic lesions. We and others have shown that oxLDL is cytotoxic for macrophages, endothelial, smooth muscle and activated T-lymphocytes and induce apoptosis. Here we demonstrate that (i) oxidized LDL (oxLDL), oxidized VLDL (oxVLDL) and hydrogen peroxide (H2O2) induce apoptosis in human T-lymphocytes and (ii) mitogen-activated protein kinases are involved in this process. Apoptosis was monitored by immunofluorescence microscopy and flow cytometry for annexin V binding, Apo 2.7 expression, the TUNEL reaction and caspase 3 activity. In the presence of oxLDL (100 microg/ml), oxVLDL (50 microg/ml) and H2O2 (5 mM), the fraction of apoptotic cells increased within 6 hours to more than 70%. Preincubation of lymphocytes with the MAPKK inhibitor PD-98059 and the p38MAPK inhibitor SB-203580 almost completely abolished these effects. Furthermore, oxLDL and H2O2 but not native LDL strongly enhanced phosphorylation of JNK, p38MAPK and p42/44MAPK. The results suggest that in the resting lymphocyte apoptosis triggered by oxidized lipoproteins and oxidative stress depends on the activation of p44/42MAPK and p38MAPK cascades.
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PMID:Oxidized low density lipoproteins induce apoptosis in human lymphocytes: involvement of mitogen-activated protein kinases. 1769 85

3-methyl-6-chloro-7,8-hydroxy-1-(3-methylphenyl)-2,3,4,5-tetrahydro-1H-3-benzazepine (SKF83959), a selective agonist for the putative phosphatidylinositol (PI)-linked dopamine receptor (DAR), has been shown to possess potent anti-Parkinson disease effects but produces less dyskinesia and motor fluctuation that are frequently observed in Parkinson disease drug therapies. The present study was designed to detect the neuroprotection of SKF83959 and its potential mechanism for the effect in cultured rat cortical cells. The presence of SKF83959 with a dose range of 0.1-30 micromol/L improved H2O2-reduced cell viability in a dose-dependent manner. The anti-apoptotic action of SKF83959 was partially abolished by pre-application of the D1 antagonist SCH23390 (30 micromol/L) and the PI 3-kinase (PI 3-K) inhibitor LY294002 but not by the MEK1/2 inhibitor PD98059 (30 micromol/L). Moreover, SKF83959 treatment significantly inhibited H2O2-activated glycogen synthase kinase-3beta (GSK-3beta) which was associated with the drug's neuroprotective effect, but this inhibition was attenuated by SCH23390 and a selective PI 3-K inhibitor. Moreover, the application of either SKF83959 or a pharmacological inhibitor of GSK-3beta attenuated the inhibition by H2O2 on the expression of inducible NO synthase and production of NO. This indicates that D1-like receptor, presumably PI-linked D1 receptor, -mediated alteration of PI 3-K/Akt/GSK-3beta pathway is involved in the neuroprotection by SKF83959. In addition, SKF83959 also effectively decreased the level of the lipid peroxidation and increased the activity of GSH-peroxidase altered by H2O2. These results suggest that SKF83959 exerts its neuroprotective effect through both receptor-dependent and independent mechanisms: Inhibition of GSK-3beta and consequently increasing the expression of inducible NO synthase via putative PI-linked DAR; and its anti-oxidative activity which is independent of DAR.
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PMID:Neuroprotective effects of atypical D1 receptor agonist SKF83959 are mediated via D1 receptor-dependent inhibition of glycogen synthase kinase-3 beta and a receptor-independent anti-oxidative action. 1800 41

Despite of the increasing evidence that oxidative stress may induce non-apoptotic cell death or autophagic cell death, the mechanism of this process is unclear. Here, we report a role and a down-stream molecular event of Atg5 during oxidative stress-induced cell death. Compared to wild type (WT) cells, Atg5-deficient mouse embryo fibroblasts (Atg5-/- MEFs) and Atg5 knockdown HT22 neuronal cells were more resistant to cell death induced by H2O2. On the contrary, Atg5-/- MEFs were as sensitive to tumor necrosis factor (TNF)-alpha and cycloheximide as WT cells, and were more sensitive to cell death triggered by amino acid-deprivation than WT MEFs. Treatment with H2O2 induced the recruitment of a GFP-LC3 fusion protein and conversion of LC3 I to LC3 II, correlated with the extent of autophagosome formation in WT cells, but much less in Atg5-deficient cells. Among stress kinases, ERK1/2 was markedly activated in Atg5-/- MEFs and Atg5 knockdown HT22 and SH-SY5Y neuronal cells. The inhibition of ERK1/2 by MEK1 inhibitor (PD98059) or dominant negative ERK2 enhanced the susceptibility of Atg5-/- MEFs to H2O2-induced cell death. Further, reconstitution of Atg5 sensitized Atg5-/- MEFs to H2O2 and suppressed the activation of ERK1/2. These results suggest that the inhibitory effect of Atg5 deficiency on cell death is attributable by the compensatory activation of ERK1/2 in Atg5-/- MEFs during oxidative stress-induced cell death.
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PMID:Compensatory activation of ERK1/2 in Atg5-deficient mouse embryo fibroblasts suppresses oxidative stress-induced cell death. 1819 69

Although tubular necrosis in acute renal failure is associated with excessive production of reactive oxygen species (ROS), such as hydrogen peroxide (H2O2), the mechanism of ROS-induced cell necrosis remains poorly understood. In this study, we examined the role of the extracellular signaling-regulated kinase (ERK) pathway in H2O2-induced necrosis of renal proximal tubular cells (RPTC) in primary culture. Exposure of 60 to 70% confluent RPTC to 1 mM H2O2 for 3 h resulted in 44% necrotic cell death, as measured by trypan blue uptake, and inactivation of mitogen-activated protein kinase kinase (MEK), the upstream activator of ERK, by either 1,4-diamino-2,3-dicyano-1,4-bis[2-aminophenylthio]butadiene (U0126) or 2-(2'-amino-3'-methoxyphenyl)-oxanaphthalen-4-one (PD98059) or overexpression of dominant-negative mutant of MEK1, inhibited cell death. In contrast, overexpression of active MEK1 enhanced H2O2-induced cell death. H2O2 treatment led to the loss of mitochondrial membrane potential (MMP) in RPTC, which was decreased by U0126 and PD98059. Furthermore, inhibition of the MEK/ERK pathway decreased oxidant-mediated ERK1/2 activation and mitochondrial swelling in isolated renal cortex mitochondria. However, treatment with cyclosporin A (CsA), a mitochondrial permeability transition blocker, did not suppress RPTC necrotic cell death, loss of MMP, and mitochondrial swelling. We suggest that ERK is a critical mediator of mitochondrial dysfunction and necrotic cell death of renal epithelial cells following oxidant injury. Oxidant-induced necrotic cell death was mediated by a CsA-insensitive loss of MMP that is regulated by the ERK pathway.
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PMID:Extracellular signal-regulated kinase activation mediates mitochondrial dysfunction and necrosis induced by hydrogen peroxide in renal proximal tubular cells. 1833 70

Phosphorelay signaling of environmental stimuli by two-component systems is prevailing in bacteria and also utilized by fungi and plants. In the fission yeast Schizosaccharomyces pombe, peroxide stress signals are transmitted from the Mak2/3 sensor kinases to the Mpr1 histidine-containing phosphotransfer (HPt) protein and finally to the Mcs4 response regulator, which activates a MAP kinase cascade. Here we show that, unexpectedly, the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) physically associates with the Mcs4 response regulator and stress-responsive MAP kinase kinase kinases (MAPKKKs). In response to H2O2 stress, Cys-152 of the Tdh1 GAPDH is transiently oxidized, which enhances the association of Tdh1 with Mcs4. Furthermore, Tdh1 is essential for the interaction between the Mpr1 HPt protein and the Mcs4 response regulator and thus for phosphorelay signaling. These results demonstrate that the glycolytic enzyme GAPDH plays an essential role in the phosphorelay signaling, where its redox-sensitive cysteine residue may provide additional input signals.
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PMID:Glycolytic enzyme GAPDH promotes peroxide stress signaling through multistep phosphorelay to a MAPK cascade. 1840 31

The neurotrophic actions of pituitary adenylate cyclase-activating polypeptide (PACAP)-38 and leukemia inhibitory factor (LIF) were investigated in human neuroblastoma SH-SY5Y cells. Effects on differentiation were assessed through monitoring morphological changes and Western blot analysis of the expression of neuronal marker proteins. In contrast to PACAP-38, which induced a 5.5-fold increase in the number of neurite-bearing cells, LIF had no significant effect on cell morphology compared to control cells over the 4-day time course. Cells co-treated with PACAP-38+LIF showed a similar increase in neurite-bearing cells compared to those treated with PACAP-38 alone. Cell morphology was similar for PACAP-38-treated and PACAP-38+LIF-co-treated cells, with the formation of bipolar neuron-like cells with long thin neurites, topped by growth cone-like structures and varicosities. SH-SY5Y cells express tyrosine hydroxylase (TH) but only low levels of the neuronal marker proteins: Bcl-2, GAP-43 and choline acetyltransferase (ChAT). Treatment of cells with PACAP-38 induced the expression of Bcl-2, GAP-43, and ChAT but did not appear to alter the expression of TH. LIF failed to induce the expression of GAP-43 and had little effect on the expression of TH, but did induce the expression of Bcl-2 and upregulated the expression of ChAT. Co-treatment with LIF had no effect on PACAP-38-induced expression of Bcl-2, GAP-43, and ChAT. Cells differentiated for 4 days with PACAP-38 or treated with LIF also displayed increased resistance to hypoxic conditions and to treatment with H2O2 and TNFalpha. The increased resistance to hypoxic conditions for PACAP-differentiated cells was blocked by the p38 MAP kinase inhibitor, SB203580, but not by the MEK1 inhibitor, PD98059. Additionally, cell proliferation assays show that LIF, but not PACAP-38, stimulates proliferation of SH-SY5Y cells, and this observed increase by LIF is not attenuated by co-treatment with PACAP. Further investigation of the intracellular signaling pathways mediating the neurotrophic effects of PACAP on SH-SY5Y cells indicate that neither phospholipase C activation nor Ca2+/calmodulin-dependent kinase II (CAMKII) are involved.
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PMID:Neurotrophic actions of PACAP-38 and LIF on human neuroblastoma SH-SY5Y cells. 1850 35

Prosaposin triggers G-protein-coupled receptor (GPCR)-mediated protein kinase B (Akt)/extracellular signal-regulated kinase (ERK) phosphorylation cascades to exert its neurotrophic and myelinotrophic activity capable of preventing neural cell death and promoting neural proliferation and glial differentiation. In the present study, we investigated the down-stream neurotrophic signaling mechanism of prosaposin by which rat pheochromocytoma (PC-12) cells are protected from cell death induced by oxidative stress. When PC-12 cells were exposed to H2O2, the cells underwent abrupt shrinkage followed by apoptosis. Prosaposin treatment at as low as 1 nM protected PC-12 cells from cell death by the oxidative stress with the activation of an ERK phosphorylation cascade. Simultaneously, prosaposin blocked the oxidative stress induced-Akt phosphorylation that acts on the down-stream of caspase-3 activation. A MEK inhibitor, PD98059, or a phosphatidylinositol 3-kinase (PI3K) inhibitor, LY294002, abolished the survival effect of prosaposin on the oxidative stress-induced cell death. Furthermore, prosaposin blocked the oxidative stress-induced phosphorylations of c-Jun N-terminal kinase (JNK) and p38 stress-activated protein kinase. We further investigated the effect of prosaposin treatment on the phosphorylation of activating protein-1 (AP-1) complex components, c-Jun and activating transcription factor (ATF)-3. Western blot analysis demonstrated that prosaposin treatment at 100 ng/ml decreased the levels of c-Jun and ATF-3 induced by H2O2 stimulation. Our results suggest that prosaposin aids survival of PC-12 cells from oxidative stress not only by reducing the phosphorylation levels of JNK and p38, but also by regulating the c-Jun/AP-1 pathway.
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PMID:Molecular mechanism for neuro-protective effect of prosaposin against oxidative stress: its regulation of dimeric transcription factor formation. 1870 85

Mitogen-activated protein kinase (MAPK) cascades play important roles in regulating plant innate immune responses. In a genetic screen to search for mutants with constitutive defense responses, we identified multiple alleles of mpk4 and mekk1 that exhibit cell death and constitutive defense responses. Bimolecular fluorescence complementation (BiFC) analysis showed that both MPK4 and MEKK1 interact with MKK1 and MKK2, two closely related MAPK kinases. mkk1 and mkk2 single mutant plants do not have obvious mutant phenotypes. To test whether MKK1 and MKK2 function redundantly, mkk1 mkk2 double mutants were generated. The mkk1 mkk2 double mutant plants die at seedling stage and the seedling-lethality phenotype is temperature-dependent. Similar to the mpk4 and mekk1 mutants, the mkk1 mkk2 double mutant seedlings accumulate high levels of H2O2, display spontaneous cell death, constitutively express Pathogenesis Related (PR) genes and exhibit pathogen resistance. In addition, activation of MPK4 by flg22 is impaired in the mkk1 mkk2 double mutants, suggesting that MKK1 and MKK2 function together with MPK4 and MEKK1 in a MAP kinase cascade to negatively regulate innate immune responses in plants.
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PMID:MEKK1, MKK1/MKK2 and MPK4 function together in a mitogen-activated protein kinase cascade to regulate innate immunity in plants. 1898 20


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