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)

We evaluated whether KIOM-79, a mixture of extracts obtained from Puerariae lobata, Magnolia officinalis, Glycyrrhiza uralensis and Euphorbia pekinensis, could inhibit vascular endothelial growth factor (VEGF) expression in human retinal pigment epithelial (RPE) cells cultured under high glucose (HG, 25mM) or S100b (a specific ligand of the receptor for advance glycation end products (RAGE), 5microg/ml). In this study, the effect of KIOM-79 on HG or S100b-induced VEGF expression was investigated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, RT-PCR, ELISA, and Western blot on human RPE cells. The MTT assay (p<0.01) revealed that KIOM-79 (up to 1mg/ml) had no effect on cell growth. HG or S100b induced an increase in expression of VEGF at both mRNA and protein levels (p<0.05; p<0.01 versus control). The increase in VEGF expression by HG or S100b was dose- and time-dependently prevented by KIOM-79 (p<0.05 versus 25mM glucose; p<0.01 versus S100b). Also, KIOM-79 inhibited protein kinase C (PKC)-alpha/beta(alpha) and p38 mitogen-activated protein kinase (MAPK) activation. Our results demonstrate that KIOM-79 can inhibit VEGF expression via inhibition of the MAPK and PKC pathway.
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PMID:KIOM-79 inhibits high glucose or AGEs-induced VEGF expression in human retinal pigment epithelial cells. 1738 27

Increased vascular disease occurs with low albumin (human serum albumin, HSA), possibly reflecting specific inhibition of endothelial apoptosis reported for tissue culture. Despite the reported specificity for endothelial protection by HSA, the high but physiological concentrations needed appear more consistent with non-specific low-affinity interactions. We reconcile this contradiction by demonstrating protection is mediated by a partially cryptic HSA protein domain, which becomes more exposed and active following cyanogen bromide fragmentation (p < 0.001). Also, although others reported HSA radical scavenging and bound lipids as important for inhibiting apoptosis in non-endothelial cell types, we demonstrate the protective effect for endothelium is unaffected when HSA radical scavenging is blocked by alkylation, or following delipidation. Further probing the mechanism responsible, we found that the G-coupled protein inhibitors pertussis toxin and suramin reduced protection of endothelium by HSA (p < 0.005), while the tyrosine kinase inhibitor genistein had no effect. Consistent with a role for phosphoinositide 3 kinase (PI3K) was inhibition by both wortmannin and LY294002 (p < 0.05), as well as phosphorylation of Akt, while MAP kinase inhibitors had no effect. We conclude the active site in HSA inhibiting endothelial apoptosis is partially cryptic, and acts via a G-coupled protein PI3K-dependent mechanism.
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PMID:The anti-apoptotic activity of albumin for endothelium is mediated by a partially cryptic protein domain and reduced by inhibitors of G-coupled protein and PI-3 kinase, but is independent of radical scavenging or bound lipid. 1743 60

1. We have isolated a novel human erythrocyte-derived depressing factor (EDDF) that has a significant antihypertensive effect in various rat models of hypertension. The aim of the present study was to examine the mechanisms of action of EDDF on vascular function in two-kidney, one-clip (2K1C) renovascular hypertensive rats. 2. The EDDF was prepared from human erythrocytes. Experiments were performed in 18 male Wistar rats. The vascular ring perfusion assay and a two-photon laser scanning fluorescence microscope (TMP) were used to evaluate the vascular contractile response. The effects of EDDF on phenylephrine (PE)- and noradrenaline (NA)-induced vascular contraction were evaluated in 2K1C hypertensive rats. The proliferation and DNA synthesis in vascular smooth muscle cells (VSMC) were determined using the [3H]-TdR (thymidine) incorporation and 3-(4,5-dimethyl-2 thiazoyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assays. Flow cytometry, reverse transcription-polymerase chain reaction and western blots were used to measure cell cycle and apoptotic profiles, platelet-derived growth factor (PDGF)-A expression and the activity of extracellular signal-regulated kinase (ERK)-1/2, as well as the expression of cyclin D1 and cyclin-dependent kinase (CDK) 4. 3. At 10(-5) g/mL, EDDF significantly decreased the PE- and NA-induced hypertensive vascular contraction. In addition, EDDF inhibited DNA synthesis in primary VSMC from 2K1C rats. The mRNA expression of PDGF-A in VSMC was twofold higher in 2K1C rats compared with control rats, whereas EDDF significantly inhibited the increment in PDGF-A mRNA expression. In addition, EDDF inhibited the phosphorylation of ERK1/2 and decreased the expression of cyclin D1 and CDK4; p21 (Cip1) levels were increased after treatment with EDDF. 4. In conclusion, EDDF inhibits VSMC proliferation in 2K1C rats through G0/G1 cell cycle arrest. The effects may be mediated, in part, by enhanced expression of p21 (Cip1) and the inhibition of ERK1/2 phosphorylation and the expression of cyclin D1/CDK4 and PDGF-A.
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PMID:Protective role of a novel erythrocyte-derived depressing factor on blood vessels of renovascular hypertensive rats. 1743 6

In order to examine the neuroprotective effects of the alpha7 nicotinic receptor (nAChR) in relationship to the pathogenesis of Alzheimer's disease (AD), neuroblastoma (SH-SY5Y) cells were transfected with small interference RNAs (siRNAs) that targets specifically towards alpha7 nAChR or exposed to 20microM 3-[2,4-dimethoxybenzylidene] anabaseine (DMXB), a selective agonist of this same receptor. The levels of alpha7 nAChR mRNA and protein were measured by RT-PCR and Western blotting, respectively. The levels of the alpha-form of secreted amyloid precursor protein (alphaAPPs), total APP and the extracellular signal-regulated kinase 1/2 (ERK1/2) were also determined by Western blotting. SH-SY5Y cells transfected with siRNA or exposed to DMXB were then treated with 1microM Abeta(25-35), following which the levels of lipid peroxidation and rate of reduction of MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] were characterized by utilizing spectrophotometric procedures. Compared to controls, SH-SY5Y cells transfected with siRNA expressed the decreases in the levels of alpha7 nAChR mRNA and protein by 81% and 69% lower levels, respectively; exhibited reduced levels of the alphaAPPs and ERK1/2 proteins; and demonstrated enhanced lipid peroxidation and a decreased rate of MTT reduction. In cells exposed to DMXB, the level of alpha7 nAChR protein was elevated by 23%, with no alteration in the content of the corresponding mRNA; the levels of the alphaAPPs and ERK1/2 proteins were increased. Inhibition of the expression of the alpha7 nAChR gene enhanced the toxicity exerted by Abeta, whereas stimulation of this receptor attenuated this toxicity exerted. These findings indicate that alpha7 nAChR may play a significant neuroprotective role by enhancing cleavage of APP by alpha-secretase, regulating signal transduction, improving antioxidant defenses and inhibiting the toxicity of Abeta, which is connected with the pathogenesis of AD.
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PMID:The consequences of reducing expression of the alpha7 nicotinic receptor by RNA interference and of stimulating its activity with an alpha7 agonist in SH-SY5Y cells indicate that this receptor plays a neuroprotective role in connection with the pathogenesis of Alzheimer's disease. 1749 9

The M2 muscarinic acetylcholine receptor (mAChR) possesses at least one binding site for allosteric modulators that is dependent on the residues (172)EDGE(175), Tyr(177), and Thr(423). However, the contribution of these residues to actions of allosteric agonists, as opposed to modulators, is unknown. We created mutant M2 mAChRs in which the charge of the (172)EDGE(175) sequence had been neutralized and each Tyr(177) and Thr(423) was substituted with alanine. Radioligand binding experiments revealed that these mutations had a profound inhibitory effect on the prototypical modulators gallamine, alcuronium, and heptane-1,7-bis-[dimethyl-3'-phthalimidopropyl]-ammonium bromide (C7/3-phth) but minimal effects on the orthosteric antagonist [3H]N-methyl scopolamine. In contrast, the allosteric agonists 4-I-[3-chlorophenyl]carbamoyloxy)-2-butynyltrimethylammnonium chloride (McN-A-343), 4-n-butyl-1-[4-(2-methylphenyl)-4-oxo-1-butyl] piperidine hydrogen chloride (AC-42), and the novel AC-42 derivative 1-[3-(4-butyl-1-piperidinyl)propyl]-3,4-dihydro-2(1H)-quinolinone (77-LH-28-1) demonstrated an increased affinity or proportion of high-affinity sites at the combined EDGE-YT mutation, indicating a different mode of binding to the prototypical modulators. Subsequent functional assays of extracellular signal-regulated kinase (ERK)1/2 phosphorylation and guanosine 5'-(gamma-[(35)S]thio)triphosphate ([(35)S]GTPgammaS) binding revealed minimal effects of the mutations on the orthosteric agonists acetylcholine (ACh) and pilocarpine but a significant increase in the efficacy of McN-A-343 and potency of 77-LH-28-1. Additional mutagenesis experiments found that these effects were predominantly mediated by Tyr(177) and Thr(423), rather than the (172)EDGE(175) sequence. The functional interaction between each of the allosteric agonists and ACh was characterized by high negative cooperativity but was consistent with an increased allosteric agonist affinity at the combined EDGE-YT mutant M2 mAChR. This study has thus revealed a differential role of critical allosteric site residues on the binding and function of allosteric agonists versus allosteric modulators of M2 mAChRs.
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PMID:Structure-function studies of allosteric agonism at M2 muscarinic acetylcholine receptors. 1752 29

VEGF (vascular endothelial growth factor), a potent angiogenic molecule specific for vascular endothelial cells, is overexpressed in most tumours including MM (multiple myeloma) and closely associated with tumour growth and prognosis. It has been shown that a soluble fragment of the VEGF receptor Flt-1 (Fms-like tyrosine kinase-1) [sFlt-1 (soluble Flt-1)] has antiangiogenic properties by way of its antagonist activity against VEGF. VEGF and its receptors have been shown to be targets for treating tumours. In the present study, sFlt-1 gene was expressed in Pichia pastoris and the product was applied for studying the effect on KM3 MM cells. sFlt-1 gene was inserted into the pPICZalphaA vector and the expressed product was analysed by SDS/PAGE, immunoblot and ELISA. The sFlt-1 protein was expressed by 0.5% (v/v) methanol induction and it accumulated up to 23% of total proteins in the supernatant. The product was further purified with metal-chelating resin [Ni-NTA (Ni(2+)-nitrilotriacetate)]. The functional analysis of the sFlt-1 protein was performed with HUVEC (human umbilical-vein endothelial cells) proliferation assay. We next showed that the sFlt-1 protein acted directly on MM cells and inhibited the VEGF-induced proliferation of MM cells with MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide] and (3)H uptake assay. The sFlt-1 protein blocked VEGF-induced ERK (extracellular-signal-regulated kinase) phosphorylation and inhibited the MAPK (mitogen-activated protein kinase) signalling cascades. The present study demonstrated that anti-MM activity of the sFlt-1 protein, coupled with its antiangiogenic effects, provides the basis for clinical trials of this agent to improve the outcome in MM.
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PMID:Expression of soluble Flt-1 gene in Pichia pastoris and the effect of the product on multiple-myeloma cells in vitro. 1761 89

Acetylcholine may play a role in cell activation and airway inflammation. We evaluated the levels of both mRNA and protein of muscarinic M(1), M(2), M(3) receptors in human bronchial epithelial cell line (16HBE). 16HBE cells were also stimulated with acetylcholine and extracellular signal-regulated kinase1/2 (ERK1/2) and NFkB pathway activation as well as the IL-8 release was assessed in the presence or absence of the inhibitor of Protein-kinase (PKC) (GF109203X), of the inhibitor of mitogenic activated protein-kinase kinase (MAPKK) (PDO9805), of the inhibitor of kinaseB-alpha phosphorilation (pIkBalpha) (BAY11-7082), and of muscarinic receptor antagonists tiotropium bromide, 4-Diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP), telenzepine, gallamine. Additionally, we tested the IL-8-mediated neutrophil chemotactic activity of 16HBE supernatants stimulated with acetylcholine in the presence or absence of tiotropium. 16HBE cells expressed both protein and mRNA for muscarinic M(3), M(2) and M(1) receptors with levels of muscarinic M(3) receptor>muscarinic M(1) receptor>muscarinic M(2) receptor. Acetylcholine (10 microM) significantly stimulated ERK1/2 and NFkB activation as well as IL-8 release in 16HBE cells when compared to basal values. Furthermore, while the use of tiotropium, 4-DAMP, GF109203X, PDO98059, BAY11-7082 completely abolished these events, the use of telenzepine and gallamine were only partially able to downregulate these effects. Additionally, acetylcholine-mediated IL-8 release from 16HBE cells significantly increased chemotaxis toward neutrophils and this effect was blocked by tiotropium. In conclusion, acetylcholine activates the release of IL-8 from 16HBE involving PKC, ERK1/2 and NFkB pathways via muscarinic receptors, suggesting that it is likely to contribute to IL-8 related neutrophilic inflammatory disorders in the airway. Thus, muscarinic antagonists may contribute to control inflammatory processes in airway diseases.
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PMID:Acetylcholine mediates the release of IL-8 in human bronchial epithelial cells by a NFkB/ERK-dependent mechanism. 1824 99

Hepatocellular carcinoma has been described to exhibit characteristics similar to that of neuroendocrine tumors (NETs). This includes similar anti-neoplastic responses to extracellular signal-regulated kinase (ERK) activation. NET cells and HepG2 cells have both shown growth inhibition with ERK activation. ZM336372, a Raf-1 activating agent, has been shown to cause growth inhibition and suppression of hormone secretion in a neuroendocrine cell line. Here we examine treatment of the HepG2 cell line with ZM336732 to determine if a similar anti-proliferative response will be obtained. HepG2 cells were treated with ZM336372 or solvent (dimethyl sulfoxide). The resulting effect on the proliferation was measured using the 3,4-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Western blot analysis was performed to examine the activation of the Raf-1/mitogen-activated protein kinase kinase/ERK pathway, chromogranin A production, and p21CIP1 level. Growth inhibition was observed with ZM336372 in a dose-dependent fashion. Minimal baseline phosphorylation of ERK 1/2 was observed; however, activation was observed after treatment with ZM336372. Chromogranin A secretion was suppressed due to treatment with ZM336372. A dose-dependent up-regulation of p21CIP1 was observed in response to ZM336372 treatment. ZM336372 causes growth inhibition, suppression of hormone secretion, and up-regulation of cell cycle inhibitors in a human hepatocellular carcinoma cell line, similar to that previously seen in NETs.
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PMID:ZM336372, a Raf-1 activator, causes suppression of proliferation in a human hepatocellular carcinoma cell line. 1829 43

The objective of this study was to determine whether the dual action of nitric oxide (NO) on cardiomyocyte cell viability is mediated through p38 mitogen-activated protein kinase (MAPK)-induced cell death and extracellular signal-regulated kinase (ERK1/2)-mediated cell survival pathways, and whether either of these is mediated through a cGMP-protein kinase G (PKG) pathway. Cell viability of embryonic chick cardiomyocytes was assessed by the MTT assay, which is based on the ability of viable cells to reduce 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide. The NO donor sodium nitroprusside (SNP) produced a significant (P < 0.01) concentration-dependent reduction in cell viability or increase in cell death. Sodium nitroprusside induced ERK1/2 phosphorylation, and the mitogen-activated protein kinase (MEK1/2) inhibitor PD 98059 significantly increased cell death. In contrast, SB202190, a relatively selective inhibitor of p38 MAPK, did not affect SNP-induced cell death. The cardioprotective effect of NO was prbably mediated in part via cGMP because 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, a selective inhibitor of NO-sensitive guanylyl cyclase, produced a significant enhancement of SNP-induced cell death. In contrast, the PKG inhibitor KT5823 did not affect cell viability. In summary, these data suggest that NO, via stimulation of soluble guanylyl cyclase, activates MEK1/2 whose product, ERK1/2, protects against cell death. In contrast, SNP-induced p38 MAPK activation does not modulate NO-induced cardiomyocyte cell death. Not all cGMP targets affect NO-induced cell death, since the PKG pathway does not enhance or suppress NO-induced cardiomyocyte cell death. Enhancement of the ERK1/2 responses to NO may permit the beneficial effects of NO to predominate.
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PMID:The action of nitric oxide to enhance cell survival in chick cardiomyocytes is mediated through a cGMP and ERK1/2 pathway while p38 mitogen-activated protein kinase-dependent pathways do not alter cell death. 1834 57

Vascular smooth muscle cell (VSMC) proliferation and migration in response to platelet-derived growth factor (PDGF) play an important role in the development of atherosclerosis and restenosis. Recent evidence indicates that PDGF increases intracellular levels of reactive oxygen species in VSMCs and that both PDGF-induced VSMC proliferation and migration are reactive oxygen species-dependent. Danshen is a representative oriental medicine used for the treatment of vascular disease. Previously, we reported that magnesium lithospermate B, an active component of Danshen, is a potent antioxidant. Thus we investigated the therapeutic potential of magnesium lithospermate B in neointimal formation after carotid artery injury in rats along with its effects on the PDGF signaling pathway for stimulating VSMC proliferation and migration in vitro. PDGF is dimeric glycoprotein composed of two A or two B chains. In this study, we used PDGF-BB, which is one of the isoforms of PDGF (i.e., PDGF-AA, PDGF-BB, and PDGF-AB). Our results demonstrated that magnesium lithospermate B directly scavenged reactive oxygen species in a xanthine/xanthine oxidase system and reduced PDGF-BB-induced intracellular reactive oxygen species generation in VSMCs. In a rat carotid artery balloon injury model, magnesium lithospermate B treatment (10 mg/kg/day, i.p) showed a significant effect on the prevention of neointimal formation compared with vehicle treatment. In cultured VSMCs, magnesium lithospermate B significantly attenuated PDGF-BB-induced cell proliferation and migration as measured by 3-[4,5-dimethyl-2-thiazolyl]-2,5-diphenyl-2-tetrazolium bromide (MTT) assay and transwell migration assays, respectively. Further, magnesium lithospermate B inhibited PDGF-BB-induced phosphorylation of phospatidylinositol 3-kinase (PI3K)/Akt and mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) pathways by scavenging reactive oxygen species. Together, these data indicated that magnesium lithospermate B, a potent reactive oxygen species scavenger, prevented both injury-induced neointimal formation in vivo and PDGF-BB-induced VSMC proliferation and migration in vitro, suggesting that magnesium lithospermate B may be a promising agent to prevent atherosclerosis and restenosis following angioplasty.
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PMID:Therapeutic effect of magnesium lithospermate B on neointimal formation after balloon-induced vascular injury. 1838 4


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