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)

Increases in fetal hemoglobin have been identified after birth in several clinical settings associated with stressed or malignant erythropoiesis. To better understand the relationship between the expression of this fetal protein and growth, donated human erythroid progenitor cells were cultured in the presence of erythropoietin (EPO) plus the growth-modifying cytokine stem cell factor (SCF), and several growth-related signaling pathways were interrogated. Only the MEK1/2 inhibitor (PD98059) demonstrated significant effects on fetal hemoglobin. In the absence of PD98059, levels of fetal hemoglobin averaged 27.4% +/- 7.9% in EPO+SCF compared with 1.26% +/- 1.7% in EPO alone (P =.02). A linear dose response in levels of fetal hemoglobin to PD98059 was detected (0.16 microM = 27.13%, 0.8 microM = 19.6%, 4 microM = 12.2%, 20 microM = 1.54%). Western blot analyses revealed that SCF was required for phosphorylation of MEK and p44MAPK in this setting, and quantitative polymerase chain reaction demonstrated a significant increase in gamma-globin mRNA. Particular perturbations of growth-related signaling may also function to activate tissue-specific genes normally expressed during fetal development. This concept may be relevant for the development of new treatment rationales for beta hemoglobinopathies.
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PMID:A signaling mechanism for growth-related expression of fetal hemoglobin. 1459 35

Reactive oxygen species including H(2)O(2) activate an array of intracellular signalling cascades that are closely associated with cell death and cell survival pathways. The human neuroblastoma SH-SY5Y cell line is widely used as model cell system for studying neuronal cell death induced by oxidative stress. However, at present very little is known about the signalling pathways activated by H(2)O(2) in SH-SY5Y cells. Therefore, in this study we have investigated the effect of H(2)O(2) on extracellular signal-regulated kinase 1/2 (ERK1/2), c-Jun N-terminal kinase (JNK), p38 mitogen-activated protein kinase (p38 MAPK) and protein kinase B (PKB) activation in undifferentiated and differentiated SH-SY5Y cells. H(2)O(2) stimulated time and concentration increases in ERK1/2, JNK and PKB phosphorylation in undifferentiated and differentiated SH-SY5Y cells. No increases in p38 MAPK phosphorylation were observed following H(2)O(2) treatment. The phosphatidylinositol 3-kinase (PI-3K) inhibitors wortmannin and LY 294002 ((2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one) inhibited H(2)O(2)-induced increases in ERK1/2 and PKB phosphorylation. Furthermore, H(2)O(2)-mediated increases in ERK1/2 activation were sensitive to the MAPK kinase 1 (MEK1) inhibitor PD 98059 (2'-amino-3'-methoxyflavone), whereas JNK responses were blocked by the JNK inhibitor SP 600125 (anthra[1-9-cd]pyrazol-6(2H)-one). Treatment of SH-SY5Y cells with H(2)O(2) (1 mM; 16 h) significantly increased the release of lactate dehydrogenase (LDH) into the culture medium indicative of a decrease in cell viability. Pre-treatment with wortmannin, SP 600125 or SB 203580 (4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole; p38 MAPK inhibitor) had no effect on H(2)O(2)-induced LDH release from undifferentiated or differentiated SH-SY5Y cells. In contrast, PD 98059 and LY 294002 significantly decreased H(2)O(2)-induced cell death in both undifferentiated and differentiated SH-SY5Y cells. In conclusion, we have shown that H(2)O(2) stimulates robust increases in ERK1/2, JNK and PKB in undifferentiated and differentiated SH-SY5Y cells. Furthermore, the data presented clearly suggest that inhibition of the ERK1/2 pathway protects SH-SY5Y cells from H(2)O(2)-induced cell death.
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PMID:Activation of ERK1/2, JNK and PKB by hydrogen peroxide in human SH-SY5Y neuroblastoma cells: role of ERK1/2 in H2O2-induced cell death. 1472 4

1. Adenosine A(1), A(2A), and A(3) receptors (ARs) and extracellular signal-regulated kinase 1/2 (ERK1/2) play a major role in myocardium protection from ischaemic injury. In this study, we have characterized the adenosine receptor subtypes involved in ERK1/2 activation in newborn rat cardiomyocytes. 2. Adenosine (nonselective agonist), CPA (A(1)), CGS 21680 (A(2A)) or Cl-IB-MECA (A(3)), all increased ERK1/2 phosphorylation in a time- and dose-dependent manner. The combined maximal response of the selective agonists was similar to adenosine alone. Theophylline (nonselective antagonist) inhibited completely adenosine-mediated ERK1/2 activation, whereas a partial inhibition was obtained with DPCPX (A(1)), ZM 241385 (A(2A)), and MRS 1220 (A(3)). 3. PD 98059 (MEK1; ERK kinase inhibitor) abolished all agonist-mediated ERK1/2 phosphorylation. Pertussis toxin (PTX, G(i/o) blocker) inhibited completely CPA- and partially adenosine- and Cl-IB-MECA-induced ERK1/2 activation. Genistein (tyrosine kinase inhibitor) and Ro 318220 (protein kinase C, PKC inhibitor) partially reduced adenosine, CPA and Cl-IB-MECA responses, without any effect on CGS 21680-induced ERK1/2 phosphorylation. H89 (protein kinase A, PKA inhibitor) abolished completely CGS 21680 and partially adenosine and Cl-IB-MECA responses, without any effect on CPA response. 4. Cl-IB-MECA-mediated increases in cAMP accumulation suggest that A(3)AR-induced ERK1/2 phosphorylation involves adenylyl cyclase activation via phospholipase C (PLC) and PKC stimulation. 5. In summary, we have shown that ERK1/2 activation by adenosine in cardiomyocytes results from an additive stimulation of A(1), A(2A), and A(3)ARs, which involves G(i/o) proteins, PKC, and tyrosine kinase for A(1) and A(3)ARs, and Gs and PKA for A(2A)ARs. Moreover, the A(3)AR response also involves a cAMP/PKA pathway via PKC activation.
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PMID:Characterization of ERK1/2 signalling pathways induced by adenosine receptor subtypes in newborn rat cardiomyocytes. 1475 70

Mitogen-activated protein kinase kinase 2 (MEK2), the upstream kinase of extracellular signal-regulated kinase 1/2 (ERK1/2) was previously isolated as cancer cell dissociation related factor. In this study, to further clarify the regulatory mechanism of cancer cell dissociation, two hamster (PC-1.0 and PC-1) and human (Capan-2 and AsPC-1) pancreatic cancer cell lines were analyzed immunocytochemically with anti-ERK1, anti-ERK2 and anti-phosphorylated ERK1/2 (p-ERK1/2) antibodies. U0126 (a MEK1/2 inhibitor) significantly suppressed ERK2 and p-ERK1/2 expressions in PC-1.0 and AsPC-1 cells (P<0.05). Cancer cell dissociation factor (DF) markedly induced ERK2 and p-ERK1/2 expressions in PC-1 and Capan-2 cells (P<0.05), and the induced ERK2 and p-ERK1/2 expressions were inhibited by subsequent U0126-treatment (P<0.05). Simultaneously, light microscopic images showed that DF clearly induced cell dissociation in PC-1 and Capan-2 cells, while U0126-treatment induced cell aggregation in these pancreatic cancer cells. ERK2 activation is closely involved in cell dissociation of pancreatic cancer cells.
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PMID:Relationship between the expression of extracellular signal-regulated kinase 1/2 and the dissociation of pancreatic cancer cells: Involvement of ERK1/2 in the dissociation status of cancer cells. 1501 Aug 17

Extracellular signals may regulate mitogen-activated protein kinase (MAPK) cascades through a receptor-mediated mechanism. As a signaling superhighway to the nucleus, active Ras-MAPK cascades phosphorylate transcription factors and facilitate gene expression. In cultured rat striatal neurons, the present work systemically examined the linkage between glutamate receptors and the extracellular signal-regulated kinase 1/2 (ERK1/2) subclass of MAPK. We found that glutamate induced a rapid and transient phosphorylation of ERK1/2. Similar responses of ERK1/2 phosphorylation were also induced by the ligands selective for each of three subtypes of ionotropic receptors (NMDA, AMPA and kainate), although not by the subgroup-selective agonists for three subgroups of metabotropic glutamate receptors after 8-9 days in culture. The ERK1/2 phosphorylation induced by all ionotropic receptor agents was dose-, time- and Ca(2+) influx-dependent and occurred in neurons, but not glia. The NMDA-, AMPA- and kainate-induced ERK1/2 phosphorylation was blocked only by the antagonists selective for respective subtypes. The ERK1/2 phosphorylation induced by these agents was also sensitive to the MAPK kinase 1 (MEK1) inhibitor PD98059 and the MEK1/2 inhibitor U0126. In a further attempt to evaluate the role of active ERK1/2 in activating a downstream transcription factor cAMP response element-binding protein (CREB), NMDA, AMPA, and kainate were found to increase CREB phosphorylation. The NMDA- and AMPA/kainate-induced CREB phosphorylation was completely and partially blocked by U0126, respectively. These results revealed a positive linkage between ionotropic glutamate receptors and MEK-sensitive ERK1/2 phosphorylation in striatal neurons. The active ERK1/2 cascade activates the downstream transcription factor CREB to participate in the regulation of gene expression.
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PMID:Regulation of MAPK/ERK phosphorylation via ionotropic glutamate receptors in cultured rat striatal neurons. 1501 79

Interactions between the cyclin-dependent kinase (CDK) inhibitor flavopiridol and the proteasome inhibitor bortezomib were examined in Bcr/Abl(+) human leukemia cells. Coexposure of K562 or LAMA84 cells to subtoxic concentration of flavopiridol (150-200 nM) and bortezomib (5-8 nM) resulted in a synergistic increase in mitochondrial dysfunction and apoptosis. These events were associated with a marked diminution in nuclear factor kappaB (NF-kappaB)/DNA binding activity; enhanced phosphorylation of SEK1/MKK4 (stress-activated protein kinase/extracellular signal-related kinase 1/mitogen-activated protein kinase kinase 4), c-Jun N-terminal kinase (JNK), and p38 mitogen-activated protein kinase (MAPK); down-regulation of Bcr/Abl; and a marked reduction in signal transducer and activator of transcription 3 (STAT3) and STAT5 activity. In imatinib mesylate-resistant K562 cells displaying increased Bcr/Abl expression, bortezomib/flavopiridol treatment markedly increased apoptosis in association with down-regulation of Bcr/Abl and BclxL, and diminished phosphorylation of Lyn, Hck, CrkL, and Akt. Parallel studies were performed in imatinib mesylate-resistant LAMA84 cells exhibiting reduced expression of Bcr/Abl but a marked increase in expression/activation of Lyn and Hck. Flavopiridol/bortezomib effectively induced apoptosis in these cells in association with Lyn and Hck inactivation. The capacity of flavopiridol to promote bortezomib-mediated Bcr/Abl down-regulation and apoptosis was mimicked by the positive transcription elongation factor-b (P-TEFb) inhibitor DRB (5,6-dichloro 1-beta-d-ribofuranosylbenzinida-sole). Finally, the bortezomib/flavopiridol regimen also potently induced apoptosis in Bcr/Abl(-) human leukemia cells. Collectively, these findings suggest that a strategy combining flavopiridol and bortezomib warrants further examination in chronic myelogenous leukemia and related hematologic malignancies.
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PMID:Bortezomib and flavopiridol interact synergistically to induce apoptosis in chronic myeloid leukemia cells resistant to imatinib mesylate through both Bcr/Abl-dependent and -independent mechanisms. 1503 84

A high-throughput screen for Ras-mitogen-activated protein kinase (MAPK) signaling inhibitors identified two series (class 1 and 2) of substituted 4-anilino-3-quinolinecarbonitriles as potent (IC(50)s <10 nmol/L) mitogen-activated protein/extracellular signal-regulated kinase 1 (MEK1) kinase inhibitors. These compounds had cyanoquinoline cores, but differed in their respective aniline groups [1a, 1b: 4-phenoxyphenylaniline; 2a, 2b: 3-chloro-4-(1-methylimidazol-2-sulfanyl)aniline]. These compounds were competitive inhibitors of ATP binding by MEK1 kinase, and they had minimal or no effect on Raf, epidermal growth factor receptor (EGFR), Akt, cyclin-dependent kinase 4 (CDK4), or MK2 kinases at concentrations >100-fold higher than those that inhibited MEK1 kinase. Both class 1 and 2 compounds inhibited in vitro growth of human tumor cell lines. A class 2 compound (2b) was the most potent inhibitor of human tumor cell growth in vitro, and this effect was linked to distinct suppression of MAPK phosphorylation in cells. Compound 2b did not affect phosphorylation status of other kinases, such as EGFR, Akt, and stress-activated protein (SAP)/c-jun-NH kinase (Jnk); nor did it affect overall tyrosine phosphorylation level in cells. However, compound 2b did inhibit MEK1 phosphorylation in cells. Inhibition of MEK1 phosphorylation by 2b was not due to a major effect on Raf kinase activity, because enzyme assays showed minimal Raf kinase inhibition. We believe compound 2b inhibits kinase activity upstream of Raf, and thereby affects MEK1 phosphorylation in cells. Even with the dual effect of 2b on MEK and MAPK phosphorylation, this compound was well tolerated and significantly inhibited growth of the human colon tumor cell line LoVo (at 50 and 100 mg/kg BID, i.p.) in a nude mouse xenograft model.
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PMID:Identification of 4-anilino-3-quinolinecarbonitrile inhibitors of mitogen-activated protein/extracellular signal-regulated kinase 1 kinase. 1521 Aug 62

A cytotoxic enterotoxin (Act) of Aeromonas hydrophila possesses several biological activities, induces an inflammatory response in the host, and causes apoptosis of murine macrophages. In this study, we utilized five target cell types (a murine macrophage cell line (RAW 264.7), bone marrow-derived transformed macrophages, murine peritoneal macrophages, and two human intestinal epithelial cell lines (T84 and HT-29)) to investigate the effect of Act on mitogen-activated protein kinase (MAPK) pathways and mechanisms leading to apoptosis. As demonstrated by immunoprecipitation/kinase assays or Western blot analysis, Act activated stress-associated p38, c-Jun NH(2)-terminal kinase (JNK), and extracellular signal-regulated kinase 1/2 (ERK1/2) in these cells. Act also induced phosphorylation of upstream MAPK factors (MAPK kinase 3/6 (MKK3/6), MKK4, and MAP/ERK kinase 1 (MEK1)) and downstream effectors (MAPK-activated protein kinase-2, activating transcription factor-2, and c-Jun). Act evoked cell membrane blebbing, caspase 3-cleavage, and activation of caspases 8 and 9 in these cells. In macrophages that do not express functional tumor necrosis factor receptors, apoptosis and caspase activities were significantly decreased. Immunoblotting of host whole cell lysates revealed Act-induced up-regulation of apoptosis-related proteins, including the mitochondrial proteins cytochrome c and apoptosis-inducing factor. However, mitochondrial membrane depolarization was not detected in response to Act. Taken together, the data demonstrated for the first time Act-induced activation of MAPK signaling and classical caspase-associated apoptosis in macrophages and intestinal epithelial cells. Given the importance of MAPK pathways and apoptosis in inflammation-associated diseases, this study provided new insights into the mechanism of action of Act on host cells.
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PMID:Aeromonas hydrophila cytotoxic enterotoxin activates mitogen-activated protein kinases and induces apoptosis in murine macrophages and human intestinal epithelial cells. 1521 44

Endothelial nitric oxide synthase (eNOS) plays an important role in maintaining blood pressure homeostasis and vascular integrity. Natural dietary flavoniods are thought to protect against cardiovascular diseases by acting as antioxidants and vasodilatants. This study examined the effect of cyanidin-3-glucoside (Cy3G), a typical anthocyanin pigment, on eNOS expression. Treatment of bovine artery endothelial cells (BAECs) with Cy3G for 8 hours of enhanced eNOS protein expression in a dose- and time-dependent manner was determined by Western blot analysis. Longer incubation (12, 16, and 24 hours) of BAECs with 0.1 micromol/L of Cy3G caused a further increase in eNOS expression, and subsequently Cy3G also significantly increased nitric oxide output 2-fold (24 hours). Furthermore, Cy3G stimulated the phosphorylation of Src and extracellular signal-regulated kinase 1/2 (ERK1/2) in a time-dependent manner. An Src kinase inhibitor, pp2, and MEK inhibitor, PD98059, blocked the ERK1/2 phosphorylation and eNOS expression. Transfection with dominant-negative Src cDNA also inhibited the eNOS expression stimulated by Cy3G. In addition, stimulation with Cy3G for 30 minutes resulted in a phosphorylation of Sp1 that was blocked by PD98059. Cy3G enhanced the binding activity of the transcription factor Sp1 to the GC box in the proximal eNOS promoter of BAECs, as revealed by chromatin immunoprecipitation assay. The present study demonstrated that Cy3G induced eNOS expression and escalated NO production via an Src-ERK1/2-Sp1 signaling pathway in vascular endothelial cells. Increased eNOS expression may help to ameliorate endothelial dysfunction, harmonize blood pressure, and prevent atherosclerosis as long-term beneficial effects of flavoniods.
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PMID:Upregulation of endothelial nitric oxide synthase by cyanidin-3-glucoside, a typical anthocyanin pigment. 1522 77

The involvement of the extracellular signal-regulated kinase 1/2 (ERK1/2) cascade in long-lasting potentiation of synaptic transmission, induced by tetraethylammonium (TEA) or by elevated extracellular calcium concentration, was investigated in layer V horizontal connections within motor cortex in rat brain slices. Brief application of TEA (25 mM) resulted in a long-lasting potentiation of field potentials by 54+/-12%. A transient exposure of slices to elevated extracellular calcium (5 mM) induced long-lasting potentiation of responses reaching 30+/-8%. The induction of both forms of potentiation was prevented by the exposure of slices to inhibitors of the upstream activator of ERK 1/2, MEK (ERK kinase), U0126 (20 microM) and PD 98059 (50 microM). PhosphoERK2 immunoreactivity was transiently increased above baseline levels 15 min after termination of the exposure of slices to either TEA or elevated calcium concentration. Both forms of potentiation were partially occluded by Sp-adenosine 3',5'-cyclic monophosphorothioate triethylammonium salt (Sp-cAMPS; 100 microM), an activator of cAMP-dependent protein kinase (PKA), and they were blocked after preincubation with Rp-adenosine 3',5'-cyclic monophosphorothioate triethylammonium salt (Rp-cAMPS; 100 microM), a specific inhibitor of PKA activation by cAMP. It has previously been shown that TEA-induced potentiation represents a N-methyl-d-aspartate (NMDA) receptor-independent form of persistent synaptic enhancement, and, on the contrary, calcium-induced potentiation depends on NMDA receptors. Thus, the activation of PKA and the ERK1/2 cascade are required for two forms of chemically induced long-lasting increases of synaptic efficacy in slices of rat motor cortex.
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PMID:Chemically-induced long-term potentiation in rat motor cortex involves activation of extracellular signal-regulated kinase cascade. 1534 67


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