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)

The Tpl-2 kinase activates the nuclear factor of activated T cells (NFAT) and induces IL-2 expression in T-cell lines. Here we show that the activation of the IL-2 promoter by Tpl-2 is inhibited by mutant signaling molecules that inhibit the mitogen-activated protein kinase (MAPK) or the calcineurin/NFAT pathways and is promoted by combinations of signaling molecules that activate these pathways. We, therefore, conclude that signals generated by the convergence of the MAPK and the calcineurin/NFAT pathway are necessary and sufficient for the activation of the IL-2 promoter by Tpl-2. The activation of both the IL-2 promoter and an NFAT-driven minimal promoter were shown to depend on signals transduced by Raf1. However, it was only the IL-2 promoter whose activation by Tpl-2 was fully blocked by the dominant negative mutant MEK1S218/222A and the MEK1/MEK2 inhibitor PD098059. Since the activation of NFAT is MAPK-dependent these findings suggested that the activation of MAPK by Tpl-2 is either independent or only partially dependent on MEK1 and MEK2. In addition, they suggested that the activation of the IL-2 promoter is under the control of not only NFAT but also a second factor whose activation is MEK-dependent. Experiments in COS-1 and EL-4 cells confirmed both hypotheses and revealed that the second factor activated by Tpl-2 is NF-kappaB. While the activation of the IL-2 promoter and an NFAT-driven minimal promoter by Tpl-2 was fully blocked by the dominant negative mutant NFAT delta418, it was only partially blocked by the calcineurin inhibitor cyclosporin A suggesting that the Tpl-2-mediated NFAT activation is under the control of a combination of calcineurin-dependent and independent pathways. Both pathways were fully blocked by Bcl-2 or Bcl-X(L).
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PMID:Tpl-2 induces IL-2 expression in T-cell lines by triggering multiple signaling pathways that activate NFAT and NF-kappaB. 984 Sep 24

The early growth response gene-1 (Egr-1) is a transcription factor that plays an important role in cell growth and differentiation. It has been known that Egr-1 expression is down-regulated in many types of tumor tissues, including human fibrosarcoma HT1080 cells, and introduction of the Egr-1 gene into HT1080 cells inhibits cell growth and tumorigenic potential. Trifluoperazine (TFP), a phenothiazine class calmodulin antagonist, is known to inhibit DNA synthesis and cell proliferation and potentially important in antitumor activities. To understand the regulatory mechanism of Egr-1, we investigated the effect of TFP on expression of Egr-1 in HT1080 cells. Herein, we report that Egr-1 expression was increased by TFP in synergy with serum at the transcriptional level. Both the Ca(2+)/calmodulin-dependent protein kinase II inhibitor KN62 and the calcineurin inhibitor cyclosporin A enhanced TFP-dependent increase of Egr-1, suggesting that the Ca(2+)/calmodulindependent pathway plays a role in regulation of Egr-1 expression in HT1080 cells. The TFP-stimulated increase of the Egr-1 protein was preferentially inhibited by the MEK-specific inhibitor PD98059. In addition, activation of human Egr-1 promoter and the transcriptional activation of the ternary complex factor Elk-1 induced by TFP were inhibited both by pretreatment of PD98059 and by expression of the dominant-negative RasN17. These results indicate that the Ras/MEK/Erk/Elk-1 pathway is necessary for TFP-induced Egr-1 expression. We propose that the calmodulin antagonist TFP stimulates Egr-1 gene expression by modulating Ras/MEK/Erk and activation of the Elk-1 pathway in human fibrosarcoma HT1080 cells.
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PMID:Induction of early growth response-1 gene expression by calmodulin antagonist trifluoperazine through the activation of Elk-1 in human fibrosarcoma HT1080 cells. 1112 17

Prolonged eosinophil survival is an essential step in the late and chronic phases of allergic inflammation and is regulated by the eosinophil survival cytokines. Our work has demonstrated that tumour necrosis factor (TNF)-alpha enhances survival (Trypan blue exclusion test) of human peripheral blood eosinophils from mildly allergic patients in a dose-dependent manner. The survival activity of TNF-alpha was inhibited by anti-TNF-RI, anti-TNF-RII antagonist antibodies and anti-granulocyte-monocyte colony-stimulating factor (GM-CSF) neutralizing antibodies but not by anti-interleukin (IL)-3 or anti-IL-5 antibodies. Furthermore, TNF-alpha-induced GM-CSF release from eosinophils. Anti-TNF-alpha antibodies also inhibited GM-CSF release from eosinophils induced by rat mast cell sonicate, which enhances eosinophil survival. To define the signal transduction pathway involved in GM-CSF production, eosinophils were incubated either with various mitogen-activated protein kinases (MAPK) inhibitors (MEK, JNK, P38), or Cyclosporin A (calcineurin inhibitor), or MG-132 (proteasome inhibitor). Only the proteasome inhibitor significantly decreased both TNF-alpha-enhanced eosinophil survival (from 38.1+/-4.1% to 13.3+/-1.4%) and GM-CSF release (from 6.2+/-0.7 pg/ml to 0.3+/-0.1 pg/ml). TNF-alpha also induced nuclear factor-kappaB (NF-kappaB) translocation to the nucleus, an essential step in GM-CSF mRNA production. All these findings provide evidence that NF-kappaB is involved in TNF-alpha-enhanced eosinophil survival through the regulation of GM-CSF production by eosinophils.
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PMID:Mechanism of tumour necrosis factor alpha mediated eosinophil survival. 1150 5

The present study examined the role of calcineurin in insulin-like growth factor (IGF)-1-induced hypertrophy in primary cultures of adult rat ventricular myocytes (ARVM), prepared from the ventricles of 14-16-week-old male Sprague-Dawley rats. The effects of several humoral factors, including phenylephrine, angiotensin II, endothelin-1, IGF-1 and interleukin-6, on the morphology of ARVM were studied. Myocyte surface area was significantly increased by IGF-1 (2,268 +/- 571 to 3,018 +/- 836 microm2, p < 0.01), but not by other humoral factors. This hypertrophic effect of IGF-1 was blocked by genistein (tyrosine kinase inhibitor), PD98059 (MEK inhibitor). These findings suggest that IGF-1 produces ARVM hypertrophy by a tyrosine kinase-MEK mediated pathway as has been reported in neonatal cardiomyocytes. IGF-1-mediated ARVM hypertrophy was also attenuated by cyclosporine A (calcineurin inhibitor), and staurosporine and chelerythrine (protein kinase C inhibitors). IGF-1 markedly increased calcineurin activity (8.7 +/- 1.2 to 98.0 +/- 54.3 pmol x h(-1) mg(-1), p < 0.01), and this activation was completely blocked by pre-treatment with cyclosporine A (8.5 +/- 11.4pmol x h(-1) x mg(-1), p < 0.01) and chelerythrine (2.3 +/- 2.7 pmol x h(-1) mg(-1), p < 0.01). It appears that IGF-1 activates calcineurin by a protein kinase C-dependent pathway. Increased mRNA expression of atrial natriuretic factor by IGF-1 was inhibited by cyclosporine A (p < 0.01). The findings indicate that IGF-1 induces ARVM hypertrophy by protein kinase C and calcineurin-related mechanisms. The fact that elevated calcineurin activity and induced atrial natriuretic factor mRNA expression by IGF-1 were blocked by cyclosporine A further supports the hypothesis that calcineurin is critically involved in IGF-1-induced ARVM hypertrophy.
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PMID:Role of calcineurin in insulin-like growth factor-1-induced hypertrophy of cultured adult rat ventricular myocytes. 1154 82

CXCR6, the receptor for the membrane-anchored chemokine, CXCL16, is expressed on a subset of CCR5-bearing memory T cells, and may play a role in recruiting these cells to sites of inflammation. Here, we set out to determine the effect of T cell activation on CXCR6 expression. Highly purified human peripheral blood T cells were cultured for 7-8 days in presence of IL-2 (400 U/ml) to enhance CXCR6 expression. Overnight stimulation with anti-CD3 mAb+anti-CD28 mAb, which resulted in CD69 induction and cytokine (IL-2 and IFN-gamma) production, reduced cell surface expression of CXCR6 by 85% and that of CCR5 by 76%. The Ca(2+) ionophore, ionomycin (125-500 ng/ml), also markedly diminished CXCR6 expression (85%), but without inducing CD69 expression or cytokine production, and reduced CCR5 expression by only 40%. In contrast, the phorbol esters, PdBu or PMA had little effect on CXCR6 expression (23% reduction) but induced CD69 expression and caused a profound down-regulation (92%) of CCR5 expression. Moreover, CCR7, whose expression was low on CXCR6(+) T cells, was little affected by any of these modes of activation. The down-regulation of CXCR6 expression induced by CD3/CD28 activation was blocked by the broad kinase inhibitor, staurosporine, and by the src kinase inhibitor, PP2, but not by the MEK1 inhibitor, U0106. Most interestingly, the calcineurin inhibitor, FK506, consistently inhibited CD3/CD28-induced CXCR6 down-regulation. FK506 also blocked the decrease of CXCR6 expression caused by ionomycin, whereas staurosporine or PP2 had no effect on this decrease. Altogether, these data indicate that CXCR6 expression is down-regulated, independent of CCR5 or CD69 expression and of cytokine induction, by T cell activation signals that involve predominantly the Ca(2+)-dependent calcineurin pathway.
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PMID:Down-regulation of cell surface CXCR6 expression during T cell activation is predominantly mediated by calcineurin. 1291 53

We evaluated the effects of d-myo-inositol 1,4,5-tris-phosphate on cardiac hypertrophy. d-myo-inositol 1,4,5-tris-phosphate augmented cardiac hypertrophy as evidenced by its effects on DNA synthesis, protein synthesis, and expression of immediate-early genes c-myc and c-fos, beta-myosin heavy chain, and alpha-actin. The administration of d-myo-inositol 1,4,5-tris-phosphate increased the expression of nuclear factor of activated T-cells and cardiac-restricted zinc finger transcription factor (GATA4). Real-time quantitative RT-PCR showed that d-myo-inositol 1,4,5-tris-phosphate-induced GATA4 mRNA was significantly enhanced even in the presence of the calcineurin inhibitor, cyclosporine A. The effect of d-myo-inositol 1,4,5-tris-phosphate was blocked after inhibition of inositol-trisphosphate receptors but not after inhibition of c-Raf/mitogen-activated protein kinase kinase (MEK)/mitogen-activated protein kinase (ERK) or p38 mitogen-activated protein kinase pathways. The study shows that d-myo-inositol 1,4,5-tris-phosphate-induced cardiac hypertrophy is mediated by GATA4 but independent from the calcineurin pathway.
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PMID:GATA4-mediated cardiac hypertrophy induced by d-myo-inositol 1,4,5-tris-phosphate. 1625 52

Although IGF-II activating the IGF-II receptor signaling pathway has been found to stimulate cardiomyocyte hypertrophy, the role of IGF-II in cardiac cell apoptosis remains unclear. This study aimed to identify the roles of IGF-II and/or IGF-II receptors (IGF-II/IIR) in cardiomyoblast apoptosis and in hypertensive rat hearts with abdominal aorta ligation. Cultured rat heart-derived H9c2 cardiomyoblasts and excised hearts from Sprague-Dawley rats with 0- to 20-day complete abdominal aorta ligation, a model of ANG II elevation and hypertension, were used. IGF-II/IIR expression, caspase activity, DNA fragmentation, and apoptotic cells were measured by RT-PCR, Western blot, agarose gel electrophoresis, and TUNEL assay following various combinations of ANG II, IGF-II/IIR antibody, CsA (calcineurin inhibitor), SP-600125 (JNK inhibitor), SB-203580 (p38 inhibitor), U-0126 (MEK inhibitor), or Staurosporine (PKC inhibitor) in H9c2 cells. ANG II-induced DNA fragmentation and TUNEL-positive cells were blocked by IGF-II/IIR antibodies and antisense IGF-II, but not by IGF-II sense. IGF-II-induced apoptosis was blocked by IGF-IIR antibody and CsA. The increased gene expressions of IGF-II and -IIR induced by ANG II were reversed by U-0126 and Sp600125, respectively. Caspase 8 activities induced by ANG II were attenuated by U-0126, SP-600125, and CsA. DNA fragmentation induced by ANG II was totally blocked by SP-600125, and CsA and was attenuated by U-0126. In rats with 0- to 20-day complete abdominal aorta ligation, the increases in IGF-II/IIR levels in the left ventricle were accompanied by hypertension as well as increases in caspase 9 activities and TUNEL-positive cardiac myocytes. ANG II-induced apoptosis was reversed by IGF-II/IIR blockade and coexisted with increased transactivation of IGF-II and -IIR, which are mediated by ERK and JNK pathways, respectively, both of which further contributed to cardiomyoblast apoptosis via calcineurin signaling. The increased cardiac IGF-II, IGF-IIR, caspase 9, and cellular apoptosis were also found in hypertensive rats with abdominal aorta ligation.
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PMID:Roles of insulin-like growth factor II in cardiomyoblast apoptosis and in hypertensive rat heart with abdominal aorta ligation. 1682 5

The biological effects of the Corticotropin-releasing factor (CRF) family of neuropeptides are mediated by mobilization of [Ca(2+)]. Aim of the current work was to examine if the calcineurin/NFAT (nuclear factor of activated T-cells) signaling pathway is involved in the effect of CRF peptides in catecholamine synthesis and secretion from PC12 rat pheochromocytona cells, a model for the study of adrenal catecholamine production. PC12 cells express both types of CRF receptors. Our data are as follows: (a) The calcineurin inhibitor cyclosporine A (CsA) blocked norepinephrine secretion induced by ligands of either CRF type 1 (CRF(1)) or 2 (CRF(2)) receptors on PC12 cells. (b) Silencing NFAT2 expression using a selective NFAT2 siRNA blocked CRF(1) and CRF(2) -induced NE production. (c) CRF ligands induced NFAT transcriptional activity in cells transfected with a luciferase reporter construct controlled by NFAT binding elements (NFAT-Luc). (d) CsA completely blocked the stimulatory effect of CRF(1) and CRF(2) ligands on NFAT activity in NFAT-Luc transfected cells. (e) PKA, PKC, p38-MAPK, Tpl2, Ha-Ras, and AKT1 were crucial intermediates for both CRF(1) and CRF(2)-induced NFAT activation. Interestingly, MEK1/2 and ERK1/2 were crucial only for the CRF(2)-induced NFAT activation. (f) p38-MAPK and Tpl2 were crucial intermediates for both CRF(1) and CRF(2)-induced norepinephrine production, while AKT1 affected only CRF(2)-induced norepinephrine production. In conclusion, our data suggest that CRF(1) and CRF(2) ligands activate the transcription factor NFAT and its activation is prerequisite for CRF-induced catecholamine production from chromaffin cells.
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PMID:The calcineurin-nuclear factor of activated T cells signaling pathway mediates the effect of corticotropin releasing factor and urocortins on catecholamine synthesis. 2170 50

The regulation of cytoplasmic Ca(2+) is crucial for various cellular processes. Here, we examined the cytoplasmic Ca(2+) levels in living fission yeast cells by a highly sensitive bioluminescence resonance energy transfer-based assay using GFP-aequorin fusion protein linked by 19 amino acid. We monitored the cytoplasmic Ca(2+) level and its change caused by extracellular stimulants such as CaCl(2) or NaCl plus FK506 (calcineurin inhibitor). We found that the extracellularly added Ca(2+) caused a dose-dependent increase in the cytoplasmic Ca(2+) level and resulted in a burst-like peak. The overexpression of two transient receptor potential (TRP) channel homologues, Trp1322 or Pkd2, markedly enhanced this response. Interestingly, the burst-like peak upon TRP overexpression was completely abolished by gene deletion of calcineurin and was dramatically decreased by gene deletion of Prz1, a downstream transcription factor activated by calcineurin. Furthermore, 1 hour treatment with FK506 failed to suppress the burst-like peak. These results suggest that the burst-like Ca(2+) peak is dependent on the transcriptional activity of Prz1, but not on the direct TRP dephosphorylation. We also found that extracellularly added NaCl plus FK506 caused a synergistic cytosolic Ca(2+) increase that is dependent on the inhibition of calcineurin activity, but not on the inhibition of Prz1. The synergistic Ca(2+) increase is abolished by the addition of the Ca(2+) chelator BAPTA into the media, and is also abolished by deletion of the gene encoding a subunit of the Cch1-Yam8 Ca(2+) channel complex, indicating that the synergistic increase is caused by the Ca(2+) influx from the extracellular medium via the Cch1-Yam8 complex. Furthermore, deletion of Pmk1 MAPK abolished the Ca(2+) influx, and overexpression of the constitutively active Pek1 MAPKK enhanced the influx. These results suggest that Pmk1 MAPK and calcineurin positively and negatively regulate the Cch1-Yam8 complex, respectively, via modulating the balance between phosphorylation and dyphosphorylation state.
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PMID:Transient receptor potential (TRP) and Cch1-Yam8 channels play key roles in the regulation of cytoplasmic Ca2+ in fission yeast. 2181 7