Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P05412 (c-Jun)
 11,453 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Extracellular signal-regulated kinase (ERK)-dependent phosphorylation is an important regulator for cytosolic phospholipase A(2) (cPLA(2)). In this study, we found that the protein synthesis inhibitor cycloheximide can potentiate thapsigargin-induced arachidonic acid (AA) release concomitant with ERK phosphorylation from murine RAW 264.7 macrophages. The cycloheximide effect is not due to the activation of p38 mitogen-activated protein kinase (MAPK) nor c-Jun NH(2)-terminal kinase (JNK), because the activator of both MAPKs anisomycin does not elicit AA release. Cycloheximide effect is additive to the tyrosine phosphatase inhibitor orthovanadate since these two stimuli induced sustained ERK activation respectively through inhibition of the translation and activity of MAPK phosphatase-1 (MKP-1).
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PMID:Cycloheximide-induced cPLA(2) activation is via the MKP-1 down-regulation and ERK activation. 1098 80

In this study, we evaluated the effects of pervanadate, a tyrosine phosphatase inhibitor, on the regulation and function of heat-shock factor 1 (HSF1) in HeLa cells. We showed that 50-100 microM pervanadate induced the hyperphosphorylation of the latent HSF1, as demonstrated by a retarded mobility of the HSF1 protein in SDS-polyacrylamide gel electrophoresis and as supported by the reversal of this mobility shift upon treatment of the cell extract with acid phosphatase. Pervanadate by itself had no effect on the monomeric stoichiometry and DNA-binding activity of HSF1. Upon heat shock, the pervanadate-induced hyperphosphorylated HSF1 formed DNA-binding trimers and translocated into the nuclear compartment. At high concentration (approximately 500 microM), pervanadate also induced the tyrosine phosphorylation of many cellular proteins and blunted the heat-induced transcription of hsp 70. N-acetyl cysteine inhibited these effects of pervanadate, suggesting a redox-based mechanism for its activity. Analysis of the activation of mitogen-activated protein kinases (MAPKs) using antibodies specific for the phospho-form (activated) of the kinases in Western blot showed that pervanadate activated extracellular signal-regulated kinase (ERK1/2), c-Jun-N-terminal kinase 1/2 (JNK1/2), and p-38 kinase. Pharmacological inhibitors of the ERK1/2 kinase pathway or the p38 kinase had little or no effect on the pervanadate-induced hyperphosphorylation of HSF1. Our results show that hyperphosphorylation of hHSF1 can occur prior to and independent of other events involved in the activation of hHSF1. The possibility that activation of the MAPK signaling cascade, notably JNK, may contribute to the hyperphosphorylation of human HSF1 (hHSF1) is discussed.
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PMID:Pervanadate induces the hyperphosphorylation but not the activation of human heat shock factor 1. 1105 5

The previously cloned rat nerve growth factor-regulated G protein-coupled receptor NRG-1 (Glickman, M., Malek, R. L., Kwitek-Black, A. E., Jacob, H. J., and Lee N. H. (1999) Mol. Cell. Neurosci. 14, 141-52), also known as EDG-8, binds sphingosine-1-phosphate (S1P) with high affinity and specificity. In this paper we examined the signal transduction pathways regulated by the binding of S1P to EDG-8. In Chinese hamster ovary cells heterologously expressing EDG-8, S1P inhibited forskolin-induced cAMP accumulation and activated c-Jun NH2-terminal kinase. Surprisingly, S1P inhibited serum-induced activation of extracellular regulated protein kinase 1 and 2 (ERK1/2). Treatment with pertussis toxin, which ADP-ribosylates and inactivates G(i), blocked S1P-mediated inhibition of cAMP accumulation, but had no effect on c-Jun NH2-terminal kinase activation or inhibition of ERK1/2. The inhibitory effect of S1P on ERK1/2 activity was abolished by treatment with orthovanadate, suggesting the involvement of a tyrosine phosphatase. A subunit selective [35S] guanosine 5'-3-O-(thio)triphosphate binding assay demonstrates that EDG-8 activated G(i/o) and G12 but not Gs and G(q/11) in response to S1P. In agreement, EDG-8 did not stimulate phosphoinositide turnover or cAMP accumulation. The ability of S1P to induce mitogenesis in cells expressing the EDG-1 subfamily of G protein-coupled receptors is well characterized. In contrast, S1P inhibited proliferation in Chinese hamster ovary cells expressing EDG-8 but not empty vector. The antiproliferative effect, like S1P-mediated ERK1/2 inhibition, was orthovanadate-sensitive and pertussis toxin-insensitive. Our results indicate that EDG-8, a member of the EDG-1 subfamily, couples to unique signaling pathways.
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PMID:Nrg-1 belongs to the endothelial differentiation gene family of G protein-coupled sphingosine-1-phosphate receptors. 1106 96

Shp-2, a src homology (SH)2-containing phosphotyrosine phosphatase, appears to be involved in cytoplasmic signaling downstream of a variety of cell surface receptors, although the mechanism is unclear. Here, we have determined a role of Shp-2 in the cytokine circuit for inflammatory and immune responses. Production of interleukin (IL)-6 in response to IL-1 alpha or tumor necrosis factor (TNF)-alpha was nearly abolished in homozygous mutant (Shp-2(-/)-) fibroblast cells. The targeted Shp-2 mutation has no significant effect on the activation of the three types of mitogen-activated protein (MAP) kinases, extracellular signal-regulated kinase (Erk), c-Jun NH(2)-terminal kinase (Jnk), and p38, by IL-1/TNF, indicating that Shp-2 does not work through MAP kinase pathways in mediating IL-1/TNF-induced IL-6 synthesis. In contrast, IL-1/TNF-stimulated nuclear factor (NF)-kappa B DNA binding activity and inhibitor of kappa B (I kappa B) phosphorylation was dramatically decreased in Shp-2(-/)- cells, while the expression and activity of NF-kappa B-inducing kinase (NIK), Akt, and I kappa B kinase (IKK) were not changed. Reintroduction of a wild-type Shp-2 protein into Shp-2(-/)- cells rescued NF-kappa B activation and IL-6 production in response to IL-1/TNF stimulation. Furthermore, Shp-2 tyrosine phosphatase was detected in complexes with IKK as well as with IL-1 receptor. Thus, this SH2-containing enzyme is an important cytoplasmic factor required for efficient NF-kappa B activation. These results elucidate a novel mechanism of Shp-2 in cytokine signaling by specifically modulating the NF-kappa B pathway in a MAP kinase-independent fashion.
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PMID:Modulation of the nuclear factor kappa B pathway by Shp-2 tyrosine phosphatase in mediating the induction of interleukin (IL)-6 by IL-1 or tumor necrosis factor. 1113 24

In the blast crisis phase of chronic myelogenous leukemia (CML), Bcr-Abl(+) myeloblasts fail to undergo terminal maturation. The extracellular signal-regulated kinase (Erk) mitogen-activated protein (MAP) kinase has been shown to mediate terminal differentiation of myeloid cells. Interestingly, Bcr-Abl(+) CML cell lines established from blast crisis were found to have low Erk MAP kinase activity. In this study, we analyzed the role of the Gab2 docking protein in regulation of the Erk MAP kinase in Bcr-Abl(+) K562 human CML cells. Overexpression of Gab2 in K562 cells resulted in transcriptional activation of the c-fos serum response element (SRE) promoter, whereas overexpression of SHP2, Grb2, and CrkL had no effect. Activation of the c-fos SRE transcriptional activity by Gab2 required tyrosine 604, which is a SHP2 docking site on Gab2, and the SHP2 tyrosine phosphatase activity. Elk1, c-Jun, and CHOP trans-reporting assays indicated that overexpression of Gab2 selectively activated the Erk2-Elk1 signaling pathway. To determine cellular consequences of elevating the Gab2 level in K562 cells, stable cell lines for doxycycline-inducible expression of the wild-type Gab2 (Gab2WT) and an SHP2-binding defective Gab2 (Gab2Tyr604Phe) were established. Analysis of these cell lines indicated that induction of Gab2WT expression, but not Gab2Tyr604Phe expression, led to Erk activation, growth arrest, cell spreading, and enlargement; expression of megakaryocyte/platelet lineage-specific integrins alphaIIb/beta3 (CD41/CD61); and upregulation of RNA for megakaryocyte/platelet proteins. All of these changes are characteristics of megakaryocytic differentiation. Together, these results reveal Gab2 as a limiting signaling component for Erk MAP kinase activation and terminal differentiation of K562 CML cells.
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PMID:Regulation of the Erk2-Elk1 signaling pathway and megakaryocytic differentiation of Bcr-Abl(+) K562 leukemic cells by Gab2. 1183 Apr 91

It has been shown that glutathione S-transferase pi (GSTpi) interacts with and suppresses the activity of c-Jun NH(2)-terminal kinase (JNK). GST-deficient mice (GSTpi(-/-)) have higher levels of circulating white blood cells, with similar proportions of lymphocytes, monocytes, and granulocytes. Interestingly, a selective expansion of splenic B lymphocytes was observed in GSTpi(-/-) animals but no change in T lymphocytes or natural killer cells. A peptidomimetic inhibitor of GSTpi that disrupts the interaction between GSTpi and JNK mimics in wild type mice the increased myeloproliferation observed in GSTpi(-/-) animals. Until now, the molecular basis for this effect has not been defined. In an in vitro hematopoiesis assay, interleukin-3, granulocyte colony-stimulating factor, and granulocyte/macrophage colony-stimulating factor were more effective at stimulating proliferation of hematopoietic cells in GSTpi(-/-) mice than in wild type. The JNK inhibitor SP600125 which caused little inhibition of cytokine-induced myeloproliferation in wild type mice, decreased the number of colonies in GSTpi(-/-) animals. A more sustained phosphorylation of the STAT family of proteins was also observed in GSTpi(-/-) bone marrow-derived mast cells exposed to interleukin-3. This was associated with an increased proliferation and a down-regulation of expression of negative regulators of the Janus kinase-STAT pathway SHP, Src homology 2 domain-containing tyrosine phosphatase-1 and -2. The increased activation of JNK and STATs in GSTpi-deficient mice provides a viable mechanism for the increased myeloproliferation in these animals. These data also confirm the important role that GSTpi plays in the regulation of cell signaling pathways in a myeloproliferative setting.
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PMID:Increased myeloproliferation in glutathione S-transferase pi-deficient mice is associated with a deregulation of JNK and Janus kinase/STAT pathways. 1468 49

The function of insulin receptor substrate-1 (IRS-1), a key molecule of insulin signaling, is modulated by phosphorylation at multiple serine/threonine residues. Phorbol ester stimulation of cells induces phosphorylation of two inhibitory serine residues in IRS-1, i.e. Ser-307 and Ser-318, suggesting that both sites may be targets of protein kinase C (PKC) isoforms. However, in an in vitro system using a broad spectrum of PKC isoforms (alpha, beta1, beta2, delta, epsilon, eta, mu), we detected only Ser-318, but not Ser-307 phosphorylation, suggesting that phorbol ester-induced phosphorylation of this site in intact cells requires additional signaling elements and serine kinases that link PKC activation to Ser-307 phosphorylation. As we have observed recently that the tyrosine phosphatase Shp2, a negative regulator of insulin signaling, is a substrate of PKC, we studied the role of Shp2 in this context. We found that phorbol ester-induced Ser-307 phosphorylation is reduced markedly in Shp2-deficient mouse embryonic fibroblasts (Shp2-/-) whereas Ser-318 phosphorylation is unaltered. The Ser-307 phosphorylation was rescued by transfection of mouse embryonic fibroblasts with wild-type Shp2 or with a phosphatase-inactive Shp2 mutant, respectively. In this cell model, tumor necrosis factor-alpha-induced Ser-307 phosphorylation as well depended on the presence of Shp2. Furthermore, Shp2-dependent phorbol ester effects on Ser-307 were blocked by wortmannin, rapamycin, and the c-Jun NH2-terminal kinase (JNK) inhibitor SP600125. This suggests an involvement of the phosphatidylinositol 3-kinase/mammalian target of rapamycin cascade and of JNK in this signaling pathway resulting in IRS-1 Ser-307 phosphorylation. Because the activation of these kinases does not depend on Shp2, it is concluded that the function of Shp2 is to direct these activated kinases to IRS-1.
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PMID:Shp2 is required for protein kinase C-dependent phosphorylation of serine 307 in insulin receptor substrate-1. 1605 40

Somatostatin is a multifunctional hormone that modulates cell proliferation, differentiation and apoptosis. Mechanisms for somatostatin-induced apoptosis are at present mostly unsolved. Therefore, we investigated whether somatostatin receptor subtype 2 (sst2) induces apoptosis in the nontransformed murine fibroblastic NIH3T3 cells. Somatostatin receptor subtype 2 expression induced an executioner caspase-mediated apoptosis through a tyrosine phosphatase SHP-1 (Src homology domain phosphatase-1)-dependent stimulation of nuclear factor kappa B (NF-kappaB) activity and subsequent inhibition of the mitogen-activated protein kinase JNK. Tumor necrosis factor alpha (TNFalpha) stimulated both NF-kappaB and c-Jun NH2-terminal kinase (JNK) activities, which had opposite action on cell survival. Importantly, sst2 sensitized NIH3T3 cells to TNFalpha-induced apoptosis by (1) upregulating TNFalpha receptor protein expression, and sensitizing to TNFalpha-induced caspase-8 activation; (2) enhancing TNFalpha-mediated activation of NF-kappaB, resulting in JNK inhibition and subsequent executioner caspase activation and cell death. We have here unraveled a novel signaling mechanism for a G protein-coupled receptor, which directly triggers apoptosis and crosstalks with a death receptor to enhance death ligand-induced apoptosis.
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PMID:Novel synergistic mechanism for sst2 somatostatin and TNFalpha receptors to induce apoptosis: crosstalk between NF-kappaB and JNK pathways. 1664 35

The overall goal of this study was to determine the molecular basis by which mixed-lineage kinase 3 (MLK3) kinase and its signaling pathways are negatively regulated by the pro-survival Akt pathway in cerebral ischemia. We demonstrated that tyrosine phosphorylation of the phosphatase and tensin homolog deleted on chromosome 10 (PTEN) underlies the increased Akt-Ser473 phosphorylation by orthovanadate. Co-immunoprecipitation analysis revealed that endogenous Akt physically interacts with Rac1 in the hippocampal CA1 region, and this interaction is promoted on tyrosine phosphatase inhibition. The elevated Akt activation can deactivate MLK3 by phosphorylation at the Ser71 residue of Rac1, a small Rho family of guanidine triphosphatases required for MLK3 autophosphorylation. Subsequently, inhibition of c-Jun N-terminal kinase 3 (JNK3) results in decreased serine phosphorylation of 14-3-3, a cytoplasmic anchor of Bax, and prevents ischemia-induced mitochondrial translocation of Bax, release of cytochrome c and activation of caspase 3. At the same time, the expression of Fas-ligand decreases in the CA1 region after inhibition of c-Jun activation. The neuroprotective effect of Akt activation is significant in the CA1 region after global cerebral ischemia. Our results suggest that the activation of the pro-apoptotic MLK3/JNK3 cascade induced by ischemic stress can be suppressed through activation of the anti-apoptotic phosphatidylinositol 3-kinase/Akt pathway, which provides a direct link between Akt and the family of stress-activated kinases.
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PMID:Akt inhibits MLK3/JNK3 signaling by inactivating Rac1: a protective mechanism against ischemic brain injury. 1683 Nov 94

The effects of 2-naphthylethyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline (THI 53), on nitric oxide (NO) production and inducible nitric-oxide synthase (iNOS) protein induction by lipopolysaccharide (LPS) were investigated in RAW 264.7 cells and mice. In cells, THI 53 concentration dependently reduced NO production and iNOS protein induction by LPS. In addition, THI 53 inhibited NO production and iNOS protein induction in LPS-treated mice. LPS-mediated iNOS protein induction was inhibited significantly by the specific tyrosine kinase inhibitor alpha-cyano-(3-hydroxy-4-nitro)cinnamonitrile (AG126) as well as by THI 53. In addition, a c-Jun NH(2)-terminal kinase (JNK) inhibitor anthra[1,9-cd]pyrazole-6 (2H)-one) (SP600125) but not an extracellular regulated kinase inhibitor [2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one (PD98029)] or a p38 inhibitor [4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole (SB230580)] reduced the iNOS protein level induced by LPS. Moreover, a Janus kinase 2 (JAK2) inhibitor alpha-cyano-(3,4-dihydroxy)-N-benzylcinnamide (AG490) dose-dependently prevented LPS-mediated iNOS protein induction. LPS activated phosphorylations of tyrosine kinases, especially tyrosine kinase 2 (Tyk2) and signal transducer and activator of transcription-1 (STAT-1); these were reduced by THI 53. LPS also phosphorylated the JNK pathway; however, this phosphorylation was unaffected by THI 53. Interestingly, a JNK inhibitor (SP600125) and another tyrosine kinase inhibitor (genistein) significantly inhibited STAT-1 phosphorylation, suggesting that the LPS-activated JNK pathway and a tyrosine kinase pathway (especially Tyk2) may link to the STAT-1 pathway, which is involved in iNOS induction. However, THI 53 regulates LPS-mediated iNOS protein induction by affecting the Tyk2/JAK2-STAT-1 pathway, not the JNK pathway. The inhibition by THI 53 of LPS-induced NO production was recovered by a tyrosine phosphatase inhibitor (Na(3)VO(4)), which supports the possibility that THI 53 inhibits the LPS-induced inflammatory response through regulation of tyrosine kinase pathways. THI 53 also inhibited LPS-mediated interferon (IFN)-beta production and nuclear factor-kappaB (NF-kappaB) activation. Thus, THI 53 may regulate LPS-mediated inflammatory response through both the NF-kappaB and IFN-beta/Tyk2/JAK2-STAT-1 pathways.
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PMID:Regulation of lipopolysaccharide-induced inducible nitric-oxide synthase expression through the nuclear factor-kappaB pathway and interferon-beta/tyrosine kinase 2/Janus tyrosine kinase 2-signal transducer and activator of transcription-1 signaling cascades by 2-naphthylethyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline (THI 53), a new synthetic isoquinoline alkaloid. 1710 35


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