Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P51812 (mitogen-activated protein)
 10,636 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The pleiotropic cytokine tumor necrosis factor-alpha (TNF alpha) controls the expression of multiple gene products in macrophages and plays an important role in host defense. TNF alpha is recognized by the receptors, CD120a (p55) and CD120b (p75). Ligation of CD120a (p55) by TNF alpha or by anti-receptor agonistic antibodies initiates signal transduction leading to the activation of mitogen-activated protein kinases (MAPKs) (p42mapk/erk2 and p44mapk/erk1). Phosphorylation and activation of MAPK are mediated by MAPK kinase (MEK), a family of Thr/Tyr kinases. In this study, we investigated the preferential involvement of the MEK isoforms MEK1 and MEK2 in the activation of p42mapk/erk2 in mouse macrophages stimulated with TNF alpha. Exposure of macrophages to TNF alpha stimulated a time-dependent increase in the activity of MEK1 as measured by an in vitro kinase assay using kinase-inactive p42mapk/erk2 (rMAPKkd) as substrate in the presence of gamma-[32P]ATP. Maximal activation of MEK1 was detected at 10 min poststimulation and coincided with maximal transphosphorylation of Tyr and Thr residues of rMAPKkd. By contrast, there was no evidence of MEK2 activation in macrophages in response to TNF alpha. These data suggest that MEK1 is the preferred substrate for MEK kinase, the upstream kinase implicated in activation of the MAPK pathway in macrophages by TNF alpha.
 ...
PMID:Preferential involvement of MEK1 in the tumor necrosis factor-alpha-induced activation of p42mapk/erk2 in mouse macrophages. 749 90

Tumor necrosis factor alpha (TNF alpha) activates the stress-activated protein kinases (SAPKs, also known as Jun nuclear kinases or JNKs) resulting in the stimulation of AP-1-dependent gene transcription and induces the translocation of NF kappa B to the nucleus resulting in the stimulation of NF kappa B-dependent gene transcription. A potential second messenger for these signaling pathways is ceramide, which is generated when TNF alpha activates sphingomyelinases. We show that treatment of HL-60 human promyelocytic cells with exogenous sphingomyelinase leads to rapid stimulation of JNK/SAPK activity, an effect not mimicked by treatment with phospholipase A2, C, or D. Further, JNK/SAPK activity is stimulated 2.7- and 2.8-fold, respectively, in cells exposed to C2-ceramide (5 microM) or TNF alpha (10 ng/ml). The prolonged stimulation of this kinase activity by C2-ceramide is similar to that previously reported for TNF alpha. In contrast, the related mitogen-activated protein kinases ERK1 and ERK2 are weakly stimulated following TNF alpha treatment (1.5-fold) and are inhibited by C2-ceramide treatment. TNF alpha also potently stimulates NF-kappa B DNA binding activity and transcriptional activity, but these effects are not mimicked by addition of C2-ceramide or sphingomyelinase to intact cells. Furthermore, TNF alpha, sphingomyelinase, and C2-ceramide induce c-jun, a gene that is stimulated by the ATF-2 and c-Jun transcription factors. These data suggest that ceramide may act as a second messenger for a subset of TNF alpha's biochemical and biological effects.
 ...
PMID:Ceramide activates the stress-activated protein kinases. 755 90

Interleukin 1 (IL1) activated mitogen-activated protein (MAP) kinase kinase in human gingival and foreskin fibroblasts and KB cells. Maximal activity was found in cytosolic extracts made after stimulating cells for 15 min. On anion-exchange chromatography two differently charged forms of MAP kinase kinase were identified, both phosphorylated a kinase-defective mutant MAP kinase, and activated recombinant wild type MAP kinase to phosphorylate MBP. Both were inhibited by an antiserum to recombinant MAP kinase kinase and the less acidic form was identified on Western blotting as an antigen of approximately 43 kDa. Indistinguishable forms were very much more strongly induced by phorbol myristate acetate (PMA). TNF had a similar effect to that of IL1.
 ...
PMID:Interleukin 1 and tumour necrosis factor activate the mitogen-activated protein (MAP) kinase kinase in cultured cells. 769 14

The early growth response 1 (EGR-1) gene is induced by mitogenic and differentiating signals in diverse cell types. The present studies have examined the effects of TNF-alpha on the induction of EGR-1 expression in human myeloid leukemia cells and the potential cytoplasmic signaling cascades that transduce TNF-induced signals to the nucleus. The results demonstrate that treatment of HL-60 cells with TNF is associated with the transient induction of the EGR-1 gene. The results also demonstrate that TNF treatment is associated with activation of the serine/threonine kinase, pp90rsk, which acts upstream to EGR-1 gene induction. Partial purification of pp90rsk by affinity chromatography demonstrated an increase in S6 peptide phosphorylation in response to TNF treatment. Because TNF activates sphingomyelin hydrolysis, we also studied the effects of sphingomyelinase (SMase) on induction of EGR-1 and pp90rsk. The results demonstrate that SMase also activates pp90rsk and induces EGR-1 gene expression. Previous work has demonstrated that mitogen-activated protein (MAP) kinase activates pp90rsk. The present studies further show that treatment with TNF or SMase is associated with induction of both the pp42/44 MAP and the related Jun kinases. Induction of pp42/44 MAP kinase activity is temporally related to activation of pp90rsk and the EGR-1 gene. These findings support the involvement of an MAP kinase/pp90rsk/EGR-1 cascade in the response of myeloid leukemia cells to TNF.
 ...
PMID:Activation of serine/threonine protein kinases and early growth response 1 gene expression by tumor necrosis factor in human myeloid leukemia cells. 770 52

The purpose of these studies was to determine the intracellular signal transduction pathways of bacterial products in murine macrophages from lipopolysaccharide (LPS)-responder C3H/HeN and LPS-nonresponder C3H/HeJ mice. Both LPS and synthetic lipopeptide CGP 31362 (LPP) induced production of tumor necrosis factor alpha (TNF-alpha) in C3H/HeN macrophages. In C3H/HeJ macrophages, however, TNF-alpha was induced only by incubation with LPP. Both LPS and LPP induced tyrosine phosphorylation on proteins with apparent molecular masses of 39, 41, and 45 kD (p35, p41, and p45) in C3H/HeN macrophages, whereas in C3H/HeJ macrophages, tyrosine phosphorylation was induced only by LPP. 20-h incubation with LPS or LPP downregulated TNF-alpha production/secretion and tyrosine phosphorylation in C3H/HeN macrophages induced by additional LPS or LPP. In C3H/HeJ macrophages, however, the downregulation of TNF-alpha production and tyrosine phosphorylation were observed only with LPP. Protein kinase assays, Western blotting analyses, phenyl-Sepharose chromatography, and immunocomplex kinase assay suggested that p45 and p39 were similar or identical to mitogen-activated protein (MAP) kinase 1 and 2, respectively. Pretreatment of macrophages with LPS or LPP did not change the amount of kinase proteins but inhibited the stimulation of kinase activity by the agents. These data suggest that MAP kinases are among target proteins involved in the transduction of LPS and LPP signals that lead to activation of murine macrophages to produce/secrete TNF.
 ...
PMID:Tyrosine phosphorylation of mitogen-activated protein kinases is necessary for activation of murine macrophages by natural and synthetic bacterial products. 838 52

In our previous studies (Refs. 1 and 2), it was shown that protein tyrosine kinase (PTK) inhibitors, radicicol and herbimycin A, inhibit the expression of the mitogen-inducible cyclooxygenase (COX-2) and proinflammatory cytokines. Radicicol and herbimycin A possess polarized double bonds which can conjugate sulphydryl groups of proteins. Parthenolide, the predominant sesquiterpene lactone in European feverfew (Tanacetum parthenium), contains alpha-methylene-gamma-lactone (MGL) and an epoxide in its structure. These moieties can interact with biological nucleophiles such as a sulfhydryl group. Parthenolide inhibited the expression of COX-2 and proinflammatory cytokines (TNF alpha and IL-1) in lipopolysaccharide (LPS)-stimulated macrophages. The structure-function relationship indicates that the MGL moiety confers the inhibitory effect. Parthenolide suppressed LPS-stimulated protein tyrosine phosphorylation in the murine macrophage cell line (RAW 264.7). This suppression was correlated with its inhibitory effect on the expression of COX-2 and the cytokines. Among tyrosine phosphorylated proteins, mitogen-activated protein kinases (MAPKs) exhibited the most dramatic inhibition.
 ...
PMID:Inhibition of the expression of inducible cyclooxygenase and proinflammatory cytokines by sesquiterpene lactones in macrophages correlates with the inhibition of MAP kinases. 883 94

Previous studies suggested that tyrosine kinase activation is an important signal transduction event in the IL-1 response of chondrocytes. The present study identifies the mitogen-activated protein (MAP) kinases extracellular signal-regulated kinase (ERK)-1 and ERK-2 as major tyrosine phosphorylated proteins in IL-1 stimulated chondrocytes. Kinase assays on immunoprecipitates with myelin basic protein as substrate showed that ERK-1 and ERK-2 activation was detectable within 5 min after IL-1 stimulation and decreased to baseline within 60 min. Analysis of other members of the MAP kinase family showed that chondrocytes also express c-Jun NH2 terminal kinase (JNK)-1, JNK-2, and p38 proteins. These kinases were time-dependently activated by IL-1. Among other chondrocyte activators tested, only TNF activated all three of the MAP kinase subgroups. JNK and p38 were not activated by any of the other cytokines and growth factors tested. However, ERK was also activated by PDGF, IGF-1, and IL-6. Phorbol 12-myristate 13-acetate, calcium ionophore, and cAMP analogues only increased ERK activity but had no significant effects on JNK or p38. These results suggest differential activation of MAP kinase subgroups by extracellular stimuli. ERK is activated in response to qualitatively diverse extracellular stimuli and various second messenger agonists. In contrast, JNK and p38 are only activated by IL-1 or TNF, suggesting that these kinases participate in the induction of the catabolic program in cartilage.
 ...
PMID:Selective activation of the mitogen-activated protein kinase subgroups c-Jun NH2 terminal kinase and p38 by IL-1 and TNF in human articular chondrocytes. 894 62

The death domain of the type 1 tumor necrosis factor receptor (TNFR1) mediates interactions with several proteins involved in signaling the downstream effects of TNF. We have used the yeast interaction trap to isolate a protein, MADD, that associates with the death domain of TNFR1 through its own C-terminal death domain. MADD interacts with TNFR1 residues that are critical for signal generation and coimmunoprecipitates with TNFR1, implicating MADD as a component of the TNFR1 signaling complex. Importantly, we have found that overexpression of MADD activates the mitogen-activated protein (MAP) kinase extracellular signal-regulated kinase (ERK), and expression of the MADD death domain stimulates both the ERK and c-JUN N-terminal kinase MAP kinases and induces the phosphorylation of cytosolic phospholipase A2. These data indicate that MADD links TNFR1 with MAP kinase activation and arachidonic acid release and provide further insight into the mechanisms by which TNF exerts its pleiotropic effects.
 ...
PMID:MADD, a novel death domain protein that interacts with the type 1 tumor necrosis factor receptor and activates mitogen-activated protein kinase. 911 75

The immunostimulant tumor necrosis factor-alpha (TNF alpha), produced by monocytes/macrophages in response to inflammatory disorders, regulates gene expression in part through induction of mitogen-activated protein kinases (MAPKs), including the stress-activated protein kinase (SAPK) (c-Jun N-terminal kinase [JNK]) and the extracellular signal-regulated kinases (ERKs). In testicular Leydig cells, the induction of steroidogenesis by cAMP is inhibited by TNF alpha. To examine the potential mechanisms governing the mutual inhibition between cAMP and TNF alpha in Leydig cells, the intracellular signaling pathways that contribute to AP-1-dependent gene expression were examined in the mouse MA-10 Leydig cell line. TNF alpha induced SAPK activity sixfold at 15 min, and the PKC inhibitor calphostin C reduced the induction of SAPK by 30%. cAMP induced SAPK activity twofold but reduced TNF alpha-induced SAPK activity. ERK activity was inhibited by both cAMP and TNFa. TNFa increased c-Jun protein, but only weakly induced FOS proteins (c-Fos, FosB, Fra-1, and Fra-2) whereas cAMP increased the abundance of several FOS proteins (c-Fos, FosB, Fra-1, and Fra-2), with little effect on c-Jun levels. AP-1 binding activity, assessed using electrophoretic mobility shift assays, was increased twofold by TNF alpha and fivefold by cAMP. Cyclic AMP alone induced AP-1-responsive reporter (p3TPLUX) activity threefold after 2 h with peak effect of 4-fold at 4 hr. AP-1 reporter was not induced by TNF alpha alone but in the presence of cAMP, TNF alpha induced AP-1 reporter activity 12-fold. In conclusion, TNF alpha and cAMP induce distinct components that separately contribute to the modulation of AP-1 activity in MA-10 cells.
 ...
PMID:The effect of tumor necrosis factor-alpha and cAMP on induction of AP-1 activity in MA-10 tumor Leydig cells. 936 89

A pleiotropic cytokine, tumor necrosis factor-alpha (TNF alpha), regulates the expression of multiple macrophage gene products and thus contributes a key role in host defense. In this study, we have investigated the specificity and mechanism of activation of members of the c-Jun-NH2-terminal kinase/stress-activated protein kinase (JNK/SAPK) subfamily of mitogen-activated protein kinases (MAPKs) in mouse macrophages in response to stimulation with TNF alpha. Exposure of macrophages to TNF alpha stimulated a preferential increase in catalytic activity of the p46 JNK/SAPK isoform compared with the p54 JNK/SAPK isoform as determined by: (i) separation of p46 and p54 JNK/SAPKs by anion exchange liquid chromatography and (ii) selective immunodepletion of the p46 JNK/SAPK from macrophage lysates. To investigate the level of regulation of p46 JNK/SAPK activation, we determined the ability of MKK4/SEK1/JNKK, an upstream regulator of JNK/SAPKs, to phosphorylate recombinant kinase-inactive p46 and p54 JNK/SAPKs. Endogenous MKK4 was able to transphosphorylate both isoforms. In addition, both the p46 and p54 JNK/SAPK isoforms were phosphorylated on their TPY motif in response to TNF alpha stimulation as reflected by immunoblotting with a phospho-specific antibody that recognizes both kinases. Collectively, these results suggest that the level of control of p46 JNK/SAPK activation is distal not only to MKK4 but also to the p54 JNK/SAPK. Preferential isoform activation within the JNK/SAPK subfamily of MAPKs may be an important mechanism through which TNF alpha regulates macrophage phenotypic heterogeneity and differentiation.
 ...
PMID:Preferential activation of the p46 isoform of JNK/SAPK in mouse macrophages by TNF alpha. 937 18


1 2 3 4 5 6 7 8 9 10 Next >>