Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.13 (protein kinase C)
 49,245 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have previously shown that granulocyte-macrophage colony-stimulating factor (GM-CSF) gene expression induced by interleukin-1 (IL-1) and tumor necrosis factor-alpha (TNF-alpha) in the murine stromal cell line +/+.1-LDA 11 involves activation of phospholipase A2 (PLA2). Furthermore, induction of GM-CSF gene expression due to release of arachidonic acid as a result of PLA2 activation was mediated by the transcriptional factor c-jun. In the present study, we have investigated the potential mechanism involved in the induction of c-jun gene expression by arachidonic acid. Arachidonic acid induced transcription of c-jun mRNA. Downregulation of protein kinase C (PKC) by chronic exposure of stromal cells to the phorbol ester 12-O-tetradecanoyl-phorbol-13-acetate (TPA; 400 nmol/L) did not effect c-jun expression induced by arachidonate. Moreover, pretreatment of cells with the PKC inhibitor, calphostin C (1 mumol/L), caused a marked decrease of c-jun expression induced by TPA, but had no influence on c-jun expression induced by arachidonate. To explore the hypothesis that a tyrosine kinase signalling pathway, independent of PKC activation, was involved in arachidonate-induced c-jun expression, stromal cells were pretreated with the protein tyrosine kinase inhibitor, genistein, before challenge with arachidonic acid. Arachidonate 50 mumol/L)-induced c-jun expression was inhibited, in a dose- and time-dependent manner, by genistein. Genistein similarly inhibited c-jun expression in stromal cells exposed to IL-1 (500 U/mL) plus TNF-alpha (500 U/mL). The potential role of a tyrosine kinase pathway in arachidonate-mediated c-jun expression was further investigated by assaying the tyrosine kinase activity of cells challenged with arachidonic acid, IL-1, and TNF-alpha. Exposure of stromal cells to arachidonic acid induced a 2.1-fold increase in intracellular tyrosine kinase activity determined by phosphorylation of the synthetic peptide, raytide, in the presence of [gamma-32P]-ATP. Similarly, IL-1 and TNF-alpha induced 1.7- and 2.4-fold increases in tyrosine protein kinase activity, respectively. The effect of arachidonic acid on tyrosine kinase activity was inhibited by genistein and was enhanced by sodium vanadate. The increase of protein tyrosine kinase activity detected in arachidonate-stimulated cells was associated, in a dose- and time-dependent fashion, with tyrosine phosphorylation of 240-, 40-, and 29-kD substrates. These results are consistent with the hypothesis that a tyrosine phosphorylation process is triggered by arachidonate as an early event in the signalling pathway that leads to increased expression of c-jun.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Arachidonic acid induces c-jun gene expression in stromal cells stimulated by interleukin-1 and tumor necrosis factor-alpha: evidence for a tyrosine-kinase-dependent process. 757 89

1-O-Octadecyl-2-O-methyl-rac-glycero-3-phosphocholine (ET-18-OCH3) is a synthetic diether phospholipid that is competitive with phosphatidylserine binding to the regulatory domain of protein kinase C (PKC). Our previous studies indicate that the selective inhibition of tumor cell growth by ET-18-OCH3 may be due to altered signal transduction mechanisms, including the inhibition of PKC. To further define the mechanism of action of ET-18-OCH3, we have used it to study the role of PKC in regulation of the transcription factor NF-kappa B, which is activated by diverse stimuli. In the 293.27.2 human kidney cell line, as in hematopoietic cells of all lineages, NF-kappa B is stimulated by 12-O-tetradecanoylphorbol-13-acetate (TPA), tumor necrosis factor-alpha (TNF-alpha), and interleukin-1 alpha (IL-1 alpha). The response to either TNF-alpha or IL-1 alpha is synergistically enhanced by TPA. However, the regulatory mechanisms and signal transduction systems responsible for NF-kappa B activation in response to these different stimuli have not been determined in detail. We have used ET-18-OCH3 and auranofin, which inhibit PKC by different mechanisms, to assess the role of PKC in NF-kappa B activation. ET-18-OCH3 markedly inhibits TPA-induced NF-kappa B activation, as measured by HIV long terminal repeat-directed expression of beta-galactosidase. The IC50 for inhibition by ET-18-OCH3 is approximately 2 microM, a noncytotoxic concentration. Inhibition of TPA-induced NF-kappa B activation was dependent upon preincubation with ET-18-OCH3, and the drug was active at approximately 2 mol% of total cellular phospholipid. ET-18-OCH3 did not inhibit NF-kappa B activation by either TNF-alpha or IL-1 alpha, indicating that there are multiple distinct signal transduction pathways leading to activation of NF-kappa B. We have confirmed these results using auranofin, an antirheumatic drug that is a specific PKC inhibitor interacting with the catalytic domain. Like ET-18-OCH3, auranofin blocked NF-kappa B activation by TPA but not by TNF-alpha or IL-1 alpha. Also like the ether lipid, auranofin only partially blocked the synergy exhibited by TPA and TNF-alpha. To confirm the role of NF-kappa B in this response, we measured NF-kappa B by electrophoretic mobility shift assay. Both ET-18-OCH3 and auranofin inhibited cellular induction of the active NF-kappa B complex in response to TPA but not in response to TNF-alpha.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:ET-18-OCH3 inhibits nuclear factor-kappa B activation by 12-O-tetradecanoylphorbol-13-acetate but not by tumor necrosis factor-alpha or interleukin 1 alpha. 758 18

Reactive oxygen intermediates (e.g., superoxide [O2-]) generated by microglia may play a role in host defense and injury within the central nervous system. We investigated the effect of cytokines on human microglial cell O2- production on stimulation with phorbol myristate acetate. Priming of microglial cell cultures with interferon-gamma or tumor necrosis factor-alpha resulted in a dose- and time-dependent enhancement of O2- production. The priming effects of these cytokines were mediated through a protein kinase C signal transduction pathway. In contrast, astrocytes did not generate detectable O2- on phorbol myristate acetate stimulation. Treatment of microglia with transforming growth factor-beta, interleukin-4, or interleukin-10 suppressed in a dose-dependent manner the priming effects of tumor necrosis factor-alpha and interferon-gamma. The results of this study have implications for understanding the mechanisms by which cytokines and microglia contribute to processes of host defense and neurodegeneration via generation of reactive oxygen intermediates.
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PMID:Modulation of human microglial cell superoxide production by cytokines. 761 8

The effect of the tumor promoter 4 beta-phorbol 12-myristate 13-acetate and of the phosphatases inhibitor okadaic acid on the binding of tumor necrosis factor-alpha (TNF-alpha) to a human osteogenic sarcoma cell line (Saos-2) was investigated. Both substances prevented almost completely TNF binding to its receptors. The effect of 4 beta-phorbol 12-myristate 13-acetate was reversed by the protein kinase C inhibitors staurosporine and calphostin C or by protein kinase C depletion. Vinblastine, under conditions causing full microtubule disassembly, produced only a 50% decrease of TNF binding. Vinblastine plus PMA was additive in fully preventing TNF binding. It is suggested that the degree of binding of TNF-alpha to its receptors in Saos-2 cells is under the control of a microtubule-dependent and of a microtubule-independent regulatory pathway.
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PMID:Regulation of the TNF-alpha receptor in human osteosarcoma cells: role of microtubules and of protein kinase C. 767 25

The mRNAs coding for interleukin-1 alpha (IL-1 alpha) and IL-1 beta are constitutively transcribed but do not accumulate in human diploid fibroblasts and in fibrosarcoma cells. Treatment of these cells with tumor necrosis factor (TNF) induces accumulation of IL-1 mRNA by an unknown mechanism. This induction of IL-1 mRNA was investigated in HT-1080 cells. The induction was quite fast, with maximum levels of IL-1 alpha and beta mRNA reached 4 h after addition of TNF. Nuclear run-off experiment showed that TNF did not increase the rate of transcription of IL-1 mRNA. This mRNA was apparently unstable in untreated cells, but it accumulated in cycloheximide-treated cells. Phorbol esters induced IL-1 mRNA, suggesting that activation of protein kinase C was responsible for the accumulation of this mRNA. This hypothesis was confirmed by experiments with the PKC inhibitors staurosporine and calphostin C, which prevented the induction of IL-1 mRNA by TNF and accelerated the decay of this mRNA in cells pretreated with TNF. Both IL-1 alpha and IL-1 beta were detected in TNF-treated cells by Western blot analysis and enzyme-linked immunosorbent assay. These results indicate that the TNF-mediated induction of IL-1 can be entirely accounted for by stabilization of this mRNA.
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PMID:Tumor necrosis factor increases stability of interleukin-1 mRNA by activating protein kinase C. 768 Oct 61

Receptor-mediated superoxide (O2-.)-generation in human peripheral neutrophils (HPPMN) is enhanced by various priming agents, such as granulocyte colony stimulating factor (G-CSF) and tumor necrosis factor (TNF-alpha). We previously reported that this enhancement occurred in parallel with the priming agent-induced increase in protein tyrosyl phosphorylation which is sensitive to tyrosine kinase (TK) inhibitors [Akimaru K. et al. Arch. Biochem. Biophys. 298:703, 1992]. We describe here that nonsteroidal anti-inflammatory drugs (NSAIDs) such as indomethacin and aspirin, modulate the priming and tyrosine phosphorylation of HPPMN. The enhancement by TNF-alpha of formylmethionyl-leucyl-phenylalanine (FMLP)-induced O2-. generation was not inhibited by 5 microM azide, whereas that of FMLP-induced luminol chemiluminescence (LCL) was sensitive. Enhancement of FMLP-induced O2-. generation and LCL by priming agents was inhibited by both aspirin and indomethacin in a concentration dependent manner. This inhibition by the NSAIDs was much stronger than that for FMLP-induced O2-. generation without priming. The half-inhibition dose of indomethacin and aspirin were 50 microM and 1.5 mM, respectively. The priming-induced enhancement of tyrosyl phosphorylation of some neutrophil proteins, such as that of 108 and 115 kDa, was also inhibited by aspirin and indomethacin in a dose-dependent manner. However, dose dependent inhibition of the enhanced O2-. generation by the NSAIDs was not completely similar to that of enhanced tyrosyl phosphorylation. However, PKC-mediated O2-. generation, which has little sensitivity to TNF-alpha or G-CSF, was rather stimulated by the NSAIDs. These findings suggest that aspirin and indomethacin inhibit also the early steps of neutrophil activation as reflected by their ability to inhibit priming and the related tyrosyl phosphorylation of neutrophil proteins.
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PMID:Effect of indomethacin and aspirin on the TNF-alpha-induced priming and protein tyrosyl phosphorylation of human neutrophils. 768 97

A protein kinase C (PKC) agonist selective for the beta I isozyme, 12-deoxyphorbol 13-phenylacetate 20-acetate (dPPA), induced NF-kappa B-like binding activity and surface expression of E-selectin and VCAM-1 in human umbilical vein endothelial cells (HUVEC), similar to the effects of tumor necrosis factor-alpha (TNF-alpha). Induction of E-selectin and VCAM-1 expression by dPPA was completely inhibited by the PKC inhibitors staurosporine and Ro31-7549. The PKC inhibitors also reduce TNF-alpha-induced VCAM-1 expression. However, neither dPPA nor TNF-alpha translocated PKC from the cytosolic to the plasma or nuclear membrane particulate fractions in HUVEC. These results indicate that activation of the beta I PKC isozyme is sufficient for expression of E-selectin and VCAM-1, and suggest that PKC may mediate the effects of TNF-alpha and dPPA without requiring the translocation normally associated with activation of PKC.
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PMID:A protein kinase C agonist, selective for the beta I isozyme, induces E-selectin and VCAM-1 expression on HUVEC but does not translocate PKC. 768 53

The role of protein kinase C (PKC) in interleukin-1 beta- (II-1 beta)-, tumor necrosis factor-alpha- (TNF-alpha)-, and lipopolysaccharide- (LPS)-induced vascular cell adhesion molecule-1 (VCAM-1) expression on human umbilical vein endothelial cells (HUVEC) was studied. PKC inhibition or downregulation diminished VCAM-1 mRNA accumulation and protein expression. Interleukin-1 beta, TNF-alpha, and LPS induce nuclear factor (NF)-kappa B-like binding activity, which precedes VCAM-1 transcription. PKC inhibition did not prevent NF-kappa B-like binding activity, indicating that this is PKC-independent, and NF-kappa B-like binding activity is insufficient for transcription of VCAM-1.
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PMID:The role of protein kinase C in the induction of VCAM-1 expression on human umbilical vein endothelial cells. 769 Jul 17

The transepithelial paracellular permeability of an epithelium formed by LLC-PK1 cells increases upon activation of protein kinase C (PKC) by the phorbol ester tumor promoter, TPA, or in response to the cytokine tumor necrosis factor-alpha (TNF). Until recently, however, we have not been able to inhibit the permeability effects of TPA or TNF using any of the currently available serine-threonine kinase inhibitors. In this study we report the treatment of epithelial cell sheets with the selective PKC inhibitor bisindolylmaleimide, GF109203X, completely prevents the TPA-induced but not the TNF-alpha induced increase in tight junction permeability. While PKC-alpha still translocates from the cytosol to the membrane of TPA-stimulated epithelial cells overall PKC activity in the membrane fraction is markedly reduced in the presence of GFX.
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PMID:The protein kinase C inhibitor, bisindolylmaleimide, inhibits the TPA-induced but not the TNF-induced increase in LLC-PK1 transepithelial permeability. 773 36

Bacterial lipopolysaccharide (LPS) can elicit septic shock; however, there is growing evidence that most of its pathophysiological effects are mediated by the release of tumor necrosis factor (TNF) and other cytokines. In turn, LPS-induced TNF production is thought to implicate the activation of intracellular protein kinase C (PKC). In this study, we examined whether pH-sensitive liposomes containing staurosporine (STP), a potent inhibitor of PKC, when injected intravenously would suppress TNF production and reduce mortality in an endotoxin rat model. We found that pretreatment of rats with pH-sensitive STP-liposomes by intravenous administration 1.5 h prior to LPS injection decreased lethality from 80% to approximately 30%. Importantly, this improvement in outcome was associated with significant reductions in TNF serum levels; 1 h after LPS injection serum TNF was 73% lower than in a saline control group, and at 2 h TNF levels were 84% lower. STP-liposome pretreatment also ameliorated the severe reduction in body temperature, characteristic for a hypodynamic shock, that was observed in LPS-challenged rats, but had relatively little effect on the transient leukopenia. We conclude that STP-liposomes can suppress LPS-induced TNF production by the mononuclear phagocytic system, can reduce the symptoms of septic shock, and can increase survival.
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PMID:Staurosporine encapsulated into pH-sensitive liposomes reduces tnf production and increases survival in rat endotoxin shock. 773 68


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