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)

Leukotriene-C4 synthase (LTC4S; EC 2.5.1.37) catalyzes the committed step in the biosynthesis of the peptidoleukotrienes, which are important in the pathogenesis of asthma. Antibodies were generated to a synthetic peptide based on the partial amino acid sequence previously reported for human LTC4S [Nicholson, D.W., Ali, A., Vaillancourt, J.P., Calaycay, J.R., Mumford, R.A., Zamboni, R.J. & Ford-Hutchinson, A. W. (1993) Proc. Natl. Acad. Sci. USA 90, 2015-2019] and specifically bound detergent-solubilized LTC4S obtained from THP-1 cells, confirming that the published sequence is associated with enzyme activity. Inosine-containing oligonucleotides based on the partial protein sequence were used to isolate a 679-bp cDNA for LTC4S from THP-1 cells. The cDNA contains an open reading frame that encodes a 150-amino acid protein (M(r) = 16,568) that has a calculated pI value of 11.1. The deduced protein sequence is composed predominantly of hydrophobic amino acids; hydropathy analysis predicts three transmembrane domains connected by two hydrophilic loops. Analysis of the deduced sequence identified two potential protein kinase C phosphorylation sites and a potential N-linked glycosylation site. The amino acid sequence for human LTC4S is unique and shows no homology to other glutathione S-transferases. LTC4S was found to be most similar to 5-lipoxygenase activating protein (31% identity, 53% similarity), another protein involved in leukotriene biosynthesis. Active enzyme was expressed in bacterial, insect, and mammalian cells as shown by the biosynthesis of LTC4 in incubation mixtures containing LTA4 and reduced glutathione. The cloning and expression of human LTC4S provide the basis for a better understanding of this key enzyme in peptidoleukotriene biosynthesis.
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PMID:Molecular cloning and expression of human leukotriene-C4 synthase. 793 84

The two tumor necrosis factor (TNF) receptors (TNF-R55 and TNF-R75) can release soluble TNF-binding proteins (TNF-R55-BP and TNF-R75-BP) by proteolytic cleavage. The proteolytic processing of the TNF receptors was investigated in monoblastic THP-1 and promyelocytic HL-60-10 leukemic cell lines. The release of soluble forms of both receptors was rapidly stimulated by staurosporine-sensitive protein kinase C activation by phorbol myristate acetate (PMA) and more slowly stimulated by TNF. No receptor release was seen below a temperature of 16 degrees C. NH4Cl (10 mmol/liter) and monensin (1 mumol/liter), known to increase intracellular pH, inhibited to some extent PMA- and TNF-induced release of both TNF-R55-BP and TNF-R75-BP. The inhibitory effect of monensin might be explained by a diminished translocation of newly synthesized receptor to the plasma membrane. The weak inhibitory effect of NH4Cl on PMA-induced release of soluble receptor forms could be due to effects on a pH-sensitive compartment. PMA-induced down-regulation of receptors was not dependent on acidity as it occurred also in the presence of monensin and NH4Cl when the release of TNF-BPs is partially blocked. Dibutyryl cAMP inhibited the PMA-induced release of TNF-R55-BP but not of TNF-R75-BP in both cell lines investigated. In addition, dibutyryl cAMP alone stimulated the release of both receptors but only in THP-1 cells. Our data show that the generation of soluble forms of both TNF receptors can be regulated by both PKC and PKA.
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PMID:Mechanisms involved in the processing of the p55 and the p75 tumor necrosis factor (TNF) receptors to soluble receptor forms. 794 29

To evaluate ras-mediated signal transduction, we constructed a transient transfection assay system that measures chloramphenicol acetyl transferase activity expressed under the transcriptional-enhancer elements responsive to ras, protein kinase C, and protein kinase A in NIH3T3 cells. Characterization of the assay system with several known activators and inhibitors of signal transduction pathways proved that our system could reliably evaluate agents that affect individual pathways. Pirarubicin ((2"R)-4'-tetrahydropyranyladriamycin, THP), which has recently been found able to reverse ras-transformed cells, appeared to selectively inhibit the ras signal transduction pathway.
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PMID:Use of transcriptional-enhancer elements responsive to ras, protein kinase A and protein kinase C to evaluate inhibitors of specific signal transduction pathways. 795 Nov 37

Lipopolysaccharide (LPS)-induced phospholipase D (PLD) activation was investigated in undifferentiated monocytic leukemic cell lines THP-1 and U-937. Treatment of THP-1 or U-937 cells labelled with [32P]orthophosphate, [32P]acyl GPC or [3H]alkyl GPC with LPS, in the presence of 0.5% ethanol, resulted in the accumulation of labelled phosphatidylethanol (PEt) through PLD activation. LPS-mediated PLD activation of THP-1 or U-937 was inhibited by staurosporine (2 microM) and by protein kinase C (PKC) down-regulation with 12-O-tetradecanoylphorbol 13-acetate (TPA) suggesting a role for PKC. In addition to LPS, TPA, ionomycin and cell-permeant analogs of diacylglycerol also stimulated [3H]PEt accumulation. The TPA-induced PEt accumulation was also completely abolished by staurosporine or down-regulation of PKC (> 95% inhibition). Furthermore, the LPS-mediated [32P]PEt formation was attenuated by either depletion of extracellular Ca2+ with EGTA (5 mM) or chelation of intracellular Ca2+ by BAPTA (30 microM). These results indicate that an increase in intracellular Ca2+ is necessary for LPS-mediated PLD activation. Further support for PKC activation by LPS was obtained by determining PKC activity in an in vitro assay of histone H1 phosphorylation using [gamma-32P]ATP. In untreated THP-1 cells, approximately 64% of the PKC activity was localized in the cytosol and 36% in the membrane fraction. Treatment of the cells with LPS (10 micrograms/ml, for 2 h) resulted in an increase of 10% of the membrane-associated PKC activity and a corresponding decrease in the cytosol fraction. These data provide evidence that one of the mechanisms of LPS-mediated signal transduction in human monocytic cell lines involves activation of PLD.
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PMID:Lipopolysaccharide-mediated signal transduction through phospholipase D activation in monocytic cell lines. 801 74

An eosinophilic substrain of HL-60 cells (HL-60#7) predominantly synthesized cysteinyl leukotrienes after stimulation with the calcium ionophore A23187. Activation of protein kinase C (PKC) by phorbol 12-myristate 13-acetate (PMA) specifically attenuated cysteinyl leukotriene production without affecting the biosynthesis of non-cysteinyl leukotrienes. The inhibition of cysteinyl leukotriene biosynthesis was prevented only by specific PKC inhibitors (staurosporine and bisindolylmaleimide) but not by inhibitors of tyrosine kinases (genistein, tyrphostin 47, and herbimycin A), protein kinase A (KT5720), or the oxidative burst (apocynin). Similar results were obtained when LTC4 synthase enzymatic activity was measured directly in the presence of saturating concentrations of exogenously added substrates. Therefore, the inhibitory effects of PKC activation on cysteinyl leukotriene formation in intact cells was attributable to effects on the LTC4 synthase enzyme. The mechanism of inhibition of LTC4 synthase by PKC activation was determined by kinetic analysis to be noncompetitive in both eosinophil-like HL-60#7 cells and monocytic THP-1 cells. Contrary to the effect of PKC activation on cysteinyl leukotriene biosynthesis, the formation of prostaglandin E2 and thromboxane B2 was elevated twofold to threefold after PMA treatment, which was prevented by the PKC inhibitor, staurosporine. We propose a regulatory model in which PKC activation shifts the profile of eicosanoid mediators produced by eosinophils from cysteinyl leukotrienes to prostanoids.
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PMID:Activation of protein kinase C down-regulates leukotriene C4 synthase activity and attenuates cysteinyl leukotriene production in an eosinophilic substrain of HL-60 cells. 802 12

The tumor necrosis factor alpha (TNF-alpha) promoter contains an AP-1/CRE-like binding site, TGAGCTCA. AP-1 elements generally transduce signals involving protein kinase C; the CRE site mediates a cAMP response, involving protein kinase A. Thus, this element has the potential to receive signals through divergent signaling pathways. Nuclear protein binding studies using extracts from THP-1 monocytic cells treated with lipopolysaccharide (LPS), which stimulates, or dexamethasone (Dex) or pentoxifylline (PTX), which inhibit TNF production, respectively, suggest that two low-mobility complexes could be involved in regulation through this promoter region. PTX and Dex increase binding of both these complexes compared with untreated cells; approximately 2 hours after LPS induction, the upper complex becomes undetectable. This upper complex is composed of ATF2 (activating transcription factor 2, a cyclic AMP responsive element binding protein) homodimers; the lower is a heterodimer of jun/ATF2. LPS induces c-jun and thus may enhance formation of jun/ATF2 complexes, which could be activating complexes. In this case, the simultaneous presence of both complexes, which would occur in the presence of Dex or PTX, could reduce the amount of TNF transcription through competitive binding. Through in vitro competitive binding studies comparing the binding affinities of the TNF promoter sequence and a consensus CRE, we further suggest how variation of endogenous binding sequences from consensus may be an important property for regulatory control of particular genes.
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PMID:Interaction of nuclear proteins with an AP-1/CRE-like promoter sequence in the human TNF-alpha gene. 802 67

We examined the signal transduction mechanism responsible for the gamma interferon-induced indoleamine 2,3-dioxygenase (IDO) gene expression in a human monocytic cell line, THP-1. Our results suggest that gamma interferon-induced activation of protein tyrosine kinase is a prerequisite for gene expression and that activation of protein kinase C and another unknown signal(s), both of which are transduced by the protein tyrosine kinase, synergistically induce IDO gene expression. Neither Ca2+ influx nor cyclic nucleotide-dependent kinases were suggested to be involved in the signaling pathway.
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PMID:The signal transduction mechanism responsible for gamma interferon-induced indoleamine 2,3-dioxygenase gene expression. 811 68

We attempted to study the role of protein tyrosine kinase (PTK) and protein kinase C (PKC) in the cascade of phosphorylation of ribosomal protein S6 during differentiation of leukemic cells (HL-60, THP-1, and RWLeu-4). Neither activation nor inhibition of colony stimulating factor-1 (CSF-1) receptor's PTK activity with CSF-1 or genistein respectively affected the phosphorylation of S6. However, vanadate which is a protein tyrosine phosphatase (PTP) inhibitor showed enhancement of S6 phosphorylation. Dimethylsulfoxide which does not affect either PTK or PKC demonstrated no change in S6 phosphorylation. PKC activation by acute 12-0-tetradecanoyl phorbol-13-acetate (TPA) treatment induced monocytic differentiation and S6 phosphorylation. Surprisingly, the more prominent phosphorylation of S6 protein was observed in PKC-depleted cells by prolonged TPA treatment. Our results suggest that PTK/PTP play a lesser role in S6 phosphorylation of HL-60 cells than PKC does. In addition, two different mechanisms seem to be involved in TPA-induced S6 phosphorylation during HL-60 differentiation: PKC activation by acute TPA treatment and PKC depletion which may lead to the synthesis of some endogenous protein responsible for the differentiation by chronic TPA treatment.
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PMID:Phosphorylation of ribosomal protein S6 and its regulation during differentiation of human leukemic cells. 817 29

The protein kinase C activators phorbol 12-myristate 13-acetate (PMA) and mezerein induce differentiation of human monocytic leukemia (THP-1) cells along the monocyte/macrophage pathway of development. The differentiated cells express many important macrophage functions including phagocytosis and the secretion of immunomodulatory cytokines. Mezerein-differentiated THP-1 cells secrete interleukin-1 beta as well as a tumor cell growth inhibitory factor whose basal level is increased in response to interferon-gamma. However, tumoricidal, as opposed to tumoristatic, activity of differentiated THP-1 has not been documented. We report herein that PMA-differentiated THP-1 cells (PD/THP-1) contain elevated levels of MHC class I and class II mRNAs even in the absence of activating factors, and kill HT-29 human colon carcinoma cells when stimulated with recombinant human interferon-gamma. These two characteristics are important components of the macrophage phenotype. The results presented in this study extend previous observations on THP-1 cells by demonstrating that PD/THP-1 cells display a critical, immunologically relevant macrophage function, and therefore, enhance the utility of THP-1 as a model for the in vitro study of immunomodulatory drugs and macrophage-mediated cytocidal processes.
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PMID:Phorbol myristate acetate-differentiated THP-1 cells display increased levels of MHC class I and class II mRNA and interferon-gamma-inducible tumoricidal activity. 839 66

The protein kinase C (PKC) activating phorbol esters are known to prevent the decay of mRNA of several cytokines and proto-oncogenes. To examine whether the phorbol ester signal is continuously required for this stabilizing effect, THP-1 monocytic cells were stimulated either with phorbol 12,13-dibutyrate (PDBu), which can be removed from the cells by washings, or with the more hydrophobic phorbol 12-myristate 13-acetate (PMA). Both of these stimuli induced high levels of interleukin-1 beta (IL-1 beta) mRNA. When the cells were washed at the peak of the IL-1 beta mRNA expression, this mRNA decayed rapidly in the PDBu stimulated cells while in PMA stimulated cells the mRNA levels were not affected. Moreover, this mRNA degradation induced by the removal of PDBu could be inhibited by readdition of the phorbol ester. This restabilization could be prevented by pharmacologic inhibitors of PKC, but not by inhibiting protein or RNA synthesis. Thus these data suggest that the phorbol ester must be continuously present to exert its mRNA stabilizing effect and that its effect is PKC-mediated but does not require active protein or RNA synthesis.
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PMID:Continuous presence of phorbol ester is required for its IL-1 beta mRNA stabilizing effect. 841 17


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