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

The effect of anti-neutrophil cytoplasm autoantibodies (ANCA) on neutrophil activation was studied by pre-incubating neutrophils with IgG and F(ab')2 prepared from ANCA patients with Wegener's granulomatosis or microscopic polyarteritis. We measured the generation of inositol triphosphate (IP3) (a product of hydrolysis of membrane phospholipid which acts as a second intracellular messenger), and the translocation of protein kinase C (PKC) upon stimulation by a chemotactic peptide, fMet-Leu-Phe (fMLP). ANCA+ F(ab')2 did not induce a significant increase in IP3 generation. Nonetheless, ANCA+ F(ab')2 and ANCA+ IgG pretreatment of human neutrophils reduced the production of inositol phosphates upon subsequent fMLP stimulation compared with experiments performed when cells were pretreated with F(ab')2 and IgG prepared from ANCA- healthy subjects. A significantly reduced generation of IP3 and inositol biphosphate (IP2) was observed. ANCA+ F(ab')2 pretreatment of neutrophils inhibited fMLP-stimulated IP3 generation in a dose-dependent manner. The membrane-bound PKC activity upon stimulation by FMLP and PMA was reduced in neutrophils pretreated with ANCA+ F(ab')2 and IgG. These results indicate that ANCA affect in vitro signal transduction (IP3 generation, and translocation of PKC) in human neutrophils. Apparently, further activation of signal transduction by chemotactic peptide is significantly blunted in cells pre-incubated with ANCA+ F(ab')2 but not with F(ab')2 from healthy controls.
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PMID:The effect of anti-neutrophil cytoplasm autoantibodies on the signal transduction in human neutrophils. 189 20

The role of membrane potential (Em) on the initiation of DNA synthesis in murine macrophage cell line PU5-1.8 was investigated with fluorescent probes bis-oxonol and diS-C3-(5). Incubation of PU5-1.8 cells in high K(+)-HEPES buffer or with gramicidin at 37 degrees C for 1h that depolarized the membrane induced [3H]-thymidine incorporation and expression of early response gene such as c-myc and c-fos. When PU5-1.8 cells were treated with a number of agents including fetal calf serum (FCS), lipopolysaccharide (LPS), epidermal growth factor (EGF), N-formyl-methionyl-leucyl-phenylalanine (FMLP) and bradykinin (BK), only FCS caused DNA synthesis and membrane depolarization. Other agents had no effect on these events. The FCS-mediated DNA synthesis in PU5-1.8 cells was inhibited by clamping the membrane potential with valinomycin. Moreover, intracellular alkalinization induced by nigericin at pH 7.9, which is believed to be a permissive signal for mitogenesis, caused membrane depolarization. On the other hand, challenge of cells with phorbol 12-myristate 13 acetate (PMA) suppressed the K(+)-mediated DNA synthesis. However, the treatment of cells with PMA did not change the membrane potential but suppressed the gramicidin-mediated membrane depolarization. These observations suggest that there is a correlation between membrane depolarization and initiation of DNA synthesis in PU5-1.8 cells. PKC may be acting as a modulator in this transducing pathway.
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PMID:Membrane depolarization was required to induce DNA synthesis in murine macrophage cell line PU5-1.8. 194 52

Neutrophils produce reactive oxygen species (superoxide anion [O2-]) via activation of reduced nicotinamide dinucleotide phosphate oxidase. In the intact neutrophil, this enzyme can be activated by increases in cytosolic calcium, protein kinase C, and unsaturated fatty acids such as arachidonic acid, all of which are produced on stimulation by chemotactic peptides like N-formyl-methionyl-leucyl-phenylalanine. Cytokines such as granulocyte-macrophage colony-stimulating factor (GM-CSF) do not stimulate the respiratory burst but instead prime the cell for an enhanced response by an appropriate stimulus. We examined the role and potential mechanisms of free fatty acids in stimulating or priming neutrophil O2- production. Except for arachidonic acid, the ability of an unsaturated fatty acid to stimulate O2- production was not correlated with its critical micellar concentration, suggesting that detergent action was not the primary mechanism. Eicosatetraynoic acid, which blocks further arachidonate metabolism by the 5- and 15-lipoxygenases, inhibited O2- production by arachidonic acid. However, eicosatetraenoic acid did not inhibit other unsaturated fatty acid or phorbol ester-induced O2- production, suggesting that the effects of arachidonic acid were mediated at least in part by a metabolite. The same negatively charged, unsaturated fatty acids that directly stimulated O2- production when used in micromolar concentrations also primed neutrophils when added in nanomolar concentrations. The amount of a priming response was independent of chain length or number of double bonds. The magnitude of priming observed in GM-CSF-treated cells could be reconstituted with combinations of arachidonic acid and its lipoxygenase products.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Unsaturated fatty acids and lipoxygenase products regulate phagocytic NADPH oxidase activity by a nondetergent mechanism. 194 May 76

The characteristics of the activation of a histone H4 kinase activity in Triton X-100 lysates of rabbit peritoneal neutrophils pretreated with fMet-Leu-Phe were studied: The activation of the kinase was a) inhibited by the antagonist of formylpeptide, t-Boc-(Phe-Leu)2(-)-Phe, b) completely inhibited by pertussis toxin pretreatment, c) not affected by the pretreatment of neutrophils with an activator of protein kinase C, phorbol-12-myristate-13-acetate, or an inhibitor of protein kinase C, 1-(5-isoquinoline-sulfonyl)-2-methyl-piperazine, and d) not inhibited in the cells preloaded with the intracellular calcium chelators, bis-(o-aminophenoxy)-ethane-N,N,N',N'-tetra acetic acid acetoxymethyl-ester (BAPTA/AM). These results suggest that the stimulus-induced activation of H4 kinase requires functional receptor and GTP-binding protein but neither calcium mobilization nor protein kinase C activation.
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PMID:Stimulation of a histone H4 protein kinase in Triton X-100 lysates of rabbit peritoneal neutrophils pretreated with chemotactic factors: lack of requirements of calcium mobilization and protein kinase C activation. 196 52

Platelet-activating factor is a potent proinflammatory lipid mediator which directly stimulates neutrophil chemotaxis, degranulation, aggregation, and superoxide radical (O2-) production. PAF also modifies or 'primes' neutrophil responses to other agents. Although a relatively weak direct oxidative agonist, PAF markedly enhances O2- release evoked by phorbol myristate acetate (PMA) and the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (FMLP), increasing the maximal rate of O2- production by a calcium-dependent mechanism. PAF also increases protein kinase activity in the membrane fraction of neutrophils. In search of a mechanism for oxidative priming by PAF, we investigated the role of PAF in modifying PMA-induced activation/translocation of protein kinase C (PKC) in human neutrophils. In the presence of PAF and PMA both PKC and calcium-, phospholipid-independent protein kinase activities in particulate fractions increase markedly over activities detected in the presence of PMA alone. The increase in particulate protein kinase activities requires the presence of cytochalasin B and is calcium-dependent. The PKC-enhancing effect of PAF may be involved in the mechanism whereby the phospholipid 'primes' neutrophils for augmented oxidative responses to some stimuli but the exact role of PKC in neutrophil oxidative metabolism remains to be defined.
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PMID:Priming of neutrophil oxidative responses by platelet-activating factor. 196 14

Maturation of human myeloid cells is associated with quantitative and qualitative changes in protein kinase C (PKC) and increases in N-formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP) receptors, actin, and actin regulatory proteins. We have studied the actin responses and cell shape changes caused by FMLP and its second messenger pathways in HL60 cells undergoing neutrophilic maturation. In uninduced cells, the PKC activators 12-O-tetradecanoyl phorbol-13-acetate (TPA), bryostatin, and 1-oleyl-2-acetylglycerol (OAG) resulted in 15% to 30% decreases in F-actin, whereas FMLP had no effect. Ionomycin had no effect on actin but did cause a 10-fold increase in intracellular calcium. Cells grown for 24 hours in 1% dimethyl sulfoxide (DMSO) acquired the ability to polymerize actin in response to FMLP and ionomycin. TPA continued to cause a decrease in F-actin at 24 hours, but caused an increase in F-actin at 48 to 72 hours of maturation. The PKC inhibitor 1-5-isoquinolinesulfonyl 2-methylpiperazine (H7) partially blocked the F-actin increase caused by TPA in induced cells, but had no effect on the decrease in F-actin caused by TPA in uninduced cells or the increase in F-actin seen in FMLP-treated neutrophils. F-actin rich pseudopods developed following TPA or FMLP stimulation of induced HL60 cells; in uninduced cells neither agent caused pseudopod formation but TPA caused a dramatic loss of surface ruffles. The ability of FMLP and ionomycin to elicit a neutrophil-like actin response in HL60 cells within 24 hours after DMSO treatment shows that the actin regulatory mechanism is mature by that time. The inability of ionomycin to increase F-actin in uninduced cells supports the view that calcium increases alone are insufficient for actin polymerization. The longer maturation time required for HL60 cells to develop an actin polymerization response to TPA compared with FMLP, coupled with the inability of H7 to block the FMLP-mediated F-actin increase in neutrophils, suggests that the F-actin increase caused by FMLP is not mediated solely by PKC. Lastly, the TPA-induced F-actin decrease and shape changes in uninduced HL60 cells, and the longer time required for a "mature" response to TPA, may reflect immaturity in the PKC isoenzyme pattern rather than immaturity of the actin regulatory mechanism.
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PMID:Signal transduction and the regulation of actin conformation during myeloid maturation: studies in HL60 cells. 198 1

Human neutrophils have been labeled in 1-O-alkyl-phosphatidylcholine with 3H in both the alkyl chain and the choline moiety. Upon stimulation of these labeled cells with formyl-Met-Leu-Phe, C5a, or phorbol 12-myristate 13-acetate, phospholipase D is activated to produce 1-O-[3H]alkylphosphatidic acid ([3H]alkyl-PA) and [3H]choline. The [3H]alkyl-PA is then dephosphorylated by phosphatidate phosphohydrolase (PPH) to produce 1-O-[3H]alkyldiglyceride ([3H]alkyl-DG). Sphingosine, a sphingoid base known to inhibit protein kinase C (PKC), causes a dose-dependent inhibition of [3H]alkyl-DG formation. This inhibition is accompanied by increased accumulation of [3H]alkyl-PA without alterations in [3H]choline formation. Studies using various other sphingoid bases demonstrate that a long hydrocarbon chain and an amino group are required for the inhibition of DG formation. These results suggest that sphingoid bases inhibit PPH activity without altering phospholipase D activation and that they exhibit a similar structure-activity relationship for both PPH and PKC. K252a, a PKC inhibitor which acts by competing for ATP binding sites, does not inhibit the formation of [3H]alkyl-DG, [3H]alkyl-PA, or [3H]choline at a concentration (3 microM) that completely blocks phorbol 12-myristate 13-acetate-induced protein phosphorylation. Moreover, in neutrophil homogenates, sphingosine but not octylamine, inhibits PPH activity in a dose-dependent manner. Thus sphingosine inhibits PPH activity by a PKC-independent mechanism, raising the possibility that sphingoid bases may play a role in regulating PPH-mediated lipid metabolism in stimulated cells.
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PMID:Sphingosine inhibits phosphatidate phosphohydrolase in human neutrophils by a protein kinase C-independent mechanism. 198 67

X-irradiation and the phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA) act in a synergistic manner to increase the yield of transformed C3H10T1/2 cells in vitro. TPA modulated both translocation from the cytosol to the plasma membrane, and down regulation of protein kinase C (PKC) after prolonged (48 h) TPA exposure. N-tosyl-L-phenylalanine chloromethyl ketone (TPCK), antipain, and soybean-derived Bowman-Birk inhibitor, protease inhibitors that suppress transformation of C3H10T1/2 cells, had no effect on these TPA-mediated alterations of PKC activity, suggesting that protease inhibitors suppress TPA-stimulated promotion in vitro via a PKC-independent pathway. Several experiments were performed to determine whether non-toxic concentrations of the PKC inhibitors, N-p-tosyl-L-lysine chloromethyl ketone (TLCK), TPCK, N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7), or 1-(5-isoquinoline-sulfonyl)-2-methyl-piperazine (H-7), modulated the movement of cells from a quiescent state into the cell cycle. TPCK and the combination of H-7 and W-7 lowered DNA synthesis when cells were stimulated to divide by TPA. Because other protease inhibitors that slow transformation in vitro did not have the same suppressive effect on DNA synthesis, the inhibitory pathway that suppresses carcinogenic activity is likely to be different from the suppression of DNA synthesis.
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PMID:Suppression of phorbol ester-enhanced radiation-induced malignancy in vitro by protease inhibitors is independent of protein kinase C. 201 16

Neutrophils possess a classical Ca2+, phosphatidyl serine (PS) and diglyceride (DG)-dependent protein kinase C (beta-PKC) which was translocatable from cytosol to membrane in response to elevated Ca2+ in the physiologic range or to pretreatment with phorbol myristate acetate (PMA). The translocatable beta-PKC was purified from neutrophil membranes prepared in the presence of Ca2+, eluted with EGTA and subjected to hydroxyapatite chromatography. An 80-kDa protein possessing Ca/DG/PS-dependent histone phosphorylating activity was recognized by a monoclonal antibody to beta-PKC but not to alpha-PKC or gamma-PKC. A cytosolic kinase activity remaining after Ca(2+)-induced translocation of beta-PKC was dependent on PS and DG but did not require Ca2+. This novel Ca(2+)-independent, PS/DG-dependent kinase, termed nPKC, eluted from hydroxyapatite between alpha-PKC and beta-PKC, ran as a 76-kDa band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and was reactive to a polyclonal consensus antibody but not to monoclonal antibodies to alpha-PKC, beta-PKC, or gamma-PKC. Long chain fatty acyl-CoA, but not the corresponding free fatty acids, inhibited nPKC in the 1-10 microM range. The chemotactic peptide fMet-Leu-Phe triggered prompt but transient increases in neutrophil long chain fatty acid acyl-CoA, suggesting that nPKC is regulated by fatty acyl-CoA as well as DG during neutrophil activation. Purified beta-PKC phosphorylated a number of cytosolic proteins in a Ca(2+)-dependent manner, including a major 47-kDa cytosolic protein, which may be implicated in superoxide anion generation. In contrast, nPKC did not phosphorylate the 47-kDa protein, but phosphorylated numerous cytosolic proteins in a Ca(2+)-independent manner, including a 66-kDa protein which was not phosphorylated by beta-PKC. Differences in location, substrate specificity, and cofactor dependence between nPKC and beta-PKC suggest these kinases may play selective roles in the activation sequence of the neutrophil.
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PMID:Protein kinase C isotypes and signaling in neutrophils. Differential substrate specificities of a translocatable calcium- and phospholipid-dependent beta-protein kinase C and a phospholipid-dependent protein kinase which is inhibited by long chain fatty acyl coenzyme A. 202 25

To determine the contribution of phosphate acceptor substrate to the pattern of activity of calcium-dependent, phospholipid-sensitive protein kinase (protein kinase C, PKC), we assayed cytosolic and particulate PKC activity for histone, troponin, myosin light chain (MLC), and endogenous cellular proteins in human neutrophils stimulated with phorbol myristate acetate (PMA), the chemotactic peptide n-formyl-methionyl-leucyl-phenylalanine (FMLP) and synergistic stimulation with both agonists. In general, phosphotransferase activity in neutrophil subfractions toward troponin and endogenous proteins paralleled that toward histone, but MLC was a poor substrate for PKC and the pattern of phosphotransferase activity differed from that seen with the other substrates. Furthermore, the phosphorylation of endogenous neutrophil cytosolic proteins increased significantly after stimulation with FMLP, suggesting an endogenous cytosolic substrate(s) which increased in concentration following stimulation. We conclude that histone is a useful phosphate acceptor for study of PKC activity in human neutrophils, but substrate variability occurs and may influence interpretation of results in assays of PKC activity.
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PMID:Substrate dependence of human neutrophil protein kinase C. 205 46


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