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)

The human m1 (hm1) and m2 (hm2) muscarinic cholinergic receptors (mAChR) expressed in Sf9 insect cells using recombinant baculovirus were tested for their ability to undergo agonist-dependent phosphorylation and desensitization. The muscarinic agonist carbachol induced phosphorylation of the hm2 mAChR in the Sf9 cells incubated with 32P(i) to an extent of 4-5 mol of phosphate/mol of receptor. In contrast, no phosphorylation of the hm1 mAChR was observed. The hm2 mAChR stimulated [35S]GTP gamma S binding to, and GTPase activity of, the insect cell G-proteins. These receptor-mediated activities were reduced by 50% in membranes prepared from agonist-treated cells compared to control, suggesting that the agonist-induced phosphorylation of the hm2 mAChR resulted in desensitization of the receptors. No role for protein kinase C or cyclic nucleotide-dependent kinases in receptor phosphorylation and desensitization was suggested from studies using agents known to modulate the activity of these enzymes. However, pertussis toxin was found to completely eliminate the interaction of the hm2 receptors with the insect cell G-proteins, but did not perturb the ability of carbachol to induce agonist-dependent phosphorylation of the receptors. These results suggested that G-proteins and/or G-protein-activated signalling were not necessary for the agonist-induced phosphorylation of the receptors. Overall, the data indicated that the human m2 (but not the human m1) mAChR expressed in Sf9 insect cells undergo phosphorylation and desensitization in an agonist-dependent, G-protein-independent fashion by an endogenous insect cell kinase. The results demonstrated that a human G-protein-linked receptor is regulated in insect cells in a manner that is similar to that involving members of the G-protein receptor-kinase family.
 ...
PMID:Agonist-induced phosphorylation and desensitization of human m2 muscarinic cholinergic receptors in Sf9 insect cells. 142 77

Electropermeabilized neutrophils were used to study the exocytotic response in rabbit neutrophils. Enzyme release from electropermeabilized neutrophils could be induced by elevating the Ca2+ concentration. Ca(2+)-induced secretion was significantly enhanced by guanosine 5'-[gamma-thio]triphosphate (GTP[S]) in a concentration-dependent manner. The effect of GTP[S] could be blocked by guanosine 5'-[beta-thio]diphosphate (GDP[S]) and was not affected by pertussis toxin. GTP[S] did not induce enzyme release in the absence of Ca2+. Induction of an exocytotic response did not require addition of ATP. However, neutrophils permeabilized in the absence of ATP became refractory to stimulation due to a reduction in their affinity for Ca2+. Responsiveness to the effectors Ca2+ or Ca2+ + GTP[S] could be prolonged or restored by ATP. ATP was not the only agent that prolonged responsiveness; other nucleotides and inorganic phosphates were also effective. The protein kinase C inhibitors staurosporine and 1-O-hexadecyl-2-methyl-sn-glycerol did not inhibit exocytosis and had only a small effect on the prolongation and restoration of responsiveness by ATP. A hypothesis is presented suggesting that the loss of responsiveness is caused by dephosphorylation and that the restoration or prolongation of responsiveness is not mediated by protein kinase C. It is possible that an as yet unidentified Ca(2+)-binding protein is dephosphorylated, resulting in a decrease in Ca2+ affinity.
 ...
PMID:Exocytosis in electropermeabilized neutrophils. Responsiveness to calcium and guanosine 5'-[gamma-thio]triphosphate. 144 33

We have examined the possible involvement of pertussis toxin (PT)-sensitive GTP-binding protein and protein kinase C (PKC) in mitogen-induced tyrosine phosphorylation of the 41 kDa and 43 kDa cytosol proteins using PT-pretreated (inactivation of PT-sensitive GTP-binding protein) or phorbol 12-myristate 13-acetate (PMA)-pretreated (depletion of PKC) mouse fibroblasts. The effects of the inactivation of PT-sensitive GTP-binding protein and the depletion of PKC on mitogen-stimulated tyrosine phosphorylation of the proteins were similar and varied significantly and systematically in response to growth factors. The important finding was that such inhibitory effects of PT-sensitive GTP-binding protein inactivation and PKC depletion on protein tyrosine phosphorylation induced by each mitogen always correlated well with their inhibitory effects on each mitogen-stimulated DNA synthesis. Although the extent of platelet-derived-growth-factor-induced phosphorylation of the proteins was decreased to approx. 50% in PT- and PMA-pretreated cells compared with native cells, protein phosphorylation itself was not affected and occurred at identical sites on each protein in native, PT- and PMA-pretreated cells. These results suggest that: (1) 41 kDa and 43 kDa proteins are located downstream of PT-sensitive GTP-binding protein and PKC in the mitogenic signalling pathways of growth factors, (2) protein phosphorylation occurs via a cascade of events which includes the activation of the receptor tyrosine kinases, PKC and other unidentified kinase(s) which directly participate(s) in the phosphorylation of the 41 kDa and 43 kDa proteins, and (3) their phosphorylation may play an important role in integrating multiple mitogenic signalling pathways.
 ...
PMID:Mitogen-induced tyrosine phosphorylation of 41 kDa and 43 kDa proteins. Potential role in integrating multiple mitogenic signalling pathways. 144 50

The novel calcium indicator fura red and the oxidative burst indicator dihydrorhodamine (both excited at 488 nm) were used in combination with multiparameter flow cytometry to allow simultaneous kinetic measurements of calcium fluxes and oxidative bursts in monocytes and granulocytes. Using this method it was possible to obtain direct evidence for the following cell type- and stimulus-specific differences in signal transduction pathways: 1) n-formyl-methionyl-leucyl-phenylalanine (FMLP)/cytochalasin B-induced oxidative burst is several-fold higher in granulocytes than in monocytes although the calcium fluxes have similar amplitudes in the two cell types; 2) stimulus-induced calcium fluxes in granulocytes are mainly due to release from intracellular stores, whereas monocytes mobilize calcium mainly by influx from the medium; 3) the FMLP/cytochalasin B-induced calcium flux in monocytes is less sensitive to the G-protein inhibitor pertussis toxin than the flux in granulocytes; 4) in contrast to FMLP/cytochalasin B, the protein kinase C activator phorbol myristate acetate (PMA) induces an oxidative burst that is not preceded by a cytoplasmic calcium flux; 5) the PMA-induced oxidative burst can be triggered in monocytes and granulocytes that are depleted of intracellular calcium ions, whereas that induced by FMLP/cytochalasin B can not; 6) the G-protein inhibitor pertussis toxin blocks an early event in the signal transduction pathway of FMLP/cytochalasin B, as shown by inhibition of both calcium fluxes and oxidative burst; and 7) 100 nM of the protein kinase inhibitor staurosporine blocks the FMLP/cytochalasin B-induced respiratory burst by interfering with a step downstream to cytoplasmic calcium fluxes, whereas only 10-20 nM is necessary to block PMA-induced oxidative burst.
 ...
PMID:Signal transduction in monocytes and granulocytes measured by multiparameter flow cytometry. 145

We studied the regulation of arachidonic acid (AA) release by guanosine 5'-O-(3-thiotriphosphate (GTP gamma S) and Ca2+ in electropermeabilized HL60 granulocytes. Stimulation of AA release by GTP gamma S and Ca2+ was mediated by phospholipase A2 (PLA2) and required the presence of MgATP (EC50: 100-250 microM). The nucleotide effects were Ca(2+)-dependent (maximal effects detected at 1 microM free cation). UTP and ATP gamma S, which stimulate AA release in intact HL60 granulocytes with potencies and efficacies similar to those of ATP, were ineffective in supporting the effects of GTP gamma S in electropermeabilized cells. Pretreatment with pertussis toxin affected stimulation of AA release by ATP in intact cell, without altering the nucleotide effects in permeabilized cells. We observed the protein kinase C-dependent phosphorylation of PLA2 in permeabilized HL60 granulocytes, together with a correlation between the effects of phorbol esters and staurosporine on this reaction and on AA release. ATP-independent activation of PLA2 by GTP gamma S and/or Ca2+ was measured in subcellular fractions prepared from HL60 granulocytes. These data appear consistent with a model in which PLA2 activity in resting HL60 granulocytes is subjected to an inhibitory constraint that prevents its activation by Ca2+ and G-proteins. Removal of this constraint, either by the protein kinase C-dependent phosphorylation of the enzyme in vivo or physical disruption of the regulatory assembly (e.g. by N2 cavitation), allows its activation by Ca2+ and G-proteins.
 ...
PMID:Phosphorylation-dependent regulation of phospholipase A2 by G-proteins and Ca2+ in HL60 granulocytes. 146 9

Catecholamines have been shown to activate hypothalamic corticotropin-releasing factor-41 (CRF) synthesis and release. In order to study the mechanisms involved, fetal hypothalamic cells were cultured and CRF release was measured by radioimmunoassay. Norepinephrine (NE) induced CRF release in a dose-dependent manner. Further studies were performed with a protein kinase C inhibitor, H-7(1-(5-isoquinolinesulfonyl)-2-methylpiperazine) and a protein kinase A inhibitor, IP-20. NE-stimulated CRF release was reduced by H-7 (5 and 50 microM) in a dose-dependent fashion, while 5 microM IP-20 resulted in a small but significant inhibition. Pretreatment of the cells for 15 h with 20 and 200 nM 12-O-tetradecanoylphorbol-13-acetate, which down-regulates protein kinase C activity, blocked the release of CRF in response to NE (1 microM), further supporting protein kinase C as a mediator for NE-activated CRF release. Pretreatment with 50 and 500 ng/ml pertussis toxin (15 h) resulted in a dose-dependent inhibition of NE-activated CRF release. Both dexamethasone and aldosterone at the concentrations of 1 microM reduced NE-induced CRF release. These results suggest that CRF can be released from hypothalamic neurons in response to NE through both protein kinase C- and protein kinase A-dependent mechanisms, and that pertussis toxin-sensitive G-proteins are also involved in this response. Furthermore, glucocorticoids and mineralocorticoids can reduce NE-activated CRF release from cultured hypothalamic cells.
 ...
PMID:Mechanisms of norepinephrine mediated corticotropin-releasing factor-41 release from cultured fetal hypothalamic cells. 148 3

This review outlines evidence that IL-1, IL-2, and TNFs modulate neutrophil functions. These cytokines affect some or all of the following functions of the neutrophil: adherence, cell migration, respiratory burst, lysosomal enzyme release, and cell surface receptor expression. TNFs, especially TNF alpha, remains one of the most highly studied cytokine with respect to regulation of neutrophil function. TNFs are a direct stimuli for the neutrophil respiratory burst and weak stimuli of lysosomal enzyme release. The cytokines enhance cell adhesion and inhibit neutrophil migration. The TNFs augment the oxidative burst and lysosomal enzyme release response to a wide range of soluble and particulate cell stimuli. These changes in the cell seem to be closely correlated with the increased fungicidal, bactericidal, tumoricidal, and protozoacidal activity of the TNF-primed neutrophils. In contrast to TNFs, IL-1 and IL-2 inhibit neutrophil adherence, and this provides evidence that the cytokine family represents a regulatory system. Another form of regulation of TNF alpha and IL-1 neutrophil-activating activity is by the release of inhibitors to these cytokines (58). We have evidence which shows that the soluble TNF alpha inhibitor (a cleaved product of the TNF alpha receptor) (59) binds and inhibits TNF from activating and priming neutrophils (60). Priming of neutrophils by TNFs involves surface receptor binding but is independent of protein kinase C system, pertussis toxin-sensitive guanine nucleotide regulatory protein, and direct burst of respiratory activity. The translocation of cell surface receptors and constituents of the NADPH oxidase from stored vesicles may be the major mechanism of TNF-induced cell priming.
 ...
PMID:Activation of neutrophils by interleukins-1 and -2 and tumor necrosis factors. 150 43

Macrophage colony-stimulating factor (M-CSF) is required for the proliferation, differentiation, and activation of monocytes. High-affinity receptors for M-CSF are encoded by the c-fms proto-oncogene. In the present study, we show that c-fms transcripts are detectable in human THP-1 myeloid leukemia cells. Furthermore, radiolabeled 125I-M-CSF is rapidly internalized into THP-1 cells and then degraded intracellularly. The results also show that treatment of THP-1 cells with M-CSF is associated with the activation of protein kinase C (PKC) and the induction of tumor necrosis factor (TNF) gene expression. TNF transcript levels were low to undetectable in uninduced THP-1 cells, reached maximal levels by 1 hour of exposure to M-CSF, and returned to those of control cells by 24 hours. Transcriptional run-on analysis showed that a low level of TNF transcription is detectable in untreated THP-1 cells, and M-CSF treatment increased the rate of TNF transcription. Pretreatment of THP-1 cells with pertussis toxin inhibited the increase in PKC activity but not the induction of TNF transcripts by M-CSF. Moreover, exposure of THP-1 cells to inhibitors of protein kinase activity blocked the increase in TNF messenger RNA. These findings suggest that at least two M-CSF-mediated signaling pathways exist in THP-1 cells and that the induction of TNF may be regulated by a protein kinase-dependent mechanism distinct from PKC.
 ...
PMID:Functional expression of the macrophage colony-stimulating factor receptor in human THP-1 monocytic leukemia cells. 153 7

A number of lines of evidence indicate that the Ca2+ and cyclic AMP signalling systems interact in NCB-20 cells. However, to date, the regulation of [Ca2+]i homeostasis has not been studied in this cell line. The present study aimed to clarify our understanding of [Ca2+]i homeostasis in these cells and to evaluate tools that manipulate [Ca2+]i, independently of protein kinase C effects. Bradykinin, by a B2-receptor, elevated [Ca2+]i by a pertussis-toxin-insensitive mechanism. The BK-stimulated [Ca2+]i rise originated from intracellular sources, without a contribution from Ca2+ entry mechanisms. The effect of BK was precluded by pretreatment with thapsigargin and ionomycin--compounds that elevated [Ca2+]i independent of phospholipase C activation. Both compounds, however, exerted effects in addition to stimulating release of Ca2+ from BK-sensitive stores; the BK-sensitive Ca2+ pool was a subset of the thapsigargin-sensitive pool; ionomycin strongly stimulates Ca2+ entry. Activation of protein kinases A and C attenuated the duration of the BK-induced rise in [Ca2+]i, without affecting the peak [Ca2+]i, suggesting interference with the BK response at a step downstream of the activation of phospholipase C. Application of these approaches should enhance the delineation of the consequences of Ca2+ mobilization on cyclic AMP accumulation.
 ...
PMID:Manipulation of intracellular calcium in NCB-20 cells. 153 72

Recently, we reported that in mouse mastocytoma P-815 cells the cytosol contains some factor(s) which promotes the release of GTP-activated Gi2 alpha from the membrane, and that thrombin induces the translocation of Gi2 alpha from the membrane to the cytosol (Takahashi, S., Negishi, M. and Ichikawa, A. (1991) J. Biol. Chem. 266, 5367-5370). Here we investigated the mechanism underlying the thrombin-induced translocation of Gi2 alpha in mastocytoma cells. Thrombin induced a rapid and transient increase in the intracellular Ca2+ concentration ([Ca2+]i) within 1 min, attenuated pertussis toxin-catalyzed ADP-ribosylation of Gi2 in the membrane, and caused the subsequent translocation of Gi2 alpha. Thrombin induced the translocation of protein kinase C from the cytosol to the membrane, and a protein kinase C inhibitor, staurosporine, completely inhibited the thrombin-induced translocation of Gi2 alpha. When cells were treated with thrombin, the ability of the cytosol to release Gi2 alpha from the membrane in the presence of GTP gamma S markedly increased. This stimulatory effect of thrombin on the ability of the cytosol was mimicked by 12-O-tetradecanoylphorbol 13-acetate (TPA), but not by the Ca2+ ionophore, ionomycin. The thrombin- and TPA-induced potentiation of the ability of the cytosol to release Gi2 alpha was completely abolished by staurosporine. Furthermore, phosphorylation of the cytosol by protein kinase C markedly potentiated the ability of the cytosol to release Gi2 alpha. These results together demonstrate that the thrombin-induced translocation of Gi2 alpha is due to enhancement of the ability of the cytosol to release Gi2 alpha via activation of protein kinase C.
 ...
PMID:Involvement of protein kinase C in thrombin-induced translocation of Gi2 alpha from the membrane to the cytosol in mouse mastocytoma P-815 cells. 154 55


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