Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:2.7.11.1 (protein kinase)
81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

It has been proposed that protein kinase C mediates cellular responses evoked by external stimuli, leading to alterations in internal free calcium concentrations. We have shown previously that histamine-secreting rat basophilic leukaemia cells (RBL-2H3), which degranulate on aggregation of the receptors for immunoglobulin IgE, contain a Ca2+- and phospholipid-dependent protein kinase (kinase C). The partially purified enzyme is activated directly by the tumour-promoting phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA). In intact RBL cells, TPA potentiates histamine release induced by the Ca2+-ionophore A23187 (similar to the synergy reported for platelets, neutrophils and rat peritoneal mast cells). Although TPA at concentrations below 15 nM synergizes with the antigen, higher TPA concentrations inhibit secretion. This selective inhibition suggested that kinase C is involved in both the activation and termination of the secretory process. To examine this possibility, we have determined the effect of TPA on changes in free cytosolic Ca2+ concentration during antigen-induced release. We report here that TPA completely blocks the increase in Ca2+ concentration induced by antigen. Our results strongly suggest that protein kinase C is involved in the regulation of receptor-dependent Ca2+ signalling.
...
PMID:Protein kinase C regulation of the receptor-coupled calcium signal in histamine-secreting rat basophilic leukaemia cells. 257 17

RBL cells provide a useful model of the IgE and antigen-dependent stimulus-secretion coupling of mast cells and basophils. We have measured cellular deformability to investigate the participation of cytoskeletal mechanical changes. Cross-linking cell-surface IgE-receptor complexes with multivalent ligands not only triggered secretion but also caused the cells to stiffen, i.e., to become more resistant to deformation. This mechanical response required receptor cross-linking, had a time course similar to that of secretion, and was reversed by DNP-L-lysine, a competitive inhibitor of antigen binding. Hence the same stimulus seems to elicit both stiffening and secretion. Cytochalasin D, which inhibits actin filament assembly, prevented or reversed stiffening, thereby implicating the cytoskeleton in the mechanical response. Increasing intracellular calcium ion concentration with the ionophore A23187 stiffened cells and stimulated secretion. Activation of protein kinase C with a phorbol ester also stiffened cells and enhanced both the stiffening and secretion caused by the ionophore. Yet cytochalasin D enhances secretion whereas activation of protein kinase c alone is insufficient for secretion. Therefore stiffening is neither necessary nor sufficient for secretion. These results characterize a cytoskeletal mechanical response triggered by the same receptor-dependent stimulus that elicits secretion and by second messengers that are thought to mediate between the receptor signal and secretion. The function of the mechanical response, however, remains to be determined.
...
PMID:Rat basophilic leukemia cells stiffen when they secrete. 296 69

Evidence is presented that RBL-1 cells, which are similar to normal rat mast cells in morphology and contain IgE receptors and histamine, contain a calcium-activated, phospholipid, diacylglycerol-dependent protein kinase. This enzyme is very similar in its activation requirements to the calcium-dependent enzyme termed protein kinase C in other tissues. The enzyme is activated by Ca2+. Diolein, but not other di, mono or triglycerides, substantially increases the enzyme activity. Among various phospholipids, phosphatidylserine is the most reactive activator; phosphatidylinositol, phosphatidic acid and phosphatidylethanolamine are less effective; and phosphatidylcholine is practically inactive. The enzyme is inhibited by chlorpromazine and local anesthetics such as dibucaine, tetracaine and procaine.
...
PMID:[Studies of phosphorylation in rat mast cells (third report)--isolation of calcium-activated, phospholipid, diacylglycerol-dependent protein kinase from rat basophilic leukemia cells (RBL-1 cells)]. 299 15

Cross-linking of receptor bound IgE antibodies by multivalent antigen (DNP8-BSA) on PB-3c cells leads to an increase of cytosolic calcium ((Ca2+)i). Active tumor promoting phorbol esters and teleocidin which specifically activate the phospholipid Ca2+-sensitive protein kinase (PKC), inhibited the antigen-mediated rise in (Ca2+)i and induced a time and dose-dependent translocation of cytosolic PKC to membranes of the PB-3c cells as determined by enzyme activity or immunoblotting using a polyclonal anti-PKC antibody. This TPA concentration did not affect the subcellular distribution of PKC, although 1 nM of 12-O-tetradecanoylphorbol-13-acetate (TPA) inhibited to 50% the antigen-mediated increase in (Ca2+)i. The concentration of TPA required to induce a half-maximal subcellular redistribution of immunodetectable PKC activity was an order of magnitude greater than the half-maximal dose required to inhibit the antigen-mediated increase in (Ca2+)i. These data demonstrate that the TPA-dependent activation of PKC is not directly coupled to its translocation to membranes.
...
PMID:Translocation of protein kinase C is not required to inhibit the antigen-induced increase of cytosolic calcium in a mast cell line. 310 18

The murine mast cell line PB-3c is dependent on interleukin 3 (IL-3) with respect to survival and proliferation. These cells also require IL-3 to display antigen-mediated serotonin release, which is coupled to a transient increase of cytosolic free calcium ([Ca2+]i). The antigen-mediated exocytosis is inhibited by phorbol 12-tetradecanoate 13-acetate (PTA), an activator of phospholipid/Ca2+-sensitive protein kinase. In contrast, the malignant mast cell variant PB-1 is IL-3 independent with respect to proliferation but is unable to undergo antigen-mediated exocytosis. Yet this cell line exhibits basal levels of [Ca2+]i, serotonin content, and numbers of IgE receptors comparable to those of PB-3c cells. Subcellular distribution studies revealed that the specific activity of cytosolic protein kinase C of PB-1 cells was only 40% of that found in PB-3c cells. Furthermore, the PB-1 cells showed a significantly higher specific activity of membrane-bound protein kinase C than PB-3c cells. Scatchard plot analysis of [3H]-phorbol 12,13-dibutyrate binding to intact PB-1 cells demonstrated the presence of 20% high-affinity (Kd = 6 nM) and 80% low-affinity (Kd = 60 nM) phorbol ester receptors, whereas PB-3c cells displayed only the low-affinity phorbol ester binding. Immunological characterization of protein kinase C from both cell lines revealed the presence of a normal 77-kDa protein kinase C holoenzyme in both cell lines. In addition, a 72-kDa protein kinase C-related protein band was found mainly in the membrane fraction of the PB-1 variant. It is suggested that this altered and membrane-bound form of protein kinase C may be involved in the blockage of the antigen-mediated exocytosis of PB-1 cells.
...
PMID:Altered protein kinase C in a mast cell variant defective in exocytosis. 349 90

Evidence is presented that rat serosal mast cells and cells of the rat basophilic leukemia line, RBL-1, each contain a calcium-activated, phospholipid-dependent protein kinase. The enzymes are very similar in their activation requirements to the calcium-dependent enzymes termed protein kinase Cs in brain. The enzyme is selectively stimulated by diolein and phosphatidylserine and is inhibited by several local anesthetics. The Ka for Ca2+ is 1.0 X 10(-3) M and 1.5 X 10(-4) M in mast cells and RBL-1 cells, respectively. The enzyme in mast cells is rapidly activated and apparently changed in its intracellular distribution when intact mast cells are stimulated with 48/80, A-23187, and anti-IgE and 12-O-tetradecanoyl-13-acetate in combination.
...
PMID:Characterization of calcium-activated, phospholipid-dependent protein kinase from rat serosal mast cells and RBL-1 cells. 380 10

Cells of the T cell hybridoma 23A4 produce IgE-binding factors lacking N-linked oligosaccharides (unglycosylated form) when they are incubated with IgE alone. In the presence of glycosylation-enhancing factor (GEF) or bradykinin, however, the same cells produce IgE-binding factors with N-linked oligosaccharides (glycosylated form). Switching the cells from the formation of unglycosylated IgE-binding factors to the formation of glycosylated factors was accompanied by the release of both glycosylation-inhibiting factor (GIF) in its phosphorylated form, i.e., phosphorylated lipomodulin, and arachidonate from the cells. Analysis of the biochemical processes for the release of GIF from 23A4 cells showed that affinity-purified GEF or bradykinin induced transient phospholipid methylation and diacylglycerol (DAG) formation, and enhanced 45Ca uptake into the cells. Inhibitors of methyltransferases, i.e., 3-deaza-adenosine plus L-homocysteine thiolactone, inhibited not only phospholipid methylation but also DAG formation and GIF release. Exogenously added 1-oleoyl-2-acetyl glycerol, i.e., a DAG that is permeable to the plasma membrane, induced the release of GIF from the cells. It was also found that 12-O-tetradecanoyl-phorbol 13-acetate (TPA) switched 23A4 cells and normal lymphocytes to the selective formation of N-glycosylated IgE-binding factor, and induced the release of GIF from the cells. 32PO4-labeled lipomodulin was detected in the extract of 23A4 cells 3 to 5 min after the addition of GEF, bradykinin, or TPA. These results indicate that GEF and bradykinin induced the activation of methyltransferases and phospholipase C for the formation of DAG, which in turn activated Ca2+-activated, phospholipid-dependent protein kinase (protein kinase C) for the phosphorylation of lipomodulin. Because lipomodulin loses phospholipase inhibitory activity after phosphorylation, increased phospholipase A2 activity would be expressed by this process.
...
PMID:Modulation of the biologic activities of IgE-binding factors. VII. Biochemical mechanisms by which glycosylation-enhancing factor activates phospholipase in lymphocytes. 387 9

This review details the biochemical events that follow IgE dimerization by antigen and cross-linking of receptors and are linked with the early rise in cyclic AMP. That the monophasic rise in cyclic AMP at 15 s is essential to the degranulation process is evident by pharmacological manipulation of adenylate cyclase, using specific activators and inhibitors to achieve potentiation and inhibition of immunologic release, respectively. Although only a small percentage of membrane adenylate cyclase is transmembrane linked to IgE-Fc perturbation, its product, cyclic AMP, is elevated during activation and is responsible for the activation of two protein kinase isoenzymes at 30-60 s. This sequence appears to be essential for secretion to occur, as evidenced by dose-related inhibition of both beta-hexosaminidase release and protein kinase activation by adenylate cyclase inhibitors. Competitive activation of cyclic AMP-dependent protein kinase activity by a phosphodiesterase inhibitor leads to inhibition of mediator release by diverting an essential enzyme or recruiting an inhibitory sequence. The precise functional role of the mast cell cyclic AMP-dependent protein kinases has not yet been identified, but there is much evidence in other cell types that protein phosphorylation is an essential accompaniment to cellular regulation. Although other apparently essential biochemical steps are noted, such as uncovering a serine esterase, methylation of membrane phospholipid, and increased Ca2+ influx, only a portion of the activation-secretion response is presented here as a sequence, namely, the IgE-Fc receptor-initiated, transmembrane-coupled activation of adenylate cyclase and the subsequent cytoplasmic cyclic AMP-dependent activation of types I and II protein kinases.
...
PMID:Enzymatic regulation of mast cell activation and secretion by adenylate cyclase and cyclic AMP-dependent protein kinases. 617 64

The initial monophasic rise in cyclic AMP beginning 5-15 sec after bridging of rat mast cell IgE-Fc receptors precedes the secretion of granule constituents, thereby implying a causal relationship. Direct evidence for a relationship between IgE-dependent transmembrane activation of adenylate cyclase and granule secretion was provided by the capacity of purine-modified (R site active) and ribose-modified (P site active) adenosine analogs, respectively, to augment and suppress mediator release while simultaneously increasing and decreasing the activity of adenylate cyclase. R site stimulation alone does not cause granule secretion but augments the rate and magnitude of IgE-Fc receptor-induced secretion, reflecting the coupled relationship of such receptors. Inhibition of adenylate cyclase at the P site attenuates the rise in cellular cyclic AMP and suppresses IgE-dependent mediator release in a parallel and superimposable dose-response fashion. Further, the relationship between the attenuation in the rise in cyclic AMP and the diminution in immunologic mediator release is linear with the regression line passing through the origin, indicating a direct relationship between the IgE-dependent activation of adenylate cyclase and preformed mediator release. Although not the only events in coupled mast cell activation--secretion, there is a sequential relationship among perturbation of IgE-Fc receptors, transmembrane activation of adenylate cyclase, elevation of cytoplasmic levels of cyclic AMP, activation of cyclic AMP-dependent protein kinase, and secretion of mast cell granules.
...
PMID:Role of adenylate cyclase in immunologic release of mediators from rat mast cells: agonist and antagonist effects of purine- and ribose-modified adenosine analogs. 625 61

Previous studies have shown that perturbation of the mast cell IgE-Fc receptor activates adenylate cyclase so as to raise cellular levels of cyclic AMP and to activate cyclic AMP-dependent protein kinase. Theophylline, an inhibitor of cytoplasmic cyclic nucleotide phosphodiesterase, raises cellular cyclic AMP levels, activates Type I and Type II cytoplasmic cyclic AMP-dependent protein kinase isoenzymes, and inhibits immunologic mediator release in a dose-dependent fashion. Since the EC50 values for each of these effects are similar (8 to 9.5 mM), it seems likely that a relationship exists between the activation of cyclic AMP-dependent protein kinase and the inhibition of mediator release. Such inhibition could be due to either to the uncovering of an inhibitory protein by phosphorylation or to the depletion of cyclic AMP-dependent protein kinase holoenzyme, which is essential for productive IgE-Fc receptor-induced activation-secretion coupling. PGD2, which also raises mast cell cyclic AMP levels in a dose-dependent fashion and interacts synergistically with theophylline in this regard, fails to suppress mediator release alone or to add to the inhibitory effect of theophylline. The finding that PGD2 also fails to activate cyclic AMP-dependent protein kinase suggests that the adenylate cyclase stimulated by this agonist is not linked to the mast cell activation-secretion response.
...
PMID:Effects of prostaglandin D2 and theophylline on rat serosal mast cells: discordance between increased cellular levels of cyclic AMP and activation of cyclic AMP-dependent protein kinase. 626 8


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

---