Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.1 (protein kinase)
 81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have examined the presence of protein kinase C in oocytes of Chaetopterus pergamentaceus and its role in the initiation of germinal vesicle breakdown (GVBD). First, we demonstrated that the oocytes contain a phospholipid- and calcium-dependent protein kinase, protein kinase C (PKC). Since PKC is the primary intracellular receptor for phorbol esters, we tested the ability of phorbol 12,13-dibutyrate (PDBu) to induce GVBD and compared several critical events and processes involved in GVBD induced by PDBu to those induced normally (by seawater). Seawater and 100-200 nM PDBu induced chromosome condensation, spindle formation, and spindle migration over a similar time course. Both treatments induced similar alterations in the SDS-PAGE pattern of newly synthesized proteins. The synthesis of polypeptides of approximately 46 and 54 kDa increased specifically. Both treatments increased oocyte protein phosphorylation, especially of proteins of 22, 32, 46, 55, 64, and 84 kDa. Both treatments resulted in the activation of an M-phase-specific histone H1 kinase activity, which demonstrates the appearance of maturation-promoting factor. Staurosporine, a potent protein kinase C inhibitor, blocked GVBD and the activation of M-phase-specific H1 kinase, whereas HA1004, which preferentially antagonizes protein kinase A, had no effect. The results of this study demonstrate that protein kinase C can activate a wide spectrum of essential biochemical and morphological processes involved in GVBD. Further, these studies suggest that protein kinase C elicits GVBD by activating maturation-promoting factor and support the hypothesis that protein kinase C plays an essential role in oocyte maturation in this species.
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PMID:Regulation of M-phase progression in Chaetopterus oocytes by protein kinase C. 130 10

Transcriptional activation of the murine Cyp1a-1 (cytochrome P(1)450) gene by inducers such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) (dioxin) requires the aromatic hydrocarbon (Ah) receptor and the interaction of an inducer-receptor complex with one or more of the Ah-responsive elements (AhREs) located about 1 kb upstream from the transcriptional initiation site. We find that treatment of mouse hepatoma Hepa-1 cells with 2-aminopurine, an inhibitor of protein kinase activity, inhibits CYP1A1 mRNA induction by TCDD as well as the concomitant increase in CYP1A1 enzyme activity. Formation of DNA-protein complexes between the Ah receptor and its AhRE target is also inhibited by 2-aminopurine, as determined by gel mobility shift assays. Phosphorylation is required for the formation of Ah receptor-specific complexes, since in vitro dephosphorylation of nuclear extracts from TCDD-treated Hepa-1 cells abolishes the capacity of the Ah receptor to form specific complexes with its cognate AhRE sequences. To determine whether any one of several known protein kinases was involved in the transcriptional regulation of the Cyp1a-1 gene, we treated Hepa-1 cells with nine other protein kinase inhibitors prior to induction with TCDD; nuclear extracts from these cells were analyzed for their capacity to form specific DNA-protein complexes. Only extracts from cells treated with staurosporine, a protein kinase C inhibitor, were unable to form these complexes. In addition, staurosporine completely inhibited CYP1A1 mRNA induction by TCDD. Depletion of protein kinase C by prolonged treatment with phorbol ester led to the complete suppression of CYP1A1 mRNA induction by TCDD. We conclude that (i) phosphorylation is necessary for the formation of a transcriptional complex and for transcriptional activation of the Cyp1a-1 gene; (ii) the phosphorylation site(s) exists on at least one of the proteins constituting the transcriptional complex, possibly the Ah receptor itself; and (iii) the enzyme responsible for the phosphorylation is likely to be protein kinase C.
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PMID:Dioxin-dependent activation of murine Cyp1a-1 gene transcription requires protein kinase C-dependent phosphorylation. 131 72

In vitro luteinization of bovine granulosa (LGC) and theca (LTC) cells was achieved by culturing cells with forskolin (10 microM) and insulin (2 micrograms/ml) for 9 days. This treatment induced the presence of cytochrome P450scc and adrenodoxin in both cell types, but to substantially higher levels in LGC than in LTC. Forskolin dose-dependently stimulated the secretion of progesterone and cAMP after 3 h of incubation in both cell types although LGC were less sensitive to this stimulation than were LTC. Only LTC were responsive to LH, in accordance with their higher LH/hCG binding capacity. Both prostaglandin F2 alpha (PGF2 alpha) and phorbol 12-myristate 13-acetate (TPA) increased progesterone production during 3 h incubation of LGC and LTC, and treatment with staurosporine (a protein kinase C inhibitor) reversed this effect. Neither TPA nor PGF2 alpha alone affected cAMP levels but each acted synergistically with forskolin to increase cAMP accumulation. These results indicate that 1) elevated progesterone output from LGC is related to steroidogenic enzyme level; 2) bovine LH (up to 100 ng/ml) does not provoke a response in LGC due to their low LH/hCG binding capacity; 3) cAMP-protein kinase A and protein kinase C pathways are both involved in progesterone production by LGC and LTC, possibly by enhancing cholesterol transport.
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PMID:Steroidogenic enzyme content and progesterone induction by cyclic adenosine 3',5'-monophosphate-generating agents and prostaglandin F2 alpha in bovine theca and granulosa cells luteinized in vitro. 131 23

Arachidonic acid metabolism in resident rat alveolar macrophages and in those activated with complete Freund's adjuvant (CFA) was studied. Adult Sprague-Dawley rats were injected with 0.05 ml CFA, and macrophages were harvested 10 days later. Macrophages were labeled overnight with carbon 14-labeled arachidonic acid, washed, and then stimulated with calcium ionophore A23187 (IoA), phorbol myristate acetate (PMA), or zymosan for 30 minutes. Prostaglandins, thromboxane, and leukotrienes were extracted from the medium and analyzed by radioimmunoassay or radio high-pressure liquid chromatography. Cell lipids were analyzed by radio thin-layer chromatography. Medium and cell beta-glucuronidase activity and protein kinase C activity of the membrane fraction were also assayed. We found (1) lower leukotriene B4 (LTB4) production in stimulated resident macrophages when compared with resident macrophages after IoA stimulation--the suppressed LTB4 production was reversed by PMA; (2) unchanged or higher LTB4 production in activated macrophages when compared with resident macrophages after zymosan stimulation; (3) inhibition of zymosan-stimulated LTB4 production by staurosporine, a protein kinase C inhibitor, in both groups; and (4) lower diacylglycerol (DAG) production in activated macrophages when compared with resident macrophages after IoA stimulation, but not after zymosan stimulation. These results suggest that the reduced response of activated macrophages to IoA is due to decreased production of an endogenous protein kinase C activator. This hypothesis was further supported by the observation that protein kinase C activation in response to IoA was lower in activated macrophages than in resident macrophages. In contrast, zymosan stimulation resulted in higher protein kinase C activation in activated macrophages when compared with resident cells. We hypothesize that protein kinase activation is necessary for leukotriene production and that the preserved ability of zymosan to activate PKC via DAG accounts for the high leukotriene production in zymosan-activated macrophages. We also found that stimulated thromboxane production was higher in activated than resident cells, regardless of the stimulus, and that thromboxane production was not affected by staurosporine. Thus alterations of eicosanoid metabolism in immunologically activated macrophages depend on the stimulus used and the type of eicosanoid examined. Furthermore, leukotriene biosynthesis in rat alveolar macrophages may be regulated by protein kinase C.
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PMID:Production of leukotrienes and thromboxane by resident and activated rat alveolar macrophages: a possible role of protein kinase C. 132 31

The mechanism of immunosuppressant activity of phosphatidylserine has been studied in peripheral blood mononuclear cells depleted or not of monocytes. After the addition of phosphatidylserine, mass determinations and uptake of labeled compound demonstrate its transfer into the cells. Phosphatidylserine incorporation causes a 2.5-fold increase of membrane-bound protein kinase C activity. The activation of translocated enzyme is indicated by the inhibition of phosphoinositide hydrolysis, and early feedback effect induced by activated protein kinase C. This action of phosphatidylserine is reproduced by tetradecanoylphorbolacetate and is prevented by the protein kinase C inhibitor, staurosporine. Consistently, phosphatidylserine (8 nmol/10(6) cells) decreases by 46% the production of inositol phosphates in cells responding to phytohemagglutinin. The decrease of phosphoinositide signal pathway as well as the inhibition of mitogen-induced DNA synthesis are produced at the same phosphatidylserine concentration and are equally manifest in total mononuclear cells or in preparations depleted of monocytes. However, only in the presence of monocytes does tetradecanoylphorbolacetate enhance the action of phospholipid, decreasing its IC50 from 13-15 microM to 7 microM. Thus, the data suggest that a reaction driven by protein kinase-C and a factor released by activated monocytes are involved in the phosphatidylserine-induced inhibition of lymphocyte DNA synthesis.
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PMID:Role of protein kinase C in the phosphatidylserine-induced inhibition of DNA synthesis in blood mononuclear cells. 133 10

The role of protein kinase C in radiation-induced death of thymocytes was studied. For this purpose murine thymocytes were irradiated and incubated for 6 h at 37 degrees C and afterwards the fraction of fragmented DNA was measured. Results indicate that radiation-induced DNA fragmentation can be prevented by adding the protein kinase C inhibitor H-7 or staurosporine to the thymocytes during incubation time. Incubation of irradiated cells with HA-1004, an inhibitor of cAMP-dependent protein kinase, with a minor effect on protein kinase C did not affect the DNA fragmentation induced by irradiation. Incubation of cells with phorboldibutyrate gave a dose-dependent induction of DNA fragmentation. This effect can be inhibited by staurosporine. These results suggest that radiation-induced DNA fragmentation is an active cellular process in which protein kinase C plays an important role.
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PMID:Role of protein kinase-C in thymocyte apoptosis induced by irradiation. 134 30

Lymphocyte adhesion to target cells is mediated, in part, by the interaction of lymphocyte function-associated Ag-1 (LFA-1) with intercellular adhesion molecule-1 (ICAM-1). Cells of the B cell line, JY, express both coreceptors and have been used as a model for intercellular adhesion mediated by these molecules. Elevation of the intracellular cAMP concentration ([cAMP]i), by any of several reagents, for periods as brief as 30 min, led to enhanced intercellular adhesion in a concentration dependent manner 5 to 8 h later. Two protein kinase A inhibitors, KT5720 and H-89, but not the protein kinase C inhibitor calphostin C, blocked the effects of elevated [cAMP]i. These data suggest a role for protein kinase A in this response. The adhesion augmented by increased [cAMP]i was due to LFA-1/ICAM-1 interactions between cells because it was blocked by either anti-LFA-1 or anti-ICAM-1 mAb. Elevated [cAMP]i induced cell surface patching of LFA-1, but not ICAM-1, and this redistribution preceded intercellular adhesion. Finally, redistribution of LFA-1 was not mediated by the cytoskeleton. These results suggest a model in which transient activation of protein kinase A results in increased local concentration of LFA-1 at the cell surface and in augmented long term adhesion mediated by this integrin.
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PMID:Lymphocyte adhesion mediated by lymphocyte function-associated antigen-1. I. Long term augmentation by transient increases in intracellular cAMP. 135 27

The light-activated protein kinase C inhibitor, calphostin C, is shown to inhibit the ability of IL-3-dependent 32D cells to reduce the tetrazolium salt, MTT. To determine whether this inhibition was mediated through mitochondria which have been implicated in MTT reduction, isolated mitochondria were treated with calphostin C in the presence of various substrates for mitochondrial electron transport and EDTA (to exclude PKC involvement). Calphostin C extensively inhibited succinate-dependent MTT reduction (IC50 = 110nM) but had little effect on either NADH- or NADPH-dependent MTT reduction. An alternative protein kinase C inhibitor, H7, did not affect succinate-dependent mitochondrial MTT reduction, and the protein kinase A inhibitor, KT5720, had little effect on either cellular or mitochondrial MTT reduction. These results show that in addition to its role as a PKC inhibitor, calphostin C is also a potent inhibitor of succinate-dependent mitochondrial electron transport.
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PMID:The protein kinase C inhibitor, calphostin C, inhibits succinate-dependent mitochondrial reduction of MTT by a mechanism that does not involve protein kinase C. 137 66

Treatment of bovine chromaffin cells with nicotinic agonists, phorbol esters, and growth factors increases protein kinase activity toward microtubule-associated protein-2 and myelin basic protein (MBP) in vitro. To characterize the kinases that are activated by these agents, we separated chromaffin cell proteins by electrophoresis in sodium dodecyl sulfate-polyacrylamide gels into which MBP had been incorporated, allowed the proteins to renature, and then assayed MBP kinase activity by incubating the gels with [gamma-32P]ATP. Chromaffin cells contain a family of kinases that phosphorylate MBP in vitro. Two of these kinases, of M(r) 46,000 and 42,000 (PK46 and PK42), were activated by treatment of the cells with dimethylphenylpiperazinium (DMPP), phorbol 12,13-dibutyrate (PDBu), or insulin-like growth factor I (IGF-I). Activation of PK46 and PK42 by DMPP was dependent on extracellular Ca2+, whereas the effects of PDBu and IGF-I were Ca2+ independent. Down-regulation of protein kinase C by incubation of the cells with PDBu abolished the activation of PK46 and PK42 by DMPP, PDBu, and IGF-I. Staurosporine, a protein kinase C inhibitor, prevented the activation of PK46 and PK42 by DMPP and PDBu but did not block the activation of these kinases by IGF-I. Immunoblotting experiments with antiphosphotyrosine (anti-PTyr) antibodies demonstrated that agents that increased the kinase activities of PK46 and PK42 also increased the apparent PTyr content of M(r) 46,000 and 42,000 proteins. PK46 and PK42 comigrated with proteins that reacted with antibodies against extracellular signal-regulated kinases (ERKs). Thus, PK46 and PK42 appear to be the bovine homologues of ERK1 and ERK2.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Nicotinic agonists, phorbol esters, and growth factors activate two extracellular signal-regulated kinases, ERK1 and ERK2, in bovine chromaffin cells. 143 97

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.
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PMID:Mechanisms of norepinephrine mediated corticotropin-releasing factor-41 release from cultured fetal hypothalamic cells. 148 3


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