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 known action of uridine triphosphate (UTP) to contract some types of vascular smooth muscle, and the present finding that it is more potent than adenosine triphosphate in eliciting an increase in cytosolic Ca2+ concentration in aortic smooth muscle, led us to investigate the mode of action of this nucleotide. With this aim, cultured bovine aorta cells were subjected to patch-clamp methodologies under various conditions. Nucleotide-induced variations in cytosolic Ca2+ were monitored by using single channel recordings of the high conductance Ca(2+)-activated K+ (Maxi-K) channel within on-cell patches as a reporter, and whole-cell currents were measured following perforation of the patch. In cells bathed in Na(+)-saline, UTP (> 30 nM) induced an inward current, and both Maxi-K channel activity and unitary current amplitude of the Maxi-K channel transiently increased. Repetitive exposures elicited similar responses when 5 to 10 min wash intervals were allowed between challenges of nucleotide. Oscillations in channel activity, but not oscillation in current amplitude were frequently observed with UTP levels > 0.1 microM. Cells bathed in K+ saline (150 mM) were less sensitive to UTP (approximately 5-fold), and did not show an increase in unitary Maxi-K current amplitude. Since the increase in amplitude occurs due to depolarization of the cell membrane, a change in amplitude was not observed in cells previously depolarized with K+ saline. The enhancement of Maxi-K channel activity in the presence of UTP was not diminished by Ca2+ entry blockers or by removal of extracellular Ca2+. However, in the latter case, repetitive responses progressively declined. These observations, as well as data comparing the action of low concentrations of Ca2+ ionophores (< 5 microM) to that of UTP indicate that both agents elevate cytosolic Ca2+ by mobilization of this ion from intracellular pools. However, the Ca2+ ionophore did not cause membrane depolarization, and thus did not change unitary current amplitude. The effect of UTP on Maxi-K channel activity and current amplitude was blocked by pertussis toxin and by phorbol 12-myristate 13-acetate (PMA), but was not modified by okadaic acid, or by inhibitors of protein kinase C (PKC). Our data support a model in which a pyrimidinergic receptor is coupled to a G protein, and this interaction mediates release of Ca2+ from intracellular pools, presumably via the phosphatidyl inositol pathway. This also results in activation of membrane channels that give rise to an inward current and depolarization. Ultimately, smooth muscle contraction ensues.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Mobilization of intracellular calcium in cultured vascular smooth muscle cells by uridine triphosphate and the calcium ionophore A23187. 827 Dec 67

T2, an extract of Tripterygium wilfordii Hook F, has been reported to be effective in the treatment of a variety of autoimmune diseases, including rheumatoid arthritis. Previous studies have shown that T2 inhibited mitogen- or antigen-induced proliferation of human peripheral blood T cells and B cells, IL-2 production by T cells and Ig production by B cells. In contrast, T2 did not affect monocyte functions, such as IL-1 production and antigen presentation. The current studies sought to localize the immunosuppressive action of T2 more precisely. Results show that T2 prevented [3H]-uridine uptake by mitogen-stimulated T cells and arrested them in the early GI phase of the cell cycle. The inhibitory effects of T2 could be partially overcome by costimulating PHA activated T cells with PMA and completely nullified by costimulation with PMA plus a monoclonal antibody to CD28. Moreover, T2 had no effect on expression of IL-2R or the transferrin receptor (CD71), but inhibited production of a number of cytokines, including IL-2 and IFN-gamma by activated T cells. T2 suppressed IL-2 mRNA levels, but not IL-2R mRNA levels, in activated T cells. T2-mediated inhibition reflected suppression of IL-2 gene transcription as indicated by suppression of the expression of a reporter gene driven by the IL-2 promoter. T2 had little inhibitory effect on either IL-2 gene expression or cell cycle progression when added after initial mitogenic stimulation, indicating that an early step in the cascade of activation events was inhibited. However, initial activation events including protein tyrosine phosphorylation, the generation of diacylglycerol, IP3, and the translocation of protein kinase C were not inhibited by T2. Moreover, T2 did not inhibit the phosphatase activity of calcineurin. These results have localized the effect of T2 to a step in the T cell activation cascade after initial second messenger generation, tyrosine phosphorylation and protein kinase activation, but before IL-2 gene transcription.
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PMID:The Chinese herbal remedy, T2, inhibits mitogen-induced cytokine gene transcription by T cells, but not initial signal transduction. 855 49

This study was designed to determine the effects of concanavalin A (ConA) (a T-cell mitogen) and phorbol myristate acetate (PMA) (an activator of protein kinase C) plus ionomycin (Iono) on glutamine metabolism and proliferation of porcine intestinal intraepithelial lymphocytes (IEL). IEL were prepared from jejunum of 29-day-old pigs weaned at 21 days of age. Cells were cultured at 37 degrees C for 48 hr in RPMI-1640 medium containing 10 mM D-glucose, 0 to 4 mM L-glutamine, 0 to 5 micrograms/ml ConA, or 20 ng/ml PMA + 375 ng/ml Iono. The medium was also supplemented with 0 or 0.1 mM adenosine, guanosine, inosine, uridine or cytosine to study the effect of nucleosides or bases on IEL proliferation. IEL proliferation was assessed by pulsing with 3H-thymidine for 18 hr. Glutamine metabolism was studied in incubated IEL in the presence of Krebs-Henseleit bicarbonate buffer containing 5 mM D-glucose and 1 mM L-[U-14C]glutamine. PMA+Iono markedly stimulated 3H-thymidine incorporation and glutamine metabolism to ammonia, glutamate, aspartate and CO2. When stimulated by PMA+Iono, rates of 3H-thymidine incorporation and glutamine metabolism were much lower in IEL than in mesenteric lymph node lymphocytes. Glutamine was required for IEL proliferation, and it could not be replaced by adenosine, guanosine, inosine, uridine or cytosine, suggesting that porcine IEL cannot interconvert purine and pyrimidine nucleotides. Porcine IEL poorly or not at all responded to ConA stimulation, in contrast to lymph node lymphocytes, in terms of both [3H]thymidine uptake and glutamine metabolism.
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PMID:Effects of concanavalin A and phorbol myristate acetate on glutamine metabolism and proliferation of porcine intestinal intraepithelial lymphocytes. 875 85

The regulatory effects of angiotensin II (AngII) on its receptor subtypes, AT1 and AT2, were studied using cultured bovine adrenal cells (BAC), which express both receptor subtypes, and PC12W and R3T3 cells, which express only AT2 receptors. In BAC, AngII caused a decrease in AT1- and AT2-binding sites and their corresponding messenger RNAs (mRNAs), but with different kinetics. AT1-binding sites decreased by more than 50% within the first 3 h, whereas AT1 mRNA started to decline after a lag period of 3 h. Both AT2-binding sites and mRNA remained stable within the first 6 h of AngII treatment. Then, AT2 mRNA decreased rapidly with an apparent half-life of 2-3 h, whereas AT2-binding sites declined with an apparent half-life of about 16 h. Measurement of transcription rate and mRNA half-life by the [3H]uridine-thiouridine method revealed that AngII reduced by 90% the rate of AT1 transcription, but had no effect on AT1 mRNA half-life, whereas it slightly reduced AT2 transcription, but markedly reduced AT2 mRNA stability. All of the effects of AngII on both AT1 and AT2 receptors were blocked by losartan, indicating that they were mediated exclusively through the AT1 receptor. In PC12W cells, AngII was unable to modify AT2-binding sites or mRNA. Moreover, in BAC, [125I]AngII was internalized through the AT1 receptor, whereas occupancy of AT2 receptors in either BAC or PC12W did not produce internalization of the hormone. These results indicate that AngII, through the AT1 receptor, down-regulates both AT1 and AT2, but by different mechanisms; AT1 receptor is regulated through internalization-degradation of the occupied receptor and inhibition of transcription, whereas AT2 receptor is regulated mainly by decreasing the stability of its mRNA. Moreover, the phorbol ester phorbol 12-myristate 13-acetate mimicked most of the effects of AngII in BAC and decreased both AT2-binding sites and mRNA on PC12W cells, indicating that the hormonal regulation of both AT1 and AT2 receptors is mediated through protein kinase C activation.
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PMID:Angiotensin II receptor subtypes AT1 and AT2 are down-regulated by angiotensin II through AT1 receptor by different mechanisms. 900 8

The question was addressed whether endothelin-1 (ET-1) exerts hypertrophic effects in cardiomyocytes isolated from ventricles of adult rabbits and maintained in short-term (24 h) serum-free primary culture providing mechanical quiescence. ET-1 (> or =100 pM) increased significantly total mass of cellular protein and incorporation of L-U-[(14)C]phenylalanine and 2-[(14)C]uridine into cellular protein and RNA, respectively. Cycloheximide (35 microM), an inhibitor of protein synthesis, significantly reduced the incorporation of L-U-[(14)C]phenylalanine and 2-[(14)C]uridine into cellular protein and RNA, respectively, under control conditions and in response to ET-1. Actinomycin D (5 microM), a selective inhibitor of transcription, abolished the incorporation of 2-[(14)C]uridine into cellular RNA and significantly reduced the incorporation of L-U-[(14)C]phenylalanine into cellular protein under control conditions and in response to ET-1. The selective antagonists at the ET(A) receptor [BQ123 (100 nM) and PD155080 (100 nM)] and the selective antagonist at the ET(B) receptor [BQ788 (100 nM)] significantly reduced the incorporation of L-U-[(14)C]phenylalanine into cellular protein in response to ET-1 (10 nM). The selective inhibitor of protein kinase C (PKC), bisindolylmaleimide (BIM) (5 microM), reduced markedly the incorporation of 2-[(14)C]uridine into cellular RNA and, to a lesser degree, the incorporation of L-U-[(14)C]phenylalanine into cellular protein in response to ET-1 (100 pM to 10 nM). ET-1 exerts hypertrophic effects directly in vitro in ventricular cardiomyocytes isolated from the hearts of adult rabbits. These effects are (a) due to de novo synthesis since total mass of cellular protein and incorporation of L-U-[(14)C]phenylalanine and 2-[(14)C]uridine into cellular protein and RNA, respectively, were increased; (b) mediated by both the ET(A) and ET(B) receptor subtypes; and (c) may be associated, at least partly, with the activation of PKC.
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PMID:Involvement of endothelin (ET)A and ETB receptors in the hypertrophic effects of ET-1 in rabbit ventricular cardiomyocytes. 912 73

1. Extracellular adenosine 5'-triphosphate (ATP) and uridine 5'-triphosphate (UTP) have been shown to activate a nucleotide receptor (P2U receptor) in rat mesangial cells that mediates phosphoinositide and phosphatidylcholine hydrolysis by phospholipases C and D, respectively. This is followed by an increased activity of the mitogen-activated protein kinase cascade and cell proliferation. Here we show that ATP and UTP potently stimulate the stress-activated protein kinase pathway and phosphorylation of the transcription factor c-Jun. 2. Both nucleotides stimulated a rapid (within 5 min) and concentration-dependent activation of stress-activated protein kinases as measured by the phosphorylation of c-Jun in a solid phase kinase assay. 3. When added at 100 microM the rank order of potency of a series of nucleotide analogues for stimulation of c-Jun phosphorylation was UTP > ATP = UDP = ATP gamma S > 2-methylthio-ATP > beta gamma-imido-ATP = ADP > AMP = UMP = adenosine = uridine. Activation of stress-activated protein kinase activity by ATP and UTP was dose-dependently attenuated by suramin. 4. Down-regulation of protein kinase C-alpha, -delta and -epsilon isoenzymes by 24 h treatment of the cells with 12-O-tetradecanoylphorbol 13-acetate did not inhibit ATP- and UTP-induced activation of c-Jun phosphorylation. Furthermore, the specific protein kinase C inhibitors, CGP 41251 and Ro 31-8220, did not inhibit nucleotide-stimulated c-Jun phosphorylation, suggesting that protein kinase C is not involved in ATP- and UTP-triggered stress-activated protein kinase activation. 5. Pretreatment of the cells with pertussis toxin or the tyrosine kinase inhibitor, genistein, strongly attenuated ATP- and UTP-induced c-Jun phosphorylation. Furthermore, N-acetyl-cysteine completely blocked the activation of stress-activated protein kinase in response to extracellular nucleotide stimulation. 6. In summary, these results suggest that ATP and UTP trigger the activation of the stress-activated protein kinase module in mesangial cells by a pathway independent of protein kinase C but requiring a pertussis toxin-sensitive G-protein and tyrosine kinase activation.
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PMID:Stimulation by extracellular ATP and UTP of the stress-activated protein kinase cascade in rat renal mesangial cells. 913 85

Activation of protein kinase C (PKC) by 12-O-tetradecanoylphorbol-13-acetate (TPA) increased steady-state levels of mRNA encoding the major histocompatibility complex (MHC) class II antigen I-A beta and the class II antigen-associated invariant chain (Ii, CD74) in A20 B lymphoma cells and in normal mouse B cells. The increase in Ii mRNA levels appeared to be due to a slight increase in the rate of gene transcription and an increase in the stability of Ii mRNA. The half-life of Ii mRNA increased from 12 h to >24 h following treatment with TPA, as determined by Northern blot analysis following actinomycin D treatment or by the [3H]-uridine pulse-chase method. Interferon-gamma (IFN-gamma), which has been well characterized as a cytokine that induces class II antigens and the Ii, increased Ii expression slightly in A20 cells. However, cotreatment of cells with TPA and IFN-gamma resulted in a block in the TPA-induced increase in Ii expression. Transcription of the Ii gene was minimally affected following treatment with IFN-gamma alone, and cells treated with both TPA and IFN-gamma had the same transcription rate as the control cells. IFN-gamma did, however, block stabilization of Ii mRNA by TPA. Activation of PKC by TPA, which was previously shown to lead to membrane translocation and downregulation, was not inhibited by IFN-gamma. Therefore, IFN-gamma appeared to block a downstream signal transduction pathway activated by PKC that controls stability of Ii mRNA.
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PMID:Stabilization of invariant chain mRNA by 12-O-tetradecanoylphorbol-13-acetate is blocked by IFN-gamma in a murine B lymphoma cell line. 945 62

The present study was conducted to assess the intracellular signaling pathways mediated by receptors for ATP, uridine triphosphate (UTP), and 2-methylthio ATP (2-MeSATP), by monitoring patch-clamp currents and intracellular calcium mobilization in cultured rat cortical cerebral neurons. All three agonists evoked potassium currents and increased the intracellular free Ca2+ concentration ([Ca2+]i), and these effects were inhibited by the broad G-protein inhibitor guanosine-5'-O-(2-thiodiphosphate) (GDPbetaS) but not by the Gi/o-protein inhibitor pertussis toxin (PTX). UTP-evoked currents were inhibited by either the phospholipase C inhibitor neomycin or the selective protein kinase C (PKC) inhibitor GF109203X, and the rise in cytosolic Ca2+ was inhibited by either neomycin or the inositol 1,4,5-trisphosphate (IP3) receptor antagonist heparin, indicating that the UTP receptor involved phospholipase C-mediated phosphatidylinositol signaling. In contrast, 2-MeSATP-induced currents and rise in cytosolic Ca2+ were not inhibited by either neomycin, or GF109203X, or heparin. 2-MeSATP elicited single-channel currents in the cell-attached patch-clamp configuration and also in excised patches. The G-protein activator GTP gamma S induced single-channel currents in a fashion that mimicked the effect of 2-MeSATP. These data suggest that 2 MeSATP activated potassium channels by a direct action of G-protein beta gamma subunits and increased [Ca2+]i by a mechanism independent of phospholipase C stimulation and IP3 production. ATP-evoked currents were partially inhibited by either neomycin or GF109203X, although the rise in cytosolic Ca2+ was not affected by these inhibitors. ATP produced single-channel currents with two major classes of the slope conductance (86 and 95 pS) in cell-attached patches, each of which is consistent with that achieved by 2-MeSATP (85 pS) or UTP (96 pS); the currents with the lower conductance were observed in the outside-out patch-clamp configuration. These results indicate that P2 receptors for UTP and 2-MeSATP are linked to a PTX-insensitive G-protein involving different signal transduction pathways and that ATP responses are mediated by both of these P2 receptors.
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PMID:Diverse signal transduction pathways mediated by endogenous P2 receptors in cultured rat cerebral cortical neurons. 958 24

1. The ionotropic purinoceptors in isolated Deiters' cells of guinea-pig cochlea were characterized by use of the whole-cell variant of the patch-clamp technique. 2. Extracellular application of adenosine 5'-triphosphate (ATP) induced a dose-dependent inward current when the cells were voltage-clamped at -80 mV. The ATP-induced current showed desensitization and had a reversal potential around -4 mV. 3. Increasing intracellular free Ca2+ by decreasing the concentration of EGTA in the pipette solution reduced the amplitude of the ATP-gated current. 4. The order of agonist potency was: 2-methylthioATP (2-meSATP)>ATP>benzoylbenzoyl-ATP (BzATP)>alpha,beta-methyleneATP (alpha,beta,meATP>adenosine 5'-diphosphate (ADP)>uridine 5'-triphosphate (UTP)>adenosine 5'-monophosphate (AMP)=adenosine (Ad). 5. Pretreatment with forskolin (10 microM), 8-bromoadenosine-3',5'-cyclophosphate (8-Br-cyclic AMP, 1 mM), 3-isobutyl-1-methylxanthine (IBMX, 1 mM) or phorbol-12-myristate-13-acetate (PMA, 1 microM) reversibly reduced the ATP-induced peak current. 6. The results are consistent with molecular biological data which indicate that P2X2 purinoceptors are present in Deiters' cells. In addition, the reduction of the ATP-gated current by activators of protein kinase A and protein kinase C indicates that these P2X2 purinoceptors can be functionally modulated by receptor phosphorylation.
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PMID:P2X receptors in cochlear Deiters' cells. 964 51

To evaluate the role of protein kinase C (PKC) and intracellular calcium and particularly Ca(2+)-uptake in the initiation of lymphocyte mitogenesis, the proliferation of human peripheral blood mononuclear cells (PBMC) was investigated during calcium entry blockade with nifedipine (an L-type calcium channel blocker) and mibefradil (an L- and T-type calcium channel blocker with a higher selectivity for T-type channels). The rate of [3H]-thymidine, [3H]-uridine and [3H]-leucine incorporation into control and concanavalin A-stimulated PBMC cultured for 3 days in the presence or absence of the calcium channel blockers nifedipine or mibefradil (1, 10 or 50 microM) is assayed. Nifedipine and mibefradil concentration-dependently reduced cell number and [3H]-thymidine incorporation or de novo DNA synthesis in control and concanavalin A-stimulated PBMC, as well as de novo RNA and protein synthesis. The proliferative response of nifedipine- or mibefradil-treated cells was restored by addition of phorbol-12-myristate-13-acetate (PMA), an exogenous PKC activator. Our data show that PBMC treated with the Ca2+ channel blockers nifedipine or mibefradil are still capable of proliferating in response to PMA. However, in PKC-depleted cells, the proliferative response of PBMC was suppressed.
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PMID:Proliferation of human peripheral blood mononuclear cells during calcium entry blockade. Role of protein kinase C. 1039 31


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