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 neuroblastoma line SK-N-SH consists of distinct and interconverting cell types, which include a neuroblast phenotype (SH-SY5Y), an epithelial phenotype (SH-EP), and an intermediate cell type (SH-IN). In SH-SY5Y cells, only muscarinic receptor activation produced stimulation of phosphoinositide turnover, whereas in SH-EP cells, where muscarinic receptors are not present, the peptides bradykinin, endothelin, and angiotensin II stimulated phosphoinositide hydrolysis with EC50 values of 16, 6, and 0.7 nM, respectively, and a rank order of maximal effects of bradykinin greater than endothelin greater than angiotensin II. Fetal calf serum at concentrations between 1 and 10% was also a potent stimulator of phosphoinositide hydrolysis in SH-EP cells but not in SH-SY5Y cells. In the intermediate cell clone, SH-IN, phosphoinositide hydrolysis was stimulated not only by muscarinic receptors, but also by endothelin, bradykinin, and serum, an indication that this cell type harbors all the kinds of receptors that are differentially expressed in the other two cell types. The effects of the three peptides--bradykinin, endothelin, and angiotensin II--on phosphoinositide hydrolysis in SH-EP cells were additive, a result suggesting that the three kinds of receptors may activate distinct transducer proteins and/or phospholipase C subtypes. Pretreatment of intact SH-EP cells with pertussis toxin under conditions sufficient to ADP-ribosylate 90-95% of the endogenous guanine nucleotide regulatory protein substrates did not impair the ability of any of the receptors to stimulate phosphoinositide hydrolysis in any of the cell types. In contrast, short-term exposure to the phorbol ester 12-O-tetradecanoylphorbol 13-acetate (1 microM) abolished the stimulation of phosphoinositide hydrolysis mediated by peptide receptors in SH-EP cells and partially inhibited that by muscarinic receptors in SH-SY5Y cells. Prolonged incubation of SH-EP cells with phorbol ester resulted in a recovery of receptor responsiveness, the extent and rate of which were different for each receptor type. In contrast, there was no recovery of responsiveness for muscarinic receptors in SH-SY5Y cells. The pattern of phorbol ester-mediated effects depended on the cell rather than on the receptor type. In fact, muscarinic receptor responsiveness in SH-IN, the intermediate cell type, was desensitized by and recovered from treatment with phorbol esters in a manner more similar to peptide receptors in SH-EP than to muscarinic receptors in SH-SY5Y. These data suggest that the transduction mechanisms by which distinct receptor types are coupled to phosphoinositide hydrolysis in the three cell phenotypes differ in sensitivity to feedback regulation by protein kinase C.
 ...
PMID:The epithelial phenotype of human neuroblastoma cells express bradykinin, endothelin, and angiotensin II receptors that stimulate phosphoinositide hydrolysis. 130 39

Using 3T3 and 3T6 mouse fibroblasts and A431 epidermoid carcinoma cells, we previously observed that extracellular ATP and ADP were mitogens and they synergized with other growth factors (Huang, N., Wang, D. and Heppel, L. A. (1989) Proc. Natl. Acad. Sci. USA 86, 7904-7908). We now report that ATP and ADP stimulated Na+ entry, intracellular alkalinization and Na+/K+ pump activity, which are early events that had been proposed to play a central role in DNA synthesis. In addition, ATP, ADP and AMPPNP stimulated uridine uptake by a pathway involving arachidonic acid metabolism. In A431 cells, activation of protein kinase C also contributed to ATP-dependent stimulation of uridine uptake. Concentrations of indomethacin and pertussis toxin which inhibited uridine uptake also blocked arachidonic acid metabolism and DNA synthesis. ATP acted as a competence factor. Interestingly, ATP did not have to be continuously present to stimulate uridine uptake. It was equally effective even when it was washed away after brief treatment of cells.
 ...
PMID:Extracellular ATP stimulates increases in Na+/K+ pump activity, intracellular pH and uridine uptake in cultures of mammalian cells. 131 Mar 99

Most platelet agonists activate and elevate the cytosolic free calcium concentration in human platelets through receptor-dependent mechanisms that are antagonized by cAMP- and cGMP-elevating agents. Nitrovasodilators such as nitroprusside and endothelium-derived relaxing factor are potent cGMP-elevating platelet inhibitors. In the present study, the role of cGMP and cGMP-dependent protein kinase in nitrovasodilator inhibition of ADP- and thrombin-evoked calcium elevation and activation of human platelets was investigated. Preincubation of platelets with 8-(4-chlorophenylthio)guanosine 3',5'-cyclic monophosphate (8-pCPT-cGMP; a membrane-permeant selective activator of the cGMP-dependent protein kinase that does not significantly affect cGMP-regulated phosphodiesterases) inhibited the thrombin-induced phosphorylation mediated by myosin light chain kinase and protein kinase C. Nitrovasodilator-induced protein phosphorylation in human platelets was distinct from that induced by cAMP-elevating prostaglandins and could be mimicked by 8-pCPT-cGMP. Preincubation of human platelets with nitrovasodilators or 8-pCPT-cGMP inhibited the ADP- and thrombin-evoked calcium elevation in the presence and absence of external calcium. Nitrovasodilators and 8-pCPT-cGMP also inhibited the agonist-induced Mn2+ influx, but stopped-flow experiments indicated that the ADP receptor-operated cation channel was not significantly inhibited. These results suggest that in human platelets nitrovasodilators inhibit the agonist-induced calcium mobilization from intracellular stores and the secondary store-related calcium influx but not the ADP receptor-operated cation channel. The results also suggest that these nitrovasodilator effects are mediated by cGMP and the cGMP-dependent protein kinase.
 ...
PMID:Role of cGMP and cGMP-dependent protein kinase in nitrovasodilator inhibition of agonist-evoked calcium elevation in human platelets. 131 May 37

Platelet-activating factor (PAF) is an unusually potent phospholipid known to be produced by neuronal cells and to modulate cerebral blood flow and metabolism. In previous studies with NCB-20 cells, we reported that PAF induced a significant mobilization of intracellular free Ca2+ ([Ca2+]i), which was inhibited by PAF antagonists. The increase was the result of release from intracellular stores and influx from extracellular sources. The present study was designed to characterize further PAF receptor-mediated cellular signal-transduction mechanisms in myo-[3H]inositol-labeled cells. PAF induced a concentration-dependent increase in phosphatidylinositol (Pl) metabolism, with EC50 values of 1.96 +/- 0.62 nM and 1.12 +/- 0.50 nM for inositol trisphosphate (IP3) and inositol monophosphate (IP1) formation, respectively (four experiments). The maximal production of IP3 and IP1 induced by 50 nM PAF was 254 +/- 34% and 178 +/- 25% over the basal, respectively (four experiments). PAF-induced Pl metabolism was concentration-dependently inhibited by the PAF antagonist BN50739, with an IC50 value of 6.48 +/- 0.52 nM (four experiments). The protein kinase C (PKC) activator phorbol 12,13-dibutyrate concentration-dependently inhibited PAF-induced Pl metabolism and [Ca2+]i mobilization in NCB-20 cells, of NCB-20 cells with pertussis toxin (PTX) resulted in a concentration-dependent inhibition of PAF-induced IP3 production and intracellular Ca2+ release, with a maximal reduction of 66.9 +/- 3.5% and 63 +/- 6.1%, respectively, at 300 ng/ml PTX. PTX in the presence of [32P]NAD specifically [32P]ADP-ribosylated a 38-kDa protein in membranes prepared from NCB-20 cells. Pretreatment of the cells with PTX resulted in a concentration-dependent inhibition of subsequent 32P-labeling of the toxin substrate in the membranes and correlated with the uncoupling of PAF-induced IP3 formation. PAF (0.01-10 nM) elicited a concentration-related stimulation in guanosine 5'-O-(3-[35S]) triphosphate ([35S]GTP gamma S) binding to G alpha i(1,2) proteins, which was inhibited by the PAF antagonist BN50739. PAF at 10 nM also increased [35S]GTP gamma S binding to G alpha s and G alpha o. PAF-evoked activation of G alpha i(1,2) and G alpha o was reduced by preincubation with PTX. Our results reveal that neuronal cells possess PAF receptors linked through guanine nucleotide-binding proteins to phospholipase C and receptor-operated Ca2+ channels that are regulated by PKC. Both PTX-sensitive and -insensitive guanine nucleotide-binding proteins appear to couple the PAF receptor to activation of phospholipase C and the increase in [Ca2+]i. These results contribute to the further understanding of the mechanisms behind PAF actions on neuronal cells.
 ...
PMID:Platelet-activating factor stimulates phosphoinositide turnover in neurohybrid NCB-20 cells: involvement of pertussis toxin-sensitive guanine nucleotide-binding proteins and inhibition by protein kinase C. 131 8

Fructose-1,6-diphosphate (FDP) is a physiological product which exhibits pharmacological properties. This study shows that FDP (1-3 mM) inhibits platelet aggregation induced by the agonists thrombin, vasopressin, platelet activating factor, ADP, adrenaline, arachidonate and the stable thromboxane analogue U 44069. Thrombin-promoted ATP secretion and cytosolic Ca2+ rise are also drastically inhibited by FDP, which decreases, although to a lesser extent, the protein kinase C-dependent phosphorylation of the 47 kDa protein. The inhibition on thrombin-induced aggregation is shared, albeit less efficiently, by glucose-1,6-diphosphate and fructose-2,6-diphosphate but not by other phosphorylated monosaccharides (fructose-1:2 cyclic,6-diphosphate, glucose-1- and glucose-6-phosphate, fructose-1- and fructose-6-phosphate, mannose-6-phosphate and 5-phosphoryl ribose-1-pyrophosphate). FDP does not affect platelet activation induced by the protein kinase C activators dioctanoylglycerol or phorbol 12-myristate 13-acetate. No increase of cAMP concentration is observed in FDP-treated platelets. Altogether, these results indicate that FDP inhibits platelet activation at a level preceding phospholipase C. The data are consistent with a general inhibitory action of FDP on signal transmission.
 ...
PMID:Fructose-1,6-diphosphate inhibits platelet activation. 131 5

Interleukin-1 (IL-1), which plays an important role in the inflammatory response, was found to induce colony-stimulating factor-1 (CSF-1) expression in the MIA PaCa-2 cells. IL-1-induced CSF-1 production was markedly suppressed (70%) by pertussis toxin. This inhibition by pertussis toxin was reversed by benzamide, an inhibitor of ADP-ribosylation reactions. Similarly, IL-1-induced CSF-1 production was inhibited by cholera toxin and this inhibition was reversed by an arginine analog, p-methoxy-benzylaminodecamethylene guanidine sulfate. Dibutyryl-cAMP as well as other cAMP elevating agents such as theophylline and forskolin also suppressed IL-1-induced CSF-1 production, suggesting that cAMP concentrations inversely regulate the biosynthesis of CSF-1. Measurement of cAMP concentration indicated that IL-1 treatment of MIA PaCa-2 cells did not change the cAMP level. IL-1-induced CSF-1 production was not suppressed by the protein kinase C (PKC) inhibitor, H7, under conditions in which 12-O-tetradecanoylphorbol-13-acetate-induced CSF-1 production was completely abolished. These data suggest that IL-1-induced CSF-1 production is not mediated via the activation of PKC. Analysis of oncogene c-fos and c-jun expression has shown the enhancement of expression of both protooncogenes prior to CSF-1, suggesting that the expression of these two oncogenes may be the mechanism which triggers CSF-1 gene expression.
 ...
PMID:Stimulation of macrophage colony-stimulating factor synthesis by interleukin-1. 131 5

We examined changes in guanosine triphosphate-dependent signal transduction mechanisms in the retina from the early stages of the streptozotocin-diabetic rat, a model for Type 1 (insulin-dependent) diabetes mellitus. Guanosine triphosphate binding, guanosine triphosphatase activity, and binding of (azido) guanosine triphosphate decreased significantly in the retina as early as 2 weeks after the induction of diabetes. The ability of guanosine triphosphate to inhibit forskolin-stimulatable adenyl cyclase was also abolished. These data suggest functional deterioration of G-proteins, especially Gi, in diabetic retina. Further studies using retinal rod outer segments revealed deterioration in light-sensitive, guanosine triphosphate-dependent functions of transducin in diabetic rats. Pertussis toxin-catalysed ADP ribosylation of the alpha subunit of transducin, a heterotrimeric G-protein of rod outer segments, was also reduced in diabetes. No functional effects were seen in purified subunits of transducin subjected to non-enzymatic glycation in vitro. On the other hand, incubation of non-diabetic rod outer segments with (12-0-tetradeconyl) phorbol-13-acetate, a protein kinase C agonist, in the presence of magnesium and adenosine triphosphate resulted in the reduction of guanosine triphosphate-binding and hydrolysis, thus indicating that protein kinase C may be involved in the regulation of these activities. The significance of these observations in the early visual abnormalities associated with diabetes is discussed.
 ...
PMID:Functional alterations of G-proteins in diabetic rat retina: a possible explanation for the early visual abnormalities in diabetes mellitus. 132 50

Preincubation of human peripheral blood polymorphonuclear leukocytes (HPPMN) with recombinant human tumor necrosis factor-alpha (rHuTNF-alpha) enhanced the formylmethionyl-leucylphenylalanine (FMLP)-induced superoxide (O2-.) generation in a concentration- and preincubation time-dependent manner. The enhancement was very high for the FMLP- or opsonized zymosan (OZ)-induced O2-. generation, but was low for arachidonic acid (AA)- and phorbol myristate acetate (PMA)-induced O.2- generation. The rHuTNF-alpha has no effect on the steady state of intracellular calcium ion concentration ([Ca2+]i) nor on the membrane potential of neutrophils. The rHuTNF-alpha-primed FMLP-induced O2-. generation was inhibited by nicotineamide (NA), pertussis toxin (PT), and by the tyrosine kinase (TK) inhibitor, genistein, but was enhanced by the protein kinase C (PKC) inhibitor, H-7 (1-(5-isoquinolinesulfonyl)-3-methyl-piperazine). The inhibitory actions of NA and PT were also observed in in vivo primed guinea pig peritoneal neutrophils (GPtPMN). However, FMLP-induced O2-. generation of GPtPMN was enhanced by genistein, but was inhibited by H-7. These data indicate that TNF-alpha does not induce changes in [Ca2+]i nor in membrane potential of HPPMN, and that TNF-alpha-primed FMLP-induced O.2- generation of HPPMN is coupled with ADP-ribosylation and activation of G-proteins, and that protein kinases, especially TK, seem to exert an important role in the priming action of TNF.
 ...
PMID:Effect of tumor necrosis factor-alpha on the stimulus-coupled responses of neutrophils and their modulation by various inhibitors. 132 5

1. Endothelin-1 (ET-1)-induced contraction of porcine coronary artery strips may be mediated via at least two intracellular signalling mechanisms, the activation of dihydropyridine-sensitive voltage-dependent Ca2+ channels and the stimulation of phosphoinositide breakdown. Here we have investigated the possible involvement of pertussis toxin (PT)-sensitive guanosine-5'-triphosphate (GTP)-binding proteins (G-proteins) in ET-1-induced activation of these two signalling pathways in porcine coronary artery smooth muscle. 2. Increase in extracellular K+ concentration (10, 15 mM) shifted the dose-response relationship for the ET-1-induced contraction to the left. 3. The dihydropyridine Ca2+ channel blocker, nifedipine (10(-8) M), induced a rightward shift in the dose-response curve for ET-1. Pretreatment of the arterial strips with PT (0.1 microgram ml-1) induced a similar rightward shift of the ET-1 dose-response curve but not of the KCl response. Nifedipine (10(-8) M) did not further attenuate the ET-1-induced contraction in the PT-pretreated strips. 4. The pretreatment with PT significantly reduced 45Ca2+ uptake of the arterial strips stimulated by ET-1, but had no effect on ET-1-induced production of inositol phosphates. 5. The contractile response of the arterial strips to phorbol dibutyrate, an active phorbol ester, was not significantly affected by 10(-8) M nifedipine. 6. We confirmed that the pretreatment of the tissue with PT induced ADP-ribosylation of a 41 kDa membrane protein. 7. These findings indicate that activation of dihydropyridine-sensitive voltage-dependent Ca2+ channels by ET-1 in this tissue is mediated via a PT-sensitive G-protein in a manner apparently independent of the ET-1-induced activation of protein kinase C. It is concluded that the action of ET-1 in porcine coronary artery is mediated via two distinct signal transduction pathways, which are coupled to PT-sensitive and PT-insensitive GTP-binding proteins, respectively.
 ...
PMID:A pertussis toxin-sensitive mechanism of endothelin action in porcine coronary artery smooth muscle. 133 Jan 78

Metabotropic glutamate receptor (mGluR) is highly expressed in cerebellar Purkinje cells. The purpose of this study was pharmacological and immunocytochemical characterization of the mGluR in single cerebellar neurons, especially Purkinje cells. Ca2+ imaging with fura-2 in cultured cerebellar neurons, identified immunocytochemically, was used to record the direct effects of drugs in stable conditions. In addition, the expression of mGluR was examined, and expression of the intracellular receptor for inositol trisphosphate (IP3) produced by mGluR activation was studied immunocytochemically with specific antibodies. Purkinje neurons and some other neurons showed Ca(2+)-mobilizing responses to mGluR agonists. These responses were mediated by mGluR because they were not blocked by ionotropic GluR antagonists, were independent of the caffeine-sensitive Ca2+ pool, and were blocked by inhibitors of IP3-induced Ca2+ release. This is the first pharmacological characterization of mGluR at single Purkinje cells. The results differed as follows from those in earlier studies in which phosphoinositide turnover of the entire population of cerebellar cells was monitored: (1) the mGluR responses were not blocked by pertussis toxin or D,L-2-amino-3-phosphonopropionic acid; (2) glutamate was a potent agonist, whereas L-aspartate was ineffective; and (3) the dose-response relationship showed an all-or-none tendency. The metaboltropic response of Purkinje cells changed markedly during development, with a sharp peak after day 4 of culture, whereas mGluR and IP3 receptor proteins increased steadily during maturation. This apparent desensitization of mGluR was not blocked by inhibitors of protein kinase C (PKC) or ADP-ribosyltransferase. The metabotropic responses were mainly localized to the center of the somata of Purkinje cells even on day 4, whereas both receptor proteins were expressed throughout the cell. These results suggest that the function of mGluR is spatially and developmentally controlled by a posttranslational mechanism involving a mechanism other than phosphorylation by PKC or ADP-ribosylation.
 ...
PMID:Pharmacological and immunocytochemical characterization of metabotropic glutamate receptors in cultured Purkinje cells. 133 61


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