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)

We have studied the effect of protein kinase C and protein kinase A activation, and phosphatase inhibition on two different stimuli with distinct mechanisms of action. The first stimulus is compound 48/80, and its action is mediated probably by a Gi-protein, while the other is sodium fluoride, which unspecifically activates G-proteins. We established a comparative study because the action of compound 48/80 is calcium-independent, while fluoride is strictly calcium-dependent. The activation of protein kinase C was attained with the phorbol esther 12-O-tetradecanoylphorbol-13-acetate, protein kinase A was activated by increasing cAMP levels with forskolin or rolipram, and the phosphatase activity was inhibited with okadaic acid (OA), which inhibits phosphatases type 1 and 2A. Our results show that OA enhances the response to fluoride and compound 48/80 in the absence of calcium, and we conclude that calcium has a negative feedback role on the cell response. Protein kinase A activation strongly inhibits the response to fluoride, and the results show a positive regulation of protein kinase C and a negative regulation of protein kinase A over fluoride response. As previously reported by other authors for the ionophore A23187, TPA notably potentiates the response to fluoride, which supports its possible modulatory role on extracellular calcium-dependent stimuli.
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PMID:Influence of protein kinase C, cAMP and phosphatase activity on histamine release produced by compound 48/80 and sodium fluoride on rat mast cells. 128 Sep 5

In vascular smooth muscle cell (VSMC) cultures from Sprague-Dawley (SD) and hypertensive transgenic rats for the mouse renin gene Ren-2 (TGR), the DNA synthesis, which was analyzed by the uptake of [3H]thymidine, was higher in TGR than SD VSMCs (2.5- to 8-fold, mean of 5.6-fold) under basal conditions. DNA synthesis was increased by fetal calf serum (10%) in SD cells more than in TGR VSMCs, and was decreased by heparin (400 micrograms/ml) and by phorbol-12,13-dibutyrate (10(-7) M) in TGR VSMCs to a higher degree than in SD cells. Neither endothelin (10(-7) M), angiotensinogen (10(-8) M), the renin inhibitor CGP 29,287 (10(-4) M), angiotensin I (10(-7) M), captopril (10(-5) M), angiotensin II (10(-7) M), nor saralasin (10(-6) M) modified DNA synthesis in either type of VSMCs. Sodium nitroprusside (10(-4) and 10(-3) M) increased DNA synthesis in both kinds of VSMCs but in TGR cultures it became toxic at 10(-3) M. 8-Bromocyclic GMP (10(-7) to 10(-5) M) reduced DNA synthesis in SD cells more than in TGR VSMCs. These results suggest that (a) cellular mechanisms of proliferation appear to be more activated in TGR VSMCs, likely involving a protein kinase C-dependent pathway but not the renin-angiotensin system, and (b) in both type of cells, sodium nitroprusside possesses proliferative properties whereas 8-bromocyclic GMP has antiproliferative properties.
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PMID:Vascular smooth muscle proliferation in hypertensive transgenic rats. 128 47

Endothelin (ET)-1 and ET-3 induced a biphasic effect (relaxation followed by contraction) in the isolated guinea pig ileum. The contractile but not the relaxant component of the responses was concentration dependent in the dose range studied. Neuronal mechanisms, cyclic guanosine monophosphate (GMP), and adenosine triphosphate (ATP)-dependent K+ channels do not seem to be involved in the relaxing effect of the two isopeptides, since that effect was not affected by either tetrodotoxin, methylene blue, or glibenclamide. Both ET-1 and ET-3 induced tachyphylaxis (homologous desensitization), which was not fully reversed after a 3-h resting period. The responses to both peptides were dependent on the Na+ gradient across the smooth muscle cells, as they were inhibited in low-Na+ medium and after treatment of the preparation with ouabain. Verapamil affected both the relaxant and the contractile components of the responses to the two isopeptides, whereas phorbol-12,13-dibutyrate affected mainly the contractile component. These results suggest that the voltage-operated channels are important for both components of the response induced by ET-1 and ET-3, and that protein kinase C may downregulate Ca2+ signalling. Cross-tachyphylaxis studies between ET-1 and ET-3 suggest the existence of at least two ET receptor subtypes in the guinea pig ileum.
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PMID:Effects of endothelin-1 and endothelin-3 on the isolated guinea pig ileum: role of Na+ ions and endothelin receptor subtypes. 128 81

In myocardial infarction, adrenergic stimulation of the heart is thought to cause cell damage and malignant arrhythmias. In rat hearts as well as in human cardiac tissue, ischemia induces norepinephrine (NE) release, which results in micromolar catecholamine concentrations in the interstitial space of the ischemic myocardium. It has been found that local metabolic, rather than centrally evoked NE release, plays the crucial role in excess adrenergic activation of the ischemic myocardium. NE release in ischemia is nonexocytotic and has been characterized as a two-step process. (a) Induced by energy deficiency, NE escapes from its storage vesicles and accumulates in the axoplasm. (b) NE is transported across the plasma membrane into the extracellular space via the neuronal NE carrier (uptake1), which has reversed its normal transport direction because of increased intracellular sodium concentration. NE release induced by ischemia is independent of the presence of calcium in the extracellular space and is not altered by blockade of N-type (neuronal) calcium channels. Furthermore, modulation of protein kinase C does not interfere with NE liberation in the ischemic myocardium. This independence of extracellular calcium, calcium entry into the neuron, and protein kinase C activity is in contrast to the strong calcium dependence of exocytotic transmitter release, which is found under physiological conditions. On the basis of these findings, it was unexpected that calcium antagonists such as gallopamil, verapamil, diltiazem, felodipine, and nifedipine suppress ischemia-induced NE release. The most potent effect was found for gallopamil with a concentration of 50% inhibition (IC50) of 300 nmol/L.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Calcium antagonism and norepinephrine release in myocardial ischemia. 128 51

The effects of endothelin on intracellular pH (pHi) were examined in cultured rat vascular smooth muscle cells (VSMC) using the fluorescent probe BCECF. Endothelin induced biphasic changes in pHi: initial decrease followed by a subsequent increase above the basal level due to activation of the Na+/H+ exchange. The elevation of pHi was slow and sustained, but depended on the dose of endothelin: IC50 was about 3 x 10(-8) M. Na+/H+ exchange inhibition by EIPA (10(-7) M) or by equimolar replacement of external Na+ by choline abolished the pHi increase by enhancing the first phase of cytoplasm acidification. Effects of endothelin were compared with the action of protein kinase C (PK-C) activator phorbol 12-13 myristate ester (PMA). PMA induced a monophasic slow and sustained increase in pHi. The treatments of VSMC with H-7 and staurosporine (PK-C) inhibitors prevented the pHi response to endothelin and PMA. These results suggest that protein kinase C may play an important role in mediating the effects of endothelin on Na+/H+ exchange in VSMC.
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PMID:[The effect of endothelin-1 on Na+/H+ metabolism in vascular smooth muscle cells]. 129 82

The recently described family of proteins, the endothelins, are produced in neurons and bind to extravascular sites in the CNS. To characterize these receptors, we carried out studies on cultures of fetal rat diencephalic glia. Scatchard analysis of saturation binding studies was done for astrocytes (greater than 95% glial fibrillary acidic protein positive). For endothelin 3 (ET-3) and ET-1, respectively, a single receptor class of KD 0.41 +/- 0.05 and 0.62 +/- 0.04 nM and a receptor density of 42 +/- 0.8 and 58 +/- 1.1 fmol/mg of glial protein was found. Bound and cross-linked 125I-ET-3 or ET-1 showed a single predominant receptor band at Mr 52,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis; a minor band at 50,000 was also seen. At concentrations equal to the receptor KD, the major brain form of ET, ET-3, stimulated a nearly 200% increase in the incorporation of tritiated thymidine into glia. ET-3 and ET-1 significantly impaired the ability of atrial natriuretic peptide (ANP) to generate cyclic GMP, and isoproterenol to generate cyclic AMP. The ability of ET to inhibit ANP-induced cyclic GMP generation was reversed by cycloheximide and actinomycin-D, whereas the inhibition of isoproterenol-induced cyclic AMP generation was partially and significantly blocked by inhibitors of calcium influx, protein kinase C action, or G protein activation, as well. Astrocytes from this part of the brain are a potential target cell for endothelin, assuming these findings are present in vivo. This neuropeptide may serve as a growth stimulator for astrocytes and modulator of the actions of catecholamines or ANP on glia by inhibiting second messenger generation.
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PMID:Endothelin receptors on cultured fetal rat diencephalic glia. 130 67

12-O-Tetradecanoylphorbol-13-acetate (TPA) markedly enhanced the increase in L-histidine decarboxylase (HDC) activity induced by dexamethasone in mouse mastocytoma P-815 cells, even with a concentration of the latter that had the maximal effect, whereas it induced a rapid and transient increase in HDC activity, which peaked after 3 h in the absence of dexamethasone. The synergistic effect of TPA on HDC activity induced by dexamethasone was detected after 4 h, a plateau level being reached by 6 h, which was similar to the time course with dexamethasone alone. TPA enhanced the induction of HDC activity by various glucocorticoids, but had no effect on the induction by dibutyryl cAMP, prostaglandin E2 or sodium butyrate. Both 1-oleoyl-2-acetylglycerol, a protein kinase C activator, and okadaic acid, a protein phosphatase inhibitor, enhanced the increase in HDC activity induced by dexamethasone, but 4 alpha-phorbol-12,13-didecanoate, an inactive derivative of TPA, did not. Protein kinase C inhibitors, such as staurosporin, H-7 and K255a, suppressed the increase in HDC activity induced by TPA with or without dexamethasone. The enhancement of HDC activity by dexamethasone was completely suppressed by cycloheximide or actinomycin D. Furthermore, TPA markedly enhanced the accumulation of HDC mRNA due to dexamethasone (5 to 10-fold, from 6 to 12 h after). TPA did not cause a significant increase in the level of either [3H]dexamethasone binding capacity or preformed HDC activity in cells. These results taken together suggest that dexamethasone-induced de novo synthesis of HDC in mastocytoma P-815 cells is up-regulated by TPA-activated protein kinase C through the mechanism involving an increased rate of transcription.
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PMID:Synergistic effects of 12-O-tetradecanoylphorbol-13-acetate and dexamethasone on de novo synthesis of histidine decarboxylase in mouse mastocytoma P-815 cells. 131 50

Immobilon-bound phosphoproteins labeled with 32P were utilized as substrates to study the enzymes in neutrophils that are active against the major products of protein kinase C. The labeled proteins were separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and transferred electrophoretically to immobilon-P membranes. Both particulate and soluble phosphatases were found to be active against the blotted phosphoproteins. Reactions were followed by autoradiography as the loss of 32P from individual protein bands. The tumor promoter okadaic acid and the hepatoxin microcystin-LR inhibited these reactions in a manner consistent with the enzymes being type 1 and/or 2A protein phosphatases.
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PMID:Utility of immobilon-bound phosphoproteins as substrates for protein phosphatases from neutrophils. 131 56

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.
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PMID:Extracellular ATP stimulates increases in Na+/K+ pump activity, intracellular pH and uridine uptake in cultures of mammalian cells. 131 Mar 99

The Na+/H+ exchanger is a pH-regulatory protein that extrudes one H+ ion in exchange for one Na+ ion when intracellular pH declines. A number of studies have shown phorbol ester stimulation of activity in intact cells, leading to the idea that the exchanger is regulated by protein kinase C-mediated phosphorylation in vivo. cDNA encoding the protein has been cloned, and a recent model suggests a large internal cytoplasmic C-terminal domain that may be a site of regulation of the exchanger [Sardet, Franchi & Pouyssegur (1989) Cell 56, 271-280]. We examined this region of the protein using a rabbit cardiac Na+/H+ exchanger cDNA clone. cDNA of the Na+/H+ exchanger, coding for the C-terminal 178 amino acid residues, was cloned into the expression vector pEX-1 and expressed as a fusion protein with beta-galactosidase. The fusion protein reacted with an antibody produced against a synthetic peptide of the C-terminal 13 amino acid residues of the Na+/H+ exchanger, confirming the identity of the expressed protein. Control and experimental pEX-1-Na+/H+ exchanger protein was purified on a p-aminophenyl beta-D-thiogalactopyranoside-agarose column. Purified Ca2+/calmodulin-dependent protein kinase II readily phosphorylated the Na+/H+ exchanger protein in a Ca(2+)- and calmodulin-dependent manner in vitro, but this region of the protein was not a substrate for purified protein kinase C or for the catalytic subunit of cyclic AMP-dependent protein kinase. Control-expressed beta-galactosidase was phosphorylated to a maximal level of 0.77 +/- 0.17 mol of Pi/mol (mean +/- S.E.M., n = 6) whereas the fusion protein was phosphorylated to a maximal level of 4.09 +/- 0.39 mol of Pi/mol (n = 6), suggesting one site of phosphorylation in beta-galactosidase and three in the C-terminal domain of the Na+/H+ exchanger. Examination of the deduced amino acid sequence of this part of the exchanger reveals three consensus sequences for Ca2+/calmodulin-dependent protein kinase II. These results suggest that the exchanger may be directly regulated in vivo by calmodulin-dependent protein kinase II but not by protein kinase C or cyclic AMP-dependent protein kinase.
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PMID:Phosphorylation of the C-terminal domain of the Na+/H+ exchanger by Ca2+/calmodulin-dependent protein kinase II. 131 52


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