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 individual and combined effects of dietary toasted soybean meal (3.13-25%) and dietary licorice root extract (0.38-3.0%) on selected liver and intestinal enzyme levels and on clinical chemistry and histopathological parameters were evaluated on male F344 rats. All parameters were measured one and three months after the 50-day-old rats were started on the diets. By use of newly developed high-performance liquid chromatography-based analytic methods, measurable levels of daidzein (2.67 micrograms/ml) and glycyrrhetinic acid (7.87 micrograms/ml) were detected in the sera of rats on the 25% soybean and 3% licorice diets, respectively. Histopathological evaluations of organs and tissues yielded only nonsignificant strain-related changes. At all dosages, there were no significant soybean- or licorice-related anatomic lesions or hematologic changes. In the clinical biochemistry profile, soybean meal caused moderate but significant dose-dependent decreases in serum cholesterol and increases in alkaline phosphatase, blood urea nitrogen, and phosphorus, which remained within the normal range. Liver glutathione transferase, catalase, and protein kinase C showed significant inductions (up to 50%) in response to increasing doses of soybean meal and licorice extract, with evidence for only marginal interaction between the two additives. Their effects on the intestinal mucosa were not significant. Ornithine decarboxylase levels, an indicator of promotional activity, were unchanged or repressed by the additives. The favorable effects of up to 25% toasted soybean meal and 3% licorice root extract on the levels of the four enzymes, without unfavorable changes in clinical parameters, might account in part for the chemopreventive activities of these additives. These effects would be in addition to direct inhibitory effects of known components in these additives on these or other enzymes or modulation of hormone activity that is not evaluated in this study.
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PMID:Effect of dietary soybean and licorice on the male F344 rat: an integrated study of some parameters relevant to cancer chemoprevention. 129 95

A large number of PKC inhibitors are positively charged. We evaluated the structural features of cationic amphiphiles which are necessary for inhibiting PKC. Many of these compounds were derivatives of cholesterol, which possesses a hydrophobic backbone which does not perturb hydrocarbon packing in membrane bilayers. In addition, they contain a tertiary or quaternary nitrogen functionality in the head group. All designed cholesterol-based amphiphiles inhibit PKC activity; the potency of the amphiphile correlates with the presence of positive charge. Quaternary ammonium amphiphiles are 10-fold more potent than their tertiary amine counterparts, generally inhibiting in the 10-60 microM range using the Triton mixed micelle assay. Aside from charge, factors such as the structure of the amine-containing head group, its length from the hydrocarbon moiety, or the number of amine groups on the amphiphile did not markedly influence inhibitor potency. In contrast, the hydrocarbon backbone did influence potency: cationic amphiphiles containing a steroid backbone were more potent inhibitors of PKC than their straight-chain analogues. Changing the nature of the hydrocarbon from a sterol to an alkyl group lowers the pK of the amine head group so that the straight-chain analogues are no longer cationic in the conditions in the PKC assay. The results of these studies suggest that a combination of positive charge and a bilayer-stabilizing structural characteristic provides a basis for the rational design of PKC inhibitors.
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PMID:Inhibition of protein kinase C by cationic amphiphiles. 139 Jun 89

We recently reported that nitrogen dioxide (NO2), an environmental oxidant, alters the dynamics of the plasma membrane lipid bilayer structure, resulting in increased phosphatidylserine content and angiotensin II (Ang II) receptor binding. Angiotensin II is known to elicit receptor-mediated stimulation of diacylglycerol (DAG) production in pulmonary artery endothelial cells. Because protein kinase C (PKC) is a phosphatidylserine-dependent enzyme and is activated by DAG, we examined whether NO2 resulted in activation and/or translocation of PKC from predominantly cytosolic to membrane fractions of these cells. We also evaluated whether NO2 exposure resulted in increased production of DAG in pulmonary artery endothelial cells. Exposure to 5 ppm NO2 for 1-24 hr resulted in significant increases in PKC activity in the cytosolic and membrane fractions (p less than 0.05 for both fractions) compared to activities in control fractions. Exposure to Ang II resulted in translocation of PKC activity from cytosol to membrane fractions of both control and NO2-exposed cells. This translocation of PKC from cytosolic to membrane fraction was prevented by the specific receptor antagonist [Sar1 Ile8] Ang II. Exposure of 5 ppm NO2 for 1-24 hr provoked rapid increases in [3H]glycerol labeling of DAG in pulmonary artery endothelial cells. These results demonstrate that exposure to NO2 increases the production of second messenger DAG and activates PKC in both the cytosolic and membrane fractions, whereas Ang II stimulates the redistribution of PKC from cytosolic to membrane fractions of pulmonary artery endothelial cells.
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PMID:Oxidant and angiotensin II-induced subcellular translocation of protein kinase C in pulmonary artery endothelial cells. 140 42

The effect of hypoxia on the incorporation of [14C]serine into serine glycerophospholipids was investigated in rat brain cortex. Brain slices were incubated, in the presence of the labeled precursor, in Krebs-Henseleit Ringer bicarbonate or Krebs Ringer phosphate, and hypoxia was induced by bubbling nitrogen in the medium. The lowering of oxygen caused an increase of the incorporation of the base into phosphatidylserine in slices incubated in both media, although the effect was greater in Krebs Ringer phosphate. Such an effect was also observed in the homogenate subjected to N2-treatment, with an increase in the incorporation similar to that obtained in slices incubated in Krebs-Henseleit Ringer bicarbonate. Phosphatidylserine is synthesized in mammalian tissues by a "base-exchange" enzyme, strictly Ca2+ dependent, and, moreover, is necessary for protein kinase C activity. We postulate that the increased synthesis of phosphatidylserine might affect signal transduction mechanisms and participate in the modification of lipid metabolism observed in hypoxia and/or ischemia.
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PMID:Serine incorporation into phosphatidylserine in hypoxic rat brain cortex. 149 81

We investigated the effects of seven isoquinoline derivatives in overcoming resistance to vinblastine in Adriamycin-resistant mouse leukemia P388/ADR cells and human myelogeneous leukemia K562/ADR cells. N-(2-Methylpiperazyl)-5-isoquinoline-sulfonamide (H-7), N-[2-(methylamino)ethyl]-5-isoquinolinesulfonamide (H-8), and N-(2-aminoethyl)-5-isoquinolinesulfonamide (H-9) did not reverse resistance to vinblastine in these resistant cells. N-[2-[N-[3-(4-Chlorophenyl)-2-propenyl]amino]ethyl]-5- isoquinolinesulfonamide (H-86) and N-[2-[N-[3-(4-chlorophenyl)-1-methyl-2-propenyl]- amino]ethyl]-5-isoquinolinesulfonamide (H-87) caused significant accumulation of intracellular vinblastine and marked reversal of the resistance to vinblastine in both resistant cell lines. Addition of a formyl group at the terminal amino group of H-86 (H-85) or addition of an aminoethyl group to the nitrogen atom at the sulfonamide group of H-86 (W-66) reduced those activities. The activity on vinblastine accumulation seems to correlated with the hydrophobicity of the compounds. The compounds that effectively reversed resistance to vinblastine inhibited [3H]vinblastine efflux and photoaffinity labeling of P-glycoprotein with a photosensitive analogue of vinblastine, N-(p-azido-(3-[125I]iodo)-salicyl)-N'-beta-aminoethylvindesine. Although these isoquinoline derivatives inhibited protein kinase A and protein kinase C with various potencies, these inhibitory activities did not correlate with the reversal of drug resistance. These results indicate that hydrophobic isoquinoline derivatives reverse multidrug resistance due to the suppression of drug binding to P-glycoprotein, without involvement of their activities on protein kinase A and protein kinase C.
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PMID:Overcoming of vinblastine resistance by isoquinolinesulfonamide compounds in adriamycin-resistant leukemia cells. 161 7

We synthesized the zwitterionic amphiphile cholesterylphosphorylethylpyridinium. This substance activated protein kinase C (PKC) in a micelle-based assay, but in a vesicle assay it was inhibitory. An analog of this compound, in which the pyridine ring is saturated and the nitrogen methylated, showed similar behaviour with PKC. Replacing cholesterol by an aliphatic alcohol lowered the extent of activation in the micelle assay. These results demonstrate that, with some membrane additives, the vesicle and micelle assays give opposite results. Results from the membrane-based vesicle assay for PKC are in accord with the generalization that zwitterionic amphiphiles that raise the bilayer to hexagonal phase transition temperature in model membranes are inhibitors of PKC.
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PMID:Zwitterionic amphiphiles that raise the bilayer to hexagonal phase transition temperature inhibit protein kinase C. The exception that proves the rule. 161 30

Metal ion coordination in the regulatory domain of protein kinase C (PKC) is suggested by the conservation of six cysteines and two histidines in two homologous regions found therein. By monitoring x-ray fluorescence from a purified sample of rat PKC beta I overexpressed in insect cells, direct evidence has been obtained that PKC beta I tightly binds four zinc ions (Zn2+) per molecule. Extended x-ray absorption fine structure (EXAFS) data are best fit by an average Zn2+ coordination of one nitrogen and three sulfur atoms. Of the plausible Zn2+ coordination models, only those featuring nonbridged Zn2+ sites accommodate the EXAFS data and all of the conserved potential ligands.
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PMID:Identification and characterization of zinc binding sites in protein kinase C. 176 27

Insulin (63 microM) stimulated endogenous dopamine (DA) release from tuberoinfundibular neurons. This effect was independent on the presence of extracellular glucose and did not involve the outward transport of DA, mediated by its membrane carrier. By contrast this effect was completely prevented by the removal of extracellular Ca++ ions in presence of the Ca(++)-chelator ethyleneglycol-2-(2-aminoethyl)-tetracetic acid (EGTA). Furthermore 1-(5-isoquinolinyl-sulfonyl)-2-methyl-piperazine (H7), a compound which behaves as a putative inhibitor of protein kinase C (PK-C) (10 microM), completely counteracted the stimulation of endogenous DA release induced by insulin. Amiloride (300 microM) and its 5-amino nitrogen atom-substituted derivative, 5-(N-methyl-N-(guanidinocarbonylmethyl) amiloride (MGCMA) (10 microM), a highly selective inhibitor of the Na(+)-H+ membrane antiporter, were both able to prevent the stimulatory action exerted by insulin on endogenous DA release. Collectively, these results suggest that the transductional events by which insulin stimulated endogenous DA release from TIDA neurons may involve the activation of PK-C, the enhancement of Ca++ influx and the stimulation of the Na(+)-H+ exchange system.
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PMID:Possible involvement of Ca++ ions, protein kinase C and Na(+)-H+ antiporter in insulin-induced endogenous dopamine release from tuberoinfundibular neurons. 215 21

The subcellular localization of protein kinase C in unstimulated human neutrophils and neutrophils stimulated by phorbol-myristate-acetate (PMA), 1-oleoyl-2-acetyl-rac-glycerol (OAG), and ionomycin was investigated in subcellular fractions obtained by nitrogen cavitation and Percoll density gradient centrifugation. Protein kinase C was found to be localized mainly in the cytosol in unstimulated cells, whereas significant translocation to fractions containing the plasma membrane was observed after stimulation by PMA, OAG, and ionomycin. At the same time, phospholipid-insensitive protein kinase activity appeared in the cytosol and the plasma membrane fractions. To determine whether binding of protein kinase C occurred to the plasma membrane or to intracellular membranes that had translocated to the plasma membrane, we investigated the ability of isolated azurophil, specific and secretory granules, and plasma membrane vesicles to bind protein kinase C in response to addition of PMA and OAG. Only fractions containing plasma membranes and secretory granules were able to bind protein kinase C. The observation explains the selective activation of plasma membrane structures by protein kinase C.
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PMID:Translocation of protein kinase C to subcellular fractions of human neutrophils. 271 84

Ca2+-dependent myosin phosphorylation by Ca2+/calmodulin-dependent myosin light chain kinase (MLC-kinase) and protein kinase C were studied using selective inhibitors, isoquinolinesulfonamide derivatives. Both protein kinases were potently inhibited by 1-(8-chloro-5-isoquinolinesulfonyl)piperazine (HA-156) and its derivatives. Kinetic analysis indicated that HA-156 inhibited both enzymes competitively with respect to ATP, and Ki values of HA-156 for MLC-kinase and protein kinase C were 7.3 and 7.2 microM, respectively. To clarify molecular mechanisms of the isoquinolinesulfonamides to inhibit the Ca2+-dependent protein kinases, we examined the structure-activity relationships of HA-156 and its derivatives. The dechlorinated analogues, HA-100 and HA-142, markedly decreased the affinity for MLC-kinase, suggesting that the inhibitory effect of isoquinolinesulfonamide derivatives depends upon hydrophobicity of the compounds. There is a good correlation between MLC-kinase inhibition and hydrophobicity determined by reverse phase chromatography. In contrast, HA-140 and HA-142 showed weak inhibition of protein kinase C, suggesting that the electron density of the nitrogen in the isoquinoline ring of the compounds correlates with the potency to inhibit protein kinase C activity. These pairs of isoquinolinesulfonamides will aid in elucidating the biological roles of Ca2+-dependent myosin phosphorylation in intact cells. HA-156 and HA-140 inhibited myosin light chain phosphorylation in platelets exposed to collagen, whereas HA-142 and HA-100 did not, significantly. These isoquinolinesulfonamide derivatives should prove to be useful tools for distinguishing between the biological functions of Ca2+-activated, phospholipid-dependent, and Ca2+/calmodulin-dependent myosin light chain phosphorylation, in vivo.
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PMID:Selective modulation of calcium-dependent myosin phosphorylation by novel protein kinase inhibitors, isoquinolinesulfonamide derivatives. 295 13


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