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)

To evaluate the role of reactive oxygen species (ROS) in Shigella dysenteriae 1 toxin (STx) mediated intestinal infection, the ligated rabbit small intestinal loops were injected with STx. The enterocytes isolated from STx treated rabbit ileal loops had a significantly higher level of lipid peroxidation as compared to enterocytes isolated from control rabbit ileum. To study the role of second messengers in STx mediated intestinal damage, the in vivo and in vitro effects of modulators of lipid peroxidation of enterocytes were used. The presence of Ca2+-ionophore A23187 enhanced the extent of lipid peroxidation in enterocytes isolated from the control and STx treated rabbit ileum. However, 1-verapamil only marginally decreased the lipid peroxidation level of enterocytes isolated from STx treated rabbit ileum. The in vitro effect of modulators was in agreement with in vivo studies. Dantrolene significantly decreased the extent of lipid peroxidation of enterocytes isolated from STx treated rabbit ileum. PMA significantly increased the lipid peroxidation level of enterocytes isolated from control ileum. However, PMA could not further enhance the lipid peroxidation level of enterocytes isolated from STx treated rabbit ileum. The presence of H-7 significantly decreased the extent of lipid peroxidation of enterocytes isolated from STx treated rabbit ileum. In vitro effect of PMA and H-7 was in agreement with that of in vivo findings. The role of arachidonic acid metabolites, prostaglandins (PGs), in mediating STx induced lipid peroxidation was also studied. The presence of indomethacin (a PG synthesis inhibitor) significantly decreased the lipid peroxidation induced by STx. These findings suggest that lipid peroxidation induced by STx is mediated through cytosolic calcium. The increase in (Ca2+)i leads to activation of PKC. A significant decrease in the enterocyte levels of antioxidant enzymes superoxide dismutase, catalase and reduced glutathione in STx treated rabbit ileum as compared to control was seen. A significant decrease in vitamin E levels was also observed. This suggests that there is decreased endogenous intestinal protection against ROS in STx mediated intestinal infection which could contribute to enterocyte membrane damage that ultimately leads to changes in membrane permeability and thus to fluid secretion.
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PMID:Shigella dysenteriae type 1 toxin induced lipid peroxidation in enterocytes isolated from rabbit ileum. 954 97

We have examined the effects of three structurally distinct antioxidants (N-acetylcysteine [NAC], Trolox C [a water-soluble vitamin E derivative], and nordihydroguaiaretic acid [NGA]) on the expression of the c-fos gene over a 2-hour period. Determination of cellular glutathione concentration (the primary determinant of the cellular redox state) over the same time-course verifies that all the compounds studied cause an increase in cellular reduction potential. The level of c-fos messenger RNA increased rapidly in response to micromolar concentrations of these compounds, reaching a peak in 30-60 minutes. Induction of c-fos expression by these antioxidants is at least partly due to an increase in transcription, as determined by nuclear run-on assay. Down regulation of protein kinase C (PKC) by pretreatment for 24 hours with 500 nm PMA prevents induction by subsequent stimulation with either PMA or NGA. NAC induction of c-fos is unaffected by PMA pretreatment, while Trolox C superinduced c-fos following PMA pretreatment. None of these treatments stimulated translocation of PKC-alpha from the cytosol to the membrane. These results suggest that increasing the intracellular reducing potential induces c-fos expression through multiple pathways.
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PMID:Antioxidants stimulate transcriptional activation of the c-fos gene by multiple pathways in human fetal lung fibroblasts (WI-38). 969 15

Troglitazone and pioglitazone, antidiabetic thiazolidinediones, are known to improve insulin resistance. However, the effect of these drugs on platelet aggregation remains unclear. The chemical structure of troglitazone contains vitamin E. Accordingly, we studied the effect of troglitazone, pioglitazone, and vitamin E on thrombin-induced platelet aggregation, metabolism of phosphoinositide, protein phosphorylation, protein kinase C (PKC)-alpha and -beta, and phosphatidylinositol (PI) 3-kinase activation in vitro in human platelets. Maximum platelet aggregation by ADP, collagen, and thrombin decreased in the presence of 0.1-1 micromol/l troglitazone and 500 nmol/l vitamin E for 60 min compared with controls. However, pioglitazone did not inhibit ADP-, collagen-, or thrombin-induced platelet aggregation. Pretreatment with troglitazone and vitamin E, but not with pioglitazone, resulted in decreases in thrombin-induced phosphatidic acid production, hydrolysis of phosphatidylinositol 4,5-bisphosphate by phospholipase C, and 47-kDa protein phosphorylation. Thrombin-induced PKC-alpha and -beta activation in membrane fraction was suppressed by pretreatment with troglitazone and vitamin E, but not with pioglitazone. Separately, troglitazone and pioglitazone stimulated PI 3-kinase activity, but thrombin-induced PI 3-kinase activation was suppressed by pretreatment with troglitazone and pioglitazone for 60 min. These results suggest that troglitazone and vitamin E, but not pioglitazone, have a potent inhibitory effect on platelet aggregation via suppression of the thrombin-induced activation of phosphoinositide signaling in human platelets. Finally, the chemical structure of vitamin E may contribute to the inhibitory effect of troglitazone on platelet aggregation in human platelets.
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PMID:Differential effect of the antidiabetic thiazolidinediones troglitazone and pioglitazone on human platelet aggregation mechanism. 972 40

Numerous articles and several reviews have been published on the role of antioxidants, and diet and lifestyle modifications in cancer prevention. However, the potential role of these factors in the management of human cancer have been largely ignored. Extensive in vitro studies and limited in vivo studies have revealed that individual antioxidants such as vitamin A (retinoids), vitamin E (primarily alpha-tocopheryl succinate), vitamin C (primarily sodium ascorbate) and carotenoids (primarily polar carotenoids) induce cell differentiation and growth inhibition to various degrees in rodent and human cancer cells by complex mechanisms. The proposed mechanisms for these effects include inhibition of protein kinase C activity, prostaglandin E1-stimulated adenylate cyclase activity, expression of c-myc, H-ras, and a transcription factor (E2F), and induction of transforming growth factor-beta and p21 genes. Furthermore, antioxidant vitamins individually or in combination enhance the growth-inhibitory effects of x-irradiation, chemotherapeutic agents, hyperthermia, and biological response modifiers on tumor cells, primarily in vitro. These vitamins, individually, also reduce the toxicity of several standard tumor therapeutic agents on normal cells. Low fat and high fiber diets can further enhance the efficacy of standard cancer therapeutic agents; the proposed mechanisms for these effects include the production of increased levels of butyric acid and binding of potential mutagens in the gastrointestinal tract by high fiber and reduced levels of growth promoting agents such as prostaglandins, certain fatty acids and estrogen by low fat. We propose, therefore, a working hypothesis that multiple antioxidant vitamin supplements together with diet and lifestyle modifications may improve the efficacy of standard and experimental cancer therapies.
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PMID:High doses of multiple antioxidant vitamins: essential ingredients in improving the efficacy of standard cancer therapy. 1006 54

We studied the potential neuroprotective action of nicergoline in immortalized hypothalamic GT1-7 cells exposed to agents which deplete levels of reduced glutathione, thus causing oxidative stress and cell death. Treatment with diethylmaleate (1 mM), buthionine sulfoximine (500 microM) or menadione (10-50 microM) caused diffuse GT1-7 cell degeneration, as assessed by using either the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cytotoxicity assay or the fluorescent dyes fluorescein diacetate and propidium iodide. Pre- and/or co-exposure of the cells to nicergoline significantly prevented diethylmaleate- or buthionine sulfoximine-induced neuronal death, whereas nicergoline was ineffective against menadione-induced toxicity. This effect was concentration-dependent and was mimicked by the classical antioxidants idebenone and vitamin E, and did not depend on interference with protein kinase C. Interestingly, the antineurodegenerative activity of nicergoline and vitamin E or idebenone was not additive, suggesting that these compounds share some intracellular mechanism(s) responsible for their protective effects. In conclusion, the present data indicate that nicergoline has neuroprotective activity, possibly mediated by the antioxidant activity of the molecule, and give support to the potential use of nicergoline in the prevention and therapy of neurodegenerative diseases.
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PMID:Neuroprotective effects of nicergoline in immortalized neurons. 1019 66

Cis-unsaturated fatty acids (c-UFAs) have been shown to be capable of decreasing the survival of macrophage tumor (AK-5) cells in vitro. This cytotoxic action of c-UFAs was found to be associated with an increase in free radical generation and lipid peroxidation process and a simultaneous decrease in cellular anti-oxidants such as superoxide dismutase (SOD), catalase, glutathione peroxidase, glutathione reductase, glutathione and vitamin E. In the present study, it was observed that c-UFAs such as gamma linolenic acid (GLA), arachidonic acid (AA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) can activate phospholipase C (PLC) and enhance diacylglycerol formation; all the fatty acids except alpha linolenic acid (ALA) increased the binding of phorbol dibutyrate acetate (PDBu) suggesting translocation of protein kinase C (PKC) and at the same time these fatty acids (especially GLA, AA, EPA and DHA) also enhanced PKC activity. AA, EPA and DHA decreased the activity of protein kinase A (PKA) both in the cytosol and particulate fractions whereas ALA and GLA enhanced the PKA activity in the particulate fractions; all the fatty acids except ALA reduced cyclic AMP levels and an enhanced phosphorylation of about 13 proteins of the nuclear fraction and about eight proteins of the plasma membrane fraction was noted in c-UFA treated AK-5 cells in vitro. These results suggest that c-UFAs can alter the activities of second messenger systems such as diacylglycerol and protein kinases and can phosphorylate both plasma membrane and nuclear proteins which are likely to be components of NADPH oxidase. Based on these results, it is suggested that fatty acids may mediate their cytotoxic action in part by modulating the expression of PKC. Activated PKC may then intensify the pro-oxidant state by augmenting NADPH oxidase, so inducing superoxide anion generation which may ultimately lead to cytolysis.
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PMID:Effect of cis-unsaturated fatty acids on the activity of protein kinases and protein phosphorylation in macrophage tumor (AK-5) cells in vitro. 1031 18

Considerable epidemiologic data suggest that dietary consumption of vitamin E reduces the incidence of cardiovascular disease. The precise mechanisms are not clear, but emerging data indicate that vitamin E has numerous activities that may, in part, explain its effect on vascular disease. In particular, vitamin E enhances the bioactivity of nitric oxide, inhibits smooth muscle proliferation, and limits platelet aggregation. One common mechanism to account for these effects of vitamin E is the inhibition of protein kinase C stimulation. In the setting of atherosclerosis, inhibition of protein kinase C by vitamin E would be expected to maintain normal vascular homeostasis and thus reduce the clinical incidence of cardiovascular disease.
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PMID:Vitamin E and vascular homeostasis: implications for atherosclerosis. 1033 80

In this work, we have studied the modulation of fibroblast-extracellular matrix interactions by physiological doses of ultraviolet A (UV-A) radiation using an adhesion assay on collagen. We have shown that low doses of UV-A (20 kJ/m2) stimulate fibroblast adhesion while higher doses (100 and 200 kJ/m2) inhibit it. By measurement of the thiobarbituric acid reactive substances (TBARS) and use of the chain-breaking antioxidant vitamin E, no role of lipid peroxidation can be detected in these effects. By incubating fibroblasts with a specific protein kinase C (PKC) inhibitor, GF109203X, we have demonstrated that the stimulation of the adhesion by low doses of UV-A involves, at least in part, a PKC-dependent mechanism. In addition, using function-blocking antibodies of alpha 1, alpha 2 or alpha 5 integrin chains involved in extracellular matrix anchorage, we have shown that they decrease the stimulation of adhesion following low doses of UV-A radiation, demonstrating the involvement of these three integrin chains in this UV-A effect. In parallel, 20 kJ/M2 of UV-A are found to rapidly stimulate membrane expression of alpha 1, alpha 2 and alpha 5 integrin chains. This work, which underlines the involvement of integrins in UV-A effects, contributes to the evaluation of the mechanisms by which cell-matrix interactions modulate cell behaviour.
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PMID:Low doses of ultraviolet A radiation stimulate adhesion of human dermal fibroblasts by integrins in a protein kinase C-dependent pathway. 1039 64

It was shown that vitamin E decreased the stimulating role of oxidative burst activators which influenced on Ca(2+)-dependent mechanisms (A23187, verapamil, FMLP). Jointly addition of this vitamin and blood plasma contained tocopherol-binding proteins influenced on mechanisms associated with protein kinase C. It was shown that Ca ions can also take part in tocopherol's action on blast transformation of lymphocytes.
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PMID:[Role of Ca ions and protein kinase C in the action of vitamin E on respiratory burst of neutrophils and blast transformation of lymphocytes]. 1044 62

Vitamin E has emerged as a major factor in the prevention and inhibition of cardiovascular disease. The inhibition of platelet function, especially adhesion, which is an important event in the development and propagation of cardiovascular disease, plays a crucial role in the beneficial effect that vitamin E exerts on such diseases. Although it is best known for its antioxidant activity, vitamin E interferes with platelet adhesion via a mechanism that is independent of this action. Vitamin E-induced inhibition of protein kinase C leads to decreased platelet pseudopodia formation upon stimulation by agonists, a process that is instrumental in reducing platelet adhesion. In conjunction with potent inhibitors of platelet aggregation, vitamin E has become a widely applied treatment regimen for this group of diseases. Increased bleeding, especially when vitamin E is combined with a potent platelet aggregation inhibitor, has to be considered a side effect of its mechanism of action, but should not detract from the potential benefits for the majority of patients who take this vitamin.
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PMID:Vitamin E, a modifier of platelet function: rationale and use in cardiovascular and cerebrovascular disease. 1057 6


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