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 found that 4-beta-phorbol 12-myristate 13-acetate (PMA) caused decreased expression of the polymorphonuclear neutrophil (PMN) surface antigen 31D8. In contrast to the rapid initiation of the oxidative burst caused by PMA, the effect was slow to start but increased during incubation periods up to 50 min. To study this apparent protein kinase C-independent late effect of PMA, we measured 31D8 expression in PMNs after incubation with various concentrations of PMA. The maximum PMA-induced inhibition was 76 +/- 2%, with an ID50 of 3.9 +/- 0.4 ng/ml. Oxidants and prooxidants (hydrogen peroxide, hypochlorite, taurine-chloramine, and ferrous iron, with or without H2O2) had no direct effect on 31D8 antigen expression. The following substances were not protective against the inhibitory affect of PMA: (1) antioxidants (superoxide dismutase, catalase, azide, dimethyl sulfoxide, Desferal, and ascorbate, with the exception of alpha-tocopherol), (2) inhibitors of protein kinase C (H7 and W7), (3) inhibitors of 5-lipoxygenase (A-63162, MK886, and high-dose indomethacin) and (4) inhibitors of cyclooxygenase (low-dose indomethacin). Myeloperoxidase-deficient PMNs had normal 31D8 antigen expression and a decrease of 31D8 antigen expression by PMA, as did normal PMNs. The inactive analog of PMA, 4-alpha-phorbol didecanoate, had no effect on 31D8 antigen expression. alpha-Tocopherol (50 micrograms/ml) and betamethasone (150 micrograms/ml) protected against the PMA effect by 30.5 +/- 7.3 (P less than .0005) and 52 +/- 15 (P less than 0.004) channels, respectively. These results indicate that PMA has a protein kinase C-independent late effect on human neutrophils, which can be prevented by pretreatment with alpha-tocopherol or the steroid betamethasone. These compounds probably exert their protective effect by membrane stabilization.
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PMID:Characterization of a direct effect of phorbol myristate acetate on human neutrophil cell membrane using 31D8 monoclonal antibody. 154 11

Two superoxide dismutase-mimetic lipophilic copper complexes, Cu(II)2(indomethacin)4 [Cu(II)2(indo)4] and Cu(II)2(3,5-diisopropylsalicylate)4 [Cu(II)2(3,5-DIPS)4], were tested for their effects on the respiratory burst of intact human granulocytes and on xanthine oxidase, under conditions where superoxide and hydrogen peroxide were generated. The effect of the copper complexes on these enzyme systems (as opposed to their dismutase effect on superoxide) was determined by measuring oxygen uptake with an oxygen meter. It was found that, after a short delay, both systems were inhibited markedly by micromolar amounts of these complexes. This inhibition was prevented by treatment with EDTA or catalase if added prior to starting the reaction. Similar inhibitory effects were seen using copper sulfate. It appears that these lipophilic SOD-mimetic compounds can, in the presence of H2O2 and O2-, give rise to a species that can inhibit some component of the respiratory burst oxidase or protein kinase C in intact granulocytes and xanthine oxidase in solution. The observed decrease in O2- levels observed upon addition of these compounds is likely due to inhibition of the source and not to their SOD-mimetic properties.
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PMID:Inhibition by superoxide dismutase-mimetic copper complexes of phorbol ester-induced respiratory burst in human granulocytes. 155 79

Phorbol dibutyrate induced a nitroblue tetrazolium-reducing reaction in differentiated HL-60 cells, which was inhibited by protein kinase inhibitors such as staurosporine and H-7. ID50 of staurosporine and H-7 were 1.4 ng/ml and 0.19 mM, respectively. When tautomycin, an inhibitor of protein phosphatases, was added with the kinase inhibitors, the nitroblue tetrazolium-reducing reaction again appeared. ID50 of staurosporine was 510 ng/ml in the presence of tautomycin. Tautomycin itself weakly induced the reaction, which was inhibited by kinase inhibitors. Such a competitive effect between tautomycin and staurosporine was not observed in a cell-free system of protein kinase C. Okadaic acid had the same effect as tautomycin. The similar results were obtained when respiratory burst was quantitated by measuring H2O2 produced by canine peripheral neutrophils. The mechanism of competitive effect of tautomycin and staurosporine on respiratory burst is discussed.
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PMID:Respiratory burst induced by phorbol ester in the presence of tautomycin, a novel inhibitor of protein phosphatases. 155 17

To study the effect of the inflammatory mediator hydrogen peroxide (H2O2) on airway ciliary activity, we measured ciliary beat frequency (CBF) in cultured tracheal explants from sheep. Addition of H2O2 (10(-8) to 10(-4) M) produced a concentration-dependent mean (+/- SEM) decrease in CBF between 11.1 +/- 0.4% (P less than 0.01) and 100 +/- 0% (P less than 0.001); at each concentration, the maximal effect was reached by 20 to 25 min. Between 10(-8) and 10(-6) M H2O2, the decrease in CBF was reversible, lactate dehydrogenase (LDH) release was not significantly increased, and major morphologic lesions were not seen. At higher concentrations of H2O2, incomplete recovery of CBF (10(-5) M) or irreversible ciliostasis (10(-4) M) developed, and a significant increase in LDH and morphologic lesions were present. Catalase (2,000 U/ml) and H-7 (10(-5) M), a protein kinase inhibitor, abolished cilioinhibition produced by H2O2 at 10(-6) M and lower concentrations but not at 10(-5) M and higher concentrations. Phorbol 12-myristate 13-acetate (PMA), a protein kinase C activator, caused a dose-dependent (10(-11) to 10(-5) M), reversible decrease in CBF; this effect was abolished by H-7. We suggest that at nonlethal concentrations, H2O2 inhibits the beat frequency of airway epithelial cilia reversibly, through the activation of second messengers, including protein kinase C. This mechanism might contribute to the previously demonstrated impairment of mucociliary clearance in airway inflammation.
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PMID:Mechanism of hydrogen peroxide-induced inhibition of sheep airway cilia. 159 Oct 15

Regulatory and stimulatory mechanisms of H2O2 release from guinea pig tracheal epithelial cells were investigated. Cells in primary culture maintained in a previously described air-liquid interface system released H2O2 to the extracellular space only from the apical side of the cells. The rate of release was 0.044 +/- 0.003 nmol.min-1.mg protein-1. H2O2 release could be stimulated significantly during a 30-min incubation period with phorbol myristate acetate (PMA) and platelet-activating factor (PAF). A stimulatory effect of PAF was achieved at concentrations greater than 100 nM and with PMA at concentrations greater than 10 ng (16 nM). When protein kinase C was inactivated with staurosporine, the responses to both PAF and PMA were abolished, whereas the cyclooxygenase inhibitor, indomethacin, did not affect H2O2 generation. When guinea pig tracheal epithelial cells were exposed to sublethal concentrations of extracellular H2O2 (30 microM), H2O2 was detoxified from both apical and basal sides, H2O2 removal being significantly more rapid from the apical side of the cells. These results suggest that tracheal epithelial cells can be stimulated to generate reactive oxygen species into the airway lumen and that this occurs in response to inflammatory mediators that act through protein kinase C. Luminal H2O2 release may have developed as a defense mechanism against microbes, and, similarly, luminal detoxification of H2O2 could represent an important mechanism of modulation of airway inflammation in response to oxidant stress.
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PMID:Release of reactive oxygen species by guinea pig tracheal epithelial cells in vitro. 161 55

In binding competition assays using a protein kinase C preparation from mouse brain (particulate fraction) 3H-labelled 12-O-tetradecanoylphorbol-13-acetate (TPA), for a series of new diterpene esters (DTE) the relative binding affinity [rba = Kia(TPA)/Kia(DTE)] in relation to TPA was determined. A wide range of values was noticed, some of the DTE binding more strongly than TPA (rba greater than 1), others binding less strongly than TPA (rba less than 1) In comparative terms, competition for specific binding sites appears to correlate better with irritant than with promoting activity of the DTE. Using mouse peritoneal neutrophils, binding of [3H]-TPA was determined by a modification of the "cold-acetone filter assay"; saturation of high-affinity sites (Kda = 0.2 nM) was obtained at concentrations less than or equal to 1 nM, but there was also evidence for specific binding at "low-affinity" sites (Kda = 26 nM). Induction of chemoluminescence in the presence of luminol in mouse peritoneal neutrophils with a set of DTE usually elecited two peaks; at concentrations greater than or equal to 10 nM DTE a short-lived, "spike-like" response lasting only from 0 to about 5 min (phase A) its followed by a "plateau" response from about 5-120 min (phase B). This latter phase of chemoluminescence stimulation with luminol correlated well with the irritant potential of the DTE used. The sequence of the two phases can be inverted partially by using first TPA at 2,5 nM followed by a quick concentration increase to 100 nM; this indicates two different concentration-dependent events. As regards the intensity of the chemoluminescent response, quantitative but not qualitative differences between DTE were observed, which show some correlation with strong and weak tumour-promoting activity. Inhibition studies suggest the involvement of the myeloperoxidase/H2O2/Cl- system in the luminogenic response; it is suggested that the release of hypochlorite or a closely related oxidant may be instrumental in tumour promotion.
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PMID:Toxicodynamics of tumour promoters of mouse skin. II. Binding to protein kinase C of some new diterpene esters and induction of luminol-enhanced chemoluminescence in mouse peritoneal neutrophils. 165 79

The oxidant mitogen/tumor promoter, periodate, was used to selectively modify either the regulatory domain or the catalytic domain of protein kinase C (PKC) to induce oxidative activation or inactivation of PKC, respectively. Periodate, at micromolar concentrations, modified the regulatory domain of PKC as determined by the loss of ability to stimulate kinase activity by Ca2+/phospholipid, and also by the loss of phorbol ester binding. This modification resulted in an increase in Ca2+/phospholipid-independent kinase activity (oxidative activation). However, at higher concentrations (greater than 100 microM) periodate also modified the catalytic domain, resulting in complete inactivation of PKC. The oxidative modification induced by low periodate concentrations (less than 0.5 mM) was completely reversed by a brief treatment with 2 mM dithiothreitol. In this aspect, the modification induced by periodate was different from that of the previously reported irreversible modification of PKC induced by H2O2. However, the inactivation of PKC induced by periodate at concentrations greater than 1 mM was not reversed by dithiothreitol. Among the phospholipids and ligands of the regulatory domain tested, only phosphatidylserine protected the regulatory domain from oxidative modification. In the presence of phosphatidylserine, the catalytic site was selectively modified by periodate, resulting in formation of a form of PKC that exhibited phorbol ester binding but not kinase activity. Both reversible and irreversible oxidative activation and inactivation of PKC also were observed in intact cells treated with periodate. Taken together these results suggest that periodate, by virtue of having a tetrahedral structure, binds to the phosphate-binding regions present within the phosphatidylserine-binding site of the regulatory domain and the ATP-binding site of the catalytic domain, and modifies the vicinal thiols present within these sites. This results in the formation of intramolecular disulfide bridge(s) within the regulatory domain or catalytic domain leading to either reversible activation or inactivation of PKC, respectively. Thus, oxidant mitogen/tumor promoters such as periodate may be able to bypass normal transmembrane signalling systems to directly activate pathways involved in cellular regulation.
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PMID:Reversible oxidative activation and inactivation of protein kinase C by the mitogen/tumor promoter periodate. 165 74

Oxidative stress plays an important role in various types of cell injury and tumor promotion. Cells respond to oxidative stress in many ways including changes in membrane organization, ion movements, and altered gene expression, all of which contribute to the subsequent fate of affected cells. In this study, we investigated the expression of the proto-oncogenes c-fos, c-myc, and c-jun, which play a key role in proliferation and differentiation, using primary cultures of rat proximal tubular epithelium exposed to oxidative stress generated by the xanthine/xanthine oxidase system. This system generates superoxide and H2O2 in the extracellular space stimulating the release of active oxygen species from inflammatory cells. c-fos mRNA was expressed within 15 min, peaked at 30 min, and returned to constitutive levels by 3 h. c-jun mRNA began to rise after 30 min, peaked at 120 min, and remained above the constitutive levels up to 180 min. c-myc mRNA expression was less affected by the treatment, with levels increasing gradually over the 180 min period. The expression of c-fos was inhibited by superoxide dismutase but not by catalase and was super-induced by cycloheximide. H2O2 alone did not induce any c-fos mRNA in this system. Chelation of extracellular ionized calcium by EGTA or of intracellular ionized calcium by Quin 2/AM resulted in a marked decrease of c-fos expression. Two protein kinase C inhibitors, H-7 and staurosporine, partly diminished the expression of c-fos, whereas a third, 2-aminopurine, which has a broader spectrum of inhibiting protein kinases, almost completely abolished it. A poly ADP-ribosylation inhibitor, 3-aminobenzamide, had no effect on c-fos expression in this system. Our results show that oxidative stress provokes sequential expression of c-fos, c-jun, and c-myc, mRNA in this order. This c-fos expression appears to be largely controlled by calcium ion movement, which could include protein kinase C activation. Another protein kinase or kinases also appear to play an important role.
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PMID:Role of [Ca2+]i in induction of c-fos, c-jun, and c-myc mRNA in rat PTE after oxidative stress. 174 Feb 41

H2O2, like other oxidants, is known to act as a mitogen at low concentrations in resting Balb/3T3 or mouse epidermal JB6 cells. We described previously that H2O2 induces some early response genes in Balb/3T3 cells. We extended these observations using another cell line, MC3T3 (mouse osteoblastic) cells by examination of transcriptional activity of these genes and by using inhibitors of protein kinases. H2O2 increased the expressions of c-fos, c-jun, egr-1 and JE genes which are known to be early response genes and are induced by mitogenic stimuli in many types of cells. Exogenous addition of H2O2 increased the mRNA levels of these genes, the kinetics of increase being similar to those of their inductions by a phorbol ester or serum. Nuclear run-on transcription showed that this induction occurred at the transcriptional level. H2O2 at 0.1-0.2 mM induced maximal expressions of c-fos and c-jun, whereas 0.3 mM H2O2 was required for induction of stress-induced heme oxygenase mRNA. The inductions of c-fos and c-jun were inhibited by 50 microM H7, a protein kinase inhibitor that is relatively specific for protein kinase C, but were not affected by H9, relatively specific for cAMP-dependent protein kinase. In cells pretreated with 12-O-tetradecanoylphorbol 13-acetate, however, in which protein kinase was supposed to be downregulated, H2O2 induced c-fos and heme oxygenase as efficiently as in untreated cells. H2O2 did not increase the phosphorylation of p80 protein, which is known to be a substrate for protein kinase C. Thus, H2O2 seemed to induce c-fos and c-jun by activating protein kinases distinct from protein kinase C. Activity of the chloramphenicol acetyltransferase gene under control of the serum-response element of human c-fos genes was increased by H2O2 treatment, whereas that under control of cAMP-response element was not affected. These results indicate that the inductions by H2O2 of c-fos and possibly other early response genes are mediated through activation of the serum-response element in their enhancer.
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PMID:Transcriptional activation of early-response genes by hydrogen peroxide in a mouse osteoblastic cell line. 191 80

Carbachol, through a muscarinic receptor, thyrotropin-releasing hormone (TRH), prostaglandin F2 alpha (PGF2 alpha), bradykinin, and adenosine triphosphate (ATP) increased the apparent [Ca2+]i (intracellular free Ca2(+)-concentration) of dog thyrocytes in primary culture. The [Ca2+]i measured by the Quin-2 technique rose immediately after the addition of the agonists and reached a maximal value after less than 30 seconds. Afterwards, the [Ca2+]i declined to a plateau higher than the basal level when the cells were triggered with carbachol. By contrast, in most experiments with PGF2 alpha and in the case of bradykinin, TRH, and ATP, the [Ca2+]i returned to the basal value. If the extracellular Ca2+ was chelated by excess of EGTA, the addition of all agents caused a sharp reduced transient rise in the [Ca2+]i followed by a decline of the [Ca2+]i often below the basal level (especially in the case of carbachol). It is suggested that the first transient phase of these responses is due at least in part to the mobilisation of Ca2+ from intracellular stores whereas the second sustained phase of the response to carbachol mainly originates from an increased Ca2+ influx into the thyrocytes. Carbachol, bradykinin, TRH, PGF2 alpha, and ATP also increased generation of inositol phosphates in dog thyrocytes. This effect was sustained when the cells were triggered with carbachol and was more transient with bradykinin, TRH, PGF2 alpha, or ATP. All these agents and the phorbdester TPA as well as forskolin enhanced to various extent the thyrocyte H2O2 generation. This enhancement was severely reduced in the absence of extracellular Ca2+ and was mimicked by Ca2+ ionophores in the presence of extracellular Ca2+ especially in synergy with protein kinase C activators. These data suggest that the dog thyrocyte H2O2 generation, the limiting step of the thyroid hormone synthesis, is modulated by carbachol, TRH, PGF2 alpha, bradykinin, and ATP through their action on the Ca2(+)-phosphatidylinositol cascade.
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PMID:Control of the intracellular Ca(2+)-concentration and the inositol phosphate accumulation in dog thyrocyte primary culture: evidence for different kinetics of Ca(2+)-phosphatidylinositol cascade activation and for involvement in the regulation of H2O2 production. 199 73


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