Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:1.6.3.1 (NADPH oxidase)
11,281 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Propranolol, a beta-adrenergic receptor antagonist, also inhibits phosphatidate phosphohydrolase, the enzyme that converts phosphatidic acid into diacylglycerol. This latter effect has prompted recent use of propranolol in studies examining the importance of diacylglycerol and phosphatidic acid in cellular signalling events. Here, we show that propranolol is also an inhibitor of protein kinase C. At concentrations greater than or equal to 20 microM, propranolol reduced [3H]phorbol dibutyrate binding (IC50 = 200 microM) and phorbol myristate acetate-stimulated superoxide anion release (IC50 = 130 microM) in human neutrophils. Scatchard analysis showed that propranolol lowers the number of phorbol diester binding sites without significantly affecting their affinity. In vitro kinetic analysis, performed in a mixed micellar assay with protein kinase C purified from human neutrophils, suggested a competitive inhibition of propranolol with the cofactor phosphatidylserine. Complex kinetic patterns were observed with respect to diacylglycerol and ATP, approximating competitive and noncompetitive inhibition, respectively. Taken together, these results suggest that the drug interacts at the level of the regulatory domain of the enzyme. Fifty % inhibition occurred at approximately 150 microM propranolol. Similar levels of inhibition were obtained using exogenous (histone) and endogenous (p47-phox, a NADPH oxidase component) substrates. Protein kinase C-alpha and protein kinase C-beta, two protein kinase C isozymes present in human neutrophils, were inhibited by propranolol in a comparable manner. In the range of concentrations tested (30-1000 microM), neither cAMP-dependent protein kinase nor neutrophil protein tyrosine kinases were affected. The racemic form of propranolol and the (+) and the (-) stereoisomers were equally active, and other beta-adrenergic receptor antagonists (pindolol) and agonists (isoproterenol) were inactive. This suggests that the inhibitory action of propranolol on protein kinase C is related to the amphipathic nature of the drug rather than to its beta-adrenergic receptor blocking ability. Analogs of propranolol were synthesized and found to be more potent protein kinase C inhibitors, with IC50 values in the 10-20 microM range. We conclude that the ability of propranolol to inhibit both protein kinase C and PA phosphohydrolase complicates interpretation of results when this drug is used in signal transduction studies. In addition, propranolol may be a useful prototype for the synthesis of new protein kinase C inhibitors.
...
PMID:Propranolol, a phosphatidate phosphohydrolase inhibitor, also inhibits protein kinase C. 132

Protein kinase C (PKC) appears to have a central role in the O2- response of neutrophils following stimulation of membrane receptors. The second messenger, diacylglycerol (DG), that activates PKC is derived from membrane phospholipids via activation of phosphatidylinositol 4,5-bisphosphate (PIP2)-phospholipase C (PLC) and phospholipase D (PLD), with the latter pathway being more prominent in primed cells. In resting cells receptor coupling to PLD is through a G-protein. Priming brings a cytoplasmic tyrosine kinase into the transducer sequence which, through protein phosphorylation, increases the efficiency of coupling between membrane receptors and PLD. Phosphatidic acid (PA), the initial product of the PLD pathway, also appears to act as a second messenger by directly activating the NADPH oxidase responsible for generating O2-. Interconversion of PA and DG by phosphatidate phosphohydrolase and DG kinase determines which of these second messengers has the dominant role.
...
PMID:New pathways of phagocyte activation: the coupling of receptor-linked phospholipase D and the role of tyrosine kinase in primed neutrophils. 133 78

Conditions for superoxide anion (O2-) production were examined in guinea pig polymorphonuclear leukocytes (PMNL). When PMNL were suspended in the hypotonic medium, O2- production was significantly enhanced by concurrent treatment with low concentrations of 1-oleoyl-2-acetylglycerol (OAG), a cell-permeable protein kinase C activator. Such hypotonicity or OAG alone had little effect on the production. Other protein kinase C activators also markedly enhanced O2- production in combination with hypotonicity, but not in the isotonic medium. Protein kinase C inhibitors, H-7 and staurosporine, dose-dependently inhibited the production. These observations indicate that protein kinase C participates in such synergistic O2- production with hypotonicity. Phosphorylation of 46-kDa protein(s), which was commonly enhanced in paralleled with an activation of NADPH oxidase in guinea pig PMNL, was increased by treatment with 10 microM OAG, but the phosphorylation was little altered by hypotonic treatment. Intracellular calcium concentration, arachidonate release, and 1,2-diacylglycerol and phosphoinositide concentrations were slightly altered by hypotonic treatment. A change in phosphatidate (PA) production in PMNL was induced by hypotonic treatment either by itself or in combination with OAG treatment. These results suggest that the combination of cell membrane changes by hypotonic treatment accompanied by the increase in PA and 46-kDa protein phosphorylation by protein kinase C provides the conditions required for a marked increase in O2- production. Hypotonicity may be a good tool for studying the mechanism of priming in the activation of NADPH oxidase.
...
PMID:Stimulation of superoxide anion production in guinea pig polymorphonuclear leukocytes by hypotonic conditions in combination with protein kinase C activators. 165 87

The effects of lidocaine, a local anesthetic, on various stimulation-coupled responses of neutrophils were studied. Superoxide generation, generation of chemiluminescence, depolarization of membrane potential and transitional increase in intracellular Ca2+ were inhibited by lidocaine in a concentration dependent manner. Lidocaine also inhibited Ca(2+)-activated phospholipid-dependent protein kinase (PKC) in the presence of various concentrations of Ca2+, phosphatidylserine and dioleoylglycerol. For the inhibition of all these stimulation-coupled responses, a similar order of the lidocaine concentration was needed. As in the case of dibucaine (Mori, T., Takai, Y., Minakuchi, R., Yu, B. and Nishizuka, Y., J. Biol. Chem. 255:8378-8380, 1980), lidocaine inhibited PKC activity in a manner competitive with phosphatidylserine. Lidocaine also inhibited the phosphorylation of 47 kDa neutrophil cytosplasmic protein, a phosphorylated protein required for NADPH oxidase activation. Thus, the cellular membrane phospholipid may be one of the target sites of lidocaine for the inhibitory action on the various stimulation-coupled responses of neutrophils, and these effects of lidocaine may correlate with its inhibitory action on PKC activity.
...
PMID:Lidocaine inhibits stimulation-coupled responses of neutrophils and protein kinase C activity. 196 97

Effect of biscoclaurine alkaloids, such as cepharanthine, on active oxygen production of neutrophils was investigated. Cepharanthine inhibited both superoxide generation and luminol-dependent chemiluminescence (CL) induced by either formylmethionyl-leucyl-phenylalanine, opsonized zymosan, arachidonic acid or by phorbol myristate acetate. Ca2(+)- and phospholipid-dependent protein kinase (PKC) activity and the phosphorylation of cytoplasmic protein including 47 kDa proteins of neutrophils were also inhibited by cepharanthine; dose dependent inhibition of CL was quite similar to that of PKC. Among various biscoclaurines tested, the inhibitory effect of cepharanthine, tetrandrine and isotetrandrine was strong, but that of berbamine and cycreanine was weak; the inhibitory action of the former on lipid peroxidation and platelet aggregation were also stronger than those of the latter. These and other observations indicated that these alkaloids inhibited the active oxygen generation by way of stabilizing plasma membrane and inhibiting PKC and NADPH oxidase activation.
...
PMID:Inhibition of active oxygen generation in guinea-pig neutrophils by biscoclaurine alkaloids. 215 45

Evidences have been provided in our laboratory that in neutrophils different signal transduction sequences for the activation of O2(-)-forming NADPH oxidase can be triggered by the same stimulus (Biochem. Biophys. Res. Commun. 1986, 135, 556-565; 1986, 135, 785-794; 1986, 140, 1-11). The results presented here show that the transduction sequence triggered by fluoride via dissociation of G-proteins and involving messengers produced by stimulation of phosphoinositide turnover, Ca2+ changes and translocation of protein kinase C from the cytosol to the plasmamembrane, can be bypassed when a primed state of neutrophils is previously induced. In fact: i) fluoride causes a pertussis toxin insensitive and H-7 sensitive respiratory burst in human neutrophils, which is linked to the activation of hydrolysis of PIP2, rise in [Ca2+]1 and translocation of PKC. In Ca2+-depleted neutrophils these responses to fluoride do not occur and are restored by addition of CaCl2. ii) The pretreatment of Ca2+-depleted unresponsive neutrophils with non stimulatory doses of PMA restores the activation of the NADPH oxidase by fluoride but not the turnover of phosphoinositides and PKC translocation. The nature of the alternative transduction sequence, the reactions different from phospholipase C activated by G-protein for the alternative sequence and the role of these discrete pathways for NADPH oxidase activation are discussed.
...
PMID:Fluoride can activate the respiratory burst independently of Ca2+, stimulation of phosphoinositide turnover and protein kinase C translocation in primed human neutrophils. 282 1

Protein kinase C may be important in leukocyte function, because it is activated by phorbol myristate acetate (PMA), a potent stimulus of the respiratory burst in neutrophils. The localization of protein kinase C was compared in unstimulated and PMA-stimulated human neutrophils. Protein kinase C was primarily cytosolic in unstimulated cells but became associated with the particulate fraction after treatment of cells with PMA. The particulate-associated kinase activity did not require added calcium and lipids, but when extracted by Triton X-100 (greater than or equal to 0.2%), calcium and phospholipid dependence could be demonstrated. The EC50 of PMA for stimulating kinase redistribution and activation of NADPH oxidase, the respiratory burst enzyme, were similar (30 to 40 nM). Redistribution of protein kinase C occurred rapidly (no lag) and preceded NADPH oxidase activation (30 sec lag). These results suggest that redistribution of protein kinase C is linked to activation of the respiratory burst in human neutrophils.
...
PMID:Phorbol myristate acetate mediates redistribution of protein kinase C in human neutrophils: potential role in the activation of the respiratory burst enzyme. 316 Jul 85

The mechanisms regulating activation of the respiratory burst enzyme, NADPH oxidase, of human neutrophils (PMN) are not yet understood, but protein phosphorylation may play a role. We have utilized a defect in a cytosolic factor required for NADPH oxidase activation observed in two patients with the autosomal recessive form of chronic granulomatous disease (CGD) to examine the role of protein phosphorylation in activation of NADPH oxidase in a cell-free system. NADPH oxidase could be activated by SDS in reconstitution mixtures of cytosolic and membrane subcellular fractions from normal PMN, and SDS also enhanced phosphorylation of at least 16 cytosolic and 14 membrane-associated proteins. However, subcellular fractions from CGD PMN plus SDS expressed little NADPH oxidase activity, and phosphorylation of a 48-kD protein(s) was selectively defective. The membrane fraction from CGD cells could be activated for NADPH oxidase when mixed with normal cytosol and phosphorylation of the 48-kD protein(s) was restored. In contrast, the membrane fraction from normal cells expressed almost no NADPH oxidase activity when mixed with CGD cytosol, and phosphorylation of the 48-kD protein(s) was again markedly decreased. Protein kinase C (PKC) activity in PMN from the two patients appeared to be normal, suggesting that a deficiency of PKC is not the cause of the defective 48-kD protein phosphorylation and that the cytosolic factor is not PKC. These results demonstrate that the cytosolic factor required for activation of NADPH oxidase also regulates phosphorylation of a specific protein, or family of proteins, at 48 kD. Although the nature of this protein(s) is still unknown, it may be related to the functional and phosphorylation defects present in CGD PMN and to the activation of NADPH oxidase in the cell-free system.
...
PMID:Coregulation of NADPH oxidase activation and phosphorylation of a 48-kD protein(s) by a cytosolic factor defective in autosomal recessive chronic granulomatous disease. 336 3

Formyl-methionyl-leucyl-phenylalanine (fMLP) and 1-oleoyl-2-acetyl-glycerol (OAG) are synergistic stimuli of the respiratory burst of neutrophils. Simultaneous exposure to both agents greatly enhanced superoxide production, both in rate and extent. OAG potentiated the response to fMLP also in Ca++ -free medium. Pretreatment of the neutrophils with fMLP drastically shortened the lag of superoxide production in response to OAG. Our findings lead to the following conclusions: (i) Protein kinase C is likely to be involved in the activation of the NADPH oxidase by fMLP; (ii) OAG appears to be utilized as an intermediate in the activation process; (iii) prestimulation of the cells with fMLP facilitates the response to OAG.
...
PMID:Activation of NADPH oxidase of human neutrophils. Potentiation of chemotactic peptide by a diacylglycerol. 609 43

Phorbol ester (TPA) is generally considered to be a negative regulator of PtdIns-PLC activity. Here we show, for the first time, that the combination of TPA+ vanadate is a positive regulator (activator) of PtdIns-PLC in mouse elicited peritoneal macrophages. Vanadate or TPA on their own had no effect on PtdIns-PLC activity. In addition, TPA+ vanadate enhanced reactive oxygen species formation and protein tyrosine phosphorylation. PtdIns-PLC activation was suppressed by down regulation or inhibition of PKC, by inhibition of NADPH oxidase activity and scavenging of its product, and by inhibitors of protein tyrosine kinase activity. We conclude that PKC activation by TPA in the presence of vanadate activates the formation of reactive oxygen species, which are essential for the enhancement of protein tyrosine phosphorylation and eventually to PtdIns-PLC activation.
...
PMID:Activation of macrophage PtdIns-PLC by phorbol ester and vanadate: involvement of reactive oxygen species and tyrosine phosphorylation. 751 Jan 6


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

---