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:2.7.11.1 (protein kinase)
81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We recently reported a novel intracellular mechanism of renal Na-K-ATPase regulation by agents that increase cell cAMP, which involves protein kinase A-phospholipase A2 and is mediated by one or more arachidonic acid metabolites (Satoh, T., H. T. Cohen, and A. I. Katz. 1992. J. Clin. Invest. 89:1496). The present studies were, therefore, designed to assess the role of eicosanoids in the modulation of Na-K-ATPase activity in the rat cortical collecting duct. The effect of various cAMP agonists (dopamine, fenoldopam, vasopressin, forskolin, and dibutyryl cAMP), which inhibited the pump to a similar extent (approximately 50%), was independent of altered Na entry as it was elicited in the presence of amiloride or nystatin, or when NaCl was replaced with choline Cl. This effect was completely blocked by SKF 525A or ethoxyresorufin, two inhibitors of the cytochrome P450-dependent monooxygenase pathway, or by pretreating the animals with CoCl2, which depletes cytochrome P450. Equimolar concentrations (10(-7) M) of the cyclooxygenase inhibitors indomethacin or meclofenamate caused only a partial inhibition of the cAMP agonists' effect on the pump, whereas nordihydroguaiaretic acid or A 63162, two inhibitors of the lipoxygenase pathway, were without effect. Furthermore, two products of this pathway, leukotriene B4 and leukotriene D4, had no effect on Na-K-ATPase activity, and ICI 198615, a leukotriene receptor antagonist, did not alter pump inhibition by cAMP agonists. Several P450 monoxygenase arachidonic acid metabolites (5,6-epoxyeicosatrienoic acid; 11,12-epoxyeicosatrienoic acid; 11,12-dihydroxyeicosatrienoic acid; and 12(R)-hydroxyeicosatetraenoic acid) as well as PGE2 inhibited the Na:K pump in dose-dependent manner, but the effect of PGE2 was blocked when Na availability was altered, whereas that of 12(R)-HETE remained unchanged. We conclude that the cytochrome P450-monooxygenase pathway of the arachidonic acid cascade plays a major role in the modulation of Na:K pump activity by eicosanoids in the rat cortical collecting duct, and that products of the cyclooxygenase pathway may contribute to pump inhibition indirectly, by decreasing intracellular Na.
...
PMID:Intracellular signaling in the regulation of renal Na-K-ATPase. II. Role of eicosanoids. 838 20

Arachidonic acid (AA) stimulated protein phosphorylation in electrically permeabilised islets, most notably of an islet protein of approximate molecular weight 18 kDa. This protein did not appear to be a substrate for cAMP-dependent protein kinase. The AA-induced protein phosphorylation was mediated by unmetabolised AA since the lipoxygenase inhibitor, nordihydroguaretic acid (NDGA), or the cyclooxygenase inhibitor, indomethacin, did not significantly reduce AA-induced phosphorylation. Although saturated fatty acids did not stimulate phosphorylation of islet proteins, a number of cis-unsaturated fatty acids, other than AA, induced 32P incorporation into an 18 kDa protein. However, some fatty acids which stimulated protein phosphorylation had no effect on insulin secretion in experiments where AA clearly stimulated insulin secretion. AA stimulated protein kinase C (PKC) activity extracted from islets but several fatty acids which induced protein phosphorylation had no significant effect on PKC activity in vitro. 50 nM staurosporine had no effect on AA-induced protein phosphorylation but this concentration of staurosporine markedly inhibited PKC activity. 200 nM staurosporine caused complete inhibition of the AA-induced phosphorylation without having any effect on AA-induced insulin secretion. These results suggest that AA and some other fatty acids can promote 32P incorporation into islet proteins, independently of PKC activation, and that AA-induced phosphorylation is not required for insulin secretory responses to AA.
...
PMID:Arachidonic acid-induced insulin secretion from rat islets of Langerhans is not mediated by protein phosphorylation. 838 12

The abilities of platelet-derived growth factor (PDGF) and insulin-like growth factor (IGF-I) to regulate cAMP metabolism and mitogen-activated protein kinase (MAP kinase) activity were compared in human arterial smooth muscle cells (hSMC). PDGF-BB stimulated cAMP accumulation up to 150-fold in a concentration-dependent manner (EC50 approximately 0.7 nM). The peak of cAMP formation and cAMP-dependent protein kinase (PKA) activity occurred approximately 5 min after the addition of PDGF and rapidly declined thereafter. Incubating cells with PDGF and 3-isobutyl-1-methylxanthine (IBMX, a phosphodiesterase inhibitor) enhanced the accumulation of cAMP and PKA activity by an additional 2.5-3-fold, whereas IBMX alone was essentially without effect. The PDGF-stimulated increase in cAMP was prevented by addition of the cyclooxygenase inhibitor indomethacin, consistent with release of prostaglandins stimulating cAMP. PDGF, but not IGF-I, stimulated MAPK activity, cytosolic phospholipase A2 (cPLA2) phosphorylation, and cAMP synthesis which indicated a key role for MAP kinase in the activation of cPLA2. Further, PDGF stimulated the rapid release of arachidonic acid and synthesis of prostaglandin E2 (PGE2) which could be inhibited by a cPLA2 inhibitor (AACOCF3). Calcium mobilization was required for PDGF-induced arachidonic acid release and PGE2 synthesis but not for MAPK activation, whereas PKC was required for PGE2-mediated activation of PKA. In summary, these results demonstrated that PDGF increases cAMP formation and PKA activity through a MAP kinase-mediated activation of cPLA2, arachidonic acid release, and PGE2 synthesis in human arterial smooth muscle cells.
...
PMID:Platelet-derived growth factor stimulates protein kinase A through a mitogen-activated protein kinase-dependent pathway in human arterial smooth muscle cells. 855 Jun 11

Nimesulide (CAS 51803-78-2) has been shown to exert a marked anti-inflammatory effect in several in vivo models of inflammation. Recent studies indicate that nimesulide not only inhibits prostaglandin synthesis in certain cell types, but also has pleiotropic effects on neutrophil functions, including the respiratory burst, integrin-mediated adherence and synthesis of platelet-activating factor (PAF). In the present study, the effect of nimesulide on PAF synthesis was compared with its effect on the production of leukotriene B4 (LTB4). Nimesulide dose-dependently inhibited both processes in neutrophils stimulated by serum-treated zymosan (STZ) with a comparable efficacy (IC50 values between 10 and 20 mumol/l). In formyl-methionyl-leucyl-phenylalanine-stimulated neutrophils (treated with cytochalasin B), these IC50 values were 30 and 50 mumol/l for PAF and LTB4 synthesis, respectively. These results indicate an inhibition by nimesulide of a common step in the release of these lipid mediators, i.e. the activation of phospholipase A2, possibly by elevating intracellular cAMP. In support of this latter hypothesis, it was observed that nimesulide increased the level of cAMP almost 3-fold after STZ stimulation, whereas in fMLP-stimulated neutrophils these changes in cAMP levels were more dramatic. Furthermore, the inhibitory effects of nimesulide on PAF and LTB4 production could largely be prevented by addition of H89, an inhibitor of cAMP-dependent protein kinase (PK-A). It is concluded that an increase in intracellular cAMP is instrumental in the observed effects of nimesulide on the release of PAF and LTB4 by activated neutrophils and that limited availability of arachidonic acid, also the substrate for the cyclooxygenase pathway, may very well contribute to the effects of nimesulide on prostaglandin synthesis observed in other cell types.
...
PMID:Inhibition of the production of platelet activating factor and of leukotriene B4 in activated neutrophils by nimesulide due to an elevation of intracellular cyclic adenosine monophosphate. 859 70

To examine the mechanisms by which endothelin (ET) regulates the Na/H antiporter isoform, NHE-3, OKP cells were stably transfected with ET(A) and ET(B) receptor cDNA. In cells overexpressing ET(B), but not ET(A) receptors, ET-1 increased Na/H antiporter activity (JNa/H). This effect was inhibited by a nonselective endothelin receptor blocker and by a selective ET(B) receptor blocker but was not inhibited by an ET(A) selective receptor blocker. In ET(B)-overexpressing cells, 10(-8) M ET-1 inhibited adenylyl cyclase, but protein kinase A inhibition and pertussis toxin pretreatment did not affect Na/H antiporter activation by ET-1. ET-1 caused a transient increase in cell [Ca2+], followed by a sustained increase. Increases in cell [Ca2+] were partially inhibited by pertussis toxin. ET-1-induced increases in J(Na/H) were 50% inhibited by clamping cell [Ca2+] low with BAPTA, and by KN62, a Ca-calmodulin kinase inhibitor. Inhibitors of protein kinase C, cyclooxygenase, lipoxygenase, and cytochrome P450 and cyclic GMP were without effect. In ET(A)-overexpressing cells, ET-1 increased cell [Ca2+] but did not increase JNa/H. In summary, binding of ET-1 to ET(B) receptors increases Na/H antiporter activity in OKP cells, an effect mediated in part by increases in cell [Ca2+] and Ca-calmodulin kinase. Increases in cell [Ca2+] are not sufficient for Na/H antiporter activation.
...
PMID:Endothelin(B) receptor activates NHE-3 by a Ca2+-dependent pathway in OKP cells. 861 78

Lipid mediators of inflammation, contribute to airway hyper-reactivity in asthma. Since production of lipid mediators is largely regulated by phospholipase A2 (PLA2), and since PLA2 expression in mesenchymal cells is induced by cytokines and other signals, we examined PLA2 expression by rat tracheobronchial smooth muscle cells (TBSMC). PLA2 expression in TBSMC cultures was markedly increased by tumour-necrosis factor (TNF) alpha (130-fold) and interleukin-1beta (IL-1beta) (7.4-fold). Lipopolysaccharide (LPS;100 ng/ml) resulted in a 51-fold increase in extracellular PLA2 activity. PLA2 expression by LPS-stimulated or cytokine-stimulated cells was downregulated by dexamethasone. Whereas forskolin or dibutyrl cAMP increased PLA2 activity, inhibition of protein kinase A but not tyrosine kinase reduced PLA2 expression. Northern blot analysis showed that TNF alpha and IL-1beta increased both PLA2 and inducible cyclooxygenase (Cox-2) mRNA transcription. Addition of dexamethasone substantially blunted the increase in PLA2 and Cox-2 mRNA. In contrast, the level of Cox-1 mRNA was very low and did not change with the various treatments. Since proinflammatory lipid mediators have been implicated in the pathogenesis of asthma and PLA2 activity regulates generation of these lipid mediators, cytokine-stimulated synthesis and release of PLA2 by airway smooth cells may contribute to the potentiation of airway inflammation in asthma.
...
PMID:Secretory non-pancreatic phospholipase A2 and cyclooxygenase-2 expression by tracheobronchial smooth muscle cells. 865 1

Extracellular ATP causes 40% stimulation of Mg2+ efflux from Ehrlich ascites tumor cells (EATC) incubated under 0-trans conditions. ATP also causes a threefold increase of arachidonic acid (AA) metabolite release from [3H]AA-preloaded EATC, indicating that, under these experimental conditions, it induces phospholipase A2 (PLA2) activation. ATP-induced Mg2+ efflux can be prevented by cyclooxygenase inhibition with indomethacin or lysine acetylsalicylate, but not by 5-lipooxygenase inhibition with BWA4C. Mg2+ efflux is also directly stimulated by exogenous AA in a concentration-dependent manner. This phenomenon involves PKA as it is virtually abolished by the specific inhibitor 8-bromoadenosine-3',5'-cyclic monophosphothioate. While stimulating Mg2+ efflux, exogenous AA also increases cAMP content of EATC and this effect can be prevented by cyclooxygenase inhibition. Measurements in mag-fura-2-loaded EATC reveal that stimulation of Mg2+ efflux does not correlate with significant fluctuations of [Mg2+]i. This suggests that Mg2+ efflux is compensated for by mobilization of bound Mg2+, leaving [Mg2+]i unaltered. Altogether these data indicate that Mg2+ efflux can be modulated by extracellular stimuli capable of activating PLA2. This modulation is triggered by cyclooxygenase products which, by activating adenylcyclase, determine an elevation of cAMP. This intracellular messenger upregulates Na-dependent Mg2+ efflux.
...
PMID:Regulation of intracellular magnesium in ascites cells: involvement of different regulatory pathways. 866 Jun 98

Cyclooxygenase-2 (COX-2) is an inducible cyclooxygenase enzyme and may play an important role in the pathogenesis of lung injury and in pulmonary vascular remodeling. In this study we determined the effects of acute or chronic hypoxia on COX-2 induction and its modulation by .NO and adenosine 3'-5'-cyclic monophosphate (cAMP). Isolated perfused rat lungs were exposed to a normoxic gas mixture or a hypoxic gas mixture for 3 h. Northern blot analysis showed that 3 h of acute hypoxia were sufficient to increase COX-2 but not COX-1 transcripts in the lung. COX-2 expression induced by acute hypoxia was enhanced by an inhibitor of nitric oxide synthase, N(G)-nitro-L-arginine methyl ester, and was suppressed by sodium nitroprusside, meclofenamate, and H-7 (an inhibitor of protein kinase A and C). COX-2 expression was also enhanced by dibutyryl cAMP and iloprost, a prostacyclin analogue. In contrast, 2 wk of chronic hypobaric hypoxia did not enhance COX-2 expression in the lung, but increased COX-2 protein levels, as assessed by Western blots. We conclude that acute hypoxia induces COX-2 gene expression in rat lung and that COX-2 induction by acute hypoxia is modulated by .NO, cAMP, and cyclooxygenase products. In particular, prostacyclin produced by the lung during hypoxia or shear stress induces lung COX-2 expression via a positive feedback mechanism.
...
PMID:Effects of acute and chronic hypoxia on rat lung cyclooxygenase. 896 23

Infectious microorganisms can differently induce or inhibit apoptosis of immunocompetent effector and host cells. In this study we examined the influence of an infection by Candida albicans (C. albicans) on programmed cell death of monocytic U937 cells and human monocytes. Basal and tumor necrosis factor alpha (TNF-alpha)-induced DNA fragmentation of U937 cells was significantly inhibited by an infection with C. albicans. Enhanced apoptosis of U937 cells, induced by TNF-alpha, caused a diminished candidacidal activity of the effector cells, whereas inhibition of apoptosis by granulocyte-macrophage colony-stimulating factor (GM-CSF) was paralleled by an intensified host defense. Pretreatment of U937 cells or monocytes with the cyclooxygenase blocker indomethacin completely abolished the reduction of DNA fragmentation induced by the yeast. Studying the underlying mechanisms we found that C. albicans induced formation of prostaglandin E2 (PGE2) by U937. Exogenous administration of PGE2 down-regulated apoptosis of U937 or human monocytes to a similar extent as did fungal infection. Activation of protein kinase A by the cAMP analogue 8-bromo-cAMP inhibited U937 apoptosis, as did PGE2. On the other hand, rp-cAMP, a blocker of the cAMP-dependent signal transduction, restored and elevated DNA fragmentation levels down-regulated by C. albicans. U937 cells expressed the bcl-2 protein but the infection with fungi or PGE2 treatment did not increase proto-oncogene expression. Monocytic effector cells may therefore strengthen the defense against C. albicans by an autocrine feedback regulation via a PGE2-dependent, cAMP-transduced inhibition of apoptosis.
...
PMID:Infection by Candida albicans inhibits apoptosis of human monocytes and monocytic U937 cells. 897 76

The mechanisms involved in the spasmolytic effect of a lipidic extract from Sabal serrulata fruits were investigated. The extract relaxed vanadate-induced contractions on rat uterus incubated in a calcium free solution (EC50 = 11.41 +/- 1.38 micrograms/ml). The modification of the effect by a cyclooxygenase inhibitor (indomethacin), a protein kinase A inhibitor (TPCK), calcium modifying drugs, and drugs interfering with transcription and protein synthesis has been assayed. The effect was unmodified by a 3 microM concentration of indomethacin, (EC50 = 8.77 +/- 1.28 vs 11.41 +/- 1.38 micrograms/ml) and a 5 micrograms/ml concentration of the transcription inhibitor, actinomycin D, (EC50 = 8.23 +/- 2.19 vs 11.41 +/- 1.38 micrograms/ml). The inhibitor of intracellular calcium mobilization TMB-8 (0.1 mM), the Na+/Ca+2 exchanger inhibitor amiloride (0.1 mM), the calcium chelator BAPTA-AM (50 microM), the PKA inhibitor TPCK (10 microM), and the protein synthesis inhibitor cycloheximide (10 micrograms/ml) significantly shifted to the right the dose-response curve of the extract (EC50 = 17.83 +/- 1.87 micrograms/ml, 18.61 +/- 2.50 micrograms/ml, 35.28 +/- 9.13 micrograms/ml, 33.99 +/- 3.07 micrograms/ml, and 27.31 +/- 4.93 micrograms/ml, respectively, vs 11.41 +/- 1.38 micrograms/ml). These results suggest that the effect of the lipidic extract from S. serrulata fruits could be partially due to Na+/Ca+2 exchanger activation and interference with intracellular calcium mobilization, and point to cAMP as a possible mediator. Moreover, protein synthesis seems to be involved in the spasmolytic activity.
...
PMID:Spasmolytic activity of a lipidic extract from Sabal serrulata fruits: further study of the mechanisms underlying this activity. 900 Aug 82


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

---