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

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Query: EC:3.1.4.3 (phospholipase C)
18,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of sulphasalazine on the production of second messenger compounds in human granulocytes have been characterised by various stimuli. The increases in cytosolic calcium, inositol trisphosphate, diacylglycerol, and phosphatidic acid (all important mediators of intracellular signal transduction) triggered by stimulation were inhibited by sulphasalazine. The metabolites 5-amino-salicylic acid and sulphapyridine were less potent inhibitors than the mother compound. It is concluded that sulphasalazine inhibits the synthesis of phosphoinositide derived second messenger compounds at the level of phospholipase C or its regulatory guanosine 5'-triphosphate (GTP) binding protein. Inhibition of phosphatidic acid synthesis was either due to the same mechanism, or to interaction with a phospholipase D regulating GTP binding protein.
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PMID:Sulphasalazine inhibition of human granulocyte activation by inhibition of second messenger compounds. 136 17

We have shown previously that aspirin (ASA) ingestion by normal human volunteers inhibits peripheral blood monocyte phospholipase C (PLC) activities ex vivo. In order to explore further the mechanism of action of ASA, normal human monocytes and differentiated human U937 cells were treated with ASA and other salicylates. Cells preincubated with ASA were found to have decreased PLC activities. Phospholipase A2 activities were not affected by salicylates. Sodium salicylate and salicylic acid, nonacetylated relatives of ASA also inhibited PLC activity. This effect was dose and time dependent and addition of cycloheximide or actinomycin D to the preincubation mixture abrogated the inhibitory effect of salicylates on PLC. This PLC inhibitory protein induced by ASA appears distinct from lipocortin, a phospholipase A2 inhibitory protein inducible by corticosteroids.
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PMID:Aspirin inhibits phospholipase C. 294 50

A new salicylic acid derivative, caloporoside, was isolated from fermentations of Caloporus dichrous. Its structure was elucidated by a combination of chemical and spectroscopic methods. Caloporoside exhibits weak antibacterial and antifungal activities and is a quite selective inhibitor of phospholipase C isolated from pig brain (Ki 12, 3 microM).
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PMID:Caloporoside, a new inhibitor of phospholipases C from Caloporus dichrous (Fr.) Ryv. 800 80

-The anti-inflammatory effects of salicylate are well known, but the intracellular mechanisms underlying those effects remain to be clarified and are not explained solely by an influence on cyclooxygenase activity. In the present study, we have used cardiac fibroblasts stimulated by either angiotensin II (Ang II) or platelet-derived growth factor (PDGF) to demonstrate an inhibitory effect of salicylate on the phosphorylation of the nonreceptor tyrosine kinases, proline-rich tyrosine kinase 2 (PYK2) and c-Src, by immunoprecipitation and immunoblotting methods. This inhibition was dose dependent, with a clear effect observed at concentrations between 5 and 20 mmol/L salicylate. Intracellular Ca(2+) chelation and protein kinase C (PKC) inhibition reduced Ang II and PDGF-induced PYK2 and c-Src phosphorylation. Salicylate significantly inhibited the phosphorylation of both of the tyrosine kinases activated by either ionophore A23187 or thapsigargin treatment, which led to an elevation of cytosolic Ca(2+). Activation of PKC by phorbol ester phosphorylated both PYK2 and Src, and this effect also was attenuated by salicylate. In contrast, salicylate had no effect on either the transactivation of the epidermal growth factor receptor by Ang II or the phosphorylation of phospholipase C-gamma by PDGF. These studies indicate a novel site of action for salicylate on PYK2 and c-Src phosphorylation and suggest that this inhibitory effect on these important signaling intermediates may be through a Ca(2+)- and PKC-dependent mechanism.
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PMID:Salicylate Inhibits Phosphorylation of the Nonreceptor Tyrosine Kinases, Proline-Rich Tyrosine Kinase 2 and c-Src. 1120 70

Staphylococcus aureus is a ubiquitous gram-positive bacterium that can cause superficial to serious systemic infections in animals and humans. Here we report the development of a plant infection model to study the pathogenesis of this bacterium. Three global regulatory mutants, RN6911 (agr-), ALC 488 (sarA-) ALC 842 (sarA-/agr-) and an alpha-toxin mutant defective in biofilm formation (DU1090) which are attenuated in animal pathogenesis, were also attenuated in their ability to infect plants, suggesting that these regulators that mediate synthesis of virulence factors essential for animal pathogenesis are also required for plant pathogenesis. Further, using Arabidopsis plants altered in defense responses such as the transgenic lines NahG [defective in salicylic acid (SA) accumulation], and 35S-LOX2- (defective in jasmonic acid production and hyper-accumulator of SA), and mutants ics1 (depleted in SA accumulation), and npr1-1 (non-expressor of pathogenesis-related protein) we show that resistance of Arabidopsis to typical plant pathogens and the animal pathogen S. aureus is conserved and is mediated by SA. The data presented here suggest that Arabidopsis thaliana resistance to S. aureus is mediated either by a direct effect of SA on the pathogen, specifically one that affects the attachment/aggregate formation on the root surface and reduces the pathogen's virulence, or by SA-dependent, NPR1-independent host responses.
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PMID:Staphylococcus aureus pathogenicity on Arabidopsis thaliana is mediated either by a direct effect of salicylic acid on the pathogen or by SA-dependent, NPR1-independent host responses. 1584 26

Platelet-activating factor (PAF) is a pro-inflammatory lipid mediator that increases vascular permeability by simultaneous activation of two pathways, one dependent on the cyclooxygenase metabolite prostaglandin E2 and the other on the sphingomyelinase metabolite ceramide. The hypothesis that part of the PAF-induced oedema is mediated via the inositol 1,4,5-trisphosphate (IP3) pathway or Rho kinase pathway was investigated. Oedema formation was induced in isolated perfused rat lungs by injection of 5 nmol PAF into the pulmonary artery. Lungs were pre-treated with specific inhibitors: edelfosine (L108) to block phosphatidyl-inositol-specific phospholipase C, xestospongin to block the IP3 receptor, 5-iodonaphthalene-1-sulphonyl-homopiperazine (ML-7) to block myosin light chain kinase, and (+)-R-trans-4-(aminoethyl)-N-(4-pyridyl)cyclohexanecarboxamide (Y27632) to block Rho-associated protein kinase. Pre-treatment with L108 or xestospongin reduced PAF-induced oedema formation by 58 and 56%, respectively. The effect of L108 was additive to that of the cyclooxygenase inhibitor acetyl salicylic acid (88% oedema reduction). PAF-induced oedema formation was also reduced if extracellular calcium concentrations were lowered. Furthermore, treatment with ML-7 reduced oedema formation by 54%, whereas Y27632 was without effect. It is concluded that platelet-activating-factor-triggered oedema is mediated by activation of the inositol 1,4,5-trisphosphate pathway, influx of extracellular calcium and subsequent activation of a myosin light chain kinase-dependent and Rho-associated-protein-kinase-independent mechanism.
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PMID:The inositol trisphosphate pathway mediates platelet-activating-factor-induced pulmonary oedema. 1586 42

The relationship between the accumulation in endogenous free salicylic acid (SA) induced by heat acclimation (37 degrees C) and the activity of PIP(2)-phospholipase C (PIP(2)-PLC; EC 3.1.4.3) in the plasma membrane fraction was investigated in pea (Pisum sativum L.) leaves. We focused our attention on the hypothesis that positive SA signals induced by heat acclimation may be relayed by PIP(2)-PLC. Heat acclimation induced an abrupt elevation of free SA preceding the activation of PLC toward PIP(2). Immunoblotting indicated a molecular mass with 66.5kDa PLC plays key role in the development of thermotolerance in pea leaves. In addition, some characterizations of PLC toward PIP(2) isolated from pea leaves with two-phase purification containing calcium concentration, pH and a protein concentration were also studied. Neomycin sulfate, a well-known PIP(2)-PLC inhibitor, was employed to access the involvement of PIP(2)-PLC in the acquisition of heat acclimation induced-thermotolerance. We were able to identify a PIP(2)-PLC, which was similar to a conventional PIP(2)-PLC in higher plants, from pea leaves suggesting that PIP(2)-PLC was involved in the signal pathway that leads to the acquisition of heat acclimation induced-thermotolerance. On the basis of these results, we conclude that the involvement of free SA may function as the upstream event in the stimulation of PIP(2)-PLC in response to heat acclimation treatment.
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PMID:Contributions of PIP(2)-specific-phospholipase C and free salicylic acid to heat acclimation-induced thermotolerance in pea leaves. 1645 54

Phospholipid signaling is an important component in eukaryotic signal transduction pathways. In plants, it plays a key role in growth and development as well as in responses to environmental stresses, including pathogen attack. We investigated the involvement of both phospholipase C (PLC, EC 3.1.4.11) and D (PLD, EC 3.1.4.4) in early responses to the treatment of Brassica napus plants with the chemical inducers of systemic acquired resistance (SAR): salicylic acid (SA), benzothiadiazole (BTH), and with the inducer mediating the induced systemic resistance (ISR) pathway, methyl jasmonate (MeJA). Rapid activation (within 0.5-6 h treatment) of the in vitro activity level was found for phosphatidyl inositol 4,5 bisphosphate (PIP2)-specific PLC (PI-PLC) and three enzymatically different forms of PLD: conventional PLDalpha, PIP2-dependent PLD beta/gamma, and oleate-stimulated PLDdelta. The strongest response was found in case of cytosolic PIP2-dependent PLD beta/gamma after BTH treatment. PLDdelta was identified in B. napus leaves and was very rapidly activated after MeJA treatment with the highest degree of activation compared to the other PLD isoforms. Interestingly, an increase in the amount of protein was observed only for PLDgamma and/or delta after ISR induction, but later than the activation occurred. These results show that phospholipases are involved in very early processes leading to systemic responses in plants and that they are most probably initially first activated on post translational level.
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PMID:Involvement of phospholipases C and D in early response to SAR and ISR inducers in Brassica napus plants. 1664 31

Salicylic acid (SAL) may impact Staphylococcus aureus virulence by activating the sigB operon (rsbU-V-W-sigB), thus leading to reductions in alpha-toxin production and decreased fibronectin binding (L. I. Kupferwasser et al., J. Clin. Investig. 112:222-233, 2003). As these prior studies were performed in strain RN6390 (an rsbU mutant) and its rsbU-repaired variant, SH1000, the current investigation was designed to determine if the SAL effect occurs via rsbU- and/or rsbV-dependent pathways in an rsbU-intact S. aureus strain (FDA486). We thus quantified the transcription from two sigB-dependent promoters (asp23 and sarA P3) in FDA486 in response to SAL exposure in vitro, using isogenic single-knockout constructs of rsbU, rsbV, or rsbW and a green fluorescent protein reporter system. SAL induced sarA P3 and asp23 promoter activities in a dose-dependent manner in the parental strain. In contrast, sigB activation by SAL was progressively more mitigated in the rsbU and rsbV mutants. As predicted, SAL caused significant reductions in both alpha-toxin production and fibrinogen and fibronectin binding in the parental strain. The extent of these reductions, compared with the parent, was reduced in the rsb mutants (rsbV > rsbU), especially at low SAL concentrations. Since generation of the free SigB protein usually requires a sequential rsbU-V-W-sigB activation cascade, the present phenotypic and genotypic data suggest key roles for both rsbU and rsbV in SAL-mediated activation of sigB in strains with a fully intact sigB operon.
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PMID:Salicylic acid activates sigma factor B by rsbU-dependent and -independent mechanisms. 1688 58

Increasing evidence suggests that heat acclimation and exogenous salicylic acid (SA) and abscisic acid (ABA) may lead to the enhancement of thermotolerance in plants. In this study, the roles that free SA, conjugated SA, ABA, and phosphatidylinositol-4,5-bisphosphate (PIP(2))-specific phospholipase C (PLC) play in thermotolerance development induced by heat acclimation (38 degrees C) were investigated. To evaluate their potential functions, three inhibitors of synthesis or activity were infiltrated into pea leaves prior to heat acclimation treatment. The results showed that the burst of free SA in response to heat acclimation could be attributed to the conversion of SA 2-O-D-glucose, the main conjugated form of SA, to free SA. Inhibition of ABA biosynthesis also resulted in a defect in the free SA peak during heat acclimation. In acquired thermotolerance assessment, the greatest weakness of antioxidant enzyme activity and the most severe heat injury (malondialdehyde content and degree of wilting) were found in pea leaves pre-treated with neomycin, a well-known inhibitor of PIP(2)-PLC activity. PsPLC gene expression was activated by exogenous ABA, SA treatments, and heat acclimation after pre-treatments with a SA biosynthesis inhibitor. From these results, PIP(2)-PLC appears to play a key role in free SA- and ABA-associated reinforcement of thermotolerance resulting from heat acclimation.
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PMID:Novel interrelationship between salicylic acid, abscisic acid, and PIP2-specific phospholipase C in heat acclimation-induced thermotolerance in pea leaves. 1690 2


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