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Your search keyword '"PHOSPHOLIPASE-A2"' showing total 4 results
Start Over Descriptor "PHOSPHOLIPASE-A2" Topic arachidonic acid
4 results on '"PHOSPHOLIPASE-A2"'

1. A phospholipase A2-stimulating protein regulated by protein kinase C in Aplysia neurons

Author

Calignano, Antonio, Piomelli, Daniele, Sacktor, Todd C, and Schwartz, James H

Subjects
Biological Psychology, Biomedical and Clinical Sciences, Neurosciences, Psychology, Neurological, 12-Hydroxy-5, 8, 10, 14-eicosatetraenoic Acid, Animals, Aplysia, Chromatography, High Pressure Liquid, Chromatography, Ion Exchange, Electrophoresis, Polyacrylamide Gel, Enzyme Activation, Ganglia, Hydroxyeicosatetraenoic Acids, Kinetics, Molecular Weight, Neurons, Phospholipases A, Phospholipases A2, Protein Kinase C, Proteins, Trypsin, PHOSPHOLIPASE-A2, PHOSPHOLIPASE-A2-ACTIVATING PROTEIN, ARACHIDONIC ACID, PROTEIN KINASE-C, APLYSIA, SENSITIZATION, MEMORY, Cognitive Sciences, Neurology & Neurosurgery, Biological psychology
Abstract

We describe some properties on an Mr 30,000 thermolabile and trypsin-sensitive protein that activates phospholipase A2 (PLA2) and which was isolated from nervous tissue of the marine mollusk, Aplysia californica. A similar protein is present in rat cerebral cortex. This protein was partially purified from crude homogenates of nervous tissue by ion exchange chromatography on DEAE-Sephadex followed by size-exclusion high performance liquid chromatography (HPLC). It is loosely associated with membrane fractions, and is extracted by 0.05% Tween 20. Although similar in size to several previously described PLA2-stimulating proteins from non-neural mammalian cells and tissues, it differs from them in some aspects of biological activity. The protein promotes the release of eicosanoids from the membranes of intact Aplysia neurons prelabeled with [3H]arachidonic acid and appears to be an in vitro substrate for protein kinase C (PKC). PLA2-stimulating activity is greatly enhanced after exposing isolated ganglia to phorbol dibutyrate (PDBu) and is reduced by treatment with immobilized E. coli alkaline phosphatase. These observations suggest that phosphorylation of this stimulatory protein by PKC regulates PLA2 in neurons.

Published
1991

3. Possible involvement of arachidonic acid and eicosanoids in metamorphic events in Hydractinia echinata (Coelenterata; Hydrozoa)

Author

L. De Petrocellis, W. D. Lehmann, V. Di Marzo, M. Stephan, H. Beck, and Thomas Leitz

Subjects
Hydra, Indomethacin, Lipoxygenase, Biology, Hydractinia echinata, Gas Chromatography-Mass Spectrometry, PHOSPHOLIPASE-A2, chemistry.chemical_compound, Hydroxyeicosatetraenoic Acids, Animals, Masoprocol, 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid, Carbon Radioisotopes, PROTEIN-KINASE-C, 2ND MESSENGERSSIGNAL TRANSDUCTION INDUCE METAMORPHOSIS, Phospholipids, chemistry.chemical_classification, Arachidonic Acid, Aspirin, HYDRA-VULGARIS, Metamorphosis, Biological, General Medicine, Metabolism, biology.organism_classification, 5,8,11,14-Eicosatetraynoic Acid, Nordihydroguaiaretic acid, Enzyme, chemistry, Biochemistry, Eicosanoid, biology.protein, Eicosanoids, Animal Science and Zoology, Arachidonic acid, Cyclooxygenase
Abstract

Upon induction of metamorphosis, larvae of the marine hydroid Hydractinia echinata release [14C]-arachidonic acid from previously labeled endogenous sources. The lipoxygenase inhibitors nordihydroguaiaretic acid and 5,8,11,14-eicosatetraynoic acid inhibited metamorphosis induced by Cs+ and 1,2-sn-dioctanoylglycerol, whereas the inhibitors of cyclooxygenase, indomethacin, and acetylsalicylic acid were ineffective, suggesting a role for lipoxygenase metabolites of arachidonic acid in induction of metamorphosis. Lipoxygenase products in Hydractinia echinata were isolated and identified by gas chromatography/mass spectrometry. 8- and 12-HETE were the most abundant metabolites. In cytosolic fractions from larvae activity of an arachidonic acid metabolizing enzyme, presumably a lipoxygenase, was found. The metabolic product was identified by 1H-NMR and chiral phase HPLC as 8(R)-HETE. Its production was strongly inhibited by NDGA, but not by indomethacin. © 1994 Wiley-Liss, Inc.

Published
1994
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4. Hydrogen peroxide triggers activation of human platelets selectively exposed to nonaggregating concentrations of arachidonic acid and collagen

Author

Pratico, D., Iuliano, L., Fabio M. Pulcinelli, Bonavita, M. S., Gazzaniga, P. P., and Violi, F.

Subjects
RELEASE, MECHANISM, Serotonin, FREE-RADICALS, Arachidonic Acid, Dose-Response Relationship, Drug, L-Lactate Dehydrogenase, Platelet Aggregation, Hydrogen Peroxide, AGGREGATION, THROMBIN, In Vitro Techniques, Platelet Activation, METABOLITES, PHOSPHOLIPASE-A2, Thromboxane A2, STIMULATED HUMAN-PLATELETS, NEUTROPHILS, Humans, Calcium, Collagen
Abstract

The effects of H2O2 on platelet function were investigated in vitro and ex vivo. H2O2 (0.5 to 5 mumol/L) alone did not influence platelet function, but when it was combined with subthreshold concentrations of arachidonic acid or collagen, it induced platelet aggregation and serotonin release in a dose-dependent fashion. The increase in platelet aggregation was associated with thromboxane A2 production and was prevented by 100 mumol/L aspirin. The amplification of platelet response by H2O2 was also inhibited 2 hours after 300 mg aspirin was given to healthy subjects. H2O2 alone did not affect intraplatelet Ca++ influx or mobilization but, combined with subthreshold concentrations of arachidonic acid, it increased Ca++ mobilization. In platelets prelabeled with tritiated arachidonic acid, H2O2 induced tritium release in a dose-dependent fashion; this effect was prevented by mepacrine, an inhibitor of the phospholipase A2 enzyme. Platelet function was not affected by using H2O2 in combination with other agonists such as thrombin, calcium ionophore, or adenosine diphosphate. This study suggests that H2O2 triggers activation of platelets preexposed to agonists at subthreshold levels by stimulating arachidonic acid metabolism, likely by stimulating the phospholipase A2 enzyme. The stimulation of platelets by concentrations of H2O2 similar to those released by activated leukocytes may give new insights into the functional cooperation between leukocytes and platelets.

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