Document Detail


Phosphatidylethanol stimulates calcium-dependent cytosolic phospholipase A(2) activity of a macrophage cell line (RAW 264.7).
MedLine Citation:
PMID:  10895054     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The synthesis of inflammation mediators produced from arachidonic acid is regulated primarily by the cellular concentration of free arachidonic acid. Since intracellular arachidonic acid is almost totally present as phospholipid esters, the concentration of intracellular arachidonic acid is primarily dependent on the balance between the release of arachidonic acid from membrane phospholipids and the uptake of arachidonic acid into membrane phospholipids. Cytosolic phospholipase A(2) is a calciumdependent enzyme that catalyzes the stimulus-coupled hydrolysis of arachidonic acid from membrane phospholipids. Following exposure of macrophages to various foreign or endogenous stimulants, cytosolic phospholipase A(2) is activated. Treatment with these compounds may also stimulate phospholipase D activity, and, in the presence of ethanol, phospholipase D catalyzes the synthesis of phosphatidylethanol. A cell-free system was used to evaluate the effect of phosphatidylethanol on cytosolic phospholipase A(2) activity. Phosphatidylethanol (0.5 microM) added to 1-stearoyl-2-[(3)H]-arachidonoyl-sn-glycero-3-phosphocholine vesicles stimulated cytosolic phospholipase A(2) activity. However, high concentrations (20-100 microM) of phosphatidylethanol inhibited cytosolic phospholipase A(2) activity. Phosphatidic acid, the normal phospholipase D product, also stimulated cytosolic phospholipase A(2) activity at 0.5 microM, but had an inhibitory effect on cytosolic phospholipase A(2) activity at concentrations of 50 and 100 microM. Ethanol (20-200 mM), the precursor of phosphatidylethanol, added directly to the assay did not alter cytosolic phospholipase A(2) activity. These results suggest that phosphatidylethanol alters the physical properties of the substrate, and at lower concentrations of anionic phospholipids the substrate is more susceptible to hydrolysis. However, at high concentrations, phosphatidylethanol either reverses the alterations in physical properties of the substrate or phosphatidylethanol may be competing as the substrate. Both interactions may result in lower cytosolic phospholipase A(2) activity.
Authors:
C Y Chang; K R Farrell; R C Baker
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of biomedical science     Volume:  7     ISSN:  1021-7770     ISO Abbreviation:  J. Biomed. Sci.     Publication Date:    2000 Jul-Aug
Date Detail:
Created Date:  2000-08-21     Completed Date:  2000-08-21     Revised Date:  2003-11-14    
Medline Journal Info:
Nlm Unique ID:  9421567     Medline TA:  J Biomed Sci     Country:  SWITZERLAND    
Other Details:
Languages:  eng     Pagination:  311-6     Citation Subset:  IM    
Copyright Information:
Copyright 2000 National Science Council, ROC and S. Karger AG, Basel
Affiliation:
Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, MS 39216, USA.
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MeSH Terms
Descriptor/Qualifier:
Animals
Arachidonic Acid / metabolism
Calcium / metabolism*
Cell Extracts
Chelating Agents / pharmacology
Cytosol / drug effects,  enzymology*
Enzyme Activation / drug effects
Ethanol / pharmacology
Glycerophospholipids / pharmacology*
Hydrolysis / drug effects
Kinetics
Liposomes / chemistry,  drug effects,  metabolism
Macrophages / cytology,  enzymology*
Mice
Phosphatidic Acids / pharmacology
Phosphatidylcholines / metabolism
Phospholipases A / metabolism*
Tumor Cells, Cultured
Chemical
Reg. No./Substance:
0/Cell Extracts; 0/Chelating Agents; 0/Glycerophospholipids; 0/Liposomes; 0/Phosphatidic Acids; 0/Phosphatidylcholines; 0/phosphatidylethanol; 506-32-1/Arachidonic Acid; 64-17-5/Ethanol; 7440-70-2/Calcium; EC 3.1.1.-/Phospholipases A

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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