N-ethyl maleimide stimulates arachidonic acid release through activation of the signal-responsive phospholipase A2 in endothelial cells.
Treatment of bovine endothelial cells with the alkylator N-ethyl maleimide results in arachidonic acid mobilization. N-ethyl maleimide-stimulated arachidonic acid release was dose and time dependent and maximum release was achieved after 10-15 min with 50 microM N-ethyl maleimide, N-ethyl maleimide-stimulated arachidonic acid release could be prevented by pretreating the cells with the phospholipase A2 inhibitor quinacrine. Based on the finding that N-ethyl maleimide was not able to release oleic acid from oleic acid-preloaded cells, it was clear that the effect of N-ethyl maleimide was limited to an arachidonic acid-specific phospholipase. The effect of N-ethyl maleimide does not appear to be dependent on calcium, as shown by the observation that N-ethyl maleimide was not able to increase intracellular calcium concentration in FURA2-loaded cells. Pretreatment of the cells with staurosporine totally inhibited N-ethyl maleimide-stimulated arachidonic acid liberation. The tyrosine kinase inhibitor genistein was also able to significantly inhibit arachidonic acid release. It is concluded from the results obtained in this study that N-ethyl maleimide stimulates arachidonic acid release by stimulating the activity of a specific, signal-responsive phospholipase A2. Furthermore this activation is not mediated by intracellular calcium fluxes but by a stimulation of intracellular kinase activity which eventually leads to the activation of this signal-responsive phospholipase A2.
Division of Toxicology, Karolinska Institute, Stockholm, Sweden.
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EP
Neve
C S
CS
Boyer
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Moldéus
D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism*; D002417:Cattle; D002478:Cells, Cultured; D004727:Endothelium / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D004789:Enzyme Activation / Q000187:drug effects; D005033:Ethylmaleimide / Q000494:pharmacology*; D007700:Kinetics; D010741:Phospholipases A / Q000187:drug effects* / Q000378:metabolism* / Q000502:physiology; D054467:Phospholipases A2; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology*
D016718:Arachidonic Acid; D010741:Phospholipases A; D054467:Phospholipases A2; D005033:Ethylmaleimide