N-ethyl maleimide stimulates arachidonic acid release through activation of the signal-responsive phospholipase A2 in endothelial cells

• Published in: Biochemical pharmacology 1995-01, Vol.49 (1), p.57-63
• Main Authors: Neve, E P, Boyer, C S, Moldéus, P
• Format: Article
• Language: English
• Subjects: Animals; Arachidonic Acid - metabolism; Cattle; Cells, Cultured; Endothelium - drug effects; Endothelium - metabolism; Endothelium - physiology; Enzyme Activation - drug effects; Ethylmaleimide - pharmacology; Kinetics; Phospholipases A - drug effects; Phospholipases A - metabolism; Phospholipases A - physiology; Phospholipases A2; Signal Transduction - drug effects; Signal Transduction - physiology
• ISSN: 0006-2952
• DOI: 10.1016/0006-2952(94)00308-9

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.