Studies on Plasmalogen-Selective Phospholipase A2 in Brain

Plasmalogen-selective phospholipase A2 (PlsEtn-PLA2) has been purified from pig brain using multiple column chromatographic procedure. The purified enzyme migrates as a single band on polyacrylamide. It is stimulated by Triton X-100 and inhibited by sodium deoxycholate. Purified PlsEtn-PLA2 is inhibited by iodoacetate, and this inhibition can be prevented by β-meracaptoethanol. Treatment of neuronal cell cultures with kainic acid stimulates PlsEtn-PLA2 activity in a dose-dependent manner, and this stimulation can be blocked by Ly294486, a selective kainic acid receptor antagonist. Activities of PlsEtn-PLA2 are markedly increased in plasma membrane and synaptosomal plasma membrane fraction prepared from nucleus basalis and hippocampal region of brains from Alzheimer disease patients compared to age-matched controls. It is proposed that accumulation of ceramide and increased expression of cytokines may be responsible for the stimulation of PlsEtn-PLA2 in Alzheimer disease.