Cytosolic phospholipase A2 mediates neuronal apoptosis induced by soluble oligomers of the amyloid‐β peptide

Recent data have revealed that soluble oligomeric forms of amyloid peptide (Aβ) may be the proximate effectors of the neuronal injury and death occurring in Alzheimer's disease (AD). However, the molecular mechanisms associated with the neuronal cell death induced by the nonfibrillar Aβ remain to be elucidated. In this study, we investigated the role of the cytosolic Ca2+‐dependent phospholipase A2 (cPLA2), and its associated metabolic pathway, i.e., the arachidonic acid (AA) cascade, in the apoptotic cell death induced by soluble oligomers of Aβ. The treatment of rat cortical neurons with low concentrations of soluble Aβ(1‐40) or Aβ(1‐42) peptide resulted in an early calcium‐dependent release of AA associated with a transient relocalization of cPLA2. Both cPLA2 antisense oligonucleotides and a selective inhibitor of cPLA2 activity abolished the release of AA from neurons and also protected cells against apoptosis induced by Aβ. Furthermore, inhibitors of the PKC, p38, and MEK/ERK pathways that are involved in cPLA2 phosphorylation and activation reduced Aβ‐induced cell death. Finally, we demonstrate that inhibitors of cyclooxygenase‐2 reduced the Aβ‐induced cell death by 55%. Our studies suggest a novel neuronal response of soluble oligomers of Aβ, which occurs through a cPLA2 signaling cascade and an AA‐dependent death pathway. This may prove to be crucial in AD processes and could provide important targets for drug development.