Involvement of Ca2+-independent phospholipase A(2) isoforms in oxidant-induced neural cell death

作者：Peterson Brianna; Knotts Taylor; Cummings Brian S^*

来源：NeuroToxicology, 2007, 28(1): 150-160.

DOI：10.1016/j.neuro.2006.09.006

• phospholipase A(2)
• phospholipids
• neural cells
• necrosis
• electrospray ionization-mass spectrometry

This study determined the roles of Ca2+-independent PLA(2) (iPLA(2)) in phospholipid chemistry and oxidant-induced cell death in human astrocytes. A 172 cells expressed both cytosolic Group VIA (iPLA(2)beta) and microsomal Group VIB (iPLA(2)gamma) PLA(2) as determined by activity assays and immunoblot analysis. Inhibition of total iPLA(2) activity using racemic bromoenol lactone (BEL, 2.5 mu M) decreased the expression of 14:0-16:0 phosphatidylcholine (PtdCho) 15% and increased 18:0-18:1-PtdCho expression 15%. Treatment of cells with the iPLA(2)gamma specific inhibitor R-BEL decreased 14:0-16:0-PtdCho 35%, 16:0-16:0-PtdCho 15% and induced a 35% increase in 18:0-18:1-PtdCho. In contrast, treatment of cells with the iPLA(2)beta inhibitor S-BEL did not alter any phospholipid studied. To determine the roles of iPLA(2) in oxidant-induced cell death, A172 cells were exposed to hydrogen peroxide (H2O2) or tert-butylhydroperoxide (TBHP); both induced time- and concentration-dependent increases in cell death as assessed by annexin V and propidium iodide staining. Treatment of cells with racemic-BEL alone did not induce cell death. However, pretreatment with BEL prior to H2O2 (500 mu M) or TBHP (200 mu M) significantly increased necrosis as determined by increases in propidium iodide staining. Treatment with BEL prior to exposure to oxidants accelerated the loss of ATP levels, but not the formation of reactive oxygen species. These data support the hypothesis that iPLA(2) mediates oxidant-induced neural cell death and demonstrates differential roles of iPLA(2) isoforms in physiological and pathological events.

• 出版日期2007-1