Brewer Cynthia, Bonin Fanny, Bullock Paula, Nault Marie-Christine, Morin Jennifer, Imbeault Sophie, Shen T Y, Franks D J, Bennett Steffany A L
Neural Regeneration Laboratory, Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, Ontario, Canada.
J Neurochem. 2002 Sep;82(6):1502-11. doi: 10.1046/j.1471-4159.2002.01094.x.
The pro-inflammatory lipid mediator platelet activating factor (PAF: 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) accumulates in ischemia, epilepsy, and human immunodeficiency virus-1-associated dementia and is implicated in neuronal loss. The present study was undertaken to establish a role for its G-protein coupled receptor in regulating neurotoxicity. PC12 cells do not express PAF receptor mRNA as demonstrated by northern analysis and RT-PCR. In the absence of the G-protein coupled receptor, PAF (0.1-1 micro m) triggered chromatin condensation, DNA strand breaks, oligonucleosomal fragmentation, and nuclear disintegration characteristic of apoptosis. Lyso-PAF (0.001-1 micro m), the immediate metabolite of PAF, did not elicit apoptotic death. Concentrations of PAF or lyso-PAF that exceeded critical micelle concentration had physicochemical effects on plasma membrane resulting in necrosis. Apoptosis but not necrosis was inhibited by the PAF antagonist BN52021 (1-100 micro m) but not CV3988 (0.2-20 micro m). Ectopic PAF receptor expression protected PC12 transfectants from ligand-induced apoptosis. PAF receptor-mediated protection was inhibited by CV3988 (1 micro m). These data provide empirical evidence that: (i) PAF can initiate apoptosis independently of its G-protein coupled receptor; (ii) PAF signaling initiated by its G-protein coupled receptor is cytoprotective to PC12 cells; (iii) the pro- and anti-apoptotic effects of PAF on PC12 cells can be pharmacologically distinguished using two different PAF antagonists.
促炎脂质介质血小板活化因子（PAF：1-O-烷基-2-乙酰基-sn-甘油-3-磷酸胆碱）在缺血、癫痫和人类免疫缺陷病毒1型相关痴呆中蓄积，并与神经元丢失有关。本研究旨在确定其G蛋白偶联受体在调节神经毒性中的作用。Northern分析和逆转录聚合酶链反应（RT-PCR）表明，PC12细胞不表达PAF受体mRNA。在缺乏G蛋白偶联受体的情况下，PAF（0.1 - 1微摩尔）引发染色质浓缩、DNA链断裂、寡核小体片段化以及凋亡特有的核解体。PAF的直接代谢产物溶血PAF（0.001 - 1微摩尔）未引发凋亡死亡。超过临界胶束浓度的PAF或溶血PAF浓度对质膜有物理化学作用，导致坏死。PAF拮抗剂BN52021（1 - 100微摩尔）可抑制凋亡但不抑制坏死，而CV3988（0.2 - 20微摩尔）则无此作用。异位表达PAF受体可保护PC12转染细胞免受配体诱导的凋亡。CV3988（1微摩尔）可抑制PAF受体介导的保护作用。这些数据提供了以下实验证据：（i）PAF可独立于其G蛋白偶联受体引发凋亡；（ii）由其G蛋白偶联受体启动的PAF信号传导对PC12细胞具有细胞保护作用；（iii）使用两种不同的PAF拮抗剂可在药理学上区分PAF对PC12细胞的促凋亡和抗凋亡作用。
