Slater A F, Nobel C S, Maellaro E, Bustamante J, Kimland M, Orrenius S
Institute of Environmental Medicine, Karolinska Institute, Stockholm, Sweden.
Biochem J. 1995 Mar 15;306 ( Pt 3)(Pt 3):771-8. doi: 10.1042/bj3060771.
Oxidative stress has recently been suggested to be a mediator of apoptotic cell death [Buttke and Sandstrom (1994) Immunology Today 15, 7-10], although evidence that this phenomenon is a widespread component of apoptosis is lacking. When rat thymocytes were exposed to the glucocorticoid methylprednisolone (MPS), a progressive increase in intracellular peroxides and a decrease in glutathione (GSH) were observed to accompany the onset of apoptosis. Using Percoll density gradients to isolate subpopulations of thymocytes at different stages of apoptosis, the increase in peroxide content was found to be restricted to apoptotic cells, while a significant depletion of GSH and reduced protein thiol was detected in both pre-apoptotic and fully apoptotic cells. To investigate the biological significance of these redox changes, the free radical spin traps 5,5-dimethyl-1-pyrroline-1-oxide (DMPO) and 3,3,5,5-tetramethyl-1-pyrroline-1-oxide (TMPO), and the related nitroxide-radical antioxidant 2,2,6,6-tetramethyl-1-piperidinyl-1-oxyl (TEMPO) were tested as inhibitors of thymocyte apoptosis. The cell shrinkage and DNA fragmentation induced by four different initiators of apoptosis were reduced by each compound. TEMPO inhibition of both etoposide- and MPS-induced thymocyte DNA fragmentation was also found to correlate with an increase in intracellular GSH, providing support for the proposal that its antioxidant properties were responsible for the observed protective activity. We conclude that some form of intracellular oxidation (here measured indirectly by changes in intracellular GSH and peroxide levels) is required during thymocyte apoptosis even when this process is initiated by an agent that does not exert a direct oxidant action.
最近有人提出氧化应激是凋亡性细胞死亡的介质[巴特克和桑德斯特罗姆（1994年），《今日免疫学》15卷，7 - 10页]，尽管缺乏证据表明这种现象是凋亡的一个普遍组成部分。当大鼠胸腺细胞暴露于糖皮质激素甲基泼尼松龙（MPS）时，观察到细胞内过氧化物逐渐增加，谷胱甘肽（GSH）减少，同时伴随凋亡的开始。使用Percoll密度梯度分离处于凋亡不同阶段的胸腺细胞亚群，发现过氧化物含量的增加仅限于凋亡细胞，而在凋亡前期和完全凋亡的细胞中均检测到GSH显著减少和蛋白质硫醇减少。为了研究这些氧化还原变化的生物学意义，测试了自由基自旋捕获剂5,5 - 二甲基 - 1 - 吡咯啉 - 1 - 氧化物（DMPO）和3,3,5,5 - 四甲基 - 1 - 吡咯啉 - 1 - 氧化物（TMPO）以及相关的氮氧化物自由基抗氧化剂2,2,6,6 - 四甲基 - 1 - 哌啶基 - 1 - 氧基（TEMPO）作为胸腺细胞凋亡的抑制剂。每种化合物都减少了由四种不同凋亡启动剂诱导的细胞收缩和DNA片段化。还发现TEMPO对依托泊苷和MPS诱导的胸腺细胞DNA片段化的抑制作用与细胞内GSH的增加相关，这支持了其抗氧化特性是观察到的保护活性的原因这一观点。我们得出结论，即使胸腺细胞凋亡过程是由不具有直接氧化作用的试剂引发的，在凋亡过程中也需要某种形式的细胞内氧化（此处通过细胞内GSH和过氧化物水平的变化间接测量）。
