Chen Y C, Tsai S H, Lin-Shiau S Y, Lin J K
Institute of Biochemistry, College of Medicine, National Taiwan University, Taipei, ROC.
Mol Cell Biochem. 1999 Jul;197(1-2):147-59. doi: 10.1023/a:1006941630901.
Apoptosis has been hypothesized to be mediated through the induction of free radicals via oxidative pathway. In this study, we demonstrated the induction of cellular apoptosis by anoxia-hyperoxia shift, but not by anoxia or hyperoxia alone in NIH3T3 cells. The decrement of ROS by anoxia thus appears to be an essential early event leading to apoptosis. G1 arrest was detected in anoxia-treated cells, and postanoxic oxygen recovery could reverse this effect, and induce apoptosis. On analysis of the binding activity of AP-1, we found biphasic induction of binding ability in cells undergoing anoxia-hyperoxia shift. In the early stage of anoxia, a transitional increase of AP-1 binding activity was detected, which was reduced to the minimal levels after 24 h of anoxia. During the period of postanoxic hyperoxia treatment, the binding activity of AP-1 was reinduced and increased remarkably with time up to 24 h. These results were in accordance with the expressions of c-jun and c-fos proteins. Enhancement of poly(ADP-ribosyl)ation activities, especially ADP-ribosylation of histone H1 was detected in post-anoxic hyperoxia-treated cells, and cleavage of PARP and activation of caspase 3 were also observed in post-anoxic hyperoxia (recovery) treated cells, but not in anoxia-treated cells. We propose that the differential induction of c-jun/c-fos (AP-1) gene expressions and sequential activation of PARP activity are essential in anoxia/hyperoxia-induced apoptosis.
据推测，细胞凋亡是通过氧化途径诱导自由基介导的。在本研究中，我们证明了缺氧-复氧转换可诱导NIH3T3细胞发生细胞凋亡，而单纯缺氧或复氧则不能。因此，缺氧导致的活性氧减少似乎是导致细胞凋亡的一个重要早期事件。在缺氧处理的细胞中检测到G1期阻滞，缺氧后恢复氧气可逆转这种效应并诱导细胞凋亡。通过分析AP-1的结合活性，我们发现在经历缺氧-复氧转换的细胞中，其结合能力呈双相诱导。在缺氧早期，检测到AP-1结合活性有短暂增加，缺氧24小时后降至最低水平。在缺氧后复氧处理期间，AP-1的结合活性被重新诱导，并随时间显著增加，直至24小时。这些结果与c-jun和c-fos蛋白的表达一致。在缺氧后复氧处理的细胞中检测到多聚（ADP-核糖基）化活性增强，尤其是组蛋白H1的ADP-核糖基化，并且在缺氧后复氧（恢复）处理的细胞中也观察到PARP的裂解和caspase 3的激活，但在缺氧处理的细胞中未观察到。我们认为，c-jun/c-fos（AP-1）基因表达差异诱导和PARP活性的顺序激活在缺氧/复氧诱导的细胞凋亡中至关重要。
