Li Yuchi, Arita Yuko, Koo Hshi-Chi, Davis Jonathan M, Kazzaz Jeffrey A
The CardioPulmonary Research Institute, Winthrop-University Hospital, Suite 505, 222 Station Plaza N, Mineola, NY 11501, USA.
Am J Respir Cell Mol Biol. 2003 Dec;29(6):779-83. doi: 10.1165/rcmb.2003-0087RC. Epub 2003 Jul 3.
Oxidant insults can lead to apoptotic and nonapoptotic cell death. Lung epithelial cells exposed to high levels of oxygen do not die via apoptosis, but through a much slower, morphologically distinct process involving cell and nuclear swelling. In contrast, H2O2 induces a rapid apoptotic cell death. We first assessed the effect of oxidant exposure on activator protein-1 (c-Jun and Fos) and c-Jun N-terminal kinase (JNK) regulation in MLE12 cells. Both oxidants induced c-Jun and Fos expression, albeit with a different pattern of regulation-hyperoxia (95% O2) induced a biphasic response, whereas H2O2 (500 microM) induced a sustained response. We then examined the role of JNK by Western blot, JNK activity assay, and a pull-down assay and observed an identical pattern of regulation. To assess whether JNK functions in a pro-death or pro-survival capacity, we generated stable cell lines that constitutively express a dominant-negative mutation of JNK resulting in significant inhibition of JNK activity. Inhibition of the JNK pathway in this manner prevented hyperoxic and H2O2-induced cell death. These results demonstrate that hyperoxic cell death is pathway-driven and that both modes of death involve the JNK signaling pathway.
氧化损伤可导致细胞凋亡和非凋亡性死亡。暴露于高氧环境中的肺上皮细胞并非通过凋亡死亡，而是通过一个更为缓慢、形态学上截然不同的过程，该过程涉及细胞和细胞核肿胀。相比之下，过氧化氢可诱导快速的细胞凋亡性死亡。我们首先评估了氧化应激对MLE12细胞中活化蛋白-1（c-Jun和Fos）以及c-Jun氨基末端激酶（JNK）调控的影响。两种氧化剂均诱导了c-Jun和Fos的表达，尽管调控模式不同——高氧（95% O2）诱导双相反应，而过氧化氢（500微摩尔）诱导持续反应。然后，我们通过蛋白质印迹法、JNK活性测定和下拉测定法研究了JNK的作用，并观察到相同的调控模式。为了评估JNK是以促死亡还是促生存的能力发挥作用，我们构建了稳定细胞系，这些细胞系组成性表达JNK的显性负性突变体，从而显著抑制JNK活性。以这种方式抑制JNK途径可防止高氧和过氧化氢诱导的细胞死亡。这些结果表明，高氧诱导的细胞死亡由信号通路驱动，且两种死亡模式均涉及JNK信号通路。
