Food, Drug and Chemical Toxicology Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), M.G. Marg, Post Box No. 80, Lucknow 226001, India; Academy of Scientific and Innovative Research (AcSIR), New Delhi, India.
Division of Parasitology, CSIR-Central Drug Research Institute, B.S. 10/1, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226031, India.
Toxicol Lett. 2014 May 16;227(1):29-40. doi: 10.1016/j.toxlet.2014.02.024. Epub 2014 Mar 12.
Zinc oxide nanoparticles (ZnO NPs) induced macrophage cell death and its mechanism remains to be solved. Herein, we report that ZnO NPs induced ROS generation by depleting antioxidant enzymes, increasing lipid peroxidation and protein carbonyl contents in macrophages. The oxidative stress was induced by the inhibition of Nrf2 transcription factor release. ZnO NPs also activated the cleavage of apoptosis markers like caspases 3, 8 and 9. γH2Ax activation and cleavage of poly (ADP-ribose) polymerase (PARP) that are known indicators of genotoxicity were found to be activated by following p53, p21/waf1 signaling. ZnO NPs increased the number of autophagosomes and autophagy marker proteins such as microtubule-associated protein 1 light chain 3-isoform II (MAP-LC3-II) and Beclin 1 after 0.5-24h of treatment. Phosphorylated Akt, PI3K and mTOR were significantly decreased on ZnO NPs exposure. Moreover, the apoptotic and autophagic cell death could be inhibited on blocking of ROS generation by N-acetylcysteine (NAC) which demonstrated the critical role of ROS in both types of cell death. In addition, inhibition of LC3-II by siRNA-dependent knockdown attenuated the cleavage of caspase 3. This study demonstrates autophagy supports apoptosis on ZnO NPs exposure.
氧化锌纳米粒子（ZnO NPs）诱导巨噬细胞死亡的机制仍有待解决。在此，我们报告 ZnO NPs 通过耗竭抗氧化酶、增加巨噬细胞中的脂质过氧化和蛋白质羰基含量来诱导 ROS 的产生。氧化应激是通过抑制 Nrf2 转录因子的释放而引起的。ZnO NPs 还激活了凋亡标志物如 caspase 3、8 和 9 的切割。γH2Ax 的激活和多聚（ADP-核糖）聚合酶（PARP）的切割，这些都是遗传毒性的已知标志物，被发现通过 p53、p21/waf1 信号通路被激活。在 0.5-24 小时的处理后，ZnO NPs 增加了自噬体的数量和自噬标志物蛋白，如微管相关蛋白 1 轻链 3-异构体 II（MAP-LC3-II）和 Beclin 1。在 ZnO NPs 暴露后，磷酸化 Akt、PI3K 和 mTOR 显著减少。此外，通过 N-乙酰半胱氨酸（NAC）阻断 ROS 的产生可以抑制细胞凋亡和自噬性细胞死亡，这表明 ROS 在这两种类型的细胞死亡中都起着关键作用。此外，通过 siRNA 依赖性敲低抑制 LC3-II 可减弱 caspase 3 的切割。这项研究表明，自噬在 ZnO NPs 暴露时支持细胞凋亡。
