Zhao Jianmei, Tang Cuiying, Nie Xiaoke, Xi Hanqing, Jiang Shengyang, Jiang Junkang, Liu Suyi, Liu Xipeng, Liang Lingwei, Wan Chunhua, Yang Jianbin
Department of Pediatrics, Affiliated Hospital of Nantong University, Nantong, 226001, Jiangsu Province, China.
Department of Nutrition and Food Hygiene, School of Public Health, Nantong University, Nantong, 226001, China.
Environ Toxicol. 2016 Sep;31(9):1068-79. doi: 10.1002/tox.22116. Epub 2015 Apr 10.
The environmental toxicant TCDD may elicit cytotoxic effects by inducing reactive oxygen species (ROS) generation. Autophagy is one of the first lines of defense against oxidative stress damage. Herein, we investigated whether autophagy played a regulatory role in TCDD-induced neurotoxicity. Here, we showed that TCDD exposure caused marked autophagy in SH-SY5Y cells, whose dose range was close to that inducing apoptosis. Electron microscopic and Western blot analyses revealed that TCDD induced autophagy at a starting dose of approximate 100 nM. Interestingly, 100-200 nM TCDD exposure resulted in obviously decreased cell viability and evident apoptotic phenotype. Furthermore, the levels of pro-apoptotic molecules, Bax and cleaved-PARP, increased significantly, whereas Bcl2 declined after exposed to 100 nM TCDD. In addition, the apoptosis was verified using flow cytometrical analysis. These data strongly suggested that TCDD induced both autophagy and apoptosis at a similar dose range in SH-SY5Y cells. Interestingly, pretreatment with ROS scavenger, N-acetyl-cysteine (NAC), could effectively block both TCDD-induced apoptosis and autophagy. More surprisingly, inhibition of autophagy with 3-methyladenine (3MA), remarkably augmented TCDD-induced apoptosis. The findings implicated that the onset of autophagy might serve as a protective mechanism to ameliorate ROS-triggered cytotoxic effects in human SH-SY5Y neuronal cells under TCDD exposure. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1068-1079, 2016.
环境毒物2,3,7,8-四氯二苯并对二恶英（TCDD）可能通过诱导活性氧（ROS）生成而引发细胞毒性作用。自噬是抵御氧化应激损伤的第一道防线之一。在此，我们研究了自噬是否在TCDD诱导的神经毒性中发挥调节作用。在此，我们表明TCDD暴露在SH-SY5Y细胞中引起明显的自噬，其剂量范围接近诱导凋亡的剂量范围。电子显微镜和蛋白质印迹分析表明，TCDD在约100 nM的起始剂量下诱导自噬。有趣的是，暴露于100 - 200 nM的TCDD导致细胞活力明显下降和明显的凋亡表型。此外，促凋亡分子Bax和裂解的聚（ADP-核糖）聚合酶（PARP）的水平显著增加，而在暴露于100 nM TCDD后Bcl2下降。此外，使用流式细胞术分析验证了凋亡。这些数据强烈表明，TCDD在SH-SY5Y细胞中的相似剂量范围内诱导自噬和凋亡。有趣的是，用ROS清除剂N-乙酰半胱氨酸（NAC）预处理可有效阻断TCDD诱导的凋亡和自噬。更令人惊讶的是，用3-甲基腺嘌呤（3MA）抑制自噬显著增强了TCDD诱导的凋亡。这些发现表明，在TCDD暴露下，自噬的启动可能作为一种保护机制来减轻人SH-SY5Y神经元细胞中ROS触发的细胞毒性作用。©2015威利期刊公司。《环境毒理学》31: 1068 - 1079, 2016。
