Paraquat induces lung alveolar epithelial cell apoptosis via Nrf-2-regulated mitochondrial dysfunction and ER stress
Paraquat induces lung alveolar epithelial cell apoptosis via Nrf-2-regulated mitochondrial dysfunction and ER stress
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DOI：
10.1007/s00204-012-0873-8
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发表时间：
2012-10-01
影响因子：
6.1
通讯作者：
Chen, Kuo-Liang
中科院分区：
文献类型：
--
作者：
Chen, Ya-Wen;Yang, Yuan-Ting;Chen, Kuo-Liang
百草枯（1，1 '-二甲基-4，4'-氯化联吡啶; PQ）是世界上广泛使用的除草剂。据报告，PQ是一种主要危害，因为它会导致肺损伤。然而，PQ诱导的肺毒性的分子机制仍需阐明。在此，我们发现，PQ显着降低细胞活力，增加亚G1亚二倍体DNA含量和caspase 3/7活性在肺泡上皮细胞衍生的L2细胞，这也导致线粒体功能障碍，并降低Bcl-2的mRNA表达和增加Bax，巴克，和p53。PQ处理后Bax和巴克蛋白表达增加。此外，PQ暴露于L2细胞时，ER应激相关信号基因（包括Grp 78、CHOP和caspase-12 mRNA）和蛋白质（包括磷酸化eIF-2 α、CHOP、Grp 78、calpain I和-II和caspase-12）的表达显著增加。PQ还降低了caspase-9/7/3蛋白的表达。接下来，我们研究了Nrf-2在PQ诱导的肺泡上皮细胞毒性中的作用。在L2细胞中，PQ诱导Nrf-2从胞质到细胞核的易位。转染Nrf-2 siRNA的细胞可明显逆转PQ诱导的细胞毒性，包括MMP的去极化，增加Bax、巴克、p53 mRNA的表达，降低Bcl-2 mRNA的表达，增加caspase 3/7活性、Grp 78、CHOP、caspase-12 mRNA和蛋白的表达，降低caspase-3原的表达。总之，这些结果表明，Nrf-2调节的线粒体和ER应激相关的途径参与PQ诱导的肺泡上皮细胞损伤。
Paraquat (1,1'-dimethyl-4,4'-bipyridinium chloride; PQ) is widely and commonly used as a herbicides in the world. PQ has been reported to be a major hazard because it causes lung injury. However, the molecular mechanisms underlying PQ-induced lung toxicity still need to be elucidated. Here, we found that PQ significantly decreases cell viability, increases sub-G1 hypodiploids DNA contents and caspase 3/7 activity in lung alveolar epithelial cell-derived L2 cells, which also caused mitochondrial dysfunction, and decreased the mRNA expression of Bcl-2 and increased that of Bax, Bak, and p53. Moreover, the protein expressions of Bax and Bak were increased in PQ-treated cells. In addition, when PQ was exposed to L2 cells, the expressions of ER stress-related signaling genes (including Grp78, CHOP, and caspase-12 mRNA) and proteins (including phospho-eIF-2 alpha, CHOP, Grp78, calpain I and -II, and caspase-12) were significantly increased. PQ also decreased the protein expressions of pro-caspase-9/7/3. Next, we investigated the role of Nrf-2 in PQ-induced alveolar epithelial cell toxicity. In L2 cells, PQ induced Nrf-2 translocation from the cytosol to the nucleus. Cells transfected with Nrf-2 siRNA significantly reversed the PQ-induced toxicity, including depolarization of MMP, increased the Bax, Bak, p53 mRNAs expression, decreased the Bcl-2 mRNA expression, increased the caspase 3/7 activity, Grp78, CHOP, and caspase-12 mRNAs and protein expression, and decreased that of pro-caspase-3. Taken together, these results suggest that Nrf-2-regulated mitochondria and ER stress-related pathways are involved in the PQ-induced alveolar epithelial cell injury.