Silica nanoparticles induce autophagosome accumulation via activation of the EIF2AK3 and ATF6 UPR pathways in hepatocytes
Silica nanoparticles induce autophagosome accumulation via activation of the EIF2AK3 and ATF6 UPR pathways in hepatocytes
复制标题
二氧化硅纳米粒子通过激活肝细胞中的 EIF2AK3 和 ATF6 UPR 途径诱导自噬体积累
DOI：
10.1080/15548627.2018.1458174
复制
发表时间：
2018-01-01
期刊：
影响因子：
13.3
通讯作者：
Sun, Zhiwei
中科院分区：
文献类型：
--
作者：
Wang, Ji;Li, Yang;Sun, Zhiwei
摘要自噬功能障碍是纳米颗粒的一种潜在毒性作用。以往的研究表明，二氧化硅纳米颗粒（SiNPs）可诱导巨自噬/自噬功能障碍，但其确切机制尚不清楚。因此，本研究调查了SiNPs增强自噬体合成的分子机制，然后导致自噬功能障碍。首先，使用透射电子显微镜、激光扫描共聚焦显微镜和蛋白质印迹分析来验证SiNPs对自噬和自噬通量的影响。随后，证实内质网（ER）应激的激活是通过EIF 2AK 3和ATF 6 UPR途径而不是ERN 1-XBP 1途径，沿着下游ATF 4和DDIT 3的上调。此后，使用ER应激抑制剂4-苯基丁酸酯（4-PBA）来验证SiNP诱导的自噬可以受到ER应激的影响。此外，采用专门的慢病毒shRNA来确定自噬是通过特异性激活EIF 2AK 3和ATF 6 UPR途径诱导的。最后，发现在ER应激中，下游的ATF 4和DDIT 3转录上调2个自噬基因LC 3B和ATG 12，这有助于SiNP增强自噬体的合成。总之，这些数据表明SiNP通过激活肝细胞中的EIF 2AK 3和ATF 6 UPR途径诱导自噬体积累，这为SiNP诱导的自噬功能障碍的详细分子机制提供了新的见解，特别是UPR途径如何调节关键的自噬基因。本工作为纳米硅的毒性效应研究和风险评估提供了新的证据。
ABSTRACT Autophagy dysfunction is a potential toxic effect of nanoparticles. Previous studies have indicated that silica nanoparticles (SiNPs) induce macroautophagy/autophagy dysfunction, while the precise mechanisms remain uncertain. Hence, the present study investigated the molecular mechanisms by which SiNPs enhanced autophagosome synthesis, which then contributed to autophagy dysfunction. First, the effects of SiNPs on autophagy and autophagic flux were verified using transmission electron microscopy, laser scanning confocal microscopy, and western blot assays. Then, the activation of endoplasmic reticular (ER) stress was validated to be through the EIF2AK3 and ATF6 UPR pathways but not the ERN1-XBP1 pathway, along with the upregulation of downstream ATF4 and DDIT3. Thereafter, the ER stress inhibitor 4-phenylbutyrate (4-PBA) was used to verify that SiNP-induced autophagy could be influenced by ER stress. Furthermore, specialized lentiviral shRNA were employed to determine that autophagy was induced via specific activation of the EIF2AK3 and ATF6 UPR pathways. Finally, the 2 autophagic genes LC3B and ATG12 were found to be transcriptionally upregulated by downstream ATF4 and DDIT3 in ER stress, which contributed to the SiNP-enhanced autophagosome synthesis. Taken together, these data suggest that SiNPs induced autophagosome accumulation via the activation of the EIF2AK3 and ATF6 UPR pathways in hepatocytes, which offers a new insight into detailed molecular mechanisms underlying SiNP-induced autophagy dysfunction, and specifically how UPR pathways regulate key autophagic genes. This work provides novel evidence for the study of toxic effects and risk assessment of SiNPs.