Japanese encephalitis virus activates autophagy through XBP1 and ATF6 ER stress sensors in neuronal cells
Japanese encephalitis virus activates autophagy through XBP1 and ATF6 ER stress sensors in neuronal cells
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DOI：
10.1099/jgv.0.000792
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发表时间：
2017-05-01
影响因子：
3.8
通讯作者：
Kalia, Manjula
中科院分区：
文献类型：
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作者：
Sharma, Manish;Bhattacharyya, Sankar;Kalia, Manjula
内质网（ER）应激和自噬是RNA病毒感染的关键细胞反应。最近的研究表明，日本脑炎病毒（JEV）诱导的自噬对病毒在小鼠神经元细胞和胚胎成纤维细胞中的复制产生负面影响，并延迟病毒诱导的细胞死亡。在这里，我们评估了在JEV感染过程中ER应激途径在诱导自噬中的作用。我们观察到神经元细胞的JEV感染导致eIF 2 alpha/PERK、IRE 1/XBP 1和ATF 6介导的所有三种ER应激传感器激活。通过SQSTM 1和LC 3-II水平监测的自噬诱导动力学抑制ER应激的激活。通过siRNA介导的蛋白质消耗和PERK抑制剂抑制eIF 2 α/PERK通路对自噬和JEV复制没有影响。然而，单独或组合的XBP 1和ATF 6的耗尽阻止了自噬诱导并显著增强了JEV诱导的细胞死亡。耗尽XBP 1或ATF 6的JEV感染的细胞显示ER分子伴侣、ERAD组分和自噬基因的转录减少，导致关键的自噬效应物ATG 3和BECLIN-1的蛋白水平降低。相反，在JEV感染的细胞中ER应激的药理学诱导进一步增强自噬并降低病毒滴度。因此，我们的研究表明，在病毒感染的细胞中，ER应激途径和自噬之间存在着至关重要的联系，并且这些过程在病毒感染期间受到高度调节。
Endoplasmic reticulum (ER) stress and autophagy are key cellular responses to RNA virus infection. Recent studies have shown that Japanese encephalitis virus (JEV)-induced autophagy negatively influences virus replication in mouse neuronal cells and embryonic fibroblasts, and delays virus-induced cell death. Here, we evaluated the role of ER stress pathways in inducing autophagy during JEV infection. We observed that JEV infection of neuronal cells led to activation of all three sensors of ER stress mediated by eIF2 alpha/PERK, IRE1/XBP1 and ATF6. The kinetics of autophagy induction as monitored by levels of SQSTM1 and LC3-II paralleled activation of ER stress. Inhibition of the eIF2 alpha/PERK pathway by siRNA-mediated depletion of proteins and by the PERK inhibitor had no effect on autophagy and JEV replication. However, depletion of XBP1 and ATF6, alone or in combination, prevented autophagy induction and significantly enhanced JEV-induced cell death. JEV-infected cells depleted of XBP1 or ATF6 showed reduced transcription of ER chaperones, ERAD components and autophagy genes, resulting in reduced protein levels of the crucial autophagy effectors ATG3 and BECLIN-1. Conversely, pharmacological induction of ER stress in JEV-infected cells further enhanced autophagy and reduced virus titres. Our study thus demonstrates that a crucial link exists between the ER stress pathways and autophagy in virus-infected cells, and that these processes are highly regulated during virus infection.