RNase L Induces Autophagy via c-Jun N-terminal Kinase and Double-stranded RNA-dependent Protein Kinase Signaling Pathways
RNase L Induces Autophagy via c-Jun N-terminal Kinase and Double-stranded RNA-dependent Protein Kinase Signaling Pathways
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DOI：
10.1074/jbc.m112.399964
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发表时间：
2012-12-21
影响因子：
4.8
通讯作者：
Malathi, Siddiqui Krishnamurthy
中科院分区：
文献类型：
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作者：
Adnan, Mohammad;Malathi, Siddiqui Krishnamurthy
自噬是介导细胞蛋白质、细胞器和病原体的隔离、降解和再循环的严格调节机制。与自噬相关的几种蛋白质调节宿主对病毒感染的反应。核糖核酸酶L（RNase L）在病毒感染期间被激活，并切割细胞和病毒单链RNA，包括核糖体中的rRNA。在这里，我们证明了RNase L的直接激活协调c-Jun N-末端激酶（JNK）和双链RNA依赖性蛋白激酶（PKR）的激活，以诱导自噬，其标志是自噬空泡的积累，p62（SQSTM 1）降解和微管相关蛋白轻链3-I（LC 3-I）转化为LC 3-II。因此，用JNK或PKR的药理学抑制剂和缺乏JNK 1/2或PKR的小鼠胚胎成纤维细胞（MEF）处理细胞显示降低的自噬水平。此外，RNase L诱导的JNK活性促进Bcl-2磷酸化，破坏Beclin 1-Bcl-2复合物并刺激自噬。与RNase L敲除（KO）MEFs相比，脑心肌炎病毒（EMCV）或仙台病毒的病毒感染导致野生型（WT）MEFs中更高水平的自噬。使用巴弗洛霉素A1或3-甲基腺嘌呤抑制RNA酶L诱导的自噬在初始阶段抑制病毒生长;在后期阶段自噬促进病毒复制，抑制抗病毒作用。由激活的RNase L诱导的自噬不依赖于干扰素（IFN）的旁分泌效应。我们的研究结果表明RNase L在诱导自噬中的新作用影响了病毒发病机制的结果。
Autophagy is a tightly regulated mechanism that mediates sequestration, degradation, and recycling of cellular proteins, organelles, and pathogens. Several proteins associated with autophagy regulate host responses to viral infections. Ribonuclease L (RNase L) is activated during viral infections and cleaves cellular and viral single-stranded RNAs, including rRNAs in ribosomes. Here we demonstrate that direct activation of RNase L coordinates the activation of c-Jun N-terminal kinase (JNK) and double-stranded RNA-dependent protein kinase (PKR) to induce autophagy with hallmarks as accumulation of autophagic vacuoles, p62(SQSTM1) degradation and conversion of Microtubule-associated Protein Light Chain 3-I (LC3-I) to LC3-II. Accordingly, treatment of cells with pharmacological inhibitors of JNK or PKR and mouse embryonic fibroblasts (MEFs) lacking JNK1/2 or PKR showed reduced autophagy levels. Furthermore, RNase L-induced JNK activity promoted Bcl-2 phosphorylation, disrupted the Beclin1-Bcl-2 complex and stimulated autophagy. Viral infection with Encephalomyocarditis virus (EMCV) or Sendai virus led to higher levels of autophagy in wild-type (WT) MEFs compared with RNase L knock out (KO) MEFs. Inhibition of RNase L-induced autophagy using Bafilomycin A1 or 3-methyladenine suppressed viral growth in initial stages; in later stages autophagy promoted viral replication dampening the antiviral effect. Induction of autophagy by activated RNase L is independent of the paracrine effects of interferon (IFN). Our findings suggest a novel role of RNase L in inducing autophagy affecting the outcomes of viral pathogenesis.