Coronavirus endoribonuclease targets viral polyuridine sequences to evade activating host sensors
Coronavirus endoribonuclease targets viral polyuridine sequences to evade activating host sensors
复制标题
DOI：
10.1073/pnas.1921485117
复制
发表时间：
2020-04-07
影响因子：
11.1
通讯作者：
Baker, Susan C.
中科院分区：
文献类型：
--
作者：
Hackbart, Matthew;Deng, Xufang;Baker, Susan C.
冠状病毒（CoV）是一种正义RNA病毒，可从地方性宿主中出现并通过动物源性感染，导致显著的发病率和死亡率。CoV编码一种称为EndoU的核糖核酸内切酶，它有助于逃避宿主模式识别受体MDA 5，但EndoU活性的靶点尚不清楚。在这里，我们报道了EndoU从负义病毒RNA（称为PUN RNA）切割5 '-聚尿苷，PUN RNA是polyA模板RNA合成的产物。使用含有EndoU催化失活突变的病毒，与野生型感染的细胞相比，我们在细胞质中检测到更高丰度的PUN RNA。此外，我们发现，将PUN RNA导入细胞会刺激一种强有力的、依赖于MDA 5的干扰素应答，而去除RNA上的多聚尿苷延伸会抑制这种应答。总体而言，这项研究的结果表明PUN RNA是CoV MDA 5依赖性病原体相关分子模式（PAMP）。我们还建立了EndoU活性切割和限制这种PAMP积累的机制。由于EndoU活性在所有CoV中都高度保守，因此抑制该活性可以作为针对现有和新出现的CoV感染的治疗干预的方法。
Coronaviruses (CoVs) are positive-sense RNA viruses that can emerge from endemic reservoirs and infect zoonotically, causing significant morbidity and mortality. CoVs encode an endoribonuclease designated EndoU that facilitates evasion of host pattern recognition receptor MDA5, but the target of EndoU activity was not known. Here, we report that EndoU cleaves the 5'-polyuridines fromnegative-sense viral RNA, termed PUN RNA, which is the product of polyA-templated RNA synthesis. Using a virus containing an EndoU catalytic-inactive mutation, we detected a higher abundance of PUN RNA in the cytoplasm compared to wildtype-infected cells. Furthermore, we found that transfecting PUN RNA into cells stimulates a robust, MDA5-dependent interferon response, and that removal of the polyuridine extension on the RNA dampens the response. Overall, the results of this study reveal the PUN RNA to be a CoV MDA5-dependent pathogen-associated molecular pattern (PAMP). We also establish a mechanism for EndoU activity to cleave and limit the accumulation of this PAMP. Since EndoU activity is highly conserved in all CoVs, inhibiting this activity may serve as an approach for therapeutic interventions against existing and emerging CoV infections.