A mechanism for the inhibition of DNA-PK-mediated DNA sensing by a virus.
A mechanism for the inhibition of DNA-PK-mediated DNA sensing by a virus.
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DOI：
10.1371/journal.ppat.1003649
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发表时间：
2013
期刊：
影响因子：
6.7
通讯作者：
Smith GL
中科院分区：
文献类型：
--
作者：
Peters NE;Ferguson BJ;Mazzon M;Fahy AS;Krysztofinska E;Arribas-Bosacoma R;Pearl LH;Ren H;Smith GL
先天性免疫系统在对病原体感染的应答中是关键的，并且其通过结合至病原体相关分子模式（PAMP）的模式识别受体（PRR）而被激活。在病毒感染期间，病毒核酸（例如DNA病毒的基因组）的直接识别对于先天免疫的激活非常重要。最近，DNA依赖性蛋白激酶（DNA-PK），由Ku 70/Ku 80异源二聚体和催化亚基DNA-PKcs组成的异源三聚体复合物被鉴定为DNA的细胞质PRR，其对于细胞内DNA和DNA病毒感染的先天免疫应答是重要的。在这里，我们表明，牛痘病毒（VACV）已经发展到抑制这种功能的DNA-PK的高度保守的蛋白质C16，这是已知的毒力，但通过一个未知的机制表达。提供的数据显示，C16直接结合Ku异源二聚体，从而抑制成纤维细胞中对DNA的先天免疫应答，其特征在于细胞因子和趋化因子的产生减少。在机制上，C16通过阻断DNA-PK与DNA的结合而起作用，这与降低的DNA-PK依赖性DNA传感相关。C16的C-末端区域足以结合Ku，并且这种活性在C16的天花病毒（VARV）直向同源物中是保守的。相反，在该结构域中缺失5个氨基酸足以从减毒疫苗株修饰的安卡拉牛痘病毒（MVA）中敲除该功能。在体内缺乏C16的VACV突变体诱导更高水平的细胞因子和趋化因子感染后早期相比，对照病毒，证实了这种毒力因子在减弱先天免疫反应的作用。总的来说，这项研究描述了痘病毒蛋白对DNA-PK依赖性DNA传感的抑制，增加了DNA-PK是DNA病毒先天免疫的关键组分的证据。为了对入侵的细菌或病毒（病原体）产生免疫反应，宿主必须检测来自病原体的外来分子。病原体具有被称为病原体相关分子模式（PAMP）的保守特征，其不同于宿主细胞，并且被宿主使用特定传感器（称为模式识别受体，PRR）识别。PAMP的一个实例是细胞质中的DNA。细胞质DNA激活先天免疫系统，但PRR负责仍然不完全了解。最近发现了一种这样的PRR，DNA-PK。在这里，我们证明了牛痘病毒（VACV），用于根除天花的疫苗，编码一种称为C16的蛋白质，该蛋白质与DNA-PK复合物结合，并阻止其感应外源DNA并激活免疫反应。缺乏C16的VACV株表现出降低的毒力，并且与此一致，宿主对感染产生了更强的先天免疫应答。这说明了DNA-PK作为外源DNA传感器的重要性，并增加了对VACV与宿主之间相互作用的理解。它还说明了病原体毒力因子的研究如何导致免疫系统新成分的鉴定。
The innate immune system is critical in the response to infection by pathogens and it is activated by pattern recognition receptors (PRRs) binding to pathogen associated molecular patterns (PAMPs). During viral infection, the direct recognition of the viral nucleic acids, such as the genomes of DNA viruses, is very important for activation of innate immunity. Recently, DNA-dependent protein kinase (DNA-PK), a heterotrimeric complex consisting of the Ku70/Ku80 heterodimer and the catalytic subunit DNA-PKcs was identified as a cytoplasmic PRR for DNA that is important for the innate immune response to intracellular DNA and DNA virus infection. Here we show that vaccinia virus (VACV) has evolved to inhibit this function of DNA-PK by expression of a highly conserved protein called C16, which was known to contribute to virulence but by an unknown mechanism. Data presented show that C16 binds directly to the Ku heterodimer and thereby inhibits the innate immune response to DNA in fibroblasts, characterised by the decreased production of cytokines and chemokines. Mechanistically, C16 acts by blocking DNA-PK binding to DNA, which correlates with reduced DNA-PK-dependent DNA sensing. The C-terminal region of C16 is sufficient for binding Ku and this activity is conserved in the variola virus (VARV) orthologue of C16. In contrast, deletion of 5 amino acids in this domain is enough to knockout this function from the attenuated vaccine strain modified vaccinia virus Ankara (MVA). In vivo a VACV mutant lacking C16 induced higher levels of cytokines and chemokines early after infection compared to control viruses, confirming the role of this virulence factor in attenuating the innate immune response. Overall this study describes the inhibition of DNA-PK-dependent DNA sensing by a poxvirus protein, adding to the evidence that DNA-PK is a critical component of innate immunity to DNA viruses. To mount an immune response to an invading bacterium or virus (pathogens), the host must detect foreign molecules from the pathogen. Pathogens have conserved features called pathogen associated molecular patterns (PAMPs) that are distinct from host cells and which are recognised by the host using specific sensors (called pattern recognition receptors, PRRs). One example of a PAMP is DNA in the cytoplasm. Cytoplasmic DNA activates the innate immune system, but the PRRs responsible remain incompletely understood. One such PRR, DNA-PK, was identified recently. Here we demonstrate that vaccinia virus (VACV), the vaccine used to eradicate smallpox, encodes a protein called C16 which binds to the DNA-PK complex and prevents it from sensing foreign DNA and activating the immune response. A VACV strain lacking C16 showed reduced virulence and, consistent with this, the host mounted a stronger innate immune response to infection. This illustrates the importance of DNA-PK as a sensor for foreign DNA, and increases understanding of the interaction between VACV and the host. It also illustrates how the study of virulence factors of pathogens can lead to the identification of novel components of the immune system.
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影响因子：
64.8
作者：
通讯作者：
--
DOI：
10.1126/science.1183173
发表时间：
2010-02-12
期刊：
Science (New York, N.Y.)
影响因子：
--
作者：
Doceul V;Hollinshead M;van der Linden L;Smith GL
通讯作者：
Smith GL
影响因子：
30.5
作者：
Buerckstuemmer, Tilmann;Baumann, Christoph;Superti-Furga, Giulio
通讯作者：
Superti-Furga, Giulio
影响因子：
30.5
作者：
通讯作者：
--
影响因子：
6.7
作者：
Bahar, Mohammad W.;Kenyon, Julia C.;Grimes, Jonathan M.
通讯作者：
Grimes, Jonathan M.