Specific Inhibition of the PKR-Mediated Antiviral Response by the Murine Cytomegalovirus Proteins m142 and m143
Specific Inhibition of the PKR-Mediated Antiviral Response by the Murine Cytomegalovirus Proteins m142 and m143
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DOI：
10.1128/jvi.01558-08
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发表时间：
2009-02-01
影响因子：
5.4
通讯作者：
Brune, Wolfram
中科院分区：
文献类型：
--
作者：
Budt, Matthias;Niederstadt, Lars;Brune, Wolfram
在病毒感染期间产生的双链RNA（dsRNA）激活几种细胞抗病毒反应。其中最具特征的是阻断由dsRNA依赖性蛋白激酶（PKR）和寡腺苷酸合成酶（OAS）/RNase L系统介导的蛋白质合成。由于病毒复制依赖于蛋白质合成，许多病毒已经进化出抵消PKR和OAS/RNase L途径的机制。鼠巨细胞病毒（MCMV）蛋白m142和m143已被表征为抑制PKR活化、翻译起始因子eIF 2 α的磷酸化和随后的蛋白质合成关闭的dsRNA结合蛋白。在本研究中，我们分析了PKR和OAS依赖性途径在存在或不存在m142和m143的情况下对MCMV复制控制的贡献。我们发现，在感染m142和m143缺陷MCMV期间，诱导eIF 2 α磷酸化是由PKR特异性介导的，而不是由相关的eIF 2 α激酶PERK或GCN 2介导的。痘苗病毒（E3 L）或单纯疱疹病毒（γ 34.5）的PKR拮抗剂挽救了m142和m143缺失的MCMV株的复制缺陷。此外，m142和m143相互结合并与PKR相互作用。相比之下，在存在或不存在m142和m143的情况下，未检测到MCMV对OAS/RNase L途径的激活，表明这些病毒蛋白对该途径的影响很小或没有影响。一致地，m142和m143缺陷MCMV株在缺乏PKR的成纤维细胞中复制到高滴度，但在缺乏RNase L的细胞中不复制。因此，PKR介导的抗病毒应答是m142和m143的重要性的原因。
Double-stranded RNA (dsRNA) produced during viral infection activates several cellular antiviral responses. Among the best characterized is the shutoff of protein synthesis mediated by the dsRNA-dependent protein kinase (PKR) and the oligoadenylate synthetase (OAS)/RNase L system. As viral replication depends on protein synthesis, many viruses have evolved mechanisms for counteracting the PKR and OAS/RNase L pathways. The murine cytomegalovirus (MCMV) proteins m142 and m143 have been characterized as dsRNA binding proteins that inhibit PKR activation, phosphorylation of the translation initiation factor eIF2 alpha, and a subsequent protein synthesis shutoff. In the present study we analyzed the contribution of the PKR- and the OAS-dependent pathways to the control of MCMV replication in the absence or presence of m142 and m143. We show that the induction of eIF2 alpha phosphorylation during infection with an m142- and m143-deficient MCMV is specifically mediated by PKR, not by the related eIF2 alpha kinases PERK or GCN2. PKR antagonists of vaccinia virus (E3L) or herpes simplex virus (gamma 34.5) rescued the replication defect of an MCMV strain with deletions of both m142 and m143. Moreover, m142 and m143 bound to each other and interacted with PKR. By contrast, an activation of the OAS/RNase L pathway by MCMV was not detected in the presence or absence of m142 and m143, suggesting that these viral proteins have little or no influence on this pathway. Consistently, an m142- and m143-deficient MCMV strain replicated to high titers in fibroblasts lacking PKR but did not replicate in cells lacking RNase L. Hence, the PKR- mediated antiviral response is responsible for the essentiality of m142 and m143.