Disruption of TLR3 signaling due to cleavage of TRIF by the hepatitis A virus protease-polymerase processing intermediate, 3CD.
Disruption of TLR3 signaling due to cleavage of TRIF by the hepatitis A virus protease-polymerase processing intermediate, 3CD.
复制标题
DOI：
10.1371/journal.ppat.1002169
复制
发表时间：
2011-09
期刊：
影响因子：
6.7
通讯作者：
Lemon SM
中科院分区：
文献类型：
--
作者：
Qu L;Feng Z;Yamane D;Liang Y;Lanford RE;Li K;Lemon SM
Toll 样受体 3 (TLR3) 和胞质 RIG-I 样解旋酶（RIG-I 和 MDA5）感知病毒 RNA 并激活先天免疫信号通路，分别通过特定的接头蛋白、包含 TIR 结构域的接头诱导干扰素-β (TRIF) 和线粒体抗病毒信号蛋白 (MAVS) 诱导干扰素 (IFN) 的表达。此前，我们证明甲型肝炎病毒（HAV）是一种独特的亲肝性人类小核糖核酸病毒，通过以 MAVS 为目标，被 3ABC 裂解，从而破坏 RIG-I/MDA5 信号传导。3ABC 是唯一的 HAV 蛋白酶 3Cpro 的前体，3Cpro 是通过病毒多蛋白 P3 (3ABCD) 片段的自动加工而衍生的。在这里，我们发现 HAV 还破坏 TLR3 信号传导，通过靶向 TRIF 被独特的 3ABCD 加工中间体（3CD 蛋白酶聚合酶前体）降解，抑制聚（I:C）刺激的 IFN 调节因子 3 (IRF-3) 二聚化、IRF-3 易位到细胞核以及 IFN-β 启动子激活。 TRIF 可被 3CD 蛋白水解裂解，但不会被成熟的 3Cpro 蛋白酶或降解 MAVS 的 3ABC 前体裂解。 3CD 介导的 TRIF 降解取决于 3Cpro 和下游 3Dpol 序列的半胱氨酸蛋白酶活性，但不取决于 3Dpol 聚合酶活性。切割发生在 TRIF 中的两个非规范 3Cpro 识别序列处，并涉及一个分层过程，其中 Gln-554 处的初级切割是 Gln-190 处断裂的先决条件。突变研究的结果表明，当 3Dpol 序列与 3CD 中的顺式融合时，3Dpol 序列可调节上游 3Cpro 蛋白酶的底物特异性，从而使 3CD 能够靶向 3Cpro 通常不识别的切割位点。因此，HAV 通过由源自常见 3ABCD 多蛋白加工中间体的两种不同的蛋白酶前体裂解必需的接头蛋白，从而破坏 RIG-I/MDA5 和 TLR3 信号传导途径。虽然针对肝脏的病毒通常会导致长期感染并具有相当高的发病率，但人们对它们如何逃避宿主反应的了解有限。我们研究了甲型肝炎病毒（HAV），它是人类急性肝炎的重要原因。虽然 HAV 感染通常会导致肝脏炎症，但尽管病毒复制旺盛，但在感染的最初几周内，肝脏并没有出现疾病。这表明 HAV 要么无法刺激宿主先天免疫传感器，要么有效逃避宿主先天免疫传感器的识别。我们之前的工作表明，HAV 通过靶向 MAVS（一种必需的衔接蛋白）来破坏 RIG-I/MDA5 信号传导，并被 3ABC（唯一的 HAV 蛋白酶 3Cpro 的前体）降解。在这里，我们展示了一种独特的病毒加工中间体，3CD 蛋白酶聚合酶，通过降解其接头蛋白 TRIF 来破坏 TLR3 信号传导。 HAV 已经发展出一种新策略，用单一蛋白酶靶向两种不同的宿主衔接蛋白，使用其 3Dpol RNA 聚合酶在与 3CD 前体融合时修改其 3Cpro 蛋白酶的底物特异性，从而使其能够靶向 TRIF 中的非规范 3Cpro 识别序列。这个病毒适应的显着例子使得病毒能够用一种病毒蛋白酶靶向两种不同的宿主衔接蛋白。
Toll-like receptor 3 (TLR3) and cytosolic RIG-I-like helicases (RIG-I and MDA5) sense viral RNAs and activate innate immune signaling pathways that induce expression of interferon (IFN) through specific adaptor proteins, TIR domain-containing adaptor inducing interferon-β (TRIF), and mitochondrial antiviral signaling protein (MAVS), respectively. Previously, we demonstrated that hepatitis A virus (HAV), a unique hepatotropic human picornavirus, disrupts RIG-I/MDA5 signaling by targeting MAVS for cleavage by 3ABC, a precursor of the sole HAV protease, 3Cpro, that is derived by auto-processing of the P3 (3ABCD) segment of the viral polyprotein. Here, we show that HAV also disrupts TLR3 signaling, inhibiting poly(I:C)-stimulated dimerization of IFN regulatory factor 3 (IRF-3), IRF-3 translocation to the nucleus, and IFN-β promoter activation, by targeting TRIF for degradation by a distinct 3ABCD processing intermediate, the 3CD protease-polymerase precursor. TRIF is proteolytically cleaved by 3CD, but not by the mature 3Cpro protease or the 3ABC precursor that degrades MAVS. 3CD-mediated degradation of TRIF depends on both the cysteine protease activity of 3Cpro and downstream 3Dpol sequence, but not 3Dpol polymerase activity. Cleavage occurs at two non-canonical 3Cpro recognition sequences in TRIF, and involves a hierarchical process in which primary cleavage at Gln-554 is a prerequisite for scission at Gln-190. The results of mutational studies indicate that 3Dpol sequence modulates the substrate specificity of the upstream 3Cpro protease when fused to it in cis in 3CD, allowing 3CD to target cleavage sites not normally recognized by 3Cpro. HAV thus disrupts both RIG-I/MDA5 and TLR3 signaling pathways through cleavage of essential adaptor proteins by two distinct protease precursors derived from the common 3ABCD polyprotein processing intermediate. While viruses that target the liver often cause lengthy infections with considerable morbidity, there is limited understanding of how they evade host responses. We have studied hepatitis A virus (HAV), an important cause of acute hepatitis in humans. Although HAV infection typically results in hepatic inflammation, there is no disease in the liver during the first weeks of infection despite robust virus replication. This suggests that HAV either fails to stimulate or efficiently evades recognition by host innate immune sensors. Our prior work showed HAV disrupts RIG-I/MDA5 signaling by targeting MAVS, an essential adaptor protein, for degradation by 3ABC, a precursor of the only HAV protease, 3Cpro. Here, we show here that a distinct viral processing intermediate, the 3CD protease-polymerase, disrupts TLR3 signaling by degrading its adaptor protein, TRIF. HAV has evolved a novel strategy to target two different host adaptor proteins with a single protease, using its 3Dpol RNA polymerase to modify the substrate specificity of its 3Cpro protease when fused to it in the 3CD precursor, thus allowing it to target non-canonical 3Cpro recognition sequences in TRIF. This remarkable example of viral adaptation allows the virus to target two different host adaptor proteins with a single viral protease.
登录
查看更多内容
影响因子：
64.8
作者：
ALLAIRE, M;CHERNAIA, MM;JAMES, MNG
通讯作者：
JAMES, MNG
影响因子：
4.4
作者：
Kaiser, WJ;Offermann, MK
通讯作者：
Offermann, MK
影响因子：
64.8
作者：
Meylan, E;Curran, J;Tschopp, R
通讯作者：
Tschopp, R
影响因子：
13.5
作者：
Martin, A;Lemon, SM
通讯作者：
Lemon, SM
影响因子：
3.7
作者：
Losick, VP;Schlax, PE;Lawson, TG
通讯作者：
Lawson, TG