Functional specialization of the small interfering RNA pathway in response to virus infection.
Functional specialization of the small interfering RNA pathway in response to virus infection.
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DOI：
10.1371/journal.ppat.1003579
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发表时间：
2013
期刊：
影响因子：
6.7
通讯作者：
Carthew RW
中科院分区：
文献类型：
--
作者：
Marques JT;Wang JP;Wang X;de Oliveira KP;Gao C;Aguiar ER;Jafari N;Carthew RW
在果蝇中，当外源性或内源性双链RNA（dsRNA）被Dicer-2（Dcr-2）加工成小干扰RNA（siRNAs）时，转录后基因沉默发生，所述Dicer-2与称为Loquacious（Loqs-PD）的dsRNA结合蛋白（dsRBP）辅因子结合。然后通过Dcr-2与另一种称为R2D2的dsRBP辅因子的作用将siRNA加载到Argonaute-2（Ago 2）上。加载的Ago 2执行与siRNA具有序列互补性的靶RNA的破坏。尽管Dcr-2、R2D2和Ago 2是先天性抗病毒防御所必需的，但病毒衍生的siRNA（vsiRNA）生物合成和病毒靶点抑制的机制仍不清楚。在这里，我们的特点的反应机制介导的siRNA对两种不同的RNA病毒感染果蝇。在这两种情况下，我们表明vsiRNA是由病毒基因组复制过程中形成的dsRNA的Dcr-2加工产生的，并且在较小程度上是病毒转录。这些vsiRNA似乎优先靶向病毒聚腺苷酸化RNA以抑制病毒复制。与其在沉默内源性靶标中的作用相反，Loqs-PD完全用于沉默病毒。vsiRNA的生物发生不依赖于Loqs-PD和R2D2。然而，R2D2是分选和加载vsiRNA到Ago 2上以及抑制病毒RNA表达所必需的。将病毒RNA直接注射到果蝇中导致复制，其也不依赖于Loqs-PD。这表明抗病毒途径的触发与病毒进入模式无关，但与病毒RNA内在特征的识别有关。我们的研究结果表明，存在一个vsiRNA途径，这是独立于内源性siRNA途径，是由病毒RNA特异性触发。我们推测，这种独特的框架可能是必要的一个迅速和有效的抗病毒反应。RNA干扰（RNAi）途径利用小的非编码RNA来沉默基因表达。在昆虫中，RNAi调节内源基因并作为基于RNA的免疫系统对抗病毒感染。在这里，我们揭示了RNA病毒如何触发RNAi的细节。作为复制中间体或由RNA病毒转录产生的双链RNA（dsRNA）可用作病毒衍生的小干扰RNA（vsiRNA）的生物发生的底物。与其他dsRNA不同，病毒RNA加工涉及Dicer，但不涉及其典型伴侣蛋白Loqs-PD。因此，vsiRNA生物发生在机制上不同于内源性siRNA或衍生自其他外源性RNA来源的siRNA的生物发生。我们的研究结果表明，与其他类型的RNAi沉默相比，专门用于RNA病毒沉默的途径具有特殊性。对病毒感染过程中RNAi机制的理解可能对控制虫媒病毒和使用siRNA治疗人类病毒感染具有意义。
In Drosophila, post-transcriptional gene silencing occurs when exogenous or endogenous double stranded RNA (dsRNA) is processed into small interfering RNAs (siRNAs) by Dicer-2 (Dcr-2) in association with a dsRNA-binding protein (dsRBP) cofactor called Loquacious (Loqs-PD). siRNAs are then loaded onto Argonaute-2 (Ago2) by the action of Dcr-2 with another dsRBP cofactor called R2D2. Loaded Ago2 executes the destruction of target RNAs that have sequence complementarity to siRNAs. Although Dcr-2, R2D2, and Ago2 are essential for innate antiviral defense, the mechanism of virus-derived siRNA (vsiRNA) biogenesis and viral target inhibition remains unclear. Here, we characterize the response mechanism mediated by siRNAs against two different RNA viruses that infect Drosophila. In both cases, we show that vsiRNAs are generated by Dcr-2 processing of dsRNA formed during viral genome replication and, to a lesser extent, viral transcription. These vsiRNAs seem to preferentially target viral polyadenylated RNA to inhibit viral replication. Loqs-PD is completely dispensable for silencing of the viruses, in contrast to its role in silencing endogenous targets. Biogenesis of vsiRNAs is independent of both Loqs-PD and R2D2. R2D2, however, is required for sorting and loading of vsiRNAs onto Ago2 and inhibition of viral RNA expression. Direct injection of viral RNA into Drosophila results in replication that is also independent of Loqs-PD. This suggests that triggering of the antiviral pathway is not related to viral mode of entry but recognition of intrinsic features of virus RNA. Our results indicate the existence of a vsiRNA pathway that is separate from the endogenous siRNA pathway and is specifically triggered by virus RNA. We speculate that this unique framework might be necessary for a prompt and efficient antiviral response. The RNA interference (RNAi) pathway utilizes small non-coding RNAs to silence gene expression. In insects, RNAi regulates endogenous genes and functions as an RNA-based immune system against viral infection. Here we have uncovered details of how RNAi is triggered by RNA viruses. Double-stranded RNA (dsRNA) generated as a replication intermediate or from transcription of the RNA virus can be used as substrate for the biogenesis of virus-derived small interfering RNAs (vsiRNAs). Unlike other dsRNAs, virus RNA processing involves Dicer but not its canonical partner protein Loqs-PD. Thus, vsiRNA biogenesis is mechanistically different from biogenesis of endogenous siRNAs or siRNAs derived from other exogenous RNA sources. Our results suggest a specialization of the pathway dedicated to silencing of RNA viruses versus other types of RNAi silencing. The understanding of RNAi mechanisms during viral infection could have implications for the control of insect-borne viruses and the use of siRNAs to treat viral infections in humans.
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DOI：
10.1073/pnas.0813412106
发表时间：
2009-03-31
影响因子：
11.1
作者：
Flynt, Alex;Liu, Na;Lai, Eric C.
通讯作者：
Lai, Eric C.
影响因子：
16.8
作者：
Haley, B;Zamore, PD
通讯作者：
Zamore, PD
影响因子：
3.1
作者：
Jose J;Snyder JE;Kuhn RJ
通讯作者：
Kuhn RJ
影响因子：
16
作者：
Cenik ES;Fukunaga R;Lu G;Dutcher R;Wang Y;Tanaka Hall TM;Zamore PD
通讯作者：
Zamore PD
影响因子：
30.3
作者：
Aliyari, Roghiyh;Wu, Qingfa;Li, Hong-Wei;Wang, Xiao-Hong;Li, Feng;Green, Lance D.;Han, Cliff S.;Li, Wan-Xiang;Ding, Shou-Wei
通讯作者：
Ding, Shou-Wei