A structural basis for discriminating between self and nonself double-stranded RNAs in mammalian cells
A structural basis for discriminating between self and nonself double-stranded RNAs in mammalian cells
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DOI：
10.1038/nbt1205
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发表时间：
2006-05-01
影响因子：
46.9
通讯作者：
Williams, BRG
中科院分区：
文献类型：
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作者：
Marques, JT;Devosse, T;Williams, BRG
由小干扰RNA（siRNA）触发的非特异性效应使RNA干扰（RNAi）用于特异性下调基因表达的用途复杂化（1-5）。为了揭示这些非特异性活动的基础，我们分析了化学合成的siRNA对哺乳动物双链RNA（dsRNA）激活的信号通路的影响。长度范围为21至27个核苷酸（nt）的siRNA在它们缺乏2-nt 3'突出端（Dicer产物的特征）时激活干扰素系统。我们发现siRNA的识别是由RNA解旋酶RIG-I介导的，并且3'突出端的存在损害了其解旋dsRNA底物并激活转录因子IRF-3的下游信号传导的能力。这些结果提示了区分作为内源性Dicer产物的microRNA和非自身dsRNA（例如病毒复制的副产物）的结构基础。这些发现将使siRNA的合理设计能够避免非特异性效应，或者诱导旁观者效应，从而潜在地增加基于siRNA的病毒感染或癌症治疗的功效。
Nonspecific effects triggered by small interfering RNAs (siRNAs) complicate the use of RNA interference (RNAi) to specifically downregulate gene expression(1-5). To uncover the basis of these nonspecific activities, we analyzed the effect of chemically synthesized siRNAs on mammalian double-stranded RNA (dsRNA)-activated signaling pathways. siRNAs ranging from 21 to 27 nucleotides (nt) in length activated the interferon system when they lacked 2-nt 3' overhangs, a characteristic of Dicer products. We show that the recognition of siRNAs is mediated by the RNA helicase RIG-I and that the presence of 3' overhangs impairs its ability to unwind the dsRNA substrate and activate downstream signaling to the transcription factor IRF-3. These results suggest a structural basis for discrimination between microRNAs that are endogenous Dicer products, and nonself dsRNAs such as by-products of viral replication. These findings will enable the rational design of siRNAs that avoid nonspecific effects or, alternatively, that induce bystander effects to potentially increase the efficacy of siRNA-based treatments of viral infections or cancer.