Immunity and Pathogenesis Program, Infectious and Inflammatory Disease Center, Sanford Burnham Prebys Medical Discovery Institute, 10901 North Torrey Pines Road, La Jolla, California 92037, USA.
The San Diego Center for Systems Biology (SDCSB), La Jolla, California 92093, USA.
Nat Microbiol. 2017 Mar 1;2:17022. doi: 10.1038/nmicrobiol.2017.22.
Retinoic acid-inducible gene I (RIG-I) receptor recognizes 5'-triphosphorylated RNA and triggers a signalling cascade that results in the induction of type-I interferon (IFN)-dependent responses. Its precise regulation represents a pivotal balance between antiviral defences and autoimmunity. To elucidate the cellular cofactors that regulate RIG-I signalling, we performed two global RNA interference analyses to identify both positive and negative regulatory nodes operating on the signalling pathway during virus infection. These factors were integrated with experimentally and computationally derived interactome data to build a RIG-I protein interaction network. Our analysis revealed diverse cellular processes, including the unfolded protein response, Wnt signalling and RNA metabolism, as critical cellular components governing innate responses to non-self RNA species. Importantly, we identified K-Homology Splicing Regulatory Protein (KHSRP) as a negative regulator of this pathway. We find that KHSRP associates with the regulatory domain of RIG-I to maintain the receptor in an inactive state and attenuate its sensing of viral RNA (vRNA). Consistent with increased RIG-I antiviral signalling in the absence of KHSRP, viral replication is reduced when KHSRP expression is knocked down both in vitro and in vivo. Taken together, these data indicate that KHSRP functions as a checkpoint regulator of the innate immune response to pathogen challenge.
视黄酸诱导基因 I（RIG-I）受体识别 5'-三磷酸化 RNA，并触发信号级联反应，导致 I 型干扰素（IFN）依赖性反应的诱导。其精确调节代表了抗病毒防御和自身免疫之间的关键平衡。为了阐明调节 RIG-I 信号的细胞共因子，我们进行了两次全局 RNA 干扰分析，以鉴定在病毒感染过程中作用于信号通路的正向和负向调节节点。这些因子与实验和计算衍生的互作组数据相结合，构建了 RIG-I 蛋白相互作用网络。我们的分析揭示了多种细胞过程，包括未折叠蛋白反应、Wnt 信号和 RNA 代谢，作为控制先天对非自身 RNA 种类反应的关键细胞成分。重要的是，我们确定 K-Homology Splicing Regulatory Protein (KHSRP) 是该通路的负调节剂。我们发现 KHSRP 与 RIG-I 的调节域结合，使受体处于非活跃状态，并减弱其对病毒 RNA（vRNA）的感应。与 KHSRP 缺失时 RIG-I 的抗病毒信号增强一致，当体外和体内敲低 KHSRP 表达时，病毒复制减少。总之，这些数据表明 KHSRP 作为先天免疫反应对病原体挑战的检查点调节剂发挥作用。
