Physiological Function of Virus-induced sigraing for Artivirall mate immunity

I型干扰素（IFN）在抗病毒先天免疫中起关键作用。病毒感染的细胞短暂表达I型IFN，并通过IFN受体介导的信号传导向周围细胞传递强抗病毒活性。在本研究中，我们重点研究了病毒传感器分子RIG-I家族RNA解旋酶的功能，RIG-I家族RNA解旋酶检测细胞质中的病毒RNA，诱导IFN基因表达，并分析了RIG-I家族介导的抗病毒先天免疫激活的分子机制。我们分析了病毒诱导的III型ifn的激活。我们的数据清楚地表明，III型ifn和I型ifn一样受到rig -I介导的信号传导的调节。为了阐明另一个RIG-I家族成员MDA5的生理意义，我们与大阪大学Shizuo Akira博士的团队合作，产生并分析了MDA5基因敲除小鼠。结果表明，MDA5在病毒诱导的IFN基因激活中也起着重要作用。然而，MDA5参与了包括小核糖核酸病毒在内的不同类型病毒的检测。我们试图为rig - i介导的信号转导生成一种新的检测系统。rig - 1 n端CARD的强制寡聚化明显激活了与自然病毒诱导的信号相同的信号。利用该系统，我们将观察rig - 1介导的信号在先天免疫中的生理意义。我们使用体外检测系统分析rig - 1的底物特异性。最后，我们发现RIG-I不仅可以检测含有5pp的单链RNA，还可以检测含有单磷酸盐的双链RNA。此外，RIG-I的c端结构域对于检测这些底物以启动抗病毒信号传导至关重要。

Type I interferon (IFN) plays a critical role in antiviral innate immunity. Virus-infected cells transiently express type I IFNs and confer strong antiviral activities on surrounding cells Via IFN receptor-mediated signaling. In this research, we focused on the function of virus sensor molecules, RIG-I family RNA helicases, which detect viral RNA in cytoplasm to induce IFN gene expression, and analyzed molecular mechanisms underlying activation of RIG-I family-mediated antiviral innate immunity.1. We analyzed virus-induced activation of type III IFNs. Our data clearly indicated that type III IFNs are regulated by RIG-I-mediated signaling as well as type I IFNs.2. In order to elucidate a physiological significance of another RIG-I family member, MDA5, we generated and analyzed knockout mice of MDA5 gene, as collaboration with Dr. Shizuo Akira's group in Osaka University. The results showed that MDA5 also plays an essential role in virus-induced activation of IFN genes. However, MDA5 were involved in the detection of different type of viruses including picorna viruses.3. We tried to generate a novel assay system for RIG-I-mediated signal transduction. The enforced oligomerization of N-terminal CARD of RIG-I clearly activated the identical signaling to natural virus-induced signal. Using this system, we are going to observe the physiological significance of RIG-I- mediated signaling in innate immunity.4. We analyzed substrate specificity of RIG-I using in vitro assay system. Finally, we identified RIG-I can detect not only 5ppp-dontaining singe stranded RNA but also monophosphate-containing double stranded RNAs. Furthermore, the C-terminal domain of RIG-I was essential for detection of these substrates to initiate antiviral signaling.