Cytosolic virus detection in Caenorhabditis elegans

描述(申请人提供)：在哺乳动物中，包括人类，RIG-I样RNA解旋酶(RIG-I)RIG-I、MDA5和LGP2检测入侵的病毒RNA，从而启动抗病毒信号级联反应。有趣的是，尽管RIG-I和MDA5具有相似的结构域结构，但它们似乎检测到不同类别的RNA病毒。LGP2是另一种类型的RLH，它缺乏RIG-I和MDA5中保守的N-末端结构域，并在RIG-I和MDA5启动的抗病毒信号转导中发挥调节作用。目前，RIG-I和MDA5是否识别更多的病毒分子模式以用于RIG-I有效的病毒检测，以及是什么决定了RIG-I和MDA5的病毒识别特异性在很大程度上尚不清楚。由于目前对LGP2的功能和机制的研究一直存在争议，因此，LGP2如何调控RIG-I和MDA5启动的抗病毒信号仍不清楚。我们最近的观察表明，作为一个三人家族，RLHs在线虫抗病毒RNA沉默中也发挥着重要作用。最重要的是，一种被称为DRH-1的蠕虫RLH似乎以类似于RIG-I检测病毒的方式对病毒检测做出贡献。我们的研究也清楚地表明，DRH-3，另一种与DRH-1结构相似的线虫RLH，在抗病毒RNA沉默中发挥着独特的作用。第三个线虫RLH被称为DRH-2，它缺乏DRH-1和DRH-3中的N-末端结构域，并被认为对抗病毒RNA沉默具有负面调节作用。有趣的是，DRH-2在功能上取代了DRH-1的相应结构域，表明它可能特异性地调节DRH-1在抗病毒RNA沉默中的功能。综上所述，这些观察结果建立了线虫作为在整个生物体水平上研究RLH介导的病毒传感的理想模型系统。为了更好地了解抗病毒RNA沉默是如何在线虫中检测到病毒并将其摧毁的，我们建议(1)通过研究DRH-1检测到什么以及抗病毒信号如何被传递到下游信号分子来阐明DRH-1在病毒感知中的机制；(2)通过定义DRH-3在抗病毒沉默和病毒致病中的作用来阐明控制DRH-1和DRH-3功能特异性的机制；(3)确定DRH-2是否专门针对和调节DRH-1的功能。拟议的研究结果还有望：(1)确定RIG-I和MDA5识别的新的分子模式；(2)阐明RIG-I和MDA5控制病毒识别特异性的机制；(3)直接投入到LGP2介导的由RIG-I和MDA5启动的抗病毒信号调节的研究中。

DESCRIPTION (provided by applicant): In mammals, including humans, RIG-I-like RNA helicases (RLHs) RIG-I, MDA5 and LGP2 detect invading viral RNAs thereby to initiate an antiviral signaling cascade. Interestingly, although sharing similar domain structure, RIG-I and MDA5 appear to detect RNA viruses of distinct classes. LGP2 is another type of RLH that lacks the N-terminal domains conserved in RIG-I and MDA5 and is known to play a regulatory role in antiviral signaling initiated by RIG-I and MDA5. Currently, whether additional viral molecular patterns are recognized by RIG-I and MDA5 for efficient virus detection by RIG-I and what determines the virus recognition specificity of RIG-I and MDA5 remain largely unknown. Since current studies on the function and mechanism of LGP2 have been generating controversial findings, as a result, how LGP2 regulates the antiviral signaling initiated by RIG-I and MDA5 remains unclear. Our recent observations suggested that RLHs as a three-member family also play important role in antiviral RNA silencing in the nematode Caenorhabditis elegans. Most importantly, one of the worm RLHs, termed DRH-1, appears to contribute to virus detection in a way similar to virus detection by RIG-I. It was also clear from our study that DRH-3, another C. elegans RLH that shares similar domain structure with DRH-1, plays a distinct role in antiviral RNA silencing. The third C. elegans RLH, termed DRH-2, lacks an N-terminal domain found in DRH-1 and DRH-3 and is known to negatively regulate antiviral RNA silencing. Interestingly, DRH-2 functionally replaces the corresponding domains of DRH-1, suggesting that it may specifically regulate the function of DRH-1 in antiviral RNA silencing. Taken together, these observations together establish C. elegans as an ideal model system to study RLH-mediated virus sensing at whole organism level. To better understand how viruses are detected and destroyed by antiviral RNA silencing in C. elegans, here we propose to (1) elucidate the mechanism of DRH-1 in virus sensing by investigating what DRH-1 detects and how the antiviral signal is transmitted to downstream signaling molecules; (2) elucidate the mechanism controlling the function specificity of DRH-1 and DRH-3 by defining a role of DRH-3 in antiviral silencing and viral pathogenesis; (3) determine if DRH-2 specifically targets and regulates the function of DRH-1. Findings from the proposed studies are also expected to (1) identify novel molecular patterns recognized by RIG-I and MDA5; (2) shed light on the mechanism controlling virus recognition specificity of RIG-I and MDA5; (3) have direct input to input to the study of LGP2-mediated regulation of antiviral signaling initiated by RIG-I and MDA5.