Cytosolic virus detection in Caenorhabditis elegans

描述（由申请人提供）：在包括人类在内的哺乳动物中，RIG-I样RNA解解酶（RLHs） RIG-I、MDA5和LGP2检测入侵的病毒RNA，从而启动抗病毒信号级联。有趣的是，尽管共享相似的结构域结构，rig - 1和MDA5似乎检测不同类别的RNA病毒。LGP2是另一种RLH类型，缺乏rig - 1和MDA5中保守的n端结构域，已知在rig - 1和MDA5启动的抗病毒信号传导中起调节作用。目前，RIG-I和MDA5是否能够识别额外的病毒分子模式，从而有效地检测RIG-I病毒，以及是什么决定了RIG-I和MDA5的病毒识别特异性，在很大程度上仍然未知。由于目前对LGP2的功能和机制的研究一直存在争议，因此LGP2如何调节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，RLHs作为一个三成员家族也在秀丽隐杆线虫的抗病毒RNA沉默中发挥重要作用。最重要的是，其中一种被称为DRH-1的蠕虫RLHs似乎以类似于rig -1的方式对病毒检测做出了贡献。我们的研究还清楚地表明，与DRH-1具有相似结构域的另一种秀丽隐杆线虫RLH DRH-3在抗病毒RNA沉默中发挥着独特的作用。第三种秀丽隐杆线虫RLH，称为DRH-2，缺乏DRH-1和DRH-3中发现的n端结构域，并且已知负调控抗病毒RNA沉默。有趣的是，DRH-2在功能上取代了DRH-1的相应结构域，这表明它可能特异性调节DRH-1在抗病毒RNA沉默中的功能。综上所述，这些观察结果共同建立了秀丽隐杆线虫作为研究rlh介导的病毒在整个生物体水平上感知的理想模型系统。为了更好地了解秀丽隐杆线虫中抗病毒RNA沉默如何检测和破坏病毒，我们提出：(1)通过研究DRH-1检测什么以及抗病毒信号如何传递给下游信号分子来阐明DRH-1在病毒感知中的机制；(2)通过明确DRH-3在抗病毒沉默和病毒发病机制中的作用，阐明DRH-1和DRH-3的功能特异性调控机制；(3)确定DRH-2是否特异性靶向并调控DRH-1的功能。拟议研究的结果也有望(1)确定rig - 1和MDA5识别的新分子模式；(2)揭示了rig - 1和MDA5病毒识别特异性的调控机制；(3)直接参与研究lgp2介导的RIG-I和MDA5启动的抗病毒信号调控。

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.