凡纳滨对虾Vago信号通路的调控机制及其在抗病毒免疫中的作用

Vago is a novel identified antiviral cytokine in Arthropoda and has been considered to be functionally similar to vertebrate interferon (IFN), which needs to be evidenced. Viral nucleic acids can induce expression of Vago, but the exact mechanism is still unclear. Vago can play an antiviral role through activating the JAK/STAT pathway with the underlying mechanism being unknown. We have found an interferon regulatory factor (IRF) in Pacific White Shrimp, Litopenaeus vannamei, and found an interferon-stimulated response element (ISRE) in the promoter of Litopenaeus vannamei Vago gene, suggesting that the expression of Vago could be regulated by IRF. In this project, using Litopenaeus vannamei as the research object, we plan to study the signaling pathway through which IRF regulates the expression of Vago, and to identify the receptor of Vago and further to study the mechanism by which Vago regulates the JAK/STAT pathway. These could reveal the regulatory mechanism of the Vago signaling pathway that centers on the IRF-Vago-JAK/STAT axis in shrimp. Furthermore, we plan to study the interaction of the Vago pathway with other immune signaling pathways and its roles in the shrimp antiviral immunity and to analyze its evolutionary status through comparing with the vertebrate IFN pathway. This research could provide an in-depth insight into the antiviral mechanism of shrimp to make a theoretical foundation for preventing diseases, and could offer a chance to answer the scientific question whether invertebrates have an interferon-like pathway.

Vago是新发现的节肢动物抗病毒细胞因子，被认为与脊椎动物干扰素（IFN）功能相似，但此观点亟需证实。病毒核酸可诱导Vago的表达，但其信号通路不明确；Vago能够通过激活JAK/STAT通路发挥抗病毒作用，但其机制尚不清楚。我们发现了对虾的IFN调节因子（IRF）,在Vago启动子中发现了IFN激活反应元件，表明Vago的表达可能受到IRF的调控。本项目拟以凡纳滨对虾为对象，研究IRF调控Vago表达的信号通路，鉴定Vago的受体并研究Vago调控JAK/STAT通路的机制，从而揭示对虾以IRF-Vago-JAK/STAT为中心的Vago信号通路的调控机制；进一步研究该通路与其它通路的互作及其在抗病毒免疫中的作用，并与脊椎动物IFN通路进行比较，解析其进化地位。本研究有助于深入了解对虾抗病毒机理为疾病防治提供理论基础，并可为无脊椎动物中是否存在类似IFN通路的科学问题提供解答的契机。

Vago蛋白家族是具有单vwc (von Willebrand factor type C)结构域的分泌蛋白，我们在前期研究中发现凡纳滨对虾的Vago4蛋白在免疫反应中发挥重要作用，其表达受干扰素调节因子（IRF）及Dorsal(NF-κB家族蛋白)通路的调控。本项目针对凡纳滨对虾Vago4介导的免疫调控机制及其免疫功能进行研究，取得了以下成果：发现Vago4能够通过与JAK-STAT信号通路的细胞膜受体Domeless结合促进其内化降解，阻断STAT的磷酸化及入核转运，从而抑制JAK-STAT通路的激活，结合前期研究，这些结果证明Vago4介导了IRF/Dorsal-Vago-JAK-STAT信号轴的调控；进一步对Vago信号轴上下游的调控机制进行研究，揭示了一种由microRNA-1959介导的Dorsal信号通路正反馈调控机制，以及由microRNA-1介导的Vago信号轴的下游JAK-STAT通路与上游Dorsal通路之间的反馈调节环路；鉴定了Vago信号轴调控的一系列下游免疫效应基因，研究了它们在对虾抗病毒及抗菌免疫反应中的功能，并揭示了一系列由效应基因介导的该信号轴的反馈调节机制。本项目的研究证明Vago信号轴在对虾免疫系统的调控中发挥重要作用，能够为对虾感染病害的防治提供了理论基础。目前本项目共发表论文17篇，在投1篇，提交专利申请1项。项目在研期间，项目参与人参加了国内召开的国际学术会议3人次、国内学术会议2场4人次；项目共培养出站博士后1人、毕业博士研究生1人、毕业硕士研究生5人。