BmCPV的环RNA vcircRNA_000048抑制病毒感染的机制

We have confirmed that circRNA vcircRNA_000048 produced by Bombyx mori cypovirus (BmCPV) in the infected cells can be potentially translated to micropeptide vcP21 and inhibits virus infection, but the mechanism is unclear. In this project, we are going to study that the regulation of vcircRNA_000048 on viral replication, antiviral immunity of silkworm, binding of antiviral protein NF90 homolog to viral mRNA, expression of silkworm/virus genes, interaction between vcircRNA_000048 and host/ virus proteins to explore the mechanisms of vcircRNA_000048 RNA molecule on depressing virus infection. Further, we are going to study the regulation of micropeptide vcP21 encoded by vcircRNA_000048 on viral replication, expression of genes related to antiviral immunity, cell apoptosis, autophag，and interaction between vcP21 and proteins/nucleic acid to uncover the mechanisms of vcP21 on inhibition of virus infection. This project can uncover functions and action mechanisms of vcircRNA_000048, explain the biological significances of circRNAs produced by virus, and can also realize the antiviral immunity of silkworm from the new perspectives that viral mRNAs can be spliced to circRNAs, help us understand in depth the crosstalk between subtle regulation of virus gene expression and silkworm, and further provide a novel strategy for prevention and cure of B. mori cytoplasmic polyhedrosis.

我们证实BmCPV产生的环RNA vcircRNA_000048能翻译成微肽vcP21、抑制病毒感染，但机制不明。本项目通过研究vcircRNA_000048调节病毒增殖、抗病毒免疫、抗病毒因子NF90同源体与病毒mRNA结合、家蚕/病毒基因表达以及vcircRNA_000048与蛋白的互作，探讨vcircRNA_000048的RNA分子抑制病毒感染的机制；进一步研究vcircRNA_000048翻译的vcP21调节病毒复制、抗病毒免疫、细胞凋亡、自噬相关基因表达及vcP21与蛋白/核酸的互作，探讨vcP21抑制病毒感染的机制。项目不仅能解明vcircRNA_000048的功能和作用机制，阐释BmCPV产生circRNAs 的生物学意义，也可以从病毒mRNA剪接产生circRNAs新视点认识家蚕的抗病毒免疫，加深病毒基因表达精细调控与宿主互作的理解，为质型多角体病的防治提供新的策略。

vcircRNA_000048为BmCPV S5正义链的165−1018nt区域形成的circRNA，其形成和发挥功能的机制不明。本项目证明了vcircRNA_000048存在的真实性，发现vcircRNA_000048延缓BmCPV增殖复制，明确了vcircRNA_000048的亲本RNA断裂位点上、下游25 nt序列以及位于5‘断裂位点、3’断裂位点的“AGAG”是其形成的关键顺式元件，与vcircRNA_000048形成相关的蛋白位于细胞质中，hnRNP Q和DDX5-2参与vcircRNA_000048的形成；探明了vcircRNA_000048-bmo-miR-2753-METT20调节网络。进一步，我们研究了vcircRNA_000048编码蛋白的潜在性，证实vcircRNA_000048可翻译延缓病毒增殖复制的vsp21和vsp34小肽，并明确了vsp21由vcircRNA_000048通过IRES介导翻译产生，而非由它的线性亲本RNA翻译形成，vcircRNA_000048延缓病毒的增殖复制可能归因于vsp21。在此基础上，我们研究了vsp21的作用机制，证实vsp21可与p-IκB-α竞争性结合UCH，激活NF-κB信号通路，诱导自噬, 负调控病毒的增殖。另外，还发现vsp21可通过ROS激活NF-κB通路延缓病毒的增殖复制。总之，本研究发现了病毒circRNA形成新机制，明确了vcircRNA_000048的功能和作用机制。研究结果从病毒RNA剪接产生circRNAs新视点加深了家蚕的抗病毒免疫、病毒基因表达精细调控与宿主互作的理解。