The Role of Long Noncoding RNA BST2-2 in the Innate Immune Response to Viral Infection.

Long noncoding RNAs (lncRNAs) widely exist in the cells and play important roles in various biological processes. The role of lncRNAs in immunity remains largely unknown. lncRNA BST2-2 (lncBST2-2) was upregulated upon viral infection and dependent on the interferon (IFN)/JAK/STAT signaling pathway. There was no coding potential found in the lncBST2-2 transcript. Overexpression of lncBST2-2 inhibited the replication of hepatitis C virus (HCV), Newcastle disease virus (NDV), vesicular stomatitis virus (VSV), and herpes simplex virus (HSV), while knockdown of lncBST2-2 facilitated viral replication. Further studies showed that lncBST2-2 promoted the phosphorylation, dimerization, and nuclear transport of IRF3, promoting the production of IFNs. Importantly, lncBST2-2 interacted with the DNA-binding domain of IRF3, which augmented TBK1 and IRF3 interaction, thereby inducing robust production of IFNs. Moreover, lncBST2-2 impaired the interaction between IRF3 and PP2A-RACK1 complex, an essential step for the dephosphorylation of IRF3. These data shown that lncBST2-2 promotes the innate immune response to viral infection through targeting IRF3. Our study reveals the lncRNA involved in the activation of IRF3 and provides a new insight into the role of lncRNA in antiviral innate immunity. IMPORTANCE Innate immunity is an important part of the human immune system to resist the invasion of foreign pathogens. IRF3 plays a critical role in the innate immune response to viral infection. In this study, we demonstrated that lncBST2-2 plays an important role in innate immunity. Virus-induced lncBST2-2 positively regulates innate immunity by interacting with IRF3 and blocking the dephosphorylation effect of RACK1-PP2A complex on IRF3, thus inhibiting viral infection. Our study provides a new insight into the role of lncBST2-2 in the regulation of IRF3 signaling activation.