Long noncoding RNA AVAN promotes antiviral innate immunity by interacting with TRIM25 and enhancing the transcription of FOXO3a

Chengcai Lai; Lihui Liu; Qinghua Liu; Sijie Cheng; Keyu Wang; Lingna Zhao; Min Xia; Cheng Wang; Hongjing Gu; Yueqiang Duan; Zhongpeng Zhao; Lili Zhang; Ziyang Liu; Jianjun Luo; Jianxun Song; Penghui Yang; Runsheng Chen; Xiliang Wang

ng northern blot analysis ( Fig 2G) . The exact 138 transcript length (517 nt) of AVAN was confirmed by 5' and 3' RACE (Table S2) , which 139 revealed that AVAN is polyadenylated (Fig S2G) . Taken together, lncRNA expression profiling Table S3 -S8), suggesting that AVAN participates in innate antiviral immunity. To 149 identify the functions of AVAN, we generated AVAN-overexpressing A549 cells ( Fig 3A) and 150 found that viral replication was strongly inhibited (Fig 3B) . In contrast, virus titer was up-regulated following AVAN knockdown with two specific siRNAs (Fig 3H, I (Fig 3C) . To confirm this result, we performed ELISA to measure IFN-α and IFN-β protein 160 expression and found that IFN-α and IFN-β were strongly up-regulated in 161 AVAN-overexpressing A549 cells during IAV-BJ501 infection ( Fig 3D) . Conversely, these 162 phenomena were abolished by knocking down AVAN (Fig 3J, K) . 163 The above GSEA data and GO analysis showed that the genes related to AVAN were also 164 significantly enriched in chemotaxis and immune cell activation (Fig S4A, Table S9 , S10), the 165 main components of innate immune responses. To explore the role of AVAN in chemotaxis, we 166 collected culture supernatants of AVAN-overexpressing A549cells and performed neutrophil 167 transwell assays, which revealed that AVAN overexpression significantly up-regulated 168 neutrophil chemotaxis during IAV-BJ501 infection (Fig 3E) . These phenomena were disrupted 169 by knocking down AVAN (Fig 3L) . The chemokines interleukin-8 (CXCL8, IL-8) is potent 170 neutrophil chemoattractant (38) and is released by a variety of lung cells, including 171 macrophages and epithelial cells as well as neutrophils themselves (39). IL-8 primarily 172 attracts neutrophils and induces them to release lysosomal enzymes, triggering the respiratory 173 All rights reserved. No reuse allowed without permission.