GSE68442
A novel role for Argonaute 4 in mammalian antiviral defense
The four mammalian Argonautes, (AGO1-4) are thought to be functionally redundant, with the exception of AGO2 that exclusively possesses catalytic activity used for microRNA processing or RNA interference (RNAi). Here we identify a unique and specialized role for AGO4 in an interferon (IFN)-independent mode of antiviral defense. High throughput sequencing and crosslinking immunoprecipitation (HITS-CLIP) experiments of AGO1-4 during influenza infection of macrophages and fibroblasts, selectively deficient in individual AGOs or Dicer, showed that influenza-derived RNAs preferentially bound to AGO2 and AGO4. We found that only AGO-bound influenza RNAs <21 nt in length were lost in Dicer-deficient cells, with the remaining viral RNAs selectively lost in AGO4 deficient cells. AGO4-deficient cells and mice were hyper-susceptible to infection by multiple viruses, independent of type I IFN signaling or production. Conversely, infected AGO1- or AGO3- deleted cells displayed no difference in viral titers. Together, our data demonstrate the importance of AGO-bound RNAs for defense against pathogenic viruses, and assign a novel and unique role for AGO4 in this process. Overall design: Immunoprecipitation of AGO-bound RNA after UV crosslinking using pan AGO antibody recognizing all 4 AGOs in AGO1, 2, 3, 4 KO macrophages -/+ Influenza A (PR/8/1934)