O-GlcNAc transferase senses influenza viral RNA and restricts viral infection by integrating innate immunity and lipid metabolism
Viral infection induces robust reprogramming of metabolic pathways in host cells. However, whether host metabolic enzymes detect viral components remains unknown. Our group and others previously identified O-GlcNAc transferase (OGT), an important glucose metabolic enzyme, as a crucial mediator of the antiviral immune responses. Here, we discover an enzyme-independent function of OGT in restraining influenza A virus (IAV) infection in addition to its enzyme-dependent effect on MAVS-mediated antiviral immunity by studying a mouse model with an enzyme-inactive OGT. Biochemical studies reveal a critical antiviral effect based on OGT N-terminal tetracopeptide repeat-4-domain binding to IAV genomic RNA. This binding causes the translocation of nuclear OGT to cytosolic lipid droplets (LDs) to destabilize LDs-coating perilipin 2, thereby limiting LDs accumulation and in turn virus replication. In sum, our findings reveal OGT as a multifaceted metabolic sensor that integrates MAVS signaling and lipid metabolism to combat viral infection. Overall design: In this project we study the binding of OGT protein and influenza A virus (IAV) genomic RNA, the experiment design is below: We transfected 293T cells with pFlag-OGT plasmid (Flag empty plasmid as control) and infected the cells with influenza virus (no infection as control, we labeled them with “Mock” groups), then harvested the cells for the immunoprecipitation (IP) assay (including input samples and IP samples), total are 8 samples as below: 1,FM_IP:Flag empty vector Mock IP sample; 2, GM_IP: Flag-OGT Mock IP sample; 3,F8_IP: Flag empty vector IAV (PR8 strain) IP sample; 4, G8_IP: Flag-OGT IAV (PR8 strain) IP sample; 5,FM_N: Flag empty vector Mock Input sample; 6, GM_N: Flag-OGT Mock Input sample; 7, F8_N: Flag empty vector IAV (PR8 strain) Input sample; 8,G8_N: Flag-OGT IAV (PR8 strain) Input sample. After IP assay, we extracted the total RNA using TRIzol from all samples for RNA-Seq.