Mechanism Of Ubiquitination Regulated By FoxO1 On The Production Of Type Ⅰ Interferon Mediated By RIG-I

Antiviral innate immunity is the first line of defense against virus invasion and plays an important role in the organism.RLR antiviral immune pathway is one of the innate immune pathways.After RNA virus infection,RIG-I is activated and promotes the production of type Ⅰ interferons(IFNs).As a transcription factor,FoxO1 plays essential role in many aspects,such as glucose metabolism.In insulin resistant cells,FoxO1 up-regulates the expression of proinflammatory cytokines,thereby enhancing the inflammatory level of insulin resistant cells or organs.FoxO1 also plays an important role in the study of antiviral innate immune mechanism.It has been reported that FoxO1 participates in the regulation of RLR and TLR4 signaling pathways,however,its specific regulatory mechanism is still unclear.In order to study the mechanism of FoxO1 in the antiviral immune pathway,we constructed FoxO1 and FoxO1 truncated eukaryotic expression plasmids to explore the mechanism of FoxO1 in RLR antiviral immune pathway.In order to explore the mechanism of FoxO1 in RLR signaling pathway,the recombinant plasmid pCMV5-Myc-FoxO1 and FoxO1 truncated body were constructed.By detecting the m RNA levels of various cytokines in 293 T cells and THP-1 cells under the overexpression of FoxO1 and FoxO1-RNAi by fluorescence quantitative PCR,we found that FoxO1 had negative regulatory effect on type I IFN and downstream gene ISGs.This discovery made us have strong curiosity about how FoxO1 regulates this pathway.Furthermore,subsequent studies found that FoxO1 can regulate the occurrence of this phenomenon by affecting the stability of IRF3 and interacting with IRF3.In exploring the mechanism of affecting the stability of IRF3,we found that FoxO1 regulates ubiquitin proteasome pathway to promote the degradation of IRF3.FoxO1 could promote K48 ubiquitination of IRF3 mediated by E3 ligase TRIM22/TRIM21,and then degrade IRF3.In addition to the above results,we also found that FoxO1 inhibited the K63 ubiquitination of TRAF3 and the interaction between TRAF3 and TBK1.All these results confirm that FoxO1 could negatively regulate the production of type I IFN.In addition,we found that the deletion of DNA binding domain(DBD)inhibited the degradation of IRF3 and promoted the ubiquitination of TRAF3,that is,FoxO1 downregulating the production of type I IFN related to its DBD.Therefore,this study further expands the new important role of FoxO1 in the regulation of RLR mediated antiviral innate immune mechanism.