Mechanism Of Anti-influenza Innate Immune Response Mediated By Transcriptional Regulatory Factors PCF11 And SNW1

Seasonal influenza epidemics and pandemics outbreaks are major threat to human health and impose a considerable economic burden for individual and government.Currently,with the challenges of a small arsenal of available drugs and increasing emergence of drug-resistant strains in clinical flu treatment,it's urgent to develop novel antiviral drugs to enrich our "ammunition depot" for influenza treatment.A number of host factors involved in the regulation of influenza A virus(IAV)infection cycle and induced antiviral innate immunity have been identified,which provide potential targets for drugs development with high resistant barrier.As we know,antiviral innate immunity plays a key role in pathogens clearance and priming adaptive immune response,and its dysregulation would affect host with tissure damage or succumbing to virus infection.Here,based on previous genome-wide interference omics studies,we identify two novel transcriptional regulatory factor PCF11 and SNW1 which play a significant role in anviral innate immunity in response to IAV infection.The recent study shows IAV infection induces transcriptional defects at the 3'ends of active host genes,then leads to the expression of aberrant RNAs with 3'extensions which ultimately cause global transcriptional downregulation of physiological transcripts and weaken host antiviral response.Transcriptional regulatory factor PCF11 enrolls in the process of precise cleavage of the pre-mRNA in the 3-untranslated region and subsequent polyA tail polymerization.In our study,we show IAV infection causes the extensive degradation of PCF11 blocked completely by the treatment of autophagic inhibitor bafilomycin A1,which indicates IAV-induced autophagy promotes the degradation of PCF11.Then,RNA-seq analysis and in vitro evidence indicate PCF11 knockdown leads to impair host antiviral capacity and decreases the mRNA level of some interferon-stimulated genes(ISGs).Further,PCF11 knockdown inhibits the activation of JAK-STAT induced by recombinant human IFN-? protein and decreases the mRNA and protein level of STAT1 both in static and induced state which indicates PCF11 maintains the activation of JAK-STAT by stabilizing STAT1.To sum up,autophagy induced by IAV infection causes the degradation of PCF11 which decreases the static and induced expression of STAT1 required for activation of ISGs.Failure to induce ISGs ultimately impair the host antiviral innate response and promotes IAV replication and pervasion.The Ski-interacting protein SNW1 acts as a transcriptional co-regulator associated with mRNA splicing and transcription,cell cycle progression,acute and chronic inflammatory responses,however,its role involved in host antiviral innate immune responses remains to be explored.Here,we demonstrated that SNW1 positively regulates IAV-induced expression of pro-inflammatory cytokines and IFN responses,and further inhibits virus replication by performing SNW1 depletion or overexpression approaches.Furthermore,we showed that reduced IFN-? expression caused by interfering SNW1 impairs the activation of JAK-STAT pathway in response to IAV or polyI:C.Importantly,by interacting with the IKK-related kinase IKKy,SNW1 promotes IAV-induced activation of NF-?B and phosphorylation of TBK1 kinase,leading to the induction of antiviral effectors IL-6,CXCL10,IFN-? and MX1.Taken together,our study revealed that SNW1 is an important mediator of host defenses against IAV through the induction of pro-inflammatory factors and IFN signaling,providing novel insights in modulating innate immune responses to protect host from IAV infection.In conclusion,our work identify PCF11 and SNW1 as host protective factors against IAV infection and decipher their detailed mechanisms of action,providing important insights in developing host factor based antiviral drugs with high resistant barrier.