Study Of Miz1 Negative Regulation On Type ? Interferon Production In Innate Anti-influenza Immunity

Influenza virus is the most common respiratory pathogen,continuous flu pandemic cause serious threat to human health.Due to the inherent mutation of influenza virus,the prevent efficacy of influenza vaccine is limited;with the widespread use of anti-influenza drugs,the appearance of drug-resistant strains is limiting the efficiency of anti-influenza drugs.Therefore,it is an urgent need of researchers to find novel anti-influenza treatments.The role of innate immune response in infectious diseases progression has attracted widespread attention.With the deepening of research in recent years,a series of host factors involved in regulatiing innate immune responses have been gradually discovered,which are regarded as important antiviral target resources according to their lower susceptible mutation rate and potent broad antiviral spectrum.The zinc finger transcription factor Miz1(Myc-interacting zinc finger protein 1;Zbtb17)was originally identified as a binding partner of the proto-oncogene Myc by a yeast two-hybrid approachhe,playing critical roles in cell proliferation,differentiation,cell cycle progression and apoptosis through transcriptional activation or repression of its target genes associated with its POZ(Pox virus and Zinc finger)domain.As a significant transcription factor,Miz1 suppressed LPS and bacteria infection induced innate immune response in mice lung through transcriptional repression on C/EBP8 promoter,which suggested that Miz1 can be an innate immune regulator associated with host immune regulation towards different stimulations.Influenza is a common respiratory pathogen,whether Miz1 regulates the innate immune response to other lung injurious stimuli such as virus infection remains elusive.Our study mainly focused on the role of Mizl in regulating influenza virus infection.Our preliminary data show that geneic destruction of Mizl POZ structure in micw lung epithelium significantly enhanced the resistance of mice to influenza virus infection:improved survival rate and reduced weight loss,accompany with lower viral load in the lungs of Miz1?POZ-lung mice compared to the Miz1(POZ)fl/fl control mice.At day 4 after influenza virus infection,the critical antiviral cytokines type ?interferons in Miz1?POZ-lung mice lung BALFs was higher than that in Mizl(POZ)fl/fl mice,the differences of other proinflammatory cytokines were comparable.We hypothesized that Mizl might regulate host antiviral innate immunity through regulating type I interferon induction during virus infection.Consistently,in vitro,we found that knockout Mizl gene in mouse lung epithelial 12(MLE12)cell could enhance the expression of IFN-a and IFN-? after influenza virus infection,and reduce influenza virus replication in the cell.More importantly,the regulation of Mizl on influenza virus infection is closely related to its transcriptional function.In this study,we also found that viral infection could cause the accumulation of Miz1 in host cells,which was mainly related to the degradation of it's E3 ubiquitin ligase Mule during virus infection.The virus helps themselves escape from the host innate immune surveillance by degrading Mule and increasing the expression of Mizl,which in turn reduces the expression of IFN.We also found that influenza viruses promote Mule degradation by hijacking the cullin-rnig E3 ubiquitin ligase family member CUL4B in host cells.Furtherly,using chromatin immunoprecipitation and luciferase reporter gene assays,we revealed that Mizl could bind to IFN-? transcription initiation region through competition with interferon regulatory factors IRF3/IRF7 binding at IFN-?promoter and inhibit IFN-? transcription.At the same time,posttranslational modifications of histones in chromatin of nucleosomes(e.g.,acetylation,methylation,etc.)are also associated with gene expression.During influenza virus infection,we found Mizl could recruit histone deacetylase 1(HDAC1)to IFN-? transcription initiation domain and decrease the acetylation of histone H3 in IFN-? nucleosomes,t thus inhibiting the expression of IFN-? after influenza virus infection.In summary,our study found that Mizl protein plays an important regulatory function in influenza virus infection for the first time,and provided direct genomic evidence that Mizl was involved in the regulation of IFN-? transcription.At the same time,our experiments found the regulation mechanism of Mizl and its related proteins in host after viral infection,provideing new insights into how does the virus help self-replication by countering the host antiviral immune response.This study has deepened our understanding of the host immune response to the virus and the pathogenesis of the influenza virus,providing theory basics for develoing novel anti-influenza therapeutics.