Snora31,a Small Nucleolar RNA Interacting CGAS,Positively Regulates The Innate Antiviral Response In Microglia Cells

Objective: Neurotropic alpha-herpesvirus HSV-1 infection is the main cause of herpes simplex encephalitis(HSE),and microglia are the main source of type I interferon after HSV-1infection in the CNS,which mainly relies on the DNA sensor cyclic GMP-AMP synthase(cGAS)-mediated DNA recognition and activation of I-IFN immune responses.However,whether RNA molecules bind to cGAS and regulate its mediated antiviral innate immune response remains unknown.In recent years,it has been found that small nucleolar RNA(sno RNA)plays a key role in the occurrence and development of many diseases,but its relationship with antiviral innate immunity is still unknown.In order to explore the role of the RNA-binding activity of cGAS in its mediated antiviral innate immunity,this topic will identify cGAS-binding sno RNAs and explore their role in cGAS-mediated antiviral innate immune responses in microglia and further elucidated its function and molecular mechanism.Methods: In this study,microglia infected with herpes simplex virus type I(HSV-1)were used as a model,and RNA immunoprecipitation sequencing(RIP-seq)was used to obtain the sno RNA that can bind to cGAS induced by HSV-1 infection of microglia,and selected the sno RNA with the highest fold change in expression level after virus infection for subsequent verification.Microglia with sno RNA knockout mediated by antisense oligodeoxynucleotides(ASO)were tested for functional phenotype by q PCR and Western Blot under cGAS agonist stimulation,HSV-1 and reporter virus strain EGFP-HSV-1 infection.Furthermore,the molecular mechanism was explored by RNA fluorescence in situ hybridization(FISH),nuclear and cytoplasmic RNA separation and q PCR quantification,RNApull-down,RNA immunoprecipitation,laser confocal and immunofluorescence.Results: Microglia induced Snora31 expression,nuclear export and interaction with cGAS under HSV-1 infection.Intervention of its expression suppressed the I-IFN innate immune response of microglia under HSV-1 infection and stimulation with immune agonists,and promoted virus replication in microglia.Mechanistically,Snora31 activates cGAS by interacting with cGAS in microglia to positively regulate its mediated I-IFN production.Mechanistically,Snora31 activates cGAS by interacting with cGAS in microglia to positively regulate its mediated I-IFN production.Conclusions: This study shows that the knockout of Snora31 in microglia increases their susceptibility to HSV-1.Microglia can stimulate the expression of Snora31,go out of the nucleus and bind to cGAS under HSV-1 infection.Snora31 positively regulates the antiviral innate immune response mediated by cGAS by increasing the production of 2’3’-c GAMP after cGAS activation.