The Regulatory Role And Mechanism Of Glutathione Transferase GSTP1 In The CGAS-STING Signaling Pathway

BackgroundViral infections pose a serious threat to human health,and sudden large-scale infectious diseases even disrupt the social order.The human organism has developed a sophisticatedly regulated antiviral immune system in the process of co-competition and derivation with viruses.However,viruses can also cause abnormal activation of innate immunity through multiple pathways to achieve immune escape and persistent infection.Therefore,studying the interaction between viruses and the immune system and further elucidating the regulatory mechanisms of antiviral innate immunity are essential scientific problems.In the innate immune system,pattern recognition receptors(PRRs)recognize relatively conserved pathogen-associated molecular patterns(PAMPs)in the viral structure to initiate an innate immune response against the virus.The stimulator of interferon genes(STING)is a key junction molecule in the antiviral innate immune system.STING recognizes the second messenger cyclic GMP-AMP(cGAMP).cGAMP is synthesized by the DNA receptor cyclic guanosine-adenylate synthase(cGAS).STING induces the activation of the downstream transcription factors interferon regulatory factor 3(IRF3)and nuclear factor κB(NF-κB),which ultimately lead to the production of type I interferon(IFN-α/β)and pro-inflammatory cytokines.STING plays an important role in the host’s antiviral immune response.Viral infection induces massive production of reactive oxygen species clusters(ROS),which in turn leads to enhanced oxidative stress(OS),a signature of immune cell activation.Excessive oxidative stress activates intracellular antioxidant systems.Glutathione(GSH)is the predominant intracellular antioxidant and plays an essential role in life activities.One of the vital functions of GSH is to covalently modify oxidatively damaged cysteine residues via glutathione S-transferases(GSTs)to induce S-glutathionylated modifications in target proteins thereby affecting their function.By analyzing reported studies of the high-throughput protein-protein interaction network,we found a possible interaction between STING and glutathione transferase Pi(GSTP1),which was confirmed by co-Immunoprecipitation(co-IP)experiments.GSTP1 is a member of the GSTs transferase family and is involved in catalyzing protein Sglutathionylation modifications.However,whether GSH-mediated S-glutathionylation modification affects the function of STING is unknown to us.This research discusses this issue.ObjectivesThis research aims to explore and investigate the role of GSTP1 in STING activation and to further reveal the regulatory mechanism of STING-mediated antiviral innate immune response.Methods and Results1.GSTP1 binds to STINGBy analyzing reported studies of the high-throughput protein-protein interaction network,revealed a possible interaction between STING and GSTP1,which was confirmed by co-IP experiments.2.GSTP1 inhibits cGAS-STING pathway activationBy Western Blot and RT-PCR,it was found that knockdown of Gstp1 in mouse peritoneal macrophages or knockout of GSTP1 in THP-1 cell lines promoted phosphorylation of downstream molecules of STING and Ifnb transcription;knockout of GSTP1 inhibited HSV-1 replication.Meanwhile,experiments using Ezatiostat,an inhibitor of GSTP1,in mouse peritoneal macrophages as well as THP-1 cell lines showed the same findings and revealed that inhibition of GSTP1 promoted the expression of IFN-stimulated genes(ISGs)downstream of STING.3.The mechanism of the cGAS-STING pathway affected by GSTP1The presence of S-glutathionylation modification of STING was found by co-IP combined with Western Blot,and inhibition of GSTP1 could reduce the Sglutathionylation modification of STING.ConclusionThe abnormal activation of STING,a core factor in the activation of the immune response,is closely associated with viral disease development.This study identified the role of GSTP1 in STING-mediated antiviral innate immune response,which provides a basis for subsequent uncovering of the relationship between S-glutathionylation modification and innate immune response,and provides new ideas for the treatment of STING abnormal activation-related diseases.