G3BP1 Promotes PCV2 Replication And PCV3 Mediates NF-κB Pathway Activation

The diseases caused by porcine circovirus type 2(PCV2)infection are known as porcine circovirus-related diseases,which mainly include weaning piglets’ multi-system failure syndrome,pigskin infection and nephrotic syndrome,and reproductive system diseases.It has caused enormous pressure and economic losses to the global pig industry.It has been reported that GTPase-activating protein SH3 domain-binding protein 1(G3BP1)played an provital role against viruses infection,to date,it remains poorly understood about the relationship between G3BP1 and PCV2(Porcine cicrovirus type 2)infection.It has been reported that PCV3 can cause porcine circovirus diseases,such as porcine dermatitis nephrotic syndrome,porcine reproductive disorders,newborn porcine encephalitis and myocarditis,epimembranitis of the arteries and multi-system inflammation.PCV3 infection may lead to imbalance of inflammatory regulation.Inflammatory response is a very complex regulatory network,involving pattern recognition receptors,adaptors,kinases,transcription factors,pro-inflammatory cytokines and various post-translational modifications of proteins.The inflammatory transcription factor NF-κB plays an important role in the inflammatory regulatory pathway.PCV3 and NF-κB signaling pathway research has failed to carry out.In the present study,the eukarytoic expression plasmid and interference RNA were used to up-regulate and down-regulate expression of G3BP1 in PK15 cells,the effect of G3BP1 on PCV2 infection were studied,and the related mechanism was preliminarily studied.These results indicate that there was a significant difference in virus replication 24 hour post infection(hpi)and a more significant difference in virus replication 48 hpi than 24 hpi,indicating G3BP1 could significantly promote PCV2 replication.The cells were stimulated with ISD for 12 h after overexpression or knockdown of G3BP1,it can be found that G3BP1 promotes ISD-induced IFN-β m RNA trascription.Furthermore,G3BP1 could promote IFN-β m RNA trascription 12 hpi.Thus,our study reveals that G3BP1 is necessary for PCV2 efficient replication,likely by up-regulation of IFN-β expression.This paper constructs the two main proteins PCV3 Cap and Rep plasmid,can be found PCV3 rep did not regulate the transcription of the NF-κB promoter,however PCV3 Cap promoted the NF-κB promoter transcription,indirect immunofluorescence assay shows that the PCV3 could promotes the NF-κB signaling pathways of P65 into the nuclear process,WB assay showed that the Cap was significantly promoted the P65 protein phosphorylation of NF-κB signaling pathways,and the degradation of IκBα predominate and phosphorylation,These phenomena indicated that PCV3 Cap could regulate the activation of NF-κB signaling pathway.Moreover,PCV3 Cap significantly promoted the IL6 and TNFα m RNA expression of pro-inflammatory cytokines,which disappeared when NF-κB signaling pathway inhibitor Helenalin was added.This paper found PCV3 Cap could significantly promote RIG1/MDA5 m RNA expression of the RLR signaling pathways,downstream My D88 of Toll-like receptors m RNA expression level significantly enhanced,but the downstream TRIF m RNA expression of Toll-like receptors didn,t change,at the same time,we also found PCV3 Cap significantly promoted IFN-β promoter transcription which wasinduced by POLY : IC,these results suggest that PCV3 Cap may be migrate the NF-κB signaling pathway activation through the RLR and Toll-like receptors signaling pathways.