Study Of Porcine P58IPK Regulating Porcine Circovirus Type 2-induced Autophagy Through PERK/eIF2? Pathway

Porcine circovirus type 2(PCV2)infection suppresses swine immune response,and/or accompanying with other pathogens mixed infection,thus harms swine industry seriously.PCV2 infection induces autophagy and endoplasmic reticulum stress,and unfolded protein response(UPR)through activating PERK/e IF2? pathway,in addition,both autophagy and PERK/e IF2? pathway facilitate virus replication.Emerging evidences show that UPR may regulate autophagy,while whether PCV2 induces autophagy through PERK/e IF2? pathway remains unknown.Besides,P58 IPK is capable of negatively regulating PERK/e IF2? pathway by inhibiting PERK activity,and it also is a potential PCV2 capsid protein(Cap)-interacting protein.Based on above,this study regards UPR as the cut-in point to investigate the function and mechanism of porcine chaperone P58 IPK in PCV2-induced autophagy.The main results include: 1.PCV2 infection regulated autophagy via PERK/e IF2? pathwayPK-15 cells were treated with PERK specific inhibitor and si RNA respectively,results showed that interfering PERK pathway significantly downregulated PCV2-induced ATG5-ATG12(0.32 vs 0.25,P<0.0001)and LC3-?(0.23 vs 0.07,P<0.0001)expression at 24 hpi,which indicated PCV2 regulated autophagy via PERK/e IF2? pathway.2.P58 IPK regulated PCV2-induced autophagy through PERK/e IF2? pathwayChaperone P58 IPK inhibits PERK activity,thus real-time PCR was performed to measure the expression level of P58 IPK.Results showed,P58 IPK m RNA expression was significantly upregulated at 24 hpi(1.00 vs 1.62,P<0.0001),but it was lower than control at 12,48,72 hpi,which implied P58 IPK was suppressed before and after 24 hpi of PCV2 infection.Overexpression of P58 IPK significantly downregulated PCV2-induced p-e IF2?(0.051 vs 0.037,P<0.0001),ATG5-ATG12(0.07 vs 0.03,P<0.0001)and LC3-?(0.30 vs 0.14,P<0.0001)at 24 hpi.Taken together,results implied P58 IPK overexpression may downregulated autophagy via inhibiting PERK activity.In conclusion,this study demonstrated that PCV2 infection not only induced ER stress,UPR and autophagy,but also regulated autophagy via PERK/e IF2? pathway,and overexpression of P58 IPK downregulated PCV2-induced autophagy through inhibiting PERK activity.Those results may provide clues for discovery of host(pig)genes that regulate PCV2 infection and replication,also lays a foundation for studying host-virus interaction mechanism.