The Molecular Mechanisms Of Autophagy Induced By VP2 Protein Of Foot-and-mouth Disease Virus

Foot-and-mouth disease(FMD)is a brachychronic,highly contagious disease,wich mainly infects domestic and wild cloven-hooved animal species.Foot-and-mouth disease virus(FMDV),a single stranded RNA,is the pathogeny of FMD,which is the member of the genus Aphthovirus of the family Picornaviridae.The highly infectivity of FMDV makes it a main animal health concern in worldwide.Autophagy is a highly conservative cytosolic catabolic process depending on lysosomes that degrades unnecessary macromolecular substance and damaged organelles,and has basic roles in survival,development and homeostasis in cells.Autophagy is also integral to human health and is involved in a serious of diseases.Many signaling molecules can regulate autophagy.Our laboratorary has reported that both FMDV and inactivated FMDV could induce autophagy,which proteins of FMDV played an important role in inducing autophagy and how it induced autophagy were unclear.Our research is aimed to explore whether the nucleocapsid protein of FMDV play an important role in PK-15 cells in inducing autophagy and how it induces autophagy.Firstly we respectively express the nucleocapsid proteins in PK-15 cells and then using laser scanning confocal microscope and western blotting to examine LC3 B,the marker of autophagy.The expression of LC3B-II was obviously higer in PK-15 cells transfected with VP2 than other nucleocapsid protein of FMDV,indicating that FMDV VP2 could induce autophagy distinctly.We also discovered that VP2 could activate EIF2S1-ATF4 signal pathway and inhibit AKT-MTOR signal pathway.What is more,AKT-MTOR signal pathway inhibiting depended on EIF2S1-ATF4 signal pathway activating.And then FMDV VP2 interact with HSPB1 proteins in PK-15 cells was discovered by immunoprecipitation and liquid chromatography-tandem mass spectrometry(LC-MS/MS).Then we respectively overexpressed or knocked down HSPB1 in PK-15 cells transfecting with VP2 and then tested whether the levels of EIF2S1-ATF4 signal pathway and AKT-MTOR signal pathway were changed.The results suggest that overexpression HSPB1 protein and VP2 in PK-15 cells,the level of autophagy was decreased influenced by activating AKT-MTOR signal pathway and inhibiting EIF2S1-ATF4 signal pathway.On the contray,the level of autophagy was increased.Overall,our results demonstrated that HSPB1 protein in PK-15 cells interacting with FMDV nucleocapsid potein VP2 played an important role in inducing autophagy by activating EIF2S1-ATF4 signal pathway,inhibiting AKT-MTOR signal pathway,which revealed a potential thought of the pathogenic mechanisms of FMDV and the mechnisms of prevention and control.