The Effect And Mechanism Of JAK/STAT Signaling Pathway On Enterovirus 71-Infected THP-1 Cells

objective:To investigate the relationshipbetween the Janus kinase/signal transducers and activators of transcription(JAK/STAT) signaling pathway and EV71 infection,which provides new mechanism for research and development of antiviral drugs.Methods:EV71 were propagated in human rhabdosarcoma(RD)cells and the viral titers were determined by Reed-Muench method. The mRNA levels of 4 interferon stimulated genes(ISGs) including MXA, ISG15, OAS1 and ISG56 were detected by real-time quantitative reverse transcription-PCR(qRT-PCR) in EV71-infected THP-1 cells. Treated with IFN-β1a(1000 u/ml)and IFN-α2b(1000 u/ml), EV71 infection and replication were observed. The total or phosphorylation levels of IFNAR1, JAK1, TYK2, STAT1, and STAT2 were analyzed by Western blot. In addition, pretreated with the inhibitor fludarabine(20μM) or knockdown by short hairpin RNA(shRNA) on STAT1, the expression levels of 4 ISGs and EV71/VP1 were evaluated.Results:EV71 infection stimulated the transcription of IFN-β and MXA, OAS1 and ISG56 inTHP-1 cellsand enhanced the phosphorylated levels of JAK1, TYK2 and STAT1. Similarly, treated with IFN-α2b and IFN-β1a, the phosphorylated levels of JAK1, TYK2 and STAT1 inEV71-infected THP-1 cells were upregulated, while the level of IFNAR wasn’t changed.When THP-1 cells were treated with fludarabine(20 μM),the total and phosphorylation of STAT1 decreased.Moreover, the mRNA levels of ISG56, OAS1 and MXAdownregulated, and the protein level of EV71/VP1 also decreased. Similarly, the knockdown of STAT1 gene by shRNA could effectively inhibit STAT1 and down-regulate the transcription of MXA, OAS1 and ISG56, resulting in impairedviral replication.Conclusion:Our results indicated that EV71 infection stimulated the activation of JAK/STAT signaling pathway, which triggers innate immune response in human body.These results suggest that THP-1 cells plays a role in immune response during EV 71 infection.