Janus kinase/signal transducer and activator of transcription 3 signaling pathway is crucial in chemokine production from hepatocytes infected by dengue virus

Abstract

Hepatocytes are one of the important targets in dengue virus (DV) infection. Chemokines produced in DV infection play important immunopathogenic roles. We previously showed that DV infection can directly activate signal transducer and activator of transcription 3 (STAT3) in dendritic cells. In the present study, we examined the possible involvement of the Janus kinase (JAK)/STAT3 pathway in chemokine production from DV-infected hepatocytes. HepG2 cells were infected by DV. The activation of STAT3, nuclear factor-kappaB (NF-κB) and other transcription factors was determined by Western blotting or electrophoretic mobility shift assay. The concentrations of chemokines were measured by enzyme-linked immunosorbent assay. Virus titers were determined by plaque assays. A genetic manipulation with short hairpin RNA (shRNA) was applied to knock-down STAT3. Chemotaxis assays were used to evaluate cell migration. We observed that DV infection induced phosphorylation of STAT3 and its DNA-binding activity and such effects were attenuated by the inhibitor of JAK2 or JAK3. Blocking JAK2 or JAK3 reduced DV-induced cell migration and production of chemokines like interleukin-8 and regulated upon activation, normal T-cell expressed and secreted (RANTES). At high doses, the JAK2 but not JAK3 inhibitor could significantly inhibit DV production. Knocking down STAT3 with shRNA suppressed DV-induced STAT3, NF-κB and AP-1 activation. Furthermore, reduction of STAT3 suppressed DV-induced chemokine production and cell migration but had no effect on virus production. In conclusion, the results show that the JAK/STAT3 pathway is critical in chemokine production from DV-infected hepatocytes. Targeting this pathway may be of benefit in the therapy of DV-induced immunopathologies.