pSecTagB-IFN-α activates JAK-STAT signal pathway and promotes the induction of IFN-stimulated genes
JAK-STAT pathway is the most crucial one in IFN-α-activated signaling pathways. STAT1 and STAT2 are important transcriptional factors of JAK-STAT pathway, and the phosphorylated STATs translocate to the nucleus and direct the transcription of hundreds of IFN-stimulated genes [19]. So, we further assessed whether transfection of pSecTagB-IFN-α vector could activate JAK-STAT pathway. By qRT-PCR and western blot analysis, we found that the levels of STAT1 and p-STAT1 were up-regulated in HepG2 cells and HepG2.2.15 cells by pSecTagB-IFN-α vector transfection (Figure 3A,B). Additionally, typical IFN-α-induced antiviral effectors, including ISG15, OAS-1 and IFIT-3, were also increased in HepG2 and HepG2.2.15 cells significantly (Figure 3C). These results suggested that JAK-STAT pathway was activated by transfection with human IFN-α expressing vector.