Figure 4. PCBP2 enhances the effect of IFN-α through binding STAT1 and STAT2 mRNA and up-regulates the expression of the two signal molecules in IFN-α pathway.

RIP assay and targeted qRT-PCR confirmed the enrichment of different IFN-α signal pathway factor mRNAs in the PCBP2-RNA complex. (A) Detection of the PCBP2-RNA complex precipitated with streptavidin beads using anti-PCBP2 or anti-GFP antibody and streptavidin by Western blotting. (B) Targeted qRT-PCR was carried out on RNA isolated from RNP complexes precipitated in RIP assay. Analysis of mRNAs isolated from a GFP RIP reaction was carried out in parallel as nonspecific binding. α-globin was used as positive control. The enrichment of each mRNA was compared to the GFP control. Each bar represents the average of triplicate data points with standard deviation represented as the error bar. (C) PCBP2 up-regulated the expression of STAT1 and STAT2 after the treatment of IFN-α while other factors remained intact. The R1b cells were transfected with pcDEF vector or pcDEF-PCBP2. Forty-eight hours after transfection, the cells were treated with 100 IU/mL IFN-α and paired with untrasfected cells. Next, 6 hours later, the cell lysates were assessed by Western blotting.