FIGURE 5.

IRF4 control IFNγ by an independent pathway through IRF1. A, HuT-102 cells were transfected with IRF4 siRNA. The up-regulation of Th1-related proteins was confirmed by Western blot. B, formation of the STAT1-STAT2 heterodimer was confirmed by immunoprecipitation. Whole cell lysates (WCE) were immunoprecipitated with anti-STAT1 antibody, and then the immunoprecipitates (IP) were immunoblotted with anti-STAT1 and STAT2 antibodies. C, neither STAT1 nor IRF9 knockdown reversed the up-regulation of IFN-γ in response to IRF4 knockdown in HuT-102 cells. D and E, HuT-102 cells were transfected with IRF4 and IRF1 siRNAs. Protein expression of IRF1 and IRF4 was determined by Western blot (D). IFN-γ, CXCL10, and IL-17A mRNAs were quantified by real-time RT-PCR (E). F, HuT-102 cells were transfected with an empty vector (mock) or pcDNA-IRF1. At 60 h post-transfection, the expressions of IRF1 and IFN-γ mRNAs were examined by real-time RT-PCR.