TRIM 22 plays an important role in IFNs-mediated antiviral activity. We previously demonstrated that IRF-1 was crucial for constitutive and IFNs-induced TRIM22 expression. Here, we further investigated the molecular mechanisms of IRF-1 in promoting TRIM22 expression. Using in vitro DNA affinity binding assay and in vivo chromatin immunoprecipitation assay, we found that IFN-γ stimulation significantly enhanced the binding of p300 and PCAF, but not other co-activators such as GCN-5, SRC-1 and ACTR, to the 5’ extended IFN-stimulating response element-containing region of TRIM22 promoter together with IRF-1. Overexpression and knockdown analysis demonstrated that it was p300, but not PCAF, that functioned as a transcriptional co-activator of IRF-1 in IFN-γ-mediated TRIM22 production. Further study revealed that p300 mainly participated in the IRF-1-mediated TRIM22 expression by recruiting RNA polymerase II to TRIM22 promoter, and this effect was independent on its histone acetyltransferases activity. Our study indicated that p300 might serve as a bridge between IRF-1 and the basal transcriptional apparatus in TRIM22 induction.
- Copyright © 2013 by The American Association of Immunologists, Inc.