Two contact regions between Stat1 and CBP/p300 in interferon gamma signaling

Interferon gamma (IFN-gamma) induces rapid tyrosine phosphorylation of the latent cytoplasmic transcription factor, Stat1, which then forms homodimers translocates to the nucleus and participates in IFN-gamma-iuduced transcription. However, little is known of the interactions between Stat1 and the general transcription machinery during transcriptional activation, We show here that Stat1 can directly interact with the CREB-binding protein (CRP)/p300 family of transcriptional coactivators. Specifically, two interaction regions were identified: the amino-terminal region of Stat1 interacts with the CREB-binding domain of CBP/p300 and the carboxyl-terminal region of Stat1 interacts with the domain of CBP/p300 that binds adenovirus EIA protein, transfections experiments suggest a role for these interactions in IFN-gamma-induced transcription, Because CBP/p300-binding is required far the adenovirus E1A protein to regulate transcription of many genes during viral replication and cellular transformation, it Is possible that the anti-viral effect of IFN-gamma is based at least in part on direct competition by nuclear Stat1 with E1A for CBP/p300 binding.