Two contact regions between Statl and CBP/p300 in IFN-γ signaling

Interferon-"/ (IFN-7) induces rapid tyrosine phosphorylation of the latent cytoplasmic transcription factor. Statl, which then forms homodimers, translocates to the nucleus and participates in IFN-7-induced transcription. However, little is known of the interactions between Statl and the general transcription machinery during transcriptional activation. We show here that Statl can directly interact with the CBP/p300 family of transcriptional coactivators. Specifically, two interaction regions were identified: the amino terminal region of Statl interacts with the CREB-binding domain of CBP/p300 and the carboxyl terminal region of Statl interacts with the domain of CBP/p300 that binds adenovirus E1A protein. Transfection experiments suggest a role for these interactions in IFN-7-induced transcription. Because CBP/p300-binding is required for 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-7 is based at least in part on direct competition by nuclear Statl with E1A for CBP/p300 binding.