The transcription factor ISGF3 transduces interferon (IFN)-alpha signals and activates the transcription of cellular antiviral defence genes. Adenovirus E1A blocks the IFN-alpha response, allowing unhindered viral replication. ISGF3 consists of Stat1, Stat2 and p48. Here we show that p300 and/or CBP (CREB-binding protein), which are transcription adaptors targeted by E1A, interact specifically with Stat2. Binding occurs between the first cysteine-histidine-rich region of p300/CBP and the carboxy-terminal segment of Stat2, a domain essential for ISGF3 function. We find that this domain of Stat2 has transactivation potential, which correlates with its binding to p300/CBP. Moreover, E1A represses Stat2 transactivation and IFN-alpha-activated transcription by inhibiting p300/CBP function. This provides a new mechanism for inhibition of the IFN-alpha-activated antiviral response by E1A, and supports the view that E1A binding to p300/CBP has functional significance for adenovirus replication in its natural host.
344 - 347
Adenoviridae, Adenovirus E1A Proteins, Binding Sites, CREB-Binding Protein, DNA-Binding Proteins, Gene Expression Regulation, HeLa Cells, Humans, Interferon-Stimulated Gene Factor 3, Interferon-Stimulated Gene Factor 3, gamma Subunit, Interferon-alpha, Nuclear Proteins, Protein Binding, STAT2 Transcription Factor, Signal Transduction, Trans-Activators, Transcription Factors, Tumor Cells, Cultured, Virus Replication