Induction of endogenous IFN-alpha and IFN-beta genes by a regulatory transcription factor, IRF-1.

Interferons (IFNs) have an important role in cell growth and differentiation. The most well-known function of IFNs is their antiviral activity; viral infections result in induction of the transcription of the IFN-alpha and IFN-beta genes. Recently we isolated the gene encoding a transcription factor, IRF-1, that may play a part in the induction of IFN genes. Interestingly, the IRF-1 gene itself is virus-inducible, suggesting the importance of de novo production of IRF-1 in IFN gene induction. Here we show that high-level expression of the cloned mouse IRF-1 gene in monkey COS cells results in the induction of endogenous IFN-alpha and IFN-beta genes without viral stimulation. Furthermore, we demonstrate the induction of these genes by an IRF-1/yeast GAL4 chimaeric transcription factor. This may be the first demonstration of the specific induction of silent chromosomal genes by transfection of a single transcription factor gene in mammalian cells.