Abstract
Induction of gene transcription in response to extracellular stimuli constitutes an essential aspect of host defense mechanisms. Interferons (IFN) are families of cytokines that have been discovered and extensively characterized in the context of host defense against viral infections. In elucidating the mechanism of transcriptional induction of the IFN genes by viruses, we have discovered two structurally related transcription factors, Interferon regulatory factor 1 (IRF-1) and IRF-2. These two factors, however, function not only as regulators of the IFN system, but are also key transcription factors in the regulation of cell growth and apoptosis. Thus, these studies uncover a complex gene transcription network in which the fate of cellular responses is determined by how the IRF transcription factors function in conjunction with other factors on the promoters of distinct genes under different conditions of the cells.