Interferon-stimulated transcription: isolation of an inducible gene and identification of its regulatory region.

A human gene (termed ISG-54K) that is induced from near undetectable levels to high transcriptional activity by alpha- and beta-interferons has been cloned. The genomic structure and nucleotide sequence of the coding region were determined and the RNA initiation site was identified. The 5' portion of the gene was fused with a heterologous gene lacking an active promoter in recombinant plasmid and adenoviral vectors. These fusion genes were used to assess the activity of the ISG-54K promoter in response to interferon. RNA was formed in HeLa cells from recombinant plasmids only in response to interferon. Furthermore, in human diploid fibroblasts, infection with the recombinant adenovirus vector resulted in a 50-fold increase in specific RNA in response to interferon, followed by a subsequent decrease, imitating the natural regulated transcriptional cycle of the endogenous gene.