Differential and cell type specific expression of murine alpha-interferon genes is regulated on the transcriptional level.

In mouse cells induced with virus infection or dsRNA, the relative levels of alpha-4 interferon mRNA were higher than the levels of alpha-1 and alpha-6 mRNAs; the ratio between relative levels of alpha-4 and alpha-1 or alpha-6 mRNA was, however, dependent on the cell type. Recombinant plasmids, in which the expression of chloramphenicol acetyltransferase (CAT) gene was directed by the promoter regions of alpha-1, alpha-4 or alpha-6 interferon genes were constructed and their inducible expression was studied either in transient assay or in permanently transfected mouse cells. The highest levels of CAT activity and CAT mRNA were observed with alpha-4 CAT plasmid, while the expression of alpha-1 CAT was consistently higher than that coded by alpha-6 CAT plasmid; the ratio between CAT activities coded by alpha-4 CAT and alpha-1 CAT was dependent on cell type. However, in heterologous Vero cells, the transfected alpha-1 and alpha-4 genes were expressed constitutively, and the levels of mRNAs were comparable. These results show that the difference in the relative levels of individual alpha-1 and alpha-4 mRNAs reflects the transcriptional inducibility of the respective promoter regions.