Synergism of type I and type II Interferons in stimulating the activity of the same DNA enhancer

Abstract
Type I and type II interferons (IFNs) can act synergistically to activate the transcription of the 2-5A synthetase gene. We used in vivo functional assays of sequences from the gene promoter region to determine which DNA segment mediates the gene induction by IFNγ and the synergistic effect. We found that the type I IFN-inducible enhancer (or IRS) of the 2-5A synthetase gene also confers inducibility by type II IFN to a reporter CAT gene, though the time course and dose response of the induction by the two IFNs are quite different. A clear synergism of the two IFNs in stimulating the IRS is observed at low doses of the two IFNs