The chicken Mx promoter contains an ISRE motif and confers interferon inducibility to a reporter gene in chick and monkey cells.

Genomic DNA containing the first four exons and upstream sequences of the interferon (IFN)-inducible chicken Mx gene was cloned and sequenced. The exon/intron structure of the chicken Mx gene resembles that of the mouse Mx1 gene: exon 1 is very small, the first intron contains a noncoding exon 1' that is alternatively spliced in different chicken breeds and exon 2 harbors the ATG initiation codon. Exons 3 and 4 of the chicken and mouse Mx genes have identical lengths and the encoded polypeptides show a high degree of homology. Sequences upstream of the transcription start site functioned as an IFN-inducible promoter in chick and monkey cells when cloned in front of a promoterless luciferase reporter gene. Deletion analysis suggested that the sequence 5'AGTTTCGTTTCT3' is of critical importance for inducibility. It conforms to the consensus sequence of the IFN-stimulated response element (ISRE) present in Mx and other IFN-alpha/beta-inducible promoters of mammals. These results suggest that the ISRE motif has been conserved and that it regulates expression of IFN-inducible genes in both mammals and birds.