Polymorphic Forms of Expressed Bovine Interferon- Genes: Relative Transcript Abundance during Early Placental Development, Promoter Sequences of Genes and Biological Activity of Protein Products
Multiple interferon (IFN)-t genes exist in cattle, but it has re- mained unclear how many are expressed, the extent of their variation, and whether different genes exhibit similar patterns of expression and code for proteins with similar biological activities. A total of 118 complementary DNA (cDNA) were bi-directionally sequenced from reverse-transcribed bovine (bo) conceptus RNA over the period from blastocyst formation until day 25 of pregnancy. Fourteen different cDNAs, encoding eight different IFN-t, were confirmed unique. All showed high sequence conservation (.98% nucleotide identity; .96% amino acid identity). The cDNA fell into three, recently evolved, phylogenetic groups (t1, 2, and 3). Mean concentrations of IFN-t messenger RNA were greater at day 17 and day 19 than at day 14 and day 25, with different genes showing comparable expression patterns, although there appeared to be a major bias in expression of two genes (for boIFN-t1c and t3a) in blastocysts. Genes representing members of the three boIFN-t groups were cloned. Their promoter regions were conserved over regions considered important for transcriptional ac- tivation. Recombinant protein generated in Escherichia coli from representative genes in the three groups had similar but not identical antiviral activities. In summary, many IFN-t genes, which are prob- ably under similar transcriptional control, are expressed in bovine trophoblast during the peri-implantation period of development. (En- docrinology 142: 2906 -2915, 2001)