A novel and atypical type one interferon gene expressed by trophoblast during early pregnancy.
Low stringency screening of day 14-15 pig conceptus cDNA library using an interferon (IFN)-omega probe has led to the isolation of a novel type one (type I) IFN gene physiologically expressed by trophoblast during the period of implantation in the uterus. It encodes a 170-amino acid preprotein with two potential N-glycosylation sites and a predicted N-terminal signal peptide of 21 residues. This protein was shorter and richer in Cys residues than other type I IFNs and distantly related to all of them including IFN-tau, the trophoblast IFNs of ruminants, with amino acid identities ranging between 27 and 42%. Moreover, its antiviral activity was resistant to neutralization by antisera directed against several IFN-alpha, -beta, -omega, and -tau family members. The pig genome contained only two intronless, non-allelic loci homologous to the cDNA, one of them corresponding to the cDNA. This gene had a single transcription initiation site. Its upstream putative regulatory regions had no similarity with those of other type I IFN genes and did not display the typical clustering of short sequence motifs thought to be involved in virus inducibility but, instead, a modular structure of 30-40-base pair direct repeats. These data highlight the very atypical characteristics of this gene and its product and suggest that it represents the first member of a yet unknown family of type I IFNs present in other mammalian species according to sequence divergence analysis.
Lefèvre
F
F
Unité de Virologie et Immunologie Moléculaires, Centre de Recherches de Jouy-en-Josas, Institut National de la Recherche Agronomique, France.
Boulay
V
V
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D010064:Embryo Implantation; D005260:Female; D015870:Gene Expression; D015698:Genomic Library; D006801:Humans; D007106:Immune Sera; D007370:Interferon Type I / Q000096:biosynthesis* / Q000235:genetics* / Q000276:immunology; D007372:Interferons / Q000276:immunology; D008969:Molecular Sequence Data; D010802:Phylogeny; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000276:immunology*; D012313:RNA / Q000235:genetics / Q000302:isolation & purification; D012333:RNA, Messenger / Q000096:biosynthesis / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013552:Swine; D014158:Transcription, Genetic; D014162:Transfection; D014327:Trophoblasts / Q000276:immunology*
D007106:Immune Sera; D007370:Interferon Type I; D012333:RNA, Messenger; D012313:RNA; D004247:DNA; D007372:Interferons