Molecular Cloning of Ovine and Bovine Type I Interferon Receptor Subunits from Uteri, and Endometrial Expression of Messenger Ribonucleic Acid for Ovine Receptors During the Estrous Cycle and Pregnancy*

Abstract

Interferon-tau (IFN-tau), a type I IFN structurally related to IFN-alpha, is regarded as the major antiluteolytic factor secreted by the conceptus of ruminant ungulate species before definitive trophoblast attachment and implantation. It mediates its effects by acting on the uterine endometrium, where it blunts the normal pulsatile production of PGF2alpha, presumably as a result of its binding to type I IFN receptors. In this study, we describe the complementary DNAs for the two known subunits, IFNAR1 and IFNAR2, of this receptor isolated from bovine and ovine endometrial complementary DNA libraries by homology cloning. Although there is extensive inferred amino acid sequence similarity between bovine and ovine IFNAR1 (92% identity) and between bovine and ovine IFNAR2 (88% identity), they have diverged extensively from the human receptor subunits (approximately 67% and approximately 58% identity, respectively). Despite these differences in primary structure, the respective subunits from all three species are organized similarly in their extracellular and cytoplasmic regions, and the bovine and ovine subunits have each retained a number of polypeptide motifs implicated in signal transduction. These uterine receptors also appear not to be splice variants. The cloned ovine IFNAR1 subunit, for example, possesses the expected four extracellular SD100 domains of full-length bovine and huIFNAR1, and only the homologs of the so-called long form (huIFNAR2c) of human IFNAR2 have so far been identified. RT-PCR procedures indicate that the messenger RNA for both subunits are found, not only in endometrium, but in all other tissues examined except those ofpreimplantation conceptuses, which presumably cannot respond to the IFN-tau they produce. Quantitative RNase protection assays of ovine endometrial RNA show that the expression of neither subunit changes greatly during the estrous cycle or pregnancy. These data suggest that the type I IFN receptor, which is expressed by the endometrium and binds IFN-tau, is probably not a structurally unusual form.

Antiviral activities of the soluble extracellular domains of type I interferon receptors

“…Full-length cDNAs for ovIFNAR1 previously have been characterized (19,20). Another cDNA, cloned from an ovine endometrial cDNA library (19), lacked the region encoding the fourth SD100 subdomain, the entire transmembrane domain, and the cytoplasmic domain of IFNAR1 ( Fig.…”

“…1). IFNAR1 has been cloned from human (17), bovine (18,19), ovine (19,20), murine (21), and chicken cells (22). A soluble form of human (hu) IFNAR2 was first purified as an IFN-␣ binding protein from urine (IFNAR2a; ref.…”

cDNA cloning, genomic structure and mRNA expression pattern of porcine type I interferons receptor 2 gene

“…In this study, we cloned the full length cDNA of the porcine IFNAR2 gene, analysed its genomic structure and investigated its mRNA expression pattern. The genomic structure of porcine IFNAR2 contains nine exons and eight introns, similar to that of cattle (Han et al. , 1997a,b).…”

REVIEW ARTICLE: Control of Interferon‐Tau Expression During Early Pregnancy in Ruminants

“…In non-pregnant cows, oxytocin-dependent pulses of prostaglandin F2a (PGF2a) are released from the endometrium at days 17 to 20 post-estrus and travel to the ovaries through a local countercurrent exchange mechanism to cause functional and structural CL regression. 33,34 One of the primary ways that IFN-s promotes continued CL function is by preventing the oxytocin-induced release of PGF2a. The luminal and superficial glandular epithelia are primary sources of PGF2a during luteolysis, and oxytocin acts on these target tissues by binding to its plasma membrane-associated receptor, which is expressed late in diestrus coincident with the initiation of luteolysis.…”