Sheep antiluteolytic interferon: cDNA sequence and analysis of mRNA levels

Abstract

A cloned cDNA has been isolated by probing a sheep blastocyst cDNA library using a synthetic oligonucleotide representing the N-terminal amino acid sequence of the antiluteolytic protein, ovine trophoblast protein-1. Sequence analysis of the cDNA confirms the 70% homology between the antiluteolysin and the interferon-alpha family of proteins; however, the sequence reported here differs at several points from previously reported amino acid and cDNA sequences for the antiluteolysin. In-vitro translation of day-16 poly(A)+ RNA indicated that antiluteolysin mRNA is a major constituent of total mRNA at this stage of blastocyst development, and Northern blotting confirmed that antiluteolysin mRNA production occurred between days 13 and 22 after oestrus. This is consistent with the stage at which embryonic extracts are antiluteolytic on administration in vivo. These and other data confirm that the ovine trophoblast antiluteolysin is an interferon, and suggest that at least five isoforms of this protein may exist.

Trophoblast interferon and pregnancy

“…The transient nature of IFN-τ secretion Stewart et al (1989) showed by northern blotting of blastocyst mRNA, and Farin et al (1990) demonstrated by in situ hybridization, that oIFN-τ is expressed transiently during a limited period of development, and that its expression is localized to the extra-embryonic trophectoderm of bovid conceptuses (Fig. 1).…”

“…Note the M r of the major product, IFN-τ at 22 kDa, reflects the lack of post-translational processing to remove the signal peptide (C terminal amino acids 1-23) which leads to an M r of 18 kDa in the secreted protein. (Figure from Stewart et al, 1989. ) concentration, which controls uterine glandular secretion, is correlated with IFN-τ production by the conceptus in cattle (Kerbler et al, 1997;Mann et al, 1999).…”

Lack of evidence for the prodection of interreron -α-like species by the cultured human pre-embryo

“…In ruminants, the corpus luteum is maintained as a result of the secretion of a protein (trophoblast protein-1) by the embryo into the lumen of the uterus. Ovine and bovine trophoblast protein-1 (oTP-1, bTP-1) were shown to be related to interferon-a (IFN-a) (Stewart et al, 1987(Stewart et al, , 1989Imakawa et al, 1987) and subsequently named trophoblast interferons (troIFN). Approximately 70% of bTP-1 is identical to the sequence of bovine IFN-a.…”

Peripheral concentrations of a 60-kDa pregnancy serum protein during gestation and after calving and in relationship to embryonic mortality in cattle

“…As in sheep (Martal et al, 1979;Godkin et al, 1982;Imakawa et al, 1987; this signal is an interferon: bTP-1 (bovine trophoblast protein-1) (Helmer etal, 1987;Imakawa et al, 1989;Stewart et al, 1989). bTP-1 interferon is secreted by the conceptus between d 16 and 26 of pregnancy (Bartol et al, 1985) (Beckers et al, 1982).…”