Pregnancy and interferon-tau upregulate gene expression of members of the 1-8 family in the bovine uterus

The 1-8 family (1-8U, 1-8D, Leu-13/9-27) of interferon (IFN)inducible genes encodes proteins that are components of multimeric complexes involved with transduction of antiproliferative and homotypic adhesion signals. Human 1- 8 family members are highly similar and are regulated by type 1 and type 2 IFNs. Because the bovine uterus is bathed in conceptus-derived IFN tau duri ng early pregnancy, it was hypothesized that members of the 1-8 family were upregulated in the bovine uterus during early pregnancy. Oligonucleotide p rimers were designed based on human and rat 1-8U and Leu-13 cDNAs and used in reverse transcription polymerase chain reactions to amplify bovine cDNAs from endometrial RNA. The bovine 1-8U cDNA was sequenced, found to be 84% identical to the human 1-8U, and used to screen a bovine endometrial cDNA l ibrary to isolate the full-length 1-8U and Leu-13 cDNAs. The inferred amino acid sequences of bovine 1-8U and Leu-13 were 72% and 73% identical to the ir respective human counterparts. Bovine 1-8U and Leu-13 retain an amino ac id motif that is conserved in other 1-8 family members and in some ubiquiti n-conjugating enzymes (E2s). This motif is critical for function of E2s in covalently linking ubiquitin to targeted proteins. Northern blotting reveal ed that bovine endometrial 1-8U and Leu-13 mRNAs were upregulated on Day 15 of pregnancy (P < 0.0001) and continued to accumulate through Day 18 of pr egnancy (P < 0.05) when compared with endometrium from nonpregnant cows. Th e bovine 1-8U and Leu-13 mRNAs were also upregulated (P < 0.05) by IFN tau (25 nM) within 3 h, continued to accumulate through 12 h, and reached a pla teau at 12-24 h in cultured bovine endometrial cells. in situ hybridization revealed that mRNAs encoding 1-8 family members were heavily localized to glandular epithelium but also were present to a lesser extent in the lumina l epithelium and stroma. The temporal upregulation of 1-8U and Leu-13 mRNAs by pregnancy and IFN tau and tissue distribution of these mRNAs paralleled closely that of the ubiquitin homolog, IFN-stimulated gene product 17. The se IFN-induced proteins probably work together to prepare the endometrium f or adhesion of the developing conceptus.