Cloning of the porcine interferon-γ receptor and its foeto-endometrial expression in early pregnancy

In early gestation, trophoblastic cells of porcine preimplanting conceptuses transiently and massively secrete two distinct interferons (IFNs), one of which is IFN-γ. In order to localize possible cellular target(s) for this IFN-γ, the expression of the porcine IFN-γ receptor and its developmental regulation have been investigated on the maternal endometrium and on the embryonic tissues. A cDNA encoding the porcine IFN-γ binding-chain (pIFNGR1) was isolated. When expressed in COS-7 cells, it displayed a specific binding to radiolabelled pIFN-γ and was shown to be a glycosylated membrane protein with an apparent molecular mass of 92 kDa. Porcine IFNGR1 mRNA was detected by RT-PCR not only in uterine epithelial cells but also in embryonic tissues from at least as early as day 10 of gestation. Moreover, membrane expression of the pIFN-γ receptor quantified by binding and crosslinking of ³²P-pIFN-γ was demonstrated in uterine epithelium and in the trophoblast. In the trophoblast, expression of the receptor was found to be developmentally regulated: although expression was weak on days 12 and 15 of gestation, it reached a level similar to that found on some IFN-γ–sensitive cells on day 16. This study shows that maternal endometrium is not the only possible target for trophoblastic IFN-γ: the induction of pIFN-γ receptor expression in the trophoblast around day 16 of gestation could suggest the appearance of responsiveness to pIFN-γ in this implanted tissue and therefore a possible delayed autocrine effect of trophoblastic pIFN-γ. Mol. Reprod. Dev. 51:225–234, 1998.© 1998 Wiley-Liss, Inc.