Endometrial ISG17 mRNA and a related mRNA are induced by interferon-tau and localized to glandular epithelial and stromal cells from pregnant cows

The interferon stimulated gene product, ISG17, conjugates to bovine uterine proteins in response to conceptus-derived interferon (IFN)-tau. The object ives of the present experiments were to examine induction of ISG17 (0.65 kb ) and a related 2.5 kb mRNA in response to IFN-tau and pregnancy using Nort hern blotting procedures, and to determine cell types in the endometrium th at expressed ISG17 mRNA using in situ hybridization. RNA was isolated from endometrial explants or from bovine endometrial (BEND) cells cultured in th e absence (control) or presence of 25 nM recombinant (r) bolf N-tau for 0, 3, 6, 12, 24, or 48 h, The major ISG17 0.65 kb mRNA and a minor 2.5 kb mRNA were induced (p < 0.05) after 6 h (explants) or 3 h (BEND cells) treatment with rboIFN-tau. Both mRNAs were present in endometrium from day 18 pregna nt cows, but were absent in endometrium from nonpregnant cows. The ISG17 mR NA was localized to stromal and glandular epithelial cells on d 18 of pregn ancy. The 2.5 kb mRNA may encode a novel ISG17 homolog, or a unique polyISG 17 repeat that is similar in structure to the polyubiquitin genes, Because ISG17 mRNA is induced in stromal and glandular epithelial cells, it could b e assumed that ISG17 has a role in regulating intracellular proteins in bot h cell types.