COMPLEX INDUCTION OF BOVINE UTERINE PROTEINS BY INTERFERON-TAU

Interferon-tau (IFN-tau) is released by the conceptus and induces two uterine proteins during early pregnancy: ubiquitin cross-reactive prot ein (UCRP) and granulocyte chemotactic protein-2 (CCP-P). The present experiments were designed to determine whether detection (Western blot ) of cytosolic UCRP and release of GCP-2 could be used to examine IFN- tau signal transduction in cultured endometrial explants and primary e pithelial cells. Recombinant (r) type 1 IFNs (rboIFN-tau and rboIFN-al pha; 5, 25, 100 nM) induced UCRP, but only rboIFN-tau induced GCP-2 in explant culture. Recombinant boIFN-tau and conceptus secretory protei ns containing native IFN-tau induced UCRP and GCP-2 in cultured primar y epithelial cells. All concentrations of rboIFN-alpha (25, 50, 100 nM ) induced UCRP, but only the highest concentration induced GCP-2 in cu ltured primary epithelial cells. Interestingly, phorbol ester (100, 50 0, 1000 ng/ml) induced GCP-2, but it had no effect on UCRP. Because ty pe 1 IFNs induce UCRP, IFN-tau probably interacts with the janus kinas e (Jak)-associated IFN-alpha receptor to phosphorylate signal transduc ers and activators of transcription (STAT) and/or interferon regulator y factor-1 (IRF-1). However, IFN-tau-specific induction of GCP-2 may i nvolve a variant type 1 receptor subunit or activators of transcriptio n that are associated with protein kinase C and the Jak/STAT/IRF-1 pat hway.