Bovine Interferon-τ Stimulates the Janus Kinase-Signal Transducer and Activator of Transcription Pathway in Bovine Endometrial Epithelial Cells1

Trophoblastic bovine interferon-tau (bIFN-τ) suppresses luteolytic pulses of endometrial prostaglandin F2α(PGF2α) at the time of maternal recognition of pregnancy. This results in maintenance of the corpus luteum in cattle. The hypothesis that effects of bIFN-τ in the endometrium were through activation of the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway of signal transduction was tested. Whole cell, cytosolic, and nuclear extracts from bovine endometrial cells treated with bIFN-τ were analyzed by immunoprecipitation, immunoblotting, and electrophoretic mobility shift assays in a series of dose- and time-dependency experiments. Bovine IFN-τ stimulated tyrosine phosphorylation, homo- and heterodimer formation, nuclear translocation, and DNA binding of STAT proteins 1, 2, and 3. Moreover, bIFN-τ induced synthesis of interferon-regulatory factor. In conclusion, bIFN-τ stimulates the JAK-STAT pathway in the bovine endometrium. It is proposed that activation of the JAK-STAT pathway is involved in regulating the antiluteolytic effects of bIFN-τ.