TRANSIENT UBIQUITIN CROSS-REACTIVE PROTEIN GENE-EXPRESSION IN THE BOVINE ENDOMETRIUM

Bovine ubiquitin cross-reactive protein (boUCRP) is secreted by the en dometrium from days 15 to 26 of pregnancy in response to conceptus-der ived interferon-tau (IFN-tau). We hypothesized that the gene encoding boUCRP was under transcriptional control by the conceptus and IFN-tau. Northern blots using radiolabeled UCRP cDNA revealed a single UCRP tr anscript of (similar to)700 b that was present (P < 0.05) in endometri al cells cultured with 25 nM rboIFN-tau. The UCRP mRNA was not detecte d in endometrium on days 15, 17, 18 or 19 of the estrous cycle (n = 4 cows on each day) or in spleen, kidney, liver, corpus luteum or muscle . Bovine UCRP mRNA was detectable (P < 0.05) in endometrium from pregn ant cows by day 15, reached highest levels by day 17, remained elevate d on days 18, 19 and 21, and then declined to amounts on day 26 that w ere not detectable. Northern blot using radiolabeled ubiquitin cDNA re vealed presence of the two major ubiquitin transcripts UbB (1.2 Kb) an d UbC (2.6 Kb) in all tissues examined. The bovine UCRP cDNA did not c ross-hybridize with these ubiquitin transcripts. We conclude that tran scription of the UCRP gene is transient during early pregnancy and reg ulated by IFN-tau.