Ubiquitin is physiologically induced by interferons in luminal epithelium of porcine uterine endometrium in early pregnancy: global RT-PCR cDNA in place of RNA for differential display screening.

Early in the course of pregnancy, at the preimplantation stage, the pig embryo is likely to exert a paracrine effect on the tissue intended to receive it, via the secretion of interferons. Our observations show that trophoblastic interferons induce an increase of some mRNAs in the epithelial cells of the gilt endometrium, which would illustrate this phenomenon. The increase of four mRNAs, whose corresponding cDNAs are dD1, dD2, dD3 and dD4, has been examined in this study. The method used is similar to Northern blot analysis except that mRNAs in the blot are replaced by cDNAs produced from total cellular poly(A)+ mRNAs by global reverse-transcription polymerase chain reaction (RT-PCR). Northern blot hybridization requires a considerable quantity of starting material--which we estimate in this study to be several million porcine endometrium cells--whereas the RT-PCR-based method gives comparable results starting with only a few cells--about 200. Using this method, the differential nature of dD1, dD2, dD3 and dD4 was shown. dD2 and dD3 correspond to genes already identified as interferon-induced: the beta2-microglobulin and Finkel-Biskis-Reilly murine sarcoma virus-associated ubiquitously secreted protein (FAU). dD1 corresponds to a still unidentified gene. dD4 encodes for the porcine UbA52 ubiquitin. Up to now, the increase in ubiquitin mRNA as a result of interferon effect has not been reported and is discussed in view of recent publications.