Ubiquitin cross-reactive protein gene expression is increased in decidualized endometrial stromal cells at the initiation of pregnancy

Ubiquitin cross-reactive protein (UCRP; also known as ISG15) is an interferon-upregulated protein implicated in the response to viral infection. An equivalent protein has been demonstrated within the bovine uterus in early pregnancy in response to conceptus-derived interferon-tau. We have previously shown the upregulation of UCRP within decidualized stromal cells of the human and non-human primate endometria. We now show that an increase in UCRP gene expression within the decidualized stromal cell accompanies these increased protein concentrations. Using Northern blotting techniques we demonstrate basal concentrations of URCP mRNA within the non-pregnant endometrium and an increase in signal within some decidual specimens of first trimester decidua. This signal may represent increased URCP transcription within the sub-population of stromal cells that undergo decidualization, since this cell type exhibits an increase in UCRP message as detected by in-situ hybridization.