PARENT SESSION
Uterus/Oviduct

THE EXPRESSION OF INTERFERON RECEPTOR POLYPEPTIDES IFNAR1 AND IFNAR2 IN THE OVINE UTERUS.

Rosenfeld, Cheryl¹, Han, Chun-Sheng², Roberts, R. Michael^1,2, ^{1 2}

ABSTRACT- Interferon- (IFN-) is the anti-luteolytic factor released by conceptuses of ruminant ungulate species prior to implantation. Although it is believed to target the uterine epithelium, there are reports of IFN-inducible proteins in the uterine stroma. All Type 1 IFN, including IFN-, seem to exert their action through binding to a common receptor, which consists of two distinct polypeptide subunits, IFNAR1 and 2. While the latter is regarded as the primary binding subunit, both seem to be functionally required. The goal of this work has been to define the localization patterns of the two subunits within the uterus of non-pregnant and early pregnant ewes. We have previously cloned the cDNA for full length ovine IFNAR1 and 2. Here we expressed the entire cytoplasmic domains of both ovine polypeptides as GST-fusion proteins in E. coli. The soluble products were affinity purified on GST-Sepharose and antisera raised in rabbits. We then used immunohistochemistry to examine the localization of both subunits in non-gravid and gravid Days 14 and 15 ovine uteri. Expression of both IFNAR1 and 2 was concentrated in epithelial cells lining the lumen and superficial endometrial glands. Deep regions of the glands were negative for each. The tissue within caruncles expressed IFNAR1 and 2, although expression in remaining stroma was low. Smooth muscle fibers of the myometrium and tunica media of arterioles were positive for both subunits. Interestingly, IFNAR2 staining was higher than that for IFNAR1 in uterine epithelium, while the reverse was true for the smooth muscle fibers, where IFNAR1 was predominant. No difference in cellular staining between pregnant and non-pregnant uteri was observed. These studies demonstrate the anticipated co-localization of IFNAR1 and 2 in cells of the superficial uterine epithelium, which are presumed to elaborate the luteolysin, PGF2, and are thus considered the prime targets for IFN- action. However, they also indicate an unexpected degree of differential staining within other uterine cell-types. The relatively high staining in caruncular stroma suggests that these cells might also respond to IFN-. Furthermore, these data indicate that the expression of neither subunit is induced by the presence of a conceptus. Supported by NIH grant HD 21896.

KEY WORDS: uterus, IFN-, pregnancy, maternal recognition of pregnancy