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General Comment |
Receptor Transporter Protein 4 (RTP4) in Endometrium, Ovary, and Peripheral Blood Leukocytes of Pregnant and Cyclic Ewes. Gifford CA et al. Interferon-tau (IFNT) is secreted by the conceptus trophoblast and signals pregnancy recognition in ruminants. IFNT regulates expression of genes in the endometrium, peripheral blood leukocytes (PBL), and corpus luteum (CL). Microarray analysis identified that expression of (chemosensory) receptor transporter protein 4 (RTP4) increased in PBL during early pregnancy in cows. Here, we cloned and characterized RTP4 transcription during early pregnancy in ewes. Endometrium, PBL, and CL were collected on Days 11, 13, and 15 of the cycle and Days 11, 13, 15, 17, and 19 of pregnancy. Northern blot analysis revealed an expected 1.6 kB mRNA and an unexpected 2.6 kB mRNA. In endometria, RTP4 mRNA levels in cyclic ewes remained low, whereas RTP4 mRNA increased from Days 11 to 17 in pregnant ewes. Levels of RTP4 mRNA also increased from Days 15 to 19 in CL and PBL samples from pregnant ewes only. RTP4 mRNA was located in the glandular epithelium, and stratum compactum and caruncular stroma. Ovine glandular epithelial cells were treated with IFNT to determine if IFNT alone could induce RTP4. IFNT increased RTP4 over 70-fold 1.5 hours after treatment with maximal induction of nearly 300-fold above values observed in non-treated controls 6 hours after treatment. These results indicate that RTP4 mRNA levels are induced in the ovine endometrium, PBL, and CL by IFNT during early pregnancy and in cell culture in response to IFNT. If RTP4 expression affects G-protein-coupled receptor function it may be important for establishment of pregnancy in domestic ruminants.
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