Abstract: 55

ANALYSIS OF THE UPSTREAM SEQUENCES OF THE OVINE ESTROGEN RECEPTOR GENE.

Jo-Ann G.W. Fleming¹ , Thomas E. Spencer^{1 *}, Fuller W. Bazer^{1 *}
Center for Animal Biotechnology and Genomics, Institute for Biosciences and Technology, Texas A&M University System Health Science Center, College Station, TX ¹

Ovine interferon tau (IFN) is the maternal recognition of pregnancy signal in ruminants and suppresses transcription of the estrogen receptor (ER) and oxytocin receptor (OTR) genes in the endometrial luminal epithelium (LE). These actions block OTR expression and release of oxytocin-induced pulses of luteolytic prostaglandin F₂. Type I IFNs induce interferon regulatory factors one (IRF-1) and two (IRF-2) which bind a common IRF DNA element (IRFE) and alter transcription positively and negatively, respectively. Our working hypothesis is that IFN induces IRF-2 which binds to IRFE(s) in the promoter region of the ER gene and suppresses transcription of ER and thus OTR genes. Computer-assisted transcription factor binding site analysis of the 5' flanking region (2.6 kb) of the ovine ER gene identified three putative IRFEs. IFN suppressed transcriptional activity (~4-fold) of a full-length oER promoter-luciferase reporter construct transiently transfected into an immortalized ovine LE cell line. To determine if functional IRFEs were present in the oER gene, electrophoretic mobility shift assays (EMSA) were conducted using putative IRFEs and in vitro transcribed and translated murine IRF-1 and IRF-2. Only the putative IRFE at -1867 nt bound IRF-1 and -2, and these complexes supershifted with either IRF-1 or IRF-2 antibodies. These results support the hypothesis that IFN acts on the LE to induce the production of a IFN-inducible, negative-acting transcription factor such as IRF-2 that silences oER gene transcription. Supported by NIH grant HD32534.

    This abstract is being presented on Sunday, August 1 at 8:00 AM to 10:15 AM at CUB 2nd Floor Ballroom.