Abstract: 9

STEROID HORMONE AND INTERFERON REGULATE THE EXPRESSION OF A NOVEL GENE IN THE ENDOMETRIUM DURING IMPLANTATION.

Q. Li¹ , M. Zhang¹ , S. Kumar¹ , D. Chen¹ , M.K. Bagchi¹ , I.C. Bagchi¹
Population Council and The Rockefeller University, New York, NY ¹

Implantation, the initiation of the complex interaction between the embryo and the uterus, is regulated by a timely interplay of the steroid hormones, estrogen (E) and progesterone (P), and various growth factors and cytokines. It is believed that these effectors trigger the expression of a unique set of genes in the uterus that in turn control implantation. Using a PCR-based gene expression-screen technique, we isolated a number of genes that are expressed in the uterus at the onset of implantation. Nucleotide sequence analysis identified one of these as a novel gene, which we termed ERG2. Interestingly, ERG2 exhibited marked homology to previously dentified human interferon (IFN)-inducible genes p27 and IF16-16. We observed that in normal pregnant rats, ERG2 mRNA is expressed at low levels on days 1-2 of pregnancy but its expression is markedly enhanced in the uterine epithelium between days 3-5 immediately prior to implantation. Treatment of ovariectomized rats with steroid hormones indicated that the expression of ERG2 mRNA in the uterus is under E regulation. To further analyze the regulation of ERG2 expression in the endometrium by steroid hormones and IFNs, we performed transient transfection experiments in Ishikawa endometrial cells. Our study showed that treatment with IFN or alone markedly increased the level of ERG2 mRNA in Ishikawa cells. E can also induce ERG2 mRNA although the response was weaker relative to that induced by IFNs. A maximal expression of ERG2 mRNA was observed when Ishikawa cells were treated with a combination of IFN or and E. Although the role of ERG2 in implantation remains unclear, these findings indicate that the steroid hormone and IFN pathways may converge to regulate gene expression in the preimplantation uterus.

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