Abstract: 377

PROGESTERONE INDUCES OSTEOPONTIN EXPRESSION IN OVINE ENDOMETRIAL GLANDS.

Greg A. Johnson^{1 *}, Thomas E. Spencer^{1 *}, Robert C. Burghardt^{1 *}, Fuller W. Bazer^{1 *}
Department of Animal Science and Center for Animal Biotechnology and Genomics, Texas A&M University System Health Science Center, College Station, TX ¹

Ovine osteopontin (oOPN) contains a GRGDS sequence that binds to cell surface integrins to promote cell-cell attachment and cell spreading. OPN protein has been localized to lumenal (LE) and glandular epithelium (GE) of both cyclic and pregnant ewes, whereas OPN increases in uterine flushings from pregnant ewes and is present on trophectoderm. This study characterized effects of the estrous cycle and pregnancy on uterine oOPN mRNA expression, and determined if progesterone and/or IFNt regulate OPN mRNA in the ovine uterus. A full-length oOPN cDNA was obtained by screening a Day (D) 15 pregnant ovine endometrial cDNA library with a partial oOPN cDNA. In Exp.1, ewes were hysterectomized on D 1, 3, 5, 7, 9, 11, 13, or 15 of the estrous cycle or D 11, 13, 15, 17 or 19 of pregnancy. In both cyclic and pregnant ewes, in situ hybridization localized OPN mRNA to unidentified immune cells within the stratum compactum of the endometrium. In pregnant ewes, OPN mRNA was also localized to GE. In Exp. 2, D 5 cyclic ewes (n=20) were ovariectomized, fitted with uterine catheters and given daily intrauterine (i.u., D 11-25) injections of protein, and i.m injections (D 5-25) of steroids as follows: 1) 50 mg progesterone + 100 mg control proteins [P-CX]; 2) P + 75 mg ZK112,993 + CX [P+ZK-CX]; 3) P + roIFNt (2×10⁷ AVU) [P-IFN]; or 4) [P+ZK-IFN]. Ewes were hysterectomized on D 25. GE expression of oOPN mRNA did not differ (P>0.10) between P+ZK-CX or P+ZK-IFN treatments. However, OPN mRNA increased (P<0.01) in P-CX and P-IFN ewes. Progesterone alone induced expression of OPN by GE (P-CX vs P-IFN, P>0.10). During peri-implantation, secretory OPN may induce adhesion between LE and trophectoderm to facilitate implantation. USDA-NRICGP 98-35203-6337.

    This abstract is being presented on Monday, August 2 at 3:00 PM at Todd 133.