Submitted to: Endocrinology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/11/2005
Publication Date: 3/8/2006
Citation: Michael, D.D., Alvarez, I.M., Ocon, O.M., Powell, A.M., Talbot, N.C., Johnson, S.E., Ealy, A.D. 2006. Fibroblast growth factor-2 is expressed by the bovine uterus and stimulates interferon-tau production in bovine trophectoderm. Endocrinology. 147:3571-3579. Interpretive Summary: The early bovine embryo must develop and secrete a factor called interferon-tau (IFN-') in order for pregnancy to be successful. In the present study a growth factor, called fibroblast growth factor-2 (FGF-2) was assayed for in the uterine fluid of cows to see if the cow uterus produced this growth factor. Also, the study investigated whether FGF-2, if present in the cow uterus, might stimulate the growth of the early bovine embryo and if it would also stimulate the production of IFN-' from the early embryo. The study showed that the FGF-2 was present in the uterine fluid of the cow during the early pregnancy period. Pregnancy status did no appear to influence the amount of FGF-2 found in the uterine fluids. The study also showed that FGF-2 may stimulate the growth of the early bovine embryo since it stimulated the growth of a cell line, CT-1 cells, that represents the major tissue component of the early embryo. FGF-2 also was found to stimulate the production of IFN-' in the CT-1 cells in a dose-dependent manner. Therefore, FGF-2 is a uterine-derived factor that modulates bovine embryo growth and production of IFN-'. This knowledge may help improve the efficiency of cattle reproduction.
Technical Abstract: Optimal conceptus development and secretion of the maternal recognition of pregnancy factor, interferon-tau (IFN-'), are prerequisites of pregnancy success in ruminant species. The objectives of this study were to determine if fibroblast growth factor-2 (FGF-2) is present in the uterine lumen and if FGF-2 supplementation to a bovine trophectoderm cell line (CT-1 cell) affected cell proliferation and IFN-' mRNA and protein abundance. Using Western blot analysis, FGF-2 protein of the appropriate molecular mass was detected in uterine luminal flushes derived from pregnant and non-pregnant ewes at d 15 post-estrus. Pregnancy status did not appear to influence FGF-2 abundance in flushes. Supplementing CT-1 cells with boFGF-2 significantly (P<0.05) increased the incorporation of [3H]-Thymidine into DNA. Bovine FGF-2 supplementation also increased IFN-' secretion from CT-1 cells, as determined by measuring antiviral activity in medium. When data were normalized to account for variations in cell number, a significant (P<0.01) dose-dependent increase in IFN-' concentration in medium was detected when comparing controls (2,836 ± 439 IU/ml) to cells supplemented with 0.1 (4,481 ± 629 IU/ml), 1 (4,565 ± 557 IU/ml), 10 (13,055 ± 1,723 IU/ml), or 100 (21,574 ± 3,853 IU/ml) ng/ml boFGF-2. Abundance of IFN-' mRNA in CT-1 cells (assessed by Real-Time RT-PCR) likewise was significantly (P<0.01) increased following exposure to 1 (2.2 ± 0.1 fold effect), 10 (8.2 ± 1.0 fold effect), or 100 (17.3 ± 1.7 fold effect) ng/ml boFGF-2 when compared with control values (1.3 ± 0.1 fold effect). In summary, FGF-2 is present in the uterine lumen during early pregnancy, and FGF-2 acts to regulate bovine trophectoderm proliferation and IFN-' transcription during the peri-implantation period. These observations substantiate claims that uterine- and conceptus-derived factors play an active role in modulating ruminant conceptus development and IFN-' expression during early pregnancy.