Interferon tau (IFNT) regulation, an anti-luteolytic factor produced by conceptuses of the ruminant ungulates, is essential for the maintenance of early pregnancy, but a definitive mechanism for its temporal transcription has not been elucidated. We and others have observed the T-box protein eomesodermin (EOMES) exhibited high mRNA expression in the ovine embryonic trophectoderm; thus, both caudal-relatedhomeobox-2 (CDX2) and EOMES coexist during the early stages of conceptus development. Objective of this study was to examine the effect of EOMES on ovine IFNT gene transcription when evaluated with CDX2, ETS2 and AP1 transcription factors implicated in the control of cell differentiation in the trophectoderm. In this study, quantitatively via reverse transcription-polymerase chain reaction (RT-PCR) analysis between ovine trophoblast cells was initially performed, finding that transcription factors CDX2 and ‘EOMES transcription factor mRNAs’ were specific to trophectoderm cells. These mRNAs were also found in days 15, 17, and 21 ovine conceptuses. Furthermore, human choriocarcinoma JEG3 cells (trophoblast cell line) were cotransfected with an ovine IFNT (-654bp)-luciferase reporter (-654-oIFNT-Luc) construct and several transcription factor expression plasmids. Cotransfection of the reporter construct with CDX2, ETS2 and AP1 increased transcription of -654-oIFNT-Luc by about 11-fold compared with transfection of the construct alone. When cells were initially transfected with EOMES followed by transfection with CDX2, ETS2 and/or AP1, the expression of -654-oIFNT-Luc was decreased. Also, EOMES factor inhibited the stimulatory activity of CDX2 alone. These results suggest that when conceptuses attach to the uterine epithelium, ovine IFNT gene transcription is down-regulated by an increase of EOMES factor expression in the attached ovine trophoblast cells.

Interferon tau (IFNT), produced by the mononuclear trophectoderm, signals the process of maternal recognition of pregnancy in ruminants, but its expression in vivo is not well characterized. Objectives of this study were to determine IFNT gene isoforms expressed in the bovine uterus, and to identify differences in promoter sequences of IFNT genes that differ in their expression. Through the RNA-seq analysis of bovine conceptuses on days 17, 20 and 22 (day 0 = day of estrus), the expression of only two IFNT transcripts, IFNT1 and IFNTc1, were found, which were indeed classified into the IFNT gene clade. IFNT mRNAs were highest on day 17, and then decreased on days 20, and 22, which were also supported by the results of quantitative RT-PCR. Bovine ear-derived fibroblast (EF) cells were then cotransfected with luciferase reporter constructs carrying 5‘-upstream (positions -1000 to +51) regions of IFNT1 or IFNTc1 and various transcription factor expression plasmids. CDX2, either alone or with other Ap-1, ETS2 and/or CREBBP transcription factors, was found to increase luciferase activity approximately 10 and 18 fold more than twice of those cotransfected with bIFNT1, c1-Luc construct. Furthermore, The degree of transcriptional activation by a combination of the AP1, ETS2, CREBBP and/or CDX2 expression vectors was similar to that of CDX2 along plasmid. However, expression patterns of these Luc activity differented. Whereas bIFNTc1-Luc showed lowest antivity had than bIFNT1-Luc reports. Although, lowest antivity had of the bIFNTc1 –Luc report, cotransfected with the bIFNTc1-Luc construct and AP1(JUN) or/and ETS2 expression plasmid, Luc activity was enhanced approximately 2 and 4-fold more than the bIFNT1-Luc. Furthermore, along CDX2 expression factor had high effect on activity of bIFNT1-Luc reporter than the c1 gene in EF cells. These results suggest that two forms of IFNT genes are expressed in utero and their transcriptional regulations differ.

The transcription factor, early growth response protein 1 (EGR1), act as immediate early response genes to control various cellular and reproductive events. Egr1-deficient female mice show infertility by anovulation resulting from luteinizing hormone-β (LH-β) subunit deficiency. While ovulation, fertilization and embryo development normally occur in Egr1-deficient mice treated with a superovulation regime to rescue LH deficiency, embryo implantation was completely failed. The morphology and ultrastructure of uterine tissues were observed by light and transmission electron microscopy during the peri-implantation period in Egr1-deficient mice. To examine alterations in cellular organelles, the uterine horns were fixed with 2.5% glutaraldehyde and postfixed with 1% osmium tetroxide in PBS. After dehydration and infiltration, the samples were embedded in Epon 812. Semi-thin sections 0.5 μm thick were cut with an ultramicrotome and stained with toluidine blue for light microscopy. Thin sections were cut with a diamond knife of the ultramicrotome and placed on copper grids. The sections were double stained and examined under a transmission electron microscope. The height of luminal epithelial cells was decreased and the polarity was poorly differentiated in the Egr1-deficient comparing to the wild mice. The abundant mucinous materials were observed in the surface of luminal epithelial cells of the Egr1-deficient. It was confirmed the microarray and real time qPCR data. The luminal epithelial cells of wild mice had many dense lipophilic granules and healthy mitochondria, but not in the Egr1-deficient. It may related to production and secretion of steroid hormones and prostaglandins in the luminal epithelial cells for successful implantation. These results show that Egr1 is a critical transcription factor to fine-tune subcellular morphological and functional changes for the receptive phase of peri-implantation period of uterine tissue in mice.

A fertilized oocyte can get the competence for implantation through cleavage and stage-specific gene expression. These are under the control of autonomous and exogenous regulators including physiological culture condition. Endogenous and exogenous growth factors are considered as critical regulators of cleaving embryos during travel the oviduct and uterus. In this study, an effort was made to evaluate comprehensively the quality of embryos for implantation, grown in media enriched with EGF and PAF. The study evaluated developmental rates on given time, blastulation and hatching rates, and adhesion rates. Developmental rates of blastocyst to the hatching stage were significantly high in PAF treated group compared to the control in a dose-dependent manner but not in EGF group. Implantation rates were significantly high both PAF and EGF in a dose-dependent manner. H7, a PKC inhibitor, blocked the process of hatching of the blastocysts but combined treatment of EGF and PAF enhanced the hatching and implantation of blastocsyts. Based on these results it is suggested that EGF and PAF support acquirement of implantation competence at blastocyst stage through a PKC pathway.