Pre-Implantation Conceptus and Maternal Uterine Communications: Molecular Events Leading to Successful Implantation

Evaluation of the effect of indomethacin and piroxicam administration before embryo transfer on pregnancy rate

AIM

The aim of this study was to evaluate the effect of non-steroidal anti-inflammatory drug (NSAID) administration before embryo transfer (ET) on pregnancy rates in women undergoing in vitro fertilization/intracytoplasmic sperm injection ET.

METHODS

Our study included 255 patients diagnosed with primary or secondary infertility caused by a male or tubal-related factor, endometriosis or unexplained factors. The patients were divided randomly into three groups. Two groups were administered oral piroxicam (10 mg capsules) or 100 mg indomethacin (rectal suppository), respectively, 1-2 h before ET. As a control, the third group did not receive any form of treatment before ET. Basal levels of follicle-stimulating hormone, luteinizing hormone, and level 17β-estradiol on the day of human chorionic gonadotropin administration, the collected and transferred number of embryos, and the number of grade A embryos obtained were determined in all patients.

RESULTS

The implantation, clinical pregnancy, and miscarriage rates of the groups were compared. The clinical pregnancy rate per ET and the implantation rate were 35.2% and 12.15% in the piroxicam group, 31.7% and 10.9% in the indomethacin group, and 32.9% and 12.5% in the control, respectively. The miscarriage rates of groups 1, 2 and 3 were 12%, 11.7% and 11.7%, respectively (P = 0.964). The differences in clinical pregnancy rates among the groups were not statistically significant (P = 0.887). There were also no significant differences in the implantation rates (P = 0.842).

CONCLUSION

These results suggest that NSAID administration before ET has no additional effect on pregnancy outcome in patients undergoing in vitro fertilization.

Intrauterine trophoblast migration: A comparative view of humans and rodents

Trophoblast migration and invasion through the decidua and maternal uterine spiral arteries are crucial events in placentation. During this process, invasive trophoblast replace vascular endothelial cells as the uterine arteries are remodeled to form more permissive vessels that facilitate adequate blood flow to the growing fetus. Placentation failures resulting from either extensive or shallow trophoblastic invasion can cause pregnancy complications such as preeclampsia, intrauterine growth restriction, placenta creta, gestational trophoblastic disease and even maternal or fetal death. Consequently, the use of experimental animal models such as rats and mice has led to great progress in recent years with regards to the identification of mechanisms and factors that control trophoblast migration kinetics. This review aims to perform a comparative analysis of placentation and the mechanisms and factors that coordinate intrauterine trophoblast migration in humans, rats and mice under physiological and pathological conditions.

SOLD1 is expressed in bovine trophoblast cell lines and regulates cell invasiveness

BACKGROUND

Secreted protein of Ly-6 domain 1 (SOLD1), a secretory-type member of the Ly-6 superfamily, is expressed in both fetal and maternal tissues throughout gestation. SOLD1 mRNA is expressed in the endometrium and in trophoblast mononucleate and binucleate cells, suggesting it plays an important role not only in placental architecture at early gestation, but also in remodeling the endometrium at late gestation. Here, we investigate the expression of SOLD1 mRNA and protein in trophoblast cell lines. In addition, we examine the effect of SOLD1 on the invasive ability of trophoblast cells.

METHODS

We measured SOLD1 gene expression in thirteen bovine trophoblast (BT) cell lines by using quantitative reverse transcription PCR (qRT-PCR). SOLD1 protein levels were examined in two cell lines, BT-C and BT-K, by using Western blotting and immunocytochemistry. In addition, we measured the invasive activity of BT cells in the presence or absence of anti-bovine SOLD1 antibodies.

RESULTS

At variable levels, SOLD1 was expressed in all thirteen cell lines; however, expression remained below that of proximal fetal membrane tissue. SOLD1 protein, which was approximately 28 kDa in size, was detected in perinuclear area of the cytoplasm in BT cells. Treatment with anti-bovine SOLD1 antibody had a dose-dependent suppressive effect on the invasiveness of BT-K cell lines.

CONCLUSIONS

The present study is the first to investigate SOLD1 expression in vitro, in trophoblastic cell lines. Our data suggested that SOLD1 is involved in the regulation of the trophoblast invasiveness. Therefore, SOLD1 may play an active and crucial role in mediating communication at the fetomaternal interface.

Proteomic analysis of the sheep caruncular and intercaruncular endometrium reveals changes in functional proteins crucial for the establishment of pregnancy

The expression and regulation of endometrial proteins are crucial for conceptus implantation and development. However, little is known about site-specific proteome profiles of the mammalian endometrium during the peri-implantation period. We utilised a two-dimensional gel electrophoresis/mass spectrometry-based proteomics approach to compare and identify differentially expressed proteins in sheep endometrium. Caruncular and intercaruncular endometrium were collected on days 12 (C12) and 16 (C16) of the oestrous cycle and at three stages of pregnancy corresponding to conceptus pre-attachment (P12), implantation (P16) and post-implantation (P20). Abundance and localisation changes in differentially expressed proteins were determined by western blot and immunohistochemistry. In caruncular endometrium, 45 protein spots (5% of total spots) altered between day 12 of pregnancy (P12) and P16 while 85 protein spots (10% of total spots) were differentially expressed between P16 and C16. In intercaruncular endometrium, 31 protein spots (2% of total spots) were different between P12 and P16 while 44 protein spots (4% of total spots) showed differential expression between C12 and C16. The pattern of protein changes between caruncle and intercaruncle sites was markedly different. Among the protein spots with implantation-related changes in volume, 11 proteins in the caruncular endometrium and six proteins in the intercaruncular endometrium, with different functions such as protein synthesis and degradation, antioxidant defence, cell structural integrity, adhesion and signal transduction, were identified. Our findings highlight the different but important roles of the caruncular and intercaruncular proteins during early pregnancy.

Transcriptional regulation of two conceptus interferon tau genes expressed in Japanese black cattle during peri-implantation period

Interferon tau (IFNT), produced by the mononuclear trophectoderm, signals the process of maternal recognition of pregnancy in ruminants. However, its expression in vivo and its transcriptional regulation are not yet well characterized. Objectives of this study were to determine conceptus IFNT gene isoforms expressed in the bovine uterus and to identify differences in promoter sequences of IFNT genes that differ in their expression. RNA-seq data analysis of bovine conceptuses on days 17, 20, and 22 (day 0  =  day of estrus) detected the expression of two IFNT transcripts, IFNT1 and IFNTc1, which were indeed classified into the IFNT gene clade. RNA-seq and quantitative RT-PCR analyses also revealed that the expression levels of both IFNT mRNAs were highest on day 17, and then decreased on days 20 and 22. Bovine ear-derived fibroblast (EF) cells, a model system commonly used for bovine IFNT gene transcription study in this laboratory, were cotransfected with luciferase reporter constructs carrying upstream (positions -637 to +51) regions of IFNT1 or IFNTc1 gene and various transcription factor expression plasmids including CDX2, AP-1 (Jun) and ETS2. CDX2, either alone or with the other transcription factors, markedly increased luciferase activity. The upstream regions of IFNT1 and IFNTc1 loci were then serially deleted or point-mutated at potential CDX-, AP-1-, and ETS-binding sites. Compared to the wild-type constructs, deletion or mutation at CDX2 or ETS2 binding sites similarly reduced the luciferase activities of IFNT1- or IFNTc1-promoter constructs. However, with the AP-1 site mutated construct, IFNT1- and IFNTc1-reporters behaved differently. These results suggest that two forms of bovine conceptus IFNT genes are expressed in utero and their transcriptional regulations differ.

The effect of embryo presence on the expression of peroxisome proliferator activated receptor (PPAR) genes in the porcine reproductive system during periimplantation

This study was undertaken to determine the effect of the presence of embryos in the uterine horn on peroxisome proliferator activated receptors (PPARs; A, D, G) gene expression in the reproductive tissues of gilts subjected to a surgical procedure. The uterus consisted of one intact horn connected to the uterine corpus and the second horn detached from the uterine corpus but connected with the contiguous ovary. The gilts were hormonally stimulated and divided into two groups: the first group, inseminated (pregnant) and the second group (cyclic), with surgical procedure but not inseminated. The animals of both groups were slaughtered on day 14 of pregnancy or on day 14 of the oestrous cycle, respectively. PPARs mRNA abundance in the endometrium and the corpus luteum (CL) was analysed by quantitative real-time PCR. During pregnancy, PPARA and PPARD μmRNA abundance in the porcine endometrium was significantly higher in the horn containing embryos than in the contralateral horn, where embryos were absent. The endometrial PPARG1 mRNA abundance did not differ between the two horns during pregnancy and the oestrous cycle, but a higher level of the transcript was observed during pregnancy when compared to the oestrous cycle. In the CL, there were no significant differences in PPARA and PPARDμ mRNA abundance between horns in pregnant or cyclic sows. However, there was a significant increase of PPARA and PPARD transcript level in the CL from cyclic compared with pregnant sows. The results of our study suggest that PPARA and PPARD have regulatory functions in early pregnancy, and they indicate that increased levels of endometrial gene expression are correlated with the presence of embryos in the uterine horn. Higher levels of PPARA and PPARD expression in the porcine CL on day 14 of the oestrous cycle than on day 14 of pregnancy suggest that both forms are involved in the regulation of CL functions.

Differential expression of LeY and fucosyltransferase IV correlates with the receptivity of RL95-2 and HEC-1A human uterine epithelial cells

Adhesion molecules expressed on the uterine endometrium are potential receptive markers in embryo implantation. RL95-2 and HEC-1A cell lines represent the high- and low-receptive endometrial epithelium respectively. LeY (Lewis Y) is a difucosylated oligosaccharide highly expressed in the endometrium of some species during implantation. α1, 3 fucosylation of LeY is catalysed by FUT4 (fucosyltransferase IV), the key synthesis enzyme for LeY. We investigated whether the difference in receptivity between the 2 cell lines was related to different expressions of LeY and FUT4. RL95-2 cells expressed a higher level of LeY and FUT4 than HEC-1A cells, as shown by immunofluorescent staining, RT-PCR (reverse transcription-PCR) or Western blotting. FUT4-siRNA (small interfering RNA) transfection down-regulated FUT4 and LeY in RL95-2 cells, and inhibited the adhesion of the embryonic cells (JAR) to RL95-2 cell monolayer. FUT4-cDNA, however, increased the expression of FUT4 and LeY in HEC-1A cells, and increased the adhesion of embryonic cells to HEC-1A cell monolayer. Alterations of LeY level by up- or down-regulation of FUT4 also mediated EGFR (epidermal growth factor receptor)/MAPK (mitogen-activated protein kinase) signalling pathway. To conclude, the expression of LeY and FUT4 correlates with endometrial receptivity, making them potential new markers for the evaluation of endometrial receptivity.

Terminologies for the pre-attachment bovine embryo

There are numerous publications regarding bovine embryos, ranging from descriptions of their appearance and development to emerging techniques in the field of assisted reproductive technology (ART). Concurrently, several specialized terms have been developed to describe the bovine embryo. Many of these terms are simple, some are difficult to understand and use, and others are antiquated and may not be scientifically accurate. For example, use of terms such as syngamy, conception rate, implantation and embryo resorption should be revisited. This review presents a brief overview of current knowledge regarding the pre-attachment period of the bovine embryo and attempts to define the terms. In this process, conventional terminology is presented, and contemporary and novel terms are proposed from a biological perspective.

Expression of GATA1 in the ovine conceptus and endometrium during the peri-attachment period

The transcription factor GATA1 is known to play an essential role in hematopoiesis, but its other roles have not been well characterized. The purpose of this study was to determine relationships between GATA1 and GATA2 and/or GATA3, and to identify their possible functions in ovine development. GATA1 mRNA was found in ovine conceptuses and endometrial epithelial regions of Day 15 (Day 0=day of estrus) cyclic and Days 15, 17, and 21 pregnant ovine uteri. GATA1 mRNA was strongly expressed in conceptuses on Day 21, when trophoblast attachment to the maternal endometrium progressed. Similarly, GATA1 protein expression was relatively high on Day 21. To localize GATA1 mRNA, ovine conceptuses and pregnant uteri were subjected to in situ hybridization on Days 15, 17, and 21, confirming that GATA1 mRNA was expressed in trophoblasts and uterine endometrial epithelial cells in these gestation days. The presence of GATA1 protein was further confirmed by immunohistochemistry. Because high GATA1 expression appeared to coincide with reduced GATA2/3 expression, a potential role of GATA1 was examined through transfection of a mouse Gata1 expression plasmid into bovine trophoblast F3 cells. This over-expression resulted in the down-regulation of endogenous GATA2 transcripts. These observations indicate that GATA1 exists in the ovine conceptus and uterus during the peri-attachment period, and suggest that GATA1 is integral to conceptus and endometrial development through the regulation of GATA2 and possibly other developmentally important genes.

Bovine blastocysts with developmental competence to term share similar expression of developmentally important genes although derived from different culture environments

This study was conducted to investigate the gene expression profile of in vivo-derived bovine embryo biopsies based on pregnancy outcomes after transferring to recipients. For this, biopsies of 30-40% embryos were taken from grade I blastocysts (International Embryo Transfer Society Manual) and the remaining 60-70% of the intact embryos were transferred to recipients. Frozen biopsies were pooled into three distinct groups based on the pregnancy outcome after transferring the corresponding parts, namely those resulting in no pregnancy (NP), pregnancy loss (PL), and calf delivery (CD). Array analysis revealed a total of 41 and 43 genes to be differentially expressed between biopsies derived from blastocysts resulting in NP versus CD and PL versus CD respectively. Genes regulating placental development and embryo maternal interaction (PLAC8) were found to be upregulated in embryo biopsies that ended up with CD. Embryo biopsies that failed to induce pregnancy were enriched with mitochondrial transcripts (Fl405) and stress-related genes (HSPD1). Overall, gene expression profiles of blastocysts resulting in NP and CD shared similar expression profiles with respect to genes playing significant roles in preimplantation development of embryo. Finally, comparing the transcript signatures of in vivo- and in vitro-derived embryos with developmental competence to term revealed a similarity in the relative abundance of 18 genes. Therefore, we were able to present a genetic signature associated with term developmental competence independent of the environmental origin of the transferred blastocysts.

Endometrial expression of IFNAR-1 and oxytocin receptor (OTR) is not improved by prostaglandin analogues when compared to progestagens in ewes

The objective of this study was to investigate differences on the endometrial immunoexpression of type I IFN receptor subunit 1 (IFNAR1) and oxytocin receptor (OTR) during the time of maternal recognition of pregnancy in sheep, when oestrus is synchronized with either prostaglandin analogues (group PG) or conventional progestagens (group P). Plasma progesterone was measured from day 0 to 21 post-coitus (pc) (day 0 = day of oestrus). Immunohistochemistry was performed in samples of uterine horns from pregnant sheep on days 9pc, 13pc, 15pc, 17pc and 21pc to locate IFNAR1 and OTR expression in different endometrial compartments. Mean levels of plasma progesterone were different between treatments, obtaining higher levels in the PG group than in the P group (p < 0.05). Comparing days of pregnancy, IFNAR1 protein expression was different in the luminal epithelium (LE) (p < 0.05), while OTR was different in the LE and in the superficial glandular epithelium (SG) (p < 0.05). Temporal variation on the expression of both proteins from day 9pc to 21pc has been evidenced. IFNAR1 and OTR expression did not show significant differences between treatments. However, the response observed in the endometrium was highly inconsistent when prostaglandin analogues were used. Therefore, the protocol based on prostaglandin analogues still needs to be optimized before being considered as a better alternative to progestagens for oestrous synchronization in sheep.

Expression of endogenous retrovirus-like transcripts in bovine trophoblastic cells

Endogenous retrovirus envelope elements are considered to participate in trophoblastic cell fusion and multinucleate cell formation in humans, mice, and sheep. However, there is limited information about their roles in the ruminant placenta.

OBJECTIVES

We explore and identify the endogenous retrovirus envelope element genes expressed in bovine trophoblasts.

METHODS

The NCBI UniGene database (Build #97 Bos taurus) was screened by in silico analysis. After cloning endogenous retrovirus envelope element-like transcript (ERVE), expression profiles were analyzed with quantitative RT-PCR and in situ hybrizaidation.

RESULTS

Two UniGene clusters, UniGene ID: Bt.68042 and Bt.85243, were detected, and ERVE-A gene was cloned. Weak expression of this gene was first detected on Day 20 of gestation, and the intensity of its expression increased up to Day 70 of gestation. The intensity of its expression was maintained throughout gestation in the placenta, and its specific expression in trophoblastic binucleate cells was confirmed by in situ hybridization.

CONCLUSIONS

bERVE-A has a similar sequence to human syncytin-1, although it lacks an intact envelope sequence, and is specifically expressed in binucleate cells. This is the first evidence that endogenous retrovirus envelope element genes are expressed in bovine binucleate cells.

Progesterone-regulated B4galnt2 expression is a requirement for embryo implantation in mice

OBJECTIVE

To investigate B4galnt2 gene regulation in the female mouse reproductive system (B4galnt2 encodes an enzyme, β1,4-N-acetylgalactosylaminyltransferase II, that catalyzes the addition of GalNAc to glycoproteins via a β1,4 linkage).

DESIGN

Experimental prospective study.

SETTING

Research institute and university.

ANIMAL(S)

Outbred Institute for Cancer Research (ICR) mice.

INTERVENTION(S)

Subcutaneous injection of P/E2; uterine tissues were collected after a 3-day injection period and were collected at different times during pregnancy.

MAIN OUTCOME MEASURE(S)

Gene expression was measured by quantitative real-time polymerase chain reaction after hormonal treatment of ovariectomized mice or pregnant mice. Primary endometrial cell cultivation and a gene promoter assay were used for P regulation analysis. The small interfering RNA (siRNA) technique was used to assess the gene function in embryo implantation in vivo.

RESULT(S)

Animal experiments, a primary endometrial cell cultivation assay, and a gene promoter assay indicated that B4galnt2 is regulated positively by P and negatively by estrogen. B4galnt2 was expressed in uterine tissue at peri-implantation (embryonic day 3.5) along with a sharp increase in placental P production at embryonic day 10.5, and declined as estrogen increased during pregnancy. Using the siRNA in vivo implantation assay, we have proved that B4galnt2 participated in embryonic implantation during pregnancy in mice.

CONCLUSION(S)

This study shows for the first time the expression of B4galnt2 in pregnant mice and its regulation by P. We conclude that the naturally occurring up-regulation of B4galnt2 during pregnancy contributes to normal embryo implantation but not to embryo development.

Do molecular signals from the conceptus influence endometrium decidualization in rodents?

A critical period in establishing pregnancy occurs after the onset of implantation but before placental development. Evidence strongly suggests that abnormalities occurring during this period can result in pregnancy termination or in pre-eclampsia; the latter may lead to small-for-gestational-weight offspring that are likely to be unhealthy. Clearly, events occurring in the endometrium during the implantation process are crucial for proper fetal development and for optimal offspring health. In several mammalian species bi-directional communication between the conceptus and endometrium during implantation is required for successful pregnancy. Although different implantation and placentation modes occur in different mammalian species, common aspects of this bi-directional signaling may exist. The molecular signals from the trophoblast cells of the conceptus, which direct endometrial changes during implantation progression, are well known in some nonrodent species. Currently, we know little about such signaling in rodents during implantation progression, when the endometrium undergoes decidualization. This review focuses on data that support the hypothesis that paracrine signals from the rodent conceptus influence decidualization. Where possible, these findings are compared and contrasted with information currently known in other species that exhibit different implantation modes.

Local and systemic effects of embryos on uterine tissues during early pregnancy in pigs

In the pig, the periimplantation period is critical for successful establishment of pregnancy. We studied the influence of embryos on oxytocin (OT) and progesterone (P(4)) regulated endometrial and myometrial secretion of 1) luteotrophic prostaglandin E(2) (PGE(2)) and 2) luteolytic prostaglandin F(2alpha) and its metabolite (PGFM) on days 12-14 of pregnancy in pigs. We used unilaterally pregnant pigs created by a surgical procedure in which one uterine horn remained intact and the second horn was cut transversely so that part of the horn was detached from the uterine body. The animals were divided into two groups, inseminated gilts (days 12-14 of pregnancy, n=6) and uninseminated cyclic gilts, which were used as controls (days 12-14 of estrous cycle, n=5). Embryos developed only in the patent part of the uterus and not in the occluded horn. The abundance of OTR mRNA was increased in the endometrium and decreased in the myometrium of the gravid uterine horn in the pregnant pigs compared with the non-gravid uterine horn or either uterine horn in the cyclic pigs, indicative of a local effect of the conceptus. The presence of embryos in the uterine horn during the periimplantation period determines endometrial metabolism of PGF(2alpha) and the local response of the endometrium to OT and P(4). OT stimulates PGF(2alpha) secretion and PGFM accumulation in endometrial cultures only from the non-gravid uterine horn and controls PGE(2) secretion from the endometrium and myometrium in the pregnant gilts. The results indicate a more systemic affect of pregnancy on the uterine response to OT and a possibly the local effect of the conceptus in promoting progesterone's inhibition of OT-stimulated PGE(2) secretion and uterine metabolism of PGF(2alpha).

Induction of endogenous interferon tau gene transcription by CDX2 and high acetylation in bovine nontrophoblast cells

Interferon tau gene (IFNT) is expressed only by mononuclear trophectoderm cells in ruminant ungulates. To our knowledge, its epigenetic regulation and interaction with trophectoderm lineage-specific caudal-related homeobox 2 transcription factor (CDX2) have not been characterized. Herein, we studied differences in chromatin structures and transcription of endogenous bovine IFNT in bovine trophoblast BT-1 and CT-1 cells and in nontrophoblast MDBK cells. Transcripts from endogenous IFNT and CDX2 genes were found in BT-1 and CT-1 cells but not in MDBK cells. Chromatin immunoprecipitation study revealed that CDX2 binding sites exist in proximal upstream regions of IFNT (IFN-tau-c1). Endogenous IFNT transcription in BT-1 cells was increased with CDX2 overexpression but was reduced with short interfering RNA specific for the CDX2 transcript. In chromatin immunoprecipitation studies, histone H3K18 acetylation of IFNT was higher in CT-1 cells than in MDBK cells, while histone H3K9 methylation was lower in CT-1 cells than in nontrophoblast cells. In MDBK cells (but not in CT-1 cells), histone deacetylases were bound to IFNT, which was reversed with trichostatin A treatment; treatment with trichostatin A and CDX2 then increased IFNT mRNA levels that resulted from abundant CDX2 mRNA expression. These data provide evidence that significant increase in endogenous IFNT transcription in MDBK cells (which do not normally express IFNT) can be induced through CDX2 overexpression and high H3K18 acetylation, but lowering of H3K9 methylation could also be required for the degree of IFNT transcription seen in trophoblast cells.

Corpus luteum-endometrium-embryo interactions in the dairy cow: underlying mechanisms and clinical relevance

Conception rates of dairy cows are currently declining at an estimated 1% every year. Approximately, 35% of embryos fail to prevent luteolysis during the first three weeks of gestation. Interactions between the corpus luteum, endometrium and embryo are critical to the successful establishment of pregnancy and inadequacies will result in the mortality of the embryo. For example, as little as a one day delay in the post-ovulatory rise of progesterone has serious consequences for embryo development and survival. Recently, we found that LH support, degree of vascularization and luteal cell steroidogenic capacity were not the major factors responsible for this luteal inadequacy, but are nevertheless essential for luteal development and function. Progesterone acting on its receptor in the endometrium stimulates the production of endometrial secretions on which the free-living embryo is dependent. However, their exact composition and effects of inadequate progesterone remains to be determined. The embryo is recognized through its secretion of interferon tau (IFNT), which suppresses luteolytic pulses of prostaglandin F(2 alpha). In the cow, it is most likely that IFNT inhibits oxytocin receptor up-regulation directly and does not require the prior inhibition of oestrogen receptor alpha (ESR1). Unravelling the precise luteal-endometrium and embryo interactions is essential for us to understand pregnancy establishment and development of strategies to reverse the declining fertility of dairy cows.

Endometrial modifications during early pregnancy in bonnet monkeys (Macaca radiata)

The present study was undertaken to investigate endometrial modifications that occur before embryo invasion in bonnet monkeys (Macaca radiata). These changes were analysed in luminal epithelium, glandular epithelium and stroma of endometrial functionalis on Day 6 post ovulation from pregnant and non-pregnant animals (n = 4 each) by transmission electron microscopy. Distinct features (i.e. loss of columnar shape by epithelial cells, changes in mitochondrial size and diffused apicolateral gap junctions) were observed in the luminal and glandular epithelium in pregnant animals. Stromal compaction was also observed in pregnant animals. Further, immunogold localisation studies demonstrated significantly higher expression (P < 0.05) of oestrogen receptor alpha, an oestrogen-regulated gene, in the glandular epithelium and stroma of the endometrium in pregnant animals compared with non-pregnant animals. Expression of two other genes known to be regulated by oestradiol, namely beta-actin and cyclo-oxygenase-1, were also significantly higher (P < 0.05) in the endometria of pregnant animals. These studies demonstrate marked changes in the endometrium before embryo invasion in bonnet monkeys. These studies also indicate altered oestrogenic activity in the uterine milieu before embryo invasion.

Overexpression of fucosyltransferase VII (FUT7) promotes embryo adhesion and implantation

OBJECTIVE

To investigate the effect of increased fucosyltransferase VII (FUT7) on sialyl Lewis X (sLeX) synthesis and their impact on embryo implantation.

DESIGN

Cell and animal study.

SETTING

Liaoning Provincial Core Lab of Glycobiology and Glycoengineering, Department of Biochemistry and Molecular Biology, Dalian Medical University.

ANIMAL(S)

Adult female mice of Kunming species.

INTERVENTION(S)

A pIRES2-EGFP-FUT7 expression plasmid containing full-length human FUT7 cDNA was constructed and transiently transfected into RL95-2 or injected into the uteri of early pregnant mice. Control subjects received the mock pIRES2-EGFP or anti-sLeX antibody.

MAIN OUTCOME MEASURE(S)

The expression of FUT7 and sLeX was detected by reverse transcriptase polymerase chain reaction (RT-PCR) and indirect immunofluorescence. The embryo adhesion rate was assayed in vitro with the cocultured RL95-2 and JAR implantation model. In vivo embryo implantation was investigated using a mouse model.

RESULT(S)

Expression of FUT7 was significantly increased after transfection of pIRES2-EGFP-FUT7 into RL95-2 cells compared with the parental control and mock vector transfectants, as demonstrated by fluorescent microscopy and RT-PCR. Expression of sLeX was also increased in FUT7 overexpressers, as detected by indirect immunofluorescence. Consistent with the elevated expression of FUT7 and sLeX, embryo adhesion rate and embryo implantation competence were significantly increased (P<.01) in both in vitro and in vivo models.

CONCLUSION(S)

Overexpression of FUT7 up-regulates sLeX synthesis and enhances sLeX-mediated embryo implantation.

Analysis of uteroplacental-specific molecules and their functions during implantation and placentation in the bovine

In cattle, the mechanisms underlying implantation and placental development are still unclear. Synepitheliochorial placentation in cattle is noninvasive, and thus generates limited interest in terms of degradation and remodeling of endometrial tissues. The overall purpose of this study was three-fold: (1) to examine the gene circuitry around the implantation window, (2) to understand development of the placenta during the peri-implantation period by using a uteroplacental cDNA microarray, and (3) to study the roles of molecules involved in endometrial remodeling. Bovine trophoblastic binucleate cell-specific molecules, such as pregnancy-associated glycoproteins (PAGs), placental lactogen (PL), and prolactin-related proteins (PRPs), were markedly expressed in binucleate cells (BNCs) around implantation. The expression of PRP-1 was specific to the caruncular (CAR) area of the gravid uterine horn. Gelatinases (MMP-2 and -9) in association with heparanase may be central to endometrial remodeling. In situ hybridization analyses of PAGs, PRPs, PL, and heparanase suggested that BNCs expressed these molecules simultaneously. Future studies will further investigate the specific roles of these molecules in placentogenesis. The uteroplacental cDNA microarray presented cascades of molecular signatures not only for the endometrium but also for the intricate dialogue at the level of the feto-maternal interface in cattle. Placentome morphogenesis potentially parallels the dynamic multigenic circuitry and regulates the cell cycle in the endometrium. The roles of BNCs and their secreted molecules remain an enigma, particularly with regard to the adhesion process and endometrial remodeling, which is the focus of this study.

Molecular evidence for a critical period in mural trophoblast development in bovine blastocysts

Embryonic and extra-embryonic lineages are separated at the blastocyst stage in the mouse at the onset of implantation but well ahead of implantation in most mammals. To provide information on the development of the trophoblast lineage in late-implanting bovine embryos, we combined the use of molecular markers defining embryonic and extra-embryonic lineages in the mouse with a transcriptomic approach dedicated to the early steps of the elongation process, a characteristic feature of blastocyst development in ruminants. In this study, we present molecular evidence for differences between the cow and the mouse in the programming of trophoblast differentiation. This different programming encompasses: (i) the expression of epiblast specifying genes (Oct-4, Nanog) in bovine trophoblast cells at the onset of elongation, (ii) the transcription of proliferation markers in early elongating blastocysts, (iii) the early detection of trophoblast-specific transcripts related to extra-embryonic tissue's differentiation (Hand1, Ets2, IFN-tau) and (iv) the identification of a new transcript (c12) which displays a reciprocal pattern to that of Oct-4 and Nanog genes in the embryonic cells and for which no equivalent has thus far been found in the mouse. Altogether, these results tended to show that early elongation is a critical transition in bovine trophoblast development.

System B0,+ amino acid transport regulates the penetration stage of blastocyst implantation with possible long-term developmental consequences through adulthood

Amino acid transport system B(0,+) was first characterized in detail in mouse blastocysts over two decades ago. Since then, this system has been shown to be involved in a wide array of developmental processes from blastocyst implantation in the uterus to adult obesity. Leucine uptake through system B(0,+) in blastocysts triggers mammalian target of rapamycin (mTOR) signalling. This signalling pathway selectively regulates development of trophoblast motility and the onset of the penetration stage of blastocyst implantation about 20 h later. Meanwhile, system B(0,+) becomes inactive in blastocysts a few hours before implantation in vivo. System B(0,+) can, however, be activated in preimplantation blastocysts by physical stimuli. The onset of trophoblast motility should provide the physiological physical stimulus activating system B(0,+) in blastocysts in vivo. Activation of system B(0,+) when trophoblast cells begin to penetrate the uterine epithelium would cause it to accumulate its preferred substrates, which include tryptophan, from uterine secretions. A low tryptophan concentration in external secretions next to trophoblast cells inhibits T-cell proliferation and rejection of the conceptus. Suboptimal system B(0,+) regulation of these developmental processes likely influences placentation and subsequent embryo nutrition, birth weight and risk of developing metabolic syndrome and obesity.