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Cytokeratin 7 (CK7) is currently regarded as the best marker for trophoblast cells, while CD200 (OX-2), known as ‘tolerance signal’, plays an important role in normal pregnancy. In this study, the status of CD200 expression was investigated in BALB/c × C57BL/6 and BALB/c × BALB/c mating combinations designed as allogeneic and syngeneic murine models of induced embryo resorption, in which the resorption rate was boosted by an i.p. injection of poly (I:C), a synthetic double-stranded RNA. The percentage of CD200⁺ cells in the CK7⁺ cell population (CD200⁺CK7⁺ percentage) and the absolute number of these cells were determined with flow cytometry, using trophoblast cells collected at day 8.5 and day 13.5 of gestation. The potential effect of poly (I:C) on CD200 expression was also evaluated by detecting the CD200⁺CK7⁺ percentage in trophoblast cells incubated in the presence or absence of poly (I:C), in vitro. The distribution pattern of CD200⁺ cells at the feto–maternal interface was evaluated by immunocytochemical examination. When 10⁴ cells were analyzed at day 8.5 of gestation in each case, no significant difference was observed between the poly (I:C)-treated group and the control PBS group either in the CD200⁺CK7⁺ percentage or in the absolute number of these cells. Similar results were observed both in BALB/c × C57BL/6 mice and in BALB/c × BALB/c mice. However, the CD200⁺CK7⁺ percentage was significantly decreased in the poly (I:C)-treated group when evaluated at day 13.5 of gestation. Accordingly, a dramatically elevated rate of embryo resorption was observed at this time point of pregnancy after the administration of poly (I:C). In addition, the CD200⁺CK7⁺ percentage was significantly lower in trophoblast cells incubated with poly (I:C) at a certain concentration, in vitro, while histocytochemical examination showed the CD200⁺ cells mainly scattered in placental tissue adjacent to the interface of the placenta and uterus. This indicates that sufficient expression of the CD200 molecule on CK7⁺ cells at the feto–maternal interface may be necessary for the maintenance of embryos during pregnancy in this rodent model, while poly (I:C) administration may increase embryo resorption, at least partially via direct inhibition of CD200 expression on CK7⁺ cells.

Endocrine gland-derived vascular endothelial growth factor (EG-VEGF) and its receptor genes (PROKR1 (PKR1) and PROKR2 (PKR2)) play an important role in human early pregnancy. We have previously shown that PROKR1 and PROKR2 are associated with recurrent miscarriage (RM) using the tag-SNP method. In this study, we aimed to identify PROKR1 and PROKR2 variants in idiopathic RM patients by genotyping of the entire coding regions. Peripheral blood DNA samples of 100 RM women and 100 controls were subjected to sequence the entire exons of PROKR1 and PROKR2. Significant non-synonymous variant genotypes present in the original 200 samples were further confirmed in the extended samples of 144 RM patients and 153 controls. Genetic variants that were over- or under-represented in the patients were ectopically expressed in HEK293 and JAR cells to investigate their effects on intracellular calcium influx, cell proliferation, cell invasion, cell–cell adhesion, and tube organization. We found that the allele and genotype frequencies of PROKR1 (I379V) and PROKR2 (V331M) were significantly increased in the normal control groups compared with idiopathic RM women (P<0.05). PROKR1 (I379V) and PROKR2 (V331M) decreased intracellular calcium influx but increased cell invasiveness (P<0.05), whereas cell proliferation, cell–cell adhesion, and tube organization were not significantly affected. In conclusion, PROKR1 (I379V) and PROKR2 (V331M) variants conferred lower risk for RM and may play protective roles in early pregnancy by altering calcium signaling and facilitating cell invasiveness.

The chromatoid body (CB) is a specific cloud-like structure in the cytoplasm of haploid spermatids. Recent findings indicate that CB is identified as a male germ cell-specific RNA storage and processing center, but its function has remained elusive for decades. In somatic cells, KH-type splicing regulatory protein (KSRP) is involved in regulating gene expression and maturation of select microRNAs (miRNAs). However, the function of KSRP in spermatogenesis remains unclear. In this study, we showed that KSRP partly localizes in CB, as a component of CB. KSRP interacts with proteins (mouse VASA homolog (MVH), polyadenylate-binding protein 1 (PABP1) and polyadenylate-binding protein 2 (PABP2)), mRNAs (Tnp2 and Odf1) and microRNAs (microRNA-182) in mouse CB. Moreover, KSRP may regulate the integrity of CB via DDX5-miRNA-182 pathway. In addition, we found abnormal expressions of CB component in testes of Ksrp-knockout mice and of patients with hypospermatogenesis. Thus, our results provide mechanistic insight into the role of KSRP in spermatogenesis.

The cryopreservation of human embryos is thought to induce alteration in the glycoprotein matrix and lead to zona change. However, this assumption has been full of controversies till now. The objective of this study was to evaluate the effect of cryopreservation on zona pellucida of human embryos. Fresh (n=106, from 40 patients) and frozen–thawed embryos (n=123, from 40 patients) were obtained from consenting patients who received conventional IVF and ICSI treatment. The birefringence of zona pellucida in human fresh and frozen–thawed embryos was imaged and quantitatively analyzed using polarized light microscopy before embryo transfer. There was no significant difference in retardance and thickness of the zona pellucida multilaminar structure between the two groups. Pregnancy and implantation rates of transferred fresh and frozen–thawed embryos were also compared. No significant difference was found in the rates of clinical pregnancy (47.5 vs 37.5%) and implantation (24.5 vs 23.2%) between the two groups. This study suggests that there is no significant change in the zona pellucida birefringence of human embryos before and after cryopreservation.

Both regulatory T cells and regulatory natural killer (NK) cells may play essential roles in the maintenance of pregnancy. In this study, we show that a significantly high percentage of spontaneous embryo loss was observed in both allogeneic and syngeneic pregnant non-obese diabetic (NOD) mice. The percentage of embryo loss in allogeneic pregnant mice was further increased by the administration of anti-asialo ganglio-N-tetraosylceramide to deplete NK cells, but was decreased by the adoptive transfer of ITGA2⁺ISG20⁺ (CD49b⁺ CD25⁺) NK cells from normal mice. No such trend was observed in syngeneic pregnant NOD mice. The pattern of CXCR4 (specific receptor for CXCL12) expression on NK cells was analyzed and NK-cell migration was confirmed by in vitro and in vivo migratory assays. Since CXCL12 production by murine trophoblast cells was confirmed previously, our findings suggest that the recruitment of peripheral CXCR4-expressing ITGA2⁺ISG20⁺ NK cells into pregnant uteri may be important in the regulation of feto-maternal tolerance.

Japanese eels are commercially valuable species in Asian aquaculture. This study evaluated whether salmon pituitary extract (SPE) or 17β-estradiol (E₂) treatment can induce cytotoxic activity in eel ovarian follicles. Follicular cells died after exposure SPE for 24-h culture in an in vitro culture. Moreover, the E₂ treatment also significantly reduced follicular cell counts. These results reveal that the inhibition of follicular cell numbers by SPE may occur through SPE-induced steroidogenesis. Results of a quantitative PCR analysis indicated that adding E₂ to the culture decreased bcl2 and increased dnmt1 mRNA expression in Japanese eel follicular cells after 24 h. The results of a promoter assay revealed that E₂ significantly increase dnmt1 promoter activity through estrogen receptor-binding site. An in silico analysis predicted several putative transcription factors targeting the bcl2 gene promoter region. Methylation of the bcl2 promoter accounted for the downregulation of bcl2 by E₂-mediated dnmt1. The DNA methylation level of the bcl2 gene was significantly higher in E₂-treated follicular cells than that in the control group. Finally, the E₂-induced hypermethylation pattern of the bcl2 promoter and the reduction in follicular cell numbers were suppressed by adding an MTase inhibitor. Our findings demonstrate that estrogen has a negative effect on the reproductive system of female eels by regulating an epigenetic mechanism during artificial maturation.

The aims were to investigate whether oocyte-secreted growth factors from a high (i.e. rat) and low (i.e. sheep) ovulation rate species could stimulate ³H-thymidine incorporation in granulosa cells (GC) from antral follicles from the same or across species. Denuded oocytes (DO) were co-incubated with GC with or without specific antibodies to growth differentiating factor 9 (GDF9) or bone morphogenetic protein 15 (BMP15). Co-incubations of DO-GC from the same or across species significantly increased thymidine incorporation in GC with increasing numbers of DO. GDF9 immuno-neutralisation reduced thymidine incorporation in rat GC co-incubated with either rat or ovine DO and in ovine GC co-incubated with ovine or rat DO. BMP15 immuno-neutralisation only reduced thymidine incorporation when ovine DO were co-incubated with either ovine or rat GC. Western blotting of oocytes co-incubated with GC identified GDF9 and BMP15 proteins for sheep and GDF9 protein for rats in oocyte lysates and incubation media. With respect to rat BMP15, a promature protein was identified in the oocyte lysate but not in media. Expression levels of GDF9 relative to BMP15 mRNA in DO co-incubated with GC were highly correlated (R ²=0.99) within both species. However, the expression ratios were markedly different for the rat and sheep (4.3 vs 1.0 respectively). We conclude that during follicular development, rat oocytes secrete little, if any, BMP15 and that GDF9 without BMP15 can stimulate proliferation of rat and ovine GC. In contrast, ovine oocytes secrete both BMP15 and GDF9, and both were found to stimulate proliferation in ovine and rat GC.

Cullin 3 (CUL3), a scaffold protein, assembles a large number of ubiquitin ligase complexes, similar to Skp1-Cullin 1-F-box protein complex. Several genetic models have shown that CUL3 is crucial for early embryonic development. Nevertheless, the role of CUL3 in human trophoblast function remains unclear. In this study, immunostaining revealed that CUL3 was strongly expressed in the villous cytotrophoblasts, the trophoblast column, and the invasive extravillous trophoblasts. Silencing CUL3 significantly inhibited the outgrowth of villous explant ex vivo and decreased invasion and migration of trophoblast HTR8/SVneo cells. Furthermore, CUL3 siRNA decreased pro-MMP9 activity and increased the levels of TIMP1 and 2. We also found that the level of CUL3 in the placental villi from pre-eclamptic patients was significantly lower as compared to that from their gestational age-matched controls. Moreover, in the lentiviral-mediated placenta-specific CUL3 knockdown mice, lack of CUL3 resulted in less invasive trophoblast cells in the maternal decidua. Taken together, these results suggest an essential role for CUL3 in the invasion and migration of trophoblast cells, and dysregulation of its expression may be associated with the onset of pre-eclampsia.

Abnormal growth and migration of trophoblast cells is one of the main causes of spontaneous abortion. Eukaryotic translation initiation factor 5A (eIF5A) plays an important role in trophoblast cell growth and migration; however, its underlying mechanism remains largely unknown. Here, we first confirmed that eIF5A knockdown reduced human chorionic trophoblast HTR8 cells viability, proliferation, and migration. Next, we sought to systematically identify the genes regulated by eIF5A and observed changes in the transcriptome profile of eIF5A-knockdown HTR8 cells by RNA-seq analysis. Especially, we found that inhibition of eIF5A reduced both the mRNA and protein levels of methyltransferase-like protein 14 (METTL14). Furthermore, inhibition of METTL14 expression resulted in the reduction of viability, proliferation, and migration of HTR8 cells. In addition, we showed that overexpression of METTL14 rescued the effects of eIF5A knockdown in HTR8 cells. Finally, we revealed that eIF5A and METTL14 expression was decreased in spontaneous abortion samples compared to that in elective-induced abortion samples. Collectively, our study demonstrated that eIF5A plays a crucial role in HTR8 cells via modulation of METTL14 expression and may serve as a novel potential target for spontaneous abortion diagnosis and treatment.