Specific trophoblast transcripts transferred by extracellular vesicles affect gene expression in endometrial epithelial cells and may have a role in embryo-maternal crosstalk

Background

Successful establishment of pregnancy hinges on appropriate communication between the embryo and the uterus prior to implantation, but the nature of this communication remains poorly understood. Here, we tested the hypothesis that the endometrium is receptive to embryo-derived signals in the form of RNA.

Methods

We have utilized a non-contact co culture system to simulate the conditions of pre implantation environment of the uterus. We bioorthogonally tagged embryonic RNA and tracked the transferred transcripts to endometrium. Transferred transcripts were separated from endometrial transcripts and sequenced. Changes in endometrial transcripts were quantified using quantitative PCR.

Results

We show that three specific transcripts are transferred to endometrial cells. We subsequently demonstrate a role of extracellular vesicles (EVs) in this process, as EVs obtained from cultured trophoblast spheroids incubated with endometrial cells induced down-regulation of all the three identified transcripts in endometrial cells.

Finally, we show that EVs/nanoparticles captured from conditioned culture media of viable embryos as opposed to degenerating embryos induce ZNF81 down-regulation in endometrial cells, hinting at the functional importance of this intercellular communication.

Conclusion

Ultimately, our findings demonstrate the existence of an RNA-based communication which may be of critical importance for the establishment of pregnancy.

Construction and Quantitative Validation of Chicken CXCR4 Expression Reporter

Site directional migration is an important biological event and an essential behavior for latent migratory cells. A migratory cell maintains its motility, survival, and proliferation abilities by a network of signaling pathways where CXCR4/SDF signaling route plays crucial role for directed homing of a polarized cell. The chicken embryo due to its specific vasculature modality has been used as a valuable model for organogenesis, migration, cancer, and metastasis. In this research, the regulatory regions of chicken CXCR4 gene have been characterized in a chicken hematopoietic lymphoblast cell line (MSB1). A region extending from -2000 bp upstream of CXCR4 gene to +68 after its transcriptional start site, in addition to two other mutant fragments were constructed and cloned in a promoter-less reporter vector. Promoter activity was analyzed by quantitative real-time RT-PCR and flow cytometry techniques. Our findings show that the full sequence from -2000 to +68 bp of CXCR4 regulatory region is required for maximum promoter functionality, while the mutant CXCR4 promoter fragments show a partial promoter activity. The chicken CXCR4 promoter validated in this study could be used for characterization of directed migratory cells in chicken development and disease models.

Perspective: Cooperation of Nanog, NF-κΒ, and CXCR4 in a regulatory network for directed migration of cancer stem cells

Directed cell migration is a crucial mobility phase of cancer stem cells having stemness and tumorigenic characteristics. It is known that CXCR4 plays key roles in the perception of chemotactic gradients throughout the directed migration of CSCs. There are a number of complex signaling pathways and transcription factors that coordinate with CXCR4/CXCL12 axis during directed migration. In this review, we focus on some transcription factors such as Nanog, NF-κB, and Bmi-1 that cooperate with CXCR4/CXCL12 for the maintenance of stemness and induction of metastasis behavior in cancer stem cells.