The embryonic DPPA3 gene stimulates the expression of pregnancy-related genes in bovine endometrial cells.

Extracellular vesicles (EV) released by cells contain mRNAs, microRNAs, long noncoding RNAs, lipids, and proteins, playing crucial roles in cell-cell communication. Although full-length mRNA transcripts have been documented in EV secreted by cancer cells, there are no reports on full transcripts secreted by embryos. Our study aimed to identify EV mRNAs in the culture medium of bovine embryos and investigate their roles in embryo-maternal communication. Following the isolation of EV from in vitro fertilization media samples and RNA sequencing, we identified a full mRNA transcript of DPPA3, known to play an essential role in embryo development. To examine the role of DPPA3 in embryo-maternal communication, an in vitro transcribed mRNA of DPPA3 was transfected into bovine endometrial epithelial cells. Transfected and control cells were subsequently analyzed with RNA sequencing and proteomics to assess the effects of DPPA3 on gene expression. A total of 24 genes were found to be upregulated, and 1 gene was downregulated (false discovery rate <0.01) following DPPA3 transfection, many with known functions in pregnancy recognition. Proteomic analysis revealed 28 differentially expressed proteins, with 17 upregulated and 11 downregulated. Two proteins, ISG15 and MX1, overlapped with the differentially expressed mRNAs. To mimic the natural transfer of EV from embryos to endometrial cells, we performed coculture with d-8 blastocysts or supplemented the cells with embryo-conditioned culture medium. DPPA3 presence was detected in endometrial cells exposed to embryo-conditioned medium after just 30 min. Overall, our study highlights the significant role of EV in cell-cell communication through mRNA signaling from the embryo to the mother.