Exosome-Associated miRNA Secreted by Endometrium May Stimulate Expression of Adhesion Molecules by Pre-Implantation Embryo

A team of researchers from the University of Valencia in Spain and the Stanford University School of Medicine in the United States has reported data suggesting that miRNAs from the maternal endometrium (image) may act as transcriptomic modifiers of the pre-implantation embryo. In particular, the researchers showed, by microarray profiling, that six of 27 specific, maternal miRNAs were differentially expressed in the human endometrial epithelium during the window of implantation, a brief phase of endometrial receptivity to the blastocyst, and were released into the endometrial fluid. Further investigation revealed that hsa-miR-30d (Homo sapiens miRNA-30d), the expression levels of which were most significantly upregulated, was secreted from the endometrium as an exosome-associated molecule. In rodent experiments, exosome-associated hsa-miR-30d and free hsa-miR-30d were internalized by mouse embryos via the trophectoderm, resulting in an indirect overexpression of genes encoding for certain molecules involved in the murine embryonic adhesion phenomenon, namely, Itgb3, Itga7, and Cdh5. The researchers added that this finding was supported by evidence in vitro: i.e., treating murine embryos with miR-30d resulted in a notable increase in embryo adhesion. As background, the authors noted that during embryo implantation, the blastocyst interacts with and regulates the endometrium, and endometrial fluid secreted by the endometrial epithelium nurtures the embryo. The new data was reported in the September 15, 2015 issue of Development. The article is titled “Hsa-miR-30d, Secreted by the human Endometrium, Is Taken up by the Pre-Implantation Embryo and Might Modify Its Transcriptome.” [Development abstract]
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