Mouse Endometrium Temporal and Spatial Expression mRNA and MicroRNA Associated With Embryo Implantation.

Embryo implantation is a dynamic physiological process involving morphological and molecular changes in the endometrium during the pre-receptivity, receptivity, and implantation phases. A comprehensive analysis of messenger RNA (mRNA) and microRNA (miRNA) profiles during implantation will likely provide new clues to elucidate the underlying mechanisms governing embryo implantation. We characterized the mRNA and miRNA transcriptomes using next generation sequencing (NGS) of the endometrium 1 day postcoitum (dpc) and 4dpc and the implantation site (IMS) and inter-implantation (IIM) site of the endometrium on 5dpc. Real-time quantitative polymerase chain reaction was performed on selected miRNAs and their predicted target mRNAs to validate their negatively correlated expression. Statistical analysis of the data based on Gene Ontology (GO) group annotation and Kyoto Encyclopedia of Genes and Genomes pathway analysis demonstrated that the genes with significant expression at the IIM site were primarily involved in glucose, protein, and lipoprotein metabolism to provide energy for embryo implantation, while the genes identified at the IMS were involved in RNA functions to produce proteins in support of embryo development and trophoblast invasion. Extracellular matrix (ECM)-receptor interactions between cells and the ECM was the most remarkable event during implantation. The miRNA-mRNA interaction network unraveled the regulatory relationship between miRNAs and mRNAs. Hub miRNAs (mmu-miR-96 and mmu-miR-200b) were identified to target B-cell lymphoma 2 (Bcl-2), Kruppel-like factor 13 (Klf13), and Progesterone receptor (PGR), which are associated with the preparation of the receptive condition or the maintenance of early pregnancy.