Biosensor capability of the endometrium is mediated in part, by altered miRNA cargo from conceptus-derived extracellular vesicles.
We tested the hypothesis that the biosensor capability of the endometrium is mediated in part, by the effect of different cargo contained in the extracellular vesicles secreted by the conceptus during the peri-implantation period of pregnancy. We transferred Bos taurus taurus embryos of different origin: In vivo (high developmental potential (IV)), in vitro (intermediate developmental potential (IVF)), or cloned (low developmental potential (NT)), into Bos taurus indicus recipients. Extracellular vesicles (EVs) recovered from Day 16 conceptus conditioned medium were characterized and their microRNA (miRNA) cargo sequenced alongside RNA sequencing of their respective endometria. There were substantial differences in the endometrial response to in vivo Vs in vitro and in vivo Vs cloned conceptuses (1153 and 334DEGs respectively) with limited differences between in vitro Vs cloned conceptuses (36 DEGs). miRNA cargo was similar between all three groups (426 common cargo) differences between in vivo and cloned (8 miRNAs), and in vivo and in vitro (6 miRNAs) observed. Treatment of endometrial epithelial cells with mimic or inhibitors for miR-128 and miR-1298 changes to the proteomic content of target cells (96, and 85 respectively) of which mRNAs are altered in the endometrium in vivo (PLXDC2, COPG1, HSPA12A, MCM5, TBL1XR1, and TTF). In conclusion, we have determined that the biosensor capability of the endometrium is mediated in part, by its response to different EVs miRNA cargo produced by the conceptus during the peri-implantation period of pregnancy. SIGNIFICANCE STATEMENTDuring the peri-implantation period of pregnancy in mammals, the endometrium acts as a biosensor for the developmental competency of the embryo. However, the mechanism by which biosensor capability of the endometrium is established, remains elusive. In this study, we show that embryos of different developmental competencies have distinct microRNA cargo contained in their extracellular vesicles (EVs). Exposure of the endometrium to these conceptuses alters the transcriptional response of the endometrium during the process of pregnancy recognition. This differential response is mediated in part, by the delivery and action of the these differentially abundant microRNAs into EVs. Here we propose differences in EV-mediated miRNA cargo are responsible in part for this biosensor capability of the endometrium.