MicroRNAs (miRNAs) are presented in the uterine lumen of many mammals, and in vitro experiments have determined that several miRNAs are important for the regulation of endometrial and trophoblast functions. Our aim was to identify and contrast the miRNAs present in extracellular vesicles (EVs) in the uterine lumen fluid (ULF) at the onset of attachment in cattle pregnancies (gestation d 18) initiated by artificial insemination (AI) or by the transfer of an in vitro-produced blastocyst (IVP-ET). A third group had no conceptus after the transfer of an IVP embryo. The abundance of 263 annotated miRNAs was quantified in the EVs collected from ULF. There was an increase in the transcript abundance of 20 miRNAs in the ULF EVs from the AI pregnant group, while 4 miRNAs had a lower abundance relative to the group not containing a conceptus. Additionally, 4 miRNAs were more abundant in ULF EVs in the AI pregnant group relative to IVP-ET group (bta-mir-17, bta-mir-7-3, MIR7-1, MIR18A). Specific miRNAs in the ULF EVs were co-expressed with messenger RNAs expressed in extra-embryonic tissues and endometrium, including genes that are known to be their targets. The results provide biological insights into the participation of miRNAs in the regulation of trophoblast proliferation and differentiation, as well as in endometrium receptivity. The knowledge that in vitro cultured embryos can contribute to the altered abundance of specific miRNAs in the uterine lumen can lead to the development of corrective approaches to reduce conceptus losses during the first month of pregnancy in cattle.

中文翻译：

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通过人工授精或体外产生的胚胎移植引发的牛 (Bos taurus) 妊娠中子宫腔液体中 microRNA 成分的改变


MicroRNA (miRNA) 存在于许多哺乳动物的子宫腔中，体外实验已确定几种 miRNA 对于子宫内膜和滋养层功能的调节很重要。我们的目的是鉴定和对比通过人工授精 (AI) 或通过移植胚胎开始的牛妊娠（妊娠第 18 天）附着开始时子宫腔液 (ULF) 中的细胞外囊泡 (EV) 中存在的 miRNA。体外产生的囊胚（IVP-ET）。第三组在IVP胚胎移植后没有受孕。在从 ULF 收集的 EV 中对 263 个带注释的 miRNA 的丰度进行了定量。 AI妊娠组的ULF EV中20个miRNA的转录丰度增加，而4个miRNA的转录丰度相对于不包含孕体的组较低。此外，相对于 IVP-ET 组，AI 妊娠组 ULF EV 中的 4 个 miRNA（bta-mir-17、bta-mir-7-3、MIR7-1、MIR18A）更丰富。 ULF EV 中的特定 miRNA 与胚胎外组织和子宫内膜中表达的信使 RNA 共表达，包括已知的靶基因。这些结果为 miRNA 参与滋养层增殖和分化以及子宫内膜容受性的调节提供了生物学见解。体外培养的胚胎可能会导致子宫腔中特定 miRNA 丰度的改变，这一知识可以导致纠正方法的开发，以减少牛怀孕第一个月期间的概念损失。