Zhang Wen-Qian, Zhao Miao, Huang Ming-Yu, Liu Ji-Long
Cell Physiol Biochem. 2018;50(2):668-678. doi: 10.1159/000494187. Epub 2018 Oct 11.
BACKGROUND/AIMS: Embryo implantation is an essential process for eutherian pregnancy, but this process varies across eutherians. The genomic mechanisms that led to the emergence and diversification of embryo implantation are largely unknown.
In this study, we analyzed transcriptomic changes during embryo implantation in mice and rats by using RNA-seq. Bioinformatics and evolutionary analyses were performed to characterize implantation-associated genes in these two species.
We identified a total of 518 differentially expressed genes in mouse uterus during implantation, of which 253 genes were up-regulated and 265 genes were down-regulated at the implantation sites compared with the inter-implantation sites. In rat uterus, there were 374 differentially expressed genes, of which 284 genes were up-regulated and 90 genes were down-regulated. A cross-species comparison revealed that 92 up-regulated genes and 20 down-regulated genes were shared. The differences and similarities between mice and rats were investigated further at the gene ontology, pathway, network, and causal transcription factor levels. Additionally, we found that embryo implantation might have evolved through the recruitment of ancient genes into uterine expression. The evolutionary rates of the differentially expressed genes in mouse and rat uterus were significantly lower than those of the non-changed genes, indicating that implantation-related genes are evolutionary conserved due to high selection pressure.
Our study provides insights into the molecular mechanisms involved in the evolution of embryo implantation.
背景/目的：胚胎着床是真兽类妊娠的一个重要过程，但这个过程在不同真兽类中有所不同。导致胚胎着床出现和多样化的基因组机制在很大程度上尚不清楚。
在本研究中，我们通过RNA测序分析了小鼠和大鼠胚胎着床期间的转录组变化。进行了生物信息学和进化分析，以表征这两个物种中与着床相关的基因。
我们在小鼠子宫着床期间共鉴定出518个差异表达基因，其中与着床间位点相比，着床位点处有253个基因上调，265个基因下调。在大鼠子宫中，有374个差异表达基因，其中284个基因上调，90个基因下调。跨物种比较显示，共有92个上调基因和20个下调基因。在基因本体、通路、网络和因果转录因子水平上进一步研究了小鼠和大鼠之间的差异和相似性。此外，我们发现胚胎着床可能是通过将古老基因招募到子宫表达中而进化的。小鼠和大鼠子宫中差异表达基因的进化速率显著低于未变化基因的进化速率，表明由于高选择压力，与着床相关的基因在进化上是保守的。
我们的研究为胚胎着床进化所涉及的分子机制提供了见解。
