The endometrial transcriptome transition accompanying acquisition of receptivity to embryo implantation in mice

Receptivity of the uterus is essential for embryo implantation and progression of pregnancy. Acquisition of receptivity involves major molecular and cellular changes in the endometrial lining of the uterus from its non-receptive state at ovulation, to its receptive state four days later. The precise molecular mechanisms underlying this transition remain to be fully characterized. Here, we aimed to generate a comprehensive profile of the uterine transcriptome in the peri-ovulatory and peri-implantation states, and to define the differences between them, in the mouse. High throughput RNA-sequencing was utilized to identify genes and pathways expressed in the endometrium of C57Bl/6 female mice on day 3.5 post-coitum after mating with BALB/c males, compared to the endometrium of unmated estrous females (n=3-4 biological replicates). RNA-sequencing and analysis using Ingenuity Pathway Analysis software revealed that, compared to the endometrium at estrus, 388 genes were differentially expressed in the endometrium on day 3.5 post-coitum (FDR <= 0.05). Several upstream regulators are implicated in the transition to receptivity including several cytokines, steroid hormones, prostaglandin E2, and vascular endothelial growth factor A. The transcriptional changes indicate substantial changes in the uterine immune and vascular systems during the pre-implantation phase, with the functional terms Angiogenesis, Chemotaxis, and Lymphangiogenesis predominating. This analysis confirms that the transcriptome of a receptive uterus is vastly different to the non-receptive uterus and identifies several genes and regulatory pathways not previously associated with implantation. This dataset will serve as a valuable tool and resource for future research on the molecular mechanisms of uterine receptivity. We performed gene expression profiling using RNA-seq of endometrial tissues from estrous (CONT) females and mated (INT) females on day 3.5 post-coitum. There are three other experimental groups (VAS, SVX and SVXVAS) involving endometrial tissues from females mated with surgically modified males. These groups of samples will be used in a separate manuscirpt to elucidate the role of seminal fluid in transcriptomic changes in the uterus at the peri-implantation phase of pregnancy.子宫容受性对于胚胎着床与妊娠进展至关重要。容受性的获得涉及子宫子宫内膜层从排卵时的非容受状态，到四天后转变为容受状态的重大分子与细胞改变。该转变背后的确切分子机制仍有待全面阐明。本研究旨在构建小鼠围排卵期与围着床期子宫转录组的综合图谱，并明确二者之间的差异。我们采用高通量RNA测序（RNA-sequencing）技术，对与BALB/c雄性小鼠交配后第3.5天的C57Bl/6雌性小鼠子宫内膜，与未交配的发情期雌性小鼠子宫内膜进行对比分析（生物学重复数n=3-4），以鉴定其中表达的基因与通路。通过RNA测序以及Ingenuity通路分析（Ingenuity Pathway Analysis）软件进行分析后发现，与发情期子宫内膜相比，交配后第3.5天的子宫内膜中有388个基因存在差异表达（错误发现率（False Discovery Rate, FDR）≤0.05）。多种上游调控因子参与了向容受状态的转变，包括多种细胞因子、类固醇激素、前列腺素E2以及血管内皮生长因子A（vascular endothelial growth factor A）。转录组变化表明，着床前阶段子宫免疫与血管系统发生了显著改变，其中以血管生成（Angiogenesis）、趋化作用（Chemotaxis）和淋巴管生成（Lymphangiogenesis）这几个功能术语为主导。本分析证实，容受性子宫的转录组与非容受性子宫存在极大差异，并鉴定出此前未与着床相关联的多个基因与调控通路。本数据集将作为研究子宫容受性分子机制的宝贵工具与资源。我们通过RNA-seq对发情期（对照组，CONT）雌性小鼠以及交配后第3.5天的交配组（INT）雌性小鼠的子宫内膜组织进行了基因表达谱分析。另有三个实验分组（VAS、SVX及SVXVAS），其样本来自与经过手术改造的雄性小鼠交配的雌性小鼠的子宫内膜组织。这些样本将在另一篇手稿中用于阐明精液在妊娠围着床阶段子宫转录组变化中的作用。