Transcriptomic analysis of human endometrial stromal cells during early embryo invasion

During early embryo invasion (48 h after embryo attachment), what functional changes accompany dynamic gene expression alterations in human endometrial stromal cells? In the present study, primary human endometrial stromal cells (phESCs) were cultured. After <i>in vitro</i> decidualization, primary human endometrial stromal cells (phESCs) were cultured with blastocysts for 48 h. During this process, blastocysts attached and invaded the phESCs (embryo-invaded primary human endometrial stromal cells, ehESCs). We performed comprehensive transcriptomic profiling of phESCs (two replicates) and ehESCs (five replicates) and analyzed the differentially expressed gene (DEGs) sets for gene ontology (GO) terms and Kyoto encyclopaedia of genes and genomes (KEGG) pathway enrichment. To analyse potential connectivity patterns between the transcripts in these DEG sets, a protein-protein interaction (PPI) network was constructed using the STRING database. A total of 592 DEGs were identified between phESCs and ehESCs after embryo invasion. Primary human endometrial stromal cells underwent significant transcriptomic changes that occur in a stepwise fashion. Oxidative phosphorylation, mitochondrial organization, and P53 signalling pathways were significantly altered in phESCs after embryo invasion. EP300 may play a key role in regulating transcription <i>via</i> chromatin remodelling to facilitate the adaptive gene expression changes that occur during embryo invasion. Our data identify dynamic transcriptome changes that occur in endometrial stromal cells within 48 h after embryo invasion. The pathways that we found to be enriched in phESCs after embryo invasion (oxidative phosphorylation, mitochondrial organization, and P53 signalling) may represent novel mechanisms underlying embryo implantation, and may illuminate the reasons that some women experience reproductive failure.Key messagesHuman endometrial stromal cells have undergone changes in gene expression regulation and signalling pathways during the embryo invasion.Mitochondrial-oxidative phosphorylation changes in human stromal cells manifested as down-regulation of gene expression in the electron transport chain.TP53 signalling pathway and transcriptional regulator EP300 assist stromal cells to get adaptive changes during embryo invasion phase. Human endometrial stromal cells have undergone changes in gene expression regulation and signalling pathways during the embryo invasion. Mitochondrial-oxidative phosphorylation changes in human stromal cells manifested as down-regulation of gene expression in the electron transport chain. TP53 signalling pathway and transcriptional regulator EP300 assist stromal cells to get adaptive changes during embryo invasion phase.

在胚胎早期侵袭阶段（胚胎附着后48小时），人类子宫内膜基质细胞的功能变化伴随哪些动态基因表达改变？
本研究培养了原代人子宫内膜基质细胞（primary human endometrial stromal cells, phESCs）。经体外（in vitro）蜕膜化处理后，将原代人子宫内膜基质细胞与囊胚共培养48小时，此过程中囊胚附着并侵袭基质细胞，获得胚胎侵袭后的原代人子宫内膜基质细胞（embryo-invaded primary human endometrial stromal cells, ehESCs）。
本研究对phESCs（2个生物学重复）与ehESCs（5个生物学重复）开展全面转录组分析，筛选得到差异表达基因（differentially expressed gene, DEGs）集，并对其进行基因本体（Gene Ontology, GO）功能富集分析与京都基因与基因组百科全书（Kyoto Encyclopedia of Genes and Genomes, KEGG）通路富集分析。为探究该差异基因集内转录本间的潜在调控关联，本研究借助STRING数据库构建了蛋白质相互作用（protein-protein interaction, PPI）网络。
本研究共鉴定得到592个胚胎侵袭前后的差异表达基因。原代人子宫内膜基质细胞的转录组呈现显著的逐步动态变化。胚胎侵袭后，基质细胞的氧化磷酸化、线粒体组织及P53信号通路发生显著改变。EP300可能通过染色质重塑调控转录，从而介导胚胎侵袭过程中的适应性基因表达变化。
本研究明确了胚胎侵袭后48小时内子宫内膜基质细胞发生的动态转录组变化。本研究鉴定出的胚胎侵袭后基质细胞富集通路（氧化磷酸化、线粒体组织及P53信号通路）可能代表胚胎着床的全新调控机制，或可为解释部分女性生殖失败的原因提供新视角。

关键信息：
1. 胚胎侵袭过程中，人子宫内膜基质细胞的基因表达调控与信号通路均发生显著改变。
2. 人基质细胞的线粒体氧化磷酸化通路变化表现为电子传递链相关基因表达下调。
3. TP53信号通路与转录调控因子EP300可协助基质细胞在胚胎侵袭阶段完成适应性变化。