基于单细胞测序研究AP-1/FGFR1在单绒毛膜双胎选择性宫内生长受限中的作用

单绒毛膜双胎在相同的遗传背景下出现选择性宫内生长受限（sIUGR）可能与母胎界面中基因表达异常相关。目前研究多以胎盘组织为样本而忽略了细胞异质性。预实验对两例sIUGR胎盘及蜕膜进行单细胞RNA测序，发现双胎的细胞亚群分布及转录特征存在差异。进一步筛选发现FGFR1在绒毛外滋养细胞分化进程上高表达，且大胎表达高于小胎；单细胞靶向开放染色质测序预测小胎的染色质开放区域更易与AP-1转录因子结合。我们推测：AP-1可能调控FGFR1的表达下降引起绒毛外滋养细胞侵袭增殖功能障碍，进而导致sIUGR。本项目拟进一步对sIUGR母胎界面进行单细胞水平多维度分析，阐释细胞亚群基因表达谱及染色质开放程度，明确胎盘FGFR1和AP-1的表达与sIUGR的关系，并通过体外细胞实验验证AP-1调控FGFR1表达影响滋养细胞功能的分子机制。研究结果为sIUGR的病因研究提供新思路。

Since monochorionic twins shared the same genetic background, selective intrauterine growth restriction (sIUGR) may be closely related to the function of trophoblast cells in the maternal-fetal interface. The former studies mostly used placental tissues as samples to investigate pathogenesis mechanisms of sIUGR, while cellular heterogeneity of placenta was ignored. In the preliminary study, we performed single-cell RNA sequencing (sc RNA-seq) in the placenta and decidua of two pairs of sIUGR twins to evaluate the genomic transcription at the cellular level. The results revealed there were differences in the distribution of cell subgroups and gene transcriptional characteristics between larger and smaller fetuses. Further, we found that the FGFR1 gene revealed specific up-expression along the extravillous trophoblast (EVT) developmental pathway by pseudotime analysis, and FGFR1 was much higher expressed in the EVTs of the larger fetuses than that of the smaller ones. Single-cell assay for targeting accessible-chromatin with high-throughput sequencing predicted that AP-1 transcription factors were more prone to bind in the open chromatin region of EVT in smaller fetuses. Thus, we presume that the expression of FGFR1 is negatively regulated by AP-1 transcription factors resulting in the dysfunction of trophoblasts. This project intends to expand the sample size to further conduct a multidimensional analysis of the sIUGR maternal-fetal interface at a single-cell level, revealing the gene expression profile of each cell subgroup and the chromatin accessibility of the maternal-fetal interface. Next, we confirm the relationship between the expression of FGFR1 and AP-1 in the placenta of sIUGR and investigate the mechanism of AP-1 regulating FGFR1 and affecting the function of trophoblasts in vitro cell experiments. Our research will provide new insight into the etiology research of sIUGR.