Effect of depletion of TCF23 on myometrium transcriptome profile during late pregnancy

TCF23 is a basic-helix-loop-helix transcription factor lacking a DNA binding domain with a C-terminal mediated inhibitory action. Tcf23 was significantly induced by progesterone but not estradiol in vitro and in vivo. To evaluate the biological role of Tcf23, we generated the Tcf23 knockout mouse. Although pregnant Tcf23 KO mice were able to maintain gestation until full term, a considerable proportion of KO females experienced delayed parturition, dystocia, and reduced litter outcomes, with a high incidence of resorption and fetal lethality. Morphological analysis of the pregnant uterus revealed aberrant disruption of both circular and longitudinal myometrial layers and disarrayed extracellular matrix at the conceptus sites in the KO mice. Transcriptome profile analysis of the KO myometrium demonstrated disruptions in cell adhesion, extracellular matrix (ECM), and gap junction signaling, indicating the crucial role of TCF23 in myometrial remodeling and preparation for contractility during late pregnancy. Altogether, our research highlights a novel cause for labor dysfunction mediated by loss of Tcf23 activity in murine uterine tissue. Overall design: To investigate the function of TCF23 in the myometrium contraction, we generated TCF23 knockout mice by CRISPR/Cas9 technology. We then isolated the myometrium tissue from pregnant mice at gestational day 19 and performed RNA-seq of 3 different animals of each genotype. We conducted comparative gene expression profiling by analyzing data obtained from RNA-seq.

TCF23（TCF23）是一类缺乏DNA结合结构域的碱性螺旋-环-螺旋转录因子，其抑制活性由C端结构域介导。体外及体内实验均表明，孕酮可显著诱导Tcf23的表达，而雌二醇则无此调控作用。为探究Tcf23的生物学功能，我们通过CRISPR/Cas9技术构建了Tcf23基因敲除小鼠（knockout mouse, KO）。尽管Tcf23 KO孕鼠可维持妊娠至足月，但相当比例的KO雌性小鼠出现分娩延迟、难产及产仔结局不佳的情况，且胚胎吸收与胎儿致死率显著升高。对妊娠子宫的形态学分析显示，KO小鼠着床位点处的子宫肌层环形与纵行肌层均出现异常断裂，细胞外基质（extracellular matrix, ECM）排列紊乱。对KO小鼠子宫肌层的转录组谱分析结果表明，细胞黏附、细胞外基质及间隙连接信号通路均存在表达异常，这提示TCF23在妊娠晚期子宫肌层重塑及收缩功能准备过程中扮演关键角色。

综上，本研究揭示了小鼠子宫组织中Tcf23活性缺失所介导的分娩功能障碍这一全新诱因。

整体实验设计：为探究TCF23在子宫肌层收缩中的功能，我们通过CRISPR/Cas9技术构建了TCF23基因敲除小鼠。随后，我们于妊娠第19天从孕鼠体内分离子宫肌层组织，对两种基因型各3只实验动物的样本开展RNA测序（RNA-seq）。通过分析RNA-seq所得数据，我们完成了对比基因表达谱分析。