Girardet Laura, Kamath Neha, Dufort Daniel
Department of Obstetrics and Gynecology, McGill University, Montreal, QC, Canada.
Research Institute of the McGill University Health Centre, Child Health and Human Development Program, Montreal, QC, Canada.
Front Cell Dev Biol. 2025 May 19;13:1608976. doi: 10.3389/fcell.2025.1608976. eCollection 2025.
Proper placentation is essential for fetal growth and development in mammals. Nodal signaling is essential to ensure proper embryo development and requires Cripto-1 as a co-receptor. Both factors have been shown to be expressed in the maternal decidua and developing placenta. Notably, a maternal loss of either Nodal or Cripto-1 leads to defective placentation resulting in intrauterine growth restriction and fetal loss. However, the role of Nodal or Cripto-1 in placental development has not been determined.
To better understand the roles of Nodal and Cripto-1 in trophoblast populations, we employed a trophoblast-specific deletion model using Tat-Cre recombinant protein to induce deletion of the floxed Nodal or Cripto-1 genes exclusively in the trophectoderm at the blastocyst stage (TE-KO). Treated embryos were then transferred into the uteri of pseudopregnant mice, and implantation sites were examined at gestational days (d) 8.5 and 10.5. Placental morphology and trophoblast populations were analyzed through histological and molecular marker analysis.
TE-KO of Nodal led to a decrease in the implantation site size and placental thickness, primarily due to a smaller labyrinth area while the junctional zone was increased. Immunostaining revealed an important expansion of PL trophoblast giant cells and decrease of TPBPA spongiotrophoblast/glycogen cells. TE-KO of Cripto-1 also led to smaller implantation sites and reduced placental thickness, but this was attributed to a smaller junctional zone. A decrease in TPBPA spongiotrophoblast cells without affecting glycogen cells was observed. A reduction in MCT1 and syncytiotrophoblasts and an increase in total area of maternal blood sinuses within the labyrinth emphasized its disorganization. Earlier effects of Cripto-1 TE-KO on the trophoblast maintenance were witnessed at d8.5, with a marked reduction in TPBPA cells, reduced trophoblast cell proliferation (PCNA) and increased apoptosis (TUNEL).
The distinct phenotypes observed indicate the different roles Nodal and Cripto-1 play in placental development. This highlights the importance of other TGF-β-dependent and independent pathways involving Cripto-1. Overall, our findings highlight the critical role of Nodal and Cripto-1 in regulating key aspects of placental development, including trophoblast differentiation, cellular specification, and structural organization, promising avenues for future research in placental biology.
正常的胎盘形成对于哺乳动物胎儿的生长发育至关重要。Nodal信号对于确保胚胎正常发育必不可少，且需要Cripto-1作为共受体。这两个因子均已证实在母体蜕膜和发育中的胎盘中表达。值得注意的是，母体中Nodal或Cripto-1的缺失会导致胎盘形成缺陷，进而导致子宫内生长受限和胎儿丢失。然而，Nodal或Cripto-1在胎盘发育中的作用尚未确定。
为了更好地了解Nodal和Cripto-1在滋养层细胞群体中的作用，我们采用了一种滋养层特异性缺失模型，使用Tat-Cre重组蛋白在囊胚期仅诱导滋养外胚层中经基因打靶的Nodal或Cripto-1基因缺失（TE-KO）。然后将处理过的胚胎转移到假孕小鼠的子宫中，并在妊娠第8.5天和10.5天检查着床部位。通过组织学和分子标记分析来分析胎盘形态和滋养层细胞群体。
Nodal的TE-KO导致着床部位大小和胎盘厚度减小，主要是由于迷路区变小而连接区增大。免疫染色显示PL滋养层巨细胞显著增多，TPBPA海绵滋养层/糖原细胞减少。Cripto-1的TE-KO也导致着床部位变小和胎盘厚度减小，但这归因于连接区变小。观察到TPBPA海绵滋养层细胞减少，而糖原细胞未受影响。迷路区内MCT1和合体滋养层减少，母体血窦总面积增加，突出了其结构紊乱。在第8.5天就观察到Cripto-1的TE-KO对滋养层维持的早期影响，TPBPA细胞显著减少，滋养层细胞增殖（PCNA）降低，凋亡增加（TUNEL）。
观察到的不同表型表明Nodal和Cripto-1在胎盘发育中发挥着不同作用。这突出了涉及Cripto-1的其他TGF-β依赖性和非依赖性途径的重要性。总体而言，我们的研究结果突出了Nodal和Cripto-1在调节胎盘发育关键方面的关键作用，包括滋养层分化、细胞特异性和结构组织，为胎盘生物学的未来研究提供了有前景的途径。
