PDF(Pubmed)
Abstract：
In the nascent mesoderm, TBXT expression must be precisely regulated to ensure that cells exit the primitive streak and pattern the anterior-posterior axis, but how varying dosage informs morphogenesis is not well understood. In this study, we define the transcriptional consequences of TBXT dosage reduction during early human gastrulation using human induced pluripotent stem cell models of gastrulation and mesoderm differentiation. Multi-omic single-nucleus RNA and single-nucleus ATAC sequencing of 2D gastruloids comprising wild-type, TBXT heterozygous or TBXT null human induced pluripotent stem cells reveal that varying TBXT dosage does not compromise the ability of a cell to differentiate into nascent mesoderm, but instead directly influences the temporal progression of the epithelial-to-mesenchymal transition with wild type transitioning first, followed by TBXT heterozygous and then TBXT null. By differentiating cells into nascent mesoderm in a monolayer format, we further illustrate that TBXT dosage directly impacts the persistence of junctional proteins and cell-cell adhesions. These results demonstrate that epithelial-to-mesenchymal transition progression can be decoupled from the acquisition of mesodermal identity in the early gastrula and shed light on the mechanisms underlying human embryogenesis.
摘要：
在新生的中胚层，Brachyury（TBXT）的表达必须精确调节，以确保细胞离开原始条纹并图案化前后轴，但是不同的剂量如何影响形态发生还没有很好的理解。在这项研究中,我们使用人诱导多能干细胞（hiPSC）原肠胚形成和中胚层分化模型，定义了早期人类原肠胚形成过程中TBXT剂量减少的转录后果。由WT组成的2D类核酸的多体单核RNA和单核ATAC测序，TBXT杂合（TBXT-Het），或TBXT空（TBXT-KO）hiPSC显示，不同的TBXT剂量不会损害细胞分化成新生中胚层的能力，而是直接影响上皮向间充质转化（EMT）的时间进展，而WT首先过渡，其次是TBXT-Het，然后是TBXT-KO。通过将细胞分化为单层形式的新生中胚层，我们进一步说明，TBXT剂量直接影响连接蛋白和细胞-细胞粘附的持久性。这些结果表明，EMT进展可以与早期胃中胚层身份的获得脱钩，并阐明了人类胚胎发生的潜在机制。
