Department of Pediatrics, University of Chicago, Chicago, IL 60637.
Department of Pathology, University of Chicago, Chicago, IL 60637.
Proc Natl Acad Sci U S A. 2020 Jul 7;117(27):15712-15723. doi: 10.1073/pnas.1914167117. Epub 2020 Jun 19.
The mechanisms used by embryos to pattern tissues across their axes has fascinated developmental biologists since the founding of embryology. Here, using single-cell technology, we interrogate complex patterning defects and define a Hedgehog (Hh)-fibroblast growth factor (FGF) signaling axis required for anterior mesoderm lineage development during gastrulation. Single-cell transcriptome analysis of Hh-deficient mesoderm revealed selective deficits in anterior mesoderm populations, culminating in defects to anterior embryonic structures, including the pharyngeal arches, heart, and anterior somites. Transcriptional profiling of Hh-deficient mesoderm during gastrulation revealed disruptions to both transcriptional patterning of the mesoderm and FGF signaling for mesoderm migration. Mesoderm-specific / double-mutants recapitulated anterior mesoderm defects and Hh-dependent GLI transcription factors modulated enhancers at FGF gene loci. Cellular migration defects during gastrulation induced by Hh pathway antagonism were mitigated by the addition of FGF4 protein. These findings implicate a multicomponent signaling hierarchy activated by Hh ligands from the embryonic node and executed by FGF signals in nascent mesoderm to control anterior mesoderm patterning.
胚胎在其轴上组织模式的机制自胚胎学创立以来一直令发育生物学家着迷。在这里,我们使用单细胞技术探究复杂的模式缺陷,并定义了一个 Hedgehog(Hh)-成纤维细胞生长因子(FGF)信号轴,该信号轴在原肠胚形成期间对于前中胚层谱系发育是必需的。Hh 缺陷的中胚层的单细胞转录组分析显示,前中胚层群体存在选择性缺陷,最终导致前胚胎结构的缺陷,包括咽弓、心脏和前体节。原肠胚形成期间 Hh 缺陷的中胚层的转录谱分析显示,中胚层的转录模式以及中胚层迁移的 FGF 信号都受到了干扰。中胚层特异性/双突变体再现了前中胚层缺陷,并且 Hh 依赖性 GLI 转录因子在 FGF 基因座调节增强子。由 Hh 途径拮抗作用诱导的原肠胚形成期间的细胞迁移缺陷可以通过添加 FGF4 蛋白来减轻。这些发现表明,由胚胎节点的 Hh 配体激活的多成分信号级联反应,并由新生中胚层中的 FGF 信号执行,用于控制前中胚层模式形成。