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Abstract：
Formation of highly unique and complex facial structures is controlled by genetic programs that are responsible for the precise coordination of three-dimensional tissue morphogenesis. However, the underlying mechanisms governing these processes remain poorly understood. We combined mouse genetic and genomic approaches to define the mechanisms underlying normal and defective midfacial morphogenesis. Conditional inactivation of the Wnt secretion protein Wls in Pax3-expressing lineage cells disrupted frontonasal primordial patterning, cell survival and directional outgrowth, resulting in altered facial structures, including midfacial hypoplasia and midline facial clefts. Single-cell RNA sequencing revealed unique transcriptomic atlases of mesenchymal subpopulations in the midfacial primordia, which are disrupted in the conditional Wls mutants. Differentially expressed genes and cis-regulatory sequence analyses uncovered that Wls modulates and integrates a core gene regulatory network, consisting of key midfacial regulatory transcription factors (including Msx1, Pax3 and Pax7) and their downstream targets (including Wnt, Shh, Tgfβ and retinoic acid signaling components), in a mesenchymal subpopulation of the medial nasal prominences that is responsible for midline facial formation and fusion. These results reveal fundamental mechanisms underlying mammalian midfacial morphogenesis and related defects at single-cell resolution.
摘要：
高度独特和复杂的面部结构的形成由负责三维组织形态发生的精确协调的遗传程序控制。然而,管理这些过程的基本机制仍然知之甚少。我们结合了小鼠遗传和基因组方法来定义正常和有缺陷的面部中部形态发生的潜在机制。表达Pax3的谱系细胞中Wnt分泌蛋白Wls的条件失活破坏了额鼻原始模式，细胞存活和定向生长，导致面部结构改变，包括中面部发育不全和中线面部裂隙。单细胞RNA测序揭示了中面部原基间充质亚群的独特转录组学图谱，在条件Wls突变体中被破坏。差异表达基因和顺式调控序列分析发现Wls调节并整合了核心基因调控网络，由关键的中面调控转录因子（包括Msx1，Pax3和Pax7）及其下游靶标（包括Wnt，嘘,Tgfβ和视黄酸信号传导成分），在负责中线面部形成和融合的鼻内侧突起的间充质亚群中。这些结果揭示了哺乳动物面部中部形态发生和单细胞分辨率相关缺陷的基本机制。
