TITLE: “Building a tooth from transcriptome to tissue morphogenesis”
ABSTRACT: During craniofacial development, the oral epithelium begins as a morphologically homogeneous tissue that gives rise to locally complex structures, including the teeth, salivary glands, and taste buds. How the epithelium is initially patterned and later shaped to generate diverse organ and cell types remains largely unknown. To elucidate the genetic programs that direct the formation of distinct oral epithelial populations, we mapped the transcriptional landscape of embryonic day (E) 12 mouse mandibular epithelia at single cell resolution. Our analysis identified key transcription factors and gene regulatory networks that define different epithelial cell types. By examining the spatiotemporal patterning process along the oral-aboral axis, our results inform a model where the dental field is progressively confined to its position by the formation of the aboral epithelium anteriorly and the non-dental oral epithelium posteriorly. As dental suprabasal cells are enriched with genes related to actomyosin-based motility, we next studied mutant embryos lacking non-muscle myosin II to explore the roles of cellular forces during tooth morphogenesis. We found that myosin II is critical for maintaining cell-cell adhesion and for efficient cellular movement that drives dental epithelial invagination. Together, our results describe the transcriptional regulation during oral epithelial patterning and unveil an actomyosin-based mechanism that promotes tooth invagination.
