Single-Cell RNA-Sequencing From Mouse Incisor Reveals Dental Epithelial Cell-Type Specific Genes
Yuta Chiba, Kan Saito, Daniel Martı́n, Erich T. Boger, Craig Rhodes, Keigo Yoshizaki, Takashi Nakamura, Aya Yamada, Robert J. Morell, Yoshihiko Yamada, Satoshi Fukumoto
Abstract
Dental epithelial stem cells give rise to four types of dental epithelial cells: inner enamel epithelium (IEE), outer enamel epithelium (OEE), stratum intermedium (SI), and stellate reticulum (SR). IEE cells further differentiate into enamel-forming ameloblasts, which play distinct roles, and are essential for enamel formation. These are conventionally classified by their shape, although their transcriptome and biological roles are yet to be fully understood. Here, we aimed to use single-cell RNA-sequencing to clarify the heterogeneity of dental epithelial cell types. Unbiased clustering of 6,260 single cells from incisors of post-natal day 7 mice classified them into 2 clusters of ameloblast, IEE/OEE, SI/SR and 2 mesenchymal populations. Secretory-stage ameloblasts expressed Amel and Enam were divided into Dspp+ and Ambn+ ameloblasts. Pseudo-time analysis indicated Dspp+ ameloblasts differentiate into Ambn+ ameloblasts. Further, Dspp and Ambn could be stage-specific markers of ameloblasts. Gene Ontology analysis of each cluster indicated potent roles of cell types: OEE in regulation of tooth size and SR in transport of nutrients. Subsequently, we identified novel dental epithelial cell marker genes, namely Pttg1, Atf3, Cldn10, and Krt15. The results not only provided a resource of transcriptome data in dental cells but also contributed to the molecular analyses of enamel formation.