Plasticity within the niche ensures the maintenance of aSox2+stem cell population in the mouse incisor.

Abstract

In mice, the incisors grow throughout the animal's life, and this continuous renewal is driven by dental epithelial and mesenchymal stem cells.Sox2is a principal marker of the epithelial stem cells that reside in the mouse incisor stem cell niche, called the labial cervical loop, but relatively little is known about the role of theSox2+stem cell population. In this study, we show that conditional deletion ofSox2in the embryonic incisor epithelium leads to growth defects and impairment of ameloblast lineage commitment. Deletion ofSox2specifically inSox2+cells during incisor renewal revealed cellular plasticity that leads to the relatively rapid restoration of aSox2-expressing cell population. Furthermore, we show thatLgr5-expressing cells are a subpopulation of dentalSox2+cells that also arise fromSox2+cells during tooth formation. Finally, we show that the embryonic and adultSox2+populations are regulated by distinct signalling pathways, which is reflected in their distinct transcriptomic signatures. Together, our findings demonstrate that aSox2+stem cell population can be regenerated fromSox2-cells, reinforcing its importance for incisor homeostasis.