Lhx6 is Required for Crown and Root Formation in Molars

Objectives: LIM-homeobox containing (Lhx) genes encode transcriptional regulators that play critical roles in patterning and differentiation in craniofacial organogenesis and the nervous system. Lhx6 and Lhx8 double knockout mice exhibit cleft palate and molar agenesis. However, little is known about the function of Lhx6 in tooth development.
Methods: In our current study, we generated Lhx6CreER/CreER mice and analyzed serial sagittal sections from PN7 to PN18 using HE staining. We examined the Lhx6 expression pattern by generating Lhx6 Cre-ERT;tdTomato mice.
Results: Mice deficient for Lhx6 developed taurodontism in their molars which characterized by elongated and enlarged pulp chamber, whereas incisors were not affected. Lhx6 expression was detectable in odontoblasts, HERS and alveolar bone in the tooth root furcation area from PN0 to PN14. Lineage tracing of Lhx6+ cells indicates that Lhx6 cells are progenitor cells for odontoblasts, alveolar bone and PDL.
Conclusions: Our results demonstrate that Lhx6 is critical for proper crown and root formation in molars.