Gene expression patterns associated with dental replacement in the rabbit, a new model for the mammalian dental replacement mechanisms.

Abstract

Unlike many vertebrates with continuous dental replacement, mammals have a maximum of two dental generations. Due to the absence of dental replacement in the laboratory mouse, the mechanisms of the mammalian tooth replacement system are poorly known. In this study, we use the European rabbit as a model for mammalian tooth development and replacement. We provide data on some key regulators of tooth development. We detected the presence of SOX2 in both the replacement dental lamina and the rudimentary successional dental lamina of unreplaced molars, indicating that SOX2 may not be sufficient to initiate and maintain tooth replacement. We showed that Shh does not seem to be directly involved in tooth replacement. The transient presence of the rudimentary successional dental lamina in the molar allowed us to identify genes that could be essential for the initiation or the maintenance of tooth replacement. Hence, the locations of Sostdc1, RUNX2, and LEF1 vary between the deciduous premolar, the replacement premolar, and the molar, indicating possible roles in tooth replacement. According to our observations, initiation and the maintenance of tooth replacement correlate with the presence of LEF1+ cells and the absence of both mesenchymal RUNX2 and epithelial Sostdc1+ cells.