Expression of Dlx genes during the development of the murine dentition

The mammalian Dir homeobox gene family has been shown to play multiple roles in tooth development, but a detailed comparison of the expression pattern of all members throughout tooth development has been lacking. We provide such an analysis for the six known murine Dir genes. The expression patterns for these genes allow a refinement of previously proposed models for the role of Dir genes in tooth type specification and raise the possibility of roles for subsets of these genes in tooth initiation, morphogenesis (enamel navel formation, enamel knot induction, cervical loop growth), and enamel formation. The relationship of Dir gene expression to their genomic organization suggests coordinate regulation of linked genes at early stages but regulatory differences at later stages.