Expression of the Hedgehog antagonists Rab23 and Slimb/betaTrCP during mouse tooth development.

The sonic hedgehog signalling peptide has been demonstrated to play an important role in the growth and patterning of several organs including the tooth. Inappropriate activation of Shh signalling in the embryo causes various patterning defects and complex regulation of this pathway is important during normal development. A growing list of diverse antagonists have been identified that restrict Shh signalling in the embryo, however, only Ptc1, Gas1 and Hip1 have been studied during tooth development. We have examined the expression pattern of the putative antagonists Rab23 and Slimb/betaTrCP during early murine odontogenesis and find that these molecules are expressed in the developing tooth. Interestingly, Rab23 demonstrates contrasting expression domains in the incisor and molar dentition during the cap stage, being restricted to the mesenchymal compartment of molar teeth and the epithelium of the enamel knot in incisor teeth. These findings provide the first evidence of distinct regulatory pathways for Shh in teeth of different classes.