First published online February 20, 2009
Development 136, 602e (2009)
© The Company of Biologists Limited
Less cilia for more bite
In mammals, the number of teeth that form an animal's dentition is strictly
controlled. In mice, the diastema, a toothless region between the incisors and
the molars, contains tooth primordia during embryonic development, but these
primordia are suppressed by apoptosis. On
p. 897, Paul Sharpe and
colleagues surprisingly reveal that a defect in primary cilia results in
increased hedgehog signalling and in the formation of ectopic teeth in the
diastema. Mice mutant for the Ift88/polaris gene, which
encodes a cilia intraflagellar transport protein, display ectopic tooth
formation that correlates with ectopic sonic hedgehog (Shh) activity, and
tissue-specific mutants reveal that polaris is required in the dental
mesenchyme, but not the ectoderm, for normal tooth development. The authors
also demonstrate that mice mutant for the Shh antagonist Gas1 display
increased Shh activity and ectopic diastema teeth. Taken together, these date
indicate that, contrary to prior reports, primary cilia negatively regulate
Shh activity in the diastema mesenchyme, resulting in the suppression of tooth
formation.

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Related articles in Development:
- Primary cilia regulate Shh activity in the control of molar tooth number
- Atsushi Ohazama, Courtney J. Haycraft, Maisa Seppala, James Blackburn, Sarah Ghafoor, Martyn Cobourne, David C. Martinelli, Chen-Ming Fan, Renata Peterkova, Herve Lesot, Bradley K. Yoder, and Paul T. Sharpe
Development 2009 136: 897-903.
[Abstract]
[Full Text]