First published online December 21, 2007
Development 135, 205e (2008)
© The Company of Biologists Limited
Sprouty free and long in tooth
Unusually for mammals, rodent incisors grow continuously, fuelled by stem
cells in their mesenchymal and epithelial compartments. Constant abrasion of
the incisor's lingual side (the side facing the tongue), which unlike the
opposite side has no hard enamel covering, maintains its length and shape. But
why is enamel produced asymmetrically? On
p. 377, Gail Martin and
co-workers report that sprouty (Spry) genes, which encode FGF signalling
antagonists, ensure this asymmetrical enamel deposition and prevent the growth
of tusk-like incisors. The researchers show that enamel-producing ameloblasts
develop from stem cells on both sides of the incisors of
Spry4-/- mouse embryos and that an ectopic
epithelial-mesenchymal FGF signalling loop on the lingual side of the incisors
causes this phenotype. Interestingly, ectopic ameloblast formation is
maintained after birth only if the dosage of Spry1 or Spry2
is also reduced. Thus, the researchers suggest, the generation of
differentiated progeny (such as ameloblasts) from stem cell populations can be
differentially regulated in embryos and adults.
Related articles in Development:
- An FGF signaling loop sustains the generation of differentiated progeny from stem cells in mouse incisors
- Ophir D. Klein, David B. Lyons, Guive Balooch, Grayson W. Marshall, M. Albert Basson, Miroslav Peterka, Tomas Boran, Renata Peterkova, and Gail R. Martin
Development 2008 135: 377-385.
[Abstract]
[Full Text]
