Jaw transformation with gain of symmetry after Dlx5/Dlx6 inactivation: mirror of the past?
In modern vertebrates upper and lower jaws are morphologically different. Both develop from the mandibular arch, which is colonized mostly by Hox-free neural crest cells. Here we show that simultaneous inactivation of the murine homeobox genes Dlx5 and Dlx6 results in the transformation of the lower jaw into an upper jaw and in symmetry of the snout. This is the first homeotic-like transformation found in this Hox-free region after gene inactivation. A suggestive parallel comes from the paleontological record, which shows that in primitive vertebrates both jaws are essentially mirror images of each other. Our finding supports the notion that Dlx genes are homeotic genes associated with morphological novelty in the vertebrate lineage.
Beverdam
Annemiek
A
Laboratory of Molecular Morphogenesis, National Institute for Cancer Research, Genova, Italy.
Merlo
Giorgio R
GR
Paleari
Laura
L
Mantero
Stefano
S
Genova
Francesca
F
Barbieri
Ottavia
O
Janvier
Philippe
P
Levi
Giovanni
G
D000818:Animals; D000831:Animals, Newborn; D005075:Biological Evolution; D017353:Gene Deletion; D018628:Gene Dosage; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism*; D007568:Jaw / Q000196:embryology* / Q000378:metabolism / Q000473:pathology; D008334:Mandible / Q000002:abnormalities / Q000378:metabolism; D051379:Mice; D009024:Morphogenesis
C501120:Dlx5 protein, mouse; C100597:Dlx6 protein, mouse; D018398:Homeodomain Proteins