Sonic hedgehog signalling from foregut endoderm patterns the avian nasal capsule.
Morphogenesis of the facial skeleton depends on inductive interactions between cephalic neural crest cells and cephalic epithelia, including the foregut endoderm. We show that Shh expression in the most rostral zone of the endoderm, endoderm zone I (EZ-I), is necessary to induce the formation of the ventral component of the avian nasal capsule: the mesethmoid cartilage. Surgical removal of EZ-I specifically prevented mesethmoid formation, whereas grafting a supernumerary EZ-I resulted in an ectopic mesethmoid. EZ-I ablation was rescued by Shh-loaded beads, whereas inhibition of Shh signalling suppressed mesethmoid formation. This interaction between the endoderm and cephalic neural crest cells was reproduced in vitro, as evidenced by Gli1 induction. Our work bolsters the hypothesis that early endodermal regionalisation provides the blueprint for facial morphogenesis and that its disruption might cause foetal craniofacial defects, including those of the nasal region.
Benouaiche
Laurence
L
Evolution des Régulations Endocriniennes, CNRS UMR 5166, Muséum National d'Histoire Naturelle, Paris, France.
Gitton
Yorick
Y
Vincent
Christine
C
Couly
Gérard
G
Levi
Giovanni
G
D000818:Animals; D019521:Body Patterning; D002645:Chickens; D004625:Embryo, Nonmammalian / Q000196:embryology / Q000378:metabolism; D004707:Endoderm / Q000196:embryology* / Q000378:metabolism*; D041981:Gastrointestinal Tract / Q000196:embryology* / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D053823:Hedgehog Proteins / Q000235:genetics / Q000378:metabolism*; D009297:Nasal Mucosa / Q000378:metabolism*; D009432:Neural Crest / Q000196:embryology / Q000378:metabolism; D009666:Nose / Q000201:enzymology*; D015513:Oncogene Proteins / Q000378:metabolism; D011784:Quail; D015398:Signal Transduction; D015534:Trans-Activators / Q000378:metabolism; D000071676:Zinc Finger Protein GLI1
D053823:Hedgehog Proteins; D015513:Oncogene Proteins; D015534:Trans-Activators; D000071676:Zinc Finger Protein GLI1