The ectodermal control in chick limb development: Wnt-7a, Shh, Bmp-2 and Bmp-4 expression and the effect of FGF-4 on gene expression.
We have manipulated the chick limb bud by dorsoventrally inverting the ectoderm, by grafting the AER to the dorsal or ventral ectoderm and by insertion of an FGF-4 soaked heparin bead into the mesoderm. After dorso-ventral reversal of the ectoderm, Wnt-7a expression is autonomous from an early stage of limb development in the original dorsal ectoderm. Exogenous FGF-4 causes ectopic Wnt-7a expression and induces ectopic Shh. In addition, exogenous FGF-4 increases the thickness of cartilages and also shortens them, and both Bmp-2 and Bmp-4 may mediate this effect. The ectoderm outside the AER can regulate not only the dorso-ventral polarity of the underlying mesenchyme cells but also the cartilage formation, and both Bmp-2 and Bmp-4 may mediate this control.
Akita
K
K
Department of Anatomy and Developmental Biology, University College, London, UK. k.akita2@med.tmd.ac.jp
Francis-West
P
P
Vargesson
N
N
D000818:Animals; D030161:Avian Proteins; D019521:Body Patterning / Q000187:drug effects; D055396:Bone Morphogenetic Protein 2; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins / Q000235:genetics*; D002356:Cartilage / Q000187:drug effects / Q000196:embryology; D002642:Chick Embryo; D004475:Ectoderm / Q000187:drug effects / Q000378:metabolism; D051519:Fibroblast Growth Factor 4; D005346:Fibroblast Growth Factors / Q000494:pharmacology*; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D053823:Hedgehog Proteins; D017403:In Situ Hybridization; D018878:Limb Buds / Q000187:drug effects / Q000196:embryology* / Q000378:metabolism* / Q000601:surgery; D011506:Proteins / Q000235:genetics*; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000494:pharmacology*; D013997:Time Factors; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; D051153:Wnt Proteins
D030161:Avian Proteins; D055396:Bone Morphogenetic Protein 2; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins; D051519:Fibroblast Growth Factor 4; D053823:Hedgehog Proteins; D011506:Proteins; D011518:Proto-Oncogene Proteins; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; C490509:WNT7A protein, Gallus gallus; D051153:Wnt Proteins; D005346:Fibroblast Growth Factors