title: FLRT3 as a key player on chick limb development.
abstract: Limb outgrowth is maintained by a specialized group of cells, the apical ectodermal ridge (AER), a thickening of the limb epithelium at its distal tip. It has been shown that fibroblast growth factor (FGF) activity and activation of the Erk pathway are crucial for AER function. Recently, FLRT3, a transmembrane protein able to interact with FGF receptors, has been implicated in the activation of ERK by FGFs. In this study, we show that flrt3 expression is restricted to the AER, co-localizing its expression with fgf8 and pERK activity. Loss-of-function studies have shown that silencing of flrt3 affects the integrity of the AER and, subsequently, its proper function during limb bud outgrowth. Our data also indicate that flrt3 expression is not regulated by FGF activity in the AER, whereas ectopic WNT3A is able to induce flrt3 expression. Overall, our findings show that flrt3 is a key player during chicken limb development, being necessary but not sufficient for proper AER formation and maintenance under the control of BMP and WNT signalling.
authors.affiliation: Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, 2780-156 Oeiras, Portugal. artomas@igc.gulbenkian.pt
authors.forename: Ana Raquel
authors.initials: AR
authors.lastname: Tomás
authors.forename: Ana Catarina
authors.initials: AC
authors.lastname: Certal
authors.forename: Joaquín
authors.initials: J
authors.lastname: Rodríguez-León
mesh_terms: D000818:Animals; D019485:Bone Morphogenetic Proteins / Q000378:metabolism; D002642:Chick Embryo; D003001:Cloning, Molecular; D017931:DNA Primers / Q000235:genetics; D004475:Ectoderm / Q000196:embryology* / Q000378:metabolism / Q000648:ultrastructure; D018274:Electroporation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005121:Extremities / Q000196:embryology*; D005346:Fibroblast Growth Factors / Q000378:metabolism; D005353:Fibronectins / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008855:Microscopy, Electron, Scanning; D008863:Microspheres; D016133:Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology*; D051153:Wnt Proteins / Q000378:metabolism
chemical_list: D019485:Bone Morphogenetic Proteins; D017931:DNA Primers; D005353:Fibronectins; D051153:Wnt Proteins; D005346:Fibroblast Growth Factors; D048049:Extracellular Signal-Regulated MAP Kinases