title: An essential role for zebrafish Fgfrl1 during gill cartilage development.
abstract: The vertebrate craniofacial skeleton develops via a complex process involving signaling cascades in all three germ layers. Fibroblast growth factor (FGF) signaling is essential for several steps in pharyngeal arch development. In zebrafish, Fgf3 and Fgf8 in the mesoderm and hindbrain have an early role to pattern the pouch endoderm, influencing craniofacial integrity. Endodermal FGF signaling is required for the differentiation and survival of postmigratory neural crest cells that form the pharyngeal skeleton. We identify a novel role for zebrafish Fgf receptor-like 1a (Fgfrl1a) that is indispensable during gill cartilage development. We show that depletion of Fgfrl1a is sufficient to abolish cartilage derivatives of the ceratobranchials. Using an Fgfrl1a-deficient model, we analyzed expression of genes critical for chondrogenesis in the different compartments of the developing pharyngeal arch. Fgfrl1a-depleted animals demonstrate typical neural crest specification and migration to populate the arch primordia as well as normal pouch segmentation. However, in the absence of Fgfrl1a, larvae fail to express the transcription factor glial cells missing 2 (gcm2), a gene necessary for cartilage and gill filament formation, in the ectodermal lining of the branchial arches. In addition, two transcription factors essential for chondrogenesis, sox9a and runx2b, fail to express within the mesenchymal condensations of the branchial arches. A duplicate zebrafish gene, fgfrl1b, has now been identified. We show that Fgfrl1b is also required for proper formation of all ventral cartilage elements and acts cooperatively with Fgfrl1a during gill cartilage formation.
authors.affiliation: Department of Molecular Medicine & Pathology, School of Medical Sciences, The University of Auckland, P.O. 92019, Auckland, New Zealand.
authors.forename: Chris
authors.initials: C
authors.lastname: Hall
authors.forename: Maria Vega
authors.initials: MV
authors.lastname: Flores
authors.forename: Greg
authors.initials: G
authors.lastname: Murison
authors.forename: Kathy
authors.initials: K
authors.lastname: Crosier
authors.forename: Phil
authors.initials: P
authors.lastname: Crosier
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001934:Branchial Region / Q000737:chemistry / Q000196:embryology; D002356:Cartilage / Q000737:chemistry / Q000196:embryology*; D002465:Cell Movement / Q000235:genetics; D004268:DNA-Binding Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D004475:Ectoderm / Q000737:chemistry / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000378:metabolism; D047108:Embryonic Development / Q000235:genetics; D005880:Gills / Q000737:chemistry / Q000196:embryology*; D024002:HMGB Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009432:Neural Crest / Q000166:cytology; D010802:Phylogeny; D017468:Receptors, Fibroblast Growth Factor / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D055758:SOX9 Transcription Factor; D014157:Transcription Factors / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D015027:Zebrafish / Q000196:embryology* / Q000235:genetics; D029961:Zebrafish Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
chemical_list: D004268:DNA-Binding Proteins; C518798:Fgfrl1a protein, zebrafish; C518799:Fgfrl1b protein, zebrafish; D024002:HMGB Proteins; D017468:Receptors, Fibroblast Growth Factor; C502546:Runx2b protein, zebrafish; D055758:SOX9 Transcription Factor; C504918:Sox9a protein, zebrafish; D014157:Transcription Factors; D029961:Zebrafish Proteins; C501172:gcm2 protein, zebrafish