title: Eda/Edar signaling guides fin ray formation with preceding osteoblast differentiation, as revealed by analyses of the medaka all-fin less mutant afl.
abstract: BACKGROUND
  Ectodysplasin (Eda) signaling is essential for the morphogenesis of several ectodermal appendages.
  
  
  RESULTS
  Here, we report a medaka mutant, all-fin less (afl), which has a nonsense mutation in its eda gene. The adult afl fish displayed various abnormalities of its dermal skeleton, such as short and twisted fin rays, missing and abnormally shaped scales and teeth, and skull deformation. Focusing on the developing fin rays in the caudal region of afl larvae, we found that the fin rays did not elongate; although the initial formation of fin rays proceeded normally. Additionally, eda expression was lost, and the expression pattern of edar, the gene for the receptor of Eda, was different from wild-type one. In vivo imaging of the double-transgenic medaka expressing enhanced green fluorescent protein under control of the edar promoter and DsRed under control of the osterix promoter revealed that edar expression preceded that of osterix and that the edar-expressing cells migrated in the direction of fin ray elongation, indicating that the Eda/Edar signaling event precedes osteoblast differentiation.
  
  
  CONCLUSIONS
  Our findings provide evidence that Eda signaling accompanied with the binding of Eda to Edar are essential for fin ray formation guided by cell migration.
authors.affiliation: Department of Biological Information, Tokyo Institute of Technology, Yokohama, Japan.
authors.forename: Yuuki
authors.initials: Y
authors.lastname: Iida
authors.forename: Kenta
authors.initials: K
authors.lastname: Hibiya
authors.forename: Keiji
authors.initials: K
authors.lastname: Inohaya
authors.forename: Akira
authors.initials: A
authors.lastname: Kudo
mesh_terms: D058500:Animal Fins / Q000166:cytology / Q000196:embryology*; D000818:Animals; D002454:Cell Differentiation / Q000502:physiology*; D053331:Ectodysplasins / Q000235:genetics / Q000378:metabolism*; D053339:Edar Receptor / Q000235:genetics / Q000378:metabolism*; D029941:Fish Proteins / Q000235:genetics / Q000378:metabolism*; D009990:Oryzias / Q000196:embryology* / Q000235:genetics; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D053331:Ectodysplasins; D053339:Edar Receptor; D029941:Fish Proteins
keywords: ectodysplasin; edar; fin ray; medaka mutant; osteoblast; osterix