Involvement of frizzled-10 in Wnt-7a signaling during chick limb development.
The dorsal ectoderm of the limb bud is known to regulate anterior-posterior patterning as well as dorsal-ventral patterning during vertebrate limb morphogenesis. Wnt-7a, expressed in the dorsal ectoderm, encodes a key molecule implicated in these events. In the present study, chicken frizzled-10 (Fz-10) encoding a Wnt receptor was used to study mechanisms of Wnt-7a signaling during chick limb patterning, because its expression is restricted to the posterior-distal region of the dorsal limb bud. Fz-10 transcripts colocalize with Sonic hedgehog (Shh) in the dorsal side of stages 18-23 chick limb buds. It was demonstrated that Fz-10 interacts with Wnt-7a to induce synergistically the expression of Wnt-responsive genes, such as Siamois and Xnr3, in Xenopus animal cap assays. In the chick limb bud, Fz-10 expression is regulated by Shh and a signal from the dorsal ectoderm, presumably Wnt-7a, but not by signals from the apical ectodermal ridge. These results suggest that Fz-10 acts as a receptor for Wnt-7a and has a positive effect on Shh expression in the chick limb bud.
Kawakami
Y
Y
Department of Molecular Biology, Kawasaki Medical School, Kurashiki, Japan.
Wada
N
N
Nishimatsu
S
S
Nohno
T
T
D000818:Animals; D030161:Avian Proteins; D019521:Body Patterning; D002642:Chick Embryo; D003001:Cloning, Molecular; D005121:Extremities / Q000196:embryology*; D051157:Frizzled Receptors; D053823:Hedgehog Proteins; D009024:Morphogenesis; D011506:Proteins / Q000235:genetics; D011518:Proto-Oncogene Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D011956:Receptors, Cell Surface / Q000502:physiology*; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000502:physiology*; D015534:Trans-Activators; D051153:Wnt Proteins; D014981:Xenopus / Q000196:embryology
D030161:Avian Proteins; C492383:FZD10 protein, Gallus gallus; D051157:Frizzled Receptors; D053823:Hedgehog Proteins; D011506:Proteins; D011518:Proto-Oncogene Proteins; D011956:Receptors, Cell Surface; D015534:Trans-Activators; C490509:WNT7A protein, Gallus gallus; D051153:Wnt Proteins