Characterization of avian frizzled genes in cranial placode development.
To determine the possible role of Wnt signaling in cranial placode development, we have cloned several chick frizzled genes, a family of putative Wnt receptor molecules, and analyzed their expression during chick embryogenesis. Chick frizzled-2 (cFz-2) and frizzled-7 (cFz-7) are expressed broadly in cranial ectoderm, tissue that is competent to express markers of the trigeminal placode (Stark et al., 1997. Development 124, 4287-4295; Baker et al., 1999. Development 126, 147-156). In addition, cFz-2 and cFz-7 are uniquely expressed in other cranial placodes, including the olfactory, lens, and otic placodes. Chick frizzled-1 (cFz-1) is expressed in the lens, otic placode and, along with cFz-7, in epibranchial placodes. Each frizzled gene expressed in the otic placode displays a unique domain of expression: cFz-1 transcripts are detected in the medial wall of the vesicle, cFz-2 in the rostral rim of the vesicle, and cFz-7 in the lateral half of the vesicle. Other chick frizzled family members cloned that do not show striking expression in cranial placodes include frizzled-4 (cFz-4), frizzled-8 (cFz-8), frizzled-9 (cFz-9), and frizzled-10 (cFz-10). A brief summary of their expression is given, along with a brief summary of non-placodal expression of cFz-1, cFz-2, and cFz-7. In all, frizzled genes show dynamic expression at key times during embryonic development, particularly in the cranial placodes.
Stark
M R
MR
Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City 84132, USA. michael.stark@hsc.utah.edu
Biggs
J J
JJ
Schoenwolf
G C
GC
Rao
M S
MS
D000818:Animals; D001483:Base Sequence; D002642:Chick Embryo; D018076:DNA, Complementary; D051157:Frizzled Receptors; D008969:Molecular Sequence Data; D011956:Receptors, Cell Surface / Q000235:genetics*; D043562:Receptors, G-Protein-Coupled; D017981:Receptors, Neurotransmitter / Q000235:genetics*; D012886:Skull / Q000196:embryology*
D018076:DNA, Complementary; C489740:FZD1 protein, human; C489742:FZD2 protein, human; D051157:Frizzled Receptors; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; D017981:Receptors, Neurotransmitter