A systematic survey of expression and function of zebrafish frizzled genes

• Published in: PloS one Vol. 8; no. 1; p. e54833
• Main Authors: Nikaido, Masataka, Law, Edward W P, Kelsh, Robert N
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 22.01.2013; Public Library of Science (PLoS)
• Subjects: Animal genetics; Animals; Biochemistry; Biology; Body Patterning - genetics; Cell adhesion & migration; Convergence; Danio rerio; Embryo, Nonmammalian - metabolism; Embryos; Fertilization; Frizzled protein; Frizzled Receptors - genetics; Frizzled Receptors - metabolism; Gastrulation; Gastrulation - genetics; Gene expression; Gene Expression Regulation, Developmental; Gene families; Genes; Genetic aspects; Genomes; Genomics; Heparan sulfate; Kinases; Ligands; Melanocytes; Mesoderm; Mesoderm - cytology; Mesoderm - growth & development; Neural crest; Neural plate; Neural tube; Neural Tube - growth & development; Neural Tube - metabolism; Neurosciences; Proteins; Receptors; Receptors, Cell Surface - genetics; Receptors, Cell Surface - metabolism; Receptors, Neurotransmitter - genetics; Receptors, Neurotransmitter - metabolism; Signal Transduction; Signaling; Specifications; Surveys; Wnt protein; Wnt Signaling Pathway - genetics; Xenopus; Zebrafish; Zebrafish - genetics; Zebrafish - growth & development; Zebrafish Proteins - genetics; Zebrafish Proteins - metabolism
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0054833

Wnt signaling is crucial for the regulation of numerous processes in development. Consistent with this, the gene families for both the ligands (Wnts) and receptors (Frizzleds) are very large. Surprisingly, while we have a reasonable understanding of the Wnt ligands likely to mediate specific Wnt-dependent processes, the corresponding receptors usually remain to be elucidated. Taking advantage of the zebrafish model's excellent genomic and genetic properties, we undertook a comprehensive analysis of the expression patterns of frizzled (fzd) genes in zebrafish. To explore their functions, we focused on testing their requirement in several developmental events known to be regulated by Wnt signaling, convergent extension movements of gastrulation, neural crest induction, and melanocyte specification. We found fourteen distinct fzd genes in the zebrafish genome. Systematic analysis of their expression patterns between 1-somite and 30 hours post-fertilization revealed complex, dynamic and overlapping expression patterns. This analysis demonstrated that only fzd3a, fzd9b, and fzd10 are expressed in the dorsal neural tube at stages corresponding to the timing of melanocyte specification. Surprisingly, however, morpholino knockdown of these, alone or in combination, gave no indication of reduction of melanocytes, suggesting the important involvement of untested fzds or another type of Wnt receptor in this process. Likewise, we found only fzd7b and fzd10 expressed at the border of the neural plate at stages appropriate for neural crest induction. However, neural crest markers were not reduced by knockdown of these receptors. Instead, these morpholino knockdown studies showed that fzd7a and fzd7b work co-operatively to regulate convergent extension movement during gastrulation. Furthermore, we show that the two fzd7 genes function together with fzd10 to regulate epiboly movements and mesoderm differentiation.