Dissecting Wnt/beta-catenin signaling during gastrulation using RNA interference in mouse embryos.
Differential gene regulation integrated in time and space drives developmental programs during embryogenesis. To understand how the program of gastrulation is regulated by Wnt/beta-catenin signaling, we have used genome-wide expression profiling of conditional beta-catenin mutant embryos. Known Wnt/beta-catenin target genes, known components of other signaling pathways, as well as a number of uncharacterized genes were downregulated in these mutants. To further narrow down the set of differentially expressed genes, we used whole-mount in situ screening to associate gene expression with putative domains of Wnt activity. Several potential novel target genes were identified by this means and two, Grsf1 and Fragilis2, were functionally analyzed by RNA interference (RNAi) in completely embryonic stem (ES) cell-derived embryos. We show that the gene encoding the RNA-binding factor Grsf1 is important for axial elongation, mid/hindbrain development and axial mesoderm specification, and that Fragilis2, encoding a transmembrane protein, regulates epithelialization of the somites and paraxial mesoderm formation. Intriguingly, the knock-down phenotypes recapitulate several aspects of Wnt pathway mutants, suggesting that these genes are components of the downstream Wnt response. This functional genomic approach allows the rapid identification of functionally important components of embryonic development from large datasets of putative targets.
Lickert
Heiko
H
Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto M5G 1X5, Canada.
Cox
Brian
B
Wehrle
Christian
C
Taketo
Makoto M
MM
Kemler
Rolf
R
Rossant
Janet
J
D000469:Alkaline Phosphatase; D000818:Animals; D015152:Blotting, Northern; D019521:Body Patterning / Q000502:physiology*; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D005775:Gastrula / Q000502:physiology*; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D017403:In Situ Hybridization; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice / Q000196:embryology*; D008822:Mice, Transgenic; D020411:Oligonucleotide Array Sequence Analysis; D039102:Poly(A)-Binding Proteins / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D015534:Trans-Activators / Q000378:metabolism*; D051153:Wnt Proteins; D051176:beta Catenin
C495267:CTNNB1 protein, mouse; D003598:Cytoskeletal Proteins; C088356:GRSF1 protein, human; D036341:Intercellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D039102:Poly(A)-Binding Proteins; D034741:RNA, Small Interfering; D015534:Trans-Activators; D051153:Wnt Proteins; D051176:beta Catenin; C479378:fragilis2 protein, mouse; D000469:Alkaline Phosphatase