The ventralizing activity of Radar, a maternally expressed bone morphogenetic protein, reveals complex bone morphogenetic protein interactions controlling dorso-ventral patterning in zebrafish.
In Xenopus and zebrafish, BMP2, 4 and 7 have been implicated, after the onset of zygotic expression, in inducing and maintaining ventro-lateral cell fate during early development. We provide evidence here that a maternally expressed bone morphogenetic protein (BMP), Radar, may control early ventral specification in zebrafish. We show that Radar ventralizes zebrafish embryos and induces the early expression of bmp2b and bmp4. The analysis of Radar overexpression in both swirl/bmp2b mutants and embryos expressing truncated BMP receptors shows that Radar-induced ventralization is dependent on functional BMP2/4 pathways, and may initially rely on an Alk6-related signaling pathway. Finally, we show that while radar-injected swirl embryos still exhibit a strongly dorsalized phenotype, the overexpression of Radar into swirl/bmp2b mutant embryos restores ventral marker expression, including bmp4 expression. Our results suggest that a complex regulation of different BMP pathways controls dorso-ventral (DV) patterning from early cleavage stages until somitogenesis.
Goutel
C
C
INSERM U 368, Ecole Normale Supérieure, 46 rue d'Ulm, 75005, Paris, France.
Kishimoto
Y
Y
Schulte-Merker
S
S
Rosa
F
F
D000483:Alleles; D000818:Animals; D055396:Bone Morphogenetic Protein 2; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins / Q000096:biosynthesis* / Q000378:metabolism* / Q000502:physiology; D019070:Cell Lineage; D004625:Embryo, Nonmammalian / Q000378:metabolism; D005260:Female; D055431:Growth Differentiation Factor 6; D006720:Homozygote; D017403:In Situ Hybridization; D009035:Mothers; D009154:Mutation; D010641:Phenotype; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013997:Time Factors; D016212:Transforming Growth Factor beta; D015854:Up-Regulation; D029867:Xenopus Proteins; D015027:Zebrafish / Q000196:embryology* / Q000235:genetics; D029961:Zebrafish Proteins
D055396:Bone Morphogenetic Protein 2; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins; D055431:Growth Differentiation Factor 6; D016212:Transforming Growth Factor beta; D029867:Xenopus Proteins; D029961:Zebrafish Proteins; C525812:bmp4 protein, Xenopus; C525813:bmp4 protein, zebrafish; C420987:gdf6a protein, zebrafish