The role of BMP signaling in outgrowth and patterning of the Xenopus tail bud.
Tail bud formation in Xenopus depends on interaction between a dorsal domain (dorsal roof) expressing lunatic fringe and Notch, and a ventral domain (posterior wall) expressing the Notch ligand Delta. Ectopic expression of an activated form of Notch, Notch ICD, by means of an animal cap graft into the posterior neural plate, results in the formation of an ectopic tail-like structure containing a neural tube and fin. However, somites are never formed in these tails. Here, we show that BMP signaling is activated in the posterior wall of the tail bud and is involved in the formation of tail somites from this region. Grafts into the posterior neural plate, in which BMP signaling is activated, will form tail-like outgrowths. Unlike the Notch ICD tails, the BMP tails contain well-organized somites as well as neural tube and fin, with the graft contributing to both somites and neural tube. Through a variety of epistasis-type experiments, we show that the most likely model involves a requirement for BMP signaling upstream of Notch activation, resulting in formation of the secondary neural tube, as well as a Notch-independent pathway leading to the formation of tail somites from the posterior wall.
Beck
C W
CW
Developmental Biology Programme, Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath, BA2 7AY, United Kingdom. c.beck@bath.ac.uk
Whitman
M
M
Slack
J M
JM
D000818:Animals; D019485:Bone Morphogenetic Proteins / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism; D005799:Genes, Dominant; D017930:Genes, Reporter; D005819:Genetic Markers; D018398:Homeodomain Proteins / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins; D008024:Ligands; D008156:Luciferases / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism*; D008954:Models, Biological; D009432:Neural Crest / Q000196:embryology*; D010641:Phenotype; D010750:Phosphoproteins / Q000378:metabolism; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000378:metabolism; D051880:Receptors, Notch; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D051785:Smad Proteins; D051902:Smad5 Protein; D013623:Tail / Q000196:embryology*; D015534:Trans-Activators / Q000378:metabolism; D014981:Xenopus; D029867:Xenopus Proteins
D019485:Bone Morphogenetic Proteins; D004268:DNA-Binding Proteins; C094040:EVX1 protein, Xenopus; D005819:Genetic Markers; D018398:Homeodomain Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008024:Ligands; D008565:Membrane Proteins; D010750:Phosphoproteins; D012333:RNA, Messenger; D051880:Receptors, Notch; D051785:Smad Proteins; D051902:Smad5 Protein; C497800:Smad5 protein, Xenopus; D015534:Trans-Activators; D029867:Xenopus Proteins; C064045:delta protein; D008156:Luciferases