Abstract
The prevailing model for anteroposterior (AP) axis formation during vertebrate embryo genesis implies distinct organizer regions inducing head and trunk structures, respectively. A gradient of posteriorizing activity (transformer) which regulates AP patterning of the neuraxis has been suggested on the other hand by classical studies using amphibian embryos. Here, we will review the roles of Wnt signaling during head formation in various vertebrate model organisms. Early in vertebrate embryogenesis, organizer (and thus head) formation depends on a Wnt-type b-catenin-mediated signal. During gastrulation, posteriorizing Wnt/b-catenin signaling antagonizes the head organizer whose distinguishing feature is the secretion of Wnt inhibitors. The interplay between head organizer-derived Wnt inhibitors and posteriorizing Wnts establishes a gradient of Wnt/b-catenin activity that regulates AP patterning of the vertebrate gastrula. Thus, the concepts of head and trunk organizer and of the transformer gradient are reconciled in a dualistic view of AP axis formation.
| Original language | English |
|---|---|
| Title of host publication | Wnt Signalling in Development |
| Editors | M Kühl |
| Place of Publication | Georgetown, New York |
| Publisher | Landes Bioscience, Kluwer Academic/Plenum Publishers |
| Pages | 71 - 89 |
| Number of pages | 19 |
| Publication status | Published - 2003 |