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- Title
Nuclear -catenin promotes non-neural ectoderm and posterior cell fates in amphioxus embryos.
- Authors
Linda Z. Holland; Kristen A. Panfilio; Roger Chastain; Michael Schubert; Nicholas D. Holland
- Abstract
In vertebrate development, Wnt/-catenin signaling has an early role in specification of dorsal/anterior identity and a late one in posterior specification. To understand the evolution of these roles, we cloned -catenin from the invertebrate chordate amphioxus. The exon/intron organization of -catenin is highly conserved between amphioxus and other animals including a cnidarian, but not Drosophila. In development, amphioxus -catenin is concentrated in all nuclei from the 16-cell stage until the onset of gastrulation when it becomes undetectable in presumptive mesendoderm. Li+, which up-regulates Wnt/-catenin signaling, had no detectable effect on axial patterning when applied before the late blastula stage, suggesting that a role for -catenin in specification of dorsal/anterior identity may be a vertebrate innovation. From the mid-gastrula through the neurula stage, the highest levels of nuclear -catenin are around the blastopore. In the early neurula, -catenin is down-regulated in the neural plate, but remains high in adjacent non-neural ectoderm. Embryos treated with Li+ at the late blastula stage are markedly posteriorized and lack a neural plate. These results suggest that in amphioxus, as in vertebrates, down-regulation of Wnt/-catenin signaling in the neural plate is necessary for maintenance of the neuroectoderm and that a major evolutionarily conserved role of Wnt/-catenin signaling is to specify posterior identity and pattern the anterior/posterior axis. Developmental Dynamics 233:14301443, 2005. 2005 Wiley-Liss, Inc.
- Subjects
VERTEBRATES; EMBRYOLOGY; DEVELOPMENTAL biology; ANIMAL morphology
- Publication
Developmental Dynamics, 2005, Vol 233, Issue 4, p1430
- ISSN
1058-8388
- Publication type
Article
- DOI
10.1002/dvdy.20473