PUBLICATION

Direct binding of Lef1 to sites in the boz promoter may mediate pre-midblastula-transition activation of boz expression

Authors
Leung, T., Söll, I., Arnold, S.J., Kemler, R., and Driever, W.
ID
ZDB-PUB-031103-6
Date
2003
Source
Developmental Dynamics : an official publication of the American Association of Anatomists   228(3): 424-432 (Journal)
Registered Authors
Driever, Wolfgang, Leung, Tin Chung, Söll, Iris
Keywords
zebrafish, beta-catenin, bozozok, gastrula organizer, dorsoventral pattern, Tcf1/Lef-1, Nieuwkoop center, midblastula transition
MeSH Terms
  • Animals
  • Base Sequence
  • Binding Sites
  • Blastula/cytology
  • Blastula/physiology*
  • DNA-Binding Proteins/metabolism*
  • Gene Expression Regulation, Developmental/genetics*
  • Lymphoid Enhancer-Binding Factor 1
  • Molecular Sequence Data
  • Promoter Regions, Genetic/genetics*
  • Protein Binding
  • Transcription Factors/metabolism*
  • Transcriptional Activation
  • Zebrafish/genetics*
  • Zebrafish Proteins/metabolism
PubMed
14579381 Full text @ Dev. Dyn.
Abstract
The Nieuwkoop center provides signals essential for the establishment of the dorsal gastrula organizer in vertebrates. Activation of beta-catenin is one of the events in the Nieuwkoop center that lead to activation of dorsal-specific genes during blastula and early gastrula stages. Zebrafish bozozok (boz) mutant embryos have severe defects in axial mesoderm and anterior neuroectoderm. The boz gene is activated in the organizer in response to beta-catenin signaling, and Boz protein has been demonstrated to contribute to organizer formation by repression of ventralizing genes, including bmp2b, vega1, and vega2. Here, we investigate the timing and molecular mechanism by which boz expression is activated in the organizer. We demonstrate that boz is already expressed before midblastula transition (MBT). We further identify high-affinity binding sites for Tcf/Lef1 within the boz promoter region. These sites, together with the finding that beta-catenin induces boz expression, indicate that transcription of boz may be activated directly by beta-catenin/Lef1. We hypothesize that pre-MBT activation of boz may be important to build up a sufficiently strong antagonizing activity against zygotic ventralizing genes activated immediately post-MBT. Thus, the early onset of boz expression may be crucial for organizer establishment in the presence of ubiquitous maternal activators of ventralizing genes.
Genes / Markers
Figures
Expression
Phenotype
Mutations / Transgenics
Human Disease / Model
Sequence Targeting Reagents
Fish
Antibodies
Orthology
Engineered Foreign Genes
Mapping