Goldfish β-catenin cell-autonomously inhibits the expression of early neural development regulating gene vsx1

Abstract

β-catenin gene is essential for the formation of normal dorsal axial structure in vertebrates. Recent studies have provided evidence that β-catenin has a certain role in restricting the amount of organizer-induced neurectoderm formation in zebrafish and Xenopus laevis. To further understand how β-catenin represses the induction of neurectoderm formation and whether the inhibition of neural progenitor fates is essential for the normal organizer formation, it was investigated whether β-catenin was involved in repressing the early neural regulatory gene Visual system homeobox-1 (vsx1) expression during embryogenesis. It was observed that functional inhibition of endogenous β-catenin by morpholino oligonucleotides (MO) resulted in extensive and ubiquitous vsx1 expression, β-catenin could repress vsx1 promoter-driven GFP expression and transcriptional factor gene boz, the direct target gene of β-catenin, could directly repress vsx1 transcription by binding to vsx1 proximal promoter. These observations indicate that β-catenin can repress vsx1 ectopic expression cell-autonomously while it activates chordamesodermal genes expression in the precursory cells of chordamesoderm, suggesting both activation of chordamesodermal genes and repression of neural regulatory genes vsx1 in precursory chordamesoderm by β-catenin are essential for normal notochord formation.