Wnt signalling mediated by Tbx2b regulates cell migration during formation of the neural plate.
During gastrulation, optimal adhesion and receptivity to signalling cues are essential for cells to acquire new positions and identities via coordinated cell movements. T-box transcription factors and the Wnt signalling pathways are known to play important roles in these processes. Zebrafish tbx2b, a member of the TBX2 family, has previously been shown to be required for the specification of midline mesoderm. We show here that tbx2b transcripts are present during mid-gastrula before its expression is detected by whole-mount in situ hybridization. Isolated ectodermal cells deficient in Tbx2b have altered cell surface properties and the level of cadherins in these cells is lower. In chimaeric embryos generated by cell transplantation and single blastomere injections, Tbx2b-deficient cells are defective in cell movement in a cell-autonomous manner, resulting in their exclusion from the developing neural plate. Using this ;exclusion' phenotype as a screen, we show that Tbx2b acts within the context of Fz7 signalling. The exclusion of cells lacking T-box proteins in chimeras during development was demonstrated with other T-box genes and may indicate a general functional mechanism for T-box proteins.
Fong
Steven H
SH
Institute of Molecular and Cell Biology, 61 Biopolis Drive, Proteos, 138673 Singapore.
Emelyanov
Alexander
A
Teh
Cathleen
C
Korzh
Vladimir
V
D000818:Animals; D002465:Cell Movement / Q000502:physiology*; D002678:Chimera / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D017403:In Situ Hybridization; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism*; D009024:Morphogenesis; D016376:Oligonucleotides, Antisense / Q000235:genetics / Q000378:metabolism; D010641:Phenotype; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D020825:T-Box Domain Proteins; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D051153:Wnt Proteins; D015027:Zebrafish / Q000033:anatomy & histology / Q000196:embryology*; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism*
D004268:DNA-Binding Proteins; D036341:Intercellular Signaling Peptides and Proteins; D016376:Oligonucleotides, Antisense; D011956:Receptors, Cell Surface; D020825:T-Box Domain Proteins; D014157:Transcription Factors; D051153:Wnt Proteins; D029961:Zebrafish Proteins; C470289:fzd7a protein, zebrafish; C120107:tbx2b protein, zebrafish