Inhibition of floor plate differentiation by Pax3: evidence from ectopic expression in transgenic mice.
The Pax genes containing a complete paired-type homeobox are expressed in restricted dorsoventral domains of the undifferentiated neuroepithelium. Their expression respond to signals that pattern the neural tube and which emanate from the notochord, floor plate and overlying ectoderm. In order to determine whether the dorsally restricted Pax3 gene can influence the fate of cells within the neural tube, we produced transgenic mice overexpressing Pax3 in the entire neural tube under the Hoxb-4 promoter/region A enhancer. In two distinct transgenic mouse lines, we observed embryos with abnormal limb, eye, brain and neural tube development. Expression of Pax3 was not sufficient to dorsalize cells from the ventral intermediate zone, which still expressed ventral markers. However, in these embryos, expression of Pax3 at the ventral midline was associated with the absence of floor plate differentiation. Under these conditions, motor neurons still differentiated in the ventral spinal cord, although in fewer numbers.
Tremblay
P
P
Department of Molecular Cell Biology, Max Planck Institute of Biophysical Chemistry, Gottingen, Germany.
Pituello
F
F
Gruss
P
P
D000818:Animals; D001483:Base Sequence; D015415:Biomarkers; D002454:Cell Differentiation; D002490:Central Nervous System / Q000196:embryology*; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D005260:Female; D018507:Gene Expression Regulation, Developmental; D008297:Male; D008636:Mesencephalon / Q000196:embryology / Q000378:metabolism; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D000072041:PAX3 Transcription Factor; D051761:Paired Box Transcription Factors; D013116:Spinal Cord / Q000196:embryology; D014157:Transcription Factors
D015415:Biomarkers; D017931:DNA Primers; D004268:DNA-Binding Proteins; D000072041:PAX3 Transcription Factor; D051761:Paired Box Transcription Factors; D014157:Transcription Factors; C068686:Pax3 protein, mouse