X-ngnr-1 and Xath3 promote ectopic expression of sensory neuron markers in the neurula ectoderm and have distinct inducing properties in the retina.
Xath3 encodes a Xenopus neuronal-specific basic helix-loop-helix transcription factor related to the Drosophila proneural factor atonal. We show here that Xath3 acts downstream of X-ngnr-1 during neuronal differentiation in the neural plate and retina and that its expression and activity are modulated by Notch signaling. X-ngnr-1 activates Xath3 and NeuroD by different mechanisms, and the latter two genes crossactivate each other. In the ectoderm, X-ngnr-1 and Xath3 have similar activities, inducing ectopic sensory neurons. Among the sensory-specific markers tested, only those that label cranial neurons were found to be ectopically activated. By contrast, in the retina, X-ngnr-1 and Xath3 overexpression promote the development of overlapping but distinct subtypes of retinal neurons. Together, these data suggest that X-ngnr-1 and Xath3 regulate successive stages of early neuronal differentiation and that, in addition to their general proneural properties, they may contribute, in a context-dependent manner, to some aspect of neuronal identity.
Perron
M
M
Department of Anatomy, University of Cambridge, Cambridge CB2 3DY, United Kingdom.
Opdecamp
K
K
Butler
K
K
Harris
W A
WA
Bellefroid
E J
EJ
D000818:Animals; D000943:Antigens, Differentiation; D051792:Basic Helix-Loop-Helix Proteins; D019521:Body Patterning; D002454:Cell Differentiation; D004475:Ectoderm; D004627:Embryonic Induction; D018257:Helix-Loop-Helix Motifs; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009420:Nervous System / Q000196:embryology*; D009475:Neurons, Afferent / Q000166:cytology*; D012160:Retina / Q000166:cytology / Q000196:embryology*; D014981:Xenopus / Q000196:embryology*; D029867:Xenopus Proteins
D000943:Antigens, Differentiation; D051792:Basic Helix-Loop-Helix Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D029867:Xenopus Proteins; C491279:NEUROD4 protein, Xenopus; C064045:delta protein; C101907:neurogenin, Xenopus