ZFIN ID: ZDB-PUB-080616-25
Notch resolves mixed neural identities in the zebrafish epiphysis
Cau, E., Quillien, A., and Blader, P.
Date: 2008
Source: Development (Cambridge, England)   135(14): 2391-2401 (Journal)
Registered Authors: Blader, Patrick
Keywords: Notch, Neural specification, Zebrafish, Epiphysis, Photoreceptor, Projection neuron
MeSH Terms:
  • Animals
  • Animals, Genetically Modified
  • Embryo, Nonmammalian
  • Epiphyses/innervation*
  • Epiphyses/metabolism
  • Fluorescent Antibody Technique, Indirect
  • Green Fluorescent Proteins/metabolism
  • Homozygote
  • In Situ Hybridization
  • Models, Neurological
  • Nerve Tissue Proteins/genetics*
  • Nerve Tissue Proteins/physiology*
  • Neurons/physiology*
  • Photoreceptor Cells/physiology*
  • Receptors, Notch/genetics
  • Receptors, Notch/physiology*
  • Signal Transduction
  • Transgenes
  • Zebrafish/embryology
  • Zebrafish/genetics*
PubMed: 18550717 Full text @ Development
Manipulation of Notch activity alters neuronal subtype identity in vertebrate neuronal lineages. Nonetheless, it remains controversial whether Notch activity diversifies cell fate by regulating the timing of neurogenesis or acts directly in neuronal subtype specification. Here, we address the role of Notch in the zebrafish epiphysis, a simple structure containing only two neural subtypes: projection neurons and photoreceptors. Reducing the activity of the Notch pathway results in an excess of projection neurons at the expense of photoreceptors, as well as an increase in cells retaining a mixed identity. However, although forced activation of the pathway inhibits the projection neuron fate, it does not promote photoreceptor identity. As birthdating experiments show that projection neurons and photoreceptors are born simultaneously, Notch acts directly during neuronal specification rather than by controlling the timing of neurogenesis. Finally, our data suggest that two distinct signals are required for photoreceptor fate specification: one for the induction of the photoreceptor fate and the other, involving Notch, for the inhibition of projection neuron traits. We propose a novel model in which Notch resolves mixed neural identities by repressing an undesired genetic program.