ZFIN ID: ZDB-PUB-060210-6
The homeobox gene irx1a is required for the propagation of the neurogenic waves in the zebrafish retina
Cheng, C.W., Yan, C.H., Hui, C.C., Strähle, U., and Cheng, S.H.
Date: 2006
Source: Mechanisms of Development   123(3): 252-263 (Journal)
Registered Authors: Cheng, Shuk Han, Strähle, Uwe
Keywords: Zebrafish, Retinogenesis, Wave propagation, Iroquois, Sonic hedgehog
MeSH Terms:
  • Animals
  • Animals, Genetically Modified
  • Cell Differentiation
  • Eye/embryology*
  • Eye Diseases/genetics
  • Eye Diseases/metabolism
  • Fibroblast Growth Factors/metabolism
  • Gene Expression Regulation, Developmental
  • Hedgehog Proteins/genetics
  • Hedgehog Proteins/metabolism
  • Homeodomain Proteins/genetics*
  • Homeodomain Proteins/metabolism
  • Retina/cytology
  • Retina/embryology*
  • Retina/metabolism
  • Retinal Ganglion Cells/metabolism*
  • Signal Transduction
  • Transcription Factors/genetics*
  • Transcription Factors/metabolism
  • Zebrafish
  • Zebrafish Proteins/genetics*
  • Zebrafish Proteins/metabolism
PubMed: 16457994 Full text @ Mech. Dev.
Neurogenesis in the compound eyes of Drosophila and the camera eyes of vertebrates spreads in a wave-like fashion. In both phyla, waves of hedgehog expression are known to drive the wave of neuronal differentiation. The mechanism controlling the propagation of hedgehog expression during retinogenesis of the vertebrate eye is poorly understood. The Iroquois homeobox genes play important roles in Drosophila eye development; they are required for the up-regulation of hedgehog expression during propagation of the morphogenetic furrow. Here, we show that the zebrafish Iroquois homolog irx1a is expressed during retinogenesis and knockdown of irx1a results in a retinal phenotype strikingly similar to those of sonic hedgehog (shh) mutants. Analysis of shh-GFP transgene expression in irx1a knockdown retinas revealed that irx1a is required for the propagation of shh expression through the retina. Transplantation experiments illustrated that the effects of irx1a on shh expression are both cell-autonomous and non-cell-autonomous. Our results reveal a role for Iroquois genes in controlling hedgehog expression during vertebrate retinogenesis.