Delayed expression of the Crx gene and photoreceptor development in the Chx10-deficient retina.
OBJECTIVE
The Chx10 homeobox gene is expressed in neural progenitor cells during retinal development. The absence of Chx10 causes microphthalmia in humans and in the mouse mutant ocular retardation. The purpose of this study was to examine how neuronal development is affected by absence of the Chx10 transcription factor in the mouse retina.


METHODS
Expression of transcription factor genes, Crx, Pou4f2, and Pax6, that mark specific cell types as they begin to differentiate was analyzed by RNA in situ hybridization of retina from wild-type and Chx10-null ocular retardation mice (Chx10(or-J/or-J)). RT-PCR analysis was used to compare expression of these genes and putative targets of Crx regulation. Photoreceptor development was analyzed by using peanut agglutinin (PNA)-rhodamine and blue cone opsin antibody to label cones and rhodopsin antibody to label rods.


RESULTS
The photoreceptor gene Crx, normally expressed during embryonic retinal development, was not detected in the embryonic mutant retina, but was expressed after birth. Expression of the targets of Crx regulation, rhodopsin, peripherin, rod phosphodiesterase beta (Pdeb), and arrestin, with the exception of interphotoreceptor retinoid binding protein (Irbp), was delayed in the Chx10(or-J/or-J) retina. Rhodopsin localization in rod outer segments was also delayed. By contrast, temporal and spatial expression of Pou4f2 and Pax6 in developing ganglion and amacrine cells and PNA and blue opsin in developing cone cells was relatively normal in the mutant.


CONCLUSIONS
Delay of the normal temporal expression of genes essential for photoreceptor disc morphogenesis leads to failure of correct rod and cone outer segment formation in the Chx10(or-J/or-J) mutant retina. In addition, the absence of Chx10 appears to affect the development of late-born cells more than that of early-born cells, in that a low number of rods develops, whereas formation of ganglion, amacrine, and cone cells is relatively unaffected.
Rutherford
Adam D
AD
Developmental Biology Unit, Institute of Child Health, University College London, London, United Kingdom.
Dhomen
Nathalie
N
Smith
Hazel K
HK
Sowden
Jane C
JC
D015106:3',5'-Cyclic-GMP Phosphodiesterases / Q000378:metabolism; D000818:Animals; D019393:Arrestin / Q000378:metabolism; D054707:Cyclic Nucleotide Phosphodiesterases, Type 6; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D005136:Eye Proteins; D019084:Fluorescent Antibody Technique, Indirect; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D017403:In Situ Hybridization; D007381:Intermediate Filament Proteins / Q000378:metabolism; D008562:Membrane Glycoproteins; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D009419:Nerve Tissue Proteins / Q000378:metabolism; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; D064531:Peripherins; D020419:Photoreceptor Cells, Vertebrate / Q000378:metabolism* / Q000473:pathology; D012333:RNA, Messenger / Q000378:metabolism; D012097:Repressor Proteins; D012160:Retina / Q000196:embryology* / Q000473:pathology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012243:Rhodopsin / Q000378:metabolism; D017299:Rod Opsins / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism; D050818:Transcription Factor Brn-3; D050820:Transcription Factor Brn-3B; D014157:Transcription Factors / Q000172:deficiency / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
D019393:Arrestin; D004268:DNA-Binding Proteins; D005136:Eye Proteins; D018398:Homeodomain Proteins; D007381:Intermediate Filament Proteins; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; D000071841:PAX6 Transcription Factor; C000605730:PAX6 protein, human; C578994:PRPH protein, human; D051761:Paired Box Transcription Factors; C000605732:Pax6 protein, mouse; D064531:Peripherins; D012333:RNA, Messenger; D012097:Repressor Proteins; D017299:Rod Opsins; D015534:Trans-Activators; D050818:Transcription Factor Brn-3; D050820:Transcription Factor Brn-3B; D014157:Transcription Factors; C088975:Vsx2 protein, mouse; C109288:cone rod homeobox protein; D012243:Rhodopsin; D015106:3',5'-Cyclic-GMP Phosphodiesterases; D054707:Cyclic Nucleotide Phosphodiesterases, Type 6; C517438:Pde6b protein, mouse