The requirement of pax6 for postnatal eye development: evidence from experimental mouse chimeras.
OBJECTIVE
The small eye mouse mutant (Sey) is caused by a mutation of the Pax6 gene. Previous studies, in which aggregation chimeras were used, have demonstrated that Sey/Sey cells contribute poorly to the neural retina forming small clumps of cells restricted to the inner retina at embryonic day 16.5. In addition, Sey/+ cells are absent from the lens epithelium during this embryonic period and postnatally. This study was conducted to determine the fates of these Sey/Sey and Sey/+ cells with continued development in chimeric mouse eyes.


METHODS
Observations were made on heterozygous and homozygous Sey cells in chimeric eyes from postnatal day (P)0 to P10.


RESULTS
In Sey/Sey<-->wild-type (wt) chimeras, all Sey/Sey cells originating from retinal progenitor cells died at perinatal times. The only remaining Sey/Sey cells in the neural retina were associated with blood vessels, including vascular endothelial cells, pericytes, astrocytes, and microglia, which have extraretinal origins. In contrast, Sey/+ cells formed all retinal cell classes. As previously reported, Sey/Sey cells were absent from the lens and corneal epithelium. However, in contrast to previous reports, Sey/+ cells contributed to the lens epithelium as well as corneal tissues, and Sey/Sey cells were absent from the anterior retinal pigment epithelium.


CONCLUSIONS
All evidence showed that, when Pax6 is absent at the initial stages of the development, Sey/Sey cells that contribute to the neural retina die, even when wild-type cells are available to provide normal environmental cues.
Li
Shengxiu
S
Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA.
Goldowitz
Dan
D
Swanson
Douglas J
DJ
D000818:Animals; D002678:Chimera / Q000235:genetics* / Q000378:metabolism; D019573:Epithelium, Corneal / Q000196:embryology / Q000378:metabolism; D005123:Eye / Q000196:embryology* / Q000378:metabolism; D005136:Eye Proteins / Q000502:physiology*; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D005838:Genotype; D018398:Homeodomain Proteins / Q000502:physiology*; D007124:Immunoenzyme Techniques; D007498:Iris / Q000196:embryology / Q000378:metabolism; D007908:Lens, Crystalline / Q000196:embryology / Q000378:metabolism; D051379:Mice; D008813:Mice, Inbred ICR; D008850:Microphthalmos / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors / Q000502:physiology*; D010641:Phenotype; D010857:Pigment Epithelium of Eye / Q000378:metabolism; D016133:Polymerase Chain Reaction; D012097:Repressor Proteins / Q000502:physiology*; D012160:Retina / Q000196:embryology / Q000378:metabolism
D005136:Eye Proteins; D018398:Homeodomain Proteins; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; C000605732:Pax6 protein, mouse; D012097:Repressor Proteins