Abstract
Purpose: :
Many mutations which cause inherited retinal diseases such as retinitis pigmentosa (RP) have been identified. However, the mechanism of photoreceptor cell death in such diseases remains unknown. The purpose of our study was to generate transgenic zebrafish with one of the rhodopsin mutations at position 296 (K296E), which is associated with autosomal dominant retinitis pigmentosa (ADRP) in human, and to investigate the phenotype in such transgenic zebrafish.
Methods: :
We used the tol2 transposon system to produce transgenic zebrafish with the rhodopsin K296E mutation associated with ADRP in human for analysis. This K296E transgenic fish was then crossed with a fish whose photoreceptors can be visualized with the zebrafish rhodopsin promoter-driven green fluorescent protein (GFP). The number of surviving photoreceptors on the cryosections was counted 7 and 14 days after fertilization by means of fluorescent microscopy for both wild type and K296E transgenic fish. In addition, we compared the thickness of the outer nuclear layer (ONL) of K296E transgenic fish to that of wild type 10 months after fertilization.
Results: :
The number of surviving photoreceptor cells of wild type and K296E transgenic fish was not significantly different 7 days after fertilization (p=0.261). Fourteen days after fertilization, however, this number in the K296E retina was significantly reduced compared with that in wild type (p<0.000467), and 10 months after fertilization, the thickness of ONL of K296E fish was thinner (83%) than that of wild type fish.
Conclusions: :
The number of surviving photoreceptor cells in the K296E transgenic retina had started to decrease by 14 days after fertilization. This finding for the phenotype demonstrates that K296E transgenic zebrafish can be considered an animal model of retinitis pigmentosa.
Keywords: retinal degenerations: cell biology • photoreceptors • apoptosis/cell death