Nuffield Laboratory of Ophthalmology and Oxford Eye Hospital Biomedical Research Centre, University of Oxford, John Radcliffe Hospital, United Kingdom.
Invest Ophthalmol Vis Sci. 2011 Aug 22;52(9):6617-23. doi: 10.1167/iovs.11-7932.
PURPOSE. To characterize anatomically and functionally the retinal degeneration observed in a transgenic mouse line (OPN1LW-EGFP) expressing enhanced green fluorescent protein (EGFP) in a subpopulation of cone photoreceptors, and to map the location of the transgenic insertion. METHODS. An anatomic comparison of cone survival was carried out between wild type (WT) and transgenic mice at three postnatal time points (P80, P140, and P245). Retinal function was assessed at P245 by ERG and included an ultraviolet flicker stimulus to isolate S-cone function. Chromosomal mapping by FISH and high-resolution mapping on DNA fibers (Fiber-FISH) were performed to identify the location of the transgenic insertion. RESULTS. GFP expression was largely absent in S-cones. Cone numbers were significantly reduced in OPN1LW-EGFP mice at all time points compared to WT, with cone loss independent of GFP expression. Anatomic loss correlated with a functional deficit in dark- and light-adapted ERG responses, including a reduction in UV-flicker response, confirming the degeneration of S-cones. The phenotype of heterozygote mice was slightly less severe than in homozygotes, consistent with a dominantly inherited cone dystrophy. The transgenic insertion mapped to a specific region on chromosome 10 orthologous with loci for progressive bifocal chorioretinal atrophy and North Carolina macular dystrophy on human chromosome 6. CONCLUSIONS. Cone loss is global in OPN1LW-EGFP mice and is independent of GFP expression. The mechanism underlying the degeneration remains elusive; however, disruption of loci associated with dominantly inherited retinal degenerations in humans makes this mouse of great interest.
目的。对在一个表达增强型绿色荧光蛋白（EGFP）的转基因鼠系（OPN1LW-EGFP）中观察到的视网膜变性进行解剖学和功能特征分析，并对转基因插入的位置进行定位。
方法。在三个出生后时间点（P80、P140 和 P245），对野生型（WT）和转基因小鼠的锥体存活进行解剖学比较。在 P245 时通过 ERG 评估视网膜功能，包括使用紫外线闪烁刺激来分离 S-锥体功能。通过荧光原位杂交（FISH）和 DNA 纤维上的高分辨率作图（纤维-FISH）进行染色体作图，以确定转基因插入的位置。
结果。GFP 表达在 S-锥体中基本不存在。与 WT 相比，在所有时间点，OPN1LW-EGFP 小鼠中的 GFP 表达均显著降低，且锥体丢失与 GFP 表达无关。解剖学上的损失与暗适应和明适应 ERG 反应的功能缺陷相关，包括 UV 闪烁反应的减少，这证实了 S-锥体的变性。杂合子小鼠的表型略轻于纯合子，与显性遗传的锥体营养不良一致。转基因插入位于与人类 6 号染色体上进行性双焦点脉络膜视网膜萎缩和北卡罗来纳州黄斑营养不良相关的特定区域。
结论。OPN1LW-EGFP 小鼠的锥体丢失是全身性的，与 GFP 表达无关。变性的机制尚不清楚；然而，破坏与人类显性遗传视网膜变性相关的基因座，使得这种老鼠具有极大的研究兴趣。
