A Naturally Occurring Mouse Model of Achromatopsia: Characterization of the Mutation in Cone Transducin and Subsequent Retinal Phenotype
A Naturally Occurring Mouse Model of Achromatopsia: Characterization of the Mutation in Cone Transducin and Subsequent Retinal Phenotype
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DOI：
10.1167/iovs.13-11831
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发表时间：
2013-05-01
影响因子：
4.4
通讯作者：
Fletcher, Erica L.
中科院分区：
文献类型：
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作者：
Jobling, Andrew I.;Vessey, Kirstan A.;Fletcher, Erica L.
目的.这项工作研究了一种新的，自然发生的色盲小鼠模型。鉴定了Gnat 2基因内的特定错义突变，并表征了随后的视网膜表型。方法。使用PCR从BALB/c和Gnat 2（c.518A>G）视网膜扩增Gnat 2序列，并对产物进行测序。在3、6、9和12个月时使用视网膜电图评估视网膜功能。在3个月和12个月时使用免疫组织化学和定量PCR评估转导蛋白和视蛋白表达。视网膜重塑和米勒细胞胶质增生进行了研究，使用免疫细胞化学。在Gnat 2基因的位置518处的A至G错义突变被鉴定为导致天冬氨酸至甘氨酸取代。Gnat 2（c.518A>G）动物没有显示出视锥反应，而视杆反应是正常的，除了在12个月时光感受器反应降低（a波，-14%）。Gnat 2（c.518A>G）视网膜切片未显示转导蛋白免疫标记;然而，通过Western印迹检测到蛋白质。Gnat 2基因表达仅在12个月大时降低（-27%）。在12个月时视锥细胞数量减少（-27%），M-视蛋白显示出错误定位的证据。3个月时，感光细胞末梢移位，水平细胞、视锥/视杆双极细胞形态改变明显，12个月时，随着Muller细胞胶质细胞增生的出现，感光细胞末梢移位的范围更广。Gnat 2（c.518A>G）小鼠含有错义突变，其由于转导蛋白的错误折叠而导致没有视锥功能。视锥光感受器也显示出视蛋白定位错误、视网膜重塑和变性的迹象。这个自然发生的模型显示了色盲的所有标志性迹象。
PURPOSE. This work investigates a novel, naturally occurring mouse model of achromatopsia. The specific missense mutation within the Gnat2 gene was identified and the subsequent retinal phenotype characterized.METHODS. The Gnat2 sequence was amplified using PCR from BALB/c and Gnat2(c.518A>G) retinae and the product sequenced. Retinal function was assessed at 3, 6, 9, and 12 months using the electroretinogram. Transducin and opsin expression were assessed at 3 and 12 months using immunohistochemistry and quantitative PCR. Retinal remodeling and Muller cell gliosis were investigated using immunocytochemistry.RESULTS. An A to G missense mutation at position 518 of the Gnat2 gene was identified that resulted in an aspartic acid to glycine substitution. Gnat2(c.518A>G) animals showed no cone response, while the rod response was normal except for a decrease in the photoreceptor response at 12 months (a-wave, -14%). Gnat2(c.518A>G) retinal sections showed no transducin immunolabeling; however, protein was detected via Western blot. Gnat2 gene expression was only decreased at 12 months of age (-27%). There was reduced cone number at 12 months (-27%) and M-opsin showed evidence of mislocalization. Displaced photoreceptor terminals and altered horizontal cell, cone/rod bipolar cell morphology were evident at 3 months, becoming more extensive at 12 months with the emergence of Muller cell gliosis.CONCLUSIONS. The Gnat2(c.518A>G) mouse contains a missense mutation that results in no cone function due to a misfolding of transducin. Cone photoreceptors also show signs of opsin mislocalization, retinal remodeling and degeneration. This naturally occurring model shows all the hallmark signs of achromatopsia.