Molecular mechanism of dominant retinal degeneration in mice resulted from a point mutation in the Rom1 gene.

视网膜变性小鼠的突变被命名为Rom1^&lt；Rgsc1156&gt；是一种可能的错义突变，导致翻译蛋白第182位的Trp替换为Arg。密码子182位于Rom1的盘内环，盘内环已被证明在由Rom1和/或Peropherin/rds组成的四聚体的形成中发挥重要作用。3周龄时，光感受器的外核层厚度和内外节段长度变化不大，进行免疫组织化学和Western印迹分析。免疫组织化学分析显示，杂合子小鼠的Rom1免疫反应性较野生型小鼠降低。在纯合子中，免疫反应性明显降低。此外，在杂合子和纯合子中，外周蛋白/Rds的免疫反应性也降低。Western blotts的密度定量分析演示…此外，Rom1杂合子和纯合子小鼠的Rom1免疫反应性分别为野生型小鼠的51.6%和2.8%。另一方面，发现Rgsc1156和Rgsc1156杂合子和纯合子的外周蛋白/rds的免疫反应性分别是野生型小鼠的59.3%和17.4%。这些结果与Kedzierski的结果一致，即如果Rom1和外周蛋白/rds的结合丰度降低到野生型小鼠的60%左右，就可能发生视网膜退化。Rom1^；；Rgsc1156&gt；杂合子的视网膜退化程度与由于外周蛋白/rds单倍体不足而导致的rds/+小鼠相似，这表明突变体Rom1诱导的野生型Rom1和外周蛋白/rds水平的降低导致了Rom1^&lt；Rgsc1156&gt；小鼠的视网膜退化。免疫组织化学结果表明，突变的Rom1-外周蛋白/rds异构体和突变的Rom1同源异构体在亚基组装后立即降解，这是因为突变的Rom1和外周蛋白/rds在突变体的内段几乎没有免疫反应，而且外段的两种蛋白的免疫反应性都降低了，这是一种基因依赖的方式。需要对含有突变体Rom1的四聚体的形成和稳定性进行体外分析。较少

The mutation of retinal degeneration mouse, which is designated as Rom1^<Rgsc1156>, was putative missense mutation that caused Trp to Arg substitution at position 182 of the translated protein. The codon 182 is located in the intradiscal loop of Rom1, and the intradiscal loop has been shown to play an important role in the formation of tetramers which is composed of Rom1 and/or Peropherin/rds. We performed immunohistochemistry and Western blot using the samples at 3 weeks of age, when there is little alteration of the thickness of outer nuclear layer and the length of inner and outer segments of photoreceptors. The immunohistochemical analysis revealed that the immunoreactivity for Rom1 was decreased in heterozygotes compared to that of wild-type mice. In homozygotes, the immunoreactivity was markedly reduced. In addition, the immunoreactivity for Peripherin/Rds was also decreased in heterozygotes and homozygotes.Semi-quantitative analysis for Western blots using densitometry demonstra … More ted that the immunoreactivity for Rom1 in the Rom1^<Rgsc1156> heterozygotes and homozygotes were 51.6% and 2.8% of that in wild-type mice. On the other hand, it showed that the immunoreactivity for Peripherin/rds in the Rom1^<Rgsc1156> heterozygotes and homozygotes were 59.3% and 17.4% of that in wild-type mice. These results are compatible with the results by Kedzierski that retinal degeneration could happen if the combined abundance of Rom1 and Peripherin/rds was decreased to about 60% of that in wild-type mice.The degree of retinal degeneration in Rom1^<Rgsc1156> hetrozygotes is similar to that in rds/+mice which resulted from Peripherin/rds haploinsufficiency, suggesting that the decreased levels of wild-type Rom1 and Peripherin/rds induced by mutant Rom1 caused the retinal degeneration in Rom1^<Rgsc1156> mice. The results of immunohistochemistry implied that the mutant Rom1-Peripherin/rds heterotetramers and the mutant Rom1 homotetramers degraded immediately after the subunit assembly because there was little immunoreactivity of both Rom1 and Peripherin/rds in the inner segment of the Rom1^<Rgsc1156> mutants and because there was decreased immunoreactivity of both proteins in the outer segment in genotype-dependent manner. In vitro analysis for the formation and stability of the tetramers containing mutant Rom1 will be needed. Less