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

Research Project

Project/Area Number	18591906
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Single-year Grants
Section	一般
Research Field	Ophthalmology
Research Institution	TOHOKU UNIVERSITY
Principal Investigator	SATO Hajime TOHOKU UNIVERSITY, HOSPITAL, Lecture (10312571)
Co-Investigator(Kenkyū-buntansha)	WAKANA Shigeru TOHOKU UNIVERSTIY, RIKEN, MOUSE Functional Genomics Research Group, Team Reader (90192434) 和田裕子東北大学, 病院・講師 (70302130) 板橋俊隆東北大学, 病院・助手 (20372295)
Project Period (FY)	2006 – 2007
Project Status	Completed (Fiscal Year 2007)
Budget Amount *help	¥3,900,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥300,000) Fiscal Year 2007: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000) Fiscal Year 2006: ¥2,600,000 (Direct Cost: ¥2,600,000)
Keywords	retinal degeneration / Rom1 gene / Peripherin / rds gene / tetramer / 網膜色素変性 / 遺伝子異常 / モデル重物 / モデル動物
Research Abstract	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