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M. Miyamoto, M. Aoki, S. Sugimoto, K. Kawasaki, R. Imai; Identification of Intronic Mutation of Rod Transducin Gene in Naturally Occurring Retinal Dysfunction Mice. Invest. Ophthalmol. Vis. Sci. 2007;48(13):2992.
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© ARVO (1962-2015); The Authors (2016-present)
IRD (ICR-derived retinal dysfunction) 1 and IRD2 mice are naturally occurring mouse mutants showing retinal dysfunction. Both mutants show rod dysfunction and IRD1 mice also simultaneously exhibit cone dysfunction. Genetic analysis revealed that rod function in these mutants was affected by a mutation in the same gene. The purpose of this study is to determine the cause of rod dysfunction in the mutants.
The light-dependent translocation of rod transducin α-subunit (Trα) and rod arrestin (Arr) was examined with immunohistochemistry. Sequence analysis of Trα cDNA and genomic DNA was performed. Protein expressions were investigated using Western blot analysis.
In the immunohistochemical analysis, Trα signals were undetectable in the mutants regardless of the light condition, while Arr showed normal light-dependent translocation. Sequencing of Trα cDNA in the mutants revealed a 48-basepair (bp) insertion between exon 4 and exon 5. This insertion changed codon 149 TAC to a stop codon TAG (Tyr149Ter). A 57-bp deletion was identified in intron 4 in Trα genomic DNA in the mutants, and the deletion included the last 2 bases of the first 6 in its splice donor site, suggesting that the genomic DNA alteration is related to the cDNA insertion. There were no Trα-immunoreactive bands in protein extracts from retinas of the mutants even using a primary antibody recognizing the N-terminus of the Trα protein.
The cause of rod dysfunction in IRD1 and IRD2 mice was considered to be an intronic mutation in the Trα gene.
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