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Y. Ueki, M. H. Elliott, L. L. Molday, R. S. Molday, J. D. Ash; Absence of Neuronal Transmission Occurs Prior to the Development of Schisis in a New Mouse Model for X-Linked Juvenile Retinoschisis (Rs1E4E5). Invest. Ophthalmol. Vis. Sci. 2010;51(13):4038. doi: https://doi.org/.
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Mutations in retinoschisin (Rs1), a gene encoding retinoschisin (Rs1), cause a progressive retinal disorder called X-linked juvenile retinoschisis (XLRS) often in young males. Hallmarks of the disease are the splitting of the inner retina (schisis) and reduced retinal function. We have identified a mouse line with a new spontaneous mutation in retinoschisin gene (Rs1E4E5). The purpose was to characterize the mutation and to investigate the role of Rs1 in retinal development and/or maintenance of retinal function.
Western blots and immunohistochemistry were performed to detect Rs1 protein and synaptic marker expression in developing wildtype and Rs1E4E5 retinas. The mutant cDNA was amplified by PCR and sequenced to find potential mutations. Based on the cDNA clones, primers were designed to amplify the RS1 mutant allele in the mouse genome. Morphology and function of the retina were analyzed by histology and electroretinography (ERG).
mRNA and DNA analyses revealed a duplication of Rs1 exons 4 and 5, most likely the result of unequal recombination between two X chromosomes. The mRNA from the Rs1E4E5 allele is expressed, but affected males (Rs1E4E5/ Y)and homozygous females (Rs1E4E5/ E4E5) have no detectable Rs1 protein expression in the retina. Rs1E4E5/ Y or Rs1E4E5/ E4E5 mice have typical inner retinal schisis and no detectable inner retinal function at any age. Our data suggest that synapses develop, but signal transmission to the inner retina does not occur. Data also suggest that schisis occurs subsequent to failure of neuronal transmission.
Analyses showed that this Rs1E4E5 line is another useful model for studying progressive retinal degeneration that occurs in human XLRS. Data suggest that the C-terminus of RS1 is necessary for proper folding and expression in vivo. Our data also suggest that schisis is not likely the cause of transmission defects. Rather, cyst formation and schisis occurs subsequent to the absence of neuronal transmission.
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