B6(A)-Rpe65^rd12/J

Stock number: 005379
Product name: rd12
Research areas: Mouse/Human Gene Homologs, Research Tools, Sensorineural Research

Description

This mutant provides a model for retinitis pigmentosa 20 and Leber congenital amaurosis 2, and is useful in the study of the visual cycle, and has been used successfully in gene therapy experiments.

Detailed description

This mutant provides a model for retinitis pigmentosa 20 and Leber congenital amaurosis. There is slow retinal degeneration as assessed by histology, but rod ERG readings show profoundly diminished dark adapted responses by 1 month of age The light adapted ERG responses at 1 month are delayed and diminished amplitude occurs with age. At 3 months of age the fundus examination appears normal and at 5 months of age small, punctate, white spots appear beneath retinal vessels. At 15 months of age the fundus has a mildly pigmented granular and mottled appearance. Histology of the retina begins to show occasional voids in the outer segments of the photoreceptor cells at approximately 6 weeks of age and at 3 months of age the outer segments have more voids and are more disorganized but the outer segments and the outer nuclear layer remain predominantly intact and relatively normal. However, by 7 months the outer nuclear layer has 6 to 8 layers of outer nuclear layer remaining in the retina and the outer segments are noticeably shorter than normal, and at 27 months only 3 to 4 layers of the outer nuclear layer remain, the outer segments are significantly shorter than normal, and the retinal pigment epithelium is atrophied and hypopigmented. The retinal pigment epithelium shows small lipid-like droplets detectable by electron microscopy at 3 weeks of age and increasing in size and frequency at 3 months of age. Consistent with the disrupted function of RPE65 to convert all-trans retinal to 11-cis retinal, HPLC fails to detect 11-cis-retinal in the retinas of homozygotes, rhodopsin absorbance is not detectable from 2 weeks to 5 months of age, there is reduced opsin levels in retinas as early as 8 days of age, and a progressive increase in retinyl esters after 3 weeks of age.

The spontaneous mutation is a base substitution C-to-T at coding nucleotide 130 resulting in a stop codon instead of arginine at position 44 (p.R44*). Immunostaining reveals that homozygous mutant eyes do not express RPE65 protein.(Chang, 2002)

Development

The recessive Rpe65^rd12 mutation arose spontaneously in a male mouse of strain B6.A-H2-T18^a/BoyEg (Stock No. 001166). This male was bred to a C57BL/6J female and their F1 female offspring were bred back to this male to identify homozygotes. Rpe65^rd12 was then further backcrossed onto C57BL/6J to generate this strain, which was bred to homozygosity and maintained by sibling mating homozygotes since approximately 2005.

The mutation is a base substitution C-to-T at coding nucleotide 130 resulting in a stop codon instead of arginine at position 44 (p.R44*) (PMID: 15765048; Pang, 2005). Immunostaining reveals that homozygous mutant eyes do not express RPE65 protein.(Chang, 2002)

Allele

Symbol: Rpe65^rd12
Name: retinal degeneration 12
MGI accession ID: MGI:2388240
Generation method: Spontaneous
Marker symbol: Rpe65
Marker name: retinal pigment epithelium 65
Chromosome: 3
Strain of origin: B6.A-H2-T18^a/BoyEgJ
Molecular note: This spontaneous mutation was discovered during a routine strain screen at The Jackson Laboratory. Its mapping location suggested it might be an allele of Rpe65, and a point mutation was identified in the Rpe65 gene. The mutation is a base substitution C-to-T at coding nucleotide 130 resulting in a stop codon in stead of arginine at position 44 (p.R44*). Immunostaining revealed that mutant eyes do not express RPE65 protein, and subretinal injection of the AAV5-CBA viral vector expressing human RPE65 significantly rescued the visual phenotype for at least 7 months following treatment.