Abstract
Purpose::
We previously created knockin mouse models of Pre-RNA Processing Factor (Prpf) related Retinitis Pigmentosa (RP) bearing targeted mutations in Prpf3 and Prpf8 responsible for RP18 and RP13, respectively. These mice have not shown significant photoreceptor degeneration to date. In order to add genetic stress to our models, we intercrossed the mice to create compound knockin Prpf3/Prpf8 mice. We are evaluating the phenotypes of the Prpf3/Prpf8 mutant mice to determine whether the presence of both disease mutations would accelerate photoreceptor degeneration.
Methods::
Heterozygous Prpf8 knockin mice were crossed to homozygous Prpf3 knockin mice to generate compound heterozygous Prpf3/Prpf8 mice. The compound heterozygous Prpf3/Prpf8 mice were then intercrossed to produce litters with all the possible ratios of wild-type, heterozygous Prpf3 or Prpf8, homozygous Prpf3 or Prpf8, compound heterozygous Prpf3/Prpf8, and compound homozygous Prpf3/Prpf8 knockin mice. Genotypes were identified by PCR based assays. The mice were aged, and retinal status evaluated using electroretinography (ERG) and histology.
Results::
Compound heterozygous Prpf3/Prpf8 mice were identified, and were healthy and fertile. At up to 7 months of age, compound heterozygous mice have normal visual function based on ERG analysis. No compound homozygous Prpf3/Prpf8 mice have been obtained to date, however, compound knockin mice homozygous for Prpf3 and heterozygous for Prpf8, and vice versa, have been obtained. ERG recordings from these mice show no difference compared to wild-type at up to 5 months.
Conclusions::
The compound knockin Prpf3/Prpf8 mutations appear not to affect the retina of mice at timepoints up to 7 months. Continued evaluation of these mice at additional timepoints will be carried out, followed by histological analysis. Additionaly, no compound homozygous Prpf3/Prpf8 mice have been obtained to date. Continued Breeding is in progress to determine if compound homozygous mutations cause embryonic lethality.
Keywords: retinal degenerations: hereditary • retinal degenerations: cell biology • transgenics/knock-outs