Abstract
Purpose :
Purpose: The FAM161A-p.Arg523* mutation is the most frequent premature termination codon causing retinitis pigmentosa (RP) in the Israeli Jewish population. Our major aim is to generate and characterize a KI mouse model for this mutation and evaluate its outcome on retinal function and structure.
Methods :
Methods: Homozygous knock-in (KI) mice for the p.Arg512* mutation, which corresponds to the human p.Arg523* mutation, were generated by Cyagen Biosciences. Retinal function and structure were examined at the ages of 1 through 21 months (in a 3-months interval) using visual acuity (VA), electroretinography (ERG), optical coherence tomography (OCT), fundus autofluorescence (FAF) imaging, histological and immunohistochemical (IHC) analysis.
Results :
Results: Visual acuity analysis showed gradual decrease at the ages 1 to 21 months. Evaluation of retinal function by ERG revealed a progressive decrease in rod and cone amplitudes as compared with WT mice from 1 to 21 months, and a flat response at 21 months. Anatomical structure of the retina, examined by OCT, revealed total loss of outer nuclear layer (ONL) at the age of 21 months, which was first evident at 3 months. Funduscopy examination revealed narrowing of the blood vessels and patchy hyperautofluorescent spots, indicating widespread retinal degeneration. Histological analysis showed progressive loss of photoreceptor nuclei in the ONL but a few nuclei were still evident even in relatively old ages. IHC staining demonstrated reduced and diffused Fam161a expression in the KI comparted to the wildtype retina.
Conclusions :
Conclusions: The outcome of the study evidently indicate that the homozygous p.Arg512* mutation has an impact on retinal function and leads to retinal degeneration in the KI mice. Unexpectedly, the rate of photoreceptor loss in the KI model is much slower than in the FAM161A knockout model we previously characterized. In a parallel in vitro study, we provided evidence for the positive significant effect of ataluren on the ability of FAM161A-p.Arg523* patient-derived fibroblasts to grow cilia. Therefore, the KI mouse model can serve as a suitable model to test this therapeutic modality in vivo as well as other modalities such as gene augmentation therapy and RNA editing.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.