Abstract
Purpose :
Mutations in genes crucial for photoreceptor function can lead to photoreceptor cell death in Retinitis Pigmentosa (RP). Defining the common pathways disrupted across genes is crucial if we are to develop therapies in a gene-agnostic way. The purpose of this study was to interrogate mice harbouring a mutation in the Pde6b gene at different timepoints to identify pathways contributing to cell stress and death.
Methods :
Experiments were performed with Pde6batrd2 mice and wild-type littermates with at least 3 replicates per timepoint. In vivo phenotyping experiments included electroretinography (ERG) examinations, optokinetic response (OKR) tests and optical coherence tomography (OCT) images. Outer nuclear layer (ONL) thickness (H&E sections) was used to identify early and late timepoints for performing single cell RNA sequencing (scRNA-seq) experiments. For each timepoint, dissociated retinas of mutant (N=3) and control (N=3) littermates were used. Data analysis was performed using R statistical programming language.
Results :
ERGs showed a significant reduction in photoreceptor function by P18, impaired visual acuity was detectable in OKR tests by P21, and no photoreceptor layer was detectable in OCT images at P28. Histology analyses showed ONL thinning starting from P15, with 50% ONL remaining at P18 and almost total loss at P28. Further scRNA-seq analyses revealed similar photoreceptor expression profiles between mutant and wild-type at P13, but distinct transcriptional profiles at P18.
Conclusions :
Our results show an early and rapid photoreceptor degeneration in the Pde6batrd2 mouse beginning as soon as the mouse opens its eyes and progressing rapidly, resulting in loss of retinal function. Further analyses of scRNA-seq data will offer key insight into the mechanism that triggers photoreceptor death in PDE6B-mediated RP.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.