RNA-seq reveals differential expression genes related to visual cycle in Prph2 knock-in mice

Abstract

Purpose : A point mutation in Prph2 gene triggers Central Aerolar Choroidal Dystrophy (CACD), which is characterized by a progressive photoreceptor degeneration, leading to blindness. CRISPR/Cas9 system was used to generate a Prph2 WT/KI mice model by introducing a point mutation Arg195Leu in Prph2 gene, mimicking the human pathology. Here, we aim to evaluate the transcriptomic profile of Prph2 WT/KI mice and specifically to investigate the expression pattern of genes involved in visual pathways.

Methods : Male and females Prph2 WT/KI and Prph2 WT/WT (control) at different ages were included. Electroretinographic recordings (ERG) were used to evaluate the electrical response to light stimulus of retinas from Prph2 WT/WT and Prph2 WT/KI mice. The neural retina from the same mice were used to perform transcriptomic analysis by total RNA sequencing. Differential expression analysis between specified groups was performed using DESeq2. Genes with adjusted P value (< 0.05) and log2 fold change (≥ 1.0 or ≤ −1.0) were labelled as differentially expressed genes for each comparison. According to these results, enrichment analysis for biological processes and function pathways affected was performed in EnrichR website. Visualization of pathway enrichment analysis were performed using R ggplot2 package.

Results : Impaired visual function was registered in Prph2WT/KI compared to control mice in an age-dependent manner. The a- and b-wave values registered in ERG responses began to decrease after 6 months of age in Prph2 WT/KI compared to Prph2 WT/WT. However, the RNA-seq data shows that visual cycle related genes such as RPE65, Rho and L-rat were already deregulated from the first month of birth in Prph2WT/KI compared to Prph2WT/WT. This gene deregulation becomes more evident across the age when the electrical response of the retina is already greatly impaired.

Conclusions : Although the impairment of visual function in Prph2 WT/KI mice only appears from 6 six-month age, earlier alterations in the expression pattern of genes involved in visual cycle were detected.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.