# Quantitative Proteomics Identifies Potential Molecular Adaptations in Mouse Models of Congenital Stationary Night Blindness Type 2

## TL;DR

This study uses proteomics to uncover how different genetic mutations in CACNA1F affect retinal proteins and signaling in a mouse model of night blindness.

## Contribution

A novel retinal synapse enrichment protocol enabled detection of low-abundant proteins, revealing variant-specific proteomic adaptations in retinal disease.

## Key findings

- IT retinas show widespread proteomic remodeling, while RX retinas display more restricted changes.
- RX retinas have reduced Cav1.4 levels and synaptic protein changes like Erc1 and Lrfn2.
- Proteomic analysis highlights adaptive responses to calcium channel dysfunction in retinal cells.

## Abstract

Pathogenic variants in the CACNA1F gene are linked to congenital stationary night blindness type 2 though their specific molecular effects remain elusive. This study examines the retinal impact of two variants: a truncation (RX) and a gain-of-function (IT) to explore variant-specific retinal proteome changes. Electroretinography showed that RX primarily affects rod pathways, while IT disrupts both rod and cone signaling, consistent with morphological findings. Comprehensive quantitative proteomic analysis using mass spectrometry identified approximately 4000 proteins across wild-type control and mutant retinas, including also low-abundant membrane proteins. IT retinas exhibited widespread proteomic remodeling suggesting broad cellular responses and also compensatory molecular adaptations. In contrast, RX retinas displayed a more restricted profile. Similar to IT retinas, we found reduced Cav1.4 protein levels but without transcriptional downregulation in RX, alongside selective changes in synaptic proteins such as Erc1, Lrfn2, vGlut1, and Rab3a. These findings suggest selective molecular changes in synaptic organization and calcium-related pathways in RX retinas, offering insights into the mechanisms of Cav1.4 dysfunction in retinal disease. Deep proteomic analysis demonstrates how retinal cells reorganize their molecular architecture in response to calcium channel defects and highlights the utility of comprehensive proteomics to characterize adaptive cellular responses to genetic perturbations in retinal synaptic organization.

•RX causes a milder retinal phenotype compared to IT, with less remodeling and preserved outer nuclear layer integrity.•RX primarily affects rod pathways, while IT disrupts both rod and cone signaling.•Novel retinal synapse enrichment protocol successfully enables detection of Cav1 channel protein.•Proteomic changes occur in both, with IT showing greater protein dysregulation than RX.•RX retinas show reduced Cav1.4 levels and selective synaptic changes, including Erc1 and Lrfn2.

RX causes a milder retinal phenotype compared to IT, with less remodeling and preserved outer nuclear layer integrity.

RX primarily affects rod pathways, while IT disrupts both rod and cone signaling.

Novel retinal synapse enrichment protocol successfully enables detection of Cav1 channel protein.

Proteomic changes occur in both, with IT showing greater protein dysregulation than RX.

RX retinas show reduced Cav1.4 levels and selective synaptic changes, including Erc1 and Lrfn2.

Pathogenic variants in the CACNA1f gene cause congenital stationary night blindness type 2, yet their molecular effects remain unclear. This study compares two variants: a truncation (RX) and a gain-of-function (IT). Proteomic analysis identified ∼4000 proteins, revealing widespread dysregulation in IT retinas and synaptic changes in RX retinas. RX primarily affects rod pathways, while IT disrupts both rod and cone signaling. These findings highlight how proteomics uncovers adaptive molecular responses to calcium channel dysfunction in retinal disease.