Plasma Membrane Calcium ATPases Drive Cytoplasmic Acidification and Photoreceptor Degeneration in Retinitis Pigmentosa
4 affiliations
- 1Centro de Investigaciones Biológicas Margarita Salas (CSIC), Madrid, Spain
- 2Cell Biology and Pathology Department, University of Salamanca, Institute for Biomedical Research of Salamanca (IBSAL), Institute of Neurosciences of Castilla y León (INCYL), Salamanca, Spain
- 3Departamento de Bioquímica y Biología Molecular, Facultad de Medicina, Universidad Complutense de Madrid, Spain
- 4Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM) ISCIII, Madrid, Spain
Abstract
Purpose: RP is the most common inherited retinal dystrophy. Limited understanding of how diverse genetic defects converge to cause photoreceptor degeneration hinders the development of mutation-agnostic therapies. Although intracellular Ca²⁺ dysregulation is an early hallmark across genetic variants, its mechanistic link to photoreceptor degeneration remains unclear. This study investigated whether plasma membrane calcium ATPases (PMCA)–mediated Ca²⁺ extrusion induces cytoplasmic acidification that contributes to photoreceptor death in two mouse models of RP.
Methods: PMCA expression (immunofluorescence, RT-qPCR), cytoplasmic acidification (LysoTracker Red [LTR] staining), ultrastructural changes (electron microscopy), calpain-2 activity (in situ zymography) and cell death (TUNEL) were assessed in RP mouse retinas. PMCA-mediated acidification was validated in wild-type (WT) retinal explants under ionophore-induced Ca²⁺ overload. Neuroprotection by PMCA inhibition was evaluated ex vivo (retinal explants) and in vivo (intravitreal injection) by histological photoreceptor preservation.
Results: Retinas from rd10 and homozygous P23H mice exhibited cytoplasmic acidification respect to WT. During the early stages of degeneration, the proportion of acidified photoreceptors (LTR-positive) exceeded that of TUNEL-positive photoreceptors, with LTR staining appearing before the onset of TUNEL labeling. Acidification correlated with PMCA upregulation. Ionophore-induced Ca²⁺ overload recapitulated cytoplasmic acidification ex vivo in WT retinas, which was prevented by PMCA inhibition. In rd10 mice, PMCA inhibition preserved photoreceptors ex and in vivo at different stages.
Conclusions: Our findings identify PMCA as a key mediator of pathological cytoplasmic acidification in RP and improve understanding of mechanisms underlying photoreceptor degeneration, which may facilitate the development of mutation-independent therapies and stage-specific interventions for RP progression.
Related
- Variable clinical course of retinitis pigmentosa patients with RPE65 gene mutations
- The mutational and clinical spectrum of EYS-associated retinitis pigmentosa in an Eastern European and Northern Asian cohort: two recurrent founder alleles
- Unilateral subretinal administration of HORA-PDE6β in patients with retinitis pigmentosa harbouring mutations in the PDE6β gene: study protocol of HORA-PDE6β-001 phase I/II clinical trial.
- Bi-Allelic PRKCZ Loss-of-Function Variants and Adult-Onset Retinitis Pigmentosa
- Generation of retinitis pigmentosa patient-derived hiPSC lines (IDVi007-A, IDVi007-B) carrying the RHO c.68C > A variant (p.P23H) and CRISPR/Cas9-corrected isogenic hiPSC lines (IDVi007-A-1, IDVi007-A-2, IDVi007-A-3)
BibTeX
@article{hernandezpinto2026plasma,
title = {{Plasma Membrane Calcium ATPases Drive Cytoplasmic Acidification and Photoreceptor Degeneration in Retinitis Pigmentosa}},
author = {Alberto M. Hernández-Pinto and Natalia Rodríguez-Muela and Noelia Pimentel-Mayordomo and Patricia Boya and Concepción Lillo and Almudena Sacristán-Reviriego and Enrique J. de la Rosa and Catalina Hernández-Sánchez},
journal = {Investigative Ophthalmology \& Visual Science},
year = {2026},
month = oct,
doi = {10.1167/iovs.67.12.60},
url = {https://doi.org/10.1167/iovs.67.12.60},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - JOUR
TI - Plasma Membrane Calcium ATPases Drive Cytoplasmic Acidification and Photoreceptor Degeneration in Retinitis Pigmentosa
AU - Alberto M. Hernández-Pinto
AU - Natalia Rodríguez-Muela
AU - Noelia Pimentel-Mayordomo
AU - Patricia Boya
AU - Concepción Lillo
AU - Almudena Sacristán-Reviriego
AU - Enrique J. de la Rosa
AU - Catalina Hernández-Sánchez
PY - 2026
DA - 2026/10/23
JO - Investigative Ophthalmology & Visual Science
DO - 10.1167/iovs.67.12.60
UR - https://doi.org/10.1167/iovs.67.12.60
AB - Purpose: RP is the most common inherited retinal dystrophy. Limited understanding of how diverse genetic defects converge to cause photoreceptor degeneration hinders the development of mutation-agnostic therapies. Although intracellular Ca²⁺ dysregulation is an early hallmark across genetic variants, its mechanistic link to photoreceptor degeneration remains unclear. This study investigated whether plasma membrane calcium ATPases (PMCA)–mediated Ca²⁺ extrusion induces cytoplasmic acidification that contributes to photoreceptor death in two mouse models of RP. Methods: PMCA expression (immunofluorescence, RT-qPCR), cytoplasmic acidification (LysoTracker Red [LTR] staining), ultrastructural changes (electron microscopy), calpain-2 activity (in situ zymography) and cell death (TUNEL) were assessed in RP mouse retinas. PMCA-mediated acidification was validated in wild-type (WT) retinal explants under ionophore-induced Ca²⁺ overload. Neuroprotection by PMCA inhibition was evaluated ex vivo (retinal explants) and in vivo (intravitreal injection) by histological photoreceptor preservation. Results: Retinas from rd10 and homozygous P23H mice exhibited cytoplasmic acidification respect to WT. During the early stages of degeneration, the proportion of acidified photoreceptors (LTR-positive) exceeded that of TUNEL-positive photoreceptors, with LTR staining appearing before the onset of TUNEL labeling. Acidification correlated with PMCA upregulation. Ionophore-induced Ca²⁺ overload recapitulated cytoplasmic acidification ex vivo in WT retinas, which was prevented by PMCA inhibition. In rd10 mice, PMCA inhibition preserved photoreceptors ex and in vivo at different stages. Conclusions: Our findings identify PMCA as a key mediator of pathological cytoplasmic acidification in RP and improve understanding of mechanisms underlying photoreceptor degeneration, which may facilitate the development of mutation-independent therapies and stage-specific interventions for RP progression.
SN - 0146-0404
SN - 1552-5783
ER -