FLVCR1 Deficiency Impairs Mitochondrial Homeostasis in Retinal Degeneration: Choline as a Potential Therapy.

Abstract

BACKGROUND: The Feline Leukaemia Virus Subgroup C Receptor 1 (FLVCR1) has been recognized as a heme exporter essential for erythropoiesis, and emerging research identifies its novel function as a choline transporter. Mutations in FLVCR1 have been associated with the pathogenesis of retinitis pigmentosa (RP); however, the roles of FLVCR1 in retina remain unexplored. This study aims to elucidate the connection between FLVCR1 and RP and investigate potential therapeutic interventions. METHODS: Utilizing CRISPR/Cas9 technology, we established retina-specific Flvcr1 knockout (SKO) and rod-specific Flvcr1 knockout (RKO) mouse models to investigate the in vivo functions of FLVCR1 in the retina. We performed optical coherence tomography (OCT) to assess the retinal thickness, electroretinography (ERG) to test the retinal function and histopathological sections and staining to analyse the pathological changes. Additionally, we administered choline supplementation treatment (CST) to evaluate its potential efficacy in alleviating symptoms of retinal degeneration. RESULTS: Genotyping and immunoblotting analyses confirmed the successful establishment of the SKO and RKO mouse models. Retinal degeneration in SKO mice manifested at postnatal day 14, while its onset in RKO mice occurred at P25, including diminished scotopic electroretinogram (ERG) responses, progressive degeneration of photoreceptor cells, infiltration of microglia into the outer nuclear layer (ONL) and disruption of mitochondrial homeostasis. Notably, we found that choline supplementation in RKO mice alleviated the associated phenotypes. CONCLUSIONS: We developed two innovative mouse models and revealed that FLVCR1 is critical for maintaining mitochondrial homeostasis and supporting photoreceptor survival. Choline supplementation serves as a therapeutic intervention for RP caused by FLVCR1 mutations.