Aug 2026· Human Molecular Genetics· Vol 35 17· 0 citations
Medicine
TL;DR
A new genetic model for studies of splicing-factor associated RP is established that recapitulates aspects of the human disease and suggests that antioxidants might serve as a treatment for individuals with SNRNP200-associated RP.
Abstract
Retinitis Pigmentosa (RP) is an inherited retinal degenerative disease that affects 1 in 4000 individuals worldwide and can lead to complete blindness. Early stages of RP involve death of rod photoreceptors via apoptosis, causing loss of peripheral and night vision, which is followed by death of cone photoreceptors, leading to loss of central and daytime vision. Mutations in over 300 genes cause RP. Many of these genes encode retina-specific proteins; however, some encode globally expressed proteins, such as pre-mRNA splicing factors. This study is focused on mutations in the SNRNP200 gene encoding a core pre-mRNA splicing factor. The pathological mechanisms of SNRNP200-associated RP are not well understood and treatments are limited. An approach to study pathogenic mechanisms is to utilize model organisms. Therefore, we developed Drosophila models in which RP-causing mutations were introduced into the Drosophila melanogaster orthologue Snrnp200. In addition, we used RNAi to knock-down Snrnp200 in the developing eye. Depletion of Snrnp200 caused an adult rough eye phenotype due to apoptosis of cells in the retina. When human RP-causing mutations were modeled in Drosophila Snrnp200, they resulted in abnormal retinal electrophysiology and defective patterning of photoreceptors. Further analysis of the photoreceptors revealed mitochondrial defects and altered expression of genes related to redox homeostasis. Consistent with these changes, treatment with the antioxidant N-acetylcysteine (NAC) partially suppressed the photoreceptor defects. Taken together, these findings established a new genetic model for studies of splicing-factor associated RP that recapitulates aspects of the human disease and suggests that antioxidants might serve as a treatment for individuals with SNRNP200-associated RP.
The hypothesis that there is a biochemical link, most likely the UPR, between rhodopsin folding/misfolding status and metabolic homeostasis is supported and targeted metabolic modulation may offer a complementary therapeutic avenue for treating RP.
M. Murthy, Hannah Staggs-Sandy, Paniz Jasbi et al.· The FASEB Journal· 0 citations
It is suggested that ABCA4 deficiency in photoreceptor discs may trigger early stress-associated transcriptomic responses in retinal glial cells prior to overt photoreceptor degeneration, potentially contributing to Stargardt disease pathogenesis.
Rossella Valenzano, A. McDonald, C. Gallego et al.· Stem Cells· 0 citations
Results identify Cryaa as a critical regulator of ER stress and demonstrate that its reduction promotes UPR activation and subsequent photoreceptor apoptosis in the rd9 model, revealing a key role for Cryaa in XLRP pathology and may provide a novel therapeutic perspective for this disease.
Mingzhu Yang, Ruiqi Qiu, S. Yao et al.· Cell Death & Disease· 0 citations
Purpose Retinitis pigmentosa (RP) is a hereditary retinal disease characterized by progressive photoreceptor cell (PRC) degeneration. WD repeat domain 34 (WDR34), an intermediate chain of dynein-2, is essential for retrograde intraflagellar transport (IFT). However, the mechanisms by which WDR34 deficiency causes retinal degeneration remain unclear. This study aims to investigate the impact of WDR34 deficiency on retrograde IFT and its contribution to retinal degeneration. Methods WDR34 deficiency was modeled in vivo via subretinal injection of adeno-associated virus–shRNA–WDR34 and in vitro by CRISPR/Cas9-mediated knockout in 661W cells. Retinal degeneration and IFT defects were assessed by histologic, functional, and ultrastructural analyses. Proteomic analysis followed by in vivo validation was used to investigate the molecular mechanism underlying WDR34-deficient retinal degeneration. Results WDR34 knockdown induced progressive retinal degeneration characterized by PRC apoptosis, gradual outer nuclear layer thinning, reduced electroretinography responses, and outer segment shortening. WDR34 deficiency impaired retrograde IFT and caused rhodopsin and opsin mislocalization. These alterations induced endoplasmic reticulum stress and unfolded protein response (UPR) activation, activating the IRE1α/TRAF2/NF-κB signaling pathway, ultimately contributing to retinal inflammation and degeneration. Conclusions WDR34 is crucial for maintaining retrograde IFT in PRCs. WDR34 deficiency disrupts outer segment maintenance and triggers UPR-mediated inflammatory responses and apoptosis, ultimately leading to retinal degeneration. This study reveals a novel mechanistic link among WDR34, retrograde IFT, ciliopathies, and retinal degeneration, providing potential therapeutic insights for ciliopathy-associated RP.
Bo Jia, Jianan Xie, Xuebin Zhou et al.· Investigative Ophthalmology...· 0 citations
Central areolar choroidal dystrophy (CACD) is a progressive macular dystrophy without treatment. Although PRPH2 mutations are the most common cause of disease, the mechanisms driving their phenotypic variability remain poorly understood. Here, a comprehensive characterization of the pathophysiological consequences of p.Arg195Leu mutation in PRPH2 was carried out in a mouse model (Prph2
KI/WT
). For evaluating the retinal degeneration, this study combines the analysis of electroretinographic responses together with a complete study of bulk RNA-seq transcriptomics and the key cellular and molecular pathways using confocal imaging, flow-cytometry and western blotting. Results from this work demonstrate that ageing and sex influence retinal degeneration. In young mutant mice, retinal functional impairment and structural disorganization of photoreceptor outer segments were accompanied by a reduced expression of Prph2 and Rom1 genes, together with the activation of the immune system and complement pathways. Middle-age stages represent a critical transition point where the increase of cell death and epithelial barrier dysfunction mark the beginning of retinal degeneration. These pathological events become evident at 9 months of age, where visual pathways-related genes were deregulated. Functional, cellular and molecular alterations observed in the mutant mice do not affect males and females equally. From the earliest stages of the disease, females exhibited greater and sustained inflammatory activation, mainly promoted by complement system upregulation and increased CD11b immunoreactivity, and potentially mediated by IL-6/STAT3/ERK signaling. Moreover, females had greater functional decline and photoreceptor loss. Together, these results could explain the high inter- and intrafamilial variability observed in CACD patients carrying the same mutation. Our findings identify inflammatory biomarkers accompanied by visual function loss, prior to evident retinal degeneration, and demonstrate that age and sex critically shape disease onset and severity. These insights underscore the necessity of incorporating sex-specific biology and early anti-inflammatory treatment into the development of targeted therapies for PRPH2-related dystrophies.
Enola Missonnier, Lorena Vidal-Gil, Carla Sánchez-Castillo et al.· Cell Death Discovery· 0 citations
Summary Inherited retinal diseases (IRDs) encompass a broad spectrum of genetic conditions leading to visual impairment. In this study, we identify KATNA1, encoding the catalytic p60 subunit of the microtubule-severing enzyme katanin, as a previously unrecognized cause of autosomal dominant macular dystrophy (adMD), a form of IRD. Specifically, we could ascertain the presence of 10 heterozygous missense changes affecting six conserved amino acids in 21 individuals from 16 unrelated families from various parts of the world, all presenting with non-syndromic MD of variable severity. Structure-guided analyses indicated that the identified variants potentially disrupt katanin’s assembly into hexamers or its ability to bind or hydrolyze ATP, thus compromising its microtubule-severing function. Characterization of patient-derived fibroblasts revealed accumulation of acetylated microtubules both in the cytoplasm and within the primary cilium, together with an altered subcellular distribution of KATNA1. Immunostaining of human retinal tissue showed that KATNA1 specifically localizes to photoreceptors, with distinct distribution patterns between rod and cone photoreceptors. Immunogold transmission electron microscopy confirmed this finding, revealing KATNA1 distribution along the rod axoneme and predominantly within the cone connecting cilium. Together, these results establish KATNA1 as a novel gene associated with adMD, possibly accounting for ~4% of all unresolved MD cases, and associate defective microtubule severing and cytoskeletal dysregulation with macular degeneration.
Carlo Rivolta, Karolina Kaminska, Abigail R. Moye et al.· Research Square· 0 citations
