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Simvastatin Protects Photoreceptors from all-trans-retinal Induced Oxidative Stress with Up-regulation of Interphotoreceptor Retinoid Binding Protein
摘要： Background and Purpose Simvastatin is a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor with multiple targets and effects. It protects neurons in the brain but its protective effects on photoreceptors are unclear. In this study, we evaluated the neuroprotective effect of simvastatin on photoreceptors exposed to stress induced by all-trans-retinal (atRAL). Experimental approach AlamarBlue and lactate dehydrogenase assays were used to evaluate the viability and metabolic activity of Y79 cells (a retinoblastoma cell line) exposed to atRAL-induced stress with or without simvastatin pre-treatment. Changes in cellular reactive oxygen species were evaluated using flow cytometry and mitochondrial stress markers JC-1 and HSP60. Changes in levels of the photoreceptor-specific markers cone-rod homeobox protein (CRX) and Interphotoreceptor Retinoid Binding Protein (IRBP) were evaluated with Western blotting. The results were validated in ex vivo human retinal explants and a mouse model of photoreceptor degeneration. Key results Simvastatin improved mitochondrial function, alleviated oxidative stress and upregulated the photoreceptor specific markers IRBP and its upstream regulator CRX in Y79 cells and ex vivo human retinal explants under atRAL-induced stress. Simvastatin attenuated photoreceptor degeneration in association with upregulation of IRBP and CRX expression after knockdown of IRBP in a murine model. Conclusion and implications Our findings suggest that simvastatin has a novel role in protecting photoreceptors from atRAL-induced stress. Simvastatin treatment resulted in upregulation of IRBP and its upstream transcription factor CRX in Y79 cells, ex vivo human retinal explants and murine retinas in vivo. Further studies of simvastatin to treat photoreceptor degeneration are warranted.
关键词： photoreceptors,IRBP,CRX,oxidative stress,all-trans-retinal,Simvastatin
更新于2025-11-21 11:08:12
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A novel CRX variant (p.R98X) is identified in a Chinese family of Retinitis pigmentosa with atypical and mild manifestations
摘要： Background Retinitis pigmentosa (RP) is the most common form of hereditary retinal degeneration that can cause inherited blindness. RP has extreme genetic and clinical heterogeneity, which brings a major obstacle to obtaining an accurate molecular diagnosis. Objective To analyze the genetic defect in a Chinese family of RP with a few atypical manifestations. Methods Whole-exome sequencing (WES) was applied to identify the disease-associated genes. Sanger sequencing was performed to validate the variants of candidate genes in the patient and his parents. In vitro expression analysis was further conducted to examine the potential biological function of the gene variant. Results A heterozygous nonsense variant c.292C > T (p.R98X) of CRX gene was identified to be present in the affected male. The c.292C > T variant of CRX was absent in all of the searched databases, including the 10,000 Chinese exome database. The nonsense variant was supposed to result in a truncated CRX protein with a destroyed homedomain (HD), which is essential for CRX translation. Interestingly, the following assay showed that the potential truncated protein was not detected, indicating that the variant may cause a loss-of-function mutation of CRX gene. Conclusion We identified a novel heterozygous null mutation in the CRX gene which was the first evidence of a nonsense mutation in the HD domain of CRX. Our finding suggested that the haploinsufficiency mutation of CRX gene contributed to the atypical and mild manifestations of the autosomal dominant RP in the Chinese family.
关键词： Retinitis pigmentosa (RP),Nonsense mutation,Whole exome sequence,CRX
更新于2025-09-11 14:15:04
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Targeted deletion of an NRL- and CRX-regulated alternative promoter specifically silences FERM and PDZ domain containing 1 ( <i>Frmpd1</i> ) in rod photoreceptors
摘要： Regulation of cell type-specific gene expression is critical for generating neuronal diversity. Transcriptome analyses have unraveled extensive heterogeneity of transcribed sequences in retinal photoreceptors because of alternate splicing and/or promoter usage. Here we show that Frmpd1 (FERM and PDZ domain containing 1) is transcribed from an alternative promoter specifically in the retina. Electroporation of Frmpd1 promoter region, -505 to +382 bp, activated reporter gene expression in mouse retina in vivo. A proximal promoter sequence (-8 to +33 bp) of Frmpd1 binds to NRL and CRX, two rod-specific differentiation factors, and is necessary for activating reporter gene expression in vitro and in vivo. CRISPR/Cas9-mediated deletion of the genomic region including NRL and CRX binding sites in vivo completely eliminated Frmpd1 expression in rods and dramatically reduced expression in rod bipolar cells, thereby overcoming embryonic lethality caused by germline Frmpd1 deletion. Our studies demonstrate that a cell-type-specific regulatory control region is a credible target for creating loss-of-function alleles of widely-expressed genes.
关键词： rod photoreceptors,Frmpd1,NRL,CRX,alternative promoter,CRISPR/Cas9
更新于2025-09-10 09:29:36