Light-induced Retinal Damage Research Articles

Targeting ferroptosis: a novel therapeutic strategy for the treatment of retinal diseases.

Ferroptosis plays a vital role in the progression of various retinal diseases. The analysis of the mechanism of retinal cell ferroptosis has brought new targeted strategies for treating retinal vascular diseases, retinal degeneration and retinal nerve diseases, and is also a major scientific issue in the field of ferroptosis. In this review, we summarized results from currently available in vivo and in vitro studies of multiple eye disease models, clarified the pathological role and molecular mechanism of ferroptosis in retinal diseases, summed up the existing pharmacological agents targeting ferroptosis in retinal diseases as well as highlighting where future research efforts should be directed for the application of ferroptosis targeting agents. This review indicates that ferroptosis of retinal cells is involved in the progression of age-related/inherited macular degeneration, blue light-induced retinal degeneration, glaucoma, diabetic retinopathy, and retinal damage caused by retinal ischemia-reperfusion via multiple molecular mechanisms. Nearly 20 agents or extracts, including iron chelators and transporters, antioxidants, pharmacodynamic elements from traditional Chinese medicine, ferroptosis-related protein inhibitors, and neuroprotective agents, have a remissioning effect on retinal disease in animal models via ferroptosis inhibition. However, just a limited number of agents have received approval or are undergoing clinical trials for conditions such as iron overload-related diseases. The application of most ferroptosis-targeting agents in retinal diseases is still in the preclinical stage, and there are no clinical trials yet. Future research should focus on the development of more potent ferroptosis inhibitors, improved drug properties, and ideally clinical testing related to retinal diseases.

Prevention of Sunlight-Induced Cell Damage by Selective Blue-Violet-Light-Filtering Lenses in A2E-Loaded Retinal Pigment Epithelial Cells.

Blue light accelerates retinal aging. Previous studies have indicated that wavelengths between 400 and 455 nm are most harmful to aging retinal pigment epithelia (RPE). This study explored whether filtering these wavelengths can protect cells exposed to broad sunlight. Primary porcine RPE cells loaded with 20 µM A2E were exposed to emulated sunlight filtered through eye media at 1.8 mW/cm2 for 18 h. Filters selectively filtering out light over 400-455 nm and a dark-yellow filter were interposed. Cell damage was measured by apoptosis, hydrogen peroxide (H2O2) production, and mitochondrial membrane potential (MMP). Sunlight exposure increased apoptosis by 2.7-fold and H2O2 by 4.8-fold, and halved MMP compared to darkness. Eye Protect SystemTM (EPS) technology, filtering out 25% of wavelengths over 400-455 nm, reduced apoptosis by 44% and H2O2 by 29%. The Multilayer Optical Film (MOF), at 80% of light filtered, reduced apoptosis by 91% and H2O2 by 69%, and increased MMP by 73%, overpassing the dark-yellow filter. Photoprotection increased almost linearly with blue-violet light filtering (400-455 nm) but not with total blue filtering (400-500 nm). Selective filters filtering out 25% (EPS) to 80% (MOF) of blue-violet light offer substantial protection without affecting perception or non-visual functions, making them promising for preventing light-induced retinal damage with aesthetic acceptance for permanent wear.

Protective Effects of Purple Corn (Zea mays L.) Byproduct Extract on Blue Light-Induced Retinal Damage in A2E-Accumulated ARPE-19 Cells.

This study investigated the antioxidative characteristics of Zea mays L. purple corn cob and husk extract (PCHE) and its potential protective effects against blue light (BL)-induced damage in N-retinylidene-N-retinylethanolamine (A2E)-accumulated ARPE-19 retinal pigment epithelial cells. PCHE had a 2,2-diphenyl-1-picrylhydrazyl radical-scavenging capacity and Trolox equivalent antioxidant capacity of 1.28±0.43 mM Trolox equivalents (TE)/g and 2,545.41±34.13 mM TE/g, respectively. Total content of anthocyanins, polyphenols, and flavonoids in the PCHE was 11.13±0.10 mg cyanidin-3-glucoside equivalents/100 g, 227.90±7.38 mg gallic acid equivalents/g, and 117.75±2.46 mg catechin equivalents/g, respectively. PCHE suppressed the accumulation of A2E and the photooxidation caused by BL in a dose-dependent manner. After initial treatment with 25 µM/mL A2E and BL, ARPE-19 cells showed increased cell viability following additional treatment with 15 µg/mL PCHE while the expression of the p62 sequestosome 1 decreased, whereas that of heme oxygenase-1 protein increased compared with that in cells without PCHE treatment. This suggests that PCHE may slow the autophagy induced by BL exposure in A2E-accumulated retinal cells and protect them against oxidative stress.

Effect of hydrogen-rich saline on melanopsin after acute blue light-induced retinal damage in rats.

Excessive exposure to blue light can cause retinal damage. Hydrogen-rich saline (HRS), one of the hydrogen therapies, has been demonstrated to be effective in eye photodamage, but the effect on the expression of melanopsin in intrinsically photosensitive retinal ganglion cells (ipRGCs) is unknown. In this study, we used a rat model of light-induced retinal injury to observe the expression of melanopsin after HRS treatment and to determine the effect of HRS on retinal ganglion cell protection. Adult SD rats were exposed to blue light (48 h) and treated with HRS for 0, 3, 7, and 14 days. Real-time polymerase chain reaction (qRT-PCR) and Western blotting (WB) were performed to find the expression of genes and proteins, respectively. The function of retinal ipRGCs was measured by pattern-evoked electroretinography (pERG). The number and morphological changes of melanopsin-positive ganglion cells in the retina were observed by immunofluorescence (IF). Acute blue light exposure caused a decrease in ipRGC function, decreased expression of melanopsin protein and the melanopsin-positive RGCs, and diminished immunoreactivity in dendrites. However, over time, melanopsin showed a tendency to self-recovery, with an increase in melanopsin protein expression and the number of melanopsin-positive RGCs, with incomplete recovery of function within two weeks. HRS treatment accelerated the recovery process, with a significant increase in melanopsin expression and the number of melanopsin-positive RGCs, and an improvement in the pERG waveform within two weeks.

Halofuginone prevents outer retinal degeneration in a mouse model of light-induced retinopathy.

Photoreceptor cell death can cause progressive and irreversible visual impairments. Still, effective therapies on retinal neuroprotection are not available. Hypoxia-inducible factors (HIFs) are transcriptional factors which strongly regulate angiogenesis, erythropoiesis, intracellular metabolism, and programed cell death under a hypoxic or an abnormal metabolic oxidative stress condition. Therefore, we aimed to unravel that inhibition of HIFs could prevent disease progression in photoreceptor cell death, as recent studies showed that HIFs might be pathologic factors in retinal diseases. Adult male balb/cAJcl (8 weeks old; BALB/c) were used to investigate preventive effects of a novel HIF inhibitor halofuginone (HF) on a murine model of light-induced retinopathy. After intraperitoneal injections of phosphate-buffered saline (PBS) or HF (0.4 mg/kg in PBS) for 5 days, male BALB/c mice were subjected to a dark-adaption to being exposed to a white LED light source at an intensity of 3,000 lux for 1 hour in order to induce light-induced retinal damage. After extensive light exposure, retinal damage was evaluated using electroretinography (ERG), optical coherence tomography (OCT), and TUNEL assay. Light-induced retinal dysfunction was suppressed by HF administration. The amplitudes of scotopic a-wave and b-wave as well as that of photopic b-wave were preserved in the HF-administered retina. Outer retinal thinning after extensive light exposure was suppressed by HF administration. Based on the TUNEL assay, cell death in the outer retina was seen after light exposure. However, its cell death was not detected in the HF-administered retina. Halofuginone was found to exert preventive effects on light-induced outer retinal cell death.

Molecular Mechanism Analysis of Intensive Light-Induced Retinal Damages.

Introduction: The retina is a light-sensitive tissue, and intensive light exposure leads to light-induced retinal damage. It is pointed out that photoreceptor damage is responsible for the decrease in retina function. The aim of this study was to detect the main genes and biological terms which are involved in retinal response to intensive light exposure. Methods: The effect of intensive light on the mouse retina function was searched in the Gene Expression Omnibus (GEO) database. The data of GSE22818 were assessed by the GEO2R program. The significant differentially expressed genes (DEGs) were determined and evaluated via directed protein-protein interaction (PPI) network analysis. The critical significant DEGs were enriched via gene ontology analysis to find the related biological processes, molecular function, and biochemical pathways. Results: Data analysis indicates that the high intensity of light induces gene expression alteration in the retina. 105 significant DEGs were identified as the main responsive genes to light damage in the retina. STAT3, JUN, IL6ST, SOCS3, ATF3, JUNB, FOSL1, CCL2, ICAM1, FGF2, AGT, MYC, LIF, CISH, and EGR1 were introduced as the critical affected genes. STAT3, JUN, IL6ST, SOCS3, and ATF3 and "Positive regulation of the receptor signaling pathway via JAK-STAT" were highlighted as the key elements of molecular events. Conclusion: It can be concluded that regulation of the key DEGs and the dependent biological terms can effectively provide tools to prevent the development of light-induced retinal damage.

Fullerol rescues the light-induced retinal damage by modulating Müller glia cell fate

Excessive light exposure can damage photoreceptors and lead to blindness. Oxidative stress serves a key role in photo-induced retinal damage. Free radical scavengers have been proven to protect against photo-damaged retinal degeneration. Fullerol, a potent antioxidant, has the potential to protect against ultraviolet-B (UVB)-induced cornea injury by activating the endogenous stem cells. However, its effects on cell fate determination of Müller glia (MG) between gliosis and de-differentiation remain unclear. Therefore, we established a MG lineage-tracing mouse model of light-induced retinal damage to examine the therapeutic effects of fullerol. Fullerol exhibited superior protection against light-induced retinal injury compared to glutathione (GSH) and reduced oxidative stress levels, inhibited gliosis by suppressing the TGF-β pathway, and enhanced the de-differentiation of MG cells. RNA sequencing revealed that transcription candidate pathways, including Nrf2 and Wnt10a pathways, were involved in fullerol-induced neuroprotection. Fullerol-mediated transcriptional changes were validated by qPCR, Western blotting, and immunostaining using mouse retinas and human-derived Müller cell lines MIO-M1 cells, confirming that fullerol possibly modulated the Nrf2, Wnt10a, and TGF-β pathways in MG, which suppressed gliosis and promoted the de-differentiation of MG in light-induced retinal degeneration, indicating its potential in treating retinal diseases.

Discovery of Nonretinoid Inhibitors of CRBP1: Structural and Dynamic Insights for Ligand-Binding Mechanisms.

The dysregulation of retinoid metabolism has been linked to prevalent ocular diseases including age-related macular degeneration and Stargardt disease. Modulating retinoid metabolism through pharmacological approaches holds promise for the treatment of these eye diseases. Cellular retinol-binding protein 1 (CRBP1) is the primary transporter of all-trans-retinol (atROL) in the eye, and its inhibition has recently been shown to protect mouse retinas from light-induced retinal damage. In this report, we employed high-throughput screening to identify new chemical scaffolds for competitive, nonretinoid inhibitors of CRBP1. To understand the mechanisms of interaction between CRBP1 and these inhibitors, we solved high-resolution X-ray crystal structures of the protein in complex with six selected compounds. By combining protein crystallography with hydrogen/deuterium exchange mass spectrometry, we quantified the conformational changes in CRBP1 caused by different inhibitors and correlated their magnitude with apparent binding affinities. Furthermore, using molecular dynamic simulations, we provided evidence for the functional significance of the "closed" conformation of CRBP1 in retaining ligands within the binding pocket. Collectively, our study outlines the molecular foundations for understanding the mechanism of high-affinity interactions between small molecules and CRBPs, offering a framework for the rational design of improved inhibitors for this class of lipid-binding proteins.

REG1A protects retinal photoreceptors from blue light damage.

With the increased use of artificial light and the prolonged use of optoelectronic products, light damage (LD) to the human retina has been identified as a global vision-threatening problem. While there is evidence of a significant correlation between light-induced retinal damage and age-related vision impairment in age-related macular degeneration, it is unclear how light-induced retinal degeneration manifests itself and whether there are agents capable of preventing the development of LD in the retina. This study investigated a mechanism by which blue light leads to photoreceptor death. By observing blue light exposure in retinal organoids and photoreceptor cells, we concluded that there could be significant apoptosis of the photoreceptors. We demonstrate that regenerating islet-derived 1 alpha (REG1A) prevents photoreceptors from undergoing this LD-induced apoptosis by increasing expression of the anti-apoptotic gene Bcl2 and downregulating expression of the pro-apoptotic gene Bax, resulting in reduced mitochondrial damage and improved aerobic capacity in photoreceptor cells. For the first time, REG1A has been shown to restore mitochondrial function and cell apoptosis after LD-induced damage, suggesting its potential application in the prevention and treatment of retinal vision loss.

A small molecule compound that inhibits blue light-induced retinal damage via activation of autophagy

Dry age-related macular degeneration (AMD) is a type of disease that causes visual impairment due to changes in the macula located in the center of the retina. The accumulation of drusen under the retina is also a characteristic of dry AMD. In this study, we identified a compound (JS-017) that can potentially degrade N-retinylidene-N-retinylethanolamine (A2E), one of the components of lipofuscin, using fluorescence-based screening, which measures A2E degradation in human retinal pigment epithelial cells. JS-017 effectively degraded A2E in ARPE-19 cells and consequently suppressed the activation of the NF-κB signaling pathway and expression of inflammatory and apoptosis genes induced by blue light (BL). Mechanistically, JS-017 induced LC3-II formation and improved autophagic flux in ARPE-19 cells. Additionally, the A2E degradation activity of JS-017 was found to be decreased in autophagy-related 5 protein-depleted ARPE-19 cells, suggesting that autophagy was required for A2E degradation mediated by JS-017. Finally, JS-017 exhibited an improvement in BL-induced retinal damage measured through fundus examination in an in vivo retinal degeneration mouse model. The thickness of the outer nuclear layer and inner/external segments, which was decreased upon exposure to BL irradiation, was also restored upon JS-017 treatment. Altogether, we demonstrated that JS-017 protected human retinal pigment epithelium (RPE) cells from A2E and BL-induced damage by degrading A2E via the activation of autophagy. The results suggest the feasibility of a novel A2E-degrading small molecule as a therapeutic agent for retinal degenerative diseases.

Modulating the Kynurenine pathway or sequestering toxic 3-hydroxykynurenine protects the retina from light-induced damage in Drosophila.

Tissue health is regulated by a myriad of exogenous or endogenous factors. Here we investigated the role of the conserved Kynurenine pathway (KP) in maintaining retinal homeostasis in the context of light stress in Drosophila melanogaster. cinnabar, cardinal and scarlet are fly genes that encode different steps in the KP. Along with white, these genes are known regulators of brown pigment (ommochrome) biosynthesis. Using white as a sensitized genetic background, we show that mutations in cinnabar, cardinal and scarlet differentially modulate light-induced retinal damage. Mass Spectrometric measurements of KP metabolites in flies with different genetic combinations support the notion that increased levels of 3-hydroxykynurenine (3OH-K) and Xanthurenic acid (XA) enhance retinal damage, whereas Kynurenic Acid (KYNA) and Kynurenine (K) are neuro-protective. This conclusion was corroborated by showing that feeding 3OH-K results in enhanced retinal damage, whereas feeding KYNA protects the retina in sensitized genetic backgrounds. Interestingly, the harmful effects of free 3OH-K are diminished by its sub-cellular compartmentalization. Sequestering of 3OH-K enables the quenching of its toxicity through conversion to brown pigment or conjugation to proteins. This work enabled us to decouple the role of these KP genes in ommochrome formation from their role in retinal homeostasis. Additionally, it puts forward new hypotheses on the importance of the balance of KP metabolites and their compartmentalization in disease alleviation.

Blueberry stem extract and stem active components prevent blue light-emitting diode light-induced retinal photoreceptor cell damage in vitro.

Blue light causes retinal damage that can lead to ocular diseases such as age-related macular degeneration. In this study, we determined the protective effect of blueberry stem extract (BStEx) and active components on blue light-emitting diode (LED) light-induced retinal photoreceptor cell damage in vitro. Photoreceptor cells cultured in the presence of BStEx or components were exposed to blue light to induce cell damage. BStEx, fractions of BStEx containing proanthocyanidins, chlorogenic acid, catechin, and epicatechin prevented the cell damage and/or inhibited the generation of reactive oxygen species (ROS). Furthermore, BStEx reduced apoptosis and cell death, and inhibited the phosphorylation of p38 mitogen-activated protein kinase and c-Jun N-terminal kinase leading to cellular apoptosis induced by blue light exposure. These findings suggest that BStEx and components exert a protective effect against blue light-induced photoreceptor cell damage through the inhibition of MAPK phosphorylation and ROS production.

SRY-box transcription factor 9 modulates Müller cell gliosis in diabetic retinopathy by upregulating TXNIP transcription.

Diabetic retinopathy (DR), a common complication of diabetes, involves excessive proliferation and inflammation of Muller cells and ultimately leads to vision loss and blindness. SRY-box transcription factor 9 (SOX9) has been reported to be highly expressed in Müller cells in light-induced retinal damage rats, but the functional role of SOX9 in DR remains unclear. To explore this issue, the DR rat model was successfully constructed via injection with streptozotocin (65 mg/kg) and the retinal thicknesses and blood glucose levels were evaluated. Müller cells were treated with 25 mmol/l glucose to create a cell model in vitro. The results indicated that SOX9 expression was significantly increased in DR rat retinas and in Müller cells stimulated with a high glucose (HG) concentration. HG treatment promoted the proliferation and migration capabilities of Müller cells, whereas SOX9 knockdown reversed those behaviors. Moreover, SOX9 knockdown provided protection against an HG-induced inflammatory response, as evidenced by reduced tumor necrosis factor-α, IL-1β, and IL-6 levels in serum and decreased NLRP3 inflammasome activation. Notably, SOX9 acted as a transcription factor that positively regulated thioredoxin-interacting protein (TXNIP), a positive regulator of Müller cells gliosis under HG conditions. A dual-luciferase assay demonstrated that SOX9 could enhance TXNIP expression at the transcriptional level through binding to the promoter of TXNIP. Moreover, TXNIP overexpression restored the effects caused by SOX9 silencing. In conclusion, these findings demonstrate that SOX9 may accelerate the progression of DR by promoting glial cell proliferation, metastasis, and inflammation, which involves the transcriptional regulation of TXNIP, providing new theoretical fundamentals for DR therapy.

Blue light pollution causes retinal damage and degeneration by inducing ferroptosis.

With the development of technology and electronic products, the problem of light pollution is becoming more and more serious. Blue light, the most energetic light in visible light, is the main culprit of teenage vision problems in the modern environment. As the tissue with the highest oxygen consumption, the retina is vulnerable to oxidative stress. However, the exact way in which blue light-triggered reactive oxygen species (ROS) cause retinal cell death remains unclear. Ferroptosis is a newly defined cell death pathway, whose core molecular mechanism is cell death caused by excessive lipid peroxidation. In this study, the results indicated that blue light-triggered ROS burst in retinal cells, in the meantime, intracellular Fe2+ levels were also significantly up-regulated. Further, deferoxamine (DFO) significantly improved blue light-triggered lipid peroxidation and cell death in ARPE-19 cells, and ferrostatin-1 (Fer-1) alleviated retinal oxidative stress and degeneration in rats. Furthermore, the GSH-GPX4 and FSP1-CoQ10-NADH systems served as key systems for cellular defense against ferroptosis, and interestingly, our results demonstrated that blue light triggered imbalance of the GSH-GPX4 and FSP1-CoQ10-NADH systems in retinal cells. Taken together, these pieces of evidence suggest that ferroptosis may be a crucial pathway for blue light-induced retinal damage and degeneration, which helps us to understand exactly why blue light pollution causes visual impairment in adolescents.

Choice of an experimental model and modeling method in the study of the pathogenesis and methods of treatment of age-related macular degeneration (review)

Background. Experimental modeling of various pathological processes in the organ of vision is an integral part of both fundamental and applied research. For a deeper understanding of the pathogenesis of age-related macular degeneration (AMD) and testing of new methods of its treatment, various experimental models of AMD in animals have been developed. However, at the stage of setting up the experiment, each researcher faces the difficult task of choosing an adequate animal model that has the closest homology with human anatomy and pathology, as well as a method for modeling it.Purpose. To analyze the literature data concerning the choice of AMD experimental model and methods for its modeling, to assess the advantages and limitations of their use in the study of the pathogenesis and effectiveness of modern methods for treating this ophthalmopathology.Materials and methods. The analysis of publications on PubMed, eLibrary, Cyberleninka resources for the period from 2000 year to the present has been carried out.Results. The review considers the criteria for selecting experimental models and groups of animals most often used as an object of study (mice, rats, rabbits, pigs and primates). Among the methods for AMD modeling, chemically induced methods (using sodium iodate, N-methyl-N-nitrosourea and cobalt chloride), as well as physically induced methods (mechanical and light damage to reti na) were analyzed.Conclusion. The use of rabbits as an object of study, even though the macular area is absent, is a well-established model of AMD, in view of the fact that the structure of their reti na corresponds to the general structure of the mammalian retina in areas of greatest visual acuity. Light-induced retinal damage occupies a leading position among AMD modeling methods, which is characterized by a number of advantages – control of the time and intensity of exposure to obtain the required degree of degeneration. The information presented in this review will allow researchers to choose the most adequate model among experimental animals and a method for modeling AMD.

Morphological and electrophysiological changes of retina after different light damage in three patients: Three case reports

Light-induced retinal damage is a serious vision-threatening disease, resulting from unsuitable laser irradiation, high-power light and sustaining light exposure. Therefore, effectively evaluate the morphological and functional of retinal damage is urgently needed. Now, we mainly reported three patients suffered from typical light irradiations. Patient 1 suffered from old laser pointer irradiation and followed with amblyopia treatment. Patient 2 suffered from acute high-energy light irradiation. Patient 3 suffered from sustaining optical fiber irradiation. Detailed morphological and functional examinations of the retina revealed that the lesions of the three patients had many similar characteristics, such as macular morphological changes, patent pattern visual monitoring amplitude or peak time abnormalities, multi-fucus electroretinograms macular central amplitude density decreased. In conclusion, light-induced retinopathy has many common features, which can help clinical medical staff to diagnose retinal photodamage diseases.

The novel visual cycle inhibitor (±)-RPE65-61 protects retinal photoreceptors from light-induced degeneration.

The visual cycle refers to a series of biochemical reactions of retinoids in ocular tissues and supports the vision in vertebrates. The visual cycle regenerates visual pigments chromophore, 11-cis-retinal, and eliminates its toxic byproducts from the retina, supporting visual function and retinal neuron survival. Unfortunately, during the visual cycle, when 11-cis-retinal is being regenerated in the retina, toxic byproducts, such as all-trans-retinal and bis-retinoid is N-retinylidene-N-retinylethanolamine (A2E), are produced, which are proposed to contribute to the pathogenesis of the dry form of age-related macular degeneration (AMD). The primary biochemical defect in Stargardt disease (STGD1) is the accelerated synthesis of cytotoxic lipofuscin bisretinoids, such as A2E, in the retinal pigment epithelium (RPE) due to mutations in the ABCA4 gene. To prevent all-trans-retinal—and bisretinoid-mediated retinal degeneration, slowing down the retinoid flow by modulating the visual cycle with a small molecule has been proposed as a therapeutic strategy. The present study describes RPE65-61, a novel, non-retinoid compound, as an inhibitor of RPE65 (a key enzyme in the visual cycle), intended to modulate the excessive activity of the visual cycle to protect the retina from harm degenerative diseases. Our data demonstrated that (±)-RPE65-61 selectively inhibited retinoid isomerase activity of RPE65, with an IC50 of 80 nM. Furthermore, (±)-RPE65-61 inhibited RPE65 via an uncompetitive mechanism. Systemic administration of (±)-RPE65-61 in mice resulted in slower chromophore regeneration after light bleach, confirming in vivo target engagement and visual cycle modulation. Concomitant protection of the mouse retina from high-intensity light damage was also observed. Furthermore, RPE65-61 down-regulated the cyclic GMP-AMP synthase stimulator of interferon genes (cGAS-STING) pathway, decreased the inflammatory factor, and attenuated retinal apoptosis caused by light-induced retinal damage (LIRD), which led to the preservation of the retinal function. Taken together, (±)-RPE65-61 is a potent visual cycle modulator that may provide a neuroprotective therapeutic benefit for patients with STGD and AMD.

UBE3D Is Involved in Blue Light-Induced Retinal Damage by Regulating Double-Strand Break Repair.

PurposeAge-related macular degeneration (AMD) is currently the leading cause of blindness worldwide. Previously, we identified ubiquitin-protein ligase E3D (UBE3D) as an AMD-associated protein for East Asian populations, and here we further demonstrate that UBE3D could be associated with DNA damage response.MethodsThe established I-SceI-inducible GFP reporter system was used to explore the effect of UBE3D on homologous recombination. Immunoprecipitation-mass spectrometry (MS) was used to explore potential UBE3D−interacting proteins and validated with coimmunoprecipitation assays and the pulldown assays. Micrococcal nuclease (MNase) assays were used to investigate the function of UBE3D on heterochromatin de-condensation upon DNA damage. An aged mouse model of blue light-induced eye damage was constructed, and electroretinography (ERG) and optical coherence tomography (OCT) were performed to compare the differences between wild-type and UBE3D+/− mice.ResultsFirst, we show that GFP-UBE3D is recruited to damage sites by PCNA, through a PCNA-interacting protein (PIP) box. Furthermore, UBE3D interacts with KAP1 via R377R378 and oxidation of the AMD-associated V379M mutation abolishes KAP1-UBE3D binding. By MNase assays, UBE3D depletion reduces the chromatin relaxation levels upon DNA damage. In addition, UBE3D depletion renders less KAP1 recruitment. Compared with wild type, blue light induces less damage in UBE3D+/− mice as measured by ERG and OCT, consistent with our biochemical results.ConclusionsHence, we propose that one potential mechanism that UBE3D-V379M contributes to AMD pathogenesis might be via defective DNA damage repair linked with oxidative stress and our results offered a potential direction for the treatment of AMD.

Profiles of Rho, Opn4, c-Fos, and Birc5 mRNA expression in Wistar rat retinas exposed to white or monochromatic light.

Despite concern over potential retinal damage linked to exposure to light-emitting-diode (LED) light (particularly blue light), it remains unknown how exposure to low-intensity monochromatic LED light affects the expression of rhodopsin (Rho, a photopigment that mediates light-induced retinal degeneration), melanopsin (Opn4, a blue-light sensitive photopigment), c-Fos (associated with retinal damage/degeneration), and Birc5 (anti-apoptotic). This study investigated the mRNA expression profiles of these genes under exposure to white and monochromatic light (blue, red, green) in the retinas of albino rats under a cycle of 12 h of light and 12 h of darkness. In each group, 32 Wistar rats were exposed to one type of monochromatic-LED or white-fluorescent light for 7 day (150 lx). Retinal samples were taken for qPCR analysis and light and electron microscopy. Blue and green light exposure markedly decreased expression of Rho and Opn4 mRNA and increased expression of Birc5 and c-Fos mRNA (P < 0.05). In retinas from the blue-light group, loss and vesiculation of photoreceptor outer segments were visible, but not in retinas from the red-light and control group. Measurements of the photoreceptor inner and outer segments length revealed, that this length was significantly decreased in the blue- and green-light exposure groups (P < 0.02), but not in the red-light exposure group. Increased expression of Birc5 and decreased expression of Rho and Opn4 after exposure to blue and green light may be early responses that help to reduce light-induced retinal damage.

Protective effects of Panax ginseng berry extract on blue light-induced retinal damage in ARPE-19 cells and mouse retina

BackgroundAge-related macular degeneration (AMD) is a significant visual disease that induces impaired vision and irreversible blindness in the elderly. However, the effects of ginseng berry extract (GBE) on the retina have not been studied. Therefore, this study aimed to investigate the protective effects of GBE on blue light (BL)-induced retinal damage and elucidate its underlying mechanisms in human retinal pigment epithelial cells (ARPE-19 cells) and Balb/c retina. MethodsTo investigate the effects and underlying mechanisms of GBE on retinal damage in vitro, we performed cell viability assay, pre-and post-treatment of sample, reactive oxygen species (ROS) assay, quantitative real-time PCR (qRT-PCR), and western immunoblotting using A2E-laden ARPE-19 cells with BL exposure. In addition, Balb/c mice were irradiated with BL to induce retinal degeneration and orally administrated with GBE (50, 100, 200 mg/kg). Using the harvested retina, we performed histological analysis (thickness of retinal layers), qRT-PCR, and western immunoblotting to elucidate the effects and mechanisms of GBE against retinal damage in vivo. ResultsGBE significantly inhibited BL-induced cell damage in ARPE-19 cells by activating the SIRT1/PGC-1α pathway, regulating NF-kB translocation, caspase 3 activation, PARP cleavage, expressions of apoptosis-related factors (BAX/BCL-2, LC3-Ⅱ, and p62), and ROS production. Furthermore, GBE prevented BL-induced retinal degeneration by restoring the thickness of retinal layers and suppressed inflammation and apoptosis via regulation of NF-kB and SIRT1/PGC-1α pathway, cleavage of caspase 3 and PARP, and expressions of apoptosis-related factors in vivo. ConclusionsGBE could be a potential agent to prevent dry AMD and progression to wet AMD.