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Absence of Sigma 1 Receptor Accelerates Photoreceptor Cell Death in a Murine Model of Retinitis Pigmentosa
摘要： Sigma 1 Receptor (Sig1R) is a novel therapeutic target in neurodegenerative diseases, including retinal disease. Sig1R(cid:2)/(cid:2) mice have late-onset retinal degeneration with ganglion cell loss that worsens under stress. Whether Sig1R plays a role in maintaining other retinal neurons is unknown, but was investigated here using rd10 mice, a model of severe photoreceptor degeneration. METHODS. Wild-type, rd10, and rd10/Sig1R(cid:2)/(cid:2) mice were subjected to ERG and spectral-domain optical coherence tomography (SD-OCT) to assess visual function/structure in situ. Retinas imaged microscopically were subjected to morphometric analysis, immunodetection of cones, and analysis of gliosis. Oxidative and endoplasmic reticulum (ER) stress was evaluated at mRNA/protein levels. RESULTS. Photopic ERG responses were reduced signi?cantly in rd10/Sig1R(cid:2)/(cid:2) versus rd10 mice at P28 (31 6 6 vs. 56 6 7 lV), indicating accelerated cone loss when Sig1R was absent. At P28, SD-OCT revealed reduced retinal thickness in rd10/Sig1R(cid:2)/(cid:2) mice (60% of WT) versus rd10 (80% of WT). Morphometric analysis disclosed profound photoreceptor nuclei loss in rd10/Sig1R(cid:2)/(cid:2) versus rd10 mice. rd10/Sig1R(cid:2)/(cid:2) mice had 35% and 60% fewer photoreceptors, respectively, at P28 and P35, than rd10. Peanut agglutinin cone labeling decreased signi?cantly; gliosis increased signi?cantly in rd10/Sig1R(cid:2)/(cid:2) versus rd10 mice. At P21, NRF2 levels increased in rd10/Sig1R(cid:2)/(cid:2) mice versus rd10 and downstream antioxidants increased indicating oxidative stress. At P28, ER stress genes/proteins, especially XBP1, a potent transcriptional activator of the unfolded protein response and CHOP, a proapoptotic transcription factor, increased signi?cantly in rd10/Sig1R(cid:2)/(cid:2) mice versus rd10. CONCLUSIONS. Photoreceptor cell degeneration accelerates and cone function diminishes much earlier in rd10/Sig1R(cid:2)/(cid:2) than rd10 mice emphasizing the importance of Sig1R as a modulator of retinal cell survival.
关键词： cones,retinal neuroprotection,rods,retinal degeneration,rd10 mouse,ERG
更新于2025-09-19 17:15:36
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Maintenance of Rhodopsin levels in <i>Drosophila</i> photoreceptor and phototransduction requires Protein Kinase D
摘要： During Drosophila phototransduction, the G protein coupled receptor (GPCR) Rhodopsin (Rh1) transduces photon absorption into electrical signal via G-protein coupled activation of phospholipase C (PLC). Rh1 levels in the plasma membrane are critical for normal sensitivity to light. In this study, we report that Protein kinase D (dPKD) regulates Rh1 homeostasis in adult photoreceptors. Although eye development and retinal structure are unaffected in the dPKD hypomorph (dPKDH), it exhibited elevated levels of Rh1. Surprisingly, despite having elevated levels of Rh1, no defect was observed in the electrical response to light in these flies. By contrast the levels of another transmembrane protein of the photoreceptor plasma membrane, Transient receptor potential (TRP) was not altered in dPKDH. Our results indicate that dPKD is dispensable for eye development but is required for maintaining Rh1 levels in adult photoreceptors.
关键词： Electroretinogram (ERG),Phototransduction,Retinal degeneration,Rhodopsin,Drosophila,Rhodopsin loaded vesicle (RLVs),Protein Kinase D
更新于2025-09-19 17:15:36
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Molecular Diagnosis of Inherited Retinal Diseases in Indigenous African Populations by Whole-Exome Sequencing
摘要： PURPOSE. A majority of genes associated with inherited retinal diseases (IRDs) have been identi?ed in patients of European origin. Indigenous African populations exhibit rich genomic diversity, and evaluation of reported genetic mutations has yielded low returns so far. Our goal was to perform whole-exome sequencing (WES) to examine variants in known IRD genes in underrepresented African cohorts. METHODS. Whole-exome sequencing was performed on 56 samples from 16 families with diverse IRD phenotypes that had remained undiagnosed after screening for known mutations using genotyping-based microarrays (Asper Ophthalmics). Variants in reported IRD genes were identi?ed using WES and validated by Sanger sequencing. Custom TaqMan assays were used to screen for identi?ed mutations in 193 unrelated indigenous Africans with IRDs. RESULTS. A total of 3494 variants were identi?ed in 217 known IRD genes, leading to the identi?cation of seven different mutations (including six novel) in six genes (RHO, PRPF3, PRPF31, ABCA4, CERKL, and PDE6B) in six distinct families. TaqMan screening in additional probands revealed identical homozygous CERKL and PDE6B variants in four more patients. CONCLUSIONS. This is the ?rst report of WES of patients with IRDs in indigenous African populations. Our study identi?ed genetic defects in almost 40% of the families analyzed, signi?cantly enhancing the molecular diagnosis of IRD in South Africa. Thus, WES of understudied cohorts seems to present an effective strategy for determining novel mutations in heterogeneous retinal diseases.
关键词： genetic testing,vision loss,inherited blindness,South Africa,retinal degeneration,next generation sequencing,photoreceptor dysfunction,clinical genetics
更新于2025-09-11 14:15:04
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Photobiomodulation for the treatment of retinal diseases: a review
摘要： Photobiomodulation (PBM), also known as low level laser therapy, has recently risen to the attention of the ophthalmology community as a promising new approach to treat a variety of retinal conditions including age-related macular degeneration, retinopathy of prematurity, diabetic retinopathy, Leber's hereditary optic neuropathy, amblyopia, methanol-induced retinal damage, and possibly others. This review evaluates the existing research pertaining to PBM applications in the retina, with a focus on the mechanisms of action and clinical outcomes. All available literature until April 2015 was reviewed using PubMed and the following keywords: 'photobiomodulation AND retina', 'low level light therapy AND retina', 'low level laser therapy AND retina', and 'FR/NIR therapy AND retina'. In addition, the relevant references listed within the papers identified through PubMed were incorporated. The literature supports the conclusion that the low-cost and non-invasive nature of PBM, coupled with the first promising clinical reports and the numerous preclinical-studies in animal models, make PBM well-poised to become an important player in the treatment of a wide range of retinal disorders. Nevertheless, large-scale clinical trials will be necessary to establish the PBM therapeutic ranges for the various retinal diseases, as well as to gain a deeper understanding of its mechanisms of action.
关键词： low level laser therapy,age-related macular degeneration,retinopathy of prematurity,photobiomodulation,retinal degeneration,amblyopia,far-red to near-infrared,methanol toxicity,retinitis pigmentosa
更新于2025-09-10 09:29:36
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Repeatability of Cone Spacing Measures in Eyes With Inherited Retinal Degenerations
摘要： PURPOSE. To determine short-term variability of adaptive optics scanning laser ophthalmoscopy (AOSLO)–derived cone spacing measures in eyes with inherited retinal degenerations (IRD) and in normal eyes. METHODS. Twenty IRD patients and 10 visually normal subjects underwent AOSLO imaging at two visits separated by no more than 1 month (NCT00254605). Cone spacing was measured in multiple macular regions in each image by three independent graders. Variability of cone spacing measures between visits, between graders, and between eyes was determined and correlated with standard clinical measures. RESULTS. Cone spacing was measured in 2905 regions. Interobserver agreement was high both in normal eyes and eyes with IRD (mean intraclass correlation coef?cient [ICC] ? 0.838 for normal and 0.892 for eyes with IRD). Cone spacing measures were closely correlated between visits (ICC > 0.869 for both study groups). Mean relative intervisit spacing difference (absolute difference in measures divided by the mean at each region) was 4.0% for normal eyes and 4.9% for eyes with IRD. Cone spacing measures from fellow eyes of the same subject showed strong agreement for all subjects (ICC > 0.85 for both study groups). CONCLUSIONS. Adaptive optics scanning laser ophthalmoscopy–derived macular cone spacing measures were correlated between observers, visits, and fellow eyes of the same subject in normal eyes and in eyes with IRD. This information may help establish the role of cone spacing measures derived from images of the cone mosaic obtained with AOSLO as a sensitive biomarker for longitudinal tracking of photoreceptor loss during disease progression and in response to treatment. (ClinicalTrials.gov number, NCT00254605.)
关键词： retinal,adaptive optics,photoreceptor,imaging,retinitis pigmentosa,retinal degeneration
更新于2025-09-10 09:29:36
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ADP-Ribosylation Factor-Like 2 (ARL2) regulates cilia stability and development of outer segments in rod photoreceptor neurons
摘要： Photoreceptor cells are specialized neurons with a sensory cilium carrying an elaborate membrane structure, the outer segment (OS). Inherited mutations in genes involved in ciliogenesis frequently result in OS malformation and blindness. ADP-ribosylation factor-like 2 (ARL2) has recently been implicated in OS formation through its association with Binder of ARL2 (BART or ARL2BP), a protein linked to inherited blinding disease. To test the role of ARL2 in vision we created a transgenic mouse model expressing a tagged-dominant active form of human ARL2 (ARL2-Q70L) under a rod-specific promoter. Transgenic ARL2-Q70L animals exhibit reduced photoreceptor cell function as early as post-natal day 16 and progressive rod degeneration. We attribute loss of photoreceptor function to the defective OS morphogenesis in the ARL2-Q70L transgenic model. ARL2-Q70L expression results in shortened inner and outer segments, shortened and mislocalized axonemes and cytoplasmic accumulation of rhodopsin. In conclusion, we show that ARL2-Q70L is crucial for photoreceptor neuron sensory cilium development. Future research will expand upon our hypothesis that ARL2-Q70L mutant interferes with microtubule maintenance and tubulin regulation resulting in impaired growth of the axoneme and elaboration of the photoreceptor outer segment.
关键词： cilia,outer segment,ARL2,photoreceptor,retinal degeneration,ADP-ribosylation factor-like 2
更新于2025-09-10 09:29:36
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Sarpogrelate, a 5-HT <sub/>2A</sub> Receptor Antagonist, Protects the Retina From Light-Induced Retinopathy
摘要： PURPOSE. To determine if sarpogrelate, a selective 5-HT2A receptor antagonist, is protective against light-induced retinopathy in BALB/c mice. METHODS. BALB/c mice were dosed intraperitoneally with 5, 15, 30, 40, or 50 mg/kg sarpogrelate 48, 24, and 0 hours prior to bright light exposure (10,000 lux) as well as 24 and 48 hours after exposure. Additionally, a single injection regimen was evaluated by injecting mice with 50 mg/kg sarpogrelate once immediately prior to light exposure. To investigate the potential for additive effects of serotonin receptor agents, a combination therapy consisting of sarpogrelate (15 mg/kg) and 8-OH-DPAT (1 mg/kg) was evaluated with the 5-day treatment regimen. Neuroprotection was characterized by the preservation of retinal thickness and function, measured by spectral-domain optical coherence tomography (SD-OCT) and electroretinography (ERG), respectively. RESULTS. Mice that were light damaged and injected with saline had significantly reduced outer retinal thickness, total retinal thickness, and ERG amplitudes compared with na?ve mice. A 5-day administration of 15, 30, or 40 mg/kg of sarpogrelate was able to partially protect retinal morphology and full protection of retinal morphology was achieved with a 50 mg/kg dose. Both 15 and 30 mg/kg doses of sarpogrelate partially preserved retinal function measured by ERG, whereas 40 and 50 mg/kg doses fully preserved retinal function. Additionally, a single administration of 50 mg/kg sarpogrelate was able to fully preserve both retinal morphology and function. Administration of 15 mg/kg of sarpogrelate and 1 mg/kg of 8-OH-DPAT together demonstrated an additive effect and fully preserved retinal morphology. CONCLUSIONS. A 5- or 1-day treatment with 50 mg/kg sarpogrelate can completely protect the retina of BALB/c mice from light-induced retinopathy. Partial protection can be achieved with lower doses starting at 15 mg/kg and protection increases in a dose-dependent manner. Treatment with low doses of sarpogrelate and 8-OH-DPAT elicits an additive effect that results in full protection of retinal morphology.
关键词： MCI-9042,serotonin,neuroprotection,HT2A receptor,light-induced retinopathy,5-,retinal degeneration,sarpogrelate,Anplag
更新于2025-09-09 09:28:46
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Synthesized glucocorticoid-induced leucine zipper peptide (GILZ-P) inhibits photoreceptor apoptosis and protects retinal function in light-induced retinal degeneration model
摘要： Background: This study aimed to investigate the neuroprotective function of a synthesized glucocorticoid-induced leucine zipper peptide (GILZ-p) in a light-induced retinal degeneration model. Methods: The GILZ98–134 peptide was synthesized and injected intravitreally into Sprague Dawley rats. Retinal injury was then induced in the rats by exposing their eyes to constant white light (5000 lux) for 24 h. The activation of retinal caspases-9/3 and the release of cytochrome c from the mitochondria to the cytosol were measured at 1, 3, 5 and 7 days after light injury. Photoreceptor apoptosis was evaluated with TUNEL staining at 3 days after injury. Hematoxylin and eosin staining and electroretinography were used to observe the changes in the retinal morphology and function, respectively, 7 and 14 days after light injury. Results: The intravitreally injected synthesized GILZ-p successfully penetrated to the retina and significantly inhibited the activation of retinal caspase-3 and caspase-9 at 1, 3, 5, and 7 days after light injury, and reduced the number of TUNEL-positive photoreceptors at 3 days after light injury. GILZ-p pretreatment also alleviated cytochrome c release and rescued mitochondria-mediated apoptosis after injury. Simultaneously, GILP-p pretreatment also mitigated the light-induced thinning of the outer nuclear layer and the loss of retinal function at 7 and 14 days after light injury, respectively. Conclusion: The synthesized GILZ-p prevented light-induced photoreceptor apoptosis and protected retinal function from degeneration, and is therefore a potential therapeutic option for degenerative retinal diseases.
关键词： photoreceptor,retinal degeneration,synthesized peptide,apoptosis,GILZ
更新于2025-09-09 09:28:46
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Mouse Idh3a mutations cause retinal degeneration and reduced mitochondrial function
摘要： Isocitrate dehydrogenase (IDH) is an enzyme required for the production of α-ketoglutarate from isocitrate. IDH3 generates the NADH used in the mitochondria for ATP production, and is a tetramer made up of two α, a β and a γ subunit. Loss of function and missense mutations in both IDH3A andIDH3B have previously been implicated in families exhibiting retinal degeneration. Using mouse models we have investigated the role of IDH3 in retinal disease and mitochondrial function. We identified mice with late-onset retinal degeneration in a screen of ageing mice carrying an ENU-induced mutation, E229K, in Idh3a. Mice homozygous for this mutation exhibit signs of retinal stress, indicated by GFAP staining, as early as 3 months, but no other tissues appear to be affected. We produced a knockout of Idh3a and found that homozygous mice do not survive past early embryogenesis. Idh3a-/E229K compound heterozygous mutants exhibit a more severe retinal degeneration when compared to Idh3aE229K/E229K. Analysis of mitochondrial function in mutant cell lines highlighted a reduction in mitochondrial maximal respiration and reserve capacity levels in both Idh3aE229K/E229K and Idh3a-/E229K cells. Loss-of function Idh3b mutants do not exhibit the same retinal degeneration phenotype, with no signs of retinal stress or reduction in mitochondrial respiration. It has been previously reported that the retina operates with a limited mitochondrial reserve capacity and we suggest that this, in combination with the reduced reserve capacity in mutants, explains the degenerative phenotype observed in Idh3a mutant mice.
关键词： Isocitrate dehydrogenase,retinal degeneration,mouse models,mitochondrial function,IDH3
更新于2025-09-09 09:28:46
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Immunomodulation with minocycline rescues retinal degeneration in juvenile neuronal ceroid lipofuscinosis mice highly susceptible to light damage
摘要： Juvenile neuronal ceroid lipofuscinosis ( jNCL) is a rare but fatal inherited lysosomal storage disorder mainly affecting children. The disease is caused by mutations in the CLN3 gene that lead to the accumulation of storage material in many tissues, prominent immune responses and neuronal degeneration. One of the first symptoms is vision loss followed by motor dysfunction and mental decline. The established Cln3Δex7/8 mouse model mimics many pathological features of the human disease except the retinal phenotype, which is very mild and occurs only very late in these mice. Here, we first carefully analyzed the retinal structure and microglia responses in these animals. While prominent autofluorescent spots were present in the fundus, only a moderate reduction of retinal thickness and no prominent microgliosis was seen in young CLN3-deficient mice. We next genetically introduced a light-sensitive RPE65 variant and established a light-damage paradigm that showed a high susceptibility of young Cln3Δex7/8 mice after exposure to 10,000 lux bright light for 30 min. Under these ‘low light’ conditions, CLN3-deficient mice showed a strong retinal degeneration, microglial activation, deposition of autofluorescent material and transcriptomic changes compared to wild-type animals. Finally, we treated the light-exposed Cln3Δex7/8 animals with the immunomodulatory compound minocycline, and thereby rescued the retinal phenotype and diminished microgliosis. Our findings indicate that exposure to specific light conditions accelerates CLN3-dependent retinal degeneration, and that immunomodulation by minocycline could be a possible treatment option to delay vision loss in jNCL patients.
关键词： CLN3,Minocycline,Retinal degeneration,Microglia,Juvenile neuronal ceroid lipofuscinosis
更新于2025-09-09 09:28:46