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International Journal of Molecular... Nov 2022Diabetic retinopathy (DR) was identified as a leading cause of blindness and vision impairment in 2020. In addition to vasculopathy, DR has been found to involve retinal...
Diabetic retinopathy (DR) was identified as a leading cause of blindness and vision impairment in 2020. In addition to vasculopathy, DR has been found to involve retinal neurons, including amacrine cells and retinal ganglion cells. Despite possessing features that are susceptible to diabetic conditions, photoreceptor cells have received relatively little attention with respect to the development of DR. Until recently, studies have suggested that photoreceptors secret proinflammatory molecules and produce reactive oxygen species that contribute to the development of DR. However, the effect of hyperglycemia on photoreceptors and its underlying mechanism remains elusive. In this study, the direct effect of high glucose on photoreceptor cells was investigated using a 661w photoreceptor-like cell line. A data-independent sequential window acquisition of all theoretical mass spectra (SWATH)-based proteomic approach was employed to study changes induced by high glucose in the proteomic profile of the cells. The results indicated that high glucose induced a significant increase in apoptosis and ROS levels in the 661w cells, with mitochondrial dysfunction among the major affected canonical pathways. The involvement of mitochondrial dysfunction was further supported by increased mitochondrial fission and reduced mitochondrial bioenergetics. Collectively, these findings provide a biological basis for a possible role of photoreceptors in the pathogenesis of DR.
Topics: Humans; Proteomics; Hyperglycemia; Photoreceptor Cells; Diabetic Retinopathy; Mitochondria; Glucose
PubMed: 36362154
DOI: 10.3390/ijms232113366 -
Aging Oct 2019Previous studies have shown that PCB has an adverse effect on zebrafish retinal development, but the basic mechanism behind it is not clear. The purpose of this study...
Previous studies have shown that PCB has an adverse effect on zebrafish retinal development, but the basic mechanism behind it is not clear. The purpose of this study was to investigate the molecular mechanisms of PCB-induced retinal dysplasia. RT-qPCR, immunoblotting, HE staining and immunofluorescence were adopted to detect the expression at mRNA and protein level. Functional experiments were carried out in 661w cells including CCK-8 assay, caspase-3 assay, and the flow cytometry, while the functional role of miR - 20b was further investigated by using the zebrafish model. The result showed that PCB exposure inhibited cell proliferation and increased the apoptosis of the 661w cells, and the dose-response relationship between the retinal development-related genes (SWS1, CRX, Rho), miR-20b expression and PCB exposure was also discovered. We confirmed that miR-20b targeted FGF2 and GRB2 by constructing a dual luciferase reporter gene and suppressed the cell function as well as PCB. In the miR-20b overexpression zebrafish model, we found abnormal retinal morphology characterized by sparse and irregular photoreceptor cells and the thick photoreceptor cell layers. Our results demonstrate for the first time that PCBs target the MAPK/ERK signaling through miR-20b, affecting retinal cell development and leading to visual impairment.
Topics: Animals; Apoptosis; Cell Differentiation; Cell Line; Cell Proliferation; Gene Expression Regulation; MicroRNAs; Photoreceptor Cells, Vertebrate; Polychlorinated Biphenyls; Rats; Retina; Zebrafish
PubMed: 31619580
DOI: 10.18632/aging.102360 -
Molecules (Basel, Switzerland) Aug 2023Rods and cones are the photoreceptor cells containing the visual pigment proteins that initiate visual phototransduction following the absorption of a photon. Photon... (Review)
Review
Rods and cones are the photoreceptor cells containing the visual pigment proteins that initiate visual phototransduction following the absorption of a photon. Photon absorption induces the photochemical transformation of a visual pigment, which results in the sequential formation of distinct photo-intermediate species on the femtosecond to millisecond timescales, whereupon a visual electrical signal is generated and transmitted to the brain. Time-resolved spectroscopic studies of the rod and cone photo-intermediaries enable the detailed understanding of initial events in vision, namely the key differences that underlie the functionally distinct scotopic (rod) and photopic (cone) visual systems. In this paper, we review our recent ultrafast (picoseconds to milliseconds) transient absorption studies of rod and cone visual pigments with a detailed comparison of the transient molecular spectra and kinetics of their respective photo-intermediaries. Key results include the characterization of the porphyropsin (carp fish rhodopsin) and human green-cone opsin photobleaching sequences, which show significant spectral and kinetic differences when compared against that of bovine rhodopsin. These results altogether reveal a rather strong interplay between the visual pigment structure and its corresponding photobleaching sequence, and relevant outstanding questions that will be further investigated through a forthcoming study of the human blue-cone visual pigment are discussed.
Topics: Animals; Cattle; Humans; Rhodopsin; Kinetics; Retinal Cone Photoreceptor Cells; Vision, Ocular
PubMed: 37570798
DOI: 10.3390/molecules28155829 -
Stem Cell Research & Therapy Aug 2021Retinal regenerative therapies hold great promise for the treatment of inherited retinal degenerations (IRDs). Studies in preclinical lower mammal models of IRDs have...
BACKGROUND
Retinal regenerative therapies hold great promise for the treatment of inherited retinal degenerations (IRDs). Studies in preclinical lower mammal models of IRDs have suggested visual improvement following retinal photoreceptor precursors transplantation, but there is limited evidence on the ability of these transplants to rescue retinal damage in higher mammals. The purpose of this study was to evaluate the therapeutic potential of photoreceptor precursors derived from clinically compliant induced pluripotent stem cells (iPSCs).
METHODS
Photoreceptor precursors were sub-retinally transplanted into non-human primates (Macaca fascicularis). The cells were transplanted both in naïve and cobalt chloride-induced retinal degeneration models who had been receiving systemic immunosuppression for one week prior to the procedure. Optical coherence tomography, fundus autofluorescence imaging, electroretinography, ex vivo histology and immunofluorescence staining were used to evaluate retinal structure, function and survival of transplanted cells.
RESULTS
There were no adverse effects of iPSC-derived photoreceptor precursors on retinal structure or function in naïve NHP models, indicating good biocompatibility. In addition, photoreceptor precursors injected into cobalt chloride-induced retinal degeneration NHP models demonstrated an ability both to survive and to mature into cone photoreceptors at 3 months post-transplant. Optical coherence tomography showed restoration of retinal ellipsoid zone post-transplantation.
CONCLUSIONS
These findings demonstrate the safety and therapeutic potential of clinically compliant iPSC-derived photoreceptor precursors as a cell replacement source for future clinical trials.
Topics: Animals; Humans; Induced Pluripotent Stem Cells; Photoreceptor Cells, Vertebrate; Primates; Retinal Cone Photoreceptor Cells; Retinal Degeneration
PubMed: 34412697
DOI: 10.1186/s13287-021-02539-8 -
Proceedings of the National Academy of... Jun 2023Retinitis pigmentosa (RP) is an ocular disease characterized by the loss of night vision, followed by the loss of daylight vision. Daylight vision is initiated in the...
Retinitis pigmentosa (RP) is an ocular disease characterized by the loss of night vision, followed by the loss of daylight vision. Daylight vision is initiated in the retina by cone photoreceptors, which are gradually lost in RP, often as bystanders in a disease process that initiates in their neighboring rod photoreceptors. Using physiological assays, we investigated the timing of cone electroretinogram (ERG) decline in RP mouse models. A correlation between the time of loss of the cone ERG and the loss of rods was found. To investigate a potential role of the visual chromophore supply in this loss, mouse mutants with alterations in the regeneration of the retinal chromophore, 11- retinal, were examined. Reducing chromophore supply via mutations in or resulted in greater cone function and survival in a RP mouse model. Conversely, overexpression of and , genes that can drive the regeneration of the chromophore, led to greater cone degeneration. These data suggest that abnormally high chromophore supply to cones upon the loss of rods is toxic to cones, and that a potential therapy in at least some forms of RP is to slow the turnover and/or reduce the level of visual chromophore in the retina.
Topics: Mice; Animals; Retina; Retinal Cone Photoreceptor Cells; Retinal Rod Photoreceptor Cells; Retinitis Pigmentosa; Color Vision; Disease Models, Animal
PubMed: 37252956
DOI: 10.1073/pnas.2217885120 -
Investigative Ophthalmology & Visual... Apr 2020Analysis of photoreceptor morphology and gene expression in mispatterned eyes of zebrafish growth differentiation factor 6a (gdf6a) mutants.
PURPOSE
Analysis of photoreceptor morphology and gene expression in mispatterned eyes of zebrafish growth differentiation factor 6a (gdf6a) mutants.
METHODS
Rod and cone photoreceptors were compared between gdf6a mutant and control zebrafish from larval to late adult stages using transgenic labels, immunofluorescence, and confocal microscopy, as well as by transmission electron microscopy. To compare transcriptomes between larval gdf6a mutant and control zebrafish, RNA-Seq was performed on isolated eyes.
RESULTS
Although rod and cone photoreceptors differentiate in gdf6a mutant zebrafish, the cells display aberrant growth and morphology. The cone outer segments, the light-detecting sensory endings, are reduced in size in the mutant larvae and fail to recover to control size at subsequent stages. In contrast, rods form temporarily expanded outer segments. The inner segments, which generate the required energy and proteins for the outer segments, are shortened in both rods and cones at all stages. RNA-Seq analysis provides a set of misregulated genes associated with the observed abnormal photoreceptor morphogenesis.
CONCLUSIONS
GDF6 mutations were previously identified in patients with Leber congenital amaurosis. Here, we reveal a unique photoreceptor phenotype in the gdf6a mutant zebrafish whereby rods and cones undergo abnormal maturation distinct for each cell type. Further, subsequent development shows partial recovery of cell morphology and maintenance of the photoreceptor layer. By conducting a transcriptomic analysis of the gdf6a larval eyes, we identified a collection of genes that are candidate regulators of photoreceptor size and morphology.
Topics: Animals; Fluorescent Antibody Technique; Gene Expression Regulation, Developmental; Growth Differentiation Factor 6; In Situ Hybridization; Larva; Microscopy, Confocal; Microscopy, Electron, Transmission; Morphogenesis; Mutation; Paraffin Embedding; Real-Time Polymerase Chain Reaction; Retinal Cone Photoreceptor Cells; Retinal Rod Photoreceptor Cells; Zebrafish; Zebrafish Proteins
PubMed: 32293666
DOI: 10.1167/iovs.61.4.9 -
Cells Sep 2020Photoreceptor disease results in irreparable vision loss and blindness, which has a dramatic impact on quality of life. Pathogenic mutations in lead to photoreceptor...
Photoreceptor disease results in irreparable vision loss and blindness, which has a dramatic impact on quality of life. Pathogenic mutations in lead to photoreceptor degenerations such as occult macular dystrophy and retinitis pigmentosa. RP1L1 is a component of the photoreceptor axoneme, the backbone structure of the photoreceptor's light-sensing outer segment. We generated an zebrafish mutant using CRISPR/Cas9 genome editing. Mutant animals had progressive photoreceptor functional defects as determined by electrophysiological assessment. Optical coherence tomography showed gaps in the photoreceptor layer, disrupted photoreceptor mosaics, and thinner retinas. Mutant retinas had disorganized photoreceptor outer segments and lipid-rich subretinal drusenoid deposits between the photoreceptors and retinal pigment epithelium. Our mutant is a novel model of -associated photoreceptor disease and the first zebrafish model of photoreceptor degeneration with reported subretinal drusenoid deposits, a feature of age-related macular degeneration.
Topics: Animals; Macular Degeneration; Male; Photoreceptor Cells, Vertebrate; Zebrafish
PubMed: 33007938
DOI: 10.3390/cells9102214 -
The International Journal of... 2021Photoreceptor cells of the vertebrate neural retina originate in the neuroepithelium, and like other neurons, must undergo cell body translocation and polarity...
Photoreceptor cells of the vertebrate neural retina originate in the neuroepithelium, and like other neurons, must undergo cell body translocation and polarity transitions to acquire their final functional morphology, which includes features of neuronal and epithelial cells. We analyzed this process in detail in zebrafish embryos using confocal microscopy and electron microscopy. Photoreceptor progenitors were labeled by the transgenic expression of enhanced green fluorescent protein under the regulation of the photoreceptor-specific promoter , and structures of interest were disrupted using morpholino oligomers to knock-down specific genes. Photoreceptor progenitors detached from the basal retina at pre-mitotic stages, rapidly retracting a short basal process as the cell body translocated apically. They remained at an apical position indefinitely to form the outer nuclear layer (ONL), initially extending and retracting highly dynamic neurite-like processes, tangential to the apical surface. Many photoreceptor progenitors presented a short apical primary cilium. The number and length of these cilia was gradually reduced until nearly disappearing around 60 hpf. Their disruption by knocking-down and caused a notorious defect on basal process retraction. To assess the role of cell adhesion in the organization of photoreceptor progenitors, we knocked-down /N-cadherin and observed the cell behavior by time-lapse microscopy. The ectopic photoreceptor progenitors initially migrated in an apparent random manner, profusely extending cell processes, until they encountered other cells to establish cell rosettes in which they stayed, acquiring photoreceptor-like polarity. Altogether, our observations indicate a complex regulation of photoreceptor progenitor dynamics to form the retinal ONL, previous to the post-mitotic maturation stages.
Topics: Animals; Cadherins; Cilia; Photoreceptor Cells; Retina; Zebrafish
PubMed: 32930348
DOI: 10.1387/ijdb.200113fz -
JCI Insight Jan 2022BACKGROUNDOutcome measures sensitive to disease progression are needed for ATP-binding cassette, sub-family A, member 4-associated (ABCA4-associated) retinopathy. We... (Observational Study)
Observational Study
BACKGROUNDOutcome measures sensitive to disease progression are needed for ATP-binding cassette, sub-family A, member 4-associated (ABCA4-associated) retinopathy. We aimed to quantify ellipsoid zone (EZ) loss and photoreceptor degeneration beyond EZ-loss in ABCA4-associated retinopathy and investigate associations between photoreceptor degeneration, genotype, and age.METHODSWe analyzed 132 eyes from 66 patients (of 67 enrolled) with molecularly confirmed ABCA4-associated retinopathy from a prospective natural history study with a median [IQR] follow-up of 4.2 years [3.1, 5.1]. Longitudinal spectral-domain optical coherence tomography volume scans (37 B-scans, 30° × 15°) were segmented using a deep learning (DL) approach. For genotype-phenotype analysis, a model of ABCA4 variants was applied with the age of criterion EZ-loss (6.25 mm2) as the dependent variable.RESULTSPatients exhibited an average (square-root-transformed) EZ-loss progression rate of [95% CI] 0.09 mm/y [0.06, 0.11]. Outer nuclear layer (ONL) thinning extended beyond the area of EZ-loss. The average distance from the EZ-loss boundary to normalization of ONL thickness (to ±2 z score units) was 3.20° [2.53, 3.87]. Inner segment (IS) and outer segment (OS) thinning was less pronounced, with an average distance from the EZ-loss boundary to layer thickness normalization of 1.20° [0.91, 1.48] for the IS and 0.60° [0.49, 0.72] for the OS. An additive model of allele severity explained 52.7% of variability in the age of criterion EZ-loss.CONCLUSIONPatients with ABCA4-associated retinopathy exhibited significant alterations of photoreceptors outside of EZ-loss. DL-based analysis of photoreceptor laminae may help monitor disease progression and estimate the severity of ABCA4 variants.TRIAL REGISTRATIONClinicalTrials.gov identifier: NCT01736293.FUNDINGNational Eye Institute Intramural Research Program and German Research Foundation grant PF950/1-1.
Topics: ATP-Binding Cassette Transporters; Age Factors; Deep Learning; Disease Progression; Electroretinography; Female; Follow-Up Studies; Genetic Association Studies; Humans; Male; Middle Aged; Photoreceptor Cells, Vertebrate; Retina; Retinal Degeneration; Rod Cell Outer Segment; Severity of Illness Index; Tomography, Optical Coherence
PubMed: 35076026
DOI: 10.1172/jci.insight.155373 -
PLoS Genetics Sep 2023In the vertebrate eye, Notch ligands, receptors, and ternary complex components determine the destiny of retinal progenitor cells in part by regulating Hes effector gene...
In the vertebrate eye, Notch ligands, receptors, and ternary complex components determine the destiny of retinal progenitor cells in part by regulating Hes effector gene activity. There are multiple paralogues for nearly every node in this pathway, which results in numerous instances of redundancy and compensation during development. To dissect such complexity at the earliest stages of eye development, we used seven germline or conditional mutant mice and two spatiotemporally distinct Cre drivers. We perturbed the Notch ternary complex and multiple Hes genes to understand if Notch regulates optic stalk/nerve head development; and to test intracellular pathway components for their Notch-dependent versus -independent roles during retinal ganglion cell and cone photoreceptor competence and fate acquisition. We confirmed that disrupting Notch signaling universally blocks progenitor cell growth, but delineated specific pathway components that can act independently, such as sustained Hes1 expression in the optic stalk/nerve head. In retinal progenitor cells, we found that among the genes tested, they do not uniformly suppress retinal ganglion cell or cone differentiation; which is not due differences in developmental timing. We discovered that shifts in the earliest cell fates correlate with expression changes for the early photoreceptor factor Otx2, but not with Atoh7, a factor required for retinal ganglion cell formation. During photoreceptor genesis we also better defined multiple and simultaneous activities for Rbpj and Hes1 and identify redundant activities that occur downstream of Notch. Given its unique roles at the retina-optic stalk boundary and cone photoreceptor genesis, our data suggest Hes1 as a hub where Notch-dependent and -independent inputs converge.
Topics: Animals; Mice; Retina; Embryonic Development; Retinal Ganglion Cells; Retinal Cone Photoreceptor Cells; Cell Cycle
PubMed: 37751417
DOI: 10.1371/journal.pgen.1010928