11-cis-retinal and Blindness

Blindness is one of the most devastating conditions affecting the quality of life. Hereditary degenerative diseases, such as retinitis pigmentosa, are characterized by the progressive loss of photoreceptors, leading to complete blindness. No treatment is known, the current state-of-the-art of restoring vision are implanted electrode arrays. As a recently discovered alternative, optical neuromodulators, such as channelrhodopsin, allow new strategies for treating these diseases by imparting light-sensitivity onto the remaining retinal neurons after photoreceptor cell death. Retinal degeneration is a heterogeneous set of diseases with diverse secondary effects on the retinal circuitry. Successful treatment strategies have to take into account this diversity, as only the existing retinal hardware can serve as substrate for optogenetic intervention. The goal is to salvage the retinal ruins and to revert the leftover tissue into a functional visual sensor that operates as optimally as possible. Here, we discuss three different successful approaches that have been applied to degenerated mouse retina.

Topics: Animals; Blindness; Dependovirus; Genetic Therapy; Humans; Optogenetics; Retina; Retinal Ganglion Cells; Rhodopsin; Transduction, Genetic

Photoreceptor cells are the only retinal neurons that can absorb photons. Their degeneration due to some diseases or injuries leads to blindness. Retinal prostheses electrically stimulating surviving retinal cells and evoking a pseudo light sensation have been investigated over the past decade for restoring vision. Currently, a gene therapy approach is under development. Channelrhodopsin-2 derived from the green alga Chlamydomonas reinhardtii, is a microbial-type rhodopsin. Its specific characteristic is that it functions as a light-driven cation-selective channel. It has been reported that the channelrhodopsin-2 transforms inner light-insensitive retinal neurons to light-sensitive neurons. Herein, we introduce new strategies for restoring vision by using channelrhodopsins and discuss the properties of adeno-associated virus vectors widely used in gene therapy.

Topics: Algal Proteins; Animals; Blindness; Chlamydomonas reinhardtii; Genetic Therapy; Humans; Ion Pumps; Light Signal Transduction; Models, Biological; Rhodopsin; Signal Transduction

Inherited and age-related retinal degenerative diseases cause progressive loss of rod and cone photoreceptors, leading to blindness, but spare downstream retinal neurons, which can be targeted for optogenetic therapy. However, optogenetic approaches have been limited by either low light sensitivity or slow kinetics, and lack adaptation to changes in ambient light, and not been shown to restore object vision. We find that the vertebrate medium wavelength cone opsin (MW-opsin) overcomes these limitations and supports vision in dim light. MW-opsin enables an otherwise blind retinitis pigmenotosa mouse to discriminate temporal and spatial light patterns displayed on a standard LCD computer tablet, displays adaption to changes in ambient light, and restores open-field novel object exploration under incidental room light. By contrast, rhodopsin, which is similar in sensitivity but slower in light response and has greater rundown, fails these tests. Thus, MW-opsin provides the speed, sensitivity and adaptation needed to restore patterned vision.

Topics: Animals; Blindness; Cell Line; Cone Opsins; Dependovirus; Disease Models, Animal; Genetic Therapy; Genetic Vectors; Humans; Intravitreal Injections; Keratinocytes; Mice; Mice, Inbred C57BL; Optogenetics; Patch-Clamp Techniques; Retina; Retinal Cone Photoreceptor Cells; Retinal Degeneration; Rhodopsin; Treatment Outcome

The utility of stem cells and their progeny in adult transplantation models has been limited by poor survival and integration. We designed an injectable and bioresorbable hydrogel blend of hyaluronan and methylcellulose (HAMC) and tested it with two cell types in two animal models, thereby gaining an understanding of its general applicability for enhanced cell distribution, survival, integration, and functional repair relative to conventional cell delivery in saline. HAMC improves cell survival and integration of retinal stem cell (RSC)-derived rods in the retina. The pro-survival mechanism of HAMC is ascribed to the interaction of the CD44 receptor with HA. Transient disruption of the retinal outer limiting membrane, combined with HAMC delivery, results in significantly improved rod survival and visual function. HAMC also improves the distribution, viability, and functional repair of neural stem and progenitor cells (NSCs). The HAMC delivery system improves cell transplantation efficacy in two CNS models, suggesting broad applicability.

Topics: Animals; Blindness; Cell Survival; Hyaluronan Receptors; Hyaluronic Acid; Hydrogel, Polyethylene Glycol Dimethacrylate; Immunohistochemistry; Methylcellulose; Mice; Mice, Inbred C57BL; Mice, Knockout; Real-Time Polymerase Chain Reaction; Retina; Retinal Rod Photoreceptor Cells; Rhodopsin; Stem Cell Transplantation; Stem Cells; Stroke

We previously showed that blind rats whose vision was restored by gene transfer of Chlamydomonas channelrhodopsin-2 (ChR2) could only detect wavelengths less than 540 nm because of the action spectrum of the transgene product. Volvox-derived channelrhodopsin-1, VChR1, has a broader spectrum than ChR2. However, the VChR1 protein was mainly localized in the cytoplasm and showed weak ion channel properties when the VChR1 gene was transfected into HEK293 cells. We generated modified Volvox channelrhodopsin-1 (mVChR1), which is a chimera of Volvox channelrhodopsin-1 and Chlamydomonas channelrhodopsin-1 and demonstrated increased plasma membrane integration and dramatic improvement in its channel properties. Under whole-cell patch clamp, mVChR1-expressing cells showed a photo-induced current upon stimulation at 468-640 nm. The evoked currents in mVChR1-expressing cells were ~30 times larger than those in VChR1-expressing cells. Genetically, blind rats expressing mVChR1 via an adeno-associated virus vector regained their visual responses to light with wavelengths between 468 and 640 nm and their recovered visual responses were maintained for a year. Thus, mVChR1 is a candidate gene for gene therapy for restoring vision, and gene delivery of mVChR1 may provide blind patients access to the majority of the visible light spectrum.

Topics: Animals; Blindness; Chlamydomonas; Dependovirus; Genetic Therapy; Genetic Vectors; HEK293 Cells; Humans; Rats; Recombinant Fusion Proteins; Retina; Rhodopsin; Volvox

Irreversible blindness caused by loss of photoreceptors may be amenable to cell therapy. We previously demonstrated retinal repair and restoration of vision through transplantation of photoreceptor precursors obtained from postnatal retinas into visually impaired adult mice. Considerable progress has been made in differentiating embryonic stem cells (ESCs) in vitro toward photoreceptor lineages. However, the capability of ESC-derived photoreceptors to integrate after transplantation has not been demonstrated unequivocally. Here, to isolate photoreceptor precursors fit for transplantation, we adapted a recently reported three-dimensional (3D) differentiation protocol that generates neuroretina from mouse ESCs. We show that rod precursors derived by this protocol and selected via a GFP reporter under the control of a Rhodopsin promoter integrate within degenerate retinas of adult mice and mature into outer segment-bearing photoreceptors. Notably, ESC-derived precursors at a developmental stage similar to postnatal days 4-8 integrate more efficiently compared with cells at other stages. This study shows conclusively that ESCs can provide a source of photoreceptors for retinal cell transplantation.

Topics: Animals; Blindness; Cell Culture Techniques; Cell Differentiation; Cell- and Tissue-Based Therapy; Embryonic Stem Cells; Green Fluorescent Proteins; Mice; Photoreceptor Cells; Photoreceptor Cells, Vertebrate; Retina; Rhodopsin; Stem Cell Transplantation

Changes in gene expression were examined by microarray analysis during development of the eyed surface dwelling (surface fish) and blind cave-dwelling (cavefish) forms of the teleost Astyanax mexicanus De Filippi, 1853. The cross-species microarray used surface and cavefish RNA hybridized to a DNA chip prepared from a closely related species, the zebrafish Danio rerio Hamilton, 1822. We identified a total of 67 differentially expressed probe sets at three days post-fertilization: six upregulated and 61 downregulated in cavefish relative to surface fish. Many of these genes function either in eye development and/or maintenance, or in programmed cell death. The upregulated probe set showing the highest mean fold change was similar to the human ubiquitin specific protease 53 gene. The downregulated probe sets showing some of the highest fold changes corresponded to genes with roles in eye development, including those encoding gamma crystallins, the guanine nucleotide binding proteins Gnat1 and Gant2, a BarH-like homeodomain transcription factor, and rhodopsin. Downregulation of gamma-crystallin and rhodopsin was confirmed by in situ hybridization and immunostaining with specific antibodies. Additional downregulated genes encode molecules that inhibit or activate programmed cell death. The results suggest that cross-species microarray can be used for identifying differentially expressed genes in cavefish, that many of these genes might be involved in eye degeneration via apoptotic processes, and that more genes are downregulated than upregulated in cavefish, consistent with the predominance of morphological losses over gains during regressive evolution.

Topics: Adaptation, Biological; Animals; Blindness; DNA Primers; Fishes; gamma-Crystallins; Gene Expression Regulation, Developmental; Genetic Markers; Heterotrimeric GTP-Binding Proteins; In Situ Hybridization; Mexico; Microarray Analysis; Rhodopsin; Species Specificity

To estimate the mean rates of ocular function loss in patients with autosomal recessive retinitis pigmentosa due to USH2A mutations.. In 125 patients with USH2A mutations, longitudinal regression was used to estimate mean rates of change in Snellen visual acuity, Goldmann visual field area (V4e white test light), and 30-Hz (cone) full-field electroretinogram amplitude. These rates were compared with those of previously studied cohorts with dominant retinitis pigmentosa due to RHO mutations and with X-linked retinitis pigmentosa due to RPGR mutations. Rates of change in patients with the Cys759Phe mutation, the USH2A mutation associated with nonsyndromic disease, were compared with rates of change in patients with the Glu767fs mutation, the most common USH2A mutation associated with Usher syndrome type II (i.e., retinitis pigmentosa and hearing loss).. Mean annual exponential rates of decline for the USH2A patients were 2.6% for visual acuity, 7.0% for visual field area, and 13.2% for electroretinogram amplitude. The rate of acuity loss fell between the corresponding rates for the RHO and RPGR patients, whereas the rates for field and ERG amplitude loss were faster than those for the RHO and RPGR patients. No significant differences were found for patients with the Cys759Phe mutation versus patients with the Glu767fs mutation.. On average, USH2A patients lose visual acuity faster than RHO patients and slower than RPGR patients. USH2A patients lose visual field and cone electroretinogram amplitude faster than patients with RHO or RPGR mutations. Patients with a nonsyndromic USH2A mutation have the same retinal disease course as patients with syndromic USH2A disease.

Topics: Adolescent; Adult; Alleles; Blindness; Child; Disease Progression; Electroretinography; Extracellular Matrix Proteins; Eye Proteins; Follow-Up Studies; Genes, Recessive; Genotype; Humans; Middle Aged; Mutation; Retinitis Pigmentosa; Rhodopsin; Tomography, Optical Coherence; Visual Acuity; Visual Fields; Young Adult

The blind cavefish Astyanax mexicanus undergoes bilateral eye degeneration during embryonic development. Despite the absence of light in the cave environment, cavefish have retained a structurally intact pineal eye. We show here that contrary to visual degeneration in the bilateral eyes, the cavefish pineal eye has conserved the ability to detect light. Larvae of two different Astyanax cavefish populations and the con-specific sighted surface-dwelling form (surface fish) respond similarly to light dimming by shading the pineal eye. As a response to shading, cavefish larvae swim upward vertically. This behavior resembles that of amphibian tadpoles rather than other teleost larvae, which react to shadows by swimming downward. The shadow response is highest at 1.5-days post-fertilization (d.p.f.), gradually diminishes, and is virtually undetectable by 7.5 d.p.f. The shadow response was substantially reduced after surgical removal of the pineal gland from surface fish or cavefish larvae, indicating that it is based on pineal function. In contrast, removal of one or both bilateral eye primordia did not affect the shadow response. Consistent with its light detecting capacity, immunocytochemical studies indicate that surface fish and cavefish pineal eyes express a rhodopsin-like antigen, which is undetectable in the degenerating bilateral eyes of cavefish larvae. We conclude that light detection by the pineal eye has been conserved in cavefish despite a million or more years of evolution in complete darkness.

Topics: Animals; Blindness; Eye; Fishes; Larva; Pineal Gland; Rhodopsin

One eye of rd12 mice received a sub-retinal injection of a vector carrying normal human RPE65 cDNA at post-natal day 18, and at 6- and 13-months of age. Electroretinograms (ERGs) and visual-evoked potentials (VEPs) were recorded to luminance, and to spatially and temporally modulated stimuli to assess the consequences of delayed treatment on visual pathway function. Early treatment resulted in better overall retinal rescue and better rescue of cone-mediated function. VEPs to low temporal frequency luminance modulation were well preserved at all but the oldest treatment age and corresponded to predictions based on the amount of retinal rescue. In contrast, VEPs to high frequency spatially and temporally modulated stimuli were impaired even at the earliest age. These results provide further support that early treatment in human LCA will have the most hope for optimal visual performance.

Topics: Animals; Blindness; Dark Adaptation; Disease Models, Animal; Electroretinography; Evoked Potentials, Visual; Genetic Therapy; Mice; Mice, Mutant Strains; Retina; Rhodopsin; Time Factors; Vision Tests; Visual Acuity; Visual Cortex

To report the phenotype and characterization of a new, naturally occurring mouse model of hereditary retinal degeneration (rd12).. The retinal phenotype of rd12 mice were studied using serial indirect ophthalmoscopy, fundus photography, electroretinography (ERG), genetic analysis including linkage studies and gene identification, immunohistochemistry, and biochemical analysis.. Mice homozygous for the rd12 mutation showed small punctate white spots on fundus examination at 5 months of age. The retina in the rd12 homozygote had a normal appearance at the light microscopic level until 6 weeks of age when occasional voids appeared in the outer segments (OS) of the photoreceptor (PR) cells. The outer nuclear layer (ONL) appeared normal until 3 months of age though more obvious voids were detected in the OS. By 7 months of age, 6 to 8 layers of ONL remained in the mutant retina, and the OS were obviously shorter. The first sign of retinal degeneration was detected at the electron microscopic level around 3 weeks of age when occasional small lipid-like droplets were detected in the retinal pigment epithelium (RPE). By 3 months of age, much larger, lipid-like droplets accumulated in RPE cells accompanied by some OS degeneration. While the histology indicated a relatively slow retinal degeneration in the rd12 homozygous mutant mice, the rod ERG response was profoundly diminished even at 3 weeks of age. Genetic analysis showed that rd12 was an autosomal recessive mutation and mapped to mouse chromosome 3 closely linked to D3Mit19, a location known to be near the mouse Rpe65 gene. Sequence analysis showed that the mouse retinal degeneration is caused by a nonsense mutation in exon 3 of the Rpe65 gene, and the gene symbol for the rd12 mutation has been updated to Rpe65rd12 to reflect this. No RPE65 expression, 11-cis retinal, or rhodopsin could be detected in retinas from rd12 homozygotes, while retinyl esters were found to accumulate in the retinal pigment epithelium (RPE).. Mutations in the retinal pigment epithelium gene encoding RPE65 cause an early onset autosomal recessive form of human retinitis pigmentosa, known as Leber congenital amaurosis (LCA), which results in blindness or severely impaired vision in children. A naturally arising mouse Rpe65 mutation provides a good model for studying the pathology of human RPE65 mutations and the effects of retinyl ester accumulation.

Topics: Animals; Blindness; Carrier Proteins; cis-trans-Isomerases; Codon, Nonsense; Disease Models, Animal; Electroretinography; Exons; Eye Proteins; Female; Fluorescent Antibody Technique, Indirect; Humans; Male; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Ophthalmoscopy; Phenotype; Photoreceptor Cells, Vertebrate; Pigment Epithelium of Eye; Retinal Degeneration; Retinaldehyde; Rhodopsin

An unusual retinal vascular morphology in an enucleated eye from a patient with Leber congenital amaurosis (LCA) has been associated with a mutation in AIPL1. The AIPL1 protein is expressed in the pineal gland and retinal photoreceptors. In the retina, AIPL1 is expressed in both developing cone and rod photoreceptors, but it is restricted to rod photoreceptors in the adult human retina. Therefore, this study was conducted to determine the photoreceptor phenotype in this LCA patient to determine if photoreceptors were differentially affected.. Additional genetic screening was performed and the consequences of the H82Y amino acid substitution characterized in an in vitro assay of NUB1 modulation. The morphology of the photoreceptors was examined by light and electron microscopy. Immunohistochemistry and immunofluorescent confocal microscopy was performed using a range of retinal photoreceptor markers.. Transfection of the H82Y mutant AIPL1 in SK-N-SH cells revealed a normal subcellular localization and solubility but resulted in an increased ability of AIPL1 to redistribute GFP-NUB1 to the cytoplasm and resolve NUB1 fragment inclusion formation. Morphologically, the LCA retina appeared to be cone-dominant with a single layer of cone-like cells remaining in the central retina. Photoreceptor outer segments were absent and the surviving residual inner segments were severely shortened. Severe degeneration of the LCA retina was associated with upregulation of glial fibrillary acidic protein (GFAP). No signal was detected for AIPL1, rhodopsin, or L/M and S cone opsins in the LCA retina. Double labeling with peanut agglutinin (PNA) and wheat germ agglutinin (WGA) supported a cone-dominant phenotype for the surviving photoreceptors in the LCA retina, as did double labeling for cone arrestin, and rod and cone recoverin. The cone arrestin signal was restricted to the residual photoreceptor inner segments and was not detected in the cell bodies, axons, or axon terminals of the surviving photoreceptors. Recoverin immunoreactivity was most intense in the residual photoreceptor inner segments.. The phenotype in this patient suggests that although AIPL1 is required for the development of normal rod and cone photoreceptor function, it might only be essential for rod and not cone survival in the adult.

Topics: Adaptor Proteins, Signal Transducing; Adult; Aged; Blindness; Blotting, Western; Carrier Proteins; cis-trans-Isomerases; Eye Proteins; Fluorescent Antibody Technique, Indirect; Glial Fibrillary Acidic Protein; Guanylate Cyclase; Homeodomain Proteins; Humans; Male; Microscopy, Confocal; Microscopy, Electron; Phenotype; Polymorphism, Single-Stranded Conformational; Receptors, Cell Surface; Retinal Degeneration; Retinal Rod Photoreceptor Cells; Rhodopsin; Trans-Activators; Transfection; Up-Regulation

Continuous exposure to light, even at relatively low intensities, leads to retinal damage and blindness in wild-type animals. However, the molecular mechanisms underlying constant-light-induced blindness are poorly understood. It has been presumed that the visual impairment resulting from long-term, continuous exposure to ambient light is a secondary consequence of the effects of light on retinal morphology, but this has not been addressed.. To characterize the mechanism underlying light-induced blindness, we applied a molecular genetic approach using the fruit fly, Drosophila melanogaster. We found that the temporal loss of the photoresponse was paralleled by a gradual decline in the concentration of rhodopsin. The decline in rhodopsin and the visual response were suppressed by a C-terminal truncation of rhodopsin, by mutations in arrestin, and by elimination of a lysosomal protein, Sunglasses. Conversely, the visual impairment was greatly enhanced by mutation of the rhodopsin phosphatase, rdgC. Surprisingly, the mutations that suppressed light-induced blindness did not reduce the severity of the retinal degeneration resulting from constant light. Moreover, mutations known to suppress retinal degeneration did not ameliorate the light-induced blindness.. These data demonstrate that the constant light-induced blindness and retinal degeneration result from defects in distinct molecular pathways. Our results support a model in which visual impairment caused by continuous illumination occurs through an arrestin-dependent pathway that promotes degradation of rhodopsin.

Topics: Animals; Arrestin; Blindness; Calcium-Binding Proteins; Drosophila melanogaster; Drosophila Proteins; Electroretinography; Light; Microscopy, Electron, Transmission; Models, Biological; Mutation; Phosphoprotein Phosphatases; Photoperiod; Photoreceptor Cells, Invertebrate; Proteins; Retinal Degeneration; Rhodopsin

Visual pigments (rhodopsins) are composed of a chromophore (vitamin A derivative) bound to a protein moiety embedded in the retinal membranes. Animals cannot synthesize the visual chromophore de novo but rely on the uptake of carotenoids, from which vitamin A is formed enzymatically by oxidative cleavage. Despite its importance, the enzyme catalyzing the key step in vitamin A formation resisted molecular analyses until recently, when the successful cloning of a cDNA encoding an enzyme with beta,beta-carotene-15,15'-dioxygenase activity from Drosophila was reported. To prove its identity with the key enzyme for vitamin A formation in vivo, we analyzed the blind Drosophila mutant ninaB. In two independent ninaB alleles, we found mutations in the gene encoding the beta,beta-carotene-15,15'-dioxygenase. These mutations lead to a defect in vitamin A formation and are responsible for blindness of these flies.

Topics: Amino Acid Sequence; Amino Acid Substitution; Animals; Base Sequence; beta-Carotene 15,15'-Monooxygenase; Blindness; Chickens; Cloning, Molecular; Crosses, Genetic; Drosophila melanogaster; Drosophila Proteins; Female; Heterozygote; Humans; Male; Molecular Sequence Data; Mutagenesis, Site-Directed; Mutation; Oxygenases; Point Mutation; Recombinant Proteins; Reverse Transcriptase Polymerase Chain Reaction; Rhodopsin; RNA, Messenger; Sequence Alignment; Sequence Homology, Amino Acid; Vitamin A; Vitamin A Deficiency

Visual pigments in the regressed eye and pineal of the depigmented neotenic urodele, the blind cave salamander (Proteus anguinus anguinus), were studied by immunocytochemistry with anti-opsin antibodies. The study included light- and electron-microscopic investigations of both the eye and the pineal organ. A comparison was made with the black pigmented subspecies Proteus anguinus parkelj (black proteus), which has a normal eye structure. In the retina of the black proteus, we found principal rods, red-sensitive cones and a third photoreceptor type, which might represent a blue- or UV-sensitive cone. Photoreceptors in the regressed eye of the blind cave salamanders from the Planina cave contained degenerate outer segments, consisting of a few whorled discs and irregular clumps of membranes. The great majority of these outer segments showed immunolabelling for the red-sensitive cone opsin and only a few of them were found to be positive for rhodopsin. An even more pronounced degeneration was observed in the photoreceptors of the animals derived from the Otovec doline, which are completely devoid of an outer segment, most of them not even possessing an inner segment. Even in some of these highly degenerate cells, the presence of rhodopsin could be detected in the plasma membrane; however, immunoreactions with antibodies recognizing cone visual pigment were negative. In the pineals of all studied animals, the degenerate photoreceptor outer segments were recognized exclusively by the antibody against the red-sensitive cone opsin. The presence of immunopositive visual pigments indicates the possibility of a retained light sensitivity in the blind cave salamander photoreceptors.

Topics: Animals; Antibodies, Monoclonal; Biological Evolution; Blindness; Immunohistochemistry; Microscopy, Immunoelectron; Pineal Gland; Retinal Cone Photoreceptor Cells; Retinal Rod Photoreceptor Cells; Rhodopsin; Urodela

Ten rhodopsin mutations have been found in a screen of 282 subjects with retinitis pigmentosa (RP), 76 subjects with Leber congenital amaurosis, and 3 subjects with congenital stationary night blindness. Eight of these mutations (gly51-to-ala, val104-to-ile, gly106-to-arg, arg135-to-gly, cys140-to-ser, gly188-to-glu, val209-to-met, and his211-to-arg) produce amino acid substitutions, one (gln64-to-ter) introduces a stop codon, and one changes a guanosine in the intron 4 consensus splice donor sequence to thymidine. Cosegregation of RP with gln64-to-ter, gly106-to-arg, arg135-to-gly, cys140-to-ser, gly188-to-glu, his211-to-arg, and the splice site guanosine-to-thymidine indicates that these mutations are likely to cause retinal disease. Val104-to-ile does not cosegregate and is therefore unlikely to be related to retinal disease. The relevance of gly51-to-ala and val209-to-met remains to be determined. The finding of gln64-to-ter in a family with autosomal dominant RP is in contrast to a recent report of a recessive disease phenotype associated with the rhodopsin mutation glu249-to-ter. In the present screen, all of the mutations that cosegregate with retinal disease were found among patients with RP. The mutations described here bring to 35 the total number of amino acid substitutions identified thus far in rhodopsin that are associated with RP. The distribution of the substitutions along the polypeptide chain is significantly nonrandom: 63% of the substitutions involve those 19% of amino acids that are identical among vertebrate visual pigments sequenced to date.

Topics: Alleles; Blindness; DNA Mutational Analysis; Female; Gene Frequency; Humans; Male; Mutation; Night Blindness; Pedigree; Polymerase Chain Reaction; Protein Conformation; Retinitis Pigmentosa; Rhodopsin

A number of mutations in the rhodopsin gene have been shown to cause both dominant and recessive retinitis pigmentosa. Here we describe another phenotype associated with a defect in this gene. We discovered a patient with congenital stationary night blindness who carries the missense mutation Ala292Glu. When coupled with 11-cis-retinal in vitro, Ala292Glu rhodopsin is able to activate transducin in a light-dependent manner like wild-type rhodopsin. However, without a chromophore, Ala292Glu opsin anomalously activates transducin. We speculate that the rod dysfunction in this patient is due to an abnormal, continuous activation of transducin by mutant opsin molecules in photoreceptor outer segments.

Topics: Adult; Amino Acid Sequence; Base Sequence; Blindness; Darkness; DNA; Heterozygote; Humans; Male; Models, Biological; Molecular Sequence Data; Mutation; Rhodopsin; Transducin

Topics: Blindness; Eye Proteins; Humans; Mutation; Photoreceptor Cells; Retinal Pigments; Retinitis Pigmentosa; Rhodopsin; Rod Opsins

In order to determine whether blindness in the rd strain of Rhode Island Red chickens is due to a defect in the vitamin A (visual) cycle, spectroscopy, high performance liquid chromatography, and immunochemical techniques were used to compare the amounts of rhodopsin, interstitial retinol-binding protein, and vitamin A compounds in the dark-adapted eyes of homozygous rd and heterozygous carriers. In both groups of chickens, (up to 6 weeks post-hatching) the distribution of stored vitamin A differed from other vertebrates (mammals, amphibians, fish) in that more than half of the retinyl palmitate/stearate occurred in the neurosensory retina. The 11-cis isomer accounted for nearly 100% of the retinyl palmitate/stearate in the neurosensory retinas of both groups. In the pigmented layers (pigment epithelium and choroid) the 11-cis isomer amounted to 70.1 +/- 4.2% in the carrier, and 65.1 +/- 2.9% in the rd birds. With respect to their content of rhodopsin, IRBP, retinyl palmitate/stearate and unesterified retinol, (both 11-cis and all-trans isomers) no significant difference could be demonstrated between the eyes of rd and carrier chickens (3 days and 28 days post-hatching). These results therefore demonstrate that the ocular tissues of rd chickens do not lack IRBP, the putative extracellular transport protein for vitamin A, that these tissues synthesize and store the 11-cis isomer of vitamin A, and that the 11-cis isomer is used to form rhodopsin.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Blindness; Chickens; Chromatography, High Pressure Liquid; Electrophoresis, Polyacrylamide Gel; Eye Proteins; Mutation; Poultry Diseases; Retina; Retinal Pigments; Retinol-Binding Proteins; Rhodopsin; Vitamin A

Systemic immunization with purified homologous rhodopsin from retinal outer segments induced blindness in primates (Macaca mulatta). Inflammation and characteristic retinal changes were the earliest clinical signs of the disease. Perivasculitis, subretinal exudations and bullous detachments of the retina were progressive and unrelenting pathological processes leading to rapid and irreversible visual deterioration. Electroretinographic responses (ERG) at this stage of the disorder became abolished. Antibodies and delayed hypersensitivity to rhodopsin were demonstrated only in the experimental diseased animals. Homologous visual purple appears to be organ and immunopathologically specific. Histological confirmation of these findings showed a pathological spectrum of destructive alterations confirmed specifically to the outer segments of the entire retina. The pathologic reaction was supported by a distinct and pronounced granulomatous inflammatory response.

Topics: Animals; Blindness; Electroretinography; Female; Haplorhini; Immunization; Macaca mulatta; Male; Pigment Epithelium of Eye; Retinal Diseases; Retinal Pigments; Rhodopsin; Uveitis

Topics: Animals; Autoimmune Diseases; Blindness; Disease Models, Animal; Haplorhini; Macaca mulatta; Retinal Degeneration; Retinal Pigments; Rhodopsin