11-cis-retinal and Eye-Diseases--Hereditary

Vision in dim-light conditions is triggered by photoactivation of rhodopsin, the visual pigment of rod photoreceptor cells. Rhodopsin is made of a protein, the G protein coupled receptor (GPCR) opsin, and the chromophore 11-cis-retinal. Vertebrate rod opsin is the GPCR best characterized at the atomic level of detail. Since the release of the first crystal structure 20 years ago, a huge number of structures have been released that, in combination with valuable spectroscopic determinations, unveiled most aspects of the photobleaching process. A number of spontaneous mutations of rod opsin have been found linked to vision-impairing diseases like autosomal dominant or autosomal recessive retinitis pigmentosa (adRP or arRP, respectively) and autosomal congenital stationary night blindness (adCSNB). While adCSNB is mainly caused by constitutive activation of rod opsin, RP shows more variegate determinants affecting different aspects of rod opsin function. The vast majority of missense rod opsin mutations affects folding and trafficking and is linked to adRP, an incurable disease that awaits light on its molecular structure determinants. This review article summarizes all major structural information available on vertebrate rod opsin conformational states and the insights gained so far into the structural determinants of adCSNB and adRP linked to rod opsin mutations. Strategies to design small chaperones with therapeutic potential for selected adRP rod opsin mutants will be discussed as well.

Topics: Animals; Crystallography, X-Ray; Eye Diseases, Hereditary; Genetic Diseases, X-Linked; Humans; Myopia; Night Blindness; Protein Structure, Secondary; Retinitis Pigmentosa; Rhodopsin

Topics: Animals; Eye Diseases, Hereditary; Humans; Mutation; Rhodopsin

Topics: Amino Acid Sequence; Eye Diseases, Hereditary; Eye Proteins; Humans; Intermediate Filament Proteins; Membrane Glycoproteins; Molecular Sequence Data; Nerve Tissue Proteins; Peripherins; Point Mutation; Retinitis Pigmentosa; Rhodopsin

Over 100 mutations in the rhodopsin gene have been linked to a spectrum of retinopathies that include retinitis pigmentosa and congenital stationary night blindness. Though most of these variants exhibit a loss of function, the molecular defects caused by these underlying mutations vary considerably. In this work, we utilize deep mutational scanning to quantitatively compare the plasma membrane expression of 123 known pathogenic rhodopsin variants in the presence and absence of the stabilizing cofactor 9-cis-retinal. We identify 69 retinopathy variants, including 20 previously uncharacterized variants, that exhibit diminished plasma membrane expression in HEK293T cells. Of these apparent class II variants, 67 exhibit a measurable increase in expression in the presence of 9-cis-retinal. However, the magnitude of the response to this molecule varies considerably across this spectrum of mutations. Evaluation of the observed shifts relative to thermodynamic estimates for the coupling between binding and folding suggests underlying differences in stability constrains the magnitude of their response to retinal. Nevertheless, estimates from computational modeling suggest that many of the least sensitive variants also directly compromise binding. Finally, we evaluate the functional properties of three previous uncharacterized, retinal-sensitive variants (ΔN73, S131P, and R135G) and show that two of these retain residual function in vitro. Together, our results provide a comprehensive experimental characterization of the proteostatic properties of retinopathy variants and their response to retinal.

Topics: Diterpenes; Drug Resistance; Eye Diseases, Hereditary; HEK293 Cells; Humans; Mutation; Retinaldehyde; Rhodopsin

The G90D mutation in the rhodopsin gene leads to autosomal dominant congenital stationary night blindness (CSNB) in patients. This occurs because the G90D mutant protein cannot efficiently bind chromophore and is constitutively active. To combat this mutation, we designed and characterized two different hammerhead ribozymes to cleave G90D transcript. In vitro testing showed that the G90D1 ribozyme efficiently and specifically cleaved the mutant transcript while G90D2 cleaved both WT and mutant transcript. AAV-mediated delivery of G90D1 under the control of the mouse opsin promoter (MOP500) to G90D transgenic eyes showed that the ribozyme partially retarded the functional degeneration (as measured by electroretinography [ERG]) associated with this mutation. These results suggest that with additional optimization, ribozymes may be a useful part of the gene therapy knockdown strategy for dominant retinal disease.

Topics: Animals; Biocatalysis; Dependovirus; Electroretinography; Eye Diseases, Hereditary; Genetic Diseases, X-Linked; Genetic Therapy; Genetic Vectors; Humans; Mice, Transgenic; Mutant Proteins; Mutation; Myopia; Night Blindness; Rhodopsin; RNA; RNA, Catalytic; Substrate Specificity; Transcription, Genetic

Congenital stationary night blindness (CSNB) is an inherited and non-progressive retinal dysfunction. Here, we present the crystal structure of CSNB-causing T94I

Topics: Binding Sites; Catalytic Domain; Darkness; Eye Diseases, Hereditary; Genetic Association Studies; Genetic Diseases, X-Linked; Humans; Models, Biological; Models, Molecular; Mutation; Myopia; Night Blindness; Protein Binding; Protein Conformation; Protein Stability; Rhodopsin; Schiff Bases; Structure-Activity Relationship; Thermodynamics

We present active-state structures of the G protein-coupled receptor (GPCRs) rhodopsin carrying the disease-causing mutation G90D. Mutations of G90 cause either retinitis pigmentosa (RP) or congenital stationary night blindness (CSNB), a milder, non-progressive form of RP. Our analysis shows that the CSNB-causing G90D mutation introduces a salt bridge with K296. The mutant thus interferes with the E113Q-K296 activation switch and the covalent binding of the inverse agonist 11-cis-retinal, two interactions that are crucial for the deactivation of rhodopsin. Other mutations, including G90V causing RP, cannot promote similar interactions. We discuss our findings in context of a model in which CSNB is caused by constitutive activation of the visual signalling cascade.

Topics: Arrestin; Crystallography, X-Ray; Eye Diseases, Hereditary; Genetic Diseases, X-Linked; HEK293 Cells; Humans; Models, Molecular; Mutation, Missense; Myopia; Night Blindness; Protein Binding; Protein Stability; Protein Structure, Secondary; Protein Structure, Tertiary; Rhodopsin; Schiff Bases; Structural Homology, Protein; Transition Temperature

To detect genetic mutations associated with autosomal dominant congenital stationary night blindness (ADCSNB) in a family from Henan province.. Genomic DNA was extracted from peripheral blood samples of 14 family members. Based on 3 genes reported previously, PCR primers were designed and corresponding exons containing the mutation sites were amplified with PCR. PCR products were purified and directly sequenced.. A c.281C>T heterozygous missense mutation was detected in RHO gene in all of the patients. This mutation can cause a change of the protein structure (p.Thr94Ile). The same mutation was not detected in normal individuals from the family and 50 normal controls.. A c.281C>T mutation in RHO gene is responsible for the onset of ADCSNB in this Chinese family and results in symptoms of night blindness.

Topics: Adult; Amino Acid Sequence; China; DNA Mutational Analysis; Eye Diseases, Hereditary; Female; Genetic Diseases, X-Linked; Genetic Predisposition to Disease; Humans; Male; Molecular Sequence Data; Mutation, Missense; Myopia; Night Blindness; Rhodopsin; Sequence Alignment

Several point mutations in rhodopsin cause retinal diseases including congenital stationary night blindness and retinitis pigmentosa. The mechanism by which a single amino acid residue substitution leads to dysfunction is poorly understood at the molecular level. A G90D point mutation in rhodopsin causes constitutive activity and leads to congenital stationary night blindness. It is unclear which perturbations the mutation introduces and how they can cause the receptor to be constitutively active. To reveal insight into these mechanisms, we characterized the perturbations introduced into dark state G90D rhodopsin from a transgenic mouse model expressing exclusively the mutant rhodopsin in rod photoreceptor cells. UV-visible absorbance spectroscopy revealed hydroxylamine accessibility to the chromophore-binding pocket of dark state G90D rhodopsin, which is not detected in dark state wild-type rhodopsin but is detected in light-activated wild-type rhodopsin. Single-molecule force spectroscopy suggested that the structural changes introduced by the mutation are small. Dynamic single-molecule force spectroscopy revealed that, compared with dark state wild-type rhodopsin, the G90D mutation decreased energetic stability and increased mechanical rigidity of most structural regions in the dark state mutant receptor. The observed structural, energetic, and mechanical changes in dark state G90D rhodopsin provide insights into the nature of perturbations caused by a pathological point mutation. Moreover, these changed properties observed for dark state G90D rhodopsin are consistent with properties expected for an active state.

Topics: Amino Acid Sequence; Animals; Eye Diseases, Hereditary; Genetic Diseases, X-Linked; Mice; Mice, Transgenic; Microscopy, Atomic Force; Molecular Sequence Data; Mutation; Myopia; Night Blindness; Point Mutation; Protein Structure, Secondary; Protein Structure, Tertiary; Receptors, G-Protein-Coupled; Rhodopsin; Rod Cell Outer Segment; Spectrophotometry; Stress, Mechanical; Thermodynamics; Ultraviolet Rays

Two different mutations at Gly-90 in the second transmembrane helix of the photoreceptor protein rhodopsin have been proposed to lead to different phenotypes. G90D has been classically associated with congenital night blindness, whereas the newly reported G90V substitution was linked to a retinitis pigmentosa phenotype. Here, we used Val/Asp replacements of the native Gly at position 90 to unravel the structure/function divergences caused by these mutations and the potential molecular mechanisms of inherited retinal disease. The G90V and G90D mutants have a similar conformation around the Schiff base linkage region in the dark state and same regeneration kinetics with 11-cis-retinal, but G90V has dramatically reduced thermal stability when compared with the G90D mutant rhodopsin. The G90V mutant also shows, like G90D, an altered photobleaching pattern and capacity to activate Gt in the opsin state. Furthermore, the regeneration of the G90V mutant with 9-cis-retinal was improved, achieving the same A(280)/A(500) as wild type isorhodopsin. Hydroxylamine resistance was also recovered, indicating a compact structure around the Schiff base linkage, and the thermal stability was substantially improved when compared with the 11-cis-regenerated mutant. These results support the role of thermal instability and/or abnormal photoproduct formation in eliciting a retinitis pigmentosa phenotype. The improved stability and more compact structure of the G90V mutant when it was regenerated with 9-cis-retinal brings about the possibility that this isomer or other modified retinoid analogues might be used in potential treatment strategies for mutants showing the same structural features.

Topics: Amino Acid Substitution; Animals; Cattle; Cell Line, Tumor; COS Cells; Diterpenes; Eye Diseases, Hereditary; Genetic Diseases, X-Linked; Humans; Mutation, Missense; Myopia; Night Blindness; Protein Stability; Protein Structure, Tertiary; Retinaldehyde; Retinitis Pigmentosa; Rhodopsin; Structure-Activity Relationship

Mutations in the photoreceptor transcription factor cone-rod homeobox (CRX) have been identified in patients with several forms of retinal degenerative disease. To investigate the mechanisms by which these mutations cause photoreceptor degeneration, CRX constructs representing eleven known mutations, as well as a set of C-terminal deletions, were generated and tested for their ability to activate a rhodopsin-luciferase reporter in a transient cell transfection assay. To further define functional domains, several Gal4dbd-Crx fusions were similarly tested using a Gal4 response element containing heterologous promoter. This analysis demonstrated that the C-terminal region, between amino acids 200 and 284, is essential for CRX-mediated transcriptional activation. Consistent with this, four mutants carrying C-terminal truncations demonstrated significantly reduced transcriptional activation. Confirming the importance of the homeodomain (HD), four of the five mutants carrying HD missense mutations displayed altered transactivating activity, either decreased (three) or increased (one). In vitro protein-DNA binding assays (EMSAs) with CRX-HD peptides representing the three HD mutants with decreased transactivating activity, indicated that the alteration was due to reduced, but not abolished, DNA binding to CRX targets. Taken together, these results support the hypothesis that CRX mutations involved in human photoreceptor degeneration act by impairing CRX-mediated transcriptional regulation of the photoreceptor genes. However, a clear relationship between the magnitude of biochemical abnormality and degree of disease severity was not observed, suggesting that other genetic and environmental modifiers may also contribute to the disease phenotype.

Topics: Amino Acid Sequence; Base Sequence; DNA; Eye Diseases, Hereditary; Gene Expression Regulation; Homeodomain Proteins; Molecular Sequence Data; Mutation; Promoter Regions, Genetic; Protein Binding; Retinal Cone Photoreceptor Cells; Retinal Degeneration; Retinal Rod Photoreceptor Cells; Rhodopsin; Sequence Analysis, Protein; Structure-Activity Relationship; Trans-Activators

Several ophthalmic conditions manifest a flecked retina. Developing an understanding of their clinical presentations will enable the practitioner to most appropriately manage these conditions.. A 27-year-old Middle Eastern woman manifested flecked retinas and nyctalopia. She had been given a diagnosis of retinitis punctata albescens, an inherited, progressive, night blindness; however, the medical history and clinical findings were not consistent with this disorder. Rather, they were consistent with fundus albipunctatus, an autosomal recessive, stationary, night blindness. The clinical presentation of fundus albipunctatus is characterized by discrete, white dots at the level of the retinal pigment epithelium and stable night blindness. A prolonged time for dark adaptation is required to produce normal amplitude electroretinograms in fundus albipunctatus as the result of a delay in the regeneration of rhodopsin. An electroretinogram administered after a prolonged dark adaptation time confirmed the diagnosis of stationary night blindness.. In order to ensure an accurate diagnosis for fundus albipunctatus, it is important to be aware of the clinical characteristics and appropriate electroretinogram protocol for this disorder.

Topics: Adult; Dark Adaptation; Diagnosis, Differential; Electroretinography; Eye Diseases, Hereditary; Female; Fundus Oculi; Humans; Night Blindness; Retinal Diseases; Retinal Rod Photoreceptor Cells; Rhodopsin; Syndrome

A family with 1 case of retinitis pigmentosa (III-1) and 2 cases of Oguchi's disease (III-2, 3) was examined in terms of electrophysiology as well as molecular biology. The proband (III-3), a 42-year-old female, and 2 older brothers (III-1, 2, aged 52 and 45 years) and 2 unaffected members in the same family participated in this study. Corrected visual acuities of the individuals with Oguchi's disease (III-2, 3) were 1.2. On funduscopy, blood vessels stood out in relief against a metallic-appearing background and a Mizuo-Nakamura phenomenon was evident. Full-field electroretinograms (ERGs) recorded from the proband were indicative of rod dystrophy, but results of other electrophysiological examinations (multifocal ERG, pattern ERG and visual-evoked cortical potential recordings) were within normal limits. Patient III-1 had corrected visual acuities of RE 20 cm/m.m. and LE 30 cm/n.d., severe chorioretinal atrophy in both fundi, and full-field ERG revealed rod-cone dystrophy. Mutation of the arrestin gene (1147de1A) was detected in all 3 patients. Visual function in each patient coincides with that of retinitis pigmentosa or Oguchi's disease, respectively.

Topics: Adult; Arrestin; Base Sequence; Electroretinography; Evoked Potentials, Visual; Eye Diseases, Hereditary; Female; Fundus Oculi; Humans; Male; Middle Aged; Mutation; Pedigree; Retinitis Pigmentosa; Rhodopsin; Vision, Ocular

By screening blood samples from patients with autosomal dominant retinitis pigmentosa, we found in one of the families a rhodopsin mutation (Pro-267-Leu), which segregates with the disease in two affected and five unaffected family members. Here, we present the results of the clinical evaluation of the family, including full-field electroretinography from the two affected family members. A 25-year-old family member with the mutation had an almost normal electrophysiological retinal response. The patient's father, who was also heterozygous for the mutation and had mild subjective symptoms of retinitis pigmentosa, demonstrated a substantially preserved retinal function. Our results suggest that the Pro-267-Leu rhodopsin mutation is associated with a very mild phenotype of retinitis pigmentosa. Young patients with the disease may have minimal pathological changes in the electroretinogram and some patients with few symptoms may be affected without acquiring a diagnosis of eye disease.

Topics: Adult; Chromosome Aberrations; Chromosome Disorders; Electroretinography; Exons; Eye Diseases, Hereditary; Family Health; Female; Genes, Dominant; Genetic Testing; Heterozygote; Humans; Male; Middle Aged; Pedigree; Phenotype; Point Mutation; Proline; Retinitis Pigmentosa; Rhodopsin; Sequence Analysis, DNA; Sweden; Visual Acuity