11-cis-retinal and Myopia

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: Adult; Child; Female; Follow-Up Studies; Humans; Infant; Male; Mutation; Myopia; Pedigree; Prognosis; Retinitis Pigmentosa; Retrospective Studies; Rhodopsin; Scleral Diseases; Severity of Illness Index

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

To investigate the rhodopsin expression in form-deprived and defocus myopia in guinea pig and study the relationship between the rhodopsin expression and experimental myopia.. Fourty guinea pigs were randomized into the form-deprived group and the defocus group (n = 20). Guinea pigs in the form-deprived group wore a diffused (rigid glass-permeable contact lens (RGP) on one eye since one week after birth. Those in defocus group wore a -4 D RGP on one eye. The contralateral eyes were left as control. Refraction, axial length and depth of vitreous cavity were measured after 1 and 2 weeks respectively. Retina were dissected at 10-12 o'clock in the morning. The level of rhodopsin and its mRNA were observed through Western-blot and real-time PCR respectively.. There is no difference between form-deprived group, defocus group and control groups (except refraction in form-deprived group). One week later, there is no difference between the form-deprived group, the defocus group and the control groups (except refraction in form-deprived group). Two weeks later, eyes in the form-deprived group and the defocus group became myopic. Its axial length lengthened and depth of vitreous cavity appeared deep. The form-deprived groups showed an increased expression of rhodopsin and its mRNA compared to the control groups. There is no difference between the defocus group and the control groups.. Expression of rhodopsin might involve formation of form-deprived myopia, but has less influence on defocus myopia.

Topics: Animals; Guinea Pigs; Myopia; Rhodopsin; Sensory Deprivation

Three unrelated boys, ages 2, 6, and 10 years, who have congenital stationary night blindness with myopia and a Schubert-Bornschein-type electroretinogram finding, were found to show a "paradoxical" pupillary constriction in darkness. When examining room lights are turned out, the patient's pupils briskly constrict and slowly dilate. Older night blind male relatives of these boys did not show this abnormal constriction to darkness.

Topics: Adolescent; Adult; Child; Child, Preschool; Electroretinography; Female; Humans; Infant; Infant, Newborn; Male; Middle Aged; Myopia; Night Blindness; Nystagmus, Pathologic; Reflex, Pupillary; Rhodopsin; Strabismus