9-cis-retinal and Disease-Models--Animal

Fatty acid transport protein 4 (FATP4), a transmembrane protein in the endoplasmic reticulum (ER), is a recently identified negative regulator of the ER-associated retinal pigment epithelium (RPE)65 isomerase necessary for recycling 11-

Topics: Animals; cis-trans-Isomerases; Cone Opsins; Disease Models, Animal; Diterpenes; Fatty Acid Transport Proteins; Humans; Leber Congenital Amaurosis; Mice; Mice, Knockout; Mutation; Retina; Retinaldehyde; Vision, Ocular

The retinoid (visual) cycle consists of a series of biochemical reactions needed to regenerate the visual chromophore 11-

Topics: Acyltransferases; Administration, Oral; Animals; Blindness; Chitosan; Cone Opsins; Disease Models, Animal; Diterpenes; Dogs; Dose-Response Relationship, Drug; Electroretinography; Female; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Opsins; Photoreceptor Cells, Vertebrate; Retinal Pigment Epithelium; Retinaldehyde; Rod Opsins; Tomography, Optical Coherence

Rhodopsin homeostasis is tightly coupled to rod photoreceptor cell survival and vision. Mutations resulting in the misfolding of rhodopsin can lead to autosomal dominant retinitis pigmentosa (adRP), a progressive retinal degeneration that currently is untreatable. Using a cell-based high-throughput screen (HTS) to identify small molecules that can stabilize the P23H-opsin mutant, which causes most cases of adRP, we identified a novel pharmacological chaperone of rod photoreceptor opsin, YC-001. As a non-retinoid molecule, YC-001 demonstrates micromolar potency and efficacy greater than 9-cis-retinal with lower cytotoxicity. YC-001 binds to bovine rod opsin with an EC

Topics: Alcohol Oxidoreductases; Animals; ATP-Binding Cassette Transporters; Cell Line, Tumor; Disease Models, Animal; Diterpenes; Female; HEK293 Cells; High-Throughput Screening Assays; Humans; Light; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Mutation; Neuroprotective Agents; NIH 3T3 Cells; Protein Folding; Protein Transport; Retinal Degeneration; Retinal Rod Photoreceptor Cells; Retinaldehyde; Rhodopsin; Thiophenes; Treatment Outcome

Investigate whether retinas of mice with impaired retinal cycles exposed to light or kept in the dark tolerate prolonged high-dose administration of QLT091001, which contains as an active ingredient, the 9-cis-retinal precursor, 9-cis-retinyl acetate.. Four- to six-week-old Lrat(-/-) and Rpe65(-/-) mice (n = 126) as well as crossbred Gnat1(-/-) mice lacking rod phototransduction (n = 110) were gavaged weekly for 6 months with 50 mg/kg QLT091001, either after being kept in the dark or after light bleaching for 30 min/wk followed by maintenance in a 12-hour light ≤ 10 lux)/12-hour dark cycle. Retinal health was monitored by spectral-domain optical coherent tomography (SD-OCT) and scanning laser ophthalmoscopy (SLO) every other month and histological, biochemical, and visual functional analyses were performed at the end of the experiment. Two-photon microscopy (TPM) was used to observe retinoid-containing retinosome structures in the RPE.. Retinal thickness and morphology examined by SD-OCT were well maintained in all strains treated with QLT091001. No significant increases of fundus autofluorescence were detected by SLO imaging of any strain. Accumulation of all-trans-retinyl esters varied with genetic background, types of administered compounds and lighting conditions but retinal health was not compromised. TPM imaging clearly revealed maintenance of retinosomes in the RPE of all mouse strains tested.. Retinas of Lrat(-/-), Rpe65(-/-), and crossbred Gnat1(-/-) mice tolerated prolonged high-dose QLT091001 treatment well.

Topics: Animals; Dark Adaptation; Disease Models, Animal; Diterpenes; Electroretinography; Female; Isomerism; Male; Mice; Mice, Inbred C57BL; Pigment Epithelium of Eye; Retinal Cone Photoreceptor Cells; Retinaldehyde; Tomography, Optical Coherence; Vision Disorders

To design and develop a drug-delivery system containing a combination of poly(D,L-lactide-co-glycolide) (PLGA) microparticles and alginate hydrogel for sustained release of retinoids to treat retinal blinding diseases that result from an inadequate supply of retinol and generation of 11-cis-retinal.. To study drug release in vivo, either the drug-loaded microparticle-hydrogel combination was injected subcutaneously or drug-loaded microparticles were injected intravitreally into Lrat(-/-) mice. Orally administered 9-cis-retinoids were used for comparison and drug concentrations in plasma were determined by HPLC. Electroretinography (ERG) and both chemical and histologic analyses were used to evaluate drug effects on visual function and morphology.. Lrat(-/-) mice demonstrated sustained drug release from the microparticle/hydrogel combination that lasted 4 weeks after subcutaneous injection. Drug concentrations in plasma of the control group treated with the same oral dose rose to higher levels for 6-7 hours but then dropped markedly by 24 hours. Significantly increased ERG responses and a markedly improved retinal pigmented epithelium (RPE)-rod outer segment (ROS) interface were observed after subcutaneous injection of the drug-loaded delivery combination. Intravitreal injection of just 2% of the systemic dose of drug-loaded microparticles provided comparable therapeutic efficacy.. Sustained release of therapeutic levels of 9-cis-retinoids was achieved in Lrat(-/-) mice by subcutaneous injection in a microparticle/hydrogel drug-delivery system. Both subcutaneous and intravitreal injections of drug-loaded microparticles into Lrat(-/-) mice improved visual function and retinal structure.

Topics: Acyltransferases; Administration, Oral; Alginates; Animals; Blindness; Delayed-Action Preparations; Disease Models, Animal; Diterpenes; Drug Delivery Systems; Drug Therapy, Combination; Electroretinography; Female; Glucuronic Acid; Hexuronic Acids; Humans; Hydrogel, Polyethylene Glycol Dimethacrylate; Injections, Subcutaneous; Intravitreal Injections; Lactic Acid; Male; Mice; Mice, Mutant Strains; Microspheres; Polyglycolic Acid; Polylactic Acid-Polyglycolic Acid Copolymer; Retinaldehyde; Retinoids

To determine the efficacy of intravitreal administration of 9-cis-retinal in restoring visual function in Rpe65-mutant dogs.. Intravitreal injection of 9-cis-retinal was administered in 1 eye of 7 Rpe65-/- dogs at a range of ages. Electroretinogram analysis and testing of visual performance was used to evaluate outcomes after a single injection and in 2 dogs after a second injection in the same eye.. In 5 of 7 injected dogs, 9-cis-retinal injection resulted in increased rod electroretinogram responses and improved functional vision. Three injected dogs exhibited increased 33-Hz flicker amplitudes characteristic of cone-mediated responses. Electroretinogram improvement was no longer evident by week 10 postinjection in 1 dog monitored over time. A second injection of 9-cis-retinal was performed in the same eye of 2 of the 7 dogs and also resulted in rescue of visual function.. Our findings establish that 9-cis-retinoid therapy can restore visual function in a canine model of human disease resulting from RPE65 mutations.. These positive proof-of-principle results provide support for the development of intravitreal devices for sustained delivery of 9-cis-retinal as a therapy for conditions resulting from failure of the visual cycle.

Topics: Animals; Carrier Proteins; Dark Adaptation; Disease Models, Animal; Diterpenes; Dogs; Electroretinography; Eye Proteins; Female; Intravitreal Injections; Isomerism; Leber Congenital Amaurosis; Male; Mutation; Photoreceptor Cells, Vertebrate; Retinaldehyde; Retreatment; Vision, Ocular; Visual Acuity

Topics: Animals; Disease Models, Animal; Diterpenes; Dogs; Electroretinography; Eye Proteins; Intravitreal Injections; Leber Congenital Amaurosis; Mutation; Retinaldehyde; Vision, Ocular; Visual Acuity

To assess changes in rod and cone visual functions in a mouse model of Fundus albipunctatus with disrupted 11-cis-retinol dehydrogenase (RDH) genes after pharmacologic treatment with an artificial retinal chromophore.. Retinoid levels and photoreceptor functions of Rdh5-/-Rdh11-/- mice at a variety of light intensities were analyzed with normal-phase HPLC and ERG techniques. Production of 11-cis-retinal, the visual pigment chromophore, was suppressed with a potent inhibitor of the retinoid cycle, all-trans-retinylamine (Ret-NH2). The chromophore was replaced by a functional geometric isomer, 9-cis-retinal, delivered by oral gavage.. Aberrant cone responses were detected in 12-month-old Rdh5-/-Rdh11-/- mice raised in a 12-hour light/12-hour dark cycle. This cone defect was exacerbated in conditions of low levels of 11-cis-retinal. Administration of 9-cis-retinal increased the rate of dark adaptation and improved cone function in Rdh5-/-Rdh11-/- mice.. Disruption of 11-cis-RDHs causes a slowly developing cone dystrophy caused by inefficient cone pigment regeneration. Rod and cone visual function improved significantly in the mouse model of F. albipunctatus after treatment with 9-cis-retinal, suggesting a potential approach to slow the progression of cone dystrophy in affected humans.

Topics: Animals; Chromatography, High Pressure Liquid; Dark Adaptation; Disease Models, Animal; Diterpenes; Electroretinography; Isomerism; Mice; Mice, Knockout; Oxidoreductases; Photoreceptor Cells, Vertebrate; Pigment Epithelium of Eye; Retinal Degeneration; Retinal Dehydrogenase; Retinaldehyde; Retinoids

The visual process is initiated by the photoisomerization of 11-cis-retinal to all-trans-retinal. For sustained vision the 11-cis-chromophore must be regenerated from all-trans-retinal. This requires RPE65, a dominant retinal pigment epithelium protein. Disruption of the RPE65 gene results in massive accumulation of all-trans-retinyl esters in the retinal pigment epithelium, lack of 11-cis-retinal and therefore rhodopsin, and ultimately blindness. We reported previously (Van Hooser, J. P., Aleman, T. S., He, Y. G., Cideciyan, A. V., Kuksa, V., Pittler, S. J., Stone, E. M., Jacobson, S. G., and Palczewski, K. (2000) Proc. Natl. Acad. Sci. U. S. A. 97, 8623-8628) that in Rpe65-/- mice, oral administration of 9-cis-retinal generated isorhodopsin, a rod photopigment, and restored light sensitivity to the electroretinogram. Here, we provide evidence that early intervention by 9-cis-retinal administration significantly attenuated retinal ester accumulation and supported rod retinal function for more than 6 months post-treatment. In single cell recordings rod light sensitivity was shown to be a function of the amount of regenerated isorhodopsin; high doses restored rod responses with normal sensitivity and kinetics. Highly attenuated residual rod function was observed in untreated Rpe65-/- mice. This rod function is likely a consequence of low efficiency production of 11-cis-retinal by photo-conversion of all-trans-retinal in the retina as demonstrated by retinoid analysis. These studies show that pharmacological intervention produces long lasting preservation of visual function in dark-reared Rpe65-/- mice and may be a useful therapeutic strategy in recovering vision in humans diagnosed with Leber congenital amaurosis caused by mutations in the RPE65 gene, an inherited group of early onset blinding and retinal degenerations.

Topics: Animals; Blindness; Carrier Proteins; cis-trans-Isomerases; Disease Models, Animal; Diterpenes; Electroretinography; Eye Proteins; Mice; Microscopy, Electron; Optic Atrophy, Hereditary, Leber; Pigment Epithelium of Eye; Proteins; Retinaldehyde

Mutations in the retinal pigment epithelium gene encoding RPE65 are a cause of the incurable early-onset recessive human retinal degenerations known as Leber congenital amaurosis. Rpe65-deficient mice, a model of Leber congenital amaurosis, have no rod photopigment and severely impaired rod physiology. We analyzed retinoid flow in this model and then intervened by using oral 9-cis-retinal, attempting to bypass the biochemical block caused by the genetic abnormality. Within 48 h, there was formation of rod photopigment and dramatic improvement in rod physiology, thus demonstrating that mechanism-based pharmacological intervention has the potential to restore vision in otherwise incurable genetic retinal degenerations.

Topics: Administration, Oral; Animals; Blindness; Carrier Proteins; Child; cis-trans-Isomerases; Disease Models, Animal; Diterpenes; Eye Proteins; Female; Humans; Male; Mice; Mice, Knockout; Pigment Epithelium of Eye; Proteins; Retinal Degeneration; Retinal Rod Photoreceptor Cells; Retinaldehyde; Retinoids; Time Factors