Light exposure stimulates formation of A2E oxiranes in a mouse model of Stargardt's macular degeneration

Radu, Roxana A.; Mata, Nathan L.; Bagla, Aarti; Travis, Gabriel H.

doi:10.1073/pnas.0308302101

Cited by 149 publications

(131 citation statements)

References 44 publications

Supporting

Mentioning

119

Contrasting

Order By: Relevance

“…Photoaffinity labeling of Abca4 -/-retinas ( Figure 3B in a murine model of rSTGD. Targeted disruption of the Abca4 locus in pigmented (22) and albino (23) mice (Abca4 -/-) results in a phenotype that recapitulates some rSTGD characteristics: accumulation of lipofuscin in the RPE, thicker RPE cells, slow photoreceptor degeneration, and delayed dark adaptation (22)(23)(24). To test whether rAAV2/5-mediated gene delivery results in correction of the Abca4 -/-mutant phenotype, 1-month-old mice were injected subretinally with 2 μl of rAAV2/5-CMV-Abca4 (corresponding to 1.2 × 10 9 GC) in one eye and with the same dose of rAAV2/5-CMV-EGFP in the contralateral eye.…”

Section: Resultsmentioning

confidence: 99%

Serotype-dependent packaging of large genes in adeno-associated viral vectors results in effective gene delivery in mice

Allocca¹,

Doria²,

Petrillo³

et al. 2008

J. Clin. Invest.

255

218

View full text Add to dashboard Cite

Vectors derived from adeno-associated virus (AAV) are promising for human gene therapy, including treatment for retinal blindness. One major limitation of AAVs as vectors is that AAV cargo capacity has been considered to be restricted to 4.7 kb. Here we demonstrate that vectors with an AAV5 capsid (i.e., rAAV2/5) incorporated up to 8.9 kb of genome more efficiently than 6 other serotypes tested, independent of the efficiency of the rAAV2/5 production process. Efficient packaging of the large murine Abca4 and human MYO7A and CEP290 genes, which are mutated in common blinding diseases, was obtained, suggesting that this packaging efficiency is independent of the specific sequence packaged. Expression of proteins of the appropriate size and function was observed following transduction with rAAV2/5 carrying large genes. Intraocular administration of rAAV2/5 encoding ABCA4 resulted in protein localization to rod outer segments and significant and stable morphological and functional improvement of the retina in Abca4 -/-mice. This use of rAAV2/5 may be a promising therapeutic strategy for recessive Stargardt disease, the most common form of inherited macular degeneration. The possibility of packaging large genes in AAV greatly expands the therapeutic potential of this vector system.

show abstract

Section: Resultsmentioning

confidence: 99%

Serotype-dependent packaging of large genes in adeno-associated viral vectors results in effective gene delivery in mice

Allocca¹,

Doria²,

Petrillo³

et al. 2008

J. Clin. Invest.

255

218

View full text Add to dashboard Cite

show abstract

“…Whereas chronic light exposures are difficult to quantify in human patients, experimental animal models have provided convincing evidence in support of this notion (Radu et al, 2004;Vaughan et al, 2003). Noteworthy in this regard is the recent report by Cideciyan and colleagues (2005), regarding a naturally occurring canine model of retinitis pigmentosa, in which they stated that 'modest light levels, as used in routine clinical practice, dramatically accelerated the neurodegeneration', leading those authors to call for 'a genespecific clinical trial of light reduction in human rhodopsin disease'.…”

Section: Introductionmentioning

confidence: 99%

Light-induced exacerbation of retinal degeneration in a rat model of Smith–Lemli–Opitz syndrome

Vaughan

Peachey

Richards

et al. 2006

Experimental Eye Research

View full text Add to dashboard Cite

Potentiation of retinal degeneration by intense light exposure, and its amelioration by an antioxidant, were studied in a rat model of Smith-Lemli-Opitz syndrome (SLOS), in comparison with normal (control) Sprague-Dawley rats. The SLOS model is created by treating rats with AY9944, a selective inhibitor of cholesterol synthesis at the level of 3β-hydroxysterol-Δ 7 -reductase. A subset of rats was treated with dimethylthiourea (DMTU), a synthetic antioxidant, 24 and 1 hr prior to light exposure. Half of the animals (±DMTU) were exposed to intense, constant, green light (24 hr, 1700 lx, 490-580 nm), while the others were maintained in darkness. Subsequently all animals were returned to dim cyclic light (20-40 lx, 12 hr light-12 hr dark) for 2 weeks, after which electroretinograms were recorded. One eye from each rat was taken for histological and quantitative morphometric analyses; sterol analysis was performed on retinas from contralateral eyes. HPLC analysis confirmed the accumulation of 7-dehydrocholesterol (7DHC) in retinas of AY9944-treated rats; cholesterol represented >99% of the sterol in control retinas. Histology of retinas from unexposed, AY9944-treated rats (6-week-old) was normal. In contrast, age-matched, light-exposed rats exhibited massive photoreceptor cell loss in both the superior and inferior hemispheres, and concomitant rod and cone dysfunction. The severity and geographic extent of the damage was far greater than that observed in normal albino rats exposed to the same conditions. DMTU pre-treatment largely prevented these degenerative changes. These findings indicate that the AY9944-induced rat SLOS model is hypersensitive to intense light-induced retinal damage, relative to normal rats. DMTU protection against light-induced damage implicates free radical-based oxidation in the retinal degeneration process. Furthermore, the use of green light (corresponding to the absorption maxima of rhodopsin) implicates rhodopsin in the initiation of the pathobiological mechanism. We propose that generation of cytotoxic oxysterols (by-products of 7DHC oxidation) is an integral part of retinal cell death in the SLOS rat model, which is exacerbated by intense light. Furthermore, the results predict lightdependent potentiation of retinal degeneration in SLOS patients, and the possible ameliorative effects of antioxidant therapy.

show abstract

“…This pyridinium bisretinoid pathway is more active under conditions of elevated concentrations of ATR, circumstances that likely include dysfunction of the ABCA4 (ABCR) transporter, the latter being the protein product of the Stargardt's disease gene (20). Other modulations of pyridinium bisretinoid pathway are levels of illumination (17,18,21) and the kinetics of the retinoid cycle (22).Since A2E was characterized (14, 15), several consequences of its accumulation have been reported. Because of its amphiphilic properties, A2E can exert detergent-like effects on cell membranes (23-26), perturb lysosomal function (27, 28), and mediate blue-light damage (29-31).…”

mentioning

confidence: 99%

mentioning

confidence: 99%

Isolation and characterization of a retinal pigment epithelial cell fluorophore: An all-trans -retinal dimer conjugate

Fishkin

Sparrow

Allikmets

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

148

171

View full text Add to dashboard Cite

Several lines of investigation suggest that the nondegradable fluorophores that accumulate as lipofuscin in retinal pigment epithelium (RPE) cells contribute to the etiology of macular degeneration. Despite evidence that much of this fluorescent material may originate as inadvertent products of the retinoid cycle, the enzymatic pathway by which the 11-cis-retinal chromophore of rhodopsin is generated, the only fluorophores of the RPE to be characterized as yet have been A2E and its isomers. Here, we report the isolation and structural characterization of an additional RPE lipofuscin fluorophore that originates as a condensation product of two molecules of all-trans-retinal (ATR) dimer and forms a protonated Schiff base conjugate with phosphatidylethanolamine (PE), the latter conjugate (ATR dimer-PE) having UV-visible absorbance maxima at 285 and 506 nm. ATR dimer was found to form natively in bleached rod outer segments in vitro and when rod outer segments were incubated with ATR. HPLC analysis of eyecups that included RPE and isolated neural retina from Abcr ؊͞؊ mice and RPE isolated from human donor eyes revealed the presence of a pigment with the same UV-visible absorbance and retention time as synthetic ATR dimer-PE conjugate. Evidence that ATR dimer undergoes a photooxidation process involving the addition of oxygens at double bonds as well as an aromatic demethylation also may indicate a role for this molecule, or its derivatives, in the photoreactivity of RPE lipofuscin.W hereas the lipofuscin that is amassed by most nonproliferating cells is derived from autophagy (1), lipofuscin fluorophores of the retinal pigment epithelium (RPE) originate, in large part, from photoreceptor cells (2), with Ͼ90% of the fluorescent material being generated from conjugates formed by retinoids of the visual cycle (3, 4). RPE lipofuscin fluorophores accumulate with age (5, 6), the greatest accretion is in RPE cells underlying the central retina (6), and the retinoid-derived fluorophores are particularly abundant in Stargardt's disease (7, 8), a macular degeneration of juvenile onset. Indeed, several lines of evidence indicate that the lipofuscin fluorophores that accumulate in RPE contribute to the death of these cells in some forms of macular degeneration (5, 9-13). The loss of RPE is a critical event because it is thought that it leads to bystander-like degeneration of photoreceptors that culminates in visual impairment.As yet, the only RPE lipofuscin fluorophores that have been characterized are A2E, its 13-(Z)-double-bond isomer iso-A2E, and other minor Z-isomers of A2E (14-19). These compounds are generated by hydrolysis of the phosphate ester of A2-PE, the phosphatidyl-pyridinium bisretinoid precursor that forms in rod outer segments (ROS). The synthesis of A2-PE occurs when molecules of all-trans-retinal (ATR), instead of undergoing reduction to all-trans-retinol, form conjugates with phosphatidylethanolamine (PE) through a series of random͞nonenzyme-mediated reactions (16,19). This pyridinium bisretinoid pathway is ...

show abstract

Light exposure stimulates formation of A2E oxiranes in a mouse model of Stargardt's macular degeneration

Cited by 149 publications

References 44 publications

Serotype-dependent packaging of large genes in adeno-associated viral vectors results in effective gene delivery in mice

Serotype-dependent packaging of large genes in adeno-associated viral vectors results in effective gene delivery in mice

Light-induced exacerbation of retinal degeneration in a rat model of Smith–Lemli–Opitz syndrome

Isolation and characterization of a retinal pigment epithelial cell fluorophore: An all-trans -retinal dimer conjugate

Contact Info

Product

Resources

About