The all-trans-retinal dimer series of lipofuscin pigments in retinal pigment epithelial cells in a recessive Star gardt disease model

The bis-retinoid pigments that accumulate in retinal pigment epithelial cells as lipofuscin are associated with inherited and age-related retinal disease. In addition to A2E and related cis isomers, we previously showed that condensation of two molecules of all-trans-retinal leads to the formation o...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2007-12, Vol.104 (49), p.19273
Main Authors: Kim, So R, Jang, Young P, Jockusch, Steffen, Fishkin, Nathan E, Turro, Nicholas J, Sparrow, Janet R
Format: Article
Language:English
Subjects:
Amino acids
Cells
Macular degeneration
Mass spectrometry
Ophthalmology
Pigments
Retina
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Summary:The bis-retinoid pigments that accumulate in retinal pigment epithelial cells as lipofuscin are associated with inherited and age-related retinal disease. In addition to A2E and related cis isomers, we previously showed that condensation of two molecules of all-trans-retinal leads to the formation of a protonated Schiff base conjugate, all-trans-retinal dimer-phosphatidylethanolamine. Here we report the characterization of the related pigments, all-trans-retinal dimer-ethanolamine and unconjugated all-trans-retinal dimer, in human and mouse retinal pigment epithelium. In eyecups of Abcr... mice, a model of recessive Stargardt macular degeneration, all-trans-retinal dimer-phosphatidylethanolamine was increased relative to wild type and was more abundant than A2E. Total pigment of the all-trans-retinal dimer series (sum of all-trans-retinal dimer-phosphatidylethanolamine, all-trans-retinal dimer-ethanolamine, and all-trans-retinal dimer) increased with age in Abcr... mice and was modulated by amino acid variants in Rpe65. In in vitro assays, enzyme-mediated hydrolysis of all-trans-retinal dimer-phosphatidylethanolamine generated all-trans-retinal dimer-ethanolamine, and protonation/deprotonation of the Schiff base nitrogen of all-trans-retinal dimer-ethanolamine was pH-dependent. Unconjugated all-trans-retinal dimer was a more efficient generator of singlet oxygen than A2E, and the all-trans-retinal dimer series was more reactive with singlet oxygen than was A2E. By analyzing chromatographic properties and UV-visible spectra together with mass spectrometry, mono- and bis-oxygenated all-trans-retinal dimer photoproducts were detected in Abcr... mice. The latter findings are significant to an understanding of the adverse effects of retinal pigment epithelial cell lipofuscin. (ProQuest: ... denotes formulae/symbols omitted.)
ISSN:0027-8424
1091-6490