Lipofuscin accumulates in the aging retinal pigment epithelium (RPE). It is identified by its fluorescence; however, lipofuscin is a complex mixture, and fluorescence is not specific enough to identify its individual components. Utilizing matrix-assisted laser desorption-ionization imaging, we have recently determined the spatial distribution of lipofuscin components across the RPE. One of the most abundant signals was that of the bis -retinoid A2E, a byproduct of the visual cycle. To better understand the accumulation of A2E, we studied wild-type ( wt ), Rpe65 −/− , and Abca4 −/− mice. A2E was not found in Rpe65 −/− animals. In wt animals, A2E was most abundant in the center of the RPE and diminished toward the periphery. In contrast, the A2E signal was more intense and uniformly distributed in Abca4 −/− mice. The oxidized forms of A2E were also spatially localized. Furthermore, a highly sensitive liquid chromatography–tandem mass spectrometry (LC-MS/MS) method was utilized to quantitate A2E. A2E oxidation sites were determined both in organic extracts and directly from the tissue. The ability to image a specific retinoid and its modified products from fresh tissue suggests wide applicability in the research and potential treatments of retinal degeneration.
Mendeley saves you time finding and organizing research
Choose a citation style from the tabs below