This project will develop methods to reduce the amounts of N-retinyledene-N-retinylethanolamine (A2E) in the retinal pigment epithelia (RPE). The excessive accumulation of this lipofuscin component contributes to the onset of age-related macular degeneration (ARMD). Thus, any methods that can remove A2E from the RPE will be useful in developing potential therapies to treat this disease. To test the efficiency of various methods to remove A2E from cultured RPE cells, we will use a fluorescence plate reader and fluorescence microscopy to measure both the intracellular concentration and the subcellular location of A2E. Initial results using an in vitro system have already identified several drugs which are capable of removing A2E from phospholipid membranes. Subsequent work will focus on delivering these drugs to the Iysosomes of RPE, the site of A2E subcellular accumulation. Recent evidence suggests that A2E impairs the ability of RPE to degrade phospholipids derived from phagocytosed outer segment. Each day, the RPE is presented with shed outer segment particles, and must complete the digestion of these particles before the next day. Any delay in the digestion of the OSphospholipids, which comprises more than half of the total OS mass, will result in the gradual accumulation of these phospholipids. Once the development of methods that can remove A2E is achieved, the effectiveness of these systems in restoring the ability of A2E-treated RPE to degrade OS phospholipids will be examined. A flourescence-based lipid degradation assay has already been developed in this lab.
