The lipofuscin component A2E selectively inhibits phagolysosomal degradation of photoreceptor phospholipid by the retinal pigment epithelium.

ABSTRACT: Daily phagocytosis of spent photoreceptor outer segments is a critical maintenance function performed by the retinal pigment epithelium (RPE) to preserve vision. Aging RPE accumulates lipofuscin, which includes N-retinylidene-N-retinylethanolamine (A2E) as the major autofluorescent component. We studied the effect of physiological levels of A2E in RPE cultures on their ability to phagocytose outer segments. A2E localized to lysosomes in cultured RPE as well as in human RPE in situ. A2E-loaded RPE cells in culture bound and internalized identical numbers of outer segments as control RPE indicating that A2E does not alter early steps of phagocytosis. A2E-loaded RPE degraded outer segment proteins efficiently but, strikingly, failed to completely digest phospholipids within 24 h. Because of t

SUBMITTER: Finnemann SC 

PROVIDER: S-EPMC122611 | biostudies-literature | 2002 Mar

REPOSITORIES: biostudies-literature