The lipofuscin component A2E selectively inhibits phagolysosomal degradation of photoreceptor phospholipid by the retinal pigment epithelium Academic Article uri icon


MeSH Major

  • Lipofuscin
  • Lysosomes
  • Phagocytosis
  • Phospholipids
  • Photoreceptor Cells
  • Pigment Epithelium of Eye
  • Pyridinium Compounds
  • Retinoids


  • 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 the circadian rhythm of RPE phagocytosis in the eye, a delay in lipid degradation would likely result in a build up of undigested material in RPE that could contribute to the development of age-related macular degeneration.

publication date

  • March 19, 2002



  • Academic Article



  • eng

PubMed Central ID

  • PMC122611

Digital Object Identifier (DOI)

  • 10.1073/pnas.052025899

PubMed ID

  • 11904436

Additional Document Info

start page

  • 3842

end page

  • 7


  • 99


  • 6