The lipofuscin fluorophore A2E mediates blue light-induced damage to retinal pigmented epithelial cells

Invest Ophthalmol Vis Sci. 2000 Jun;41(7):1981-9.


Purpose: To determine whether the lipofuscin fluorophore A2E participates in blue light-induced damage to retinal pigmented epithelial (RPE) cells.

Methods: Human RPE cells (ARPE-19) accumulated A2E from 10, 50, and 100 microM concentrations in media, the levels of internalized A2E ranging from less than 5 to 64 ng/10(5) cells, as assayed by quantitative high-performance liquid chromatography (HPLC). Restricted zones (0.5-mm diameter spots) of confluent cultures were subsequently exposed to 480 +/- 20-nm (blue) or 545 +/- 1-nm (green) light for 15 to 60 seconds. Phototoxicity was quantified at various periods after exposure by fluorescence staining of the nuclei of membrane-compromised cells, by TdT-dUTP terminal nick-end labeling (TUNEL) of apoptotic cells and by Annexin V labeling for phosphatidylserine exposure.

Results: Nonviable cells were located in blue light- exposed zones of A2E-containing RPE cells, whereas cells situated outside the illuminated areas remained viable. As shown by fluorescence labeling of the nuclei of membrane-damaged cells and by the presence of TUNEL-positive cells, the numbers of nonviable cells increased with exposure duration and as a function of the concentration of A2E used to load the cells before illumination. The numbers of blue light-induced TUNEL-positive cells also increased in advance of the increase in labeling of membrane-compromised cells, a finding that, together with Annexin V labeling, indicates an apoptotic form of cell death. Conversely, blue light- exposed RPE cells that did not contain A2E remained viable. In addition, illumination with green light resulted in the appearance of substantially fewer nonviable cells.

Conclusions: These studies implicate A2E as an initiator of blue light-induced apoptosis of RPE cells.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Annexin A5 / metabolism
  • Apoptosis / radiation effects*
  • Cells, Cultured
  • Chromatography, High Pressure Liquid
  • DNA / radiation effects
  • DNA Damage
  • Humans
  • Light
  • Lipofuscin*
  • Microscopy, Fluorescence
  • Pigment Epithelium of Eye / metabolism*
  • Pigment Epithelium of Eye / pathology
  • Pigment Epithelium of Eye / radiation effects*
  • Pyridinium Compounds / metabolism*
  • Retinal Pigments
  • Retinoids / metabolism*


  • Annexin A5
  • Lipofuscin
  • Pyridinium Compounds
  • Retinal Pigments
  • Retinoids
  • DNA