Abstract
Purpose: :
Age is a primary risk factor for age-related macular degeneration (AMD). We used proteomics to identify changes in the human retinal pigment epithelium (RPE) associated with normal aging. This analysis will provide a basis for distinguishing normal from pathologic aging.
Methods: :
The RPE was harvested from thirty-eight human donor globes obtained from the Minnesota Lions Eye Bank. Donor ages ranged from 34 to 86 years. For all donor eyes, there was no evidence or history of retinal disease. Proteins were separated using two-dimensional gel electrophoresis and visualized with Flamingo Fluorescent Gel Stain. Relative protein content was determined for each spot using densitometric analysis. Multiple regression analysis was used to determine patterns of change in protein content with age. Spots fitting a linear or quadratic model were identified by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF). Protein identification was verified by sequencing at least one or more peptides from the spot.
Results: :
A total of 240 spots were analyzed. Seven spots increased and 5 spots decreased with age. For proteins identified to date, an age-related increase in the lysosomal protease cathepsin D was observed. Increased content of carbonic anhydrase 1 and selenium-binding protein 1, proteins involved in regulating pH and intra-golgi transport, respectively, were also associated with age.
Conclusions: :
Only a small number of protein spots demonstrated a significant age-related change in content in the human RPE. Future studies that find these proteins in connection to age-related retinal disease such as AMD should be interpreted in light of these findings that their content varies with age.
Keywords: aging • retinal pigment epithelium • proteomics