Abstract
Purpose: :
To identify RPE proteome changes associated with aging and development of age-related macular degeneration.
Methods: :
Human RPE proteins were extracted from 6 young (<55), 6 old (>65) and 5 AMD eyes. RPE proteins were focused using non-liner (pH 3-10) 7.7cm IEF strips. Proteins were further separated in the second dimension on 4-12% Bis-Tris gels. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) was used to identify spots. For each group, common spots (>2/3 gels) were identified and intra-group variations were calculated. Comparison of the RPE proteomes from young and old donors with AMD eyes allowed us to identify differentially expressed RPE proteins by aging and AMD. Western blotting and immunohistochemistry was used to validate the results.
Results: :
67.8 ± 10.8% of the RPE proteins were common in young donors (age: 45 ± 15) donor eyes. Aging (age: 76 ± 9) increased the variation in protein expression decreasing the number of common proteins down to 50.4 ± 12.3 %. In AMD eyes (age: 89 ± 4) 67.2 ± 18.3% of the proteome was common. Conversion from aged to AMD involved disappearance of 42 common spots and appearance of 23 new spots.
Conclusions: :
Aging and AMD is goes along with specific RPE proteome changes.Diversified expression of RPE proteins by aging can be a reflection of adaptive efforts of RPE to cumulative celluar stressors. Identification of AMD-specific RPE proteome changes will yield biomarkers to aid early diagnosis and monitoring of AMD.
Keywords: proteomics • age-related macular degeneration • retinal pigment epithelium