Purpose   To compare protein expressions and modifications between normal and age-related cataract lenses using a proteomic approach.

Methods Total proteins in pooled normal and cataract lenses were separated by two-dimensional (2D) gel electrophoresis. Proteins in the gel were visualized by silver stain, and the densities of each spot were quantified with a gel analysis software. These spots that showed > 3-fold differences between control and cataract lenses were in-gel-digested and identified by MALDI-TOF-MS.

Results   The densities of 84 spots in the two-dimensional gel electrophoresis profile showed cataract-related differences.  Among these spots, 9 spots were only detected in normal lenses and 1 spots was detected only in age-related cataract lenses.  The densities of 7 spots were >3 fold higher in cataract lenses than in normal lenses.  In contrast, the densities of 3 other spots >3 fold higher in normal lenses than in cataract lenses.  The identities of 5 spots that showed cataract-related changes were determined by MALDI-TOF-MS.  These spots were derived from alpha A-crystallin, beta A4-crystallin ,beta A3-crystallin , beta-B1-crystallin and beta B2-crystallin.

Conclusions The protein composition in lens was significantly different between the normal lens and age-related cataract. The identified proteins could be a potential biomarker for age-related cataract development and may play a role in the mechanisms of cataract.