Abstract
Purpose: :
To analyze the proteomic changes of the lens in patients with age related cataract (AR), posterior subcapsular cataract (PS), pseudoexfoliative cataract (PSX), and cataract in Retinitis pigmentosa (RP) and to compare with a control clear lens group (CL).
Methods: :
A total of 42 lens samples were collected from each individual patients (AR= 11; PS=9; PSX=9; RP=5 and CL=8). The samples of lens were obtained after phacoemulsiphication. Immediately after their collection all samples were stored at -80ºC until the analyses. To analyze the proteomics of the lens, the samples were fractionated into two phases according to the solubility. Quantification of protein concentration was determined using EZQ fluorescence protein Quantitation kit (Invitrogen). 80 µg of soluble fraction was separated in the first dimension by isoelectric focusing, and the second dimension was carried out using SDS-PAGE in 15% polyacrylamide gels. The gel images were analyzed using Progenesis SameSpots software. Those spots with a significant fold change were automatically cut out from the gels and the corresponding proteins were identified by MALDI-TOF.
Results: :
148 spots of proteins were detected in the study, of which 54 have been identified, corresponding with 10 individual proteins and multiple isoforms. The analysis of the expression of proteins in the different types of cataracts shows a different expression profile. Plotting the significance data in a multidimensional space by principal component analysis (PCA) indicate that several protein spots enable a perfect separation between the groups (AR, PS, PSX, RP) comparing to the control group (CL). This clustering is also possible within the pathologic groups to differenciate types of cataracts. Furthermore, the MALDI-TOF MS results indicate that the proteins which are more involved in that differentiation between groups were Actin, α-crystallin B, β-crystallin B1, β-crystallin A3, β-crystallin S according to their differencial protein expression.
Conclusions: :
The results of the present study show a difference in expression pattern of the soluble proteins related with the different types of cataract. MALDI-TOF identification of several spots as the same protein suggests that the differences between groups could be due, not only to a change in the protein expression profile, but also to post-traductional- changes in the proteins.
Keywords: proteomics • crystallins • cataract