Tracking pathology with proteomics: Identification of in vivo degradation products of alpha B-crystallin

Soemmerring's ring is one form of "after cataract" that can occur following cataract surgery. The ring structure is formed by adherence of the anterio r lens capsule to the posterior lens capsule. Epithelial cells remaining af ter surgery differentiate into lens fiber cells but the resulting tissue ma ss does not remain transparent. The protein in normal lens and in Soemmerri ng's rings from four individuals was analyzed using two-dimensional (2-D) g el electrophoresis, matrix assisted laser desorption/ionization-time of-fli ght-mass spectrometry (MALDI-TOF-MS) and image analysis with Phoretix softw are. The 2-D protein patterns of the Soemmerring's rings were generally sim ilar to that of cortical fiber cells of normal human lens with some notable exceptions. Several posttranslationally modified forms of alpha beta-cryst allin((1-175)) were identified. Two degradation products, alpha beta-crysta llin((1-170)) and alpha beta-crystallin((1-174)), each make up 9.5-27% of t he total alpha beta-crystallin in the Soemmerring's rings and less than 1% in the normal lenses. Other modified forms of alpha beta-crystallin are abe rrant in the fiber cells of the Soemmerring rings relative to normal lens.