Abstract
Abstract: :
Purpose: To understand the mechanisms that lead to cataract formation in the alphaA-crystallin gene knockout mouse. Methods: Inclusion bodies that form in the knockout mouse lens were isolated by sucrose density step gradient ultracentrifugation. Two-dimensional gel electrophoresis was used to analyze the proteins in the inclusion bodies. Soluble and insoluble lens proteins were obtained from alphaA knockout mice and compared with those from wild type mice using gel filtration chromatography and SDS-PAGE. Results: Consistent with previous findings, the majority of proteins in the inclusion bodies is alphaB-crystallin. However, a significant amount of gamma-crystallin (∼10%) was also found in the inclusion bodies. Analysis of lens soluble proteins showed that the age-dependent conversion of the gamma-crystallin to the insoluble form was significantly higher in the knockout mice than in age-matched wild type mice. No differences were found in the distribution of beta-crystallins. Conclusions: In addition to the formation of inclusion bodies, disruption of the alphaA gene causes acceleration in the redistribution of gamma-crystallin from the soluble fraction to the insoluble fraction. It is also conceivable that the gamma-crystallins are involved in the formation of the inclusion bodies in the knockout lens, possibly by providing nucleation centers.
Keywords: 378 crystallins • 338 cataract • 343 chaperones