Mechanism of Cataract Formation in alpha A-crystallin Y118D Mutation

作者：Huang Qingling; Ding Linlin; Phan Kim B; Cheng Catherine; Xia Chun hong; Gong Xiaohua; Horwitz Joseph^*

来源：Investigative Ophthalmology & Visual Science, 2009, 50(6): 2919-2926.

DOI：10.1167/iovs.08-3070

PURPOSE. The aim of this study was to elucidate the molecular mechanisms that lead to a dominant nuclear cataract in a mouse harboring the Y118D mutation in the alpha A- crystallin gene.
METHODS. The physicochemical properties of alpha-crystallin obtained from mouse lenses with the Y118D mutation as well as a recombinant Y118D alpha A-crystallin were studied using gel filtration, two-dimensional (2D) gel electrophoresis, multi-angle light scattering, circular dichroism, fluorescence, and chaperone activities.
RESULTS. Both native alpha-crystallin from mutant lens and recombinant alpha A-Y118D displayed higher molecular mass distribution than the wild-type. Circular dichroism spectra indicated changes in the secondary structures of alpha A-Y118D. The alpha A-Y118D protein prevented nonspecific protein aggregation more effectively than wild-type alpha A-crystallin. The gel filtration and 2D gel electrophoresis analysis showed a significant reduction of Y118D mutant protein in comparison with wild-type alpha A protein of heterozygous mutant lenses. Quantitative RT-PCR results confirmed a decrease in alpha A and alpha B transcripts in the homozygous mutant alpha A( Y118D/Y118D) lenses.
CONCLUSIONS. The alpha A-Y118D mutant protein itself displays an increased chaperone-like activity. However, the dominant nuclear cataract is associated with a significant decrease in the amount of alpha A-crystallin, leading to a reduction in total chaperone capacity needed for maintaining lens transparency. ( Invest Ophthalmol Vis Sci. 2009; 50: 2919-2926) DOI: 10.1167/iovs.08-3070

• 出版日期2009-6