Mechanism of cataract formation in alphaA-crystallin Y118D mutation.

Abstract

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 alphaA-crystallin gene.

METHODS:

The physicochemical properties of alpha-crystallin obtained from mouse lenses with the Y118D mutation as well as a recombinant Y118D alphaA-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 alphaA-Y118D displayed higher molecular mass distribution than the wild-type. Circular dichroism spectra indicated changes in the secondary structures of alphaA-Y118D. The alphaA-Y118D protein prevented nonspecific protein aggregation more effectively than wild-type alphaA-crystallin. The gel filtration and 2D gel electrophoresis analysis showed a significant reduction of Y118D mutant protein in comparison with wild-type alphaA protein of heterozygous mutant lenses. Quantitative RT-PCR results confirmed a decrease in alphaA and alphaB transcripts in the homozygous mutant alpha A(Y118D/Y118D) lenses.

CONCLUSIONS:

The alphaA-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 alphaA-crystallin, leading to a reduction in total chaperone capacity needed for maintaining lens transparency.

• Authors: Qingling Huang, Linlin Ding, Kim B Phan, Catherine Cheng, Chun-hong Xia, Xiaohua Gong, Joseph Horwitz
• Journal: Investigative ophthalmology & visual science (Invest Ophthalmol Vis Sci) Vol. 50 Issue 6 Pg. 2919-26 (Jun 2009) ISSN: 1552-5783 [Electronic] United States
• PMID: 19151380 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)

Chemical References

• alpha-Crystallin A Chain

Topics

• Animals
• Cataract (genetics)
• Chromatography, Gel
• Circular Dichroism
• Electrophoresis, Gel, Two-Dimensional
• Lens, Crystalline
• Light
• Mice
• Point Mutation
• Reverse Transcriptase Polymerase Chain Reaction
• Scattering, Radiation
• alpha-Crystallin A Chain (genetics)