Abstract
Purpose: :
The R120G mutation of αB-crystallin is known to cause desmin-related myopathy but the mechanisms underlying the formation of cataract are not clearly established. We speculate that alteration of the protein-protein interaction between R120G αB-crystallin and lens intermediate filament proteins is one of the mechanisms for the congenital cataract.
Methods: :
Protein-protein interaction was determined by confocal fluorescence resonance energy transfer (FRET) microscopy using green fluorescence protein (GFP) as the donor and red fluorescence protein (RFP) as the acceptor. Lens intermediate filament (IF) protein gene (vimentin, filensin or CP49) was fused into GFP vector and αB-crystallin (WT or R120G mutant) gene was fused into the RFP vector. The donor-acceptor plasmid pairs of IF-GFP and αB-RFP were co-transfected into HeLa cells. After incubation, confocal fluorescence images of the transfected cells were taken. Protein-protein interaction was evaluated by FRET between the donor and the acceptor.
Results: :
The confocal fluorescence images showed that the R120G αB-crystallin expression contained large amounts of protein aggregates with either vimentin, or filensin, or CP49 protein. FRET analyses indicated that R120G αB-crystallin had a significantly greater protein-protein interaction than WT αB-crystallin.
Keywords: crystallins • cytoskeleton • protein structure/function