Abstract
Purpose: :
The purpose was to elucidate temporal changes in crystallin- and gene- expression profiles of a transgenic mouse model with deamidation of αA at N101 to D (αAN101D) compared to wild type αA transgenic mice (WT).
Methods: :
Because relative to 7-month old WT mice, the same aged transgenic mice with αAN101D trans gene showed cortical cataract development (J. Biol. Chem. 286:11579-11592, 2011), the crystallin- and gene expression profiles of αAN101D and WT mice were compared. The water soluble (WS)- and water insoluble (WI)-proteins from lenses of 4- and 7-months old mice were fractionated by two-dimensional difference gel electrophoretic (2D-DIGE) method and crystallin spots identified by mass spectrometric method. The differential gene expression in lenses of 2- and 4-months old αAN101D- and WT-mice were compared by whole transcriptome analysis (RNA-seq) followed by analysis using a systems biology software (Ingenuity Pathway Analysis).
Results: :
The major difference in the crystallin profiles was that lenses from 4- and 7-months old αAN101D mice exhibited a greater number of crystallin fragments (Mr < 20 kDa) in both WS- and WI-proteins relative to the same aged WT mice. The mass spectrometric analysis showed that the majority of crystallin fragments were derived from αA- and αB-crystallins. Whole transcryptome analysis identified several genes that were either up- or down-regulated in 2- and 4-months old αAN101D mice relative to same aged WT mice. Most notable result was the up-regulation of transcripts of apoptotic genes and a Ca+2-binding protein and down-regulation of transcripts of cytoskeletal proteins in αAN101D mice relative to WT mice.
Conclusions: :
Relative to WT-mice, increased truncations of αA- and αB-crystallins occurred in αAN101D mice prior to (at 4-months) and during cortical cataract development (at 7-months). Changes in mRNA profile suggest that major reorganization of cytoskeletal proteins and possible apoptosis in lenses of αAN101D mice that might contribute to the development of cortical cataract.
Keywords: crystallins • transgenics/knock-outs • cataract