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Vincent M Monnier, Benlian Wang, Xingjun Fan; The Comparative Lens non-crystallin Disulfidome of LEGSKO Mouse and Human Cataract. Invest. Ophthalmol. Vis. Sci. 2017;58(8):3184.
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Glutathione (GSH) is the most abundant anti-oxidative compound found in the lens. In age-related nuclear cataract (ARNC) GSH levels are impaired and accompanied with increased oxidation, protein disulfide formation and protein cross-link. We recently found that the lens crystallin disulfidome was evolutionarily conserved in human and glutathione depleted mouse (LEGSKO) cataracts and that it could be mimicked by oxidation in vitro<!--[endif]---->(Fan et al. 2015). We have now used the same approach to determine all the disulfide-forming non-crystallin proteins identified by ICAT proteomics. <!--![endif]---->
Young, aged normal and level II to V (based on LOCS III) human cataract lenses were collected and the cysteine residues involving in disulfide formation was mapped by isotope-coded affinity-tag (ICAT) profiling method, and was compared with LEGSKO cataract mouse lenses as well as the in vitro model of crystallin aggregation and opacification by H2O2 oxidation. Only non-crystallin proteins were reported in this study.
74, 50, and 54 disulfide forming proteins were identified in the human and mouse cataracts and the in vitro oxidation model, respectively. 17 were common to all three groups. 38-45% of identified disulfide forming proteins are those with catalytic activity, and 24-30% of disulfide forming proteins are lens structural proteins. Enzymes with oxidized cysteine at critical sites include GAPDH (hGAPDH, Cys247), glutathione synthase (hGSS, Cys 294), aldehyde dehydrogenase (hALDH1A1, Cys126 and Cys186), sorbitol dehydrogenase (hSORD, Cys140, Cys165 and Cys179), and PARK7 (hPARK7, Cys46 and Cys53). Extensive oxidation was also present in lens specific intermediated filament proteins, such as BFSP1&2 (hBFSP1&2, cys167, cys65 and Cys326), vimentin (mVim, cys328), cytokeratins, as well as microfilament and microtubule filament proteins, such as tubulin and actins.
While the biological impact of these modifications for lens physiology remains to be determined, many of these oxidation sites have already been associated with either impaired metabolism or cytoskeletal architecture, strongly suggesting that they have a pathogenic role in cataractogenesis.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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