Age-related nuclear (ARN) cataract is a major cause of world blindness. There has been a revolution in our understanding of ARN cataract in the past 1-2 years. Up until that time, essentially all that was known was that ARN cataract is associated with profound oxidation and that this is accompanied by insolubilisation, coloration and cross-linking of lens proteins. It was unclear why such massive oxidative changes occurred in the nuclei of these lenses. Recent advances suggest that ARN cataract develops as a direct result of changes in the lens that occur with age. These include the discovery of the probable reason for lens coloration and the biochemical/physical basis that may allow oxidation in the centre of the lens to proceed; resulting ultimately in cataract. Briefly, a barrier to the movement of the antioxidant, glutathione (GSH) from its site of synthesis or reduction in the cortex, into the lens nucleus, forms in older individuals. Thus the nucleus of the older normal human lens becomes susceptible to oxidative stress. In addition, human lens UV filter compounds are intrinsically unstable and undergo deamination to form reactive ketones. Once the barrier forms, these have time to breakdown and then readily react with lens crystallins. This binding appears to be the basis for age-dependent human lens coloration and possibly ARN cataract. These findings suggest that most, if not all, of the features of ARN cataract may be explained on the basis of the onset of the lens bamer in middle age, and the subsequent oxidation and reaction of the nuclear proteins with UV filters. It is the aim of this grant application to investigate this proposal. If confirmed, this would have major implications for future cataract treatment, since it offers hope that drug intervention may be possible to prevent, or delay, ARN cataract.
The specific aims are to: 1. identify the sites of attachment of the UV filters, kynurenine, 3-hydroxykynurenine and 3-hydroxykynurenine glucoside to lens crystallins from older normal, as well as ARN cataract lenses and 2. establish a long-term culture facility for intact human lenses and to employ this to investigate: a) the bather to diffusion in older lenses, b) the binding of UV filters to crystallins in intact lenses as well as c) inhibition of the UV filter biosynthetic pathway as a pharmacological strategy to prevent nuclear cataract.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY013570-02
Application #
6525136
Study Section
Visual Sciences A Study Section (VISA)
Program Officer
Liberman, Ellen S
Project Start
2001-09-30
Project End
2004-09-29
Budget Start
2002-09-30
Budget End
2003-09-29
Support Year
2
Fiscal Year
2002
Total Cost
$75,000
Indirect Cost
Name
University of Wollongong
Department
Type
DUNS #
750735144
City
Wollongong
State
Country
Australia
Zip Code
Hooi, Michelle Yu Sung; Raftery, Mark J; Truscott, Roger John Willis (2012) Racemization of two proteins over our lifespan: deamidation of asparagine 76 in ýýS crystallin is greater in cataract than in normal lenses across the age range. Invest Ophthalmol Vis Sci 53:3554-61
Hooi, Michelle Yu Sung; Raftery, Mark J; Truscott, Roger John Willis (2012) Age-dependent deamidation of glutamine residues in human ýýS crystallin: deamidation and unstructured regions. Protein Sci 21:1074-9
Truscott, Roger J W; Mizdrak, Jasminka; Friedrich, Michael G et al. (2012) Is protein methylation in the human lens a result of non-enzymatic methylation by S-adenosylmethionine? Exp Eye Res 99:48-54
Nealon, Jessica R; Blanksby, Stephen J; Donaldson, Paul J et al. (2011) Fatty Acid uptake and incorporation into phospholipids in the rat lens. Invest Ophthalmol Vis Sci 52:804-9
Hooi, Michelle Yu Sung; Truscott, Roger J W (2011) Racemisation and human cataract. D-Ser, D-Asp/Asn and D-Thr are higher in the lifelong proteins of cataract lenses than in age-matched normal lenses. Age (Dordr) 33:131-41
Truscott, Roger J W; Comte-Walters, Susana; Ablonczy, Zsolt et al. (2011) Tight binding of proteins to membranes from older human cells. Age (Dordr) 33:543-54
Hains, Peter G; Truscott, Roger J W (2010) Age-dependent deamidation of lifelong proteins in the human lens. Invest Ophthalmol Vis Sci 51:3107-14
Beebe, David C; Truscott, Roger J W (2010) Counterpoint: The lens fluid circulation model--a critical appraisal. Invest Ophthalmol Vis Sci 51:2306-10; discussion 2310-2
Zhu, Xiangjia; Gaus, Katharina; Lu, Yi et al. (2010) ?- and ?-crystallins modulate the head group order of human lens membranes during aging. Invest Ophthalmol Vis Sci 51:5162-7
Friedrich, Michael G; Truscott, Roger J W (2010) Large-scale binding of *-crystallin to cell membranes of aged normal human lenses: a phenomenon that can be induced by mild thermal stress. Invest Ophthalmol Vis Sci 51:5145-52

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