Cataract is the leading cause of blindness worldwide and its only cure, surgical removal, can result in complications and places an enormous financial burden on our economy. The prevalence of cataract in the U.S. is expected to more than double by the year 2050. Despite decades of research, the causes of age-related protein aggregation and lens opacity remain ill- defined and no therapies exist to prevent or delay cataract. The long-term goals of our research are to identify modifications to lens proteins during aging and cataractogenesis in order to understand protein aging mechanisms and to develop ways to prevent or delay deleterious events. Recently, we have discovered an age-dependent, non-enzymatic biochemical mechanism that results in significant amounts of both age-related lens protein modification and cataract-related lens protein crosslinking. This chemistry occurs at phosphoserine and cysteine residues and involves modification by glutathione (GSH) and other nucleophiles in the lens including protein thiols resulting in irreversible protein crosslinking. Or hypothesis is that lens protein non-disulfide thiolation by GSH prevents protein-protein crosslinking, but with age this protective mechanism is overwhelmed resulting in irreversible crosslinking, protein aggregation, and lens opacification. To test this hypothesis we will employ state-of-the-art proteomics methodology to further define age-related and cataract-specific modifications, evaluate conditions upon which the chemistry occurs, and validate an animal model for detected modifications and future therapeutic use. Specifically we propose to: 1) characterize and quantify protein non-disulfide thiol modifications and protein crosslinks in normal and cataractous human lenses, 2) determine conditions controlling non-disulfide thiol modification and protein crosslinking, and 3) characterize lens protein non-disulfide modifications and protein crosslinks in an animal model of human nuclear cataract. The proposed experiments are expected to provide new mechanistic details on protein aging that will not only inform the development of new cataract treatments, but also guide therapeutic development for other aging and protein aggregation diseases.

Public Health Relevance

of the proposed studies is that with an improved understanding of lens protein aging and cataract formation, therapies can be developed to prevent or delay the onset of cataract in our increasingly aging population. In addition, the long-term outcomes are expected to reduce the enormous financial costs of cataract treatment and also impact treatment of other aging diseases.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY024258-04
Application #
9313263
Study Section
Biology of the Visual System Study Section (BVS)
Program Officer
Araj, Houmam H
Project Start
2014-07-01
Project End
2019-06-30
Budget Start
2017-07-01
Budget End
2019-06-30
Support Year
4
Fiscal Year
2017
Total Cost
Indirect Cost
Name
Vanderbilt University Medical Center
Department
Biochemistry
Type
Schools of Medicine
DUNS #
965717143
City
Nashville
State
TN
Country
United States
Zip Code
37240
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Wang, Zhen; Schey, Kevin L (2018) Quantification of thioether-linked glutathione modifications in human lens proteins. Exp Eye Res 175:83-89
Friedrich, Michael G; Wang, Zhen; Oakley, Aaron J et al. (2017) Hotspots of age-related protein degradation: the importance of neighboring residues for the formation of non-disulfide crosslinks derived from cysteine. Biochem J 474:2475-2487
Slavi, Nefeli; Wang, Zhen; Harvey, Lucas et al. (2016) Identification and Functional Assessment of Age-Dependent Truncations to Cx46 and Cx50 in the Human Lens. Invest Ophthalmol Vis Sci 57:5714-5722
Truscott, Roger J W; Schey, Kevin L; Friedrich, Michael G (2016) Old Proteins in Man: A Field in its Infancy. Trends Biochem Sci 41:654-664
Truscott, Roger J W; Friedrich, Michael G (2016) The etiology of human age-related cataract. Proteins don't last forever. Biochim Biophys Acta 1860:192-8