Loss of thiol repair systems in human cataractous lenses

The purpose of this study was to investigate the thiol repair systems of thioltransferase (TTase) and thioredoxin (Trx) and oxidation-damaged proteins in human cataractous lenses. Cataractous lenses in humans (57-85 years of age) were classified into cortical, nuclear, mixed, mature, and hypermature...

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Bibliographic Details
Published in:Investigative ophthalmology & visual science 2014-12, Vol.56 (1), p.598-605
Main Authors: Wei, Min, Xing, Kui-Yi, Fan, Yin-Chuan, Libondi, Teodosio, Lou, Marjorie F
Format: Article
Language:English
Subjects:
Aged
Aged, 80 and over
Aging - metabolism
Cataract - metabolism
Cataract - pathology
Female
Glutaredoxins - metabolism
Humans
Immunoblotting
Lens, Crystalline - metabolism
Lens, Crystalline - pathology
Male
Middle Aged
Oxidative Stress
Thioredoxins - metabolism
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Summary:The purpose of this study was to investigate the thiol repair systems of thioltransferase (TTase) and thioredoxin (Trx) and oxidation-damaged proteins in human cataractous lenses. Cataractous lenses in humans (57-85 years of age) were classified into cortical, nuclear, mixed, mature, and hypermature cataract types by using a lens opacity classification system, and were obtained by extracapsular cataract extraction (ECCE) procedure. Cortical and nuclear cataracts were grouped by decreasing order of visual acuity into optical chart reading (R), counting fingers (CF), hand motion (HM), and light perception (LP). ECCE lens homogenate was analyzed for glutathione (GSH) level and enzyme activities of TTase, glutathione reductase (GR), Trx, and thioredoxin reductase (TR). Cortical and nuclear cataractous lenses (8 of each) with visual acuity better than HM were each dissected into cortical and nuclear portions for measurement of glyceraldehyde 3-phosphate dehydrogenase (G3PD) activity. Clear lenses (in humans 49-71 years of age) were used as control. Compared with control, all cataractous lenses lost more than 80% GSH and 70% GR; TR and Trx activity; and 40% to 70% TTase activity, corroborated with the loss in visual acuity. Among cataracts with R and CF visual acuity, cortical cataract lost more cortical G3PD activity (18% of control) than that of nuclear cataract (50% of control), whereas GSH depletion and TTase inactivation were similar in both cataracts. Thiol repair systems were damaged in all types of cataracts. Cortical and nuclear cataracts showed differential G3PD inactivation in the cortex, implying those 2 type of cataracts might be formed through different mechanisms.
ISSN:0146-0404
1552-5783
DOI:10.1167/iovs.14-15452