Increased sensitivity of amino-arm truncated betaA3-crystallin to UV-light-induced photoaggregation.
Invest Ophthalmol Vis Sci
; 46(9): 3263-73, 2005 Sep.
Article
em En
| MEDLINE
| ID: mdl-16123428
ABSTRACT
PURPOSE:
Exposure to UV-B light (wavelength, 290-320 nm) is a well-documented risk factor for age-related cataracts. As the lens ages, beta-crystallins tend to undergo proteolytic cleavage of their terminal extensions. To delineate the effects of loss of terminal arms on beta-crystallin function, the sensitivity of purified recombinant wild-type (rbetaA3) to UV-irradiation induced aggregation was compared with that of betaA3-crystallin missing the N-terminal extension (rbetaA3tr).METHODS:
Proteins were expressed in baculovirus-infected Sf9 cells and purified by chromatography. Purified protein solutions (pH 7.4) were reduced by using Tris (2-carboxyethyl) phosphine HCl and irradiated with a 308-nm excimer laser at physiologically relevant UV doses and wavelengths (308 nm), and light-scattering (633 nm) was measured. Irradiated crystallins were analyzed by matrix-assisted desorption ionization (MALDI) and tandem liquid chromatography/mass spectrometry (LC-MS/MS).RESULTS:
UV-irradiation of both rbetaA3 and rbetaA3tr resulted in major loss of soluble protein, as shown by absorption at 280 nm, size-exclusion chromatography (SEC) and SDS-PAGE, with concomitant formation of insoluble aggregates producing light-scattering. Compared with wild-type rbetaA3, rbetaA3tr showed a significant tendency to begin scattering light at lower UV dose and had a higher aggregation rate with increasing UV exposure. Changes in irradiated crystallins include aggregation and cross-linking, photolysis, and oxidation of methionine and tryptophan residues.CONCLUSIONS:
Loss of beta-crystallin terminal arms appears to increase their tendency to aggregate in response to UV irradiation, suggesting that this loss in the maturing lens may increase susceptibility to age-related cataract.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Raios Ultravioleta
/
Cristalinas
Tipo de estudo:
Diagnostic_studies
/
Risk_factors_studies
Limite:
Animals
Idioma:
En
Revista:
Invest Ophthalmol Vis Sci
Ano de publicação:
2005
Tipo de documento:
Article
País de afiliação:
Estados Unidos