TY - JOUR
T1 - Crystallin degradation and insolubilization in regions of young rat lens with calcium ionophore cataract
AU - Iwasaki, N.
AU - David, L. L.
AU - Shearer, T. R.
N1 - Copyright:
Copyright 2004 Elsevier B.V., All rights reserved.
PY - 1995
Y1 - 1995
N2 - Purpose. To determine if the susceptibility of rat lenses to cataract formation in culture changes with increasing age and to investigate the regional differences in crystallin degradation and insolubilization during the formation of cataracts in cultured lenses. Methods. Lenses from 4-week- old (young group) and 12-week-old (adult group) rats were divided into four subgroups: noncultured control, cultured control, cultured in calcium ionophore A23187, and cultured in ionophore plus calpain inhibitor E64. Lenses were cultured for 7 days, and the cortex and nucleus were homogenized and separated into water-soluble and water-insoluble fractions. Two- dimensional electrophoresis and N-terminal sequencing were then performed. Results. Young lenses treated with ionophore produced thin cortical and dense nuclear opacities. Adult lenses treated with ionophore also developed thin cortical opacity, but no nuclear opacity was observed, even though a large increase in the concentration of insoluble protein occurred. Two-dimensional electrophoresis and sequencing suggested that calpain caused protein degradation in the cortex region. However, unlike nuclear opacity, the formation of opacity in the cortex was not inhibited by E64 in young or adult lenses. Conclusions. Calpain was activated, and crystallins were proteolyzed in the cortex of ionophore-treated lenses. However, cortical opacity was not the result of proteolysis by calpain. Maturation also decreased the susceptibility of rat lens nucleus to calcium ionophore cataract.
AB - Purpose. To determine if the susceptibility of rat lenses to cataract formation in culture changes with increasing age and to investigate the regional differences in crystallin degradation and insolubilization during the formation of cataracts in cultured lenses. Methods. Lenses from 4-week- old (young group) and 12-week-old (adult group) rats were divided into four subgroups: noncultured control, cultured control, cultured in calcium ionophore A23187, and cultured in ionophore plus calpain inhibitor E64. Lenses were cultured for 7 days, and the cortex and nucleus were homogenized and separated into water-soluble and water-insoluble fractions. Two- dimensional electrophoresis and N-terminal sequencing were then performed. Results. Young lenses treated with ionophore produced thin cortical and dense nuclear opacities. Adult lenses treated with ionophore also developed thin cortical opacity, but no nuclear opacity was observed, even though a large increase in the concentration of insoluble protein occurred. Two-dimensional electrophoresis and sequencing suggested that calpain caused protein degradation in the cortex region. However, unlike nuclear opacity, the formation of opacity in the cortex was not inhibited by E64 in young or adult lenses. Conclusions. Calpain was activated, and crystallins were proteolyzed in the cortex of ionophore-treated lenses. However, cortical opacity was not the result of proteolysis by calpain. Maturation also decreased the susceptibility of rat lens nucleus to calcium ionophore cataract.
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M3 - Article
C2 - 7843919
AN - SCOPUS:0028888585
SN - 0146-0404
VL - 36
SP - 502
EP - 509
JO - Investigative Ophthalmology and Visual Science
JF - Investigative Ophthalmology and Visual Science
IS - 2
ER -