Expression and proteolytic activity of calpain in lens epithelial cells of oxidative cataract.
OBJECTIVE
To study the role of calpain in the mechanism of oxidative cataract through detecting the level of intracellular free Ca(2+), the expression and proteolytic activity of calpain in the lens epithelial cells (LECs) of H(2)O(2)-induced cataract.


METHODS
Rat lenses were cultured in vitro and cataract was induced by H(2)O(2). The level of intracellular free Ca(2+) was measured by fluorescence determination with fura-2/AM. The expression of m-calpain protein in LECs was detected with immunohistochemical method. The proteolytic activity in LECs was measured using a fluorogenic synthetic substrate.


RESULTS
There were significant differences of the level of intracellular free Ca(2+) (P=0.001, 0.000, 0.000), the expression of m-calpain (P=0.001, 0.000, 0.000) and the proteolytic activity of calpain (P=0.001, 0.000, 0.000) between H(2)O(2)-induced and control group at 6, 12 and 24 h, respectively.


CONCLUSIONS
H(2)O(2) can increase intracellular free Ca(2+), then enhance the expression and proteolytic activity of calpain which may play a role in the mechanism of oxidative cataract of rat.
Xu
Wen
W
Eye Center, Second Affiliated Hospital, Medical College, Zhejiang University, Hangzhou 310009, China.
Yao
Ke
K
Sun
Zhao-hui
ZH
Wang
Kai-jun
KJ
Shentu
Xing-chao
XC
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002154:Calpain / Q000378:metabolism*; D002386:Cataract / Q000201:enzymology* / Q000378:metabolism / Q000473:pathology; D004847:Epithelial Cells / Q000201:enzymology* / Q000473:pathology; D015870:Gene Expression; D007908:Lens, Crystalline / Q000201:enzymology* / Q000473:pathology; D010084:Oxidation-Reduction; D051381:Rats; D017207:Rats, Sprague-Dawley
D002154:Calpain; C449000:m-calpain; D002118:Calcium