JZUS - Journal of Zhejiang University SCIENCE

Journal of Zhejiang University SCIENCE A 2004 Vol.5 No.6 P.743-748

http://doi.org/10.1631/jzus.2004.0743

Expression and proteolytic activity of calpain in lens epithelial cells of oxidative cataract

Author(s): XU Wen, YAO Ke, SUN Zhao-hui, WANG Kai-jun, SHENTU Xing-chao
Affiliation(s): Eye Center, Second Affiliated Hospital, Medical College, Zhejiang University, Hangzhou 310009, China
Corresponding email(s): xlren@zju.edu.cn
Key Words: Cataract, Lens epithelial cell, Hydrogen peroxide, Calpain, Calcium

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Abstract: Objective: To study the role of calpain in the mechanism of oxidative cataract through detecting the level of intracellular free Ca2+, the expression and proteolytic activity of calpain in the lens epithelial cells (LECs) of H2O2-induced cataract. Methods: Rat lenses were cultured in vitro and cataract was induced by H2O2. The level of intracellular free Ca2+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 Ca²⁺ (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 H₂O₂-induced and control group at 6, 12 and 24 h, respectively. Conclusions: H₂O₂ can increase intracellular free Ca²⁺, then enhance the expression and proteolytic activity of calpain which may play a role in the mechanism of oxidative cataract of rat.

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