title: Expression and proteolytic activity of calpain in lens epithelial cells of oxidative cataract.
abstract: 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.
authors.affiliation: Eye Center, Second Affiliated Hospital, Medical College, Zhejiang University, Hangzhou 310009, China.
authors.forename: Wen
authors.initials: W
authors.lastname: Xu
authors.forename: Ke
authors.initials: K
authors.lastname: Yao
authors.forename: Zhao-hui
authors.initials: ZH
authors.lastname: Sun
authors.forename: Kai-jun
authors.initials: KJ
authors.lastname: Wang
authors.forename: Xing-chao
authors.initials: XC
authors.lastname: Shentu
mesh_terms: 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
chemical_list: D002154:Calpain; C449000:m-calpain; D002118:Calcium