Abstract
Abstract: :
Purpose: The mechanism of cataract in selenite injected young rats is well documented, and involves calcium accumulation in the nucleus, calpain-induced proteolysis of crystallins and cytoskeletal proteins, phase transition, and crystallin precipitation. However, the mechanism causing loss of integrity of lens epithelial cells induced by an overdose of sodium selenite is unknown. Thus, the purpose of the present experiment was to elucidate the mechanism of selenite cataract by searching for differential gene expression in epithelial cells of lenses from rats developing selenite cataract. Methods: A single subcutaneous injection of sodium selenite (30 µmol/kg body weight) was administered to Sprague-Dawley rats of 12 days of age. One day after injection of selenite, gene expression in lens epithelial cells was analyzed using a commercial DNA array (Atlas Rat 1.2 Array, Clontech Laboratories). Changes in the expression patterns of mRNAs were also confirmed by RT-PCR. Results: Of 1176 genes assayed by hybridization, 91 genes showed differences in expression between normal and selenite lenses on 1 day after injection. The three genes showing the greatest changes were: cytochrome c oxidase subunit I (COX-I) and gastric inhibitory polypeptide (GIP) were decreased, and early growth response protein-1 (EGR-1) was increased. Similar results were also observed 3 days after injection of selenite. Conclusion: Both COX-I and EGR-1 have been reported to be involved in apoptosis. Thus, these results suggest that changes in COX-I and EGR-1 expression in lens epithelial cells might play important roles in apoptosis and altered metabolism leading to selenite cataract.
Keywords: 341 cell death/apoptosis • 338 cataract • 417 gene/expression