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M. R. Fernando, Y. Wang, M. F. Lou; Thioredoxin Has a Growth Factor/Cytokine-Like Property that Generates Reactive Oxygen Species (ROS) and Stimulates Cell Growth in Human Lens Epithelial Cells (HLE B3). Invest. Ophthalmol. Vis. Sci. 2007;48(13):2437.
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© ARVO (1962-2015); The Authors (2016-present)
We have undertaken this study to investigate the mechanism/s by which extra cellular thioredoxin (Trx) stimulated the expression of several antioxidant enzymes in human lens epithelial cells observed previously (Yogorova et al., Exp Eye Res., 2006).
Purified recombinant human Trx was used throughout the studies. Trx-stimulated cell proliferation was determined by manual cell counting. Trx-induced ROS generation was examined using dichlorofluorescein (DCFH) fluorescence by FACS analysis. NADPH oxidase activity was measured by superoxide anion production using lucigenin-amplified chemiluminescence in Trx treated and untreated HLE B3 cells. H2O2 was quantified using the method of Hildebrant et al.
Recombinant human Trx (5 µM) added to culture medium in the absence of fetal bovine serum stimulated the proliferation of HLE B3 cells over a 3 day period. Treating HLE B3 cells with 20 µM Trx resulted in increased DCF fluorescence over the untreated control cells, indicating Trx could stimulate intracellular ROS generation. Co-treatment of the cells with catalase (1 mg/ml) and Trx resulted in a significant decrease in ROS generation. Treatment of HLE B3 cells for 30 min with a NADPH oxidase inhibitor, diphenyleneiodonium chloride (10 µM), prior to Trx treatment resulted in ~ 50% decrease in DCF fluorescence. Cells treated with Trx (20 µM) showed two-fold increase in NADPH oxidase activity as compared to the untreated control.
Based on above observations we propose that Trx possesses a novel growth factor/cytokine-like function in stimulating cell proliferation and specific antioxidant enzyme expressions via ROS-mediated redox signaling by activating membrane-bound NADPH oxidase enzyme.
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