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J. H. Ho, K.-C. Tseng, W.-H. Ma, K.-H. Chen, O. K. Lee, Y. Su; Anti-Oxidative Capacity of Thymosin Beta-4 in Human Cornea Epithelial Cells. Invest. Ophthalmol. Vis. Sci. 2008;49(13):2958.
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We previously demonstrated that internalization was essential for exogenous thymosin beta-4 (Tβ4) to protect human cornea epithelial (HCE-T) cells against ROS-induced apoptosis, and the purpose of this study is to further elucidate its protective mechanism.
HCE-T cells were incubated with histidine-tagged Tβ4 (1 µg/ml) for two hours before being treated with H2O2 (200 µM). Activation of caspases-8 and -9 was examined by flow cytometry and the latter was further analyzed by colorimetric assay. Intracellular reactive oxygen species (ROS) level was measured by flowcytometry using 2’,7’-dichlorodihydrofluorescein diacetate (H2DCFH-DA) as probes. Protein levels and gene expression of manganese-superoxide dismutase (Mn-SOD), copper/zinc-superoxide dismutase (Cu/Zn-SOD) and catalase were analyzed by Western blotting and real-time RT-PCR, respectively.
It was found that Tβ4 protected HCE-T cells from H2O2-induced apoptosis by reducing both caspase-9 activation and intracellular ROS levels. It was further discovered that Tβ4 increased the expression of Mn-SOD and Cu/Zn-SOD. Moreover, after the addition of H2O2, catalase was also up-regulated by Tβ4 at both transcription and translation levels.
Tβ4 was found capable of up-regulating anti-oxidative enzymes in human corneal epithelial cells and increasing the resistance of the human corneal epithelial cells to ROS-induced apoptosis.
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