HIV-TAT mediated protein transduction of Cu/Zn-superoxide dismutase-1 (SOD(1)) protects skin cells from ionizing radiation

BACKGROUND: Radiation-induced skin injury remains a serious concern during radiotherapy. Cu/Zn-superoxide dismutase (Cu/Zn-SOD, SOD(1)) is a conserved enzyme for scavenging superoxide radical in cells. Because of the integrity of cell membranes, exogenous molecule is not able to be incorporated into cells, which limited the application of natural SOD(1). The aim of this study was to evaluate the protective role of HIV-TAT protein transduction domain mediated protein transduction of SOD(1) (TAT-SOD(1)) against ionizing radiation. METHODS: The recombinant TAT-SOD(1) and SOD(1) were obtained by prokaryotic–based protein expression system. The transduction effect and biological activity of TAT-SOD(1) was measured by immunofluorescence and antioxidant capability assays in human keratinocyte HaCaT cells. Mito-Tracker staining, reactive oxygen species (ROS) generation assay, cell apoptosis analysis and malondialdehyde (MDA) assay were used to access the protective effect of TAT- SOD(1). RESULTS: Uptake of TAT-SOD(1) by HaCaT cells retained its biological activity. Compared with natural SOD(1), the application of TAT-SOD(1) significantly enhanced the viability and decreased the apoptosis induced by X-ray irradiation. Moreover, TAT-SOD(1) reduced ROS and preserved mitochondrial integrity after radiation exposure in HaCaT cells. Radiation-induced γH2AX foci, which are representative of DNA double strand breaks, were decreased by pretreatment with TAT-SOD(1). Furthermore, subcutaneous application of TAT-SOD(1) resulted in a significant decrease in 45 Gy electron beam-induced ROS and MDA concentration in the skins of rats. CONCLUSIONS: This study provides evidences for the protective role of TAT-SOD(1) in alleviating radiation-induced damage in HaCaT cells and rat skins, which suggests a new therapeutic strategy for radiation-induced skin injury.