Mitochondria-targeted superoxide dismutase (SOD2) regulates radiation resistance and radiation stress response in HeLa cells.
Reactive oxygen species (ROS) act as a mediator of ionizing radiation-induced cellular damage. Previous studies have indicated that MnSOD (SOD2) plays a critical role in protection against ionizing radiation in mammalian cells. In this study, we constructed two types of stable HeLa cell lines overexpressing SOD2, HeLa S3/SOD2 and T-REx HeLa/SOD2, to elucidate the mechanisms underlying the protection against radiation by SOD2. SOD2 overexpression in mitochondria enhanced the survival of HeLa S3 and T-REx HeLa cells following γ-irradiation. The levels of γH2AX significantly decreased in HeLa S3/SOD2 and T-REx HeLa/SOD2 cells compared with those in the control cells. MitoSox(TM) Red assays showed that both lines of SOD2-expressing cells showed suppression of the superoxide generation in mitochondria. Furthermore, flow cytometry with a fluorescent probe (2',7'-dichlorofluorescein) revealed that the cellular levels of ROS increased in HeLa S3 cells during post-irradiation incubation, but the increase was markedly attenuated in HeLa S3/SOD2 cells. DNA microarray analysis revealed that, of 47,000 probe sets analyzed, 117 and 166 probes showed more than 2-fold changes after 5.5 Gy of γ-irradiation in control and HeLa S3/SOD2 cells, respectively. Pathway analysis revealed different expression profiles in irradiated control cells and irradiated SOD2-overexpressing cells. These results indicate that SOD2 protects HeLa cells against cellular effects of γ-rays through suppressing oxidative stress in irradiated cells caused by ROS generated in the mitochondria and through regulating the expression of genes which play a critical role in protection against ionizing radiation.
Department of Biological Sciences, Graduate School of Science, Kyoto University, Japan.
Ayaka
A
Hosoki
Shin-Ichiro
S
Yonekura
Qing-Li
QL
Zhao
Zheng-Li
ZL
Wei
Ichiro
I
Takasaki
Yoshiaki
Y
Tabuchi
Li-Li
LL
Wang
Shiga
S
Hasuike
Takaharu
T
Nomura
Akira
A
Tachibana
Kazunari
K
Hashiguchi
Shuji
S
Yonei
Takashi
T
Kondo
Qiu-Mei
QM
Zhang-Akiyama
D053903:DNA Breaks, Double-Stranded; D004790:Enzyme Induction; D005720:Gamma Rays / Q000009:adverse effects; D005786:Gene Expression Regulation / Q000528:radiation effects*; D053263:Gene Regulatory Networks / Q000528:radiation effects; D006367:HeLa Cells / Q000378:metabolism / Q000528:radiation effects; D006801:Humans; D008928:Mitochondria / Q000378:metabolism; D009363:Neoplasm Proteins / Q000502:physiology*; D020411:Oligonucleotide Array Sequence Analysis; D018384:Oxidative Stress / Q000502:physiology / Q000528:radiation effects; D011836:Radiation Tolerance / Q000235:genetics / Q000502:physiology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000502:physiology; D013482:Superoxide Dismutase / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D013481:Superoxides / Q000378:metabolism; D000099156:Superoxide Dismutase 2
D009363:Neoplasm Proteins; D017382:Reactive Oxygen Species; D011993:Recombinant Fusion Proteins; D013482:Superoxide Dismutase; D013481:Superoxides; D000099156:Superoxide Dismutase 2