Hepatitis B virus X stimulates redox signaling through activation of ataxia telangiectasia mutated kinase.
Hepatitis B virus X stimulates redox signaling through activation of ataxia telangiectasia mutated kinase.
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发表时间：
2014-04
影响因子：
1.4
通讯作者：
Y. Matsuda;Ayumi Sanpei;T. Wakai;Masayuki Kubota;Mami Osawa;Y. Hirose;J. Sakata;Takashi Kobayashi;Shun Fujimaki;M. Takamura;S. Yamagiwa;M. Yano;S. Ohkoshi;Y. Aoyagi
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文献类型：
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作者：
Y. Matsuda;Ayumi Sanpei;T. Wakai;Masayuki Kubota;Mami Osawa;Y. Hirose;J. Sakata;Takashi Kobayashi;Shun Fujimaki;M. Takamura;S. Yamagiwa;M. Yano;S. Ohkoshi;Y. Aoyagi
B型肝炎病毒X（HBX）蛋白在肿瘤发生中起重要作用，但其作用机制尚不清楚。通过检测HBX基因转染细胞和转基因小鼠中ATM的磷酸化水平，研究了共济失调毛细血管扩张突变（ATM）激酶在增强的氧化还原系统中的参与，这些小鼠在用过氧化氢（H2 O2）或抗氧化剂处理氧化还原系统后进行了操作。Western印迹和免疫染色显示HBX在体外（3.2倍; p<0.05）和体内（4倍; p<0.05）均显著增加磷酸-ATM，并且这种作用被抗氧化剂处理消除。与对照组相比，HBX表达细胞中PKC-δ的水平增加了3.5倍。核定位NF-E2相关因子2（Nrf 2）在暴露于H2 O2的HBX表达细胞中增加，但在用rottlerin，KU 55933或咖啡因处理后保持在较低水平。在HBX表达细胞和转基因小鼠中抗氧化分子的水平增加，表明HBX刺激Nrf 2介导的氧化还原系统。在ATM抑制剂KU 55933或咖啡因存在下，用过氧化氢处理的HBX表达细胞中细胞内活性氧（ROS）的水平显著增加。在暴露于H2 O2之前用KU 55933或咖啡因处理表达HBX的细胞，细胞凋亡率分别增加至33±4%（p<0.05）和22±4%（p<0.05）。总的来说，HBX刺激ATM介导的PKC-δ/Nrf 2途径，并维持氧化还原系统的增强活性。因此，操纵ATM激酶活性可能是治疗HBX诱导的致癌作用的有用策略。
Hepatitis B virus X (HBX) protein plays a crucial role in carcinogenesis, but its mechanism is unclear. The involvement of ataxia telangiectasia mutated (ATM) kinase in the enhanced redox system was investigated by examining the phosphorylation level of ATM in HBX gene-transfected cells and in transgenic mice following redox system manipulation by treatment with hydrogen peroxide (H2O2) or antioxidant. Western blotting and immunostaining showed that phospho-ATM was significantly increased by HBX both in vitro (3.2-fold; p<0.05) and in vivo (4-fold; p<0.05), and this effect was abrogated by antioxidant treatment. The level of PKC-δ in HBX-expressing cells was increased 3.5-fold compared to controls. Nuclear localized NF-E2-related factor 2 (Nrf2) was increased in HBX-expressing cells exposed to H2O2, but remained at lower levels after the treatment with rottlerin, KU55933, or caffeine. The levels of anti-oxidant molecules were increased in HBX expressing cells and in transgenic mice, indicating that HBX stimulates the Nrf2-mediated redox system. The levels of intracellular reactive oxygen species (ROS) were significantly increased in HBX-expressing cells treated with hydrogen peroxide in the presence of ATM inhibitor KU55933 or caffeine. Treatment of HBX-expressing cells with KU55933 or caffeine before the exposure to H2O2 increased the ratio of cell apoptosis to 33±4% (p<0.05) and 22±4% (p<0.05), respectively. Collectively, HBX stimulates the ATM-mediated PKC-δ/Nrf2 pathway, and maintains the enhanced activity of the redox system. Therefore, manipulating ATM kinase activity might be a useful strategy for treating HBX-induced carcinogenesis.