An Oxidized Purine Nucleoside Triphosphatase, MTH1, Suppresses Cell Death Caused by Oxidative Stress*
An Oxidized Purine Nucleoside Triphosphatase, MTH1, Suppresses Cell Death Caused by Oxidative Stress*
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DOI：
10.1074/jbc.m306201200
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发表时间：
2003-09
影响因子：
4.8
通讯作者：
Daisuke Yoshimura;K. Sakumi;M. Ohno;Y. Sakai;M. Furuichi;S. Iwai;Y. Nakabeppu
中科院分区：
文献类型：
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作者：
Daisuke Yoshimura;K. Sakumi;M. Ohno;Y. Sakai;M. Furuichi;S. Iwai;Y. Nakabeppu
MTH 1水解氧化嘌呤核苷三磷酸，如8-氧代-2 ′-脱氧鸟苷5′-三磷酸（8-oxo-dGTP）和2-羟基-2 ′-脱氧腺苷5′-三磷酸（2-OH-dATP），从而保护细胞免受其错误掺入DNA引起的损伤。在本研究中，我们建立了MTH 1基因缺失的小鼠胚胎成纤维细胞，这些细胞对暴露于H2 O2引起的细胞功能障碍和死亡高度敏感，具有线粒体中积累的固缩和电子致密沉积物的形态学特征。观察到的细胞死亡是独立的聚（ADP-核糖）聚合酶和半胱天冬酶。一个高效液相色谱串联质谱分析和免疫荧光显微镜显示连续积累的8-氧代鸟嘌呤在核和线粒体DNA暴露后，过氧化氢。在MTH 1基因缺失小鼠胚胎成纤维细胞中观察到的所有H2 O2诱导的改变均被野生型人MTH 1（hMTH 1）的表达有效抑制，而它们仅被8-oxo-dGT酶或2-OH-dATP酶活性缺陷的突变型hMTH 1的表达部分抑制。因此，人类MTH 1通过水解包括8-oxo-dGTP和2-OH-dATP在内的氧化嘌呤核苷酸来保护细胞免受H2 O2诱导的细胞功能障碍和死亡，这些改变可能部分归因于线粒体功能障碍。
MTH1 hydrolyzes oxidized purine nucleoside triphosphates such as 8-oxo-2′-deoxyguanosine 5′-triphosphate (8-oxo-dGTP) and 2-hydroxy-2′-deoxyadenosine 5′-triphosphate (2-OH-dATP) and thus protects cells from damage caused by their misincorporation into DNA. In the present study, we established MTH1-null mouse embryo fibroblasts that were highly susceptible to cell dysfunction and death caused by exposure to H2O2, with morphological features of pyknosis and electron-dense deposits accumulated in mitochondria. The cell death observed was independent of both poly(ADP-ribose) polymerase and caspases. A high performance liquid chromatography tandem mass spectrometry analysis and immunofluorescence microscopy revealed a continuous accumulation of 8-oxo-guanine both in nuclear and mitochondrial DNA after exposure to H2O2. All of the H2O2-induced alterations observed in MTH1-null mouse embryo fibroblasts were effectively suppressed by the expression of wild type human MTH1 (hMTH1), whereas they were only partially suppressed by the expression of mutant hMTH1 defective in either 8-oxo-dGTPase or 2-OH-dATPase activity. Human MTH1 thus protects cells from H2O2-induced cell dysfunction and death by hydrolyzing oxidized purine nucleotides including 8-oxo-dGTP and 2-OH-dATP, and these alterations may be partly attributed to a mitochondrial dysfunction.