Analysis of Common Deletion (CD) and a novel deletion of mitochondrial DNA induced by ionizing radiation
Analysis of Common Deletion (CD) and a novel deletion of mitochondrial DNA induced by ionizing radiation
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DOI：
10.1080/09553000701370878
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发表时间：
2007-01-01
影响因子：
2.6
通讯作者：
Fukumoto, Manabu
中科院分区：
文献类型：
--
作者：
Wang, Lu;Kuwahara, Yoshikazu;Fukumoto, Manabu
目的：为了确定细胞辐射暴露的支持性证据，我们分析了电离辐射暴露与线粒体DNA（mtDNA）缺失诱导之间的关系。材料和方法：利用经X射线长期照射后建立的人肝母细胞瘤细胞系HepG 2及其衍生物HepG 2-A、-89和-400，用聚合酶链反应（PCR）和实时荧光定量PCR分析细胞经辐射和遗传毒性处理后mtDNA的缺失情况。常见缺失（CD）是研究最广泛的mtDNA缺失，在5 Gray（戈伊）X射线照射后24 h内可诱导CD的发生，并与mtDNA的复制有关。暴露后几天，由于含有诱导CD的线粒体的细胞死亡，CD变得不可检测。此外，我们还发现了一种新的mtDNA缺失，包括核苷酸位置8435和13，368之间的4934个碱基对缺失（4934 del）。诱导4934 del所需的电离辐射剂量低于CD，这与所用辐射的质量无关，并且不受过氧化氢（H2 O2）和其他遗传毒性试剂（包括博来霉素）的诱导。然而，CD是由电离辐射诱导的，在辐射暴露后的某个时间点检测到的CD的量取决于CD诱导的初始频率和具有含CD的mtDNA的细胞的死亡率。因此，本研究中发现的新mtDNA缺失将用于确定细胞是否暴露于电离辐射。
Purpose: In order to identify supportive evidence of radiation exposure to cells, we analyzed the relationship between exposure to ionizing radiation and the induction of deletions in mitochondrial DNA ( mtDNA).Materials and methods: Using human hepatoblastoma cell line, HepG2 and its derivatives, HepG2-A, -89 and -400, established after long term exposure to X-ray, mtDNA deletions were analyzed by polymerase chain reaction (PCR) and real-time PCR after cells were subjected to radiation and genotoxic treatments.Results: Common Deletion (CD), the most extensively studied deletion of mtDNA, was induced within 24 h after exposure to 5 Gray(Gy) of X-rays and was associated with replication of mtDNA. CD became undetectable several days after the exposure due to the death of cells containing mitochondria within which CD had been induced. Furthermore, we found a novel mtDNA deletion that consisted of a 4934 base-pair deletion (4934del) between nucleotide position 8435 and 13,368. A lower dose of ionizing radiation was required to induce the 4934del than for CD and this was independent of the quality of radiation used and was not induced by treatments with hydrogen peroxide ( H2O2) and other genotoxic reagents including bleomycin.Conclusion: CD is induced by ionizing radiation, however, the amount of CD detected at a certain point in time after radiation exposure is dependent on the initial frequency of CD induced and the death rate of cells with mtDNA containing CD. The novel mtDNA deletion found in this study, therefore, will be used to determine whether cells were exposed to ionizing radiation.