Levels of γ-H2AX foci after low-dose-rate irradiation reveal a DNA DSB rejoining defect in cells from human ATM heterozygotes in two AT families and in another apparently normal individual
Levels of γ-H2AX foci after low-dose-rate irradiation reveal a DNA DSB rejoining defect in cells from human ATM heterozygotes in two AT families and in another apparently normal individual
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DOI：
10.1667/rr3604.1
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发表时间：
2006-09-01
影响因子：
3.4
通讯作者：
Bedford, J. S.
中科院分区：
文献类型：
--
作者：
Kato, Takamitsu A.;Nagasawa, Hatsumi;Bedford, J. S.
我们研究了使用γ - h2ax测定，反映DNA双链断裂的存在，作为识别对电离辐射轻度过敏的个体的可能手段，例如一些ATM杂合子。我们比较了6个明显正常个体以及两个独立AT家庭（包括先证、母亲、父亲和每个家庭中三个未受影响的兄弟姐妹）的细胞辐照后γ - h2ax病灶的水平。在将1 gy的急性（高剂量率）γ射线剂量递送到非循环接触抑制的单层细胞后，在照射后几乎所有采样时间内，在正常个体（ATM(+/+)）和先验体（ATM(-/-)）的样本之间可以看到明显的差异，但与特异性杂合子（ATM(+/-)）相比，正常细胞没有明显的区别。相比之下，在以10 cGy/h的剂量率连续照射24小时后，与对照组相比，所有已知ATM基因型个体的细胞在每个细胞中观察到明显的病灶数量差异。四个未受影响的兄弟姐妹每个细胞的平均病灶数与专性杂合子相似，而另外两个的平均值与正常对照相似。我们独立确定，在ATM杂合子范围内平均每个细胞有病灶数的兄弟姐妹携带突变等位基因，而辐照后每个细胞有正常病灶数的兄弟姐妹携带正常等位基因。在低剂量率试验中使用淋巴母细胞样细胞株的一组更有限的实验也揭示了与来自同一家族的ATM杂合子相比，正常细胞的明显差异，并开启了将外周血淋巴细胞作为更合适的材料用于检测个体对辐射轻度超敏反应的可能性。(c) 2006年辐射研究学会。
We have investigated the use of the gamma-H2AX assay, reflecting the presence of DNA double-strand breaks, as a possible means for identifying individuals who are mildly hypersensitive to ionizing radiation, such as some ATM heterozygotes. We compared levels of gamma-H2AX foci after irradiation in cells from six apparently normal individuals as well as from individuals from two separate AT families including the proband, mother, father and three unaffected siblings in each family. After a 1-Gy single acute (high-dose-rate) gamma-ray dose delivered to noncycling contact-inhibited monolayers of cells, clear differences were seen between samples from normal individuals (ATM(+/+)) and probands (ATM(-/-)) at nearly all sampling times after irradiation, but no clear distinctions were seen for cells from normal compared to obligate heterozygotes (ATM(+/-)). In contrast, after 24 h of continuous irradiation at a dose rate of 10 cGy/h, appreciable differences in numbers of foci per cell were observed for cells from individuals for all the known ATM genotypes compared with controls. Four unaffected siblings had mean numbers of foci per cell similar to that for the obligate heterozygotes, whereas the other two had mean values similar to that for normal controls. We determined independently that those siblings with mean numbers of foci per cell in the range of ATM heterozygotes carried the mutant allele, while both siblings with a normal number of foci per cell after irradiation had normal alleles. A more limited set of experiments using lymphoblastoid cell strains in the low-dose-rate assay also revealed distinct differences for normal compared to ATM heterozygotes from the same families and opens the possibility of using peripheral blood lymphocytes as a more suitable material for an assay to detect mild hypersensitivities to radiation among individuals. (c) 2006 by Radiation Research Society.