Leatherbarrow Emma L, Harper Jane V, Cucinotta Francis A, O'Neill Peter
DNA Damage Group, Radiation and Genome Stability Unit, Medical Research Council, Harwell, Oxfordshire, UK.
Int J Radiat Biol. 2006 Feb;82(2):111-8. doi: 10.1080/09553000600599783.
To investigate quantitatively the induction and rejoining of DNA double strand breaks (DSB) in V79-4 and xrs-5 Chinese hamster cells and HF19 human fibroblast cells, using the phosphorylation of the histone protein H2AX (gamma-H2AX) as an indicator of DSB, exposed to low doses of either low linear energy transfer (LET) (60)Co gamma-rays or high LET a-particles.
Cells were irradiated with low or high LET (20 - 2000 mGy). The gamma-H2AX foci were detected using immunohistochemistry and quantified by image analysis.
The number of DSB determined 30 min post gamma-irradiation at 37 degrees C is 12.2 (+/-1.5), 13.5 (+/-1.6) and 19.1 (+/-1.7) foci/cell/Gy for V79-4, xrs-5 and HF19 cells respectively, comparable with levels detected in V79-4 cells using pulse field gel electrophoresis. 6 h post gamma-irradiation, gamma-H2AX foci levels in V79-4 and HF19 cells approach control levels but remain higher in DSB repair deficient xrs-5 cells. Gamma-H2AX foci levels remain significantly higher than controls at 6 h in a-irradiated cells.
Gamma-radiation and alpha-radiation induced the phosphorylation of H2AX in response to DSB at low doses; the variation in the rate of dephosphorylation of induced foci are dependent both on radiation quality and cell characteristics.
以组蛋白H2AX（γ-H2AX）的磷酸化作为DNA双链断裂（DSB）的指标，定量研究V79-4和xrs-5中国仓鼠细胞以及HF19人成纤维细胞在受到低剂量低线性能量传递（LET）（60）Coγ射线或高LETα粒子照射后DSB的诱导和重新连接情况。
细胞接受低或高LET（20 - 2000 mGy）照射。使用免疫组织化学检测γ-H2AX焦点，并通过图像分析进行定量。
在37℃γ射线照射后30分钟测定的DSB数量，V79-4、xrs-5和HF19细胞分别为12.2（±1.5）、13.5（±1.6）和19.1（±1.7）个焦点/细胞/戈瑞，与使用脉冲场凝胶电泳在V79-4细胞中检测到的水平相当。γ射线照射后6小时，V79-4和HF19细胞中的γ-H2AX焦点水平接近对照水平，但在DSB修复缺陷的xrs-5细胞中仍较高。在α射线照射的细胞中，6小时时γ-H2AX焦点水平仍显著高于对照。
γ辐射和α辐射在低剂量时会因DSB诱导H2AX磷酸化；诱导焦点去磷酸化速率的变化既取决于辐射质量，也取决于细胞特性。
