Department of Biology, School of Medicine, Nara Medical University, Kashihara, Nara, Japan.
Int J Radiat Oncol Biol Phys. 2010 Nov 15;78(4):1171-6. doi: 10.1016/j.ijrobp.2010.04.062. Epub 2010 Aug 21.
It has been reported that priming irradiation or conditioning irradiation with a low dose of X-rays in the range of 0.02-0.1 Gy induces a p53-dependent adaptive response in mammalian cells. The aim of the present study was to clarify the effect of space radiations on the adaptive response.
Two human lymphoblastoid cell lines were used; one cell line bears a wild-type p53 (wtp53) gene, and another cell line bears a mutated p53 (mp53) gene. The cells were frozen during transportation on the space shuttle and while in orbit in the International Space Station freezer for 133 days between November 15, 2008 and March 29, 2009. After the frozen samples were returned to Earth, the cells were cultured for 6 h and then exposed to a challenging X-ray-irradiation (2 Gy). Cellular sensitivity, apoptosis, and chromosome aberrations were scored using dye-exclusion assays, Hoechst33342 staining assays, and chromosomal banding techniques, respectively.
In cells exposed to space radiations, adaptive responses such as the induction of radioresistance and the depression of radiation-induced apoptosis and chromosome aberrations were observed in wtp53 cells but not in mp53 cells.
These results have confirmed the hypothesis that p53-dependent adaptive responses are apparently induced by space radiations within a specific range of low doses. The cells exhibited this effect owing to space radiations exposure, even though the doses in space were very low.
据报道，在 0.02-0.1Gy 范围内用低剂量 X 射线进行预照射或调理照射会诱导哺乳动物细胞中 p53 依赖性的适应反应。本研究的目的是阐明空间辐射对适应反应的影响。
使用了两种人类淋巴母细胞系；一种细胞系携带野生型 p53（wtp53）基因，另一种细胞系携带突变型 p53（mp53）基因。这些细胞在航天飞机上运输期间和在国际空间站的冷冻器中于 2008 年 11 月 15 日至 2009 年 3 月 29 日期间进行轨道飞行时被冷冻。冷冻样本返回地球后，将细胞培养 6 小时，然后用挑战性 X 射线照射（2Gy）。使用染料排除试验、Hoechst33342 染色试验和染色体带型技术分别评分细胞敏感性、细胞凋亡和染色体畸变。
在暴露于空间辐射的细胞中，wtp53 细胞中观察到适应反应，如放射抗性的诱导以及辐射诱导的细胞凋亡和染色体畸变的抑制，但在 mp53 细胞中未观察到。
这些结果证实了这样的假设，即在特定的低剂量范围内，p53 依赖性的适应反应显然是由空间辐射引起的。即使在空间中的剂量非常低，细胞也会因暴露于空间辐射而表现出这种效应。
