State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou 215123, China.
Department of Nutrition and Food Hygiene, Soochow University of Public Health, Suzhou 215123, China.
Int J Mol Sci. 2020 Dec 6;21(23):9304. doi: 10.3390/ijms21239304.
With the advent of long-duration space explorations, ionizing radiation (IR) may pose a constant threat to astronauts without the protection of Earth's magnetic field, or hypomagnetic field (HMF). However, the potential biological effects of a HMF on the cellular response to IR have not been well characterized so far. In this study, immortalized human bronchial epithelial cells were exposed to X-rays under either a geomagnetic field (GMF, ~50 uT) or HMF (<50 nT) culture condition. A significant increase of the cell survival rate in HMF after radiation was observed by colony formation analysis. The kinetics of DNA double-strand breaks (DSBs), determined by γH2AX foci formation and disappearance, presented a faster decrease of foci-positive cells and a significantly lower mean number of γH2AX foci per nucleus in HMF-cultured cells than in GMF-cultured cells after radiation. In addition, a γH2AX/53BP1 colocalization assay showed an upregulated DSB recovery rate in HMF cultured cells. These findings provided the first evidence that HMF exposure may enhance the cellular DSB repair efficiency upon radiation, and consequently modulate the genotoxic effects of IR.
随着长时间的太空探索的出现，离子辐射（IR）可能会对没有地球磁场或低磁（HMF）保护的宇航员构成持续威胁。然而，到目前为止，HMF 对细胞对 IR 的细胞反应的潜在生物学影响还没有很好地表征。在这项研究中，将永生的人支气管上皮细胞暴露于 X 射线下，分别在存在地磁场（GMF，~50uT）或 HMF（<50nT）的培养条件下进行。通过集落形成分析观察到，辐射后 HMF 中的细胞存活率显着增加。通过 γH2AX 焦点形成和消失来确定 DNA 双链断裂（DSB）的动力学，结果表明，在 HMF 培养的细胞中，焦点阳性细胞的减少速度更快，并且在辐射后每个细胞核中的 γH2AX 焦点的平均数量显着降低。此外，γH2AX/53BP1 共定位测定表明，HMF 培养的细胞中 DSB 修复率提高。这些发现提供了第一个证据，表明 HMF 暴露可能会增强细胞在辐射后的 DSB 修复效率，并因此调节 IR 的遗传毒性作用。
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