Research Centre for Medical Genetics, Russian Academy of Medical Sciences, Moscow, Russia.
Mutat Res. 2011 Jul 1;712(1-2):1-10. doi: 10.1016/j.mrfmmm.2011.03.002. Epub 2011 Mar 12.
The human umbilical vein endothelial cells culture was exposed to X-ray radiation in a low dose of 10cGy. The fragments of extracellular genomic DNA (ecDNA(R)) were isolated from the culture medium after the short-term incubation. A culture medium of unirradiated endothelial cells was then supplemented with ecDNA(R), followed by analysing the cells along the series of parameters (bystander effect). The exposed cells and bystander endotheliocytes showed similar response to low doses: approximation of the 1q12 loci of chromosome 1 and their transposition into the cellular nucleus, change in shape of the endotheliocytic nucleus, activation of the nucleolus organizing regions (NORs), actin polymerization, and an elevated level of DNA double-stranded breaks. Following blockade of TLR9 receptors with oligonucleotide-inhibitor or chloroquine in the bystander cells these effects - except of activation of NORs - on exposure to ecDNA(R) disappeared, with no bystander response thus observed. The presence of the radiation-induced apoptosis in the bystander effect being studied suggests a possibility for radiation-modified ecDNA fragments (i.e., stress signaling factors) to be released into the culture medium, whereas inhibition of TLR9 suggests the binding these ligands to the recipient cells. A similar DNA-signaling pathway in the bystander effect we previously described for human lymphocytes. Integrity of data makes it possible to suppose that a similar signaling mechanism which we demonstrated for lymphocytes (humoral system) might also be mediated in a monolayer culture of cells (cellular tissue) after the development of the bystander effect in them and transfer of stress signaling factors (ecDNA(R)) through the culture medium.
将人脐静脉内皮细胞培养物暴露于低剂量的 10cGy X 射线辐射下。在短期孵育后，从培养基中分离出细胞外基因组 DNA 片段（ecDNA(R)）。然后，将未辐照的内皮细胞培养基补充 ecDNA(R)，并沿着一系列参数（旁观者效应）分析细胞。暴露细胞和旁观者内皮细胞对低剂量表现出相似的反应：1 号染色体 1q12 位的染色体片段接近，并转移到细胞核内，内皮细胞核形状发生变化，核仁组织区（NORs）激活，肌动蛋白聚合，以及 DNA 双链断裂水平升高。在旁观者细胞中用寡核苷酸抑制剂或氯喹阻断 TLR9 受体后，这些效应——除了 NORs 的激活——在暴露于 ecDNA(R)时消失，因此没有观察到旁观者反应。在研究旁观者效应中的辐射诱导细胞凋亡的存在表明，辐射诱导的 ecDNA 片段（即应激信号因子）可能被释放到培养基中，而 TLR9 的抑制表明这些配体与受体细胞结合。我们之前在人淋巴细胞中描述了旁观者效应中的类似 DNA 信号通路。数据的完整性使得我们可以假设，我们在淋巴细胞（体液系统）中证明的类似信号机制，也可能在旁观者效应发展后，通过培养基传递应激信号因子（ecDNA(R)），在单层细胞培养物（细胞组织）中介导。
