High-LET (Linear Energy Transfer) particle irradiation as being provided from heavy ion accelerator facilities has an increasing impact on bio-medical research and cancer treatment. Nevertheless, there are a lot of open questions concerning the understanding of damaging mechanisms and repair processes within the light of radio-sensitivity and thus, individualized medical applications. The three-dimensional architecture of genomes on the meso- and nano-scale acts in combination with epigenetic gene activation as an important player of gene regulation and fundamental biological processes such as DNA damage response and repair. So far only little is known about the impact of high-LET particles on the chromatin architecture along the passing track when they are “lumbering” through the cell nucleus. How does a cell nucleus manage such complex damages and re-organize the chromatin toward functionally intact units? Is there a radio-sensitivity related difference in this reaction? Here, we present some approaches to investigate spatial and topological parameters of chromatin to glimpse some aspects related to these questions. Two cell lines, a radio-resistant glioblastoma and a radio-sensitive fibroblast cell line, were used and irradiated by ¹⁵N-ions in 90° and 10° radiation beam geometry. Nano-probing of particle induced damage sites along particle tracks, and the recruited DNA repair proteins (as presented here for 53BP1 and Rad51) in combination with super-resolution Single Molecule Localization Microscopy (SMLM) are powerful methods for geometric and topological analyses to study particle related mechanisms of chromatin conformation and repair complexes in single cells. We used variable tools for such investigations based on image free high precision SMLM, nano-scaled molecule distribution analyses, appropriate metrics following Ripley’s distance frequencies and cluster formation analyses, as well as topological quantifications employing persistence homology. The data reveal a cell type specific nano-architecture of DNA damage foci along particle tracks and their dynamic molecular re-arrangements during repair. Comparing the topology of repair foci by persistence homology suggests similarities of repair cluster formation along given particle tracks. Our studies contribute to the molecular understanding of cellular radiation response at sub-light microscopic chromatin levels; thereby showing how chromatin architecture around complex damage sites and repair foci nano-architecture may contribute to ongoing repair processing. The methodological approach presented here may give a basis for improved biological dosimetry or radiotherapies in the future.

由重离子加速器设施提供的高LET（线性能量转移）粒子辐照对生物医学研究和癌症治疗产生越来越大的影响。然而，在放射敏感性和个体化医疗应用的范围内，关于损伤机理和修复过程的理解还有很多悬而未决的问题。介观和纳米尺度的基因组三维结构与表观遗传基因激活相结合，是基因调节和基础生物学过程（如DNA损伤反应和修复）的重要参与者。到目前为止，人们对高LET粒子在通过细胞核“拖延”时沿通过轨迹对染色质结构的影响知之甚少。细胞核如何处理这种复杂的损伤并使染色质重新组成功能完整的单元？此反应中是否存在与放射敏感性相关的差异？在这里，我们提出了一些方法来研究染色质的空间和拓扑参数，以瞥见与这些问题相关的某些方面。使用了两种细胞系，一种抗放射的胶质母细胞瘤和一种对放射敏感性的成纤维细胞，并用放射线照射。¹⁵N离子呈90°和10°辐射束几何形状。纳米探测沿颗粒轨迹的颗粒诱导的损伤位点，以及募集的DNA修复蛋白（如此处针对53BP1和Rad51所述）与超分辨率单分子定位显微镜（SMLM）结合使用，是进行几何和拓扑分析研究的有力方法单细胞中染色质构象和修复复合物的颗粒相关机制。我们使用了基于无图像的高精度SMLM，纳米级分子分布分析，遵循Ripley距离频率和簇形成分析的适当指标以及采用持久性同源性的拓扑量化的可变工具进行此类研究。数据揭示了修复过程中沿着颗粒径迹的DNA损伤灶的特定细胞类型纳米结构及其动态分子重新排列。通过持久性同源性比较修复灶的拓扑结构表明，沿着给定的粒子轨迹修复簇的形成具有相似性。我们的研究有助于在亚光显微染色质水平上对细胞辐射反应的分子理解。从而显示出复杂损伤位点和修复灶纳米结构周围的染色质结构如何有助于正在进行的修复过程。本文介绍的方法学方法可能为将来改进生物剂量学或放射疗法提供基础。通过持久性同源性比较修复灶的拓扑结构表明，沿着给定的粒子轨迹修复簇的形成具有相似性。我们的研究有助于在亚光显微染色质水平上对细胞辐射反应的分子理解。从而显示出复杂损伤位点和修复灶纳米结构周围的染色质结构如何有助于正在进行的修复过程。本文介绍的方法学方法可能为将来改进生物剂量学或放射疗法提供基础。通过持久性同源性比较修复灶的拓扑结构表明，沿着给定的粒子轨迹修复簇的形成具有相似性。我们的研究有助于在亚光显微染色质水平上对细胞辐射反应的分子理解。从而显示出复杂损伤部位和修复灶纳米结构周围的染色质结构如何有助于正在进行的修复过程。本文介绍的方法学方法可能为将来改进生物剂量学或放射疗法提供基础。