Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany.
Bavarian Health and Food Safety Authority, Erlangen, Germany.
Arch Toxicol. 2023 Mar;97(3):875-889. doi: 10.1007/s00204-022-03433-9. Epub 2022 Dec 23.
Although micronuclei are well-known biomarkers of genotoxic damage, the biological consequences of micronucleus induction are only poorly understood. To further elucidate these consequences, HeLa cells stably expressing histone 2B coupled with green fluorescent protein were used for long-term live cell imaging to investigate the fate of micronuclei and micronucleated cells after treatment of cells with various genotoxic agents (doxorubicin (20, 30 and nM), tert-butyl hydroperoxide (tBHP, 50, 100 and 150 µM), radiation (0.5, 1 and 2 Gy), methyl methanesulfonate (MMS, 20, 25 and 30 µg/ml) and vinblastine (1, 2 and 3 nM)). Most micronuclei persist for multiple cell cycles or reincorporate while micronucleated cells were more prone to cell death, senescence and fatal mitotic errors compared to non-micronucleated cells, which is consistent with previous studies using etoposide. No clear substance-related effects on the fate of micronuclei and micronucleated cells were observed. To further investigate the fate of micronuclei, extrusion of micronuclei was studied with treatments reported as inducing the extrusion of micronuclei. Since extrusion was not observed in HeLa cells, the relevance of extrusion of micronuclei remains unclear. In addition, degradation of micronuclei was analysed via immunostaining of γH2AX, which demonstrated a high level of DNA damage in micronuclei compared to the main nuclei. Furthermore, transduction with two reporter genes (LC3B-dsRed and LaminB1-dsRed) was conducted followed by long-term live cell imaging. While autophagy marker LC3B was not associated with micronuclei, Lamin B1 was found in approximately 50% of all micronuclei. While degradation of micronuclei was not observed to be a frequent fate of micronuclei, the results show impaired stability of DNA and micronuclear envelope indicating rupture of micronuclei as a pre-step to chromothripsis.
虽然微核是遗传毒性损伤的众所周知的生物标志物,但微核诱导的生物学后果知之甚少。为了进一步阐明这些后果,使用稳定表达组蛋白 2B 与绿色荧光蛋白的 HeLa 细胞进行长期活细胞成像,以研究在用各种遗传毒性剂(阿霉素(20、30 和 nM)、叔丁基过氧化物(tBHP,50、100 和 150 µM)、辐射(0.5、1 和 2 Gy)、甲磺酸甲酯(MMS,20、25 和 30 µg/ml)和长春碱(1、2 和 3 nM))处理细胞后微核和微核细胞的命运。大多数微核在多个细胞周期中持续存在或重新掺入,而与非微核细胞相比,微核细胞更容易死亡、衰老和发生致命的有丝分裂错误,这与以前使用依托泊苷的研究结果一致。没有观察到与微核和微核细胞的命运相关的明显物质相关效应。为了进一步研究微核的命运,研究了用报道可诱导微核挤出的处理方法挤出微核。由于在 HeLa 细胞中未观察到挤出,因此微核挤出的相关性仍不清楚。此外,通过 γH2AX 的免疫染色分析了微核的降解,与主核相比,微核显示出高水平的 DNA 损伤。此外,进行了两个报告基因(LC3B-dsRed 和 LaminB1-dsRed)的转导,然后进行长期活细胞成像。虽然自噬标志物 LC3B 与微核无关,但在大约 50%的所有微核中发现了 Lamin B1。虽然微核的降解不是微核的常见命运,但结果表明 DNA 和微核包膜的稳定性受损,表明微核破裂是染色体重排的前一步。