53BP1 nuclear bodies form around DNA lesions generated by mitotic transmission of chomosomes under replication stress

Centre for Genotoxic Stress Research, Institute of Cancer Biology, Danish Cancer Society, Strandboulevarden 49, DK-2100 Copenhagen, Denmark.
Nature Cell Biology (Impact Factor: 19.68). 02/2011; 13(3):243-53. DOI: 10.1038/ncb2201
Source: PubMed


Completion of genome duplication is challenged by structural and topological barriers that impede progression of replication forks. Although this can seriously undermine genome integrity, the fate of DNA with unresolved replication intermediates is not known. Here, we show that mild replication stress increases the frequency of chromosomal lesions that are transmitted to daughter cells. Throughout G1, these lesions are sequestered in nuclear compartments marked by p53-binding protein 1 (53BP1) and other chromatin-associated genome caretakers. We show that the number of such 53BP1 nuclear bodies increases after genetic ablation of BLM, a DNA helicase associated with dissolution of entangled DNA. Conversely, 53BP1 nuclear bodies are partially suppressed by knocking down SMC2, a condensin subunit required for mechanical stability of mitotic chromosomes. Finally, we provide evidence that 53BP1 nuclear bodies shield chromosomal fragile sites sequestered in these compartments against erosion. Together, these data indicate that restoration of DNA or chromatin integrity at loci prone to replication problems requires mitotic transmission to the next cell generations.

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Available from: Velibor Savic
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    • "Interestingly, the number of 53BP1-positive NBs can increase after experimental intervention on the DNA helicase BLM, whereas 53BP1 NB formation can be reduced by depletion of the condensin subunit SMC2 (Lukas et al., 2011). Intriguingly, the nuclear distribution patterns of 53BP1 NBs are identical in sister cells (Lukas et al., 2011). From these results, however, the function and formation of repair foci still remain elusive. "
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    ABSTRACT: Background information: The DNA damage response is a fundamental, well-regulated process that occurs in the genome to recognize DNA lesions. Here, we studied kinetics of proteins involved in DNA repair pathways and their recruitment to DNA lesions during the cell cycle. In non-irradiated and irradiated cells, we analyzed the distribution pattern and spatiotemporal dynamics of γH2AX, 53BP1, BMI1, MDC1, NBS1, PCNA, coilin and BRCA1 proteins. Results: We observed that spontaneous and irradiation-induced foci (IRIF) demonstrated a high abundance of phosphorylated H2AX, which was consistent with 53BP1 and BMI1 protein accumulation. However, NBS1 and MDC1 proteins were recruited to nuclear bodies (NBs) to a lesser extent. Irradiation by γ-rays significantly increased the number of 53BP1- and γH2AX-positive IRIF, but cell cycle-dependent differences were only observed for γH2AX-positive foci in both non-irradiated and γ-irradiated cells. In non-irradiated cells, the G2 phase was characterized by an increased number of spontaneous γH2AX-foci; this increase was more pronounced after γ-irradiation. Cells in G2 phase had the highest number of γH2AX-positive foci. Similarly, γ-irradiation increased the number of NBS1-positive nuclear bodies only in G2 phase. Moreover, NBS1 accumulated in nucleoli after γ-irradiation showed the slowest recovery after photobleaching. Analysis of protein accumulation kinetics at locally induced DNA lesions showed that in HeLa cells, BMI1, PCNA and coilin were rapidly recruited to the lesions, 10-15 s after UVA-irradiation, while among the other proteins studied, BRCA1 demonstrated the slowest recruitment: BRCA1 appeared at the lesion 20 min after local micro-irradiation by UVA laser. Conclusion: We show that the kinetics of the accumulation of selected DNA repair-related proteins is protein-specific at locally induced DNA lesions, and that the formation of γH2AX- and NBS1-positive foci, but not 53BP1-positive nuclear bodies, is cell cycle-dependent in HeLa cells. Moreover, γH2AX is the most striking protein present not only at DNA lesions, but also spreading out in their vicinity. Our conclusions highlight the significant role of the spatiotemporal dynamics of DNA repair-related proteins and their specific assembly/disassembly at DNA lesions, which can be cell type- and cell cycle-dependent. This article is protected by copyright. All rights reserved.
    Full-text · Article · Oct 2015 · Biology of the Cell
    • "See also Figure S1. These can lead to chromosome breakage and packaging of the damaged DNA into 53BP1 bodies visible in the subsequent G1 phase (Lukas et al., 2011). We next determined the prevalence of late replicating DNA, UFBs, and G1-phase 53BP1 bodies in BOD1L-deficient cells following MMC exposure. "
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    ABSTRACT: Recognition and repair of damaged replication forks are essential to maintain genome stability and are coordinated by the combined action of the Fanconi anemia and homologous recombination pathways. These pathways are vital to protect stalled replication forks from uncontrolled nucleolytic activity, which otherwise causes irreparable genomic damage. Here, we identify BOD1L as a component of this fork protection pathway, which safeguards genome stability after replication stress. Loss of BOD1L confers exquisite cellular sensitivity to replication stress and uncontrolled resection of damaged replication forks, due to a failure to stabilize RAD51 at these forks. Blocking DNA2-dependent resection, or downregulation of the helicases BLM and FBH1, suppresses both catastrophic fork processing and the accumulation of chromosomal damage in BOD1L-deficient cells. Thus, our work implicates BOD1L as a critical regulator of genome integrity that restrains nucleolytic degradation of damaged replication forks. Copyright © 2015 Elsevier Inc. All rights reserved.
    No preview · Article · Jul 2015 · Molecular cell
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    • "Surveillance of genomic DNA in newly formed nuclei has been described as a G1 event (Harrigan et al., 2011; Lukas et al., 2011). Our findings here that this process initiates before cytokinetic abscission and influences the timing of abscission integrates well with the recent description of cytokinetic abscission as a G1 event based on tracking cell division with molecular markers (Gershony et al., 2014). "
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    ABSTRACT: Aurora B regulates cytokinesis timing and plays a central role in the abscission checkpoint. Cellular events monitored by this checkpoint are beginning to be elucidated, yet signaling pathways upstream of Aurora B in this context remain poorly understood. Here, we reveal a new connection between postmitotic genome surveillance and cytokinetic abscission. Under-replicated DNA lesions are known to be transmitted through mitosis and protected in newly-formed nuclei by recruitment of 53BP1 and other proteins until repair takes place. We find that this genome surveillance initiates prior to completion of cytokinesis. Elevating replication stress increases this postmitotic process and delays cytokinetic abscission by keeping the abscission checkpoint active. We further find that ATR activity in midbody-stage cells links postmitotic genome surveillance to abscission timing and that Chk1 integrates this and other signals upstream of Aurora B to regulate when the final step in the physical separation of daughter cells occurs. © 2015 by The American Society for Cell Biology.
    Preview · Article · Apr 2015 · Molecular biology of the cell
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