Clustering of double strand break-containing chromosome domains is not inhibited by inactivation of major repair proteins

Krawczyk, Przemek M.; Stap, Jan; Oven, Carel van; Hoebe, Ron A.; Aten, Jacob A.

doi:10.1093/rpd/ncl479

Cited by 16 publications

(10 citation statements)

References 12 publications

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“…Live cell experiments with cells stably expressing either GFP-MDC1 or GFP-53BP1 confirmed the transient nature of MDC1 foci formation and the more long-lived nature of 53BP1 assemblies ( Fig 2B). Moreover, and consistent with previous work describing clustering of DNA breaks (Aten et al, 2004;Krawczyk et al, 2006;Neumaier et al, 2012;Roukos et al, 2013;Aymard et al, 2017;Sollazzo et al, 2018), we observed signs of coalescence of 53BP1 compartments over time upon DNA damage ( Fig 3A). Comparing 53BP1 and MDC1 foci intensity and area suggested that this was more pronounced for 53BP1 ( Fig 3A and B, and Appendix Fig S5A).…”

Section: Resultssupporting

confidence: 92%

Phase separation of 53 BP 1 determines liquid‐like behavior of DNA repair compartments

et al. 2019

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The DNA damage response (DDR) generates transient repair compartments to concentrate repair proteins and activate signaling factors. The physicochemical properties of these spatially confined compartments and their function remain poorly understood. Here, we establish, based on live cell microscopy and CRISPR/Cas9‐mediated endogenous protein tagging, that 53BP1‐marked repair compartments are dynamic, show droplet‐like behavior, and undergo frequent fusion and fission events. 53BP1 assembly, but not the upstream accumulation of γH2AX and MDC1, is highly sensitive to changes in osmotic pressure, temperature, salt concentration and to disruption of hydrophobic interactions. Phase separation of 53BP1 is substantiated by optoDroplet experiments, which further allowed dissection of the 53BP1 sequence elements that cooperate for light‐induced clustering. Moreover, we found the tumor suppressor protein p53 to be enriched within 53BP1 optoDroplets, and conditions that disrupt 53BP1 phase separation impair 53BP1‐dependent induction of p53 and diminish p53 target gene expression. We thus suggest that 53BP1 phase separation integrates localized DNA damage recognition and repair factor assembly with global p53‐dependent gene activation and cell fate decisions.

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Section: Resultssupporting

confidence: 92%

Phase separation of 53 BP 1 determines liquid‐like behavior of DNA repair compartments

et al. 2019

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“…These clusters often split and reform, suggesting that they result from random collisions associated with Brownian chromatin motions [21, 25, 37, 66]. However, RIF clusters can also remain merged for an extended period of time [2, 23, 37, 83]. Inelastic collisions leading to clustering suggest the existence of forces that maintain associations between repair sites, likely mediated by bridging proteins.…”

Section: ‘Inelastic Collisions’ Results In the Formation Of Rif Clustementioning

confidence: 99%

“…RIF clustering has been observed in many independent studies [13, 21, 23, 25, 29, 37, 66, 83], and its meaning and consequences remain mostly speculative. One interesting possibility is that RIF clustering could have different functions and consequences in different cell types, cell cycle phases, and chromatin environments.…”

Section: ‘Inelastic Collisions’ Results In the Formation Of Rif Clustementioning

confidence: 99%

Nuclear dynamics of radiation-induced foci in euchromatin and heterochromatin

Chiolo

Tang

Georgescu

et al. 2013

Mutation Research/Fundamental and Molecular Mechanisms of Mutag

105

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Repair of double strand breaks (DSBs) is essential for cell survival and genome integrity. While much is known about the molecular mechanisms involved in DSB repair and checkpoint activation, the roles of nuclear dynamics of radiation-induced foci (RIF) in DNA repair are just beginning to emerge. Here, we summarize results from recent studies that point to distinct features of these dynamics in two different chromatin environments: heterochromatin and euchromatin. We also discuss how nuclear architecture and chromatin components might control these dynamics, and the need of novel quantification methods for a better description and interpretation of these phenomena. These studies are expected to provide new biomarkers for radiation risk and new strategies for cancer detection and treatment.

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“…We next considered the clustering of dysfunctional telomeres as a source of the phenomenon observed. DSBs induced by a variety of treatments have been shown to undergo clustering (Aten et al 2004;Krawczyk et al 2006;Neumaier et al 2012;Cho et al 2014;Mao et al 2016), but the mechanism underlying these associations has not been determined. We argued that if dysfunctional telomeres become clustered, the number of telomeres detected per nucleus should decrease after treatment of the TRF1 F/F TRF2 F/F Lig4 −/− MEFs with Cre.…”

Section: Bp1-dependent Clustering Of Dysfunctional Telomeresmentioning

confidence: 99%

The DDR at telomeres lacking intact shelterin does not require substantial chromatin decompaction

et al. 2017

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Telomeres are protected by shelterin, a six-subunit protein complex that represses the DNA damage response (DDR) at chromosome ends. Extensive data suggest that TRF2 in shelterin remodels telomeres into the t-loop structure, thereby hiding telomere ends from double-stranded break repair and ATM signaling, whereas POT1 represses ATR signaling by excluding RPA. An alternative protection mechanism was suggested recently by which shelterin subunits TRF1, TRF2, and TIN2 mediate telomeric chromatin compaction, which was proposed to minimize access of DDR factors. We performed superresolution imaging of telomeres in mouse cells after conditional deletion of TRF1, TRF2, or both, the latter of which results in the complete loss of shelterin. Upon removal of TRF1 or TRF2, we observed only minor changes in the telomere volume in most of our experiments. Upon codeletion of TRF1 and TRF2, the telomere volume increased by varying amounts, but even those samples exhibiting small changes in telomere volume showed DDR at nearly all telomeres. Upon shelterin removal, telomeres underwent 53BP1-dependent clustering, potentially explaining at least in part the apparent increase in telomere volume. Furthermore, chromatin accessibility, as determined by ATAC-seq (assay for transposase-accessible chromatin [ATAC] with high-throughput sequencing), was not substantially altered by shelterin removal. These results suggest that the DDR induced by shelterin removal does not require substantial telomere decompaction.

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Clustering of double strand break-containing chromosome domains is not inhibited by inactivation of major repair proteins

Cited by 16 publications

References 12 publications

Phase separation of 53 BP 1 determines liquid‐like behavior of DNA repair compartments

Phase separation of 53 BP 1 determines liquid‐like behavior of DNA repair compartments

Nuclear dynamics of radiation-induced foci in euchromatin and heterochromatin

The DDR at telomeres lacking intact shelterin does not require substantial chromatin decompaction

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