Replicated chromatin curtails 53BP1 recruitment in BRCA1-proficient and BRCA1-deficient cells

Mitxelena, Jone; Pellegrino, Stefania; Spegg, Vincent; Altmeyer, Matthias

doi:10.26508/lsa.202101023

Cited by 16 publications

(19 citation statements)

References 49 publications

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“…Considering that IR does not only cause DSB but also other lesions including oxidative base damage, single strand breaks, fragmented sugar derivatives and loss of terminal base residues culminating in clustered damage or single stranded gaps [ 27 ], we speculate that the γH2AX foci observed at later time points in young men might represent secondary DSB that arise after fork stalling at these IR-induced lesions. Intriguingly, 53BP1 recruitment to DSB is suppressed in replicating chromatin [ 73 ], which could explain why only an accumulation of γH2AX but not 53BP1 foci could be observed. Therefore, unresolved γH2AX foci in young men might reflect DNA lesions and replication intermediates rather than clean DSB such as generated by I-SceI in reporter-based assays, which warrants in-depth analysis in future studies.…”

Section: Discussionmentioning

confidence: 99%

Sex-specific differences in DNA double-strand break repair of cycling human lymphocytes during aging

Rall-Scharpf

Friedl

Biechonski

et al. 2021

Aging

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The gender gap in life expectancy and cancer incidence suggests differences in the aging process between the sexes. Genomic instability has been recognized as a key factor in aging, but little is known about sex-specific differences. Therefore, we analyzed DNA double-strand break (DSB) repair in cycling human peripheral blood lymphocytes (PBL) from male and female donors of different age. Reporter-based DSB repair analyses revealed differential regulation of pathway usage in PBL from male and female donors with age: Non-homologous end joining (NHEJ) was inversely regulated in men and women; the activity of pathways requiring end processing and strand annealing steps such as microhomology-mediated end joining (MMEJ) declined with age in women but not in men. Screening candidate proteins identified the NHEJ protein KU70 as well as the end resection regulatory factors ATM and BLM showing reduced expression during aging in women. Consistently, the regulatory factor BLM contributed to the MMEJ proficiency in young but not in old women as demonstrated by knockdown analysis. In conclusion, we show that DSB repair is subject to changes upon aging and age-related changes in DSB repair are distinct in men and women.

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Section: Discussionmentioning

confidence: 99%

Sex-specific differences in DNA double-strand break repair of cycling human lymphocytes during aging

Rall-Scharpf

Friedl

Biechonski

et al. 2021

Aging

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“…53BP1 and BRCA1 play a critical role in the cell cycle-dependent regulation of DNA repair. 53BP1 is often used interchangeably with histone H2AX phosphorylation to enumerate DSBs despite cell cycle-dependent relationships on 53BP1 foci abundance being reported ( Escribano-Díaz et al, 2013 ; Feng et al, 2015 ; Michelena et al, 2021 ; Swift et al, 2021 ). We sought to assess the heterogeneity in their association with sites of DNA DSBs within asynchronous cell populations.…”

Section: Resultsmentioning

confidence: 99%

“…Thus, we would predict that in early S phase, where 53BP1 foci are prominent, they will localize to unreplicated DNA, and the replicated chromatin will be refractory to 53BP1 assembly. Although this epigenetic change has been shown to reduce 53BP1 occupancy in the presence or absence of BRCA1, these epigenetic differences may not be sufficient to prevent the binding of 53BP1 to newly replicated DNA in S phase ( Michelena et al, 2021 ). Figure 3A shows the relationship between EdU incorporation, BRCA1, and 53BP1 in an early S-phase nucleus.…”

Section: Resultsmentioning

confidence: 99%

“…Super-resolution studies of DNA DSBs reveal that individual classes of proteins are not homogeneously distributed throughout the focus ( Reindl et al, 2017 , 2022 ; Schwarz et al, 2019 ; Michelena et al, 2021 ). For example, BRCA1 and 53BP1 occupy distinct regions of the compartment ( Chapman et al, 2012 ; Mok and Henderson, 2012 ; Schwarz et al, 2019 ).…”

Section: Resultsmentioning

confidence: 99%

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Heterogeneity of Organization of Subcompartments in DSB Repair Foci

Abate

Hendzel

2022

Front. Genet.

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Cells assemble compartments around DNA double-strand breaks (DSBs). The assembly of this compartment is dependent on the phosphorylation of histone H2AX, the binding of MDC1 to phosphorylated H2AX, and the assembly of downstream signaling and repair components. The decision on whether to use homologous recombination or nonhomologous end-joining repair depends on competition between 53BP1 and BRCA1. A major point of control appears to be DNA replication and associated changes in the epigenetic state. This includes dilution of histone H4 dimethylation and an increase in acetylation of lysine residues on H2A and H4 that impair 53BP1 binding. In this article, we examined more closely the spatial relationship between 53BP1 and BRCA1 within the cell cycle. We find that 53BP1 can associate with early S-phase replicated chromatin and that the relative concentration of BRCA1 in DSB-associated compartments correlates with increased BRCA1 nuclear abundance as cells progress into and through S phase. In most cases during S phase, both BRCA1 and 53BP1 are recruited to these compartments. This occurs for both IR-induced DSBs and breaks targeted to an integrated LacO array through a LacI-Fok1-mCherry fusion protein. Having established that the array system replicates this heterogeneity, we further examined the spatial relationship between DNA repair components. This enabled us to precisely locate the DNA containing the break and map other proteins relative to that DNA. We find evidence for at least three subcompartments. The damaged DNA, single-stranded DNA generated from end resection of the array, and nuclease CtIP all localized to the center of the compartment. BRCA1 and 53BP1 largely occupied discrete regions of the focus. One of BRCA1 or 53BP1 overlaps with the array, while the other is more peripherally located. The array-overlapping protein occupied a larger volume than the array, CtIP, or single-stranded DNA (ssDNA). Rad51 often occupied a much larger volume than the array itself and was sometimes observed to be depleted in the array volume where the ssDNA exclusively localizes. These results highlight the complexity of molecular compartmentalization within DSB repair compartments.

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“…H4K20me0 specifically marks replicated chromatin and thereby targets BARD1‐BRCA1 to those areas of the genome, where a replicated template is available for HR repair. Replicated chromatin not only serves as a binding platform for BARD1‐BRCA1, but is also refractory to the binding of the resection antagonist 53BP1 (Michelena et al , 2021 ), which through its tandem Tudor domain interacts with H4K20me2 but not with H4K20me0.…”

mentioning

confidence: 99%

When the RAP (80) fades out, you can hear BRCA1 RING

Παναγόπουλος

Altmeyer

2021

EMBO Reports

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The tumor suppressor protein BRCA1 plays an important role in DNA repair by homologous recombination. Despite being encoded by the first familial breast and ovarian cancer gene identified, how BRCA1 is recruited to sites of DNA damage to execute its repair functions has remained poorly understood. Several recent studies highlight the role of its constitutive interaction partner BARD1 in this process. In this issue, parallel work by Sherker et al (2021) focused on a second route of BRCA1 recruitment, connected to the BRCA1‐A complex protein RAP80. Studying BRCA1 recruitment in RAP80‐deficient cells exposed a critical role for the BRCA1 RING domain and its associated ubiquitin ligase activity. Given that tumors expressing RING‐less BRCA1 isoforms can become resistant to therapy, targeting the RAP80 recruitment axis in such tumors might restore effective treatment.

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Replicated chromatin curtails 53BP1 recruitment in BRCA1-proficient and BRCA1-deficient cells

Cited by 16 publications

References 49 publications

Sex-specific differences in DNA double-strand break repair of cycling human lymphocytes during aging

Sex-specific differences in DNA double-strand break repair of cycling human lymphocytes during aging

Heterogeneity of Organization of Subcompartments in DSB Repair Foci

When the RAP (80) fades out, you can hear BRCA1 RING

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