53BP1 Oligomerization is Independent of its Methylation by PRMT1

Adams, Melissa M.; Wang, Bin; Xia, Zuo‐Li; Morales, Julio C.; Lu, Xiongbin; Donehower, Lawrence A.; Bochar, Daniel A.; Elledge, Stephen J.; Carpenter, Phillip B.

doi:10.4161/cc.4.12.2282

Cited by 66 publications

(61 citation statements)

References 28 publications

(53 reference statements)

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“…The region required for oligomerization in vivo maps to residues 1052 to 1475, which includes the region we identified above as being critical for focus formation (2). Because coimmunoprecipitation of 53BP1 proteins with different tags could indicate binding of multiple 53BP1 molecules to some third entity (for example, chromatin) and not necessarily homo-oligomerization, we examined whether 53BP1 contains a homo-oligomerization domain by using an in vitro biochemical assay.…”

Section: Resultsmentioning

confidence: 99%

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An Oligomerized 53BP1 Tudor Domain Suffices for Recognition of DNA Double-Strand Breaks

Zgheib

Pataky

Brugger

et al. 2009

Molecular and Cellular Biology

105

111

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53BP1, the vertebrate ortholog of the budding yeast Rad9 and fission yeast Crb2/Rhp9 checkpoint proteins, is recruited rapidly to sites of DNA double-strand breaks (DSBs). A tandem tudor domain in human 53BP1 that recognizes methylated residues in the histone core is necessary, but not sufficient, for efficient recruitment. By analysis of deletion mutants, we identify here additional elements in 53BP1 that facilitate recognition of DNA DSBs. The first element corresponds to an independently folding oligomerization domain. Replacement of this domain with heterologous tetramerization domains preserves the ability of 53BP1 to recognize DNA DSBs. A second element is only about 15 amino acids long and appears to be a C-terminal extension of the tudor domain, rather than an independently functioning domain. Recruitment of 53BP1 to sites of DNA DSBs is facilitated by histone H2AX phosphorylation and ubiquitination. However, none of the 53BP1 domains/ elements important for recruitment are known to bind phosphopeptides or ubiquitin, suggesting that histone phosphorylation and ubiquitination regulate 53BP1 recruitment to sites of DNA DSBs indirectly.Monitoring the presence of DNA double-strand breaks (DSBs) is critical for maintaining genomic stability. In eukaryotes, the DNA DSB checkpoint pathway senses the presence of DNA DSBs and activates effectors that induce cell cycle arrest, apoptosis, or senescence. Key components of this pathway in human cells are DNA DSB sensors such as 53BP1 and the Mre11-Rad50-NBS1 complex, the signal transducing kinase ATM, and effectors downstream of ATM such as the kinase Chk2 and the transcription factor p53 (1,16,25).53BP1 is one of the DNA damage response proteins that is recruited very efficiently to sites of DNA DSBs. Its recruitment can be visualized either by immunofluorescence of fixed cells or by monitoring live cells expressing 53BP1 fused to green fluorescent protein (GFP). In cells exposed to ionizing radiation (IR), the recruitment of 53BP1 to sites of DNA DSBs becomes evident by its localization to foci that are distributed throughout the nucleus; these foci are thought to correspond to sites of DNA DSBs (4,20,30,33,44). When DNA damage is induced in specific subnuclear compartments, for example, by UV laser light or by highly charged energetic particles, then 53BP1 localizes to the subnuclear compartments, where the DNA damage was induced (5, 8).The ability to easily monitor recruitment of 53BP1 to sites of DNA DSBs has allowed significant progress to be made regarding how this protein recognizes DNA damage. Mammalian 53BP1 and its orthologs Rad9 and Crb2/Rhp9, in budding and fission yeast, respectively, recognize DNA DSBs via a tandem tudor domain that binds to methylated histones (18, 31). Human 53BP1 recognizes either methylated K79 of histone H3 or methylated K20 of histone H4 (6,18,32,46), Rad9 recognizes exclusively methylated K79 of histone H3 (13, 43), and Crb2/Rhp9 recognizes exclusively methylated K20 of histone H4 (10, 31). Both K79 of histone H3 and K20 of hist...

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Section: Resultsmentioning

confidence: 99%

“…Using this assay, the oligomerization domain was mapped within residues 1052 to 1475 (2). A subsequent study further refined the boundaries of the oligomerization domain to residues 1231 to 1270 but paradoxically also reported that this domain was not required for 53BP1 focus formation (41).…”

Section: Discussionmentioning

confidence: 99%

An Oligomerized 53BP1 Tudor Domain Suffices for Recognition of DNA Double-Strand Breaks

Zgheib

Pataky

Brugger

et al. 2009

Molecular and Cellular Biology

105

111

View full text Add to dashboard Cite

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“…53BP1 has recently been shown to homo-oligomerize in a DNA damage-independent manner. The region required and sufficient for oligomerization has been mapped to residues 1052-1475, an area upstream of the 53BP1 tandem Tudor folds (27). To gain further insight into the function of 53BP1 oligomerization, we attempted to narrow down the region using nuclear magnetic resonance (NMR) spectroscopy.…”

Section: Resultsmentioning

confidence: 99%

The Tandem BRCT Domain of 53BP1 Is Not Required for Its Repair Function

Ward

Kim

Minn

et al. 2006

Journal of Biological Chemistry

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53BP1 plays an important role in cellular response to DNA damage. It is thought to be the mammalian homologue of budding yeast Rad9 and/or fission yeast Crb2. Rad9/Crb2 are bona fide checkpoint proteins whose activation requires their corresponding C-terminal tandem BRCT (BRCA1 C-terminal) motifs, which mediate their oligomerization and phosphorylation at multiple sites following DNA damage. Here we show that the function of human 53BP1 similarly depends on its oligomerization and phosphorylation at multiple sites but in a BRCT domain-independent manner. Moreover, unlike its proposed yeast counterparts, human 53BP1 only has limited checkpoint functions but rather acts as an adaptor in the repair of DNA double strand breaks. This difference in function may reflect the higher complexity of the DNA damage response network in metazoa including the evolution of other BRCT domain-containing proteins that may have functions redundant or overlapping with those of 53BP1.To protect the integrity of their DNA against the potentially deleterious assaults from various endogenous and environmental sources, cells have evolved a genome surveillance network that carefully coordinates DNA repair with cell cycle progression. DNA double strand breaks (DSBs) 4 are considered the most toxic type of DNA damage. If left unrepaired or repaired improperly, they cause chromosomal aberrations, which may be lethal or result in oncogenic transformation (1, 2). One of the network components activated early in response to DNA DSBs is 53BP1, a large nuclear protein that was originally identified in a yeast two-hybrid screen as a p53-binding partner (3). Domain analysis revealed the presence of a tandem BRCT motif at the C terminus of 53BP1, a domain frequently found in proteins implicated in DNA damage response pathways (4, 5). Moreover, the N terminus of 53BP1 contains several (S/T)Q motifs, the preferred phosphorylation sites for members of the phosphoinositide 3-kinase-related protein kinase (PIKK) family, which play central roles in DNA damage signal transduction. Subsequent studies showed that 53BP1 is phosphorylated by the PIKK family member ATM and undergoes a rapid relocalization to sites of DNA DSBs upon exposure of cells to DNAdamaging agents (6 -9). Mice deficient for 53BP1 show increased radiation sensitivity and an elevated tumor risk (10, 11). Moreover, class switch recombination of immunoglobulin heavy chains is severely impaired in the absence of 53BP1, suggesting a defect in the non-homologous end-joining of DNA DSBs (12, 13).The repair defect in 53BP1-deficient cells can be quantified by assessing PIKK-dependent phosphorylation of the histone H2A variant, H2AX, a component of the nucleosome core structure (14,15). In response to DNA damage, H2AX is reversibly phosphorylated at megabase regions flanking the sites of DNA DSBs (16). Once repair has been completed, the histone mark is removed from the chromatin with the help of protein phosphatase 2A (17, 18).Previous studies showed that relocalization of 53BP1 to the sites of D...

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“…In addition, because 53BP1 is required for recruiting both BLM and p53 to stalled replication forks (32), defects in this H2AX-independent mechanism could contribute to increased genomic instability and tumorigenesis. In this light, it is interesting to note that 53BP1, like p53 and BLM, displays a ''hyper-rec'' phenotype (33). The T cells examined from 53BP1 Ϫ/Ϫ ͞p53 Ϫ/Ϫ thymic lymphomas developed into and through the DP stage and appear to have properly executed V(D)J recombination.…”

Section: Discussionmentioning

confidence: 99%

53BP1 and p53 synergize to suppress genomic instability and lymphomagenesis

Morales

Franco

Murphy

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

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p53-binding protein 1 (53BP1) participates in the cellular response to DNA double-stranded breaks where it associates with various DNA repair͞cell cycle factors including the H2AX histone variant. Mice deficient for 53BP1 (53BP1 ؊/؊ ) are sensitive to ionizing radiation and immunodeficient because of impaired Ig heavy chain class switch recombination. Here we show that, as compared with p53 ؊/؊ mice, 53BP1 ؊/؊ ͞p53 ؊/؊ animals more rapidly develop tumors, including T cell lymphomas and, at lower frequency, B lineage lymphomas, sarcomas, and teratomas. In addition, T cells from animals deficient for both 53BP1 and p53 (53BP1 ؊/؊ ͞p53 ؊/؊ ) display elevated levels of genomic instability relative to T cells deficient for either 53BP1 or p53 alone. In contrast to p53 ؊/؊ T cell lymphomas, which routinely display aneuploidy but not translocations, 53BP1 ؊/؊ ͞p53 ؊/؊ thymic lymphomas fall into two distinct cytogenetic categories, with many harboring clonal translocations (40%) and the remainder showing aneuploidy (60%). We propose that 53BP1, in the context of p53 deficiency, suppresses T cell lymphomagenesis through its roles in both cell-cycle checkpoints and double-stranded break repair.thymic lymphoma ͉ aneuploidy ͉ translocations D ouble-stranded break (DSB) repair is essential for genomic stability and tumor suppression. In mammalian cells, DSBs arise through exogenous means such as ionizing radiation, at stalled replication forks, and in the context of two genetically programmed processes that occur in lymphoid cells (1-3). DSBs are repaired by either of two nonmutually exclusive mechanisms: homologous recombination and nonhomologous end joining. During the development of the immune system, both B and T cells assemble the exons that encode Igs and T cell receptor variable regions by means of V(D)J recombination. In addition, mature B cells can express different Ig heavy chain constant regions through a DSB-mediated process known as Ig heavy chain class switch recombination (CSR). The DSBs that initiate V(D)J recombination are generated by the site-specific RAG endonuclease, whereas those that initiate CSR appear to involve the activation-induced deaminase. However, both V(D)J recombination and CSR are completed by nonhomologous end joining. In contrast to V(D)J recombination, CSR requires components of the DNA DSB repair response, including the histone variant H2AX and p53 binding protein 1 (53BP1) (4-7), potentially to juxtapose broken DSBs for nonhomologous end joining (8). Although 53BP1 is required for joining of S regions during CSR, like H2AX, it does not appear to be absolutely required for V(D)J recombination (6, 7), perhaps because of the fact that RAG also mediates synapsis functions (8).53BP1 is phosphorylated in response to ionizing radiation, accumulates at or near sites of DNA damage, and participates in the intra S and G 2 ͞M checkpoints (reviewed in ref. 9). Accumulation of 53BP1 at sites of irradiation-induced foci depends on

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53BP1 Oligomerization is Independent of its Methylation by PRMT1

Cited by 66 publications

References 28 publications

An Oligomerized 53BP1 Tudor Domain Suffices for Recognition of DNA Double-Strand Breaks

An Oligomerized 53BP1 Tudor Domain Suffices for Recognition of DNA Double-Strand Breaks

The Tandem BRCT Domain of 53BP1 Is Not Required for Its Repair Function

53BP1 and p53 synergize to suppress genomic instability and lymphomagenesis

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