Phosphorylation of SDT repeats in the MDC1 N terminus triggers retention of NBS1 at the DNA damage–modified chromatin

Melander, Fredrik; Bekker‐Jensen, Simon; Falck, Jacob; Bártek, Jiří; Mailand, Niels; Lukáš, Jiří

doi:10.1083/jcb.200708210

Cited by 205 publications

(196 citation statements)

References 51 publications

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“…While this work was under review, three related papers were published (35)(36)(37). These studies agree with our conclusion and support a role of MDC1/NBS1 interaction in DNA damage checkpoint control.…”

Section: Identification Of Mdc1 Phosphorylation Sites By Mass Spectrosupporting

confidence: 80%

MDC1 regulates intra-S-phase checkpoint by targeting NBS1 to DNA double-strand breaks

Luo

Lou

et al. 2008

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

144

145

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The product of the Nijmegen breakage syndrome gene (NBS1) plays crucial roles in DNA damage response through its association with many proteins, including MRE11 and RAD50. However, it remains to be determined exactly how NBS1 accumulates at or near DNA double-strand breaks. Here we report that MDC1 directly binds to NBS1 and targets NBS1 to the sites of DNA damage. The MDC1-NBS1 interaction occurs through a specific region (residues 200 -420) of MDC1, which contains multiple consensus casein kinase 2 (CK2) phosphorylation sites. In addition, this interaction requires both the forkhead-associated (FHA) and tandem BRCA1 C-terminal (BRCT) domains of NBS1. Disruption of the MDC1-NBS1 interaction results in failure of NBS1 accumulation at DNA doublestrand breaks and impairment of intra-S checkpoint activation. These studies provide important mechanistic insights as to how MDC1 regulates NBS1 and the intra-S-phase checkpoint in response to DNA damage.complex plays important roles in cell cycle checkpoint signaling and DNA repair. Hypomorphic mutations in NBS1 and MRE11 cause Nijmegen breakage syndrome (NBS) and ataxiatelangiectasia-like disorder (ATLD) respectively (1-3), characterized by developmental defects, immunodeficiency, and a high incidence of cancer. Cells derived from NBS and ATLD patients are hypersensitive to radiation and display impaired intra-Sphase checkpoint activation (1-3), supporting critical roles of this complex in DNA damage response.In response to DNA damage, the MRE11/RAD50/NBS1 complex regulates the activation of ATM, the protein kinase essential for the DNA damage signaling. The key component involved in ATM activation is believed to be NBS1, because NBS1 directly binds to ATM through a very C-terminal motif and modulates ATM autophosphorylation (4-7). Biochemical evidence also suggests that the MRN complex recruits ATM to the vicinity of DNA double-strand breaks (DSBs) and stimulates ATM activation (8). In addition to playing a role in ATM activation, NBS1 also functions downstream of ATM in regulating the intra-S-phase checkpoint (9-11). Besides regulating ATM-dependent phosphorylation of SMC proteins (12, 13), the mechanism by which NBS1 participates in this intra-S-phase checkpoint remains elusive.The human NBS1 gene encodes a 754-aa nuclear protein with an N-terminal forkhead-associated (FHA) domain and breast cancer BRCA1 C-terminal (BRCT) domain. Recently, a second BRCT domain (termed BRCT2) has been identified adjacent to the first BRCT domain (termed BRCT1) (14). Both FHA and BRCT domains mediate protein-protein interaction by recognizing phosphoserine (pSer) and phosphothreonine (pThr)-containing motifs, and many proteins involved in the DNA damage responses contain functional FHA and BRCT domains. Previous reports indicate that retention of NBS1 at DSBs, after DNA damage, is mediated by its interaction with MDC1 (15-19). Moreover, the FHA and BRCT domains of NBS1 are required for its recruitment to DSBs (nuclear foci) after DNA damage (20)(21)(22). Despite these results, it is st...

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Section: Identification Of Mdc1 Phosphorylation Sites By Mass Spectrosupporting

confidence: 80%

MDC1 regulates intra-S-phase checkpoint by targeting NBS1 to DNA double-strand breaks

Luo

Lou

et al. 2008

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

144

145

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“…The mechanism by which MDC1 regulates NBS1 retention at DSBs was poorly understood until recent independent reports by four groups which demonstrated that MDC1 directly binds NBS1. [61][62][63][64] Since NBS1 also binds ATM, 29 these results suggest that MDC1 can recruit multiple ATM molecules to DSBs, both directly through its FHA domain as well as indirectly through NBS1, thus allowing a more efficient and quick positive feedback loop (Fig. 1D).…”

mentioning

confidence: 97%

“…Similar results were obtained when mutations or deletions were introduced in either the SDT repeats of MDC1 or the FHA-tBRCT domains of NBS1. [61][62][63][64] Interesting questions arise from the data discussed above. Why does MDC1 contain multiple SDT repeats?…”

mentioning

confidence: 99%

“…61 However, progressively mutating more serine and threonine residues of the SDT repeats led to gradually lower affinity of MDC1 to NBS1 and to impaired redistribution of NBS1 to foci, suggesting that the existence of multiple SDT repeats in MDC1 allows cooperative and/or redundant binding to NBS1. 62,63 Another interesting issue is the unique mode of binding between the FHA and tBRCT domains of NBS1 and the phospho-SDT motif of MDC1. FHA and tBRCT domains can each mediate protein-protein interactions on their own, showing specificity for pThr or pSer, respectively (see box 2).…”

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confidence: 99%

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The cellular response to DNA damage: A focus on MDC1 and its interacting proteins

Coster

Goldberg

2010

nucleus

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“…The mediator of DNA-damage checkpoint 1 (MDC1) is another binding partner of NBS1. When MDC1 is phosphorylated by casein kinase 2, it can interact with the FHA domain of NBS1, and this interaction may be important for the accumulation of NBS1 at DSB sites (Chapman and Jackson, 2008;Melander et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Chromatin modification and NBS1: their relationship in DNA double-strand break repair

2015

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The importance of chromatin modification, including histone modification and chromatin remodeling, for DNA double-strand break (DSB) repair, as well as transcription and replication, has been elucidated. Phosphorylation of H2AX to γ-H2AX is one of the first responses following DSB detection, and this histone modification is important for the DSB damage response by triggering several events, including the accumulation of DNA damage response-related proteins and subsequent homologous recombination (HR) repair. The roles of other histone modifications such as acetylation, methylation and ubiquitination have also been recently clarified, particularly in the context of HR repair. NBS1 is a multifunctional protein that is involved in various DNA damage responses. Its recently identified binding partner RNF20 is an E3 ubiquitin ligase that facilitates the monoubiquitination of histone H2B, a process that is crucial for recruitment of the chromatin remodeler SNF2h to DSB damage sites. Evidence suggests that SNF2h functions in HR repair, probably through regulation of end-resection. Moreover, several recent reports have indicated that SNF2h can function in HR repair pathways as a histone remodeler and that other known histone remodelers can also participate in DSB damage responses. On the other hand, information about the roles of such chromatin modifications and NBS1 in non-homologous end joining (NHEJ) repair of DSBs and stalled fork-related damage responses is very limited; therefore, these aspects and processes need to be further studied to advance our understanding of the mechanisms and molecular players involved.

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Phosphorylation of SDT repeats in the MDC1 N terminus triggers retention of NBS1 at the DNA damage–modified chromatin

Cited by 205 publications

References 51 publications

MDC1 regulates intra-S-phase checkpoint by targeting NBS1 to DNA double-strand breaks

MDC1 regulates intra-S-phase checkpoint by targeting NBS1 to DNA double-strand breaks

The cellular response to DNA damage: A focus on MDC1 and its interacting proteins

Chromatin modification and NBS1: their relationship in DNA double-strand break repair

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