The ubiquitin landscape at DNA double-strand breaks

Messick, Troy E.; Greenberg, Roger A.

doi:10.1083/jcb.200908074

Cited by 115 publications

(89 citation statements)

References 84 publications

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“…Given the importance of protein ubiquitination in DDR (21,22), we intended to identify novel Ub genes in DDR and DSB repair through a lentiviral shRNA-based screening with two validated shRNA vectors for each gene. We focused on E2s because of the feasibility of targeting ∼30 genes and included E3 ligases with known roles in DDR (e.g., RNF8 and RNF168, and so forth).…”

Section: Resultsmentioning

confidence: 99%

UbcH7 regulates 53BP1 stability and DSB repair

Han¹,

Zhang²,

Chung³

et al. 2014

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

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DNA double-strand break (DSB) repair is not only key to genome stability but is also an important anticancer target. Through an shRNA library-based screening, we identified ubiquitin-conjugating enzyme H7 (UbcH7, also known as Ube2L3), a ubiquitin E2 enzyme, as a critical player in DSB repair. UbcH7 regulates both the steady-state and replicative stress-induced ubiquitination and proteasome-dependent degradation of the tumor suppressor p53-binding protein 1 (53BP1). Phosphorylation of 53BP1 at the N terminus is involved in the replicative stress-induced 53BP1 degradation. Depletion of UbcH7 stabilizes 53BP1, leading to inhibition of DSB end resection. Therefore, UbcH7-depleted cells display increased nonhomologous end-joining and reduced homologous recombination for DSB repair. Accordingly, UbcH7-depleted cells are sensitive to DNA damage likely because they mainly used the errorprone nonhomologous end-joining pathway to repair DSBs. Our studies reveal a novel layer of regulation of the DSB repair choice and propose an innovative approach to enhance the effect of radiotherapy or chemotherapy through stabilizing 53BP1.DNA damage response | UbcH7 | 53BP1 | protein degradation | DSB repair P rompt response to double-strand breaks (DSBs) caused by, for example, ionization radiation (IR), requires sequential and coordinated assembly of DNA damage response (DDR) proteins at damage sites (1). Recent research findings reveal key roles of the tumor suppressor p53-binding protein 1 (53BP1) and BRCA1 in the decision making of DSB repair. 53BP1, together with Rif1, suppress BRCA1-dependent homologous recombination (HR), thereby promoting nonhomologous end-joining (NHEJ) in G1 phase (2-6). Conversely, BRCA1 antagonizes 53BP1/Rif1, favoring HR in S and G2 phases (7,8). In the absence of BRCA1 or with enhanced retention of 53BP1 at DSB sites, cells primarily use the error-prone NHEJ to repair DSBs throughout the cell cycle, which leads to gene rearrangement, cell death, and increased sensitivity to anticancer therapies (9-11). Consistently, BRCA1-null mice are early embryonic lethal (12, 13) and codepletion of TP53BP1 rescued the lethality phenotype of BRCA1-null mice (12)(13)(14).Low expression level of 53BP1 was found to be associated with poor clinical outcome in triple negative breast cancer patients with BRCA1 mutation (12, 15), as well as resistance to genotoxins and poly(ADP-ribose) polymerase inhibitors (12,16,17). This finding is probably because loss of 53BP1 restored HR and promoted cell survival (12-14). Reduced expression of 53BP1 was also observed in tumors from the brain (18), lymph node (19), and pancreas (20). These data indicate that loss of 53BP1 might be a common mechanism for advanced tumors to evade from radiotherapy or chemotherapy. However, molecular mechanisms controlling the protein level of 53BP1 remain less well understood.Here we show that UbcH7, an E2 enzyme involved in the ubiquitin (Ub) pathway, controls the protein stability of 53BP1, thereby determining the DSB repair choice. Loss of UbcH7 sta...

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Section: Resultsmentioning

confidence: 99%

UbcH7 regulates 53BP1 stability and DSB repair

Han¹,

Zhang²,

Chung³

et al. 2014

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

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“…Accumulating evidence suggests a critical role of ubiquitination in mediating DNA damage responses (25,59). Upon DNA damage, MDC1 is recruited to DSBs by ␥H2AX through a direct interaction of its BRCT domains with ␥H2AX (16).…”

Section: Discussionmentioning

confidence: 99%

“…Upon DNA damage, ubiquitination occurs at DSB sites, and a number of proteins involved in the ubiquitination process are accumulated at DSBs and play critical roles in mediating DNA damage responses (24,25). For instance, BRCA1, a key player of HR-mediated DSB repair, contains an N-terminal RING domain that interacts with BARD1 to form a heterodimeric E3 ubiquitin ligase (26,27).…”

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confidence: 99%

The RING Finger Protein RNF8 Ubiquitinates Nbs1 to Promote DNA Double-strand Break Repair by Homologous Recombination

Truong

Aslanian

et al. 2012

Journal of Biological Chemistry

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Background:The Mre11-Rad50-Nbs1 (MRN) complex and the ubiquitin E3 ligase RNF8 play important roles in DNA DSB repair. Results: RNF8 interacts with and ubiquitinates Nbs1 to promote binding of Nbs1 to DSBs and HR-mediated DSB repair. Conclusion: Nbs1 ubiquitination by RNF8 is important for Nbs1 recruitment to DSBs and HR-mediated repair of DSBs. Significance: These studies help to understand how ubiquitination modifications contribute to DSB repair and genome stability maintenance in mammalian cells.

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“…[7][8][9] Ubiquitination of γH2AX and H2A is an important event in DDR. [10][11][12] Following ATM and/or ATR recruitment to DNA damage and H2AX phosphorylation, mediator MDC1 is recruited to double/single-strand DNA breaks (DSB/SSB) and serves as a platform for recruiting 2 RING-type ubiquitin (Ub) ligases, RNF8 and RNF168, to modify γH2AX and H2A. [13][14][15] Therefore, ubiquitination of γH2AX and H2A in DDR is a process dependent on ATM/ATR, H2AX phosphorylation, and mediator MDC1.…”

Section: Introductionmentioning

confidence: 99%