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Wang Y, Czap MS, Kim H, Lu H, Liu J, Chang Y, Romanienko PJ, Montagna C, Shen Z. The Mammalian KU70 C-terminus SAP Domain Is Required to Repair Exogenous DNA Damage. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.30.601420. [PMID: 38979328 PMCID: PMC11230462 DOI: 10.1101/2024.06.30.601420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
The mammalian non-homologous end joining (NHEJ) is required for V(D)J recombination as well as coping with exogenously induced DNA double strand breaks (DSBs). Initiated by the binding of KU70/KU80 (KU) dimer to DNA ends and the subsequent recruitment of the DNA- dependent protein kinase catalytic subunit (DNA-PKcs), NHEJ plays a key role in DNA repair. While there has been significant structural understandings of how KU70 participates in NHEJ, the specific function of its highly conserved C-terminal SAP domain remains elusive. In this study, we developed a novel mouse model by deleting the SAP domain but preserving the KU70 nuclear localization and its dimerization ability with KU80. We found that the KU70 SAP deletion did not affect the V(D)J recombination or animal development but significantly impaired the animals and cells in repairing exogenously induced DSBs. We further showed an inability of KU70-ΔSAP cells to retain the DNA Ligase IV (LIG4) and other NHEJ co-factors on chromatin, and a spreading pattern of DSB marker γH2AX in KU70-ΔSAP cells after DNA damage. Our findings suggest that a specific inhibition of the SAP function may offer an opportunity to modulate cell sensitivity to therapeutic DSB-inducing agents without interfering with the developmental function of KU70. KeyPoints Generation of a novel transgenic mouse line lacking the C-terminal conserved KU70-SAP domainKU70-SAP defends against exogenous DSBs, but unessential for development and V(D)J recombinationKU70-SAP aids in recruiting and retaining NHEJ components, such as LIG4, to DSB sites.
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Fowler FC, Chen BR, Zolnerowich N, Wu W, Pavani R, Paiano J, Peart C, Chen Z, Nussenzweig A, Sleckman BP, Tyler JK. DNA-PK promotes DNA end resection at DNA double strand breaks in G 0 cells. eLife 2022; 11:74700. [PMID: 35575473 PMCID: PMC9122494 DOI: 10.7554/elife.74700] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 05/06/2022] [Indexed: 11/16/2022] Open
Abstract
DNA double-strand break (DSB) repair by homologous recombination is confined to the S and G2 phases of the cell cycle partly due to 53BP1 antagonizing DNA end resection in G1 phase and non-cycling quiescent (G0) cells where DSBs are predominately repaired by non-homologous end joining (NHEJ). Unexpectedly, we uncovered extensive MRE11- and CtIP-dependent DNA end resection at DSBs in G0 murine and human cells. A whole genome CRISPR/Cas9 screen revealed the DNA-dependent kinase (DNA-PK) complex as a key factor in promoting DNA end resection in G0 cells. In agreement, depletion of FBXL12, which promotes ubiquitylation and removal of the KU70/KU80 subunits of DNA-PK from DSBs, promotes even more extensive resection in G0 cells. In contrast, a requirement for DNA-PK in promoting DNA end resection in proliferating cells at the G1 or G2 phase of the cell cycle was not observed. Our findings establish that DNA-PK uniquely promotes DNA end resection in G0, but not in G1 or G2 phase cells, which has important implications for DNA DSB repair in quiescent cells.
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Affiliation(s)
- Faith C Fowler
- Weill Cornell Medicine Pharmacology Graduate Program, New York, United States.,Weill Cornell Medicine, Department of Pathology and Laboratory Medicine, New York, United States
| | - Bo-Ruei Chen
- Department of Medicine, Division of Hematology and Oncology, O'Neal Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, United States
| | - Nicholas Zolnerowich
- Laboratory of Genome Integrity, National Cancer Institute, Bethesda, United States
| | - Wei Wu
- Laboratory of Genome Integrity, National Cancer Institute, Bethesda, United States
| | - Raphael Pavani
- Laboratory of Genome Integrity, National Cancer Institute, Bethesda, United States
| | - Jacob Paiano
- Laboratory of Genome Integrity, National Cancer Institute, Bethesda, United States
| | - Chelsea Peart
- Weill Cornell Medicine, Department of Pathology and Laboratory Medicine, New York, United States
| | - Zulong Chen
- Weill Cornell Medicine, Department of Pathology and Laboratory Medicine, New York, United States
| | - André Nussenzweig
- Laboratory of Genome Integrity, National Cancer Institute, Bethesda, United States
| | - Barry P Sleckman
- Department of Medicine, Division of Hematology and Oncology, O'Neal Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, United States
| | - Jessica K Tyler
- Weill Cornell Medicine, Department of Pathology and Laboratory Medicine, New York, United States
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Libri A, Marton T, Deriano L. The (Lack of) DNA Double-Strand Break Repair Pathway Choice During V(D)J Recombination. Front Genet 2022; 12:823943. [PMID: 35082840 PMCID: PMC8785701 DOI: 10.3389/fgene.2021.823943] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Accepted: 12/13/2021] [Indexed: 01/08/2023] Open
Abstract
DNA double-strand breaks (DSBs) are highly toxic lesions that can be mended via several DNA repair pathways. Multiple factors can influence the choice and the restrictiveness of repair towards a given pathway in order to warrant the maintenance of genome integrity. During V(D)J recombination, RAG-induced DSBs are (almost) exclusively repaired by the non-homologous end-joining (NHEJ) pathway for the benefit of antigen receptor gene diversity. Here, we review the various parameters that constrain repair of RAG-generated DSBs to NHEJ, including the peculiarity of DNA DSB ends generated by the RAG nuclease, the establishment and maintenance of a post-cleavage synaptic complex, and the protection of DNA ends against resection and (micro)homology-directed repair. In this physiological context, we highlight that certain DSBs have limited DNA repair pathway choice options.
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Affiliation(s)
- Alice Libri
- Genome Integrity, Immunity and Cancer Unit, Institut Pasteur, Université de Paris, INSERM U1223, Equipe Labellisée Ligue Contre Le Cancer, Paris, France
| | - Timea Marton
- Genome Integrity, Immunity and Cancer Unit, Institut Pasteur, Université de Paris, INSERM U1223, Equipe Labellisée Ligue Contre Le Cancer, Paris, France
| | - Ludovic Deriano
- Genome Integrity, Immunity and Cancer Unit, Institut Pasteur, Université de Paris, INSERM U1223, Equipe Labellisée Ligue Contre Le Cancer, Paris, France
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