scholarly journals Microhomology-mediated End Joining and Homologous Recombination share the initial end resection step to repair DNA double-strand breaks in mammalian cells

2013 ◽  
Vol 110 (19) ◽  
pp. 7720-7725 ◽  
Author(s):  
L. N. Truong ◽  
Y. Li ◽  
L. Z. Shi ◽  
P. Y.-H. Hwang ◽  
J. He ◽  
...  
Keyword(s):  
Homologous Recombination ◽  
Mammalian Cells ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
End Joining ◽  
Strand Breaks ◽  
End Resection

scholarly journals Different Roles for Nonhomologous End Joining and Homologous Recombination following Replication Arrest in Mammalian Cells

2002 ◽  
Vol 22 (16) ◽  
pp. 5869-5878 ◽  
Author(s):  
Cecilia Lundin ◽  
Klaus Erixon ◽  
Catherine Arnaudeau ◽  
Niklas Schultz ◽  
Dag Jenssen ◽  
...  
Keyword(s):  
Homologous Recombination ◽  
Mammalian Cells ◽  
Double Strand Breaks ◽  
Nonhomologous End Joining ◽  
Replication Forks ◽  
Dna Double Strand Breaks ◽  
End Joining ◽  
Lethal Effects ◽  
Strand Breaks ◽  
Replication Arrest

ABSTRACT Homologous recombination (HR) and nonhomologous end joining (NHEJ) play overlapping roles in repair of DNA double-strand breaks (DSBs) generated during the S phase of the cell cycle. Here, we characterized the involvement of HR and NHEJ in the rescue of DNA replication forks arrested or slowed by treatment of hamster cells with hydroxyurea or thymidine. We show that the arrest of replication with hydroxyurea generates DNA fragmentation as a consequence of the formation of DSBs at newly replicated DNA. Both HR and NHEJ protected cells from the lethal effects of hydroxyurea, and this agent also increased the frequency of recombination mediated by both homologous and nonhomologous exchanges. Thymidine induced a less stringent arrest of replication and did not generate detectable DSBs. HR alone rescued cells from the lethal effects of thymidine. Furthermore, thymidine increased the frequency of DNA exchange mediated solely by HR in the absence of detectable DSBs. Our data suggest that both NHEJ and HR are involved in repair of arrested replication forks that include a DSB, while HR alone is required for the repair of slowed replication forks in the absence of detectable DSBs.

scholarly journals End-resection at DNA double-strand breaks in the three domains of life

2013 ◽  
Vol 41 (1) ◽  
pp. 314-320 ◽  
Author(s):  
John K. Blackwood ◽  
Neil J. Rzechorzek ◽  
Sian M. Bray ◽  
Joseph D. Maman ◽  
Luca Pellegrini ◽  
...  
Keyword(s):  
Dna Repair ◽  
Homologous Recombination ◽  
Strand Break ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
Strand Breaks ◽  
Homologous Chromosomes ◽  
Domains Of Life ◽  
Strand Invasion ◽  
End Resection

During DNA repair by HR (homologous recombination), the ends of a DNA DSB (double-strand break) must be resected to generate single-stranded tails, which are required for strand invasion and exchange with homologous chromosomes. This 5′–3′ end-resection of the DNA duplex is an essential process, conserved across all three domains of life: the bacteria, eukaryota and archaea. In the present review, we examine the numerous and redundant helicase and nuclease systems that function as the enzymatic analogues for this crucial process in the three major phylogenetic divisions.

scholarly journals Histone chaperone Anp32e removes H2A.Z from DNA double-strand breaks and promotes nucleosome reorganization and DNA repair

2015 ◽  
Vol 112 (24) ◽  
pp. 7507-7512 ◽  
Author(s):  
Ozge Gursoy-Yuzugullu ◽  
Marina K. Ayrapetov ◽  
Brendan D. Price
Keyword(s):  
Dna Damage ◽  
Double Strand Breaks ◽  
Histone H4 ◽  
Dna Double Strand Breaks ◽  
End Joining ◽  
Dsb Repair ◽  
Strand Breaks ◽  
Nucleosome Dynamics ◽  
Chromatin Template ◽  
End Resection

The repair of DNA double-strand breaks (DSBs) requires open, flexible chromatin domains. The NuA4–Tip60 complex creates these flexible chromatin structures by exchanging histone H2A.Z onto nucleosomes and promoting acetylation of histone H4. Here, we demonstrate that the accumulation of H2A.Z on nucleosomes at DSBs is transient, and that rapid eviction of H2A.Z is required for DSB repair. Anp32e, an H2A.Z chaperone that interacts with the C-terminal docking domain of H2A.Z, is rapidly recruited to DSBs. Anp32e functions to remove H2A.Z from nucleosomes, so that H2A.Z levels return to basal within 10 min of DNA damage. Further, H2A.Z removal by Anp32e disrupts inhibitory interactions between the histone H4 tail and the nucleosome surface, facilitating increased acetylation of histone H4 following DNA damage. When H2A.Z removal by Anp32e is blocked, nucleosomes at DSBs retain elevated levels of H2A.Z, and assume a more stable, hypoacetylated conformation. Further, loss of Anp32e leads to increased CtIP-dependent end resection, accumulation of single-stranded DNA, and an increase in repair by the alternative nonhomologous end joining pathway. Exchange of H2A.Z onto the chromatin and subsequent rapid removal by Anp32e are therefore critical for creating open, acetylated nucleosome structures and for controlling end resection by CtIP. Dynamic modulation of H2A.Z exchange and removal by Anp32e reveals the importance of the nucleosome surface and nucleosome dynamics in processing the damaged chromatin template during DSB repair.

scholarly journals CTCF cooperates with CtIP to drive homologous recombination repair of double-strand breaks

2019 ◽  
Vol 47 (17) ◽  
pp. 9160-9179 ◽  
Author(s):  
Soon Young Hwang ◽  
Mi Ae Kang ◽  
Chul Joon Baik ◽  
Yejin Lee ◽  
Ngo Thanh Hang ◽  
...  
Keyword(s):  
Homologous Recombination ◽  
Critical Role ◽  
Control Point ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
Strand Breaks ◽  
C Terminus ◽  
Dna End Resection ◽  
End Resection

Abstract The pleiotropic CCCTC-binding factor (CTCF) plays a role in homologous recombination (HR) repair of DNA double-strand breaks (DSBs). However, the precise mechanistic role of CTCF in HR remains largely unclear. Here, we show that CTCF engages in DNA end resection, which is the initial, crucial step in HR, through its interactions with MRE11 and CtIP. Depletion of CTCF profoundly impairs HR and attenuates CtIP recruitment at DSBs. CTCF physically interacts with MRE11 and CtIP and promotes CtIP recruitment to sites of DNA damage. Subsequently, CTCF facilitates DNA end resection to allow HR, in conjunction with MRE11–CtIP. Notably, the zinc finger domain of CTCF binds to both MRE11 and CtIP and enables proficient CtIP recruitment, DNA end resection and HR. The N-terminus of CTCF is able to bind to only MRE11 and its C-terminus is incapable of binding to MRE11 and CtIP, thereby resulting in compromised CtIP recruitment, DSB resection and HR. Overall, this suggests an important function of CTCF in DNA end resection through the recruitment of CtIP at DSBs. Collectively, our findings identify a critical role of CTCF at the first control point in selecting the HR repair pathway.

scholarly journals The internal region of CtIP negatively regulates DNA end resection

2020 ◽  
Vol 48 (10) ◽  
pp. 5485-5498 ◽  
Author(s):  
Sean Michael Howard ◽  
Ilaria Ceppi ◽  
Roopesh Anand ◽  
Roger Geiger ◽  
Petr Cejka
Keyword(s):  
Homologous Recombination ◽  
Regulatory Function ◽  
Dna Double Strand Breaks ◽  
End Joining ◽  
Strand Breaks ◽  
Internal Region ◽  
Dna End Resection ◽  
End Resection

Abstract DNA double-strand breaks are repaired by end-joining or homologous recombination. A key-committing step of recombination is DNA end resection. In resection, phosphorylated CtIP first promotes the endonuclease of MRE11–RAD50–NBS1 (MRN). Subsequently, CtIP also stimulates the WRN/BLM–DNA2 pathway, coordinating thus both short and long-range resection. The structure of CtIP differs from its orthologues in yeast, as it contains a large internal unstructured region. Here, we conducted a domain analysis of CtIP to define the function of the internal region in DNA end resection. We found that residues 350–600 were entirely dispensable for resection in vitro. A mutant lacking these residues was unexpectedly more efficient than full-length CtIP in DNA end resection and homologous recombination in vivo, and consequently conferred resistance to lesions induced by the topoisomerase poison camptothecin, which require high MRN–CtIP-dependent resection activity for repair. This suggested that the internal CtIP region, further mapped to residues 550–600, may mediate a negative regulatory function to prevent over resection in vivo. The CtIP internal deletion mutant exhibited sensitivity to other DNA-damaging drugs, showing that upregulated resection may be instead toxic under different conditions. These experiments together identify a region within the central CtIP domain that negatively regulates DNA end resection.

Double-strand-break-induced homologous recombination in mammalian cells

2001 ◽  
Vol 29 (2) ◽  
pp. 196-201 ◽  
Author(s):  
R. D. Johnson ◽  
M. Jasin
Keyword(s):  
Homologous Recombination ◽  
Sister Chromatid ◽  
Mammalian Cells ◽  
Indirect Evidence ◽  
Strand Break ◽  
Double Strand Breaks ◽  
Crossing Over ◽  
Dna Double Strand Breaks ◽  
Dsb Repair ◽  
Strand Breaks

In mammalian cells, the repair of DNA double-strand breaks (DSBs) occurs by both homologous and non-homologous mechanisms. Indirect evidence, including that from gene targeting and random integration experiments, had suggested that non-homologous mechanisms were significantly more frequent than homologous ones. However, more recent experiments indicate that homologous recombination is also a prominent DSB repair pathway. These experiments show that mammalian cells use homologous sequences located at multiple positions throughout the genome to repair a DSB. However, template preference appears to be biased, with the sister chromatid being preferred by 2–3 orders of magnitude over a homologous or heterologous chromosome. The outcome of homologous recombination in mammalian cells is predominantly gene conversion that is not associated with crossing-over. The preference for the sister chromatid and the bias against crossing-over seen in mitotic mammalian cells may have developed in order to reduce the potential for genome alterations that could occur when other homologous repair templates are utilized. In attempts to understand further the mechanism of homologous recombination, the proteins that promote this process are beginning to be identified. To date, four mammalian proteins have been demonstrated conclusively to be involved in DSB repair by homologous recombination: Rad54, XRCC2, XRCC3 and BRCAI. This paper summarizes results from a number of recent studies.

scholarly journals Homologous recombination preferentially repairs heat-induced DNA double-strand breaks in mammalian cells

2016 ◽  
Vol 33 (3) ◽  
pp. 336-342 ◽  
Author(s):  
Akihisa Takahashi ◽  
Eiichiro Mori ◽  
Yosuke Nakagawa ◽  
Atsuhisa Kajihara ◽  
Tadaaki Kirita ◽  
...  
Keyword(s):  
Homologous Recombination ◽  
Mammalian Cells ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
Strand Breaks

scholarly journals RAD51 Is Required for the Repair of Plasmid Double-Stranded DNA Gaps from Either Plasmid or Chromosomal Templates

2000 ◽  
Vol 20 (4) ◽  
pp. 1194-1205 ◽  
Author(s):  
Stephan Bärtsch ◽  
Leslie E. Kang ◽  
Lorraine S. Symington
Keyword(s):  
Homologous Recombination ◽  
Double Strand Breaks ◽  
Crossing Over ◽  
Dna Double Strand Breaks ◽  
End Joining ◽  
Radiation Chemical ◽  
Strand Breaks ◽  
Independent Events ◽  
In The Wild ◽  
A Minor

ABSTRACT DNA double-strand breaks may be induced by endonucleases, ionizing radiation, chemical agents, and mechanical forces or by replication of single-stranded nicked chromosomes. Repair of double-strand breaks can occur by homologous recombination or by nonhomologous end joining. A system was developed to measure the efficiency of plasmid gap repair by homologous recombination using either chromosomal or plasmid templates. Gap repair was biased toward gene conversion events unassociated with crossing over using either donor sequence. The dependence of recombinational gap repair on genes belonging to the RAD52epistasis group was tested in this system. RAD51,RAD52, RAD57, and RAD59 were required for efficient gap repair using either chromosomal or plasmid donors. No homologous recombination products were recovered fromrad52 mutants, whereas a low level of repair occurred in the absence of RAD51, RAD57, orRAD59. These results suggest a minor pathway of strand invasion that is dependent on RAD52 but not onRAD51. The residual repair events in rad51mutants were more frequently associated with crossing over than was observed in the wild-type strain, suggesting that the mechanisms forRAD51-dependent and RAD51-independent events are different. Plasmid gap repair was reduced synergistically inrad51 rad59 double mutants, indicating an important role for RAD59 in RAD51-independent repair.

Sign in / Sign up

Export Citation Format

Share Document