Pre-Exposure to Ionizing Radiation Stimulates DNA Double Strand Break End Resection, Promoting the Use of Homologous Recombination Repair

AbstractDNA end resection in eukaryotes is a key step in DNA homologous recombination (HR) and HR-mediated DNA double-strand break (DSB) repair, in which DNA2, EXO1 and MRE11 endo- and exonucleases remove several kilobases from the 5′ terminus of the DNA with DSB, while the 3′ terminus remains intact. The end resection-generated 3′ single-stranded DNA (ssDNA) overhang is then coated by RAD51 for subsequent strand invasion. In the last two decades, great progress has been made in understanding the biochemical mechanisms of end resection, including the identification of various enzymes involved in this process. However, some important questions about this process remain to be resolved. In this review, we summarize the general process of end resection and discuss the implications of the most recent findings for understanding of the end resection machinery.

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Biphasic recruitment of TRF2 to DNA damage sites promotes non-sister chromatid homologous recombination repair

10.1101/305169 ◽

2018 ◽

Author(s):

Xiangduo Kong ◽

Gladys Mae Saquilabon Cruz ◽

Sally Loyal Trinh ◽

Xu-Dong Zhu ◽

Michael W. Berns ◽

...

Keyword(s):

Dna Damage ◽

Homologous Recombination ◽

Sister Chromatid ◽

Strand Break ◽

Homologous Recombination Repair ◽

Telomeric Dna ◽

Dna Double Strand Break ◽

Mre11 Complex ◽

Recombination Repair ◽

Step Mechanism

AbstractTRF2 binds to telomeric repeats and is critical for telomere integrity. Evidence suggests that it also localizes to non-telomeric DNA damage sites. However, this recruitment appears to be precarious and functionally controversial. We find that TRF2 recruitment to damage sites occurs by a two-step mechanism: the initial rapid recruitment (phase I) and stable and prolonged association with damage sites (phase II). Phase I is poly(ADP-ribose) polymerase (PARP)-dependent and requires the N-terminal basic domain. The phase II recruitment requires the C-terminal MYB/SANT domain and the iDDR region in the hinge domain, which is mediated by the MRE11 complex and is stimulated by hTERT. PARP-dependent recruitment of intrinsically disordered proteins contributes to transient displacement of TRF2 that separates two phases. TRF2 binds to the I-PpoI-induced DNA double-strand break sites, which is enhanced by the presence of complex damage and is dependent on PARP and the MRE11 complex. TRF2 depletion affects non-sister chromatid homologous recombination (HR) repair, but not HR between sister chromatids or non-homologous endjoining pathways. Our results demonstrate a unique recruitment mechanism and function of TRF2 at non-telomeric DNA damage sites.Summary StatementTRF2 is recruited to DNA double-strand break damage sites by a two-step mechanism and functions in non-sister chromatid homologous recombination repair

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Formation of Large Palindromic DNA by Homologous Recombination of Short Inverted Repeat Sequences in Saccharomyces cerevisiae

Genetics ◽

10.1093/genetics/161.3.1065 ◽

2002 ◽

Vol 161 (3) ◽

pp. 1065-1075

Author(s):

David K Butler ◽

David Gillespie ◽

Brandi Steele

Keyword(s):

Homologous Recombination ◽

Inverted Repeat ◽

Excision Repair ◽

Strand Break ◽

Double Strand Break ◽

Repeat Sequence ◽

Inverted Repeat Sequence ◽

Repeat Sequences ◽

Dna Double Strand Break ◽

Intermolecular Reaction

Abstract Large DNA palindromes form sporadically in many eukaryotic and prokaryotic genomes and are often associated with amplified genes. The presence of a short inverted repeat sequence near a DNA double-strand break has been implicated in the formation of large palindromes in a variety of organisms. Previously we have established that in Saccharomyces cerevisae a linear DNA palindrome is efficiently formed from a single-copy circular plasmid when a DNA double-strand break is introduced next to a short inverted repeat sequence. In this study we address whether the linear palindromes form by an intermolecular reaction (that is, a reaction between two identical fragments in a head-to-head arrangement) or by an unusual intramolecular reaction, as it apparently does in other examples of palindrome formation. Our evidence supports a model in which palindromes are primarily formed by an intermolecular reaction involving homologous recombination of short inverted repeat sequences. We have also extended our investigation into the requirement for DNA double-strand break repair genes in palindrome formation. We have found that a deletion of the RAD52 gene significantly reduces palindrome formation by intermolecular recombination and that deletions of two other genes in the RAD52-epistasis group (RAD51 and MRE11) have little or no effect on palindrome formation. In addition, palindrome formation is dramatically reduced by a deletion of the nucleotide excision repair gene RAD1.

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RAD6 Promotes Homologous Recombination Repair by Activating the Autophagy-Mediated Degradation of Heterochromatin Protein HP1

Molecular and Cellular Biology ◽

10.1128/mcb.01044-14 ◽

2014 ◽

Vol 35 (2) ◽

pp. 406-416 ◽

Cited By ~ 26

Author(s):

Su Chen ◽

Chen Wang ◽

Luxi Sun ◽

Da-Liang Wang ◽

Lu Chen ◽

...

Keyword(s):

Homologous Recombination ◽

Genome Stability ◽

Chromosomal Rearrangements ◽

Strand Break ◽

Open Chromatin ◽

Dsb Repair ◽

Heterochromatin Protein ◽

Dna Double Strand Break ◽

Recombination Repair ◽

Ubiquitin Conjugating Enzyme

Efficient DNA double-strand break (DSB) repair is critical for the maintenance of genome stability. Unrepaired or misrepaired DSBs cause chromosomal rearrangements that can result in severe consequences, such as tumorigenesis. RAD6 is an E2 ubiquitin-conjugating enzyme that plays a pivotal role in repairing UV-induced DNA damage. Here, we present evidence that RAD6 is also required for DNA DSB repair via homologous recombination (HR) by specifically regulating the degradation of heterochromatin protein 1α (HP1α). Our study indicates that RAD6 physically interacts with HP1α and ubiquitinates HP1α at residue K154, thereby promoting HP1α degradation through the autophagy pathway and eventually leading to an open chromatin structure that facilitates efficient HR DSB repair. Furthermore, bioinformatics studies have indicated that the expression of RAD6 and HP1α exhibits an inverse relationship and correlates with the survival rate of patients.

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The effect of Hus1 on ionizing radiation sensitivity is associated with homologous recombination repair but is independent of nonhomologous end-joining

Oncogene ◽

10.1038/sj.onc.1209212 ◽

2005 ◽

Vol 25 (13) ◽

pp. 1980-1983 ◽

Cited By ~ 20

Author(s):

X Wang ◽

B Hu ◽

R S Weiss ◽

Y Wang

Keyword(s):

Homologous Recombination ◽

Ionizing Radiation ◽

Radiation Sensitivity ◽

Nonhomologous End Joining ◽

Homologous Recombination Repair ◽

End Joining ◽

Recombination Repair

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scid mutation in mice confers hypersensitivity to ionizing radiation and a deficiency in DNA double-strand break repair.

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.88.4.1394 ◽

1991 ◽

Vol 88 (4) ◽

pp. 1394-1397 ◽

Cited By ~ 280

Author(s):

K. A. Biedermann ◽

J. R. Sun ◽

A. J. Giaccia ◽

L. M. Tosto ◽

J. M. Brown

Keyword(s):

Ionizing Radiation ◽

Strand Break ◽

Double Strand Break ◽

Double Strand Break Repair ◽

Dna Double Strand Break ◽

Break Repair

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Schizosaccharomyces pombe KAT5 contributes to resection and repair of a DNA double strand break

Genetics ◽

10.1093/genetics/iyab042 ◽

2021 ◽

Author(s):

Tingting Li ◽

Ruben C Petreaca ◽

Susan L Forsburg

Keyword(s):

Dna Damage ◽

Homologous Recombination ◽

Chromatin Remodeling ◽

Dna Damage Response ◽

Histone Acetyltransferase ◽

Strand Break ◽

Double Strand Break ◽

Dna Damage Checkpoint ◽

Dna Double Strand Break ◽

Damage Response

Abstract Chromatin remodeling is essential for effective repair of a DNA double strand break. KAT5 (S. pombe Mst1, human TIP60) is a MYST family histone acetyltransferase conserved from yeast to humans that coordinates various DNA damage response activities at a DNA double strand break (DSB), including histone remodeling and activation of the DNA damage checkpoint. In S. pombe, mutations in mst1+ causes sensitivity to DNA damaging drugs. Here we show that Mst1 is recruited to DSBs. Mutation of mst1+ disrupts recruitment of repair proteins and delays resection. These defects are partially rescued by deletion of pku70, which has been previously shown to antagonize repair by homologous recombination. These phenotypes of mst1 are similar to pht1-4KR, a non-acetylatable form of histone variant H2A.Z, which has been proposed to affect resection. Our data suggest that Mst1 functions to direct repair of DSBs towards homologous recombination pathways by modulating resection at the double strand break.

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