Photo-Induced DNA Double-Strand Breaks Monitored by Single-Molecule Observation: Protective Effect of Antioxidative Compounds

Non-homologous end joining (NHEJ) is a major repair pathway for DNA double-strand breaks (DSBs), which is the most toxic DNA damage in cells. Unrepaired DSBs can cause genome instability, tumorigenesis or cell death. DNA end synapsis is the first and probably the most important step of the NHEJ pathway, aiming to bring two broken DNA ends close together and provide structural stability for end processing and ligation. This process is mediated through a group of NHEJ proteins forming higher-order complexes, to recognise and bridge two DNA ends. Spatial and temporal understanding of the structural mechanism of DNA-end synapsis has been largely advanced through recent structural and single-molecule studies of NHEJ proteins. This review focuses on core NHEJ proteins that mediate DNA end synapsis through their unique structures and interaction properties, as well as how they play roles as anchor and linker proteins during the process of ‘bridge over troubled ends'.

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The protective effect of reduced glutathione on cadmium-induced DNA double-strand breaks

Human Health and Medical Engineering ◽

10.2495/hhme130521 ◽

2014 ◽

Author(s):

Xueyuan Li ◽

Weiwei Li ◽

Jinxin Kong ◽

Yongmei Qi ◽

Dejun Huang

Keyword(s):

Protective Effect ◽

Reduced Glutathione ◽

Double Strand Breaks ◽

Dna Double Strand Breaks ◽

Strand Breaks

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Single-molecule views on homologous recombination

Quarterly Reviews of Biophysics ◽

10.1017/s0033583513000073 ◽

2013 ◽

Vol 46 (4) ◽

pp. 323-348 ◽

Cited By ~ 15

Author(s):

Andrea Candelli ◽

Mauro Modesti ◽

Erwin J. G. Peterman ◽

Gijs J. L. Wuite

Keyword(s):

Homologous Recombination ◽

Single Molecule ◽

Genetic Instability ◽

Double Strand Breaks ◽

Dna Double Strand Breaks ◽

Single Stranded Dna ◽

Strand Breaks ◽

Future Developments ◽

Recent Developments ◽

Human Rad51

AbstractAll organisms need homologous recombination (HR) to repair DNA double-strand breaks. Defects in recombination are linked to genetic instability and to elevated risks in developing cancers. The central catalyst of HR is a nucleoprotein filament, consisting of recombinase proteins (human RAD51 or bacterial RecA) bound around single-stranded DNA. Over the last two decades, single-molecule techniques have provided substantial new insights into the dynamics of homologous recombination. Here, we survey important recent developments in this field of research and provide an outlook on future developments.

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Single-molecule imaging of transcription at damaged chromatin

Science Advances ◽

10.1126/sciadv.aau1249 ◽

2019 ◽

Vol 5 (1) ◽

pp. eaau1249 ◽

Cited By ~ 16

Author(s):

Alexandra C. Vítor ◽

Sreerama C. Sridhara ◽

João C. Sabino ◽

Ana I. Afonso ◽

Ana R. Grosso ◽

...

Keyword(s):

Dna Damage ◽

Single Molecule ◽

Transcription Initiation ◽

Double Strand Breaks ◽

Dna Double Strand Breaks ◽

Strand Breaks ◽

Reciprocal Interactions ◽

Genomic Location ◽

Internal Exon ◽

Reporter Systems

How DNA double-strand breaks (DSBs) affect ongoing transcription remains elusive due to the lack of single-molecule resolution tools directly measuring transcription dynamics upon DNA damage. Here, we established new reporter systems that allow the visualization of individual nascent RNAs with high temporal and spatial resolution upon the controlled induction of a single DSB at two distinct chromatin locations: a promoter-proximal (PROP) region downstream the transcription start site and a region within an internal exon (EX2). Induction of a DSB resulted in a rapid suppression of preexisting transcription initiation regardless of the genomic location. However, while transcription was irreversibly suppressed upon a PROP DSB, damage at the EX2 region drove the formation of promoter-like nucleosome-depleted regions and transcription recovery. Two-color labeling of transcripts at sequences flanking the EX2 lesion revealed bidirectional break-induced transcription initiation. Transcriptome analysis further showed pervasive bidirectional transcription at endogenous intragenic DSBs. Our data provide a novel framework for interpreting the reciprocal interactions between transcription and DNA damage at distinct chromatin regions.

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Protective Effect of Ginseng on Radiation-Induced DNA Double Strand Breaks and Repair in Murine Lymphocytes

Cancer Biotherapy & Radiopharmaceuticals ◽

10.1089/cbr.1996.11.267 ◽

1996 ◽

Vol 11 (4) ◽

pp. 267-272 ◽

Cited By ~ 23

Author(s):

Tae-Hwan Kim ◽

Yun-Sil Lee ◽

Chul-Koo Cho ◽

Sanghee Park ◽

Soo-Yong Choi ◽

...

Keyword(s):

Protective Effect ◽

Double Strand Breaks ◽

Dna Double Strand Breaks ◽

Strand Breaks ◽

Radiation Induced

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Protective effect of chitosan oligosaccharide lactate against DNA double-strand breaks induced by a model methacrylate dental adhesive

Medical Science Monitor ◽

10.12659/msm.881898 ◽

2011 ◽

Vol 17 (8) ◽

pp. BR201-BR208 ◽

Cited By ~ 2

Author(s):

Joanna Szczepanska ◽

Elzbieta Pawlowska ◽

Ewelina Synowiec ◽

Piotr Czarny ◽

Marek Rekas ◽

...

Keyword(s):

Protective Effect ◽

Double Strand Breaks ◽

Chitosan Oligosaccharide ◽

Dna Double Strand Breaks ◽

Strand Breaks ◽

Dental Adhesive

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Mechanistic Insights From Single-Molecule Studies of Repair of Double Strand Breaks

Frontiers in Cell and Developmental Biology ◽

10.3389/fcell.2021.745311 ◽

2021 ◽

Vol 9 ◽

Author(s):

Muwen Kong ◽

Eric C. Greene

Keyword(s):

Single Molecule ◽

Genome Stability ◽

Double Strand Breaks ◽

Complex Nature ◽

Dna Double Strand Breaks ◽

End Joining ◽

Ensemble Averaging ◽

Strand Breaks ◽

Single Molecule Studies ◽

Risk Of Cancer

DNA double strand breaks (DSBs) are among some of the most deleterious forms of DNA damage. Left unrepaired, they are detrimental to genome stability, leading to high risk of cancer. Two major mechanisms are responsible for the repair of DSBs, homologous recombination (HR) and nonhomologous end joining (NHEJ). The complex nature of both pathways, involving a myriad of protein factors functioning in a highly coordinated manner at distinct stages of repair, lend themselves to detailed mechanistic studies using the latest single-molecule techniques. In avoiding ensemble averaging effects inherent to traditional biochemical or genetic methods, single-molecule studies have painted an increasingly detailed picture for every step of the DSB repair processes.

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Repair pathway choice for double-strand breaks

Essays in Biochemistry ◽

10.1042/ebc20200007 ◽

2020 ◽

Vol 64 (5) ◽

pp. 765-777 ◽

Cited By ~ 2

Author(s):

Yixi Xu ◽

Dongyi Xu

Keyword(s):

Cell Cycle ◽

Double Strand Breaks ◽

Homologous Region ◽

Gene Repair ◽

Repair Pathway ◽

Dna Double Strand Breaks ◽

Environmental Radiation ◽

Strand Breaks ◽

Dna End Resection ◽

End Resection

Abstract Deoxyribonucleic acid (DNA) is at a constant risk of damage from endogenous substances, environmental radiation, and chemical stressors. DNA double-strand breaks (DSBs) pose a significant threat to genomic integrity and cell survival. There are two major pathways for DSB repair: nonhomologous end-joining (NHEJ) and homologous recombination (HR). The extent of DNA end resection, which determines the length of the 3′ single-stranded DNA (ssDNA) overhang, is the primary factor that determines whether repair is carried out via NHEJ or HR. NHEJ, which does not require a 3′ ssDNA tail, occurs throughout the cell cycle. 53BP1 and the cofactors PTIP or RIF1-shieldin protect the broken DNA end, inhibit long-range end resection and thus promote NHEJ. In contrast, HR mainly occurs during the S/G2 phase and requires DNA end processing to create a 3′ tail that can invade a homologous region, ensuring faithful gene repair. BRCA1 and the cofactors CtIP, EXO1, BLM/DNA2, and the MRE11–RAD50–NBS1 (MRN) complex promote DNA end resection and thus HR. DNA resection is influenced by the cell cycle, the chromatin environment, and the complexity of the DNA end break. Herein, we summarize the key factors involved in repair pathway selection for DSBs and discuss recent related publications.

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