scholarly journals The BRCA2-Interacting Protein BCCIP Functions in RAD51 and BRCA2 Focus Formation and Homologous Recombinational Repair

2005 ◽  
Vol 25 (5) ◽  
pp. 1949-1957 ◽  
Author(s):  
Huimei Lu ◽  
Xu Guo ◽  
Xiangbing Meng ◽  
Jingmei Liu ◽  
Chris Allen ◽  
...  
Keyword(s):  
Dna Damage ◽  
Genome Stability ◽  
Recombinational Repair ◽  
Dna Double Strand Breaks ◽  
Focus Formation ◽  
Interacting Protein ◽  
Strand Breaks ◽  
Homologous Recombinational Repair ◽  
Radiation Induced ◽  
Nuclear Foci

ABSTRACT Homologous recombinational repair (HRR) of DNA damage is critical for maintaining genome stability and tumor suppression. RAD51 and BRCA2 colocalization in nuclear foci is a hallmark of HRR. BRCA2 has important roles in RAD51 focus formation and HRR of DNA double-strand breaks (DSBs). We previously reported that BCCIPα interacts with BRCA2. We show that a second isoform, BCCIPβ, also interacts with BRCA2 and that this interaction occurs in a region shared by BCCIPα and BCCIPβ. We further show that chromatin-bound BRCA2 colocalizes with BCCIP nuclear foci and that most radiation-induced RAD51 foci colocalize with BCCIP. Reducing BCCIPα by 90% or BCCIPβ by 50% by RNA interference markedly reduces RAD51 and BRCA2 foci and reduces HRR of DSBs by 20- to 100-fold. Similarly, reducing BRCA2 by 50% reduces RAD51 and BCCIP foci. These data indicate that BCCIP is critical for BRCA2- and RAD51-dependent responses to DNA damage and HRR.

scholarly journals Rad51 Accumulation at Sites of DNA Damage and in Postreplicative Chromatin

2000 ◽  
Vol 150 (2) ◽  
pp. 283-292 ◽  
Author(s):  
Satoshi Tashiro ◽  
Joachim Walter ◽  
Akira Shinohara ◽  
Nanao Kamada ◽  
Thomas Cremer
Keyword(s):  
Dna Damage ◽  
Nuclear Dna ◽  
Fibroblast Cell ◽  
S Phase ◽  
Recombinational Repair ◽  
Dna Double Strand Breaks ◽  
Double Labeling ◽  
Strand Breaks ◽  
Homologous Recombinational Repair ◽  
Ultraviolet C

Rad51, a eukaryotic RecA homologue, plays a central role in homologous recombinational repair of DNA double-strand breaks (DSBs) in yeast and is conserved from yeast to human. Rad51 shows punctuate nuclear localization in human cells, called Rad51 foci, typically during the S phase (Tashiro, S., N. Kotomura, A. Shinohara, K. Tanaka, K. Ueda, and N. Kamada. 1996. Oncogene. 12:2165–2170). However, the topological relationships that exist in human S phase nuclei between Rad51 foci and damaged chromatin have not been studied thus far. Here, we report on ultraviolet microirradiation experiments of small nuclear areas and on whole cell ultraviolet C (UVC) irradiation experiments performed with a human fibroblast cell line. Before UV irradiation, nuclear DNA was sensitized by the incorporation of halogenated thymidine analogues. These experiments demonstrate the redistribution of Rad51 to the selectively damaged, labeled chromatin. Rad51 recruitment takes place from Rad51 foci scattered throughout the nucleus of nonirradiated cells in S phase. We also demonstrate the preferential association of Rad51 foci with postreplicative chromatin in contrast to replicating chromatin using a double labeling procedure with halogenated thymidine analogues. This finding supports a role of Rad51 in recombinational repair processes of DNA damage present in postreplicative chromatin.

scholarly journals RAD51 localization and activation following DNA damage

2004 ◽  
Vol 359 (1441) ◽  
pp. 87-93 ◽  
Author(s):  
Madalena Tarsounas ◽  
Adelina A. Davies ◽  
Stephen C. West
Keyword(s):  
Dna Damage ◽  
Genome Stability ◽  
Critical Role ◽  
S Phase ◽  
Double Strand Breaks ◽  
Focus Formation ◽  
Rad51 Protein ◽  
Strand Breaks ◽  
Dna Damaging Agents ◽  
Binding Level

The efficient repair of double–strand breaks in DNA is critical for the maintenance of genome stability. In response to ionizing radiation and other DNA–damaging agents, the RAD51 protein, which is essential for homologous recombination, relocalizes within the nucleus to form distinct foci that can be visualized by microscopy and are thought to represent sites where repair reactions take place. The formation of RAD51 foci in response to DNA damage is dependent upon BRCA2 and a series of proteins known as the RAD51 paralogues (RAD51B, RAD51C, RAD51D, XRCC2 and XRCC3), indicating that the components present within foci assemble in a carefully orchestrated and ordered manner. By contrast, RAD51 foci that form spontaneously as cells undergo DNA replication at S phase occur without the need for BRCA2 or the RAD51 paralogues. It is known that BRCA2 interacts directly with RAD51 through a series of degenerative motifs known as the BRC repeats. These interactions modulate the ability of RAD51 to bind DNA. Taken together, these observations indicate that BRCA2 plays a critical role in controlling the actions of RAD51 at both the microscopic (focus formation) and molecular (DNA binding) level.

scholarly journals Regulation of homologous recombinational repair by lamin B1 in radiation‐induced DNA damage

2015 ◽  
Vol 29 (6) ◽  
pp. 2514-2525 ◽  
Author(s):  
Ning‐Ang Liu ◽  
Jiying Sun ◽  
Kazuteru Kono ◽  
Yasunori Horikoshi ◽  
Tsuyoshi Ikura ◽  
...  
Keyword(s):  
Dna Damage ◽  
Recombinational Repair ◽  
Lamin B1 ◽  
Homologous Recombinational Repair ◽  
Radiation Induced

scholarly journals H2A.X Phosphorylation in Oxidative Stress and Risk Assessment in Plasma Medicine

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Clarissa S. Schütz ◽  
Matthias B. Stope ◽  
Sander Bekeschus
Keyword(s):  
Oxidative Stress ◽  
Dna Damage ◽  
Dna Double Strand Breaks ◽  
Plasma Medicine ◽  
Mutagenic Potential ◽  
Strand Breaks ◽  
Radiation Induced ◽  
And Function ◽  
Physical Plasma ◽  
Suitable Marker

At serine139-phosphorylated gamma histone H2A.X (γH2A.X) has been established over the decades as sensitive evidence of radiation-induced DNA damage, especially DNA double-strand breaks (DSBs) in radiation biology. Therefore, γH2A.X has been considered a suitable marker for biomedical applications and a general indicator of direct DNA damage with other therapeutic agents, such as cold physical plasma. Medical plasma technology generates a partially ionized gas releasing a plethora of reactive oxygen and nitrogen species (ROS) simultaneously that have been used for therapeutic purposes such as wound healing and cancer treatment. The quantification of γH2A.X as a surrogate parameter of direct DNA damage has often been used to assess genotoxicity in plasma-treated cells, whereas no sustainable mutagenic potential of the medical plasma treatment could be identified despite H2A.X phosphorylation. However, phosphorylated H2A.X occurs during apoptosis, which is associated with exposure to cold plasma and ROS. This review summarizes the current understanding of γH2A.X induction and function in oxidative stress in general and plasma medicine in particular. Due to the progress towards understanding the mechanisms of H2A.X phosphorylation in the absence of DSB and ROS, observations of γH2A.X in medical fields should be carefully interpreted.

scholarly journals HP1β Chromo Shadow Domain facilitates H2A ubiquitination for BRCA1 recruitment at DNA double-strand breaks

2022 ◽  
Author(s):  
Tej Pandita ◽  
Vijay Kumari Charaka ◽  
Sharmistha Chakraborty ◽  
Chi-Lin Tsai ◽  
Xiaoyan Wang ◽  
...  
Keyword(s):  
Dna Damage ◽  
Genome Stability ◽  
Strand Break ◽  
Dna Double Strand Breaks ◽  
Dsb Repair ◽  
Strand Breaks ◽  
Damage Repair ◽  
Dna Double Strand Break ◽  
Assembly Factor ◽  
Chromo Shadow Domain

Efficient DNA double strand break (DSB) repair by homologous recombination (HR), as orchestrated by histone and non-histone proteins, is critical to genome stability, replication, transcription, and cancer avoidance. Here we report that Heterochromatin Protein1 beta (HP1β) acts as a key component of the HR DNA resection step by regulating BRCA1 enrichment at DNA damage sites, a function largely dependent on the HP1β chromo shadow domain (CSD). HP1β itself is enriched at DSBs within gene-rich regions through a CSD interaction with Chromatin Assembly Factor 1 (CAF1) and HP1β depletion impairs subsequent BRCA1 enrichment. An added interaction of the HP1β CSD with the Polycomb Repressor Complex 1 ubiquitinase component RING1A facilitates BRCA1 recruitment by increasing H2A lysine 118-119 ubiquitination, a marker for BRCA1 recruitment. Our findings reveal that HP1β interactions, mediated through its CSD with RING1A, promote H2A ubiquitination and facilitate BRCA1 recruitment at DNA damage sites, a critical step in DSB repair by the HR pathway. These collective results unveil how HP1β is recruited to DSBs in gene-rich regions and how HP1β subsequently promotes BRCA1 recruitment to further HR DNA damage repair by stimulating CtIP-dependent resection.

scholarly journals RecO impedes RecG-SSB binding to impair the strand annealing recombination pathway in E.coli

2019 ◽  
Author(s):  
Xuefeng Pan ◽  
Li Yang ◽  
Nan Jiang ◽  
Xifang Chen ◽  
Bo Li ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Dna Repair ◽  
Dna Replication ◽  
Replication Fork ◽  
Double Strand Breaks ◽  
Recombinational Repair ◽  
Dna Double Strand Breaks ◽  
Strand Breaks ◽  
Homologous Recombinational Repair ◽  
Differential Binding

AbstractFaithful duplication of genomic DNA relies not only on the fidelity of DNA replication itself, but also on fully functional DNA repair and homologous recombination machinery. We report a molecular mechanism responsible for deciding homologous recombinational repair pathways during replication dictated by binding of RecO and RecG to SSB in E.coli. Using a RecG-yfp fusion protein, we found that RecG-yfp foci appeared only in the ΔrecG, ΔrecO and ΔrecA, ΔrecO double mutants. Surprisingly, foci were not observed in wild-type ΔrecG, or double mutants where recG and either recF or, separately recR were deleted. In addition, formation of RecG-yfp foci in the ΔrecO::kanR required wildtype ssb, as ssb-113 could not substitute. This suggests that RecG and RecO binding to SSB is competitive. We also found that the UV resistance of recO alone mutant increased to certain extent by supplementing RecG. In an ssb-113 mutant, RecO and RecG worked following a different pattern. Both RecO and RecG were able to participate in repairing UV damages when grown at permissive temperature, while they could also be involved in making DNA double strand breaks when grown at nonpermissive temperature. So, our results suggested that differential binding of RecG and RecO to SSB in a DNA replication fork in Escherichia coli.may be involved in determining whether the SDSA or DSBR pathway of homologous recombinational repair is used.Author summarySingle strand DNA binding proteins (SSB) stabilize DNA holoenzyme and prevent single strand DNA from folding into non-B DNA structures in a DNA replication fork. It has also been revealed that SSB can also act as a platform for some proteins working in DNA repair and recombination to access DNA molecules when DNA replication fork needs to be reestablished. In Escherichia coli, several proteins working primarily in DNA repair and recombination were found to participate in DNA replication fork resumption by physically interacting with SSB, including RecO and RecG etc. However the hierarchy of these proteins interacting with SSB in Escherichia coli has not been well defined. In this study, we demonstrated a differential binding of RecO and RecG to SSB in DNA replication was used to establish a RecO-dependent pathway of replication fork repair by abolishing a RecG-dependent replication fork repair. We also show that, RecG and RecO could randomly participate in DNA replication repair in the absence of a functional SSB, which may be responsible for the generation of DNA double strand breaks in an ssb-113 mutant in Escherichia coli.

scholarly journals DDB1 Maintains Genome Integrity through Regulation of Cdt1

2006 ◽  
Vol 26 (21) ◽  
pp. 7977-7990 ◽  
Author(s):  
Courtney A. Lovejoy ◽  
Kimberli Lock ◽  
Ashwini Yenamandra ◽  
David Cortez
Keyword(s):  
Dna Damage ◽  
Genome Stability ◽  
Genome Instability ◽  
Excision Repair ◽  
Dna Lesions ◽  
Cell Cycle Checkpoints ◽  
Dna Double Strand Breaks ◽  
Genome Maintenance ◽  
Strand Breaks ◽  
Ubiquitin Ligase Complex

ABSTRACT DDB1, a component of a Cul4A ubiquitin ligase complex, promotes nucleotide excision repair (NER) and regulates DNA replication. We have investigated the role of human DDB1 in maintaining genome stability. DDB1-depleted cells accumulate DNA double-strand breaks in widely dispersed regions throughout the genome and have activated ATM and ATR cell cycle checkpoints. Depletion of Cul4A yields similar phenotypes, indicating that an E3 ligase function of DDB1 is important for genome maintenance. In contrast, depletion of DDB2, XPA, or XPC does not cause activation of DNA damage checkpoints, indicating that defects in NER are not involved. One substrate of DDB1-Cul4A that is crucial for preventing genome instability is Cdt1. DDB1-depleted cells exhibit increased levels of Cdt1 protein and rereplication, despite containing other Cdt1 regulatory mechanisms. The rereplication, accumulation of DNA damage, and activation of checkpoint responses in DDB1-depleted cells require entry into S phase and are partially, but not completely, suppressed by codepletion of Cdt1. Therefore, DDB1 prevents DNA lesions from accumulating in replicating human cells, in part by regulating Cdt1 degradation.

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