scholarly journals Fanconi Anemia Protein FANCD2 Promotes Immunoglobulin Gene Conversion and DNA Repair through a Mechanism Related to Homologous Recombination

2005 ◽  
Vol 25 (1) ◽  
pp. 34-43 ◽  
Author(s):  
Kazuhiko Yamamoto ◽  
Seiki Hirano ◽  
Masamichi Ishiai ◽  
Kenichi Morishima ◽  
Hiroyuki Kitao ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Homologous Recombination ◽  
Gene Conversion ◽  
Fanconi Anemia ◽  
Strand Break ◽  
Immunoglobulin Gene ◽  
Dna Double Strand Break ◽  
Mutant Cells ◽  
Light Chain Locus

ABSTRACT Recent studies show overlap between Fanconi anemia (FA) proteins and those involved in DNA repair mediated by homologous recombination (HR). However, the mechanism by which FA proteins affect HR is unclear. FA proteins (FancA/C/E/F/G/L) form a multiprotein complex, which is responsible for DNA damage-induced FancD2 monoubiquitination, a key event for cellular resistance to DNA damage. Here, we show that FANCD2-disrupted DT40 chicken B-cell line is defective in HR-mediated DNA double-strand break (DSB) repair, as well as gene conversion at the immunoglobulin light-chain locus, an event also mediated by HR. Gene conversions occurring in mutant cells were associated with decreased nontemplated mutations. In contrast to these defects, we also found increased spontaneous sister chromatid exchange (SCE) and intact Rad51 foci formation after DNA damage. Thus, we propose that FancD2 promotes a subpathway of HR that normally mediates gene conversion by a mechanism that avoids crossing over and hence SCEs.

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

Genetics ◽  
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.

scholarly journals The VEGF receptor neuropilin 2 promotes homologous recombination by stimulating YAP/TAZ-mediated Rad51 expression

2019 ◽  
Vol 116 (28) ◽  
pp. 14174-14180 ◽  
Author(s):  
Ameer L. Elaimy ◽  
John J. Amante ◽  
Lihua Julie Zhu ◽  
Mengdie Wang ◽  
Charlotte S. Walmsley ◽  
...  
Keyword(s):  
Dna Repair ◽  
Homologous Recombination ◽  
Strand Break ◽  
Vegf Receptor ◽  
Vegf Signaling ◽  
Dna Double Strand Break ◽  
Essential Enzyme ◽  
And Function ◽  
Platinum Chemotherapy ◽  
Endothelial Growth Factor

Vascular endothelial growth factor (VEGF) signaling in tumor cells mediated by neuropilins (NRPs) contributes to the aggressive nature of several cancers, including triple-negative breast cancer (TNBC), independently of its role in angiogenesis. Understanding the mechanisms by which VEGF–NRP signaling contributes to the phenotype of such cancers is a significant and timely problem. We report that VEGF–NRP2 promote homologous recombination (HR) in BRCA1 wild-type TNBC cells by contributing to the expression and function of Rad51, an essential enzyme in the HR pathway that mediates efficient DNA double-strand break repair. Mechanistically, we provide evidence that VEGF–NRP2 stimulates YAP/TAZ-dependent Rad51 expression and that Rad51 is a direct YAP/TAZ–TEAD transcriptional target. We also discovered that VEGF–NRP2–YAP/TAZ signaling contributes to the resistance of TNBC cells to cisplatin and that Rad51 rescues the defects in DNA repair upon inhibition of either VEGF–NRP2 or YAP/TAZ. These findings reveal roles for VEGF–NRP2 and YAP/TAZ in DNA repair, and they indicate a unified mechanism involving VEGF–NRP2, YAP/TAZ, and Rad51 that contributes to resistance to platinum chemotherapy.

scholarly journals RecF and RecR Play Critical Roles in the Homologous Recombination and Single-Strand Annealing Pathways of Mycobacteria

2015 ◽  
Vol 197 (19) ◽  
pp. 3121-3132 ◽  
Author(s):  
Richa Gupta ◽  
Stewart Shuman ◽  
Michael S. Glickman
Keyword(s):  
Dna Repair ◽  
Homologous Recombination ◽  
Strand Break ◽  
Single Strand ◽  
Central Position ◽  
End Joining ◽  
Dna Double Strand Break ◽  
Single Strand Annealing ◽  
Strand Annealing

ABSTRACTMycobacteria encode three DNA double-strand break repair pathways: (i) RecA-dependent homologous recombination (HR), (ii) Ku-dependent nonhomologous end joining (NHEJ), and (iii) RecBCD-dependent single-strand annealing (SSA). Mycobacterial HR has two presynaptic pathway options that rely on the helicase-nuclease AdnAB and the strand annealing protein RecO, respectively. Ablation ofadnABorrecOindividually causes partial impairment of HR, but loss ofadnABandrecOin combination abolishes HR. RecO, which can accelerate annealing of single-stranded DNAin vitro, also participates in the SSA pathway. The functions of RecF and RecR, which, in other model bacteria, function in concert with RecO as mediators of RecA loading, have not been examined in mycobacteria. Here, we present a genetic analysis ofrecFandrecRin mycobacterial recombination. We find that RecF, like RecO, participates in the AdnAB-independent arm of the HR pathway and in SSA. In contrast, RecR is required for all HR in mycobacteria and for SSA. The essentiality of RecR as an agent of HR is yet another distinctive feature of mycobacterial DNA repair.IMPORTANCEThis study clarifies the molecular requirements for homologous recombination in mycobacteria. Specifically, we demonstrate that RecF and RecR play important roles in both the RecA-dependent homologous recombination and RecA-independent single-strand annealing pathways. Coupled with our previous findings (R. Gupta, M. Ryzhikov, O. Koroleva, M. Unciuleac, S. Shuman, S. Korolev, and M. S. Glickman, Nucleic Acids Res 41:2284–2295, 2013,http://dx.doi.org/10.1093/nar/gks1298), these results revise our view of mycobacterial recombination and place the RecFOR system in a central position in homology-dependent DNA repair.

scholarly journals Akt/PKB suppresses DNA damage processing and checkpoint activation in late G2

2010 ◽  
Vol 190 (3) ◽  
pp. 297-305 ◽  
Author(s):  
Naihan Xu ◽  
Nadia Hegarat ◽  
Elizabeth J. Black ◽  
Mary T. Scott ◽  
Helfrid Hochegger ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Protein A ◽  
Strand Break ◽  
Checkpoint Activation ◽  
Interacting Protein ◽  
Dna Double Strand Break ◽  
Radiation Induced ◽  
G2 Cells ◽  
Tumor Types

Using chemical genetics to reversibly inhibit Cdk1, we find that cells arrested in late G2 are unable to delay mitotic entry after irradiation. Late G2 cells detect DNA damage lesions and form γ-H2AX foci but fail to activate Chk1. This reflects a lack of DNA double-strand break processing because late G2 cells fail to recruit RPA (replication protein A), ATR (ataxia telangiectasia and Rad3 related), Rad51, or CtIP (C-terminal interacting protein) to sites of radiation-induced damage, events essential for both checkpoint activation and initiation of DNA repair by homologous recombination. Remarkably, inhibition of Akt/PKB (protein kinase B) restores DNA damage processing and Chk1 activation after irradiation in late G2. These data demonstrate a previously unrecognized role for Akt in cell cycle regulation of DNA repair and checkpoint activation. Because Akt/PKB is frequently activated in many tumor types, these findings have important implications for the evolution and therapy of such cancers.

Perfecting DNA double-strand break repair on transcribed chromatin

2020 ◽  
Vol 64 (5) ◽  
pp. 705-719 ◽  
Author(s):  
Xin Yi Tan ◽  
Michael S.Y. Huen
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Chromosomal Aberrations ◽  
Chromatin Structure ◽  
Genome Stability ◽  
Transcriptional Control ◽  
Strand Break ◽  
Double Strand Break ◽  
Dna Double Strand Break ◽  
Molecular Bases

Abstract Timely repair of DNA double-strand break (DSB) entails coordination with the local higher order chromatin structure and its transaction activities, including transcription. Recent studies are uncovering how DSBs trigger transient suppression of nearby transcription to permit faithful DNA repair, failing of which leads to elevated chromosomal aberrations and cell hypersensitivity to DNA damage. Here, we summarize the molecular bases for transcriptional control during DSB metabolism, and discuss how the exquisite coordination between the two DNA-templated processes may underlie maintenance of genome stability and cell homeostasis.

Phosphorylation of FANCA on S1449 Is Important for Fanconi Anemia (FA) Pathway Function.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 186-186
Author(s):  
Natalie B. Collins ◽  
Andrei Tomashevski ◽  
Gary M. Kupfer
Keyword(s):  
Dna Damage ◽  
Homologous Recombination ◽  
Dna Damage Response ◽  
Fanconi Anemia ◽  
Phosphorylation Site ◽  
Site Directed Mutagenesis ◽  
Wild Type ◽  
Damage Response ◽  
And Function ◽  
Mutant Cells

Abstract Previous work in our lab and others has shown that the Fanconi anemia proteins, FANCG and FANCA, are phosphoproteins. FANCG is phosphorylated at mitosis, and these phosphorylations are required for proper exit from chromatin at mitosis. FANCG is also phosphorylated after DNA damage, with the phosphorylation site required for wild-type sensitivity to DNA damaging agents. FANCA is also phosphorylated after DNA damage and localized to chromatin, but the site and significance of this phosphorylation were previously unknown. Mass spectrometry of FANCA revealed one phosphopeptide with phosphorylation on serine 1449. Site-directed mutagenesis of this residue to alanine (S1449A) abolished a slower mobility form of FANCA seen after MMC treatment. Furthermore, the S1449A mutant failed to completely correct the MMC hypersensitivity of FA-A mutant cells. S1449A mutant cells displayed lower than wild-type levels of FANCD2 monoubiquitination following DNA damage, and an increased number of gross chromosomal aberrations were seen in metaphase spreads from S1449A mutant cells when compared to wild type cells. Using a GFP reporter substrate to measure homologous recombination, cells expressing the S1449A FANCA failed to completely correct the homologous recombination defect seen in FA cells. Taken together, cells expressing FANCA S1449A display a variety of FA-associated phenotypes, suggesting that the phosphorylation of S1449 is a functionally significant event. The DNA damage response in human cells is, in large part, coordinated by phosphorylation events initiated by apical kinases ATM and ATR. S1449 is found in a consensus ATM site, therefore studies are underway to determine if ATM or ATR is the kinase responsible for FANCA phosphorylation at S1449. Phosphorylation is a crucial process in transducing the DNA damage response, and phosphorylation of FA proteins appears critical to both localization and function of the proteins. Understanding how phosphorylation marks are placed on FANCA will give insight into the role of FANCA in the DNA damage response.

scholarly journals Role for RAD18 in Homologous Recombination in DT40 Cells

2006 ◽  
Vol 26 (21) ◽  
pp. 8032-8041 ◽  
Author(s):  
Dávid Szüts ◽  
Laura J. Simpson ◽  
Sarah Kabani ◽  
Mitsuyoshi Yamazoe ◽  
Julian E. Sale
Keyword(s):  
Dna Damage ◽  
Homologous Recombination ◽  
Gene Conversion ◽  
Early Stage ◽  
Current Evidence ◽  
Recombination Reaction ◽  
Immunoglobulin Gene ◽  
Postreplication Repair ◽  
Strand Breaks ◽  
Dt40 Cells

ABSTRACT RAD18 is an E3 ubiquitin ligase that catalyzes the monoubiquitination of PCNA, a modification central to DNA damage bypass and postreplication repair in both yeast and vertebrates. Although current evidence suggests that homologous recombination provides an essential backup in vertebrate rad18 mutants, we show that in chicken DT40 cells this is not the case and that RAD18 plays a role in the recombination reaction itself. Gene conversion tracts in the immunoglobulin locus of rad18 cells are shorter and are associated with an increased frequency of deletions and duplications. rad18 cells also exhibit reduced efficiency of gene conversion induced by targeted double-strand breaks in a reporter construct. Blocking an early stage of the recombination reaction by disruption of XRCC3 not only suppresses immunoglobulin gene conversion but also prevents the aberrant immunoglobulin gene rearrangements associated with RAD18 deficiency, reverses the elevated sister chromatid exchange of the rad18 mutant, and reduces its sensitivity to DNA damage. Together, these data suggest that homologous recombination is toxic in the absence of RAD18 and show that, in addition to its established role in postreplication repair, RAD18 is also required for the orderly completion of gene conversion.

scholarly journals RIF1 acts in DNA repair through phosphopeptide recognition of 53BP1

2021 ◽  
Author(s):  
Dheva Setiaputra ◽  
Cristina Escribano-Diaz ◽  
Julia K. Reinert ◽  
Pooja Sadana ◽  
Dali Zong ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Binding Sites ◽  
Binding Protein ◽  
Strand Break ◽  
Chromatin Binding ◽  
Alternative Mode ◽  
Downstream Effectors ◽  
Dna Double Strand Break ◽  
Radiation Induced

SummaryThe chromatin-binding protein 53BP1 promotes DNA repair by orchestrating the recruitment of downstream effectors including PTIP, RIF1 and shieldin to DNA double-strand break sites. While how PTIP recognizes 53BP1 is known, the molecular details of RIF1 recruitment to DNA damage sites remains undefined. Here, we report that RIF1 is a phosphopeptide-binding protein that directly interacts with three phosphorylated 53BP1 epitopes. The RIF1-binding sites on 53BP1 share an essential LxL motif followed by two closely apposed phosphorylated residues. Simultaneous mutation of these sites on 53BP1 abrogates RIF1 accumulation into ionizing radiation-induced foci, but surprisingly only fully compromises 53BP1-dependent DNA repair when an alternative mode of shieldin recruitment to DNA damage sites is also disabled. Intriguingly, this alternative mode of recruitment still depends on RIF1 but does not require its interaction with 53BP1. RIF1 therefore employs phosphopeptide recognition to promote DNA repair but also modifies shieldin action independently of 53BP1 binding.

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