scholarly journals Aspergillus nidulans uvsBATR and scaANBS1 Genes Show Genetic Interactions during Recovery from Replication Stress and DNA Damage

2005 ◽  
Vol 4 (7) ◽  
pp. 1239-1252 ◽  
Author(s):  
Marcia Regina von Zeska Kress Fagundes ◽  
Camile P. Semighini ◽  
Iran Malavazi ◽  
Marcela Savoldi ◽  
Joel Fernandes de Lima ◽  
...  
Keyword(s):  
Dna Damage ◽  
Aspergillus Nidulans ◽  
Replication Stress ◽  
Genetic Interactions ◽  
Dna Double Strand Breaks ◽  
Focus Formation ◽  
Strand Breaks ◽  
Mre11 Complex ◽  
Cellular Dna ◽  
Atr Kinases

ABSTRACT The ATM/ATR kinases and the Mre11 (Mre11-Rad50-Nbs1) protein complex are central players in the cellular DNA damage response. Here we characterize possible interactions between Aspergillus nidulans uvsB ATR and the Mre11 complex (scaA NBS1). We demonstrate that there is an epistatic relationship between uvsB ATR, the homolog of the ATR/MEC1 gene, and scaA NBS1, the homolog of the NBS1/XRS2 gene, for both repair and checkpoint functions and that correct ScaANBS1 expression during recovery from replication stress depends on uvsB ATR. In addition, we also show that the formation of UvsC foci during recovery from replication stress is dependent on both uvsB ATR and scaA NBS1 function. Furthermore, ScaANBS1 is also dependent on uvsB ATR for nuclear focus formation upon the induction of DNA double-strand breaks by phleomycin. Our results highlight the extensive genetic interactions between UvsB and the Mre11 complex that are required for S-phase progression and recovery from DNA damage.

scholarly journals DNA-PKcs: A Multi-Faceted Player in DNA Damage Response

2020 ◽  
Vol 11 ◽  
Author(s):  
Xiaoqiao Yue ◽  
Chenjun Bai ◽  
Dafei Xie ◽  
Teng Ma ◽  
Ping-Kun Zhou
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Cell Cycle Checkpoints ◽  
Dna Double Strand Breaks ◽  
Phosphatidylinositol 3 Kinase ◽  
Strand Breaks ◽  
Damage Response ◽  
Functional Complex ◽  
Dependent Protein ◽  
Cellular Dna

DNA-dependent protein kinase catalytic subunit (DNA-PKcs) is a member of the phosphatidylinositol 3-kinase related kinase family, which can phosphorylate more than 700 substrates. As the core enzyme, DNA-PKcs forms the active DNA-PK holoenzyme with the Ku80/Ku70 heterodimer to play crucial roles in cellular DNA damage response (DDR). Once DNA double strand breaks (DSBs) occur in the cells, DNA-PKcs is promptly recruited into damage sites and activated. DNA-PKcs is auto-phosphorylated and phosphorylated by Ataxia-Telangiectasia Mutated at multiple sites, and phosphorylates other targets, participating in a series of DDR and repair processes, which determine the cells’ fates: DSBs NHEJ repair and pathway choice, replication stress response, cell cycle checkpoints, telomeres length maintenance, senescence, autophagy, etc. Due to the special and multi-faceted roles of DNA-PKcs in the cellular responses to DNA damage, it is important to precisely regulate the formation and dynamic of its functional complex and activities for guarding genomic stability. On the other hand, targeting DNA-PKcs has been considered as a promising strategy of exploring novel radiosensitizers and killing agents of cancer cells. Combining DNA-PKcs inhibitors with radiotherapy can effectively enhance the efficacy of radiotherapy, offering more possibilities for cancer therapy.

scholarly journals The ubiquitin landscape at DNA double-strand breaks

2009 ◽  
Vol 187 (3) ◽  
pp. 319-326 ◽  
Author(s):  
Troy E. Messick ◽  
Roger A. Greenberg
Keyword(s):  
Dna Damage ◽  
Cancer Susceptibility ◽  
Strand Break ◽  
Dna Double Strand Breaks ◽  
Dsb Repair ◽  
Checkpoint Signaling ◽  
Strand Breaks ◽  
Parallel Processes ◽  
Dna Double Strand Break ◽  
Cellular Dna

The intimate relationship between DNA double-strand break (DSB) repair and cancer susceptibility has sparked profound interest in how transactions on DNA and chromatin surrounding DNA damage influence genome integrity. Recent evidence implicates a substantial commitment of the cellular DNA damage response machinery to the synthesis, recognition, and hydrolysis of ubiquitin chains at DNA damage sites. In this review, we propose that, in order to accommodate parallel processes involved in DSB repair and checkpoint signaling, DSB-associated ubiquitin structures must be nonuniform, using different linkages for distinct functional outputs. We highlight recent advances in the study of nondegradative ubiquitin signaling at DSBs, and discuss how recognition of different ubiquitin structures may influence DNA damage responses.

scholarly journals Loss of p53 suppresses replication-stress-induced DNA breakage in G1/S checkpoint deficient cells

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Bente Benedict ◽  
Tanja van Harn ◽  
Marleen Dekker ◽  
Simone Hermsen ◽  
Asli Kucukosmanoglu ◽  
...  
Keyword(s):  
Dna Damage ◽  
Cancer Cells ◽  
Replication Stress ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
Origin Firing ◽  
Strand Breaks ◽  
Dna Breakage ◽  
Cycle Arrest

In cancer cells, loss of G1/S control is often accompanied by p53 pathway inactivation, the latter usually rationalized as a necessity for suppressing cell cycle arrest and apoptosis. However, we found an unanticipated effect of p53 loss in mouse and human G1-checkpoint-deficient cells: reduction of DNA damage. We show that abrogation of the G1/S-checkpoint allowed cells to enter S-phase under growth-restricting conditions at the expense of severe replication stress manifesting as decelerated DNA replication, reduced origin firing and accumulation of DNA double-strand breaks. In this system, loss of p53 allowed mitogen-independent proliferation, not by suppressing apoptosis, but rather by restoring origin firing and reducing DNA breakage. Loss of G1/S control also caused DNA damage and activation of p53 in an in vivo retinoblastoma model. Moreover, in a teratoma model, loss of p53 reduced DNA breakage. Thus, loss of p53 may promote growth of incipient cancer cells by reducing replication-stress-induced DNA damage.

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.

Identification of a Topoisomerase I Mutant, scsA1, as an Extragenic Suppressor of a Mutation in scaANBS1, the Apparent Homolog of Human Nibrin in Aspergillus nidulans

Genetics ◽  
2003 ◽  
Vol 164 (3) ◽  
pp. 935-945 ◽  
Author(s):  
Marcia R Z Kress Fagundes ◽  
Larissa Fernandes ◽  
Marcela Savoldi ◽  
Steven D Harris ◽  
Maria H S Goldman ◽  
...  
Keyword(s):  
Dna Damage ◽  
Aspergillus Nidulans ◽  
Topoisomerase I ◽  
Cell Cycle Checkpoint ◽  
Dna Double Strand Breaks ◽  
Dna Damaging Agents ◽  
Cycle Checkpoint ◽  
Increased Sensitivity ◽  
Cellular Dna ◽  
Extragenic Suppressors

Abstract The Mre11-Rad50-Nbs1 protein complex has emerged as a central player in the human cellular DNA damage response, and recent observations suggest that these proteins are at least partially responsible for the linking of DNA damage detection to DNA repair and cell cycle checkpoint functions. Mutations in scaANBS1, which encodes the apparent homolog of human nibrin in Aspergillus nidulans, inhibit growth in the presence of the antitopoisomerase I drug camptothecin. This article describes the selection and characterization of extragenic suppressors of the scaA1 mutation, with the aim of identifying other proteins that interfere with the pathway or complex in which the ScaA would normally be involved. Fifteen extragenic suppressors of the scaA1 mutation were isolated. The topoisomerase I gene can complement one of these suppressors. Synergistic interaction between the scaANBS1 and scsATOP1 genes in the presence of DNA-damaging agents was observed. Overexpression of topoisomerase I in the scaA1 mutant causes increased sensitivity to DNA-damaging agents. The scsATOP1 and the scaANBS1 gene products could functionally interact in pathways that either monitor or repair DNA double-strand breaks.

scholarly journals A DNA Damage-Regulated BRCT-Containing Protein, TopBP1, Is Required for Cell Survival

2002 ◽  
Vol 22 (2) ◽  
pp. 555-566 ◽  
Author(s):  
Kazuhiko Yamane ◽  
Xianglin Wu ◽  
Junjie Chen
Keyword(s):  
Dna Damage ◽  
Cell Survival ◽  
Ataxia Telangiectasia ◽  
Topoisomerase Ii ◽  
Sequence Similarity ◽  
Dna Double Strand Breaks ◽  
Focus Formation ◽  
Replication Checkpoint ◽  
Strand Breaks

ABSTRACT BRCA1 carboxyl-terminal (BRCT) motifs are present in a number of proteins involved in DNA repair and/or DNA damage-signaling pathways. Human DNA topoisomerase II binding protein 1 (TopBP1) contains eight BRCT motifs and shares sequence similarity with the fission yeast Rad4/Cut5 protein and the budding yeast DPB11 protein, both of which are required for DNA damage and/or replication checkpoint controls. We report here that TopBP1 is phosphorylated in response to DNA double-strand breaks and replication blocks. TopBP1 forms nuclear foci and localizes to the sites of DNA damage or the arrested replication forks. In response to DNA strand breaks, TopBP1 phosphorylation depends on the ataxia telangiectasia mutated protein (ATM) in vivo. However, ATM-dependent phosphorylation of TopBP1 does not appear to be required for focus formation following DNA damage. Instead, focus formation relies on one of the BRCT motifs, BRCT5, in TopBP1. Antisense Morpholino oligomers against TopBP1 greatly reduced TopBP1 expression in vivo. Similar to that of ataxia telangiectasia-related protein (ATR), Chk1, or Hus1, downregulation of TopBP1 leads to reduced cell survival, probably due to increased apoptosis. Taken together, the data presented here suggest that, like its putative counterparts in yeast species, TopBP1 may be involved in DNA damage and replication checkpoint controls.

scholarly journals P53 Binding Protein 1 (53bp1) Is an Early Participant in the Cellular Response to DNA Double-Strand Breaks

2000 ◽  
Vol 151 (7) ◽  
pp. 1381-1390 ◽  
Author(s):  
Linda B. Schultz ◽  
Nabil H. Chehab ◽  
Asra Malikzay ◽  
Thanos D. Halazonetis
Keyword(s):  
Dna Damage ◽  
Cellular Response ◽  
Binding Protein ◽  
Intracellular Localization ◽  
Double Strand Breaks ◽  
Nuclear Staining ◽  
Dna Double Strand Breaks ◽  
Focus Formation ◽  
Fast Kinetics ◽  
Strand Breaks

p53 binding protein 1 (53BP1), a protein proposed to function as a transcriptional coactivator of the p53 tumor suppressor, has BRCT domains with high homology to the Saccharomyces cerevisiae Rad9p DNA damage checkpoint protein. To examine whether 53BP1 has a role in the cellular response to DNA damage, we probed its intracellular localization by immunofluorescence. In untreated primary cells and U2OS osteosarcoma cells, 53BP1 exhibited diffuse nuclear staining; whereas, within 5–15 min after exposure to ionizing radiation (IR), 53BP1 localized at discreet nuclear foci. We propose that these foci represent sites of processing of DNA double-strand breaks (DSBs), because they were induced by IR and chemicals that cause DSBs, but not by ultraviolet light; their peak number approximated the number of DSBs induced by IR and decreased over time with kinetics that parallel the rate of DNA repair; and they colocalized with IR-induced Mre11/NBS and γ-H2AX foci, which have been previously shown to localize at sites of DSBs. Formation of 53BP1 foci after irradiation was not dependent on ataxia-telangiectasia mutated (ATM), Nijmegen breakage syndrome (NBS1), or wild-type p53. Thus, the fast kinetics of 53BP1 focus formation after irradiation and the lack of dependency on ATM and NBS1 suggest that 53BP1 functions early in the cellular response to DNA DSBs.

scholarly journals NBS1 is required for macrophage homeostasis and functional activity in mice

Blood ◽  
2015 ◽  
Vol 126 (22) ◽  
pp. 2502-2510 ◽  
Author(s):  
Selma Pereira-Lopes ◽  
Juan Tur ◽  
Juan A. Calatayud-Subias ◽  
Jorge Lloberas ◽  
Travis H. Stracker ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Inflammatory Responses ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
Strand Breaks ◽  
Hypomorphic Allele ◽  
Mre11 Complex ◽  
Key Points ◽  
Damage Response

Key Points Nbs1 is a component of the MRE11 complex, which is a sensor of DNA double-strand breaks and plays a crucial role in the DNA damage response. In mice with a hypomorphic allele of Nbs1, macrophages exhibit increased senescence and abnormal proliferation and inflammatory responses.

scholarly journals PARP1 exhibits enhanced association and catalytic efficiency with γH2A.X-nucleosome

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Deepti Sharma ◽  
Louis De Falco ◽  
Sivaraman Padavattan ◽  
Chang Rao ◽  
Susana Geifman-Shochat ◽  
...  
Keyword(s):  
Dna Damage ◽  
Mutational Analysis ◽  
Catalytic Efficiency ◽  
Double Strand Breaks ◽  
Genomic Integrity ◽  
Dna Double Strand Breaks ◽  
Strand Breaks ◽  
Nucleosome Core ◽  
Epigenetic Marker ◽  
Kinetics Of

AbstractThe poly(ADP-ribose) polymerase, PARP1, plays a key role in maintaining genomic integrity by detecting DNA damage and mediating repair. γH2A.X is the primary histone marker for DNA double-strand breaks and PARP1 localizes to H2A.X-enriched chromatin damage sites, but the basis for this association is not clear. We characterize the kinetics of PARP1 binding to a variety of nucleosomes harbouring DNA double-strand breaks, which reveal that PARP1 associates faster with (γ)H2A.X- versus H2A-nucleosomes, resulting in a higher affinity for the former, which is maximal for γH2A.X-nucleosome that is also the activator eliciting the greatest poly-ADP-ribosylation catalytic efficiency. The enhanced activities with γH2A.X-nucleosome coincide with increased accessibility of the DNA termini resulting from the H2A.X-Ser139 phosphorylation. Indeed, H2A- and (γ)H2A.X-nucleosomes have distinct stability characteristics, which are rationalized by mutational analysis and (γ)H2A.X-nucleosome core crystal structures. This suggests that the γH2A.X epigenetic marker directly facilitates DNA repair by stabilizing PARP1 association and promoting catalysis.

scholarly journals RepID-deficient cancer cells are sensitized to a drug targeting p97/VCP segregase

2021 ◽  
Author(s):  
Sang-Min Jang ◽  
Christophe E. Redon ◽  
Haiqing Fu ◽  
Fred E. Indig ◽  
Mirit I. Aladjem
Keyword(s):  
Dna Damage ◽  
Cancer Cells ◽  
Cell Sorting ◽  
Clonogenic Survival ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
Strand Breaks ◽  
Ubiquitinated Proteins ◽  
Damage Response ◽  
Survival Assay

Abstract Background The p97/valosin-containing protein (VCP) complex is a crucial factor for the segregation of ubiquitinated proteins in the DNA damage response and repair pathway. Objective We investigated whether blocking the p97/VCP function can inhibit the proliferation of RepID-deficient cancer cells using immunofluorescence, clonogenic survival assay, fluorescence-activated cell sorting, and immunoblotting. Result p97/VCP was recruited to chromatin and colocalized with DNA double-strand breaks in RepID-deficient cancer cells that undergo spontaneous DNA damage. Inhibition of p97/VCP induced death of RepID-depleted cancer cells. This study highlights the potential of targeting p97/VCP complex as an anticancer therapeutic approach. Conclusion Our results show that RepID is required to prevent excessive DNA damage at the endogenous levels. Localization of p97/VCP to DSB sites was induced based on spontaneous DNA damage in RepID-depleted cancer cells. Anticancer drugs targeting p97/VCP may be highly potent in RepID-deficient cells. Therefore, we suggest that p97/VCP inhibitors synergize with RepID depletion to kill cancer cells.

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