scholarly journals Kinase-dead ATM protein causes genomic instability and early embryonic lethality in mice

2012 ◽  
Vol 198 (3) ◽  
pp. 305-313 ◽  
Author(s):  
Kenta Yamamoto ◽  
Yunyue Wang ◽  
Wenxia Jiang ◽  
Xiangyu Liu ◽  
Richard L. Dubois ◽  
...  
Keyword(s):  
Dna Repair ◽  
Embryonic Development ◽  
Genomic Instability ◽  
Cell Cycle Checkpoint ◽  
End Joining ◽  
Atm Kinase ◽  
Class Switch ◽  
Early Embryonic Lethality ◽  
Cycle Checkpoint ◽  
Atm Protein

Ataxia telangiectasia (A-T) mutated (ATM) kinase orchestrates deoxyribonucleic acid (DNA) damage responses by phosphorylating numerous substrates implicated in DNA repair and cell cycle checkpoint activation. A-T patients and mouse models that express no ATM protein undergo normal embryonic development but exhibit pleiotropic DNA repair defects. In this paper, we report that mice carrying homozygous kinase-dead mutations in Atm (AtmKD/KD) died during early embryonic development. AtmKD/− cells exhibited proliferation defects and genomic instability, especially chromatid breaks, at levels higher than Atm−/− cells. Despite this increased genomic instability, AtmKD/− lymphocytes progressed through variable, diversity, and joining recombination and immunoglobulin class switch recombination, two events requiring nonhomologous end joining, at levels comparable to Atm−/− lymphocytes. Together, these results reveal an essential function of ATM during embryogenesis and an important function of catalytically inactive ATM protein in DNA repair.

scholarly journals Involvement of Human MOF in ATM Function

2005 ◽  
Vol 25 (12) ◽  
pp. 5292-5305 ◽  
Author(s):  
Arun Gupta ◽  
Girdhar G. Sharma ◽  
Charles S. H. Young ◽  
Manjula Agarwal ◽  
Edwin R. Smith ◽  
...  
Keyword(s):  
Dna Repair ◽  
Cell Cycle Checkpoint ◽  
Dominant Negative ◽  
Dominant Negative Mutant ◽  
Histone H4 ◽  
Dna Double Strand Breaks ◽  
Atm Kinase ◽  
Checkpoint Response ◽  
Downstream Effectors ◽  
Cycle Checkpoint

ABSTRACT We have determined that hMOF, the human ortholog of the Drosophila MOF gene (males absent on the first), encoding a protein with histone acetyltransferase activity, interacts with the ATM (ataxia-telangiectasia-mutated) protein. Cellular exposure to ionizing radiation (IR) enhances hMOF-dependent acetylation of its target substrate, lysine 16 (K16) of histone H4 independently of ATM function. Blocking the IR-induced increase in acetylation of histone H4 at K16, either by the expression of a dominant negative mutant ΔhMOF or by RNA interference-mediated hMOF knockdown, resulted in decreased ATM autophosphorylation, ATM kinase activity, and the phosphorylation of downstream effectors of ATM and DNA repair while increasing cell killing. In addition, decreased hMOF activity was associated with loss of the cell cycle checkpoint response to DNA double-strand breaks. The overexpression of wild-type hMOF yielded the opposite results, i.e., a modest increase in cell survival and enhanced DNA repair after IR exposure. These results suggest that hMOF influences the function of ATM.

scholarly journals 53BP1 is required for class switch recombination

2004 ◽  
Vol 165 (4) ◽  
pp. 459-464 ◽  
Author(s):  
Irene M. Ward ◽  
Bernardo Reina-San-Martin ◽  
Alexandru Olaru ◽  
Kay Minn ◽  
Koji Tamada ◽  
...  
Keyword(s):  
Class Switch Recombination ◽  
Cell Cycle Checkpoint ◽  
Double Strand Breaks ◽  
Nonhomologous End Joining ◽  
Checkpoint Control ◽  
Dna Double Strand Breaks ◽  
End Joining ◽  
Strand Breaks ◽  
Class Switch ◽  
Cycle Checkpoint

53BP1 participates early in the DNA damage response and is involved in cell cycle checkpoint control. Moreover, the phenotype of mice and cells deficient in 53BP1 suggests a defect in DNA repair (Ward et al., 2003b). Therefore, we asked whether or not 53BP1 would be required for the efficient repair of DNA double strand breaks. Our data indicate that homologous recombination by gene conversion does not depend on 53BP1. Moreover, 53BP1-deficient mice support normal V(D)J recombination, indicating that 53BP1 is not required for “classic” nonhomologous end joining. However, class switch recombination is severely impaired in the absence of 53BP1, suggesting that 53BP1 facilitates DNA end joining in a way that is not required or redundant for the efficient closing of RAG-induced strand breaks. These findings are similar to those observed in mice or cells deficient in the tumor suppressors ATM and H2AX, further suggesting that the functions of ATM, H2AX, and 53BP1 are closely linked.

scholarly journals Dysregulated G2 phase checkpoint recovery pathway reduces DNA repair efficiency and increases chromosomal instability in a wide range of tumours

Oncogenesis ◽  
2021 ◽  
Vol 10 (5) ◽  
Author(s):  
Madushan Fernando ◽  
Pascal H. G. Duijf ◽  
Martina Proctor ◽  
Alexander J. Stevenson ◽  
Anna Ehmann ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Repair ◽  
Genomic Instability ◽  
Chromosomal Instability ◽  
Cell Cycle Checkpoint ◽  
Phase Cell ◽  
Checkpoint Recovery ◽  
Repair Efficiency ◽  
Cycle Checkpoint ◽  
G2 Phase

AbstractDefective DNA repair is being demonstrated to be a useful target in cancer treatment. Currently, defective repair is identified by specific gene mutations, however defective repair is a common feature of cancers without these mutations. DNA damage triggers cell cycle checkpoints that are responsible for co-ordinating cell cycle arrest and DNA repair. Defects in checkpoint signalling components such as ataxia telangiectasia mutated (ATM) occur in a low proportion of cancers and are responsible for reduced DNA repair and increased genomic instability. Here we have investigated the AURKA-PLK1 cell cycle checkpoint recovery pathway that is responsible for exit from the G2 phase cell cycle checkpoint arrest. We demonstrate that dysregulation of PP6 and AURKA maintained elevated PLK1 activation to promote premature exit from only ATM, and not ATR-dependent checkpoint arrest. Surprisingly, depletion of the B55α subunit of PP2A that negatively regulates PLK1 was capable of overcoming ATM and ATR checkpoint arrests. Dysregulation of the checkpoint recovery pathway reduced S/G2 phase DNA repair efficiency and increased genomic instability. We found a strong correlation between dysregulation of the PP6-AURKA-PLK1-B55α checkpoint recovery pathway with signatures of defective homologous recombination and increased chromosomal instability in several cancer types. This work has identified an unrealised source of G2 phase DNA repair defects and chromosomal instability that are likely to be sensitive to treatments targeting defective repair.

scholarly journals DNA repair and cell cycle checkpoint defects in a mouse model of ‘BRCAness’ are partially rescued by 53BP1 deletion

Cell Cycle ◽  
2018 ◽  
Vol 17 (7) ◽  
pp. 881-891 ◽  
Author(s):  
Sarah M. Misenko ◽  
Dharm S. Patel ◽  
Joonyoung Her ◽  
Samuel F. Bunting
Keyword(s):  
Cell Cycle ◽  
Dna Repair ◽  
Mouse Model ◽  
Cell Cycle Checkpoint ◽  
Cycle Checkpoint

scholarly journals WIP1 Promotes Homologous Recombination and Modulates Sensitivity to PARP Inhibitors

Cells ◽  
2019 ◽  
Vol 8 (10) ◽  
pp. 1258 ◽  
Author(s):  
Kamila Burdova ◽  
Radka Storchova ◽  
Matous Palek ◽  
Libor Macurek
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Homologous Recombination ◽  
Cancer Cells ◽  
Genotoxic Stress ◽  
Parp Inhibitors ◽  
Cell Cycle Checkpoint ◽  
Dna Lesion ◽  
Cycle Checkpoint ◽  
G2 Cells

Genotoxic stress triggers a combined action of DNA repair and cell cycle checkpoint pathways. Protein phosphatase 2C delta (referred to as WIP1) is involved in timely inactivation of DNA damage response by suppressing function of p53 and other targets at chromatin. Here we show that WIP1 promotes DNA repair through homologous recombination. Loss or inhibition of WIP1 delayed disappearance of the ionizing radiation-induced 53BP1 foci in S/G2 cells and promoted cell death. We identify breast cancer associated protein 1 (BRCA1) as interactor and substrate of WIP1 and demonstrate that WIP1 activity is needed for correct dynamics of BRCA1 recruitment to chromatin flanking the DNA lesion. In addition, WIP1 dephosphorylates 53BP1 at Threonine 543 that was previously implicated in mediating interaction with RIF1. Finally, we report that inhibition of WIP1 allowed accumulation of DNA damage in S/G2 cells and increased sensitivity of cancer cells to a poly-(ADP-ribose) polymerase inhibitor olaparib. We propose that inhibition of WIP1 may increase sensitivity of BRCA1-proficient cancer cells to olaparib.

The Leukemic Fusion Gene NUP98-HOXD13 Suppresses Non-Homologous End Joining Factors and Impairs DNA Double Strand Break Repair

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 521-521
Author(s):  
David L. Caudell ◽  
Abdul Gafoor A. Puthiyaveetil
Keyword(s):  
Dna Repair ◽  
B Lymphocytes ◽  
Fusion Gene ◽  
Double Strand Breaks ◽  
End Joining ◽  
Strand Breaks ◽  
Class Switch ◽  
Induction Pattern ◽  
Dna Break ◽  
Non Homologous End Joining

Abstract Abstract 521 Chromosomal translocations are hallmark features of hematologic malignancies that often require collaborating mutations for malignant transformation. These secondary mutations can occur spontaneously, or rather, be induced by the primary translocation. Mutations can occur as a result of DNA damage and misrepair with DNA double strand breaks being one of the most serious types of cell damage. Double strand breaks are classically repaired by the non-homologous end joining (NHEJ) mechanism and impaired NHEJ has been shown to promote mutagenesis. Transgenic mice expressing the myeloid leukemic fusion gene NUP98-HOXD13 (NHD13) develop Myelodysplastic syndrome and progress to acute leukemia after acquiring secondary mutations. Our studies have shown that B lymphocyte development and class switch recombination are impaired in stimulated B lymphocytes from NHD13 mice. Based on this, we used in vitro class switch recombination (CSR) to delineate the DNA break induction and repair mechanisms in NHD13 B lymphocytes. Naïve B lymphocytes were harvested from wild type (WT) and NHD13 spleens and cultured in the presence of E.coli Lipopolysaccharide (LPS) and IL-4 to induce CSR. The DNA break induction pattern was determined using phosphorylated H2AX labeling combined with confocal microscopy and flow cytometry. Our results showed that NHD13 B lymphocytes had a comparable break induction pattern, but significantly reduced DNA repair. Analysis of the cell cycle pattern of stimulated B cells at 24 hour intervals showed cell cycle arrest at the G2/M phase at 72 hours following stimulation—a hallmark feature of impaired DNA break repair. We analyzed the expression of classical NHEJ and alternative end joining factors including Ku70, Ku80, DNA Protein Kinase catalytic subunit (DNAPKcs), Xrcc4, DNA ligase 4, Ligase 1, and Ligase 3. Our results showed reduced expression of DNAPKcs, Ligase 4 and Xrcc4 in NHD13 B lymphocytes at 72 hours following stimulation, suggesting that cells failed to initiate NHEJ-mediated DNA repair. Our results suggest that a myeloid leukemic gene can impair the DNA repair mechanism and may indirectly promote mutations necessary for malignant transformation. Disclosures: No relevant conflicts of interest to declare.

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