scholarly journals Ensuring the Stability of the Genome: DNA Damage Checkpoints

2001 ◽  
Vol 1 ◽  
pp. 684-702 ◽  
Author(s):  
Christine Latif ◽  
Susan H. Harvey ◽  
Susan J. O'Connell
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Mammalian Cells ◽  
Cellular Response ◽  
Model Systems ◽  
Checkpoint Proteins ◽  
Functional Conservation ◽  
Cycle Arrest ◽  
A Cell ◽  
The Stability

The cellular response to DNA damage is vital for the cell�s ability to maintain genomic integrity. Checkpoint signalling pathways, which induce a cell cycle arrest in response to DNA damage, are an essential component of this process. This is reflected by the functional conservation of these pathways in all eukaryotes from yeast to mammalian cells. This review will examine the cellular response to DNA damage throughout the cell cycle. A key component of the DNA damage response is checkpoint signalling, which monitors the state of the genome prior to DNA replication (G1/S) and chromosome segregation (G2/M). Checkpoint signalling in model systems including mice, Xenopus laevis, Drosophila melanogaster, and the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe have been useful in elucidating these pathways in mammalian cells. An examination of this research, with emphasis on the function of checkpoint proteins, their relationship to DNA repair, and their involvement in oncogenesis is undertaken here.

scholarly journals Mitochondrial DNA Damage Initiates a Cell Cycle Arrest by a Chk2-associated Mechanism in Mammalian Cells

2009 ◽  
Vol 284 (52) ◽  
pp. 36191-36201 ◽  
Author(s):  
Christopher A. Koczor ◽  
Inna N. Shokolenko ◽  
Amy K. Boyd ◽  
Shawn P. Balk ◽  
Glenn L. Wilson ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Mitochondrial Dna ◽  
Cell Cycle Arrest ◽  
Mammalian Cells ◽  
Mitochondrial Dna Damage ◽  
Cycle Arrest ◽  
A Cell

scholarly journals The Histone Code of Senescence

Cells ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 466 ◽  
Author(s):  
Harikrishnareddy Paluvai ◽  
Eros Di Giorgio ◽  
Claudio Brancolini
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Cell Cycle Arrest ◽  
Cellular Response ◽  
Premature Aging ◽  
Physiological Processes ◽  
Cycle Arrest ◽  
Damage Response ◽  
Permanent Cell ◽  
Second Wave

Senescence is the end point of a complex cellular response that proceeds through a set of highly regulated steps. Initially, the permanent cell-cycle arrest that characterizes senescence is a pro-survival response to irreparable DNA damage. The maintenance of this prolonged condition requires the adaptation of the cells to an unfavorable, demanding and stressful microenvironment. This adaptation is orchestrated through a deep epigenetic resetting. A first wave of epigenetic changes builds a dam on irreparable DNA damage and sustains the pro-survival response and the cell-cycle arrest. Later on, a second wave of epigenetic modifications allows the genomic reorganization to sustain the transcription of pro-inflammatory genes. The balanced epigenetic dynamism of senescent cells influences physiological processes, such as differentiation, embryogenesis and aging, while its alteration leads to cancer, neurodegeneration and premature aging. Here we provide an overview of the most relevant histone modifications, which characterize senescence, aging and the activation of a prolonged DNA damage response.

scholarly journals The role of FOXO3 in DNA damage response in thyrocytes

2011 ◽  
Vol 18 (5) ◽  
pp. 555-564 ◽  
Author(s):  
Antje Klagge ◽  
Carl Weidinger ◽  
Kerstin Krause ◽  
Beate Jessnitzer ◽  
Monika Gutknecht ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Cell Cycle Arrest ◽  
Cellular Response ◽  
Wild Type ◽  
Cycle Arrest ◽  
Damage Repair ◽  
Cell Clones ◽  
Human Wild Type

Members of the forkhead box-O (FOXO) transcription factors family play an important role in stress defence. FOXO3 deregulation has recently been identified as a hallmark of thyroid carcinogenesis. In this study, we explore the role of FOXO3 in defence of oxidative stress in normal thyrocytes. Stable rat thyroid cell lines were generated expressing either the human wild-type FOXO3, a constitutively activating FOXO3 mutant, or the empty control vector. Cell clones were characterised for proliferation, function and morphology. Hydrogen peroxide and UV irradiation were used to induce oxidative stress. Changes in FOXO3 activity, induction of cell cycle arrest or apoptosis and kinetics of DNA damage repair were analysed. Upregulation of FOXO3 in thyrocytes resulted in decreased proliferation and changes in morphology, but did not affect differentiation. Hydrogen peroxide stimulated the expression of the FOXO3 target genes growth arrest and DNA damage-inducible protein 45 α (Gadd45α) and Bcl-2 interacting mediator of cell death (BIM) and induced programmed cell death in cells with overexpression of the human wild-type FOXO3. In contrast, UV irradiation resulted in a distinct cellular response with activation of FOXO3-c-Jun-N-terminal kinase-Gadd45α signalling and induction of cell cycle arrest at the G2-M-checkpoint. This was accompanied by FOXO3-induced DNA damage repair as evidenced by lower DNA breaks over time in a comet assay in FOXO3 cell clones compared with control cells. In conclusion, FOXO3 is a pivotal relay in the coordination of the cellular response to genotoxic stress in the thyroid. Depending on the stimulus, FOXO3 induces either cell cycle arrest or apoptosis. Conversely, FOXO3 inactivation in thyroid cancers is consistent with genomic instability and loss of cell cycle control.

Imaging with FLT-PET demonstrates that PF-477736, an inhibitor of CHK1 kinase, overcomes a cell cycle checkpoint induced by gemcitabine in PC-3 xenografts

2006 ◽  
Vol 24 (18_suppl) ◽  
pp. 3045-3045 ◽  
Author(s):  
G. A. McArthur ◽  
J. Raleigh ◽  
A. Blasina ◽  
C. Cullinane ◽  
D. Dorow ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Fold Increase ◽  
Cell Cycle Checkpoint ◽  
Flt Pet ◽  
Cycle Arrest ◽  
Cycle Checkpoint ◽  
A Cell ◽  
Chk1 Inhibitor

3045 Background: The development of strategies to monitor the molecular and cellular response to novel agents that target the cell cycle is vital to provide proof of mechanism and biological activity of these compounds. The protein kinase CHK1 is activated following DNA damage in the S and G2-phases of the cell cycle and mediates cell cycle arrest. In vitro studies demonstrate that inhibition of CHK1 can overcome cell cycle arrest induced by DNA damage and enhance cytotoxic activity of DNA damaging agents. In vivo studies show that combining DNA damaging agents with a CHK1 inhibitor potentiates antitumor activity. We hypothesize that functional imaging with 18F-fluorine-L-thymidine (FLT), a PET-tracer where tumor uptake is maximal in the S and G2 phases of the cell cycle can be used to non-invasively monitor the induction and therapeutic inhibition of a cell cycle checkpoint in vivo. Methods: Nude mice harbouring PC-3 xenografts were treated with vehicle controls, gemcitabine, the CHK1-inhibitor PF-477736 or gemcitabine + PF-477736. FLT-PET scans were performed and tumors harvested for ex-vivo biomarkers to assess S-phase, M-phase and DNA-repair. Results: Gemcitabine induced a 8.3 ±0.8 fold increase in tumoral uptake of FLT at 21 hours that correlated with a 3.3 ±0.2-fold increase in thymidine kinase activity and S-phase arrest as demonstrated by BrdU incorporation and elevated expression of cyclin-A. Treatment with PF-477736 at 17 hours after gemcitabine abrogated the early FLT-flare at 21 hours by 82% (p<0.001). This was associated with both an increased fraction of cells in mitosis and G1-phase of the cell cycle as determined by phos-histone H3 and flow cytometry. Furthermore, the combination of gemcitabine and PF-477736 enhanced DNA damage as measured by phos-gamma-H2AX and significantly delayed tumor growth when compared to tumors treated with gemcitabine alone. Conclusion: These data clearly indicate that the CHK1-inhibitor PF-477736 can overcome the cell cycle checkpoint induced by gemcitabine and increase associated DNA damage in tumors in-vivo. The PET studies indicate that functional imaging with FLT-PET is a promising strategy to monitor responses to therapeutic agents that target cell cycle checkpoints. [Table: see text]

scholarly journals H2AX Is Required for Cell Cycle Arrest via the p53/p21 Pathway

2009 ◽  
Vol 29 (10) ◽  
pp. 2828-2840 ◽  
Author(s):  
Michalis Fragkos ◽  
Jaana Jurvansuu ◽  
Peter Beard
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Cell Cycle Arrest ◽  
Cellular Response ◽  
Replication Fork ◽  
Mitotic Catastrophe ◽  
Adeno Associated Virus ◽  
Cycle Arrest ◽  
And Diffusion

ABSTRACT Phosphorylation of H2AX (γH2AX) is an early sign of DNA damage induced by replication stalling. However, the role of H2AX in the repair of this type of DNA damage is still unclear. In this study, we used an inactivated adeno-associated virus (AAV) to induce a stalled replication fork signal and investigate the function of γH2AX. The cellular response to AAV provides a unique model to study γH2AX function, because the infection causes pannuclear H2AX phosphorylation without any signs of damage to the host genome. We found that pannuclear γH2AX formation is a result of ATR overactivation and diffusion but is independent of ATM. The inhibition of H2AX with RNA interference or the use of H2AX-deficient cells showed that γH2AX is dispensable for the formation and maintenance of DNA repair foci induced by stalled replication. However, in the absence of H2AX, the AAV-containing cells showed proteosome-dependent degradation of p21, followed by caspase-dependent mitotic catastrophe. In contrast, H2AX-proficient cells as well as H2AX-complemented H2AX−/− cells reacted by increasing p21 levels and arresting the cell cycle. The results establish a new role for H2AX in the p53/p21 pathway and indicate that H2AX is required for p21-induced cell cycle arrest after replication stalling.

scholarly journals DNA Damage Caused by Ionizing Radiation in Embryonic Diploid Fibroblasts WI-38 Induces Both Apoptosis and Senescence

2011 ◽  
pp. 667-677 ◽  
Author(s):  
J. CMIELOVÁ ◽  
R. HAVELEK ◽  
A. JIROUTOVÁ ◽  
R. KOHLEROVÁ ◽  
M. SEIFRTOVÁ ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Ionizing Radiation ◽  
Cellular Response ◽  
Diploid Fibroblasts ◽  
Cycle Arrest ◽  
Permanent Cell ◽  
Radiation Induced ◽  
G2 Phase ◽  
Stress Induced Premature Senescence

Cellular response to ionizing radiation-induced damage depends on the cell type and the ability to repair DNA damage. Some types of cells undergo apoptosis, whereas others induce a permanent cell cycle arrest and do not proliferate. Our study demonstrates two types of response of embryonic diploid fibroblasts WI-38 to ionizing radiation. In the WI-38 cells p53 is activated, protein p21 increases, but the cells are arrested in G2 phase of cell cycle. Some of the cells die by apoptosis, but in remaining viable cells p16 increases, senescence associated DNA-damage foci occur, and senescence-associated beta-galactosidase activity increases, which indicate stress-induced premature senescence.

scholarly journals An ATM/Wip1-dependent timer controls the minimal duration of a DNA-damage mediated cell cycle arrest

2016 ◽  
Author(s):  
Himjyot Jaiswal ◽  
Jan Benada ◽  
Erik Mullers ◽  
Karen Akopyan ◽  
Kamila Burdova ◽  
...  
Keyword(s):  
Experimental Data ◽  
Cell Cycle ◽  
Dna Damage ◽  
Cell Cycle Arrest ◽  
Dna Lesions ◽  
Cycle Arrest ◽  
Checkpoint Adaptation ◽  
Global Spread ◽  
A Cell ◽  
G2 Phase

After DNA damage, the cell cycle is arrested to avoid propagation of mutations. In G2 phase, the arrest is initiated by ATM/ATR-dependent signalling that blocks mitosis-promoting kinases as Plk1. Interestingly, Plk1 can counteract ATR-dependent signalling and is required for eventual resumption of the cell cycle. However, what determines when Plk1 activity can resume remains unclear. Here we use FRET-based reporters to show that a global spread of ATM activity on chromatin and phosphorylation of targets including Kap1 control Plk1 re-activation. These phosphorylations are rapidly counteracted by the chromatin-bound phosphatase Wip1, allowing a cell cycle restart despite persistent ATM activity present at DNA lesions. Combining experimental data and mathematical modelling we propose that the minimal duration of a cell cycle arrest is controlled by a timer. Our model shows how cell cycle re-start can occur before completion of DNA repair and suggests a mechanism for checkpoint adaptation in human cells.

scholarly journals Modelling the checkpoint response to telomere uncapping in budding yeast

2006 ◽  
Vol 4 (12) ◽  
pp. 73-90 ◽  
Author(s):  
C.J Proctor ◽  
D.A Lydall ◽  
R.J Boys ◽  
C.S Gillespie ◽  
D.P Shanley ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Dna Repair ◽  
Cell Cycle Arrest ◽  
Dna Damage Response ◽  
Time Course ◽  
Budding Yeast ◽  
Checkpoint Proteins ◽  
Cycle Arrest ◽  
Damage Response

One of the DNA damage-response mechanisms in budding yeast is temporary cell-cycle arrest while DNA repair takes place. The DNA damage response requires the coordinated interaction between DNA repair and checkpoint pathways. Telomeres of budding yeast are capped by the Cdc13 complex. In the temperature-sensitive cdc13-1 strain, telomeres are unprotected over a specific temperature range leading to activation of the DNA damage response and subsequently cell-cycle arrest. Inactivation of cdc13-1 results in the generation of long regions of single-stranded DNA (ssDNA) and is affected by the activity of various checkpoint proteins and nucleases. This paper describes a mathematical model of how uncapped telomeres in budding yeast initiate the checkpoint pathway leading to cell-cycle arrest. The model was encoded in the Systems Biology Markup Language (SBML) and simulated using the stochastic simulation system Biology of Ageing e-Science Integration and Simulation (BASIS). Each simulation follows the time course of one mother cell keeping track of the number of cell divisions, the level of activity of each of the checkpoint proteins, the activity of nucleases and the amount of ssDNA generated. The model can be used to carry out a variety of in silico experiments in which different genes are knocked out and the results of simulation are compared to experimental data. Possible extensions to the model are also discussed.

scholarly journals NRF2 preserves genomic integrity by facilitating ATR activation and G2 cell cycle arrest

2020 ◽  
Vol 48 (16) ◽  
pp. 9109-9123 ◽  
Author(s):  
Xiaohui Sun ◽  
Yan Wang ◽  
Kaihua Ji ◽  
Yang Liu ◽  
Yangyang Kong ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Cell Cycle Arrest ◽  
Cellular Response ◽  
Genome Stability ◽  
Related Factor ◽  
Dna Double Strand Breaks ◽  
Ros Scavenging ◽  
Cycle Arrest ◽  
G2 Cell Cycle Arrest

Abstract Nuclear factor erythroid 2-related factor 2 (NRF2) is a well-characterized transcription factor that protects cells against oxidative and electrophilic stresses. Emerging evidence has suggested that NRF2 protects cells against DNA damage by mechanisms other than antioxidation, yet the mechanism remains poorly understood. Here, we demonstrate that knockout of NRF2 in cells results in hypersensitivity to ionizing radiation (IR) in the presence or absence of reactive oxygen species (ROS). Under ROS scavenging conditions, induction of DNA double-strand breaks (DSBs) increases the NRF2 protein level and recruits NRF2 to DNA damage sites where it interacts with ATR, resulting in activation of the ATR–CHK1–CDC2 signaling pathway. In turn, this leads to G2 cell cycle arrest and the promotion of homologous recombination repair of DSBs, thereby preserving genome stability. The inhibition of NRF2 by brusatol increased the radiosensitivity of tumor cells in xenografts by perturbing ATR and CHK1 activation. Collectively, our results reveal a novel function of NRF2 as an ATR activator in the regulation of the cellular response to DSBs. This shift in perspective should help furnish a more complete understanding of the function of NRF2 and the DNA damage response.

scholarly journals Coordination of miR-192 and miR-22 in p53-Mediated Cell Fate Decision

2019 ◽  
Vol 20 (19) ◽  
pp. 4768 ◽  
Author(s):  
Cheng-Yuan Sun ◽  
Xiao-Peng Zhang ◽  
Wei Wang
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Cell Cycle Arrest ◽  
Cell Fate ◽  
Cellular Response ◽  
Cell Fate Decision ◽  
Tensin Homolog ◽  
P53 Signaling ◽  
Cycle Arrest ◽  
Fate Decision

p53-targeted microRNAs (miRNAs) markedly affect cellular response to DNA damage. These miRNAs may contribute to either cell cycle arrest or apoptosis induction. However, how these miRNAs coordinate to modulate the decision between cell survival and death remains less understood. Here, we developed an integrated model of p53 signaling network to investigate how p53-targeted miR-192 and miR-22 modulate cellular outcome in response to DNA damage. By numerical simulations, we found that p53 is activated progressively depending on the extent of DNA damage. Upon moderate damage, p53 rises to medium levels and induces miR-192 to promote its own activation, facilitating p21 induction and cell cycle arrest. Upon severe damage, p53 reaches high levels and is fully activated due to phosphatase and tensin homolog (PTEN) induction. As a result, it transactivates miR-22 to repress p21 expression and activate E2F1, resulting in apoptosis. Therefore, miR-192 promotes primary activation of p53, while miR-22 promotes apoptosis by downregulating p21. This work may advance the understanding of the mechanism for cell fate decision between life and death by p53-inducible miRNAs.

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