UV Irradiation Causes the Loss of Viable Mitotic Recombinants in Schizosaccharomyces pombe Cells Lacking the G2/M DNA Damage Checkpoint

Genetics ◽  
2002 ◽  
Vol 160 (3) ◽  
pp. 891-908
Author(s):  
Fekret Osman ◽  
Irina R Tsaneva ◽  
Matthew C Whitby ◽  
Claudette L Doe
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Schizosaccharomyces Pombe ◽  
Uv Irradiation ◽  
Cellular Responses ◽  
Replication Forks ◽  
Uv Damage ◽  
Checkpoint Proteins ◽  
Recombinant Frequency ◽  
Dna Damage Checkpoints

Abstract Elevated mitotic recombination and cell cycle delays are two of the cellular responses to UV-induced DNA damage. Cell cycle delays in response to DNA damage are mediated via checkpoint proteins. Two distinct DNA damage checkpoints have been characterized in Schizosaccharomyces pombe: an intra-S-phase checkpoint slows replication and a G2/M checkpoint stops cells passing from G2 into mitosis. In this study we have sought to determine whether UV damage-induced mitotic intrachromosomal recombination relies on damage-induced cell cycle delays. The spontaneous and UV-induced recombination phenotypes were determined for checkpoint mutants lacking the intra-S and/or the G2/M checkpoint. Spontaneous mitotic recombinants are thought to arise due to endogenous DNA damage and/or intrinsic stalling of replication forks. Cells lacking only the intra-S checkpoint exhibited no UV-induced increase in the frequency of recombinants above spontaneous levels. Mutants lacking the G2/M checkpoint exhibited a novel phenotype; following UV irradiation the recombinant frequency fell below the frequency of spontaneous recombinants. This implies that, as well as UV-induced recombinants, spontaneous recombinants are also lost in G2/M mutants after UV irradiation. Therefore, as well as lack of time for DNA repair, loss of spontaneous and damage-induced recombinants also contributes to cell death in UV-irradiated G2/M checkpoint mutants.

scholarly journals Role of Schizosaccharomyces pombe RecQ homolog, recombination, and checkpoint genes in UV damage tolerance.

1997 ◽  
Vol 17 (12) ◽  
pp. 6868-6875 ◽  
Author(s):  
J M Murray ◽  
H D Lindsay ◽  
C A Munday ◽  
A M Carr
Keyword(s):  
Dna Damage ◽  
Schizosaccharomyces Pombe ◽  
Replication Fork ◽  
Cellular Responses ◽  
Gene Products ◽  
Uv Damage ◽  
Checkpoint Genes ◽  
Mutant Cells ◽  
Cell Lethality

The cellular responses to DNA damage are complex and include direct DNA repair pathways that remove the damage and indirect damage responses which allow cells to survive DNA damage that has not been, or cannot be, removed. We have identified the gene mutated in the rad12.502 strain as a Schizosaccharomyces pombe recQ homolog. The same gene (designated rqh1) is also mutated in the hus2.22 mutant. We show that Rqhl is involved in a DNA damage survival mechanism which prevents cell death when UV-induced DNA damage cannot be removed. This pathway also requires the correct functioning of the recombination machinery and the six checkpoint rad gene products plus the Cdsl kinase. Our data suggest that Rqh1 operates during S phase as part of a mechanism which prevents DNA damage causing cell lethality. This process may involve the bypass of DNA damage sites by the replication fork. Finally, in contrast with the reported literature, we do not find that rqh1 (rad12) mutant cells are defective in UV dimer endonuclease activity.

DNA replication and damage checkpoints and meiotic cell cycle controls in the fission and budding yeasts

2000 ◽  
Vol 349 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Hiroshi MURAKAMI ◽  
Paul NURSE
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Dna Replication ◽  
Fission Yeast ◽  
Molecular Mechanisms ◽  
Cell Cycle Checkpoint ◽  
Cell Cycle Regulators ◽  
Meiotic Cell ◽  
Checkpoint Proteins ◽  
Dna Damage Checkpoints

The cell cycle checkpoint mechanisms ensure the order of cell cycle events to preserve genomic integrity. Among these, the DNA-replication and DNA-damage checkpoints prevent chromosome segregation when DNA replication is inhibited or DNA is damaged. Recent studies have identified an outline of the regulatory networks for both of these controls, which apparently operate in all eukaryotes. In addition, it appears that these checkpoints have two arrest points, one is just before entry into mitosis and the other is prior to chromosome separation. The former point requires the central cell-cycle regulator Cdc2 kinase, whereas the latter involves several key regulators and substrates of the ubiquitin ligase called the anaphase promoting complex. Linkages between these cell-cycle regulators and several key checkpoint proteins are beginning to emerge. Recent findings on post-translational modifications and protein-protein interactions of the checkpoint proteins provide new insights into the checkpoint responses, although the functional significance of these biochemical properties often remains unclear. We have reviewed the molecular mechanisms acting at the DNA-replication and DNA-damage checkpoints in the fission yeast Schizosaccharomyces pombe, and the modifications of these controls during the meiotic cell cycle. We have made comparisons with the controls in fission yeast and other organisms, mainly the distantly related budding yeast.

scholarly journals Proapoptotic p53-Interacting Protein 53BP2 Is Induced by UV Irradiation but Suppressed by p53

2000 ◽  
Vol 20 (21) ◽  
pp. 8018-8025 ◽  
Author(s):  
Charles D. Lopez ◽  
Yi Ao ◽  
Larry H. Rohde ◽  
Tomas D. Perez ◽  
Daniel J. O'Connor ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Cell Lines ◽  
Uv Irradiation ◽  
Cellular Response ◽  
Clonogenic Survival ◽  
Uv Damage ◽  
Wild Type ◽  
Interacting Protein ◽  
Conditional Expression

ABSTRACT p53 is an important mediator of the cellular stress response with roles in cell cycle control, DNA repair, and apoptosis. 53BP2, a p53-interacting protein, enhances p53 transactivation, impedes cell cycle progression, and promotes apoptosis through unknown mechanisms. We now demonstrate that endogenous 53BP2 levels increase following UV irradiation induced DNA damage in a p53-independent manner. In contrast, we found that the presence of a wild-type (but not mutant) p53 gene suppressed 53BP2 steady-state levels in cell lines with defined p53 genotypes. Likewise, expression of a tetracycline-regulated wild-type p53 cDNA in p53-null fibroblasts caused a reduction in 53BP2 protein levels. However, 53BP2 levels were not reduced if the tetracycline-regulated p53 cDNA was expressed after UV damage in these cells. This suggests that UV damage activates cellular factors that can relieve the p53-mediated suppression of 53BP2 protein. To address the physiologic significance of 53BP2 induction, we utilized stable cell lines with a ponasterone A-regulated 53BP2 cDNA. Conditional expression of 53BP2 cDNA lowered the apoptotic threshold and decreased clonogenic survival following UV irradiation. Conversely, attenuation of endogenous 53BP2 induction with an antisense oligonucleotide resulted in enhanced clonogenic survival following UV irradiation. These results demonstrate that 53BP2 is a DNA damage-inducible protein that promotes DNA damage-induced apoptosis. Furthermore, 53BP2 expression is highly regulated and involves both p53-dependent and p53-independent mechanisms. Our data provide new insight into 53BP2 function and open new avenues for investigation into the cellular response to genotoxic stress.

scholarly journals Recruitment of DNA Damage Checkpoint Proteins to Damage in Transcribed and Nontranscribed Sequences

2006 ◽  
Vol 26 (1) ◽  
pp. 39-49 ◽  
Author(s):  
Guochun Jiang ◽  
Aziz Sancar
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Excision Repair ◽  
Dna Lesions ◽  
Human Cells ◽  
Dna Damage Checkpoint ◽  
Damage Site ◽  
Checkpoint Response ◽  
Checkpoint Proteins ◽  
Transcription Complexes

ABSTRACT We developed a chromatin immunoprecipitation method for analyzing the binding of repair and checkpoint proteins to DNA base lesions in any region of the human genome. Using this method, we investigated the recruitment of DNA damage checkpoint proteins RPA, Rad9, and ATR to base damage induced by UV and acetoxyacetylaminofluorene in transcribed and nontranscribed regions in wild-type and excision repair-deficient human cells in G1 and S phases of the cell cycle. We find that all 3 damage sensors tested assemble at the site or in the vicinity of damage in the absence of DNA replication or repair and that transcription enhances recruitment of checkpoint proteins to the damage site. Furthermore, we find that UV irradiation of human cells defective in excision repair leads to phosphorylation of Chk1 kinase in both G1 and S phase of the cell cycle, suggesting that primary DNA lesions as well as stalled transcription complexes may act as signals to initiate the DNA damage checkpoint response.

A superfamily of conserved domains in DNA damage‐ responsive cell cycle checkpoint proteins

1997 ◽  
Vol 11 (1) ◽  
pp. 68-76 ◽  
Author(s):  
Peer Bork ◽  
Kay Hofmann ◽  
Philipp Bucher ◽  
Andrew F. Neuwald ◽  
Stephen F. Altschul ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Cell Cycle Checkpoint ◽  
Conserved Domains ◽  
Checkpoint Proteins ◽  
Cycle Checkpoint ◽  
Responsive Cell

Role of the Saccharomyces cerevisiae Rad9 protein in sensing and responding to DNA damage

2003 ◽  
Vol 31 (1) ◽  
pp. 242-246 ◽  
Author(s):  
G.W.-L. Toh ◽  
N.F. Lowndes
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Damage ◽  
Cellular Responses ◽  
Eukaryotic Cells ◽  
Genome Damage ◽  
Dna Damage Checkpoints ◽  
Repair Mechanisms ◽  
Sense And Respond ◽  
Insight Into

Eukaryotic cells have evolved surveillance mechanisms, known as DNA-damage checkpoints, that sense and respond to genome damage. DNA-damage checkpoint pathways ensure co-ordinated cellular responses to DNA damage, including cell cycle delays and activation of repair mechanisms. RAD9, from Saccharomyces cerevisiae, was the first damage checkpoint gene to be identified, although its biochemical function remained unknown until recently. This review examines briefly work that provides significant insight into how Rad9 activates the checkpoint signalling kinase Rad53.

scholarly journals DNA damage checkpoint dynamics drive cell cycle phase transitions

2017 ◽  
Author(s):  
Hui Xiao Chao ◽  
Cere E. Poovey ◽  
Ashley A. Privette ◽  
Gavin D. Grant ◽  
Hui Yan Chao ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Phase Transitions ◽  
Cell Cycle Progression ◽  
S Phase ◽  
Cell Cycle Phase ◽  
Cycle Phase ◽  
Dna Damage Checkpoint ◽  
Cycle Progression ◽  
Dna Damage Checkpoints

ABSTRACTDNA damage checkpoints are cellular mechanisms that protect the integrity of the genome during cell cycle progression. In response to genotoxic stress, these checkpoints halt cell cycle progression until the damage is repaired, allowing cells enough time to recover from damage before resuming normal proliferation. Here, we investigate the temporal dynamics of DNA damage checkpoints in individual proliferating cells by observing cell cycle phase transitions following acute DNA damage. We find that in gap phases (G1 and G2), DNA damage triggers an abrupt halt to cell cycle progression in which the duration of arrest correlates with the severity of damage. However, cells that have already progressed beyond a proposed “commitment point” within a given cell cycle phase readily transition to the next phase, revealing a relaxation of checkpoint stringency during later stages of certain cell cycle phases. In contrast to G1 and G2, cell cycle progression in S phase is significantly less sensitive to DNA damage. Instead of exhibiting a complete halt, we find that increasing DNA damage doses leads to decreased rates of S-phase progression followed by arrest in the subsequent G2. Moreover, these phase-specific differences in DNA damage checkpoint dynamics are associated with corresponding differences in the proportions of irreversibly arrested cells. Thus, the precise timing of DNA damage determines the sensitivity, rate of cell cycle progression, and functional outcomes for damaged cells. These findings should inform our understanding of cell fate decisions after treatment with common cancer therapeutics such as genotoxins or spindle poisons, which often target cells in a specific cell cycle phase.

scholarly journals Caffeine Stabilises Fission Yeast Wee1 in a Rad24-Dependent Manner but Attenuates Its Expression in Response to DNA Damage

2020 ◽  
Vol 8 (10) ◽  
pp. 1512
Author(s):  
John P. Alao ◽  
Johanna Johansson-Sjölander ◽  
Charalampos Rallis ◽  
Per Sunnerhagen
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Stress Response ◽  
Environmental Stress ◽  
Cell Cycle Progression ◽  
Dependent Manner ◽  
Environmental Stress Response ◽  
Cycle Progression ◽  
Dna Damage Checkpoints ◽  
Wee1 Kinase

The widely consumed neuroactive compound caffeine has generated much interest due to its ability to override the DNA damage and replication checkpoints. Previously Rad3 and its homologues was thought to be the target of caffeine’s inhibitory activity. Later findings indicate that the Target of Rapamycin Complex 1 (TORC1) is the preferred target of caffeine. Effective Cdc2 inhibition requires both the activation of the Wee1 kinase and inhibition of the Cdc25 phosphatase. The TORC1, DNA damage, and environmental stress response pathways all converge on Cdc25 and Wee1. We previously demonstrated that caffeine overrides DNA damage checkpoints by modulating Cdc25 stability. The effect of caffeine on cell cycle progression resembles that of TORC1 inhibition. Furthermore, caffeine activates the Sty1 regulated environmental stress response. Caffeine may thus modulate multiple signalling pathways that regulate Cdc25 and Wee1 levels, localisation and activity. Here we show that the activity of caffeine stabilises both Cdc25 and Wee1. The stabilising effect of caffeine and genotoxic agents on Wee1 was dependent on the Rad24 chaperone. Interestingly, caffeine inhibited the accumulation of Wee1 in response to DNA damage. Caffeine may modulate cell cycle progression through increased Cdc25 activity and Wee1 repression following DNA damage via TORC1 inhibition, as TORC1 inhibition increased DNA damage sensitivity.

Sign in / Sign up

Export Citation Format

Share Document