scholarly journals Poly(ADP-ribose) binding to Chk1 at stalled replication forks is required for S-phase checkpoint activation

2013 ◽  
Vol 4 (1) ◽  
Author(s):  
WooKee Min ◽  
Christopher Bruhn ◽  
Paulius Grigaravicius ◽  
Zhong-Wei Zhou ◽  
Fu Li ◽  
...  
Keyword(s):  
S Phase ◽  
Replication Forks ◽  
Checkpoint Activation ◽  
Stalled Replication Forks ◽  
S Phase Checkpoint

scholarly journals hCLK2 couples FANCD2 to stalled replication forks and functions in the mammalian S-phase checkpoint

2006 ◽  
Vol 8 (S2) ◽  
Author(s):  
SJ Collis ◽  
LJ Barber ◽  
JS Martin ◽  
JD Ward ◽  
SJ Boulton
Keyword(s):  
S Phase ◽  
Replication Forks ◽  
Stalled Replication Forks ◽  
S Phase Checkpoint

scholarly journals The Intra-S Phase Checkpoint Targets Dna2 to Prevent Stalled Replication Forks from Reversing

Cell ◽  
2012 ◽  
Vol 149 (6) ◽  
pp. 1221-1232 ◽  
Author(s):  
Jiazhi Hu ◽  
Lei Sun ◽  
Fenfen Shen ◽  
Yufei Chen ◽  
Yu Hua ◽  
...  
Keyword(s):  
S Phase ◽  
Replication Forks ◽  
Stalled Replication Forks ◽  
S Phase Checkpoint

scholarly journals Intra-S-Phase Checkpoint Activation by Direct CDK2 Inhibition

2004 ◽  
Vol 24 (14) ◽  
pp. 6268-6277 ◽  
Author(s):  
Yonghong Zhu ◽  
Carmen Alvarez ◽  
Ronald Doll ◽  
Hirokazu Kurata ◽  
Xiao Min Schebye ◽  
...  
Keyword(s):  
Genomic Stability ◽  
S Phase ◽  
Cell Cycle Checkpoints ◽  
Minichromosome Maintenance ◽  
Checkpoint Activation ◽  
Cdk2 Activity ◽  
A Cell ◽  
Dependent Pathway ◽  
Number Of Cells ◽  
S Phase Checkpoint

ABSTRACT To ensure proper progression through a cell cycle, checkpoints have evolved to play a surveillance role in maintaining genomic integrity. In this study, we demonstrate that loss of CDK2 activity activates an intra-S-phase checkpoint. CDK2 inhibition triggers a p53-p21 response via ATM- and ATR-dependent p53 phosphorylation at serine 15. Phosphorylation of other ATM and ATR downstream substrates, such as H2AX, NBS1, CHK1, and CHK2 is also increased. We show that during S phase when CDK2 activity is inhibited, there is an unexpected loading of the minichromosome maintenance complex onto chromatin. In addition, there is an increased number of cells with more than 4N DNA content, detected in the absence of p53, suggesting that rereplication can occur as a result of CDK2 disruption. Our findings identify an important role for CDK2 in the maintenance of genomic stability, acting via an ATM- and ATR-dependent pathway.

scholarly journals Divergent S Phase Checkpoint Activation Arising from Prereplicative Complex Deficiency Controls Cell Survival

2009 ◽  
Vol 20 (17) ◽  
pp. 3953-3964 ◽  
Author(s):  
Eric Lau ◽  
Gary G. Chiang ◽  
Robert T. Abraham ◽  
Wei Jiang
Keyword(s):  
Dna Replication ◽  
Cancer Cells ◽  
S Phase ◽  
Checkpoint Control ◽  
Multiple Cancer ◽  
Checkpoint Activation ◽  
Diploid Cells ◽  
Prereplicative Complex ◽  
Stress Damage ◽  
S Phase Checkpoint

The DNA replication machinery plays additional roles in S phase checkpoint control, although the identities of the replication proteins involved in checkpoint activation remain elusive. Here, we report that depletion of the prereplicative complex (pre-RC) protein Cdc6 causes human nontransformed diploid cells to arrest nonlethally in G1-G1/S and S phase, whereas multiple cancer cell lines undergo G1-G1/S arrest and cell death. These divergent phenotypes are dependent on the activation, or lack thereof, of an ataxia telangiectasia and Rad3-related (ATR)-dependent S phase checkpoint that inhibits replication fork progression. Although pre-RC deficiency induces chromatin structural alterations in both nontransformed and cancer cells that normally lead to ATR checkpoint activation, the sensor mechanisms in cancer cells seem to be compromised such that higher levels of DNA replication stress/damage are required to trigger checkpoint response. Our results suggest that therapy-induced disruption of pre-RC function might exert selective cytotoxic effects on tumor cells in human patients.

scholarly journals Exo1 phosphorylation inhibits exonuclease activity and prevents fork collapse in rad53 mutants independently of the 14-3-3 proteins

2020 ◽  
Vol 48 (6) ◽  
pp. 3053-3070
Author(s):  
Esther C Morafraile ◽  
Alberto Bugallo ◽  
Raquel Carreira ◽  
María Fernández ◽  
Cristina Martín-Castellanos ◽  
...  
Keyword(s):  
Genome Stability ◽  
Nuclease Activity ◽  
S Phase ◽  
Exonuclease Activity ◽  
Replication Forks ◽  
Post Translational Modifications ◽  
Replicative Stress ◽  
Stalled Replication Forks ◽  
Maintain Genome Stability ◽  
Specific Contribution

Abstract The S phase checkpoint is crucial to maintain genome stability under conditions that threaten DNA replication. One of its critical functions is to prevent Exo1-dependent fork degradation, and Exo1 is phosphorylated in response to different genotoxic agents. Exo1 seemed to be regulated by several post-translational modifications in the presence of replicative stress, but the specific contribution of checkpoint-dependent phosphorylation to Exo1 control and fork stability is not clear. We show here that Exo1 phosphorylation is Dun1-independent and Rad53-dependent in response to DNA damage or dNTP depletion, and in both situations Exo1 is similarly phosphorylated at multiple sites. To investigate the correlation between Exo1 phosphorylation and fork stability, we have generated phospho-mimic exo1 alleles that rescue fork collapse in rad53 mutants as efficiently as exo1-nuclease dead mutants or the absence of Exo1, arguing that Rad53-dependent phosphorylation is the mayor requirement to preserve fork stability. We have also shown that this rescue is Bmh1–2 independent, arguing that the 14-3-3 proteins are dispensable for fork stabilization, at least when Exo1 is downregulated. Importantly, our results indicated that phosphorylation specifically inhibits the 5' to 3'exo-nuclease activity, suggesting that this activity of Exo1 and not the flap-endonuclease, is the enzymatic activity responsible of the collapse of stalled replication forks in checkpoint mutants.

scholarly journals The intra-S phase checkpoint directly regulates replication elongation to preserve the integrity of stalled replisomes

2021 ◽  
Vol 118 (24) ◽  
pp. e2019183118
Author(s):  
Yang Liu ◽  
Lu Wang ◽  
Xin Xu ◽  
Yue Yuan ◽  
Bo Zhang ◽  
...  
Keyword(s):  
Fission Yeast ◽  
Dna Polymerases ◽  
Replication Stress ◽  
Underlying Mechanism ◽  
S Phase ◽  
Replication Forks ◽  
Helicase Activity ◽  
Replicative Helicase ◽  
Checkpoint Kinases ◽  
S Phase Checkpoint

DNA replication is dramatically slowed down under replication stress. The regulation of replication speed is a conserved response in eukaryotes and, in fission yeast, requires the checkpoint kinases Rad3ATR and Cds1Chk2. However, the underlying mechanism of this checkpoint regulation remains unresolved. Here, we report that the Rad3ATR-Cds1Chk2 checkpoint directly targets the Cdc45-MCM-GINS (CMG) replicative helicase under replication stress. When replication forks stall, the Cds1Chk2 kinase directly phosphorylates Cdc45 on the S275, S322, and S397 residues, which significantly reduces CMG helicase activity. Furthermore, in cds1Chk2-mutated cells, the CMG helicase and DNA polymerases are physically separated, potentially disrupting replisomes and collapsing replication forks. This study demonstrates that the intra-S phase checkpoint directly regulates replication elongation, reduces CMG helicase processivity, prevents CMG helicase delinking from DNA polymerases, and therefore helps preserve the integrity of stalled replisomes and replication forks.

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