ATR Pathway Is the Primary Pathway for Activating G2/M Checkpoint Induction After Re-replication

Jin, Lin; Dutta, Anindya

doi:10.1074/jbc.m705178200

Cited by 62 publications

(68 citation statements)

References 45 publications

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“…Instead, our results suggest that abnormal chromatin structure resulting from aberrant DNA replication due to pre-RC deficiency might be a trigger for S phase checkpoint activation. Recently, chromatin alterations have been shown to play an important role for ATR-checkpoint activation, because deregulation of DNA licensing and alteration of chromatin structure indicated by changes of HP1␣ localization, activate S phase checkpoint signaling cascades (Davidson et al, 2006;Lin and Dutta, 2007;Ayoub et al, 2008). Similar chromatin structural alterations also were observed in Orc2 depletion or carcinogen/replication inhibitor studies, where inhibition of new origin firing, replication/chromatin structural alterations, checkpoint activation, and reduced replication rates were reported (Prasanth et al, 2004b;Conti et al, 2007a).…”

Section: Pre-rc Deficiency and Atr-dependent Checkpoint Activationsupporting

confidence: 50%

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

Lau

Chiang

Abraham

et al. 2009

MBoC

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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. INTRODUCTIONIn all eukaryotic cells, DNA replication initiates from multiple replication origins throughout the genome, and each segment of DNA replicates only once per cell cycle. Primary regulation of DNA replication is exerted at the initiation of DNA synthesis, when replication origins are licensed by assembly of prereplication complexes (pre-RCs) in early G1 (Bell and Dutta, 2002;Blow and Dutta, 2005). This process begins with origin recognition complex (ORC) binding to a nascent replication origin, resulting in recruitment of the loading factors Cdc6, and Cdt1, which function together to load the putative DNA replicative helicase minichromosomal maintenance (MCM) complex. Subsequently, phosphorylation of pre-RC and other DNA replication factors by the S phase-promoting kinases, cyclin-dependent kinases and Dbf4-dependent kinase Cdc7, in G1/S and S promotes loading of Cdc45, MCM10, GINS, RPA, and DNA polymerases to the pre-RC/origin, triggering the initiation of DNA replication.DNA replication fidelity is ensured by S phase checkpoint mechanisms that monitor aberrant DNA replication, replication stress, DNA damage, and chromatin structure alterations in S phase. The S phase checkpoints are mainly governed by the phosphoinositide 3-kinase-related kinases (PIKKs) ataxia telangiectasia mutated-(ATM) or ataxia telangiectasia and Rad3-related (ATR)-dependent signaling pathways. On activation, the ATM/ATR checkpoint pathways immediately suppress late origin firing to prevent further DNA replication and stabilize stalled replication forks to ensure proper replication restart once the replication block/DNA damage has been repaired or removed. Although the ATM-dependent checkpoint responds to DNA double-strand breaks (DSBs), the ATR-dependent checkpoint responds to a broad spectrum of DNA lesions, such as single-strand breaks, fork stalling, or chromatin structural alterations (Abraham, 2001;Yang and Zou, 2006;Cimprich and Cortez, 2008). Th...

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Section: Pre-rc Deficiency and Atr-dependent Checkpoint Activationsupporting

confidence: 50%

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

Lau

Chiang

Abraham

et al. 2009

MBoC

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“…It also should be noted that Gem79-130 had little effect on Chk1 phosphorylation induced by GST-Cdt1, suggesting that the checkpoint pathway effectively repressed repetitive origin firing under these conditions. Thus, these observations suggest that there are at least two mechanisms that inhibit the extensive rereplication induced by licensing in S phase, one of which depends on ATR and the Chk1-directed checkpoint machinery Lin and Dutta, 2007;Liu et al, 2007) and the other, which is a Cdt1-induced pathway independent of the checkpoint machinery, as indicated by Davidson et al (2006), which is sensitive to Gem79-130. …”

mentioning

confidence: 99%

“…Recently, it was reported that ATM and Rad3-related (ATR)/Chk1, but not ataxia telangiectasia mutated (ATM)/Chk2, prevents rereplication Lin and Dutta, 2007;Liu et al, 2007), presumably because ATR/Chk1 suppresses the Cdk2 activity required for the initiation of rereplication (Abraham, 2001;Luciani et al, 2004). Checkpoint activation also requires multiple rounds of rereplication, suggesting that activation is induced by the aberrant DNA structures created by multiple replication forks (Davidson et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Repression of Nascent Strand Elongation by Deregulated Cdt1 during DNA Replication inXenopusEgg Extracts

Tsuyama

Watanabe

Aoki

et al. 2009

MBoC

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Excess Cdt1 reportedly induces rereplication of chromatin in cultured cells and Xenopus egg extracts, suggesting that the regulation of Cdt1 activity by cell cycle-dependent proteolysis and expression of the Cdt1 inhibitor geminin is crucial for the inhibition of chromosomal overreplication between S phase and metaphase. We analyzed the consequences of excess Cdt1 for DNA replication and found that increased Cdt1 activity inhibited the elongation of nascent strands in Xenopus egg extracts. In Cdt1-supplemented extracts, overreplication was remarkably induced by the further addition of the Cdt1-binding domain of geminin (Gem79-130), which lacks licensing inhibitor activity. Further analyses indicated that fully active geminin, as well as Gem79-130, restored nascent strand elongation in Cdt1-supplemented extracts even after the Cdt1-induced stalling of replication fork elongation had been established. Our results demonstrate an unforeseen, negative role for Cdt1 in elongation and suggest that its function in the control of replication should be redefined. We propose a novel surveillance mechanism in which Cdt1 blocks nascent chain elongation after detecting illegitimate activation of the licensing system. INTRODUCTIONTo maintain genome integrity, chromosomes are precisely duplicated only once per cell division cycle. In eukaryotic cells, the replication licensing system ensures accurate DNA replication. The prereplication complex associates with origins of replication before S phase through the stepwise assembly of the origin recognition complex, Cdc6, Cdt1, and Mcm2-7, after which licensing takes place (Diffley, 2004;Blow and Dutta, 2006). Mcm2-7 is thought to act as the replicative helicase, and the loading of Mcm2-7 onto chromatin is considered to be the key initiating event of the licensing reaction (Pacek and Walter, 2004). Licensed origins are presumably activated in S phase by Cdc7-and cyclindependent kinase (CDK)-dependent processes, leading to the formation of replication forks and the recruitment of DNA polymerases.Repression of licensing after the onset of S phase is crucial for preventing rereplication (Fujita, 2006;Arias and Walter, 2007). In fission yeast, overexpression of Cdc18, an orthologue of Cdc6 in budding yeast and higher eukaryotes, induces rereplication (Nishitani et al., 2000;Yanow et al., 2001), suggesting that Cdc18/Cdc6 is a major target of mechanisms that repress licensing. In contrast, Cdt1 seems to be the crucial target in higher eukaryotes, because unregulated Cdt1 activity alone induces rereplication (Vaziri et al., 2003;Nishitani et al., 2004;Li and Blow, 2005;Arias and Walter, 2005;Maiorano et al., 2005). Geminin represses licensing by binding and inhibiting Cdt1 (Wohlschlegel et al., 2000;Tada et al., 2001), and it is inactivated or degraded on mitotic exit (McGarry and Kirschner, 1998;Li and Blow, 2004). The nuclear import of geminin during S phase reactivates it to restrict licensing (Hodgson et al., 2002;Yoshida et al., 2005). Crystallographic analysis revealed that geminin f...

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“…The deletion of the ATR gene causes early embryonic lethality in mice, and the mutation of this gene results in Seckel syndrome, which is characterized by a defective DNA damage response (10)(11)(12). Loss of ATR function also inhibits phosphorylation of downstream effectors such as p53 and Chk1 and leads to apoptosis (6,13). These facts indicate that ATR is essential for cell survival, development, and DNA damage response pathways (10,11).…”

Section: Introductionmentioning

confidence: 94%

“…IR is a well-known inducer of DNA double strand break. Hydroxyurea, a competitive inhibitor of ribonucleotide reductase, blocks DNA replication, resulting in ATR activation (13,32). HCT116-Mock and HCT116-COX-2 cells were exposed to graded doses of IR or hydroxyurea, and then cell viability was monitored by a clonogenic assay.…”

Section: Hct116-cox-2 Cells Containing Elevated Atr Are Resistant To mentioning

confidence: 99%

Cyclooxygenase-2 Up-Regulates Ataxia Telangiectasia and Rad3 Related through Extracellular Signal-Regulated Kinase Activation

Kim

Lee

Park

et al. 2009

Molecular Cancer Research

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Cyclooxygenase-2 (COX-2) overexpression caused prolonged G 2 arrest after exposure to ionizing radiation (IR) in our previous study. We were therefore interested in investigating the function of COX-2 in the G 2 checkpoint pathway. Interestingly, we found that cells in which COX-2 is overexpressed showed up-regulated ataxia telangiectasia and Rad3 related (ATR) expression compared with control cells. In this study, we investigated the mechanism of ATR up-regulation by COX-2 and tested our hypothesis that COX-2-induced extracellular signal-regulated kinase (ERK) activation mediates up-regulation of ATR by COX-2. To investigate the relationship between COX-2 and ATR, we used two stable COX-2-overexpressing cancer cell lines (HCT116-COX-2 and H460-COX-2), a COX-2 knockdown A549 lung cancer cell line (AS), and an ATR knockdown HCT116 cell line. Cells were treated with various drugs [celecoxib, prostaglandin E 2 (PGE 2 ), PD98059, U0126, and hydroxyurea] and were then analyzed using reverse transcription-PCR, confocal microscopy, Western blotting, and clonogenic assay. COX-2-overexpressing cells were shown to have increased ERK phosphorylation and ATR expression compared with control cells, whereas AS cells were shown to have decreased levels of phospho-ERK and ATR. In addition, exogenously administered PGE 2 increased ERK phosphorylation. Inhibition of ERK phosphorylation decreased ATR expression in both HCT116-COX-2 and A549 cells. HCT116-COX-2 cells were resistant to IR or hydroxyurea compared with HCT116-Mock cells, whereas administration of ATR shRNA showed the opposite effect. COX-2 stimulates ERK phosphorylation via PGE 2 . This COX-2-induced ERK activation seems to increase ATR expression and activity in endogenous COX-2-overexpressing cancer cells as well as in COX-2-overexpressing stable cell

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ATR Pathway Is the Primary Pathway for Activating G2/M Checkpoint Induction After Re-replication

Cited by 62 publications

References 45 publications

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

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

Repression of Nascent Strand Elongation by Deregulated Cdt1 during DNA Replication inXenopusEgg Extracts

Cyclooxygenase-2 Up-Regulates Ataxia Telangiectasia and Rad3 Related through Extracellular Signal-Regulated Kinase Activation

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