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ATR enforces the topoisomerase II-dependent G(2) checkpoint through inhibition of Plk1 kinase

Deming, PB, Flores, KG, Downes, Stephen, Paules, RS and Kaufmann, WK (2002) ATR enforces the topoisomerase II-dependent G(2) checkpoint through inhibition of Plk1 kinase. JOURNAL OF BIOLOGICAL CHEMISTRY, 277 (39). pp. 36832-36838. [Journal article]

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DOI: 10.1074/jbc.M206109200


An ATR-dependent G(2) checkpoint responds to inhibition of topoisomerase 11 and delays entry into mitosis by sustaining nuclear exclusion of cyclin B1-Cdk1 complexes. Here we report that induction of this checkpoint with ICRF-193, a topoisomerase H catalytic inhibitor that does not cause DNA damage, was associated with an ATR-dependent inhibition of polo-like kinase 1 (Plk1) kinase activity and a decrease in cyclin B1 phosphorylation. Expression of constitutively active Plk1 but not wild type Plk1 reversed ICRF-193-induced mitotic delay in HeLa cells, suggesting that Plk1 kinase activity is important for the checkpoint response to ICRF-193. G(2)/M synchronized normal human fibroblasts, when treated with ICRF-193, showed a decrease in cyclin B1 phosphorylation and Plk1 kinase activity despite high cyclin B1-Cdk1 kinase activity. G(2) fibroblasts that were treated with caffeine to override the checkpoint response to ICRF-193 displayed a high incidence of chromosomal aberrations. Taken together, these results suggest that ATR-dependent inhibition of Plk1 kinase activity may be one mechanism to regulate cyclin B1 phosphorylation and sustain nuclear exclusion during the G(2) checkpoint response to topoisomerase 11 inhibition. Moreover, the results demonstrate an important role for the topoisomerase II-dependent G(2) checkpoint in the preservation of human genomic stability.

Item Type:Journal article
Faculties and Schools:Faculty of Life and Health Sciences
Faculty of Life and Health Sciences > School of Biomedical Sciences
Research Institutes and Groups:Biomedical Sciences Research Institute
Biomedical Sciences Research Institute > Genomic Medicine
ID Code:3394
Deposited By: Professor Stephen Downes
Deposited On:15 Dec 2009 11:49
Last Modified:08 May 2017 16:04

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