Title |
Chk1 regulates the S phase checkpoint by coupling the physiological turnover and ionizing radiation-induced accelerated proteolysis of Cdc25A
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Published in |
Cancer Cell, March 2003
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DOI | 10.1016/s1535-6108(03)00048-5 |
Pubmed ID | |
Authors |
Claus Storgaard Sørensen, Randi G. Syljuåsen, Jacob Falck, Tine Schroeder, Lars Rönnstrand, Kum Kum Khanna, Bin-Bing Zhou, Jiri Bartek, Jiri Lukas |
Abstract |
Chk1 kinase coordinates cell cycle progression and preserves genome integrity. Here, we show that chemical or genetic ablation of human Chk1 triggered supraphysiological accumulation of the S phase-promoting Cdc25A phosphatase, prevented ionizing radiation (IR)-induced degradation of Cdc25A, and caused radioresistant DNA synthesis (RDS). The basal turnover of Cdc25A operating in unperturbed S phase required Chk1-dependent phosphorylation of serines 123, 178, 278, and 292. IR-induced acceleration of Cdc25A proteolysis correlated with increased phosphate incorporation into these residues generated by a combined action of Chk1 and Chk2 kinases. Finally, phosphorylation of Chk1 by ATM was required to fully accelerate the IR-induced degradation of Cdc25A. Our results provide evidence that the mammalian S phase checkpoint functions via amplification of physiologically operating, Chk1-dependent mechanisms. |
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Researcher | 36 | 14% |
Student > Master | 34 | 13% |
Student > Bachelor | 27 | 11% |
Student > Doctoral Student | 15 | 6% |
Other | 28 | 11% |
Unknown | 41 | 16% |
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Pharmacology, Toxicology and Pharmaceutical Science | 4 | 2% |
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