Chk2 activation dependence on Nbs1 after DNA damage

Buscemi, G., Savio, C., Zannini, L., Micciche, F., Masnada, D., Nakanishi, M., Tauchi, H., Komatsu, S., Mizutani, S., Khanna, K., Chen, P., Concannon, P., Chessa, L. and Delia, D. (2001) Chk2 activation dependence on Nbs1 after DNA damage. Molecular & Cellular Biology, 21 15: 5214-5222. doi:10.1128/MCB.21.15.5214-5222.2001

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Author Buscemi, G.
Savio, C.
Zannini, L.
Micciche, F.
Masnada, D.
Nakanishi, M.
Tauchi, H.
Komatsu, S.
Mizutani, S.
Khanna, K.
Chen, P.
Concannon, P.
Chessa, L.
Delia, D.
Title Chk2 activation dependence on Nbs1 after DNA damage
Journal name Molecular & Cellular Biology   Check publisher's open access policy
ISSN 0270-7306
Publication date 2001
Sub-type Article (original research)
DOI 10.1128/MCB.21.15.5214-5222.2001
Open Access Status File (Publisher version)
Volume 21
Issue 15
Start page 5214
End page 5222
Total pages 9
Place of publication Washington, DC, United States
Publisher American Society for Microbiology
Collection year 2001
Language eng
Abstract The checkpoint kinase Chk2 has a key role in delaying cell cycle progression in response to DNA damage. Upon activation by low-dose ionizing radiation (IR), which occurs in an ataxia telangiectasia mutated (ATM)dependent manner, Chk2 can phosphorylate the mitosis-inducing phosphatase Cdc25C on an inhibitory site, blocking entry into mitosis, and p53 on a regulatory site, causing G, arrest. Here we show that the ATM-dependent activation of Chk2 by gamma- radiation requires Nbs1, the gene product involved in the Nijmegen breakage syndrome (NBS), a disorder that shares with AT a variety of phenotypic defects including chromosome fragility, radiosensitivity, and radioresistant DNA synthesis. Thus, whereas in normal cells Chk2 undergoes a time-dependent increased phosphorylation and induction of catalytic activity against Cdc25C, in NBS cells null for Nbs1 protein, Chk2 phosphorylation and activation are both defective. Importantly, these defects in NBS cells can be complemented by reintroduction of wild-type Nbs1, but neither by a carboxy-terminal deletion mutant of Nbs1 at amino acid 590, unable to form a complex with and to transport Mre11 and Rad50 in the nucleus, nor by an Nbs1 mutated at Ser343 (S343A), the ATM phosphorylation site. Chk2 nuclear expression is unaffected in NBS cells, hence excluding a mislocalization as the cause of failed Chk2 activation in Nbs1-null cells, interestingly, the impaired Chk2 function in NBS cells correlates with the inability, unlike normal cells, to stop entry into mitosis immediately after irradiation, a checkpoint abnormality that can be corrected by introduction of the wild-type but not the S343A mutant form of Nbs1, Altogether, these findings underscore the crucial role of a functional Nbs1 complex in Chk2 activation and suggest that checkpoint defects in NBS cells may result from the inability to activate Chk2.
Keyword Biochemistry & Molecular Biology
Cell Biology
Nijmegen Breakage Syndrome
Cell-cycle Checkpoints
Spindle Checkpoint
Defective Control
Protein Complex
Syndrome Gene
Atm Protein
Q-Index Code C1

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Medicine Publications
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Citation counts: TR Web of Science Citation Count  Cited 164 times in Thomson Reuters Web of Science Article | Citations
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Created: Tue, 14 Aug 2007, 16:37:44 EST