This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Rodríguez-Bravo, V. Articles by Agell, N. Search for Related Content PubMed PubMed Citation Articles by Rodríguez-Bravo, V. Articles by Agell, N.

Chk1- and Claspin-Dependent but ATR/ATM– and Rad17-Independent DNA Replication Checkpoint Response in HeLa Cells

Departament de Biologia Cel·lular i Anatomia Patològica, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Facultat de Medicina, Universitat de Barcelona, Barcelona, Spain

Requests for reprints: Neus Agell, Department Biologia Cel·lular, Facultat de Medicina, Universitat de Barcelona, C/Casanova, 143, 08036 Barcelona, Spain. Phone: 34-934035267; Fax: 34-934021907; E-mail: agell{at}medicina.ub.es.

When DNA synthesis is inhibited, DNA replication checkpoint is activated to prevent mitosis entry without fully replicated DNA. In Xenopus, caffeine-sensitive kinases [ataxia telangiectasia mutated (ATM) and ATM-related protein (ATR)] are essential in this checkpoint response, but in mammal cells an ATR/ATM–independent checkpoint response to DNA synthesis inhibition exists. Using HeLa cells, which have a caffeine-insensitive checkpoint response, we have analyzed here which molecules known to be involved in the DNA replication checkpoint participate in the caffeine-insensitive response. When DNA synthesis was inhibited in the presence of UCN01 or after knocking down Chk1 expression [Chk1 small interfering RNA (siRNA)], HeLa cells entered into aberrant mitosis. Consequently, Chk1 is essential for both the ATR/ATM–dependent and ATR/ATM–independent checkpoint response in HeLa cells. Neither wortmannin, Ly294002, nor SB202190 abrogated the caffeine-insensitive checkpoint response, indicating that DNA-PK and p38,ß are not involved in the ATR/ATM–independent Chk1 activation upon DNA synthesis inhibition. Using siRNA to knock down Rad17 and claspin, two molecules involved in sensing stalled replication forks, we also showed that claspin but not Rad17 is essential for the ATR/ATM–independent checkpoint response. Inhibition of DNA synthesis in HeLa cells led to a decrease in cyclin B1 protein accumulation that was abrogated when UCN01 was added or when claspin was knocked down. We conclude that upon DNA synthesis inhibition, Chk1 can be activated in a claspin-dependent manner independently of ATR and ATM, leading to cyclin B1 down-regulation and providing the cells of an additional mechanism to inhibit mitosis entry. (Cancer Res 2006; 66(17): 8672-9)

This article has been cited by other articles:

				J.-S. Im and J.-K. Lee ATR-dependent Activation of p38 MAP Kinase Is Responsible for Apoptotic Cell Death in Cells Depleted of Cdc7 J. Biol. Chem., September 12, 2008; 283(37): 25171 - 25177. [Abstract] [Full Text] [PDF]

				J.-H. Guervilly, G. Mace-Aime, and F. Rosselli Loss of CHK1 function impedes DNA damage-induced FANCD2 monoubiquitination but normalizes the abnormal G2 arrest in Fanconi anemia Hum. Mol. Genet., March 1, 2008; 17(5): 679 - 689. [Abstract] [Full Text] [PDF]

				V. Rodriguez-Bravo, S. Guaita-Esteruelas, N. Salvador, O. Bachs, and N. Agell Different S/M Checkpoint Responses of Tumor and Non Tumor Cell Lines to DNA Replication Inhibition Cancer Res., December 15, 2007; 67(24): 11648 - 11656. [Abstract] [Full Text] [PDF]

				S. Zhang, Y. Zhou, S. Trusa, X. Meng, E. Y. C. Lee, and M. Y. W. T. Lee A Novel DNA Damage Response: RAPID DEGRADATION OF THE p12 SUBUNIT OF DNA POLYMERASE {delta} J. Biol. Chem., May 25, 2007; 282(21): 15330 - 15340. [Abstract] [Full Text] [PDF]