QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Supplemental Research Data All Versions of this Article: gad.1398806v1 20/7/772    most recent Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend 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 Yoo, H. Y. Articles by Dunphy, W. G. Search for Related Content PubMed PubMed Citation Articles by Yoo, H. Y. Articles by Dunphy, W. G. Social Bookmarking                   What's this?

Site-specific phosphorylation of a checkpoint mediator protein controls its responses to different DNA structures

Division of Biology, California Institute of Technology, Pasadena, California 91125, USA

The checkpoint mediator protein Claspin is indispensable for the ATR-dependent phosphorylation of Chk1 in response to stalled DNA replication forks in Xenopus egg extracts. We show that Claspin also participates in the detection of chromosomal double-stranded DNA breaks (DSBs) in this system. Significantly, removal of Claspin from egg extracts only partially abrogates the activation of Chk1 in response to chromatin with DSBs, whereas depletion of both Claspin and BRCA1 completely abolishes this activation. The function of Claspin in this DSB-triggered pathway depends on phosphorylation of T817 and S819 by ATR. Conversely, neither phosphorylation of Claspin on these sites nor the presence of BRCA1 is necessary for activation of Chk1 in response to stalled replication forks. Thus, site-specific phosphorylation of a checkpoint mediator protein is a crucial determinant in the discrimination between various checkpoint-inducing structures. Furthermore, checkpoint mediator proteins exhibit functional overlap that varies depending on the nature of the checkpoint-triggering DNA signal.

[Keywords: Claspin; ATR; BRCA1; checkpoint control; Xenopus egg extract]

Received December 6, 2005; revised version accepted January 31, 2006.

² Corresponding author.

E-MAIL dunphy{at}cco.caltech.edu; FAX (626) 795-7563.

Supplemental material is available at http://www.genesdev.org.

Article published online ahead of print. Article and publication date are at http://www.genesdev.org/cgi/doi/10.1101/gad.1398806

CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				E. Petermann, T. Helleday, and K. W. Caldecott Claspin Promotes Normal Replication Fork Rates in Human Cells Mol. Biol. Cell, June 1, 2008; 19(6): 2373 - 2378. [Abstract] [Full Text] [PDF]

				H. Y. Yoo, A. Kumagai, A. Shevchenko, A. Shevchenko, and W. G. Dunphy Ataxia-telangiectasia Mutated (ATM)-dependent Activation of ATR Occurs through Phosphorylation of TopBP1 by ATM J. Biol. Chem., June 15, 2007; 282(24): 17501 - 17506. [Abstract] [Full Text] [PDF]

				L. Zou Single- and double-stranded DNA: building a trigger of ATR-mediated DNA damage response Genes & Dev., April 15, 2007; 21(8): 879 - 885. [Full Text] [PDF]

				G. Li, R. T. Elder, K. Qin, H. U. Park, D. Liang, and R. Y. Zhao Phosphatase Type 2A-dependent and -independent Pathways for ATR Phosphorylation of Chk1 J. Biol. Chem., March 9, 2007; 282(10): 7287 - 7298. [Abstract] [Full Text] [PDF]

				N. Yoshizawa-Sugata and H. Masai Human Tim/Timeless-interacting Protein, Tipin, Is Required for Efficient Progression of S Phase and DNA Replication Checkpoint J. Biol. Chem., January 26, 2007; 282(4): 2729 - 2740. [Abstract] [Full Text] [PDF]

				C. C. S. Chini and J. Chen Repeated Phosphopeptide Motifs in Human Claspin Are Phosphorylated by Chk1 and Mediate Claspin Function J. Biol. Chem., November 3, 2006; 281(44): 33276 - 33282. [Abstract] [Full Text] [PDF]