HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 281, Issue 41, 30631-30644, October 13, 2006

This Article Full Text Full Text (PDF) All Versions of this Article: 281/41/30631    most recent M602982200v1 Submit a Letter to Editor Alert me when this article is cited Alert me when eLetters are posted 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 Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Liu, P. Articles by Vaziri, C. Search for Related Content PubMed PubMed Citation Articles by Liu, P. Articles by Vaziri, C. Social Bookmarking                      What's this?

The Chk1-mediated S-phase Checkpoint Targets Initiation Factor Cdc45 via a Cdc25A/Cdk2-independent Mechanism^*

Peijun Liu, Laura R. Barkley, Tovah Day, Xiaohui Bi, Damien M. Slater, Mark G. Alexandrow, Heinz-Peter Nasheuer^¶, and Cyrus Vaziri¹

From the Department of Genetics and Genomics, Boston University School of Medicine, Boston, Massachusetts 02118, the H. Lee Moffitt Cancer Center & Research Institute, University of South Florida, Tampa, Florida 33612, and the ^¶Department of Biochemistry, Cell Cycle Control Laboratory, National University of Ireland, Galway, Ireland

DNA damage induced by the carcinogen benzo[a]pyrene dihydrodiol epoxide (BPDE) induces a Chk1-dependent S-phase checkpoint. Here, we have investigated the molecular basis of BPDE-induced S-phase arrest. Chk1-dependent inhibition of DNA synthesis in BPDE-treated cells occurred without detectable changes in Cdc25A levels, Cdk2 activity, or Cdc7/Dbf4 interaction. Overexpression studies showed that Cdc25A, cyclin A/Cdk2, and Cdc7/Dbf4 were not rate-limiting for DNA synthesis when the BPDE-induced S-phase checkpoint was active. To investigate other potential targets of the S-phase checkpoint, we tested the effects of BPDE on the chromatin association of DNA replication factors. The levels of chromatin-associated Cdc45 (but not soluble Cdc45) were reduced concomitantly with BPDE-induced Chk1 activation and inhibition of DNA synthesis. The chromatin association of Mcm7, Mcm10, and proliferating cell nuclear antigen was unaffected by BPDE treatment. However, the association between Mcm7 and Cdc45 in the chromatin fraction was inhibited in BPDE-treated cells. Chromatin immunoprecipitation analyses demonstrated reduced association of Cdc45 with the -globin origin of replication in BPDE-treated cells. The inhibitory effects of BPDE on DNA synthesis, Cdc45/Mcm7 associations, and interactions between Cdc45 and the -globin locus were abrogated by the Chk1 inhibitor UCN-01. Taken together, our results show that the association between Cdc45 and Mcm7 at origins of replication is negatively regulated by Chk1 in a Cdk2-independent manner. Therefore, Cdc45 is likely to be an important target of the Chk1-mediated S-phase checkpoint.

Received for publication, March 29, 2006 , and in revised form, July 31, 2006.

^* This work was supported in part by Philip Morris USA and Philip Morris International, by National Institutes of Health Grants ES09558 and ES12917 (to C. V.), and by Deutsche Forschungsgemeinschaft Grant SFB604-B2 and Health Research Board Ireland Grant RP/2003/133 (to H.-P. N.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

¹ To whom correspondence should be addressed: Dept. of Genetics and Genomics, Boston University School of Medicine, 715 Albany St., E633, Boston, MA 02118. Tel.: 617-638-4175; Fax: 617-414-1646; E-mail: cvaziri{at}bu.edu.

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

This article has been cited by other articles:

				J. Scorah, M.-Q. Dong, J. R. Yates III, M. Scott, D. Gillespie, and C. H. McGowan A Conserved Proliferating Cell Nuclear Antigen-interacting Protein Sequence in Chk1 Is Required for Checkpoint Function J. Biol. Chem., June 20, 2008; 283(25): 17250 - 17259. [Abstract] [Full Text] [PDF]

				S. K. Srivastava, P. Bansal, T. Oguri, J. S. Lazo, and S. V. Singh Cell Division Cycle 25B Phosphatase Is Essential for Benzo(a)Pyrene-7,8-Diol-9,10-Epoxide Induced Neoplastic Transformation Cancer Res., October 1, 2007; 67(19): 9150 - 9157. [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]

				K. Unsal-Kacmaz, P. D. Chastain, P.-P. Qu, P. Minoo, M. Cordeiro-Stone, A. Sancar, and W. K. Kaufmann The Human Tim/Tipin Complex Coordinates an Intra-S Checkpoint Response to UV That Slows Replication Fork Displacement Mol. Cell. Biol., April 15, 2007; 27(8): 3131 - 3142. [Abstract] [Full Text] [PDF]

				T. P. Heffernan, K. Unsal-Kacmaz, A. N. Heinloth, D. A. Simpson, R. S. Paules, A. Sancar, M. Cordeiro-Stone, and W. K. Kaufmann Cdc7-Dbf4 and the Human S Checkpoint Response to UVC J. Biol. Chem., March 30, 2007; 282(13): 9458 - 9468. [Abstract] [Full Text] [PDF]