Cell-cycle checkpoints are signal transduction pathways that ensure orderly progression of the cell cycle, and that proliferating cells do not attempt to replicate or segregate damaged chromosomes. Recent studies have pinpointed two members of the P1 3-kinase related kinase family, ATM and ATR, as proximal signaling elements in the G1, S, and G2 checkpoint pathways. The emerging view is that ATM function is required for the induction of appropriate checkpoint responses to ionizing radiation-induced DNA double-strand breaks, while ATR plays dominant roles in the responses to ultraviolet light induced DNA damage, as well as to DNA replicative stress induced by drugs or intrinsic errors associated with DNA metabolism. In spite of this progress, the mechanisms underlying the regulation and function of ATR remain unclear, due in large part to the lack of a genetically tractable, ATR-deficient cellular model system. Similarly, although our preliminary studies have identified two important genome surveillance proteins, BRCA1 and hRad17, as substrates for the ATM/ATR kinases in DNA-damaged cells, the functional consequences of these phosphorylation events have not been defined. This project will address these critical issues through implementation of the following specific aims: (1) To complete the generation of a novel ATR-/- cell line, and to characterize the checkpoint signaling defects in these cells, and (2) To determine the impact of ATR-mediated phosphorylation on the genome maintenance functions of BRCA1, through the use of two newly described functional assays for BRCA1, (3) To define the regulatory effects of ATR/ATM-dependent phosphorylation on the checkpoint signaling functions of hRad17, and (4) To identify and functionally characterize novel SIT-Q-containing substrates for ATR and ATM in cells exposed to genotoxic stress.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA097950-02
Application #
6640664
Study Section
Radiation Study Section (RAD)
Program Officer
Pelroy, Richard
Project Start
2002-03-01
Project End
2006-02-28
Budget Start
2003-03-01
Budget End
2004-02-29
Support Year
2
Fiscal Year
2003
Total Cost
$396,495
Indirect Cost
Name
Sanford-Burnham Medical Research Institute
Department
Type
DUNS #
020520466
City
La Jolla
State
CA
Country
United States
Zip Code
92037
Lau, Eric; Chiang, Gary G; Abraham, Robert T et al. (2009) Divergent S phase checkpoint activation arising from prereplicative complex deficiency controls cell survival. Mol Biol Cell 20:3953-64
Oliveira, Vasco; Romanow, William J; Geisen, Christoph et al. (2008) A protective role for the human SMG-1 kinase against tumor necrosis factor-alpha-induced apoptosis. J Biol Chem 283:13174-84
Lau, Eric; Tsuji, Toshiya; Guo, Liping et al. (2007) The role of pre-replicative complex (pre-RC) components in oncogenesis. FASEB J 21:3786-94
Lau, Eric; Zhu, Changjun; Abraham, Robert T et al. (2006) The functional role of Cdc6 in S-G2/M in mammalian cells. EMBO Rep 7:425-30
Lau, Eric; Jiang, Wei (2006) Is there a pre-RC checkpoint that cancer cells lack? Cell Cycle 5:1602-6
Zhang, You-Wei; Hunter, Tony; Abraham, Robert T (2006) Turning the replication checkpoint on and off. Cell Cycle 5:125-8
Zhang, You-Wei; Otterness, Diane M; Chiang, Gary G et al. (2005) Genotoxic stress targets human Chk1 for degradation by the ubiquitin-proteasome pathway. Mol Cell 19:607-18
Ali, Ambereen; Zhang, Ji; Bao, Shideng et al. (2004) Requirement of protein phosphatase 5 in DNA-damage-induced ATM activation. Genes Dev 18:249-54
Abraham, Robert T (2004) The ATM-related kinase, hSMG-1, bridges genome and RNA surveillance pathways. DNA Repair (Amst) 3:919-25
Chiang, Gary G; Abraham, Robert T (2004) Determination of the catalytic activities of mTOR and other members of the phosphoinositide-3-kinase-related kinase family. Methods Mol Biol 281:125-41

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