Cdc5L interacts with ATR and is required for the S‐phase cell‐cycle checkpoint

Abstract Although it is well established that plant seeds treated with high doses of gamma radiation arrest development as seedlings, the cause of this arrest is unknown. The uvh1 mutant of Arabidopsis is defective in a homolog of the human repair endonuclease XPF, and uvh1 mutants are sensitive to both the toxic effects of UV and the cytostatic effects of gamma radiation. Here we find that gamma irradiation of uvh1 plants specifically triggers a G2-phase cell cycle arrest. Mutants, termed suppressor of gamma (sog), that suppress this radiation-induced arrest and proceed through the cell cycle unimpeded were recovered in the uvh1 background; the resulting irradiated plants are genetically unstable. The sog mutations fall into two complementation groups. They are second-site suppressors of the uvh1 mutant's sensitivity to gamma radiation but do not affect the susceptibility of the plant to UV radiation. In addition to rendering the plants resistant to the growth inhibitory effects of gamma radiation, the sog1 mutation affects the proper development of the pollen tetrad, suggesting that SOG1 might also play a role in the regulation of cell cycle progression during meiosis.

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Attenuation of G 2 -Phase Cell Cycle Checkpoint Control Is Associated with Increased Frequencies of Unrejoined Chromosome Breaks in Human Tumor Cells

Radiation Research ◽

10.2307/3579585 ◽

1996 ◽

Vol 146 (2) ◽

pp. 139 ◽

Cited By ~ 7

Author(s):

Jeffrey L. Schwartz ◽

Janet Cowan ◽

David J. Grdina ◽

Ralph R. Weichselbaum

Keyword(s):

Cell Cycle ◽

Tumor Cells ◽

Human Tumor ◽

Cell Cycle Checkpoint ◽

Phase Cell ◽

Checkpoint Control ◽

Human Tumor Cells ◽

Chromosome Breaks ◽

Cycle Checkpoint

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Critical Role for Mouse Hus1 in an S-Phase DNA Damage Cell Cycle Checkpoint

Molecular and Cellular Biology ◽

10.1128/mcb.23.3.791-803.2003 ◽

2003 ◽

Vol 23 (3) ◽

pp. 791-803 ◽

Cited By ~ 50

Author(s):

Robert S. Weiss ◽

Philip Leder ◽

Cyrus Vaziri

Keyword(s):

Cell Cycle ◽

Dna Damage ◽

Dna Synthesis ◽

Critical Role ◽

S Phase ◽

Cell Cycle Checkpoint ◽

Dna Damage Checkpoint ◽

Null Mouse ◽

Cycle Checkpoint ◽

S Phase Checkpoint

ABSTRACT Mouse Hus1 encodes an evolutionarily conserved DNA damage response protein. In this study we examined how targeted deletion of Hus1 affects cell cycle checkpoint responses to genotoxic stress. Unlike hus1− fission yeast (Schizosaccharomyces pombe) cells, which are defective for the G2/M DNA damage checkpoint, Hus1-null mouse cells did not inappropriately enter mitosis following genotoxin treatment. However, Hus1-deficient cells displayed a striking S-phase DNA damage checkpoint defect. Whereas wild-type cells transiently repressed DNA replication in response to benzo(a)pyrene dihydrodiol epoxide (BPDE), a genotoxin that causes bulky DNA adducts, Hus1-null cells maintained relatively high levels of DNA synthesis following treatment with this agent. However, when treated with DNA strand break-inducing agents such as ionizing radiation (IR), Hus1-deficient cells showed intact S-phase checkpoint responses. Conversely, checkpoint-mediated inhibition of DNA synthesis in response to BPDE did not require NBS1, a component of the IR-responsive S-phase checkpoint pathway. Taken together, these results demonstrate that Hus1 is required specifically for one of two separable mammalian checkpoint pathways that respond to distinct forms of genome damage during S phase.

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