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Analysis of DNA Double-strand Break (DSB) Repair in Mammalian Cells
Published on: September 8, 2010
A telomeric repeat sequence adjacent to a DNA double-stranded break produces an anticheckpoint
Rhett J Michelson1, Saul Rosenstein, Ted Weinert
1Molecular and Cellular Biology Department, University of Arizona, Tucson, Arizona 85721, USA.
Genes & Development
|October 19, 2005
Summary
Telomeres possess an anticheckpoint activity that prevents cell cycle arrest from nearby DNA damage. This activity, observed in Saccharomyces cerevisiae, allows faster recovery from double-strand breaks adjacent to telomeric repeats.
Area of Science:
- Molecular Biology
- Cell Biology
- Genetics
Background:
- Telomeres are essential protective structures at chromosome ends.
- Cell cycle checkpoints prevent proliferation upon DNA damage detection.
Purpose of the Study:
- To investigate the potential anticheckpoint activity of telomeres in Saccharomyces cerevisiae.
- To determine if telomeric repeats can inhibit DNA damage checkpoint signaling.
Main Methods:
- Induction of double-strand breaks (DSBs) adjacent to telomeric repeat tracts in yeast.
- Monitoring of cell cycle arrest duration and checkpoint protein (Rad9, Rad53) phosphorylation status.
- Assessing the effect of telomeric repeats on DSBs located on separate chromosomes.
Main Results:
- Internal telomeric repeats significantly reduced cell cycle arrest duration from adjacent DSBs (1-2 h vs. 8-12 h).
- This abridged arrest was not due to DNA repair, reduced single-stranded DNA, or adaptation.
- The anticheckpoint activity acts regionally, inhibiting signaling from nearby DSBs but not those on other chromosomes.
Conclusions:
- Telomeres in Saccharomyces cerevisiae exhibit an anticheckpoint activity that suppresses DNA damage signaling.
- This telomere-associated activity may involve inhibition of Mec1 (ATR ortholog), leading to Rad9 and Rad53 inactivation.
- A mature telomere likely forms rapidly after DSB formation, contributing proteins that inhibit nearby checkpoint signaling.
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