Related Experiment Video
Updated: Aug 11, 2026
10:24
Two- and Three-Dimensional Live Cell Imaging of DNA Damage Response Proteins
Published on: September 28, 2012
Stalled replication induces p53 accumulation through distinct mechanisms from DNA damage checkpoint pathways
Chui Chui Ho1, Wai Yi Siu, Anita Lau
1Department of Biochemistry, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong.
Cancer Research
|February 21, 2006
Summary
Stalled replication forks stabilize p53 via pathways distinct from DNA damage. The replication checkpoint
Area of Science:
- Cellular Biology
- Molecular Biology
- Genetics
Background:
- Replication fork stalling triggers cellular responses, including p53 activation, crucial for maintaining the replication checkpoint.
- Mechanisms regulating p53 during replication stress differ from those activated by DNA damage, necessitating further investigation.
Purpose of the Study:
- To elucidate the upstream regulators and downstream effectors of p53 during replication blockade.
- To differentiate p53 stabilization pathways in response to DNA damage versus replication stress.
Main Methods:
- Hydroxyurea treatment to induce replication stress.
- Short-hairpin RNA-mediated knockdown of p21(CIP1/WAF1), CHK1, and CHK2.
- Analysis of p53 stabilization in ataxia telangiectasia cells and cells treated with caffeine.
- Assessment of p53 induction in cells deficient in NBS1 and BLM.
Main Results:
- Hydroxyurea increased p53 levels through enhanced protein stability, independent of p21(CIP1/WAF1).
- While the MRN-ATM/ATR-CHK1/CHK2 axis was activated, ATM was not critical for p53 stabilization.
- p53 induction by hydroxyurea was impaired in NBS1- and BLM-deficient cells, suggesting their involvement.
Conclusions:
- p53 stabilization during replication stress involves mechanisms distinct from DNA damage response pathways.
- The ATM-CHK1/CHK2 axis and p53-p21(CIP1/WAF1) pathway are not the primary mediators of the replication checkpoint.
- NBS1 and BLM play critical roles in p53 induction upon replication fork stalling.
Related Concept Videos
02:36DNA Damage can Stall the Cell Cycle
In response to DNA damage, cells can pause the cell cycle to assess and repair the breaks. However, the cell must check the DNA at certain critical stages during the cell cycle. If the cell cycle pauses before DNA replication, the cells will contain twice the amount of DNA. On the other hand, if cells arrest after DNA replication but before mitosis, they will contain four times the normal amount of DNA. With a host of specialized proteins at their disposal,cells must use the right protein at...
02:36DNA Damage Can Stall the Cell Cycle
In response to DNA damage, cells can pause the cell cycle to assess and repair the breaks. However, the cell must check the DNA at certain critical stages during the cell cycle. If the cell cycle pauses before DNA replication, the cells will contain twice the amount of DNA. On the other hand, if cells arrest after DNA replication but before mitosis, they will contain four times the normal amount of DNA. With a host of specialized proteins at their disposal,cells must use the right protein at...
02:37Restarting Stalled Replication Forks
DNA replication is initiated at sites containing predefined DNA sequences known as origins of replication. DNA is unwound at these sites by the minichromosome maintenance (MCM) helicase and other factors such as Cdc45 and the associated GINS complex.The unwound single strands are protected by replication protein A (RPA) until DNA polymerase starts synthesizing DNA at the 5’ end of the strand in the same direction as the replication fork. To prevent the replication fork from falling apart, a...
02:37Restarting Stalled Replication Forks
DNA replication is initiated at sites containing predefined DNA sequences known as origins of replication. DNA is unwound at these sites by the minichromosome maintenance (MCM) helicase and other factors such as Cdc45 and the associated GINS complex.The unwound single strands are protected by replication protein A (RPA) until DNA polymerase starts synthesizing DNA at the 5’ end of the strand in the same direction as the replication fork. To prevent the replication fork from falling apart, a...
01:23Negative Regulator Molecules
Positive regulators allow a cell to advance through cell cycle checkpoints. Negative regulators have an equally important role as they terminate a cell’s progression through the cell cycle—or pause it—until the cell meets specific criteria.
02:23Abnormal Proliferation
Under normal conditions, most adult cells remain in a non-proliferative state unless stimulated by internal or external factors to replace lost cells. Abnormal cell proliferation is a condition in which the cell's growth exceeds and is uncoordinated with normal cells. In such situations, cell division persists in the same excessive manner even after cessation of the stimuli, leading to persistent tumors. The tumor arises from the damaged cells that replicate to pass the damage to the daughter...