Related Experiment Videos
Induction of p53-, MDM2-, and WAF1/CIP1-like molecules in insect cells by DNA-damaging agents
I Bae1, M L Smith, A J Fornace
1Laboratory of Molecular Pharmacology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
Abstract:
Cellular responses following DNA damage are ubiquitous in the biological world. In response to DNA damage, cell cycle checkpoints are activated, which delay cell cycle progression and most likely serve to allow time for repair. One important checkpoint in mammalian cells, activated in the G1 phase of the cell cycle, is dependent on the p53 tumor suppressor gene product. While p53 is responsible for inducing G1 arrest, the product of the MDM2 gene is believed to alleviate the arrest, allowing continuation of the cell cycle after a transient delay. Inasmuch as MDM2 and WAF1/CIP1 are transactivated by p53, while MDM2 binds to and modulates the activity of p53, a "feedback loop" is thus created. This pathway has been highly conserved in mammalian cells, but its presence outside of vertebrates is unknown. By using human MDM2 and WAF1/CIP1 cDNA probes, and monoclonal antibodies to p53 and Mdm2, we demonstrate in insect cell lines evidence for the existence of p53-, MDM2-, and WAF1/CIP1-like molecules and a p53-regulated pathway following treatment by DNA-damaging agents.
Insights
This study reveals that insect cells possess molecules similar to human p53, MDM2, and WAF1/CIP1. These findings suggest a conserved DNA damage response pathway exists beyond vertebrates.
Area of Science:
- Molecular Biology
- Cell Biology
- Genetics
Background:
- Cell cycle checkpoints are crucial for DNA repair following damage.
- The p53 tumor suppressor protein and its regulators (MDM2, WAF1/CIP1) form a conserved pathway in mammals.
- The evolutionary conservation of this pathway outside vertebrates is unknown.
Purpose of the Study:
- To investigate the presence of p53-MDM2-WAF1/CIP1 pathway components in non-vertebrate organisms.
- To determine if DNA-damaging agents can activate a similar pathway in insect cells.
Main Methods:
- Utilized human MDM2 and WAF1/CIP1 cDNA probes for molecular analysis.
- Employed monoclonal antibodies against p53 and Mdm2 for protein detection.
- Treated insect cell lines with DNA-damaging agents.
Main Results:
- Detected p53-, MDM2-, and WAF1/CIP1-like molecules in insect cell lines.
- Demonstrated the activation of a p53-regulated pathway in response to DNA damage in these cells.
- Provided evidence for functional conservation of the DNA damage response pathway.
Conclusions:
- The p53-regulated DNA damage response pathway, involving p53, MDM2, and WAF1/CIP1, is not exclusive to vertebrates.
- This pathway appears to be conserved in insects, suggesting an ancient evolutionary origin.
- Insect cells exhibit cellular responses to DNA damage mediated by these conserved molecules.