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p53 protein at the hub of cellular DNA damage response pathways through sequence-specific and non-sequence-specific
1Department of Dermatology and Oregon Cancer Center, Oregon Health Sciences University, Portland, OR 97201, USA.
Abstract:
Our environment contains physical, chemical and pathological agents that challenge the integrity of our DNA. In addition to DNA repair, higher multicellular organisms have evolved multiple pathways of response to damage including programmed cell death-apoptosis. The p53 protein appears to sense multiple types of DNA damage and coordinate with multiple options for cellular response. The p53 protein activities depend upon its DNA binding. Specific p53 protein post-translational modifications are required for efficient sequence-specific binding and transcriptional activities. Non-sequence-specific DNA binding may involve a wide spectrum of p53 proteins and predominate as DNA damage is more severe or p53 protein is more highly induced. p53 protein is not strictly required for DNA damage sensing and repair. Rather, p53 protein may govern an apoptosis checkpoint through competition with DNA repair proteins for non-sequence-specific binding to exposed single-stranded regions in the DNA duplex. This model provides a framework for testing mechanisms of p53-mediated apoptosis dependent upon the p53 protein modification state, the level of p53 protein accumulation, the level of DNA damage and the capacity of the damaged cell to repair.
Insights
The p53 protein coordinates cellular responses to DNA damage, including apoptosis. Its DNA binding, modified by post-translational changes, influences sequence-specific and non-sequence-specific interactions, governing the apoptosis checkpoint.
Area of Science:
- Molecular Biology
- Cellular Biology
- Genetics
Background:
- Environmental agents constantly challenge DNA integrity.
- Multicellular organisms utilize DNA repair and apoptosis to respond to DNA damage.
- The p53 protein is a key mediator in sensing DNA damage and orchestrating cellular responses.
Purpose of the Study:
- To elucidate the role of p53 protein in DNA damage response pathways.
- To investigate the mechanisms of p53-mediated apoptosis.
- To establish a framework for analyzing p53's function based on its modification state and DNA binding.
Main Methods:
- Analysis of p53 protein's DNA binding activities (sequence-specific and non-sequence-specific).
- Investigation of p53 protein post-translational modifications.
- Modeling p53's role in the apoptosis checkpoint and competition with DNA repair proteins.
Main Results:
- p53 protein's sequence-specific DNA binding and transcriptional activity are dependent on specific post-translational modifications.
- Non-sequence-specific DNA binding by p53 protein increases with severe DNA damage or high p53 induction.
- p53 protein may regulate apoptosis by competing with DNA repair proteins for binding to damaged DNA.
Conclusions:
- p53 protein acts as a crucial sensor and coordinator of cellular responses to DNA damage.
- The modification state and accumulation level of p53 protein critically influence its function in apoptosis.
- A model is proposed where p53 governs an apoptosis checkpoint through differential DNA binding.