Related Experiment Video

Updated: Jul 2, 2026

Two- and Three-Dimensional Live Cell Imaging of DNA Damage Response Proteins
10:24

Two- and Three-Dimensional Live Cell Imaging of DNA Damage Response Proteins

Published on: September 28, 2012

p53 Binding to the p21 promoter is dependent on the nature of DNA damage

Richard Hill1, Ewelina Bodzak, Michael D Blough

  • 1Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada.

Cell Cycle (Georgetown, Tex.)
|August 23, 2008
PubMed

Insights

The tumor suppressor p53

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Genetics

Background:

  • p53 is a crucial tumor suppressor protein that regulates critical cellular processes like cell cycle arrest, apoptosis, and DNA repair in response to various stress signals.
  • The precise mechanisms by which p53 dictates cell fate remain incompletely understood.
  • p21, a transcriptional target of p53, plays a vital role in cell cycle control and apoptosis, mediating anti-apoptotic responses after DNA damage.

Purpose of the Study:

  • To investigate and compare the p53-dependent transcriptional regulation of p21 following DNA damage induced by ultraviolet (UV) radiation versus ionizing radiation (IR).
  • To elucidate how differential promoter engagement and post-translational modifications of p53 influence p21 expression and cellular outcomes after distinct DNA damage types.

Main Methods:

  • Comparative analysis of p53 and p21 protein accumulation and degradation kinetics after UV and IR exposure.
  • Chromatin immunoprecipitation (ChIP) assays to assess p53 binding to the p21 promoter.
  • Analysis of p53 post-translational modifications and histone acetylation at the p21 promoter region.

Main Results:

  • Ionizing radiation (IR) induced significantly earlier and higher accumulation of p21 protein compared to ultraviolet (UV) radiation, despite similar p53 accumulation levels.
  • Both UV and IR induced p21 protein degradation, but differential post-damage transcription accounted for the observed disparities in p21 protein levels.
  • p53 exhibited promoter bias, showing reduced binding to the p21 promoter in UV-damaged cells versus IR-damaged cells, linked to decreased histone acetylation at the p21 promoter's TATA box after UV treatment.

Conclusions:

  • The type of DNA damage influences p53's transcriptional activity, demonstrating selective promoter discrimination.
  • Differential p53 binding and promoter accessibility, modulated by post-translational modifications and chromatin states, underlie the distinct p21 induction patterns after UV and IR.
  • These findings provide insights into how p53 fine-tunes cellular responses to different DNA damage types, impacting cell fate decisions.

More Related Videos

Yeast As a Chassis for Developing Functional Assays to Study Human P5314:57

Yeast As a Chassis for Developing Functional Assays to Study Human P53

Published on: August 4, 2019

Detection and Visualization of DNA Damage-induced Protein Complexes in Suspension Cell Cultures Using the Proximity Ligation Assay13:10

Detection and Visualization of DNA Damage-induced Protein Complexes in Suspension Cell Cultures Using the Proximity Ligation Assay

Published on: June 9, 2017

Related Concept Videos

DNA Damage can Stall the Cell Cycle02:36

DNA 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...
DNA Damage Can Stall the Cell Cycle02:36

DNA 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...
Negative Regulator Molecules01:23

Negative 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.
Abnormal Proliferation02:23

Abnormal 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...
Inhibition of Cdk Activity02:34

Inhibition of Cdk Activity

The orderly progression of the cell cycle depends on the activation of Cdk protein by binding to its cyclin partner. However, the cell cycle must be restricted when undergoing abnormal changes. Most cancers correlate to the deregulated cell cycle, and since Cdks are a central component of the cell cycle, Cdk inhibitors are extensively studied to develop anticancer agents. For instance, cyclin D associates with several Cdks, such as Cdk 4/6, to form an active complex. The cyclin D-Cdk4/6 complex...
Nucleotide Excision Repair01:38

Nucleotide Excision Repair

DNA Distortion and Damage
Cells are regularly exposed to mutagens—factors in the environment that can damage DNA and generate mutations. UV radiation is one of the most common mutagens and is estimated to introduce a significant number of changes in DNA. These include bends or kinks in the structure, which can block DNA replication or transcription. If these errors are not fixed, the damage can cause mutations, which in turn can result in cancer or disease depending on which sequences are...