Related Experiment Video

Updated: Aug 6, 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

Requirement for p53 and p21 to sustain G2 arrest after DNA damage

F Bunz1, A Dutriaux, C Lengauer

  • 1The Howard Hughes Medical Institute and The Johns Hopkins Oncology Center, 424 North Bond Street, Baltimore, MD 21231, USA.

Science (New York, N.Y.)
|November 20, 1998
PubMed

Insights

The p53 and p21 proteins are crucial for maintaining the G2 cell cycle checkpoint after DNA damage. Without functional p53 or p21, cells fail to arrest properly, leading to cell division errors.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Genetics

Background:

  • DNA damage triggers a cell cycle arrest at the G2 phase to allow for DNA repair.
  • The p53 tumor suppressor protein and its downstream target p21 are key regulators of cell cycle checkpoints.

Purpose of the Study:

  • To investigate the role of p53 and p21 in sustaining the G2 cell cycle arrest following DNA damage.
  • To determine the necessity of p53 and p21 for proper G2 checkpoint function in human cells.

Main Methods:

  • Utilizing gene disruption of p53 and p21 in human cells.
  • Inducing DNA damage using gamma radiation.
  • Analyzing cell cycle progression and cytokinesis through observation of cell morphology and DNA content.

Main Results:

  • Sustained G2 arrest was dependent on the presence and transcriptional activity of p53, which activates p21.
  • Disruption of p53 or p21 genes led to premature entry into mitosis despite DNA damage.
  • Cells lacking functional p53 or p21 exhibited G2 DNA content due to failed cytokinesis, not a proper arrest.

Conclusions:

  • The p53-p21 pathway is essential for maintaining the G2 checkpoint in human cells after DNA damage.
  • p53 and p21 are critical for preventing aberrant cell division and ensuring genomic stability.

More Related Videos

Visualization of DNA Repair Proteins Interaction by Immunofluorescence07:55

Visualization of DNA Repair Proteins Interaction by Immunofluorescence

Published on: June 26, 2020

Visualizing Single-Stranded DNA Foci in the G1 Phase of the Cell Cycle08:30

Visualizing Single-Stranded DNA Foci in the G1 Phase of the Cell Cycle

Published on: December 22, 2023

Related Concept Videos

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.
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...
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...
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...
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...
The Cell Cycle Control System01:28

The Cell Cycle Control System

The cell cycle regulation directs how a cell proceeds from one phase to the next and begins mitosis. The cell cycle control system includes intracellular regulatory molecules and external triggers. They provide "stop" or "advance" signals and operate at specific cell cycle stages termed checkpoints to ensure that a particular process is completed before the cell advances to the next phase.
Cyclins and cyclin-dependent kinases (Cdks) are the primary cell cycle regulators and function at the cell...