Related Experiment Video

Updated: Aug 17, 2026

Study of the DNA Damage Checkpoint using Xenopus Egg Extracts
10:55

Study of the DNA Damage Checkpoint using Xenopus Egg Extracts

Published on: November 5, 2012

PTEN loss inhibits CHK1 to cause double stranded-DNA breaks in cells

Janusz Puc1, Ramon Parsons

  • 1Institute for Cancer Genetics, Department of Pathology, Columbia University, New York, New York, USA.

Cell Cycle (Georgetown, Tex.)
|June 23, 2005
PubMed

Insights

Loss of PTEN causes DNA damage by inactivating CHK1 (Checkpoint Kinase 1), a key regulator of cell cycle and genomic integrity. This damage accumulation in PTEN-deficient cells may promote tumor development.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Cancer Research

Background:

  • Checkpoint Kinase 1 (CHK1) is crucial for cell cycle regulation and maintaining genomic stability.
  • Loss of PTEN function disrupts normal cellular processes, including DNA damage response pathways.
  • CHK1 activity is essential for preventing the accumulation of DNA breaks.

Purpose of the Study:

  • To investigate the consequences of PTEN loss on CHK1 function and DNA damage.
  • To elucidate the mechanisms by which PTEN deficiency leads to genomic instability.
  • To explore the link between CHK1 inactivation and tumor development in PTEN-deficient contexts.

Main Methods:

  • Analysis of CHK1 ubiquitination and phosphorylation sites.
  • Assessment of DNA double-strand breaks in PTEN-deficient cells.
  • Investigation of CHK1 localization and activity.

Main Results:

  • PTEN deficiency leads to the accumulation of double-stranded DNA breaks.
  • Loss of PTEN impairs CHK1-mediated checkpoint activation.
  • Ubiquitination of CHK1 at K274 and phosphorylation at S280 by AKT are critical events affected by PTEN loss.
  • Inappropriate CHK1 inactivation in PTEN-deficient cells results in DNA damage.

Conclusions:

  • Loss of PTEN causes DNA damage through the inappropriate inactivation of CHK1.
  • The interplay between PTEN, CHK1, and AKT signaling is vital for genomic integrity.
  • Accumulated DNA damage in PTEN-deficient cells may contribute to tumorigenesis.

More Related Videos

Tools to Study the Role of Architectural Protein HMGB1 in the Processing of Helix Distorting, Site-specific DNA Interstrand Crosslinks12:19

Tools to Study the Role of Architectural Protein HMGB1 in the Processing of Helix Distorting, Site-specific DNA Interstrand Crosslinks

Published on: November 10, 2016

Visualizing and Quantifying Endonuclease-Based Site-Specific DNA Damage10:59

Visualizing and Quantifying Endonuclease-Based Site-Specific DNA Damage

Published on: August 21, 2021

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.
Fixing Double-strand Breaks02:04

Fixing Double-strand Breaks

The double-stranded structure of DNA has two major advantages. First, it serves as a safe repository of genetic information where one strand serves as the back-up in case the other strand is damaged. Second, the double-helical structure can be wrapped around proteins called histones to form nucleosomes, which can then be tightly wound to form chromosomes. This way, DNA chains up to 2 inches long can be contained within microscopic structures in a cell. A double-stranded break not only damages...
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...
Restarting Stalled Replication Forks02:37

Restarting 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...
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...
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...