Related Experiment Video

Updated: Jun 23, 2026

Visualizing the DNA Damage Response in Purkinje Cells Using Cerebellar Organotypic Cultures
08:41

Visualizing the DNA Damage Response in Purkinje Cells Using Cerebellar Organotypic Cultures

Published on: December 27, 2024

Distinct roles of ATR and DNA-PKcs in triggering DNA damage responses in ATM-deficient cells

Nozomi Tomimatsu1, Bipasha Mukherjee, Sandeep Burma

  • 1Department of Radiation Oncology, Division of Molecular Radiation Biology, University of Texas Southwestern Medical Center, 2201 Inwood Road, NC7.214E, Dallas, Texas 75390, USA.

EMBO Reports
|May 16, 2009
PubMed

Insights

Ataxia telangiectasia mutated (ATM) and ataxia telangiectasia and Rad3 related (ATR) pathways respond to DNA double-strand breaks. ATR phosphorylates key checkpoint proteins independently of ATM, crucial for DNA repair in ATM-deficient cells.

Area of Science:

  • Molecular Biology
  • Cellular Biology
  • Genetics

Background:

  • DNA double-strand breaks trigger complex cellular responses involving ATM and ATR kinases.
  • ATM and ATR play critical roles in DNA damage checkpoints and genome stability.
  • Understanding the interplay between ATM and ATR is vital for comprehending DNA repair mechanisms.

Purpose of the Study:

  • To investigate the role of ATR in DNA double-strand break response, particularly in ATM-deficient cells.
  • To elucidate the mechanism of ATR-mediated phosphorylation of checkpoint proteins.
  • To determine the biological significance of ATR's function in the absence of ATM.

Main Methods:

  • Analysis of protein phosphorylation in response to DNA damage.
  • Cellular recruitment assays for DNA damage response proteins.
  • Assessment of cell-cycle checkpoints in ATM-deficient cells.

Main Results:

  • ATR phosphorylates key checkpoint proteins (p53, SMC1, 53BP1, Chk1, Chk2) independently of ATM, Mre11, and cell cycle status.
  • ATR and RPA sequentially recruit to DNA damage sites in ATM-deficient cells, dependent on Exo1 but not Mre11.
  • ATR is essential for ATR-dependent G2/M checkpoint activation and late G2 accumulation in irradiated ATM-deficient cells.
  • DNA-PKcs, in addition to ATM, phosphorylates KAP-1 involved in chromatin remodeling.

Conclusions:

  • ATR can minimally phosphorylate ATM substrates involved in cell-cycle checkpoint signaling independently of ATM.
  • ATR plays a critical role in DNA damage response and checkpoint control in ATM-deficient cells.
  • DNA-PKcs contributes to the phosphorylation of chromatin remodeling proteins alongside ATM.

More Related Videos

Characterizing DNA Repair Processes at Transient and Long-lasting Double-strand DNA Breaks by Immunofluorescence Microscopy08:31

Characterizing DNA Repair Processes at Transient and Long-lasting Double-strand DNA Breaks by Immunofluorescence Microscopy

Published on: June 8, 2018

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...
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...
Nucleotide Excision Repair01:08

Nucleotide Excision Repair

Overview
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...
Overview of DNA Repair02:25

Overview of DNA Repair

In order to be passed through generations, genomic DNA must be undamaged and error-free. However, every day, DNA in a cell undergoes several thousand to a million damaging events by natural causes and external factors. Ionizing radiation such as UV rays, free radicals produced during cellular respiration, and hydrolytic damage from metabolic reactions can alter the structure of DNA. Damages caused include single-base alteration, base dimerization, chain breaks, and cross-linkage.
Chemically...