Related Experiment Video

Updated: Aug 9, 2026

Visualization of DNA Repair Proteins Interaction by Immunofluorescence
07:55

Visualization of DNA Repair Proteins Interaction by Immunofluorescence

Published on: June 26, 2020

Disruption of the Rad9/Rad1/Hus1 (9-1-1) complex leads to checkpoint signaling and replication defects

Shilai Bao1, Tao Lu, Xin Wang

  • 1Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.

Oncogene
|June 9, 2004
PubMed

Insights

The Rad9/Rad1/Hus1 complex is vital for DNA damage response. Loss of Rad1 disrupts this complex, impairing cell cycle control and genomic stability.

Area of Science:

  • Cellular biology
  • Molecular genetics
  • DNA repair mechanisms

Background:

  • The Rad9/Rad1/Hus1 complex acts as a crucial sensor for DNA damage and replication stress.
  • This sliding-clamp complex is essential for initiating cell cycle checkpoint signaling.

Purpose of the Study:

  • To investigate the role of Rad1 within the Rad9/Rad1/Hus1 complex in DNA replication and checkpoint control.
  • To determine the consequences of Rad1 loss on cellular proliferation and genomic integrity in mammalian cells.

Main Methods:

  • Depletion of Rad1 in mammalian cells using specific techniques.
  • Analysis of checkpoint signaling pathways, including ATR-dependent Chk1 and ATM-dependent Chk2 activation.
  • Assessment of DNA replication progression, S-phase control, and chromosomal stability.

Main Results:

  • RAD1 is essential for sustained cell proliferation; its loss destabilizes the Rad9/Rad1/Hus1 complex.
  • Rad1 depletion impairs ATR-dependent Chk1 activation but not ATM-dependent Chk2 activation.
  • Loss of Rad1 leads to defects in S-phase control, compromised DNA damage-induced arrest (RDS phenotype), and impaired replication recovery.
  • Rad1-deficient cells exhibit chromosomal abnormalities, suggesting a role in maintaining genomic integrity.

Conclusions:

  • The Rad9/Rad1/Hus1 complex, particularly Rad1, is critical for ATR-dependent checkpoint signaling.
  • Rad1 plays a key role in facilitating DNA replication and maintaining genomic integrity.
  • Disruption of the Rad9/Rad1/Hus1 complex compromises cellular responses to DNA damage and replication stress.

More Related Videos

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

Visualizing and Quantifying Endonuclease-Based Site-Specific DNA Damage

Published on: August 21, 2021

Detection of Homologous Recombination Intermediates via Proximity Ligation and Quantitative PCR in Saccharomyces cerevisiae07:55

Detection of Homologous Recombination Intermediates via Proximity Ligation and Quantitative PCR in Saccharomyces cerevisiae

Published on: September 11, 2022

Related Concept Videos

The DNA Replication Fork01:02

The DNA Replication Fork

An organism’s genome needs to be duplicated in an efficient and error-free manner for its growth and survival. The replication fork is a Y-shaped active region where two strands of DNA are separated and replicated continuously. The coupling of DNA unzipping and complementary strand synthesis is a characteristic feature of a replication fork.   Organisms with small circular DNA, such as E. coli, often have a single origin of replication; therefore, they have only two replication forks, one in...
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...
Homologous Recombination02:31

Homologous Recombination

The basic reaction of homologous recombination (HR) involves two chromatids that contain DNA sequences sharing a significant stretch of identity. One of these sequences uses a strand from another as a template to synthesize DNA in an enzyme-catalyzed reaction. The final product is a novel amalgamation of the two substrates. To ensure an accurate recombination of sequences, HR is restricted to the S and G2 phases of the cell cycle. At these stages, the DNA has been replicated already and the...
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...
The Spindle Assembly Checkpoint02:19

The Spindle Assembly Checkpoint

The spindle assembly checkpoint is a molecular surveillance mechanism ensuring the fidelity of chromosome segregation during anaphase. The checkpoint monitors the completion of all the prerequisite steps before chromosome segregation to determine whether the segregation process should proceed or be delayed.
Many proteins function together to control the spindle assembly checkpoint. Mutations affecting these proteins may allow cells to proceed into anaphase prematurely, resulting in the...
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...