Related Experiment Video
Updated: Sep 4, 2025

Two- and Three-Dimensional Live Cell Imaging of DNA Damage Response Proteins
Published on: September 28, 2012
The CIP2A-TOPBP1 complex safeguards chromosomal stability during mitosis
Mara De Marco Zompit1, Mònica Torres Esteban1, Clémence Mooser1
1Department of Gynecology, University of Zurich and University Hospital Zurich, Schlieren, Switzerland.
Cancer cells utilize a novel protein complex, CIP2A-TOPBP1, to manage DNA double-strand breaks (DSBs) during mitosis, ensuring genome stability. This discovery offers new insights into cancer cell repair mechanisms and potential therapeutic targets.
Area of Science:
- Molecular Biology
- Cell Cycle Regulation
- DNA Repair Mechanisms
Background:
- Accurate repair of DNA double-strand breaks (DSBs) is vital for maintaining genome integrity.
- Mitosis involves inactivating DSB repair in favor of chromosome stabilization.
- The adaptor protein TOPBP1 is implicated in this mitotic process, but its mechanism is unclear.
Purpose of the Study:
- To elucidate the mechanism by which DNA double-strand break repair is regulated during mitosis.
- To identify key proteins involved in stabilizing broken chromosomes during cell division.
- To understand the role of TOPBP1 in mitotic genome maintenance.
Main Methods:
- Identified CIP2A as a novel TOPBP1-interacting protein.
- Investigated CIP2A's localization and function during the cell cycle, particularly in mitosis.
- Assessed the impact of CIP2A deficiency on cellular radio-sensitivity, micronuclei formation, and chromosomal instability.
Main Results:
- CIP2A regulates TOPBP1 localization specifically during mitosis.
- Cells lacking CIP2A exhibit increased radio-sensitivity and chromosomal instability.
- CIP2A forms a complex with MDC1 and TOPBP1 on mitotic chromatin, promoting TOPBP1 recruitment to DSBs.
Conclusions:
- CIP2A acts as a crucial regulator of TOPBP1 during mitosis.
- The CIP2A-TOPBP1 complex is essential for genome maintenance in mitosis.
- This study uncovers a novel mitosis-specific genome maintenance complex, CIP2A-TOPBP1.
More Related Videos
05:35Immunofluorescence Analysis of Endogenous and Exogenous Centromere-kinetochore Proteins
Published on: March 3, 2016
08:33Combining Mitotic Cell Synchronization and High Resolution Confocal Microscopy to Study the Role of Multifunctional Cell Cycle Proteins During Mitosis
Published on: December 5, 2017
Related Concept Videos
The Spindle Assembly Checkpoint
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 Cycle
Separation of Sister Chromatids
At the onset of anaphase, separase, a proteolytic enzyme, is...
Anaphase Promoting Complex
Negative Regulator Molecules
Meiosis II
The timing and cell division patterns of meiosis differ between males and females. In male meiosis, the centrosomes are part of the formation of the meiotic spindle. However, in oocytes, including that of humans, Drosophila,...