Related Experiment Video

Updated: Jul 8, 2026

Combining Mitotic Cell Synchronization and High Resolution Confocal Microscopy to Study the Role of Multifunctional Cell Cycle Proteins During Mitosis
08:33

Combining Mitotic Cell Synchronization and High Resolution Confocal Microscopy to Study the Role of Multifunctional Cell Cycle Proteins During Mitosis

Published on: December 5, 2017

Defective in mitotic arrest 1/ring finger 8 is a checkpoint protein that antagonizes the human mitotic exit network

Robyn L Tuttle1, John Bothos, Matthew K Summers

  • 1Department of Molecular Biology, University of Geneva, 30 quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland.

Molecular Cancer Research : MCR
|January 4, 2008
PubMed

Insights

Researchers identified RNF8 as the human DMA1, crucial for mitotic arrest via the mitotic exit network (MEN). This discovery reveals a second pathway, alongside MAD2, that maintains cell cycle arrest when cells encounter microtubule poisons.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Genetics

Background:

  • The mitotic exit network (MEN) and septation initiation network (SIN) are conserved pathways regulating cell division.
  • These pathways are crucial for proper cell cycle progression and are implicated in maintaining genomic stability.
  • The ubiquitin ligase defective in mitotic arrest 1 (Dma1p) regulates yeast MEN/SIN pathways during checkpoint activation.

Purpose of the Study:

  • To identify the human orthologue of the yeast Dma1p.
  • To investigate the role of the identified human protein in mitotic arrest.
  • To elucidate the involvement of the mitotic exit network (MEN) in response to microtubule poisons.

Main Methods:

  • Identification of human RNF8 as the Dma1p orthologue.
  • siRNA-mediated depletion of RNF8 and MAD2.
  • Nocodazole treatment to induce mitotic arrest.
  • Localization studies of RNF8 at the midbody.
  • Analysis of mitotic arrest in a MEN-dependent and independent manner.

Main Results:

  • Human RNF8 was identified as the orthologue of yeast Dma1p.
  • RNF8 localizes to the midbody.
  • Depletion of RNF8 by siRNA disrupts mitotic arrest in nocodazole-treated cells, dependent on the MEN.
  • Depletion of MAD2 also disrupts mitotic arrest, but independently of the MEN.

Conclusions:

  • RNF8 plays a critical role in maintaining mitotic arrest through a MEN-dependent pathway.
  • Two distinct pathways, one involving RNF8/MEN and another involving MAD2, contribute to mitotic arrest in response to microtubule poisons.
  • This study reveals a novel mechanism for checkpoint control during cell division.

More Related Videos

Manipulation and Analysis of Cell Cycle-Dependent Processes in Budding Yeast08:13

Manipulation and Analysis of Cell Cycle-Dependent Processes in Budding Yeast

Published on: September 26, 2025

Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay12:26

Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay

Published on: May 3, 2018

Related Concept Videos

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...
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...
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...
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.
Separation of Sister Chromatids02:17

Separation of Sister Chromatids

At the transition from prophase to metaphase, there is a reduction in cohesion along the chromosomal arms, resulting in the resolution of sister chromatids. However, residual cohesin connections remain to hold the sister chromatids together until the transition from metaphase to anaphase. The residual connection prevents any premature separation of sister chromatids, blocking the risks of aneuploidy within the daughter cells.
At the onset of anaphase, separase, a proteolytic enzyme, is...