Related Experiment Video
Updated: Jun 19, 2026
06:39
Live Cell Imaging of Chromosome Segregation During Mitosis
Published on: March 14, 2018
Cep55 stabilization is required for normal execution of cytokinesis
Armando van der Horst1, Jacinta Simmons, Kum Kum Khanna
1Signal Transduction Laboratory, Queensland Institute of Medical Research, Brisbane, QLD, Australia.
Cell Cycle (Georgetown, Tex.)
|October 27, 2009
Summary
The peptidyl-prolyl isomerase Pin1 stabilizes the mitotic phosphoprotein Cep55 during cell division. This stabilization is crucial for proper cytokinesis, as Cep55 levels are critical for cell separation and preventing chromosomal instability.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Cytokinesis is essential for cell division, ensuring proper separation of daughter cells.
- Cep55 is a key mitotic phosphoprotein regulating cytokinesis.
- Pin1 (peptidyl-prolyl isomerase) was previously shown to regulate Cep55 phosphorylation by Plk1.
Purpose of the Study:
- To investigate the role of Pin1 in the post-translational stabilization of Cep55 during mitosis.
- To elucidate the relationship between Pin1, Plk1, and Cep55 stability.
- To determine the functional significance of Cep55 stabilization for cytokinesis.
Main Methods:
- RNA interference (siRNA) to knock down Pin1.
- Analysis of Cep55 stability in wild-type and Pin1 knockout mouse embryonic fibroblasts.
- Site-directed mutagenesis of Pin1 binding sites and Plk1 phosphorylation site on Cep55.
- Overexpression of Plk1.
- Assessment of cytokinesis defects.
Main Results:
- Cep55 undergoes post-translational stabilization during mitosis.
- Pin1 knockdown or knockout leads to Cep55 instability.
- Mutating Pin1 binding sites or the Plk1 phosphorylation site on Cep55 reduces its mitotic stability.
- Overexpression of Plk1 increases Cep55 levels.
- Restoring wild-type Cep55 levels partially rescues cytokinesis defects caused by Cep55 depletion, but phosphorylation mutants show limited rescue.
Conclusions:
- Pin1 stabilizes Cep55 during mitosis, likely by regulating Plk1-mediated phosphorylation.
- Adequate levels of stabilized Cep55 are critical for successful cytokinesis.
- Dysregulation of Cep55 stability contributes to cytokinesis defects, potentially leading to chromosomal instability and tumorigenesis.
Related Concept Videos
02:19The 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...
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...
02:19The 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...
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...
02:17Separation 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...
At the onset of anaphase, separase, a proteolytic enzyme, is...
02:17Separation 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...
At the onset of anaphase, separase, a proteolytic enzyme, is...
02:17Microtubule Instability
Microtubules are hollow cylindrical filaments having a diameter of approximately 25 nm and a length that varies from 200 nm to 25 μm. GTP-bound tubulin subunits form αβ-heterodimers for microtubule assembly. These core building blocks interact longitudinally, polymerizing into protofilaments. The protofilaments then interact with one another through lateral bonding forces to form stable cylindrical microtubules. These cylindrical filaments are dynamic as they undergo repeated assembly and...
02:17Microtubule Instability
Microtubules are hollow cylindrical filaments having a diameter of approximately 25 nm and a length that varies from 200 nm to 25 μm. GTP-bound tubulin subunits form αβ-heterodimers for microtubule assembly. These core building blocks interact longitudinally, polymerizing into protofilaments. The protofilaments then interact with one another through lateral bonding forces to form stable cylindrical microtubules. These cylindrical filaments are dynamic as they undergo repeated assembly and...