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RanGTP aids anaphase entry through Ubr5-mediated protein turnover
Hao Jiang1, Xiaonan He2, Di Feng2
1State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, China Department of Embryology, Carnegie Institution for Science, Baltimore, MD 21218.
The Journal of Cell Biology
|October 7, 2015
Summary
RanGTP promotes the breakdown of BuGZ and Bub3 proteins during metaphase, aiding the cell cycle
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- The spindle assembly checkpoint (SAC) ensures accurate chromosome segregation during cell division.
- RanGTP is implicated in SAC regulation, but its precise molecular role remains elusive.
- BuGZ protein stabilizes Bub3, a key SAC component, facilitating its mitotic functions.
Purpose of the Study:
- To elucidate the molecular mechanism by which RanGTP regulates the spindle assembly checkpoint.
- To investigate the role of BuGZ and Bub3 turnover in metaphase-to-anaphase transition.
- To identify the proteins involved in RanGTP-mediated regulation of SAC components.
Main Methods:
- Co-immunoprecipitation assays to study protein interactions.
- Ubiquitination assays to assess protein modification.
- Western blotting to analyze protein levels and turnover.
- Cell cycle analysis to monitor progression through mitosis.
Main Results:
- RanGTP promotes the turnover of BuGZ and Bub3 proteins during metaphase.
- BuGZ and Bub3 interact with both importin-β and the E3 ubiquitin ligase Ubr5.
- RanGTP facilitates the dissociation of importin-β from BuGZ and Bub3, promoting their binding to Ubr5.
- Ubr5-mediated ubiquitination leads to the degradation of BuGZ and Bub3.
Conclusions:
- RanGTP-mediated turnover of BuGZ and Bub3 is crucial for timely metaphase-to-anaphase transition.
- The Ubr5 ubiquitin ligase acts as a key mediator in this process.
- This mechanism links chromosome alignment to SAC silencing, ensuring proper cell division.
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