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Updated: Jul 28, 2026
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Live Cell Imaging to Assess the Dynamics of Metaphase Timing and Cell Fate Following Mitotic Spindle Perturbations
Published on: September 20, 2019
A new view of the spindle checkpoint
1Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA. hoyt@jhu.edu
The Journal of Cell Biology
|September 6, 2001
Summary
The spindle checkpoint prevents cell division errors. New research shows BubR1, not Mad2, is the key protein inhibiting the anaphase-promoting complex (APC) to halt cell cycle progression.
Area of Science:
- Cell Biology
- Molecular Biology
- Genetics
Background:
- The spindle checkpoint ensures accurate chromosome segregation during cell division.
- Previous models identified Mad2 as the primary inhibitor of the anaphase-promoting complex (APC).
Purpose of the Study:
- To re-evaluate the role of Mad2 and BubR1 in inhibiting APC function during the spindle checkpoint.
- To identify the principal APC inhibitor within the spindle checkpoint pathway.
Main Methods:
- Comparative analysis of Mad2 and BubR1 protein functions.
- In vitro assays measuring APC ubiquitin ligase activity.
- Cell-based assays assessing cell cycle progression.
Main Results:
- BubR1 demonstrates significantly higher inhibitory potency against APC compared to Mad2.
- Mad2's inhibitory effect on APC is considerably weaker than previously assumed.
- BubR1 is identified as a more critical regulator of APC activity in the spindle checkpoint.
Conclusions:
- BubR1, rather than Mad2, is the predominant inhibitor of APC in the spindle checkpoint.
- This finding necessitates a revision of the current understanding of spindle checkpoint mechanisms.
- BubR1's potent APC inhibition highlights its crucial role in preventing aneuploidy.
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The bipolar configuration of the mitotic spindle facilitates chromosomal segregation, preparing the cell for division. One mechanism that ensures bipolar mitotic...
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