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Updated: Jul 30, 2025
Directly Measuring Forces Within Reconstituted Active Microtubule Bundles
Published on: May 10, 2022
Robust microtubule dynamics facilitate low-tension kinetochore detachment in metaphase
Sneha Parmar1, Samuel J Gonzalez1, Julia M Heckel1
1Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN, USA.
Abstract:
During mitosis, sister chromatids are stretched apart at their centromeres via their attachment to oppositely oriented kinetochore microtubules. This stretching generates inwardly directed tension across the separated sister centromeres. The cell leverages this tension signal to detect and then correct potential errors in chromosome segregation, via a mechanical tension signaling pathway that detaches improperly attached kinetochores from their microtubules. However, the sequence of events leading up to these detachment events remains unknown. In this study, we used microfluidics to sustain and observe low-tension budding yeast metaphase spindles over multiple hours, allowing us to elucidate the tension history prior to a detachment event. We found that, under conditions in which kinetochore phosphorylation weakens low-tension kinetochore-microtubule connections, the mechanical forces produced via the dynamic growth and shortening of microtubules is required to efficiently facilitate detachment events. Our findings underscore the critical role of robust kinetochore microtubule dynamics in ensuring the fidelity of chromosome segregation during mitosis.
Insights
Mechanical forces from dynamic microtubules, not just phosphorylation, are crucial for detaching improperly attached kinetochores during cell division. This ensures accurate chromosome segregation, vital for mitosis fidelity.
Area of Science:
- Cell Biology
- Biophysics
- Genetics
Background:
- During mitosis, chromosome segregation relies on kinetochore microtubules exerting tension.
- Cellular mechanisms detect and correct errors in chromosome attachment via tension signaling.
- The precise sequence of events preceding kinetochore detachment under low tension remains unclear.
Purpose of the Study:
- To investigate the tension history and molecular events leading to kinetochore-microtubule detachment.
- To elucidate the role of mechanical forces and phosphorylation in correcting chromosome segregation errors.
Main Methods:
- Utilized microfluidics to maintain and observe budding yeast metaphase spindles under sustained low-tension conditions for extended periods.
- Analyzed the interplay between kinetochore phosphorylation, microtubule dynamics, and mechanical forces.
Main Results:
- Demonstrated that while kinetochore phosphorylation weakens low-tension connections, dynamic microtubule growth and shortening are essential for efficient detachment.
- Identified mechanical forces generated by microtubule dynamics as a key factor in facilitating detachment events.
Conclusions:
- Robust kinetochore microtubule dynamics are critical for ensuring accurate chromosome segregation during mitosis.
- The findings highlight a previously uncharacterized requirement for microtubule dynamics in the tension-sensing pathway that corrects segregation errors.
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