Aurora kinase promotes turnover of kinetochore microtubules to reduce chromosome segregation errors

Area of Science:

• Cell Biology
• Molecular Biology
• Genetics

Background:

• Merotelic kinetochore orientation is a common mitotic error where kinetochores attach to microtubules from both spindle poles.
• This misattachment can lead to anaphase lagging chromosomes and aneuploidy, yet it often evades detection by the spindle assembly checkpoint.
• While typically corrected before anaphase, the precise mechanisms of merotelic attachment correction remain incompletely understood.

Purpose of the Study:

• To investigate the role of Aurora kinase activity in the correction of merotelic kinetochore attachments during mitosis.
• To determine the effect of partial Aurora kinase inhibition on chromosome segregation fidelity and kinetochore-microtubule dynamics.

Main Methods:

• Utilized PtK1 cells treated with ZM447439, a partial inhibitor of Aurora kinase activity, at a specific concentration (3 microM).
• Assessed the frequency of merotelic kinetochores and lagging chromosomes in anaphase.
• Measured kinetochore-microtubule turnover dynamics using fluorescence dissipation after photoactivation experiments.

Main Results:

• Partial Aurora kinase inhibition significantly increased the frequency of merotelic kinetochores and lagging chromosomes without affecting overall chromosome alignment or histone phosphorylation.
• Inhibition suppressed kinetochore-microtubule turnover in prometaphase, suggesting a role in attachment stabilization.
• The findings indicate that Aurora kinase activity is crucial for the preanaphase correction of merotelic attachments.

Conclusions:

• Aurora kinase activity is essential for a preanaphase correction mechanism that resolves merotelic kinetochore attachments.
• Partial inhibition of Aurora kinase disrupts this correction process, leading to increased aneuploidy.
• Understanding this mechanism provides insights into maintaining chromosomal stability during cell division.