Inferring the Forces Controlling Metaphase Kinetochore Oscillations by Reverse Engineering System Dynamics.

Area of Science:

• Cell Biology
• Biophysics
• Mechanobiology

Background:

• Kinetochores link sister chromatids to spindle microtubules, crucial for chromosome segregation.
• Existing methods lack systematic force measurement on kinetochores in living cells.
• Chromosome movement relies on kinetochore-fiber forces, polar ejection forces (PEF), and chromatin elasticity.

Purpose of the Study:

• To develop and validate a computational method for estimating forces acting on kinetochores in vivo.
• To quantify the relative contributions of different force components during chromosome dynamics.
• To analyze force profiles during directional switches in human cells.

Main Methods:

• Development of mathematical models for reverse engineering kinetochore tracking data.
• Application of models to high-resolution kinetochore pair trajectories from human cells.
• Indirect computation of relative force components (K-fibre, spring force, PEF) using estimated model parameters.

Main Results:

• Identified distinct temporal force profiles during directional switches of sister kinetochores.
• Kinetochore-fiber (K-fibre) force identified as the dominant force during oscillations.
• Centromeric spring force found to be the smallest but possess the strongest directional switching signature.
• Observed structural organization of the metaphase plate influencing PEF and oscillation amplitude.

Conclusions:

• The data-driven reverse engineering approach enables robust testing of mathematical models for kinetochore dynamics.
• This methodology provides a foundation for future studies on protein contributions to kinetochore force generation and sensing.
• The findings offer new insights into the mechanical regulation of chromosome segregation.