Kinesin-8 effects on mitotic microtubule dynamics contribute to spindle function in fission yeast

TL;DR

This study investigates how kinesin-8 proteins Klp5 and Klp6 influence microtubule dynamics, spindle stability, and chromosome movements during mitosis in fission yeast, revealing their critical roles in proper cell division.

Contribution

It provides new insights into the specific roles of kinesin-8 proteins in mitotic spindle regulation and chromosome segregation, highlighting differences between Klp5 and Klp6 functions.

Findings

Klp5 deletion causes abnormal kinetochore pushing and tripolar spindles.

Kinesin-8 deletion leads to spindle length fluctuations.

Microtubule dynamics disruption explains chromosome movement defects.

Abstract

Kinesin-8 motor proteins destabilize microtubules. Their absence during cell division is associated with disorganized mitotic chromosome movements and chromosome loss. Despite recent work studying effects of kinesin 8s on microtubule dynamics, it remains unclear whether the kinesin-8 mitotic phenotypes are consequences of their effect on microtubule dynamics, their well-established motor activity, or additional unknown functions. To better understand the role of kinesin-8 proteins in mitosis, we have studied the effects of deletion of the fission-yeast kinesin-8 proteins Klp5 and Klp6 on chromosome movements and spindle length dynamics. Aberrant microtubule-driven kinetochore pushing movements and tripolar mitotic spindles occurred in cells lacking Klp5 but not Klp6. Kinesin-8 deletion strains showed large fluctuations in metaphase spindle length, suggesting a disruption of spindle length stabilization. Comparison of our results from light microscopy with a mathematical model suggests that kinesin-8 induced effects on microtubule dynamics, kinetochore attachment stability, and sliding force in the spindle can explain the aberrant chromosome movements and spindle length fluctuations seen.