Insights into the Micromechanical Properties of the Metaphase Spindle

SummaryThe microtubule-based metaphase spindle is subjected to forces that act in diverse orientations and over a wide range of timescales. Currently, we cannot explain how this dynamic structure generates and responds to forces while maintaining overall stability, as we have a poor understanding of its micromechanical properties. Here, we combine the use of force-calibrated needles, high-resolution microscopy, and biochemical perturbations to analyze the vertebrate metaphase spindle's timescale- and orientation-dependent viscoelastic properties. We find that spindle viscosity depends on microtubule crosslinking and density. Spindle elasticity can be linked to kinetochore and nonkinetochore microtubule rigidity, and also to spindle pole organization by kinesin-5 and dynein. These data suggest a quantitative model for the micromechanics of this cytoskeletal architecture and provide insight into how structural and functional stability is maintained in the face of forces, such as those that control spindle size and position, and can result from deformations associated with chromosome movement.PaperFlick To view the video inline, enable JavaScript on your browser. However, you can download and view the video by clicking on the icon belowHelp with MP4 filesOptionsDownload video (11573 K)

Graphical AbstractFigure optionsDownload full-size imageDownload high-quality image (334 K)Download as PowerPoint slideHighlights► Spindle's viscoelastic properties vary with timescale and direction of applied force ► Kinetochore and nonkinetochore microtubule bending contribute to spindle elasticity ► Spindle viscosity depends on microtubule crosslinking dynamics ► The metaphase spindle is most viscous at the timescale of typical chromosome motion