Single microtubules and small networks become significantly stiffer on short time-scales upon mechanical stimulation

TL;DR

This study reveals that microtubules and small networks significantly stiffen at high frequencies, acting as filters for mechanical signals, which suggests cells can dynamically regulate mechanotransduction.

Contribution

It demonstrates frequency-dependent stiffening of microtubules and small networks, introducing a new perspective on cellular mechanotransduction pathways.

Findings

Microtubules stiffen above 1-30 Hz transition frequency.

Linear filament pairs act as angle-dependent momentum filters.

Triangular networks stabilize mechanical signals.

Abstract

The transfer of mechanical signals through cells is a complex phenomenon. To uncover a new mechanotransduction pathway, we study the frequency-dependent transport of mechanical stimuli by single microtubules and small networks in a bottom-up approach using optically trapped beads as anchor points. We interconnected microtubules to linear and triangular geometries to perform micro-rheology by defined oscillations of the beads relative to each other. We found a substantial stiffening of single filaments above a characteristic transition frequency of 1-30 Hz depending on the filament's molecular composition. Below this frequency, filament elasticity only depends on its contour and persistence length. Interestingly, this elastic behavior is transferable to small networks, where we found the surprising effect that linear two filament connections act as transistor-like, angle dependent momentum filters, whereas triangular networks act as stabilizing elements. These observations implicate that cells can tune mechanical signals by temporal and spatial filtering stronger and more flexibly than expected.