  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.
