Low-intensity vibration does not induce changes in microtubule dynamics in vitro

Abstract

Microtubules (MTs) are cytoskeletal filaments responsible for many vital cellular processes including intracellular organelle organization and enabling the movement of intracellular components. While MTs were shown to respond to low frequency and large mechanical signals like substrate strain, how MTs may respond to a high frequency mechanical signal like low-intensity vibrations (LIV) is unknown. Here we quantified the polymerization dynamics of MTs under an acute 1-day LIV protocol applied at 90 Hz and 0.7 xg, a signal we have shown to be effective for altering F-actin dynamics and nuclear stiffness. LIV treatments were compared against Taxol, a potent regulator of MT acetylation. Using mouse mesenchymal stem cells (MSCs) in vitro, we quantified tubulin polymerization via centrifugal fractionation and western blots as well as alpha-tubulin acetylation via immunostaining. Finally, MT growth dynamics were quantified using machine learning-assisted analysis of live cell fluorescence microscopy of MT plus end binding protein EB1. Our results were not able to detect differences between LIV and control groups while Taxol treatment was effective in all measured outcomes. Our findings indicate that LIV applied at 90 Hz and 0.7 xg does not affect MT dynamics in MSCs, suggesting a higher mechanical threshold of MTs when compared to F-actin cytoskeleton.