Vimentin Intermediate Filaments Stabilize Dynamic Microtubules by Direct Interactions

Many cellular functions such as mitosis, mechanics and intracellular transport rely on the organization and interaction of actin filaments, microtubules (MTs) and intermediate filaments (IFs), which are the main constituents of the eukaryotic cytoskeleton. Here, we study the interaction between vimentin IFs and MTs in a minimal in vitro system and show that MTs are stabilized against depolymerization by the IFs. To explore the nature of this interaction and probe for electrostatic and hydrophobic contributions, we directly measure forces between individual MTs and vimentin IFs using optical tweezers in different buffer conditions. Theoretical modeling results in the corresponding energy landscape. Feeding back the physical parameters describing the interaction into a Monte Carlo simulation that mimicks dynamic MTs indeed confirms that the additional interaction with IFs stabilizes MTs. We suggest that within cells, the interactions we observe might be a mechanism for cells to fine-tune cytoskeletal crosstalk and MT stability.
doi.org/10.1101/2020.05.20.106179