Nanomechanical Properties of Vimentin Intermediate Filament

Abstract

Vimentin intermediate filament (IF) is one of the major proteins which built the cytoskeleton network alongside with the microtubule and actin filament. Though it was known that the vimentin IF network plays an important role in the mechanical behaviours of cells, it is surprised that its mechanical behaviours are not fully understood to date. The aim of this paper is to study the nanomechanical properties of vimentin IF using the atomic force spectroscopy (AFM) which allows the manipulation and force spectroscopy of filaments. The vimentin intermediate filaments were attached to the APTES (3-aminopropyltriethoxy) functionalized mica which offered better adhesive force. In the force spectroscopy study, the AFM tip was allowed to clamp filaments and then retraced. The force-displacement curve of the process was obtained for analysis. The curves can be grouped into two major groups – sewtooth and plateau. The appearance of sewtooth was more frequent than the plateau. The sudden force changes (jumps from higher to lower force) in sewtooth and plateau curves were also analyzed. It was shown that the partial ruptures which denoted by the jumps favoured small force (~100 pN) and short range (separation of jumps below 25 nm). This result also demonstrated the probability of different modes of partial IF ruptures.