Vimentin intermediate filaments: the origin of stretchability and their direct interaction with actin filaments

ongoing

Many cellular processes, such as cell shape, mechanics, and intracellular transport, rely on the organization of and interactions between cytoskeletal filaments (CFs). Intermediate filaments (IFs) are the least studied CFs, with little knowledge of their interactions with other CFs, particularly actin filaments (AFs). Vimentin, one of the most abundant members of the IF family, is upregulated during epithelial-to-mesenchymal transition and in epithelial cancers, its expression is associated with poor prognosis. Their hierarchical structure gives them great stretchability, which aids cells under large deformations. However, little is known about the deformation-induced unfolding of alpha helices and the parameters that drive it. This study focuses on understanding the origin of vimentin IF (VIF) stretchability by providing direct visualization of the unfolding of alpha helices within the VIFs and transition to beta sheets upon stretching under various conditions. Interactions of VIFs with AFs play an important role in cell mechanics and successful mitosis. Yet, if these filaments interact directly is still a matter of debate. The proposed project focuses on the interaction between VIFs and AFs to determine whether they interact directly at the filament level and, if so, what are the strengths of the interactions and their binding/unbinding rates. A combination of approaches and methodologies will be used, including in vitro reconstituted filaments, optical tweezers, tip-enhanced Raman spectroscopy, computer simulation. The knowledge gained from this project will help understand crucial physiological and pathological processes. The host and supervisor are well-equipped for this project, with the supervisor's expertise in understanding IF mechanics and function as well as interaction between CFs utilizing a multiscale biophysical approach. The PF will establish a unique niche in biophysics research and a robust CV for future grant applications and research positions.