Vimentin fibers orient traction stress

• Published in: Proceedings of the National Academy of Sciences - PNAS 2017-05, Vol.114 (20), p.5195-5200
• Main Authors: Costigliola, Nancy, Ding, Liya, Burckhardt, Christoph J., Han, Sangyoon J., Gutierrez, Edgar, Mota, Andressa, Groisman, Alex, Mitchison, Timothy J., Danuser, Gaudenz
• Format: Article
• Language: English
• Subjects: Actin; Actins - chemistry; Alignment; Animals; Anisotropy; Architecture; Biological Sciences; Bundles; Bundling; Cell adhesion & migration; Cell migration; Cell Movement - physiology; Cell Polarity - physiology; Control; Correlation; Correlation analysis; Dendritic branching; Editing; Elasticity; Epithelial-Mesenchymal Transition - physiology; Fibers; Fibroblasts; Fibroblasts - chemistry; Filtration; Flow rates; Fragmentation; Fragments; Genomes; Graph matching; Homogenization; Humans; Image analysis; Image processing; Intermediate Filaments - chemistry; Intermediate Filaments - physiology; Mechanical Phenomena; Mechanical stimuli; Mesenchyme; Microtubules; Microtubules - chemistry; Orientation; Spatial analysis; Stress Fibers - chemistry; Stress Fibers - physiology; Stresses; Substrates; Traction; Vimentin; Vimentin - chemistry; Vimentin - metabolism; Vimentin - physiology; Weight-Bearing
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1614610114

The intermediate filament vimentin is required for cells to transition from the epithelial state to the mesenchymal state and migrate as single cells; however, little is known about the specific role of vimentin in the regulation of mesenchymal migration. Vimentin is known to have a significantly greater ability to resist stress without breaking in vitro compared with actin or microtubules, and also to increase cell elasticity in vivo. Therefore, we hypothesized that the presence of vimentin could support the anisotropic mechanical strain of single-cell migration. To study this, we fluorescently labeled vimentin with an mEmerald tag using TALEN genome editing. We observed vimentin architecture in migrating human foreskin fibroblasts and found that network organization varied from long, linear bundles, or “fibers,” to shorter fragments with a mesh-like organization. We developed image analysis tools employing steerable filtering and iterative graph matching to characterize the fibers embedded in the surrounding mesh. Vimentin fibers were aligned with fibroblast branching and migration direction. The presence of the vimentin network was correlated with 10-fold slower local actin retrograde flow rates, as well as spatial homogenization of actin-based forces transmitted to the substrate. Vimentin fibers coaligned with and were required for the anisotropic orientation of traction stresses. These results indicate that the vimentin network acts as a load-bearing superstructure capable of integrating and reorienting actin-based forces. We propose that vimentin’s role in cell motility is to govern the alignment of traction stresses that permit single-cell migration.