Characterizing the role of vimentin intermediate filament networks in mediating cytoskeletal cross-talk during T cell activation

T cells play a key role in adaptive immunity, initiating a tailored immune response to specific pathogens. Upon activation, T cells undergo dramatic cytoskeletal rearrangements that drive polarization, force generation at the cell-substrate interface (immune synapse), and activation of signaling pathways that promote immune function. While functions of the actin and microtubule (MT) cytoskeletons during activation have been well-studied, the role of intermediate filaments (IFs) is less understood. We examined the role of vimentin IFs in mediating cytoskeletal crosstalk during T cell activation. Using confocal microscopy, we observed that vimentin contracts at the immune synapse upon activation, and that this contraction is regulated by dynein activity and coordinated with centrosome polarization. We additionally used TIRF microscopy to study MT dynamics in activated control and vimentin knock-down Jurkat T cells, revealing higher MT growth speeds in vimentin-depleted cells. Since dynamic MTs have been shown to regulate traction forces during activation, we then used TFM to compare force generation by control and vimentin knock-down cells. Finally, using polyacrylamide gels of tunable stiffness, we examined whether vimentin is required for centrosome polarization and synaptic actin accumulation in response to stiffness. Our results suggest that vimentin mediates cytoskeletal crosstalk during T cell activation, raising questions about the underlying molecular mechanisms.