Role of vimentin intermediate filament networks and cytoskeletal crosstalk in T cell activation

T cells assist with initiating an adaptive immune response to specific pathogens. Upon activation, T cells undergo dramatic cytoskeletal rearrangements that drive centrosome polarization, force generation, and activation of signaling pathways that promote immune function. While functions of the actin and microtubule (MT) cytoskeletons during T cell activation are well-studied, the role of intermediate filaments (IFs) is less clear. We examined the role of vimentin IFs – known to regulate forces and cytoskeletal crosstalk in other cells – during activation in a Jurkat T cell model. We observed that the vimentin network contracts at the immune synapse (IS) upon activation; this contraction is coordinated with centrosome polarization and requires the MT motor dynein but is independent of myosin. Super-resolution imaging revealed that vimentin and MTs appear to form complementary networks in activated cells. To further investigate cytoskeletal crosstalk during activation, we studied effects of vimentin knockdown at the IS. TIRF microscopy revealed altered MT dynamics, while actin flows were unaffected. Since dynamic MTs have been shown to regulate traction forces during activation, we used Traction Force Microscopy to measure force exertion by vimentin knockdown cells. Finally, we studied how vimentin depletion affects early signaling at the IS. Our results suggest a role for vimentin in cytoskeletal crosstalk and signaling during T cell activation.