Mechanical Perturbation of Immunological Synapse and Cortical Actin Flow in T Cells

Abstract

Reorganization of membrane components plays an important role in signal transduction. Patterned hybrid live cell-supported membrane junctions provide spatial controls over the lateral transport of signaling molecules inside the cell. Here, we introduce a new technique which allows us to mechanically manipulate the membrane curvatures at hybrid membrane junctions. We demonstrate that large scale of protein patterns in the T cell immunological synapse can be altered merely by imposing a defined membrane curvature from supporting substrates. Our observation suggests that mechanical perturbations of membrane junctions via geometrical modulations result in decreasing actin velocity as well as remodeling actin retrograde flow. We also explore the effects of membrane diffusion barriers on cytoskeletal regulations and receptor transport processes. Flow-based particle tracking algorithms reveal that actin centripetal retrograde flow directs the inward transport of T cell receptor (TCR) clusters. We find that slower actin flow over confined TCR clusters whereas it stays the same level elsewhere. Actin flow regains its velocity after passing through confined TCR clusters. We demonstrate that the dissipated coupling of TCR clusters and actin network can feedback into a frictional coupling model.