T-Cell Signaling Microcluster Transport Toward the Synaptic Center is Influenced by Membrane Ligand Mobility

Abstract

The engagement of the T cell antigen receptor (TCR) by antigens induces dynamic molecular reorganization and leads to the recruitment to the plasma membrane of many critical effectors, including zeta-chain associated protein kinase of 70kDa (ZAP70) and adaptor SH2 domain containing leukocyte phosphoprotein of 76kDa (SLP76). Live-cell tracking experiments have revealed the dynamic segregation of these signaling molecules and the formation of immunological synaptic (IS) at the cell-cell interface. However, the correlation between microcluster movement and membrane ligand mobility has remained unclear. Studies so far have focused on either extremely mobile ligands on single-component bilayer surfaces or completely immobile stimuli on glass coverslips. We prepared a supported lipid bilayer system composed of a binary mixture of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) that allows us to vary ligand mobility by adjusting the mixing ratio of phospholipids. Biotinylated anti-human CD3 antibodies are adsorbed via neutravidin to supported lipid bilayers containing polyethylene glycol biotinylated lipids. Human Jurkat T cells are thus activated by our stimulatory bilayer and we track microclusters via fluorescence imaging. We found that ZAP70 microclusters exhibit faster tracking velocity and longer trajectory length in response to increasingly mobile ligands. In contrast, SLP76 microclusters are less responsive to varied ligand mobility. Our measurements of the radial microcluster velocity suggests both ZAP70 and SLP76 microclusters exhibit acceleration toward the center of the cell. Our measurements may help understand the physiological relevance of T-cell synapse dynamics. Correction et al.Biophysical JournalMay 04, 2011In Brief3239-Pos. Full-Text PDF Open Archive