However, such

mutant cells are unable to display activation-dependent TCR clustering, IS formation, expression of CD25/CD69 activation markers, or produce/secrete cytokine, effects also seen in the corresponding APCs. We are the first to show a direct TCR-actin linkage, providing Selleck EPZ-6438 the missing gap linking between TCR-mediated Ag recognition, specific cytoskeleton orientation toward the T-cell–APC interacting pole and long-lived IS maintenance. Upon TCR-mediated Ag-MHC recognition, polarized reorganization of TCRs together with additional cell surface receptors and intracellular signaling molecules is initiated toward the T-cell–antigen-presenting cell (APC) interface, segregating into receptor

microclusters and eventually to a defined immune synapse (IS) [1-3]. The exact mechanism that controls the dynamics TCR rearrangement in the IS is as yet unknown. However, it is well established that TCR-mediated signaling controls synapse formation, since disruption of TCR signaling molecules such as LCK and VAV prevents this process [4, 5]. In addition, many studies have indicated that polymerization and remodeling of the actin-based cytoskeleton creates a scaffold critical to IS formation and stabilization [6]. Actin reorganization at the IS also plays a role in advanced stages of activation, enabling directed secretion of cytokines and execution of PD184352 (CI-1040) T-cell effector functions NVP-LDE225 price [7]. Disruption of the actin-based cytoskeleton or deficiency in key actin-regulatory proteins causes severe alterations of TCR-mediated activation progression [7]. Various studies including ours demonstrated that ∼30% of the total TCRs are found in the detergent-insoluble cell fraction (dicf)-TCRs and were suggested as being linked

to actin-based cytoskeleton via ζ. dicf-TCRs were shown to be expressed on the cell surface of both nonactivated and activated T cells [8, 9]. Although the unique features of dicf-TCRs, such as conformation and phosphorylation pattern [10] suggest a distinct role in T-cell function compared with that of detergent-soluble cell fraction (dscf)-TCRs, the mode of association with the cytoskeleton and their functional significance remain unclear. It was previously published that upon TCR-mediated activation, although the majority of the receptors are internalized and degraded within 1–4 h, T-cell–APC interactions and TCR-mediated signaling are still evident for up to 10 h, and cytokine secretion persists for even longer (10–24 h) [11].