Our project is based on our expertise to study and understand the T cell receptor (TCR) as a macromolecular machine. Using our newest knowledge, we aim to generate a new generation of CARs and to simultaneously obtain further insight into the functioning of the TCR. This will be done by a combination of state-of-the-art engineering technologies, signaling studies and functional assays.
We were the first to show that the TCR is expressed on the surface of T cells not only as individual receptors, but also in a preclustered form (nanoclusters) (Schamel et al, 2005; Wang et al, 2016), Importantly, the TCR nanoclusters are stimulated by lower amounts of antigen than the individual TCRs and thus, the proportion of TCRs that form nanoclusters influences the sensitivity of T cells. Indeed, in collaboration with the partner of Madrid, Hisse Martien van Santen, we found that TCR nanoclustering is dynamically regulated (Kumar et al, 2011), since naïve T cells (less sensitive to antigen) contain small, and effector/memory T cells contain large nanoclusters (more sensitive to antigen).
We also found that the TCR undergoes a conformational change upon antigen binding, and that this structural rearrangement is the trigger for signaling (Gil et al, 2002; Minguet et al, 2007). More recently, we have demonstrated that the TCR is in equilibrium between two conformations, the resting and the active one; and the latter one is stabilized by antigen binding (Swamy et al, 2016; Schamel et al, 2017). Using this knowledge, we have already significantly enhance tumor killing by T cells (Dopfer et al, 2014).
Now, we plan to use our knowledge to engineer novel CARs that would incorporate new domains, in order to enhance their activity. Hence, based on currently used CARs and the expertise of this EN-ACT2ING consortium, we plan to test the effect of nanoclustering and conformational changes in signal initiation of these CARs. The sensitivity of the corresponding cells and their capacity to kill tumor cells will also be studied. Importantly, the CARs will be engineered to improve their signaling capacity and to generate fundamental knowledge on the functioning of the TCR itself.
In addition to the program offered by EN-ACT2ING, the PhD student will be part of a local team to work on novel avenues in cancer immunotherapy. He or she will be carefully supervised by ourselves.
References
Dopfer EP, Hartl FA, Oberg HH, Siegers GM, Yousefi OS, Kock S, Fiala GJ, Garcillan B, Sandstrom A, Alarcon B, Regueiro JR, Kabelitz D, Adams EJ, Minguet S, Wesch D, Fisch P, Schamel WW (2014) The CD3 Conformational Change in the gammadelta T Cell Receptor Is Not Triggered by Antigens but Can Be Enforced to Enhance Tumor Killing. Cell Reports 7: 1704-1715
Gil D, Schamel WW, Montoya M, Sanchez-Madrid F, Alarcon B (2002) Recruitment of Nck by CD3 epsilon reveals a ligand-induced conformational change essential for T cell receptor signaling and synapse formation. Cell 109: 901-912
Kumar R, Ferez M, Swamy M, Arechaga I, Rejas MT, Valpuesta JM, Schamel WW, Alarcon B, van Santen HM (2011) Increased Sensitivity of Antigen-Experienced T Cells through the Enrichment of Oligomeric T Cell Receptor Complexes. Immunity 35: 375-387
Minguet S, Swamy M, Alarcon B, Luescher IF, Schamel WW (2007) Full activation of the T cell receptor requires both clustering and conformational changes at CD3. Immunity 26: 43-54
Schamel WW, Arechaga I, Risueno RM, van Santen HM, Cabezas P, Risco C, Valpuesta JM, Alarcon B (2005) Coexistence of multivalent and monovalent TCRs explains high sensitivity and wide range of response. J Exp Med 202: 493-503
Schamel WW, Alarcon B, Hofer T, Minguet S (2017) The Allostery Model of TCR Regulation. J Immunol, in press
Swamy M, Beck-Garcia K, Beck-Garcia E, Hartl FA, Morath A, Yousefi OS, Dopfer EP, Molnar E, Schulze AK, Blanco R, Borroto A, Martin-Blanco N, Alarcon B, Hofer T, Minguet S, Schamel WW (2016) A Cholesterol-Based Allostery Model of T Cell Receptor Phosphorylation. Immunity 44: 1091-1101
Wang F, Beck-Garcia K, Zorzin C, Schamel WW, Davis MM (2016) Inhibition of T cell receptor signaling by cholesterol sulfate, a naturally occurring derivative of membrane cholesterol. Nat Immunol 17: 844-850