Engineered Nectin-4 and CD155 novel cis-dimer proteins significantly enhance the binding of their receptor TIGIT 3056

Abstract Description Understanding immune checkpoint receptor and ligand interactions is crucial for immuno-oncology. Nectin-4 and CD155 are Nectin/Nectin-like family ligands of TIGIT (an inhibitory receptor on lymphocytes), can form homodimers on the cell membrane, and are often overexpressed on tumor cells. Nectin-4 and CD155 are type 1 integral membrane proteins. The ectodomain (ECD) containing 3 Ig-like domains (1 Ig-V followed by 2 Ig-C) is responsible for TIGIT interaction. To better mimic the native dimer conformation and quaternary structure, we designed novel soluble Nectin-4 and CD155 cis-homodimers with the ECD 3 Ig-like domains (ECD-3D) fused to a dimer motif at the C-terminus. These dimeric proteins expressed/purified from HEK293 cells had potent binding to the specific antibodies. Very interestingly, these Nectin-4 and CD155 dimeric proteins dramatically enhanced the binding to their receptor TIGIT by > 10 fold compared to the respective monomer proteins, as measured by ELISA. The Nectin-4 dimer DNA immunization elicited potent antibody responses in mice. AlphaFold 2 predicted that the Nectin-4 ECD-3D dimeric protein structure was well-superimposed with the known ECD-2D crystal structure from the RCSB Protein Data Bank. The findings support that the engineered novel Nectin-4 and CD155 cis-dimer proteins mimic native conformations and can be potentially used as advanced bioactive antigens for immuno-oncology research and anti-tumor drug discovery. Topic Categories Tumor Immunology: Checkpoints, Prevention, and Treatment (TIPT)