RhoB Mediates Phosphoantigen Recognition by Vγ9Vδ2 T Cell Receptor

Human Vγ9Vδ2 T cells respond to tumor cells by sensing elevated levels of phosphorylated intermediates of the dysregulated mevalonate pathway, which is translated into activating signals by the ubiquitously expressed butyrophilin A1 (BTN3A1) through yet unknown mechanisms. Here, we developed an unbiased, genome-wide screening method that identified RhoB as a critical mediator of Vγ9Vδ2 TCR activation in tumor cells. Our results show that Vγ9Vδ2 TCR activation is modulated by the GTPase activity of RhoB and its redistribution to BTN3A1. This is associated with cytoskeletal changes that directly stabilize BTN3A1 in the membrane, and the subsequent dissociation of RhoB from BTN3A1. Furthermore, phosphoantigen accumulation induces a conformational change in BTN3A1, rendering its extracellular domains recognizable by Vγ9Vδ2 TCRs. These complementary events provide further evidence for inside-out signaling as an essential step in the recognition of tumor cells by a Vγ9Vδ2 TCR. [Display omitted] •Identification of SNPs near RhoB is associated with poor Vγ9Vδ2 T cell activation•RhoB activity and distribution in tumor cells modulate Vγ9Vδ2 T cell activation•Relocalization of RhoB induces membrane immobility of BTN3A1•Tumor recognition by a Vγ9Vδ2 TCR depends on BTN3A1 conformation Sebestyen et al. show that Vγ9Vδ2TCR activation is modulated by the GTPase activity of RhoB in tumor cells, and by the relocalization of RhoB to BTN3A1. Subsequently, a phosphoantigen-induced conformational change in BTN3A1 leads to its recognition by Vγ9Vδ2TCRs.