Optogenetic Clustering and Stimulation of the T Cell Receptor in Nongenetically Modified Human T Cells

Methods for the precise temporal control of cell surface receptor activation are indispensable for the investigation of signaling processes in mammalian cells. Optogenetics enables such precise control, but its application in primary cells is limited by the imperative for genetic manipulation of target cells. We here describe a method that overcomes this obstacle and enables the precise activation of the T cell receptor in nongenetically engineered human T cells by light. Our optogenetic receptor activation system OptoREACT employs a TCR-specific scFv fused to PIF6 that interacts with tetramerized PhyB in a light-dependent manner and thereby clusters and activates the T cell receptor in response to red light. OptoREACT not only omits genetic manipulation of the target cell but, because of its modular nature, is likely applicable to a broad range of oligomerization-activated cell surface receptors.