Light-sensitive G protein-coupled receptors (GPCRs) such as opsins have been employed to activate some G protein pathways signaling with subcellular spatial control. However, a limitation has been the lack of approaches to selectively control heterotrimeric G protein subunit signaling downstream of GPCRs with a user-defined spatial and temporal control. For example, GNAQ is a cancer driver gene and encodes G protein alpha q (Gaq). Phospholipase C beta (PLC b) is a major downstream effector of Gaq that hydrolyze phosphatidylinositol-4, 5-bisphosphate (PIP2), generating inositol-1, 4, 5-triphosphate (IP3) and diacylglycerol (DAG). The subsequent signaling controls a wide array of physiological functions, including muscle contraction, opioid-induced pain sensitivity, cell proliferation, and survival, and thus underlies many diseases such as heart diseases, cancer, and diabetes. To examine Gbg-independent regulation of Gaq signaling, we engineered a series of highly efficient optogenetic inhibitors of GaqGTP signaling that provides precise subcellular-special and millisecond-temporal control. Using these capabilities, we have uncovered several novel regulatory mechanisms in Gq-pathway-governed directional cell migration.
