Optical Control of Cell-Surface and Endomembrane-Exclusive β-Adrenergic Receptor Signaling

Beta-adrenergic receptors ({beta}ARs) are G protein-coupled receptors (GPCRs) that mediate catecholamine-induced stress responses, such as heart rate increase and bronchodilation. In addition to signals from the cell surface, {beta}ARs also broadcast non-canonical signaling activities from the cell interior membranes (endomembranes). Dysregulation of these receptor pathways underlies severe pathological conditions. Excessive {beta}AR stimulation is linked to cardiac hypertrophy, leading to heart failure, while impaired stimulation causes compromised fight or flight stress responses and homeostasis. In addition to plasma membrane {beta}AR, emerging evidence indicates potential pathological implications of deeper endomembrane {beta}ARs, such as inducing cardiomyocyte hypertrophy and apoptosis, underlying heart failure. However, the lack of approaches to control their signaling in subcellular compartments exclusively has impeded linking endomembrane {beta}AR signaling with pathology. Informed by the {beta}1AR-catecholamine interactions, we engineered an efficiently photo-labile, protected hydroxy {beta}1AR pro-ligand (OptoIso) to trigger {beta}AR signaling at the cell surface, as well as exclusive endomembrane regions upon blue light stimulation. Not only does OptoIso undergo blue light deprotection in seconds, but it also efficiently enters cells and allows examination of G protein heterotrimer activation exclusively at endomembranes. In addition to its application in the optical interrogation of {beta}ARs in unmodified cells, given its ability to control deep organelle {beta}AR signaling, OptoIso will be a valuable experimental tool.