14-3-3 Proteins are Negative Regulators of β2 Adrenergic Receptor Function

Abstract ID 95038 Poster Board 353 Physiological responses to catecholamines in many organs, such as the heart, airways, and pancreas, rely on accurate signaling through the beta 2 adrenergic receptor (B2AR), a prototypical G protein-coupled receptor. It is becoming increasingly clear that a complete B2AR physiological response is integrated from many discrete receptor signaling events, separated in time, that originate from different subcellular locations in cells. The spatiotemporal fidelity of these discrete signaling events relies on two critical processes–those that localize receptors to specific compartments, and those that ensure that the receptors couple to the correct signaling components in these compartments. The biochemical networks that mediate these processes, however, are still not fully understood. In this study, we focused on endosomal compartments to identify novel protein-protein interactions that ensure B2AR localization and signaling on endosomes. Using unbiased APEX proximity labeling to capture transient interactions of B2AR during endosomal localization, we identified 14-3-3 proteins–a physiologically relevant family of phosphopeptide binding proteins–as novel regulators of B2AR function. Multiple 14-3-3 protein isoforms preferentially associated with B2AR in an agonist-dependent manner. 14-3-3 proteins acted as negative regulators of both global cAMP production and arrestin recruitment downstream of B2AR activation, without affecting ERK activation or receptor trafficking kinetics. Our results identify 14-3-3 proteins as important regulators of B2AR signaling, and suggest that B2AR interacts with discrete and regulated protein complexes at different subcellular sites to ensure spatiotemporal fidelity in signaling.