Spatial Encoding of Translational Regulation by GPCRs

Abstract

G protein-coupled receptors (GPCRs) are the largest class of membrane proteins and are ubiquitously expressed to play key roles in nearly every cell in the human body. Ligand activation of GPCRs induces a plethora of cellular responses that ultimately culminate in changes in protein expression. Control of gene expression by GPCRs has been studied almost exclusively at the transcriptional level, neglecting an extensive amount of regulation that takes place translationally. Hence, little is known about the nature and mechanisms of gene-specific post-transcriptional regulation downstream of receptor activation. Here, we apply an unbiased multiomics approach to delineate an extensive translational regulatory program initiated by the prototypical beta2-adrenergic receptor (β2-AR) and provide mechanistic insights into how these processes are orchestrated. Using ribosome profiling (Ribo-seq), we identify nearly 120 novel gene targets of adrenergic receptor activity for which expression is exclusively regulated at the level of translation. We next show that all translational changes are induced selectively by endosomal β2-ARs. In mechanistic investigations, we report that β2-AR crosstalk with the mTOR pathway and iron regulatory pathways drives translation or select transcripts. Site-selective crosstalk between the β2-AR and mTOR pathways is observed in cardiomyocytes and neurons, across a range of endogenous and synthetic adrenergic agonists, and for other GPCRs with intracellular activity. Together, this comprehensive analysis of drug-induced translational regulation establishes a critical role for location-biased GPCR signaling in fine-tuning the cellular protein landscape.