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BRET-based effector membrane translocation assay monitors GPCR-promoted and endocytosis-mediated Gq activation at early endosomes.

Wright SC, Lukasheva V, Le Gouill C, Kobayashi H, Breton B, Mailhot-Larouche S, Blondel-Tepaz E, Antunes Vieira N, Costa-Neto C, Héroux M, Lambert NA, Parreiras-E-Silva LT, Bouvier M

Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, QC, H3T 1J4, Canada.

G protein-coupled receptors (GPCRs) are gatekeepers of cellular homeostasis and the targets of a large proportion of drugs. In addition to their signaling activity at the plasma membrane, it has been proposed that their actions may result from translocation and activation of G proteins at endomembranes-namely endosomes. This could have a significant impact on our understanding of how signals from GPCR-targeting drugs are propagated within the cell. However, little is known about the mechanisms that drive G protein movement and activation in subcellular compartments. Using bioluminescence resonance energy transfer (BRET)-based effector membrane translocation assays, we dissected the mechanisms underlying endosomal Gq trafficking and activity following activation of Gq-coupled receptors, including the angiotensin II type 1, bradykinin B2, oxytocin, thromboxane A2 alpha isoform, and muscarinic acetylcholine M3 receptors. Our data reveal that GPCR-promoted activation of Gq at the plasma membrane induces its translocation to endosomes independently of β-arrestin engagement and receptor endocytosis. In contrast, Gq activity at endosomes was found to rely on both receptor endocytosis-dependent and -independent mechanisms. In addition to shedding light on the molecular processes controlling subcellular Gq signaling, our study provides a set of tools that will be generally applicable to the study of G protein translocation and activation at endosomes and other subcellular organelles, as well as the contribution of signal propagation to drug action.

Proc Natl Acad Sci U S A 2021;118(20).

Pubmed ID: 33990469

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