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Gαs is dispensable for β-arrestin coupling but dictates GRK selectivity and is predominant for gene expression regulation by β2-adrenergic receptor.

β-arrestins play a key role in G protein-coupled receptor (GPCR) internalization, trafficking, and signaling. Whether β-arrestins act independently of G protein-mediated signaling has not been fully elucidated. Recent studies using genome editing approaches revealed that whereas G proteins are essential for ERK activation by GPCRs, β-arrestins play a more prominent role in signal compartmentalization. However, in the absence of G proteins, GPCRs may not be able to activate β-arrestins, thereby limiting the ability to distinguish G protein from β-arrestin-mediated signaling events. We used β2-adrenergic receptor (β2AR) and its β2AR-C tail mutant expressed in HEK293 cells wild type or CRISPR/Cas9 gene edited for Gαs, β-arrestin1/2, or GPCR kinases (GRK) 2/3/5/6 in combination with arrestin conformational sensors to elucidate the interplay between Gαs and β-arrestins in signaling to the nucleus, thereby controlling gene expression. We found that Gαs is not required for β2AR and β-arrestin conformational changes, β-arrestin recruitment, and receptor internalization, but that Gαs dictates the GRKs isoforms involved in β-arrestin recruitment. By RNAseq analysis we found that PKA and MAPK gene signatures were activated by stimulation of β2AR in wild type and β-arrestin1/2-KO cells but absent in Gαs-KO cells. These results were validated by rescue experiments expressing Gαs in the corresponding KO cells and silencing β-arrestins in wild type cells. These findings were extended to cellular systems expressing endogenous levels of β2AR. Overall, our results support that Gs is essential for β2AR-promoted PKA and MAPK gene expression signatures, while β-arrestins initiates signaling events modulating Gαs-driven nuclear transcriptional activity.

Date de publication
27 septembre 2023
Burghi V, Paradis JS, Officer A, Adame Garcia S, Wu X, Matthees ES, Barsi-Rhyne B, Ramms DJ, Clubb L, Acosta M, Tamayo P, Bouvier M, Inoue A, von Zastrow M, Hoffmann C, Gutkind JS
Référence PubMed
J Biol Chem 2023:105293
ID PubMed
Moores Cancer Center, University of California San Diego, La Jolla, California, USA; Department of Pharmacology, University of California San Diego, La Jolla, California, USA.