Gαs is dispensable for β-arrestin coupling but dictates GRK selectivity and is predominant for gene expression regulation by β2-adrenergic receptor
Valeria Burghi, Justine S. Paradis, Adam Officer, Sendi Rafael Adame-Garcia, Xingyu Wu, Edda S. F. Matthees, Benjamin Barsi‐Rhyne, Dana J. Ramms, Lauren Clubb, Monica Acosta, Pablo Tamayo, Michel Bouvier, Asuka Inoue, Mark von Zastrow, Carsten Hoffmann, J. Silvio Gutkind
Abstract
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. Studies using genome-editing approaches revealed that whereas G proteins are essential for mitogen-activated protein kinase activation by GPCRs., β-arrestins play a more prominent role in signal compartmentalization. However, in the absence of G proteins, GPCRs may not 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 human embryonic kidney 293 cells wildtype or CRISPR–Cas9 gene edited for Gα s , β-arrestin1/2, or GPCR kinases 2/3/5/6 in combination with arrestin conformational sensors to elucidate the interplay between Gα s and β-arrestins in controlling gene expression. We found that Gα s is not required for β2AR and β-arrestin conformational changes, β-arrestin recruitment, and receptor internalization, but that Gα s dictates the GPCR kinase isoforms involved in β-arrestin recruitment. By RNA-Seq analysis, we found that protein kinase A and mitogen-activated protein kinase gene signatures were activated by stimulation of β2AR in wildtype and β-arrestin1/2-KO cells but absent in Gα s -KO cells. These results were validated by re-expressing Gα s in the corresponding KO cells and silencing β-arrestins in wildtype cells. These findings were extended to cellular systems expressing endogenous levels of β2AR. Overall, our results support that Gs is essential for β2AR-promoted protein kinase A and mitogen-activated protein kinase gene expression signatures, whereas β-arrestins initiate signaling events modulating Gα s -driven nuclear transcriptional activity.