β-Arrestin-dependent, G Protein-independent ERK1/2 Activation by the β2 Adrenergic Receptor*

By Sudha K. Shenoy, M. Drake, C. D. Nelson, Daniel A. Houtz, Kunhong Xiao, Srinivasan Madabushi, Éric Reiter, R. Premont, Olivier Lichtarge, R. J. Lefkowitz. Journal of Biological Chemistry, 2006

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Physiological effects of β adrenergic receptor (β2AR) stimulation have been classically shown to result from Gs-dependent adenylyl cyclase activation. Here we demonstrate a novel signaling mechanism wherein β-arrestins mediate β2AR signaling to extracellular-signal regulated kinases 1/2 (ERK 1/2) independent of G protein activation. Activation of ERK1/2 by the β2AR expressed in HEK-293 cells was resolved into two components dependent, respectively, on Gs-Gi/protein kinase A (PKA) or β-arrestins. G protein-dependent activity was rapid, peaking within 2-5 min, was quite transient, was blocked by pertussis toxin (Gi inhibitor) and H-89 (PKA inhibitor), and was insensitive to depletion of endogenous β-arrestins by siRNA. β-Arrestin-dependent activation was slower in onset (peak 5-10 min), less robust, but more sustained and showed little decrement over 30 min. It was insensitive to pertussis toxin and H-89 and sensitive to depletion of either β-arrestin1 or -2 by small interfering RNA. In Gs knock-out mouse embryonic fibroblasts, wild-type β2AR recruited β-arrestin2-green fluorescent protein and activated pertussis toxin-insensitive ERK1/2. Furthermore, a novel β2AR mutant (β2ART68F,Y132G,Y219A or β2ARTYY), rationally designed based on Evolutionary Trace analysis, was incapable of G protein activation but could recruit β-arrestins, undergo β-arrestin-dependent internalization, and activate β-arrestin-dependent ERK. Interestingly, overexpression of GRK5 or -6 increased mutant receptor phosphorylation and β-arrestin recruitment, led to the formation of stable receptor-β-arrestin complexes on endosomes, and increased agonist-stimulated phospho-ERK1/2. In contrast, GRK2, membrane translocation of which requires Gβγ release upon G protein activation, was ineffective unless it was constitutively targeted to the plasma membrane by a prenylation signal (CAAX). These findings demonstrate that the β2AR can signal to ERK via a GRK5/6-β-arrestin-dependent pathway, which is independent of G protein coupling.

Subfields: Cellular and Molecular Neuroscience, Molecular Biology

View Paper: https://www.semanticscholar.org/paper/50afc387611a86f9ece29224c6663096b00f902d

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Citations in the corpus

Teaching old receptors new tricks: biasing seven-transmembrane receptors (2010, background): “, and the β 2 -adrenergic receptor mutant β2AR(TYY), which contains mutations of three residues crucial for G protein couplin”
Regulation of CXCR4 signaling. (2007, background): “As has recently been suggested for the angiotensin [108,109], vasopressin [110], and β2-adrenergic receptors [111,112], the coordinated action of these kinases may be necessary for proper receptor regulation by dictating specific interactions through alternative phosphorylation patterns.”
Assembly of a β2‐adrenergic receptor—GluR1 signalling complex for localized cAMP signalling (2010, background): “However, agonist-induced internalization typically reduces surface b2AR by o50%, and in some cases as little as 10% (e.g. Shenoy et al, 2006).”
Molecular Mechanism of β-Arrestin-Biased Agonism at Seven-Transmembrane Receptors (2011, background): “, dual role of the GRK/β-arrestin system in desensitization and signaling, different dynamics of ERK activation by G protein–dependent and β-arrestin-dependent mechanisms, functional specialization of the different GRK subtypes) appear to be conserved across multiple 7TMRs, such as the β2AR (72), V2”