Arrestin3 mediates D 2 dopamine receptor internalization

Molecular Neuropharmacology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA.
Synapse (Impact Factor: 2.13). 07/2009; 63(7):621-4. DOI: 10.1002/syn.20636
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Available from: Annika Thorsell, Oct 06, 2015
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    • "The long-term activation of D2R could lead to D2R internalization6. Internalization is important for regulating GPCR downstream signaling. "
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    ABSTRACT: Aim: To explore the effects of heterodimerization of D2 receptor/A2a receptor (D2R/A2aR) on D2R internalization and D2R downstream signaling in primary cultured striatal neurons and HEK293 cells co-expressing A2aR and D2R in vitro. Methods: Primary cultured rat striatal neurons and HEK293 cells co-expressing A2aR and D2R were treated with A2aR- or D2R-specific agonists. D2R internalization was detected using a biotinylation assay and confocal microscopy. ERK, Src kinase and β-arrestin were measured using Western blotting. The interaction between A2aR and D2R was detected using bioluminescence resonance energy transfer (BRET) and immunoprecipitation. Results: D2R and A2aR were co-localized and formed complexes in striatal neurons, while both the receptors formed heterodimers in the HEK293 cells. In striatal neurons and the HEK293 cells, the D2R agonist quinpirole (1 μmol/L) marked increased Src phosphorylation and β-arrestin recruitment, thereby D2R internalization. Co-treatment with the A2aR antagonist ZM241385 (100 nmol/L) significantly attenuated these D2R-mediated changes. Furthermore, both ZM241385 (100 nmol/L) and the specific Src kinase inhibitor PP2 (5 μmol/L) blocked D2R-mediated ERK phosphorylation. Moreover, expression of the mutant β-arrestin (319-418) significantly attenuated D2R-mediated ERK phosphorylation in HEK293 cells expressing both D2R and A2aR, but not in those expressing D2R alone. Conclusion: A2aR antagonist ZM241385 significantly attenuates D2R internalization and D2R-mediated ERK phosphorylation in striatal neurons, involving Src kinase and β-arrestin. Thus, A2aR/D2R heterodimerization plays important roles in D2R downstream signaling.
    Acta Pharmacologica Sinica 08/2013; 34(10). DOI:10.1038/aps.2013.87 · 2.91 Impact Factor
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    • "Previous studies have demonstrated the dominant-negative mutations of GRK2 to abolish any D2 receptor internalization, evincing the importance of this protein in the downregulation of this receptor [29]. Moreover, arrestin-3 appears to be the isoform which when knocked out in mice models, has shown to inhibit the internalization of D2 receptors in striatal cell cultures [30]. Internalized receptors can be recycled back to the plasma membrane, or targeted for lysosomal degradation. "
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    ABSTRACT: The activity of G protein-coupled receptors (GPCRs) is intricately regulated by a range of intracellular proteins, including G protein-coupled kinases (GRKs) and arrestins. Understanding the effects of ligands on these signaling pathways could provide insights into disease pathophysiologies and treatment. The dopamine D2 receptor is a GPCR strongly implicated in the pathophysiology of a range of neurological and neuropsychiatric disorders, particularly schizophrenia. Previous studies from our lab have shown the preclinical efficacy of a novel allosteric drug, 3(R)- [(2(S)-pyrrolidinylcarbonyl)amino]-2-oxo-1-pyrrolidineacetamide (PAOPA), in attenuating schizophrenia-like behavioural abnormalities in rodent models of the disease. As an allosteric modulator, PAOPA binds to a site on the D2 receptor, which is distinct from the endogenous ligand-binding site, in order to modulate the binding of the D2 receptor ligand, dopamine. The exact signaling pathways affected by this allosteric modulator are currently unknown. The objectives of this study were to decipher the in vivo effects, in rats, of chronic PAOPA administration on D2 receptor regulatory and downstream molecules, including GRK2, arrestin-3 and extracellular receptor kinase (ERK) 1/2. Additionally, an in vitro cellular model was also used to study PAOPA's effects on D2 receptor internalization. Results from western immunoblots showed that chronic PAOPA treatment increased the striatal expression of GRK2 by 41%, arrestin-3 by 34%, phospho-ERK1 by 51% and phospho-ERK2 by 36%. Results also showed that the addition of PAOPA to agonist treatment in cells increased D2 receptor internalization by 33%. This study provides the foundational evidence of putative signaling pathways, and changes in receptor localization, affected by treatment with PAOPA. It improves our understanding on the diverse mechanisms of action of allosteric modulators, while advancing PAOPA's development into a novel drug for the improved treatment of schizophrenia.
    PLoS ONE 08/2013; 8(8):e70736. DOI:10.1371/journal.pone.0070736 · 3.23 Impact Factor
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    • "PET studies in rodents have given evidence that D2/D3R internalization might explain why amphetamine-induced decreases in striatal [ 11 C]raclopride binding are more protracted than the amphetamine-induced DA increases (Sun et al., 2003; Ginovart et al., 2004). Specifically, in mice lacking β-arrestin-2 (arrestin3), which is necessary for D2R internalization (Skinbjerg et al., 2009), the decreases in striatal binding of a D2R agonist PET ligand ([ 11 C]MNPA) or a D2R antagonist ([ 18 F]fallypride) induced by amphetamine recovered 4 hours after its administration whereas they remained decreased in wild-type mice (Skinbjerg et al., 2010). "
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    ABSTRACT: Dopamine D2 receptors are involved with wakefulness, but their role in the decreased alertness associated with sleep deprivation is unclear. We had shown that sleep deprivation reduced dopamine D2/D3 receptor availability (measured with PET and [(11)C]raclopride in controls) in striatum, but could not determine whether this reflected dopamine increases ([(11)C]raclopride competes with dopamine for D2/D3 receptor binding) or receptor downregulation. To clarify this, we compared the dopamine increases induced by methylphenidate (a drug that increases dopamine by blocking dopamine transporters) during sleep deprivation versus rested sleep, with the assumption that methylphenidate's effects would be greater if, indeed, dopamine release was increased during sleep deprivation. We scanned 20 controls with [(11)C]raclopride after rested sleep and after 1 night of sleep deprivation; both after placebo and after methylphenidate. We corroborated a decrease in D2/D3 receptor availability in the ventral striatum with sleep deprivation (compared with rested sleep) that was associated with reduced alertness and increased sleepiness. However, the dopamine increases induced by methylphenidate (measured as decreases in D2/D3 receptor availability compared with placebo) did not differ between rested sleep and sleep deprivation, and were associated with the increased alertness and reduced sleepiness when methylphenidate was administered after sleep deprivation. Similar findings were obtained by microdialysis in rodents subjected to 1 night of paradoxical sleep deprivation. These findings are consistent with a downregulation of D2/D3 receptors in ventral striatum with sleep deprivation that may contribute to the associated decreased wakefulness and also corroborate an enhancement of D2 receptor signaling in the arousing effects of methylphenidate in humans.
    The Journal of Neuroscience : The Official Journal of the Society for Neuroscience 05/2012; 32(19):6711-7. DOI:10.1523/JNEUROSCI.0045-12.2012 · 6.34 Impact Factor
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