Signaling-Biased and Constitutively Active Dopamine D2 Receptor Variant

Dayana Rodriguez-Contreras, Alec F. Condon, David C. Buck, Naeem Asad, Timothy M. Dore, Dineke S. Verbeek, Marina A.J. Tijssen, Ujwal Shinde, John T. Williams, Kim Neve

Research output: Contribution to journalArticlepeer-review

Abstract

A dopamine D2 receptor mutation was recently identified in a family with a novel hyperkinetic movement disorder. Compared to the wild type D2 receptor, the novel allelic variant D2-I212F activates a Gαi1β1γ2 heterotrimer with higher potency and modestly enhanced basal activity in human embryonic kidney (HEK) 293 cells and has decreased capacity to recruit arrestin3. We now report that omitting overexpressed G protein-coupled receptor kinase-2 (GRK2) decreased the potency and efficacy of quinpirole for arrestin recruitment. The relative efficacy of quinpirole for arrestin recruitment to D2-I212F compared to D2-WT was considerably lower without overexpressed GRK2 than with added GRK2. D2-I212F exhibited higher basal activation of GαoA than Gαi1 but little or no increase in the potency of quinpirole relative to D2-WT. Other signs of D2-I212F constitutive activity for G protein-mediated signaling, in addition to basal activation of Gαi/o, were enhanced basal inhibition of forskolin-stimulated cyclic AMP accumulation that was reversed by the inverse agonists sulpiride and spiperone and a ∼4-fold increase in the apparent affinity of D2-I212F for quinpirole, determined from competition binding assays. In mouse midbrain slices, inhibition of tonic current by the inverse agonist sulpiride in dopamine neurons expressing D2-I212F was consistent with our hypothesis of enhanced constitutive activity and sensitivity to dopamine relative to D2-WT. Molecular dynamics simulations with D2 receptor models suggested that an ionic lock between the cytoplasmic ends of the third and sixth α-helices that constrains many G protein-coupled receptors in an inactive conformation spontaneously breaks in D2-I212F. Overall, these results confirm that D2-I212F is a constitutively active and signaling-biased D2 receptor mutant and also suggest that the effect of the likely pathogenic variant in a given brain region will depend on the nature of G protein and GRK expression.

Original languageEnglish (US)
Pages (from-to)1873-1884
Number of pages12
JournalACS Chemical Neuroscience
Volume12
Issue number11
DOIs
StatePublished - Jun 2 2021

Keywords

  • D2 receptor
  • Dopamine
  • G protein
  • allelic variant
  • arrestin
  • biased signaling
  • constitutive activity

ASJC Scopus subject areas

  • Biochemistry
  • Physiology
  • Cognitive Neuroscience
  • Cell Biology

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