Discovery and characterization of a G protein-biased agonist that inhibits β-arrestin recruitment to the D2 dopamine receptor.

Methods Development
Medicinal Chemistry


A high-throughput screening campaign was conducted to interrogate a 380,000+ small-molecule library for novel D2 dopamine receptor modulators using a calcium mobilization assay. Active agonist compounds from the primary screen were examined for orthogonal D2 dopamine receptor signaling activities including cAMP modulation and β-arrestin recruitment. Although the majority of the subsequently confirmed hits activated all signaling pathways tested, several compounds showed a diminished ability to stimulate β-arrestin recruitment. One such compound (MLS1547; 5-chloro-7-[(4-pyridin-2-ylpiperazin-1-yl)methyl]quinolin-8-ol) is a highly efficacious agonist at D2 receptor-mediated G protein-linked signaling, but does not recruit β-arrestin as demonstrated using two different assays. This compound does, however, antagonize dopamine-stimulated β-arrestin recruitment to the D2 receptor. In an effort to investigate the chemical scaffold of MLS1547 further, we characterized a set of 24 analogs of MLS1547 with respect to their ability to inhibit cAMP accumulation or stimulate β-arrestin recruitment. A number of the analogs were similar to MLS1547 in that they displayed agonist activity for inhibiting cAMP accumulation, but did not stimulate β-arrestin recruitment (i.e., they were highly biased). In contrast, other analogs displayed various degrees of G protein signaling bias. These results provided the basis to use pharmacophore modeling and molecular docking analyses to build a preliminary structure-activity relationship of the functionally selective properties of this series of compounds. In summary, we have identified and characterized a novel G protein-biased agonist of the D2 dopamine receptor and identified structural features that may contribute to its biased signaling properties.


Free, R Benjamin; Chun, Lani S; Moritz, Amy E; Miller, Brittney N; Doyle, Trevor B; Conroy, Jennie L; Padron, Adrian; Meade, Julie A; Xiao, Jingbo; Hu, Xin; Dulcey, Andrés E; Han, Yang; Duan, Lihua; Titus, Steve; Bryant-Genevier, Melanie; Barnaeva, Elena; Ferrer-Alegre, Marc; Javitch, Jonathan A; Beuming, Thijs; Shi, Lei; Southall, Noel; Marugan, Juan; Sibley, David R;


  • Animals
  • Arrestins/ antagonists & inhibitors
  • Arrestins/ metabolism
  • CHO Cells
  • Cell Line
  • Cricetulus
  • Cyclic AMP/ metabolism
  • GTP-Binding Proteins/ metabolism
  • HEK293 Cells
  • Humans
  • Protein Binding/ physiology
  • Receptors, Dopamine D2/ metabolism
  • Signal Transduction/ physiology
  • Small Molecule Libraries
  • Structure-Activity Relationship

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