The dopamine D2 receptor can directly recruit and activate GRK2 without G protein activation.

Published

Journal Article

The dopamine D2 receptor (D2R) is a G protein-coupled receptor (GPCR) that is critical for many central nervous system functions. The D2R carries out these functions by signaling through two transducers: G proteins and β-arrestins (βarrs). Selectively engaging either the G protein or βarr pathway may be a way to improve drugs targeting GPCRs. The current model of GPCR signal transduction posits a chain of events where G protein activation ultimately leads to βarr recruitment. GPCR kinases (GRKs), which are regulated by G proteins and whose kinase action facilitates βarr recruitment, bridge these pathways. Therefore, βarr recruitment appears to be intimately tied to G protein activation via GRKs. Here we sought to understand how GRK2 action at the D2R would be disrupted when G protein activation is eliminated and the effect of this on βarr recruitment. We used two recently developed biased D2R mutants that can preferentially interact either with G proteins or βarrs as well as a βarr-biased D2R ligand, UNC9994. With these functionally selective tools, we investigated the mechanism whereby the βarr-preferring D2R achieves βarr pathway activation in the complete absence of G protein activation. We describe how direct, G protein-independent recruitment of GRK2 drives interactions at the βarr-preferring D2R and also contributes to βarr recruitment at the WT D2R. Additionally, we found an additive interaction between the βarr-preferring D2R mutant and UNC9994. These results reveal that the D2R can directly recruit GRK2 without G protein activation and that this mechanism may have relevance to achieving βarr-biased signaling.

Full Text

Duke Authors

Cited Authors

  • Pack, TF; Orlen, MI; Ray, C; Peterson, SM; Caron, MG

Published Date

  • April 20, 2018

Published In

Volume / Issue

  • 293 / 16

Start / End Page

  • 6161 - 6171

PubMed ID

  • 29487132

Pubmed Central ID

  • 29487132

Electronic International Standard Serial Number (EISSN)

  • 1083-351X

Digital Object Identifier (DOI)

  • 10.1074/jbc.RA117.001300

Language

  • eng

Conference Location

  • United States