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Phosphorylation of the delta-opioid receptor regulates its beta-arrestins selectivity and subsequent receptor

Yu Qiu1, Horace H Loh, Ping-Yee Law

  • 1Department of Pharmacology, University of Minnesota Medical School, Minneapolis, Minnesota 55455, USA. qiuxx014@umn.edu

The Journal of Biological Chemistry
|June 15, 2007
PubMed

Insights

Receptor phosphorylation guides delta-opioid receptor (DOR) to beta-arrestin 2, influencing signaling and internalization without altering complex stability or receptor fate.

Area of Science:

  • Pharmacology
  • Cell Biology
  • Molecular Biology

Background:

  • Delta-opioid receptor (DOR) signaling and trafficking are crucial for pain modulation.
  • Receptor phosphorylation and beta-arrestins are known regulators of G protein-coupled receptor (GPCR) function.
  • Understanding these interactions is key to developing targeted therapeutics.

Purpose of the Study:

  • To investigate the specific roles of receptor phosphorylation and beta-arrestins in DOR signaling and trafficking.
  • To elucidate how C-terminal phosphorylation affects DOR interaction with beta-arrestins and subsequent cellular responses.
  • To determine the impact of phosphorylation on DOR internalization, desensitization, and recycling kinetics.

Main Methods:

  • Utilized a mutant delta-opioid receptor (DOR) with C-terminal Ser/Thr residues mutated to Alanine (DTS).
  • Employed dominant-negative dynamin (dynamin K44E) to block receptor internalization.
  • Used beta-arrestin-depleted mouse embryonic fibroblast (MEF) cells and BRET assays to assess receptor-beta-arrestin interactions and signaling.
  • Administered DOR agonist D-[Pen(2),Pen(5)]enkephalin to study receptor dynamics.

Main Results:

  • The DOR DTS mutant showed slower agonist-induced internalization and adenylyl cyclase (AC) desensitization compared to wild-type DOR.
  • Depletion of beta-arrestins significantly inhibited both internalization and AC desensitization of the DTS mutant.
  • Phosphorylation promoted DOR selectivity for beta-arrestin 2 over beta-arrestin 1.
  • In beta-arrestin knockout cells, DOR desensitization was impaired in beta-arrestin 2-deficient cells, while internalization was reduced in both knockout types.
  • Phosphorylation did not affect the stability of the DOR-beta-arrestin complex or the recycling of internalized receptors.

Conclusions:

  • Receptor phosphorylation is critical for conferring delta-opioid receptor selectivity towards beta-arrestin 2.
  • This phosphorylation event influences receptor internalization and desensitization but not the stability of the receptor-beta-arrestin complex or the ultimate fate of the internalized receptor.
  • These findings provide insights into the precise mechanisms governing DOR signaling and trafficking, potentially informing future drug development.

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