A new inhibitor of the β-arrestin/AP2 endocytic complex reveals interplay between GPCR internalization and signalling

Nat Commun. 2017 Apr 18;8:15054. doi: 10.1038/ncomms15054.

Abstract

In addition to G protein-coupled receptor (GPCR) desensitization and endocytosis, β-arrestin recruitment to ligand-stimulated GPCRs promotes non-canonical signalling cascades. Distinguishing the respective contributions of β-arrestin recruitment to the receptor and β-arrestin-promoted endocytosis in propagating receptor signalling has been limited by the lack of selective analytical tools. Here, using a combination of virtual screening and cell-based assays, we have identified a small molecule that selectively inhibits the interaction between β-arrestin and the β2-adaptin subunit of the clathrin adaptor protein AP2 without interfering with the formation of receptor/β-arrestin complexes. This selective β-arrestin/β2-adaptin inhibitor (Barbadin) blocks agonist-promoted endocytosis of the prototypical β2-adrenergic (β2AR), V2-vasopressin (V2R) and angiotensin-II type-1 (AT1R) receptors, but does not affect β-arrestin-independent (transferrin) or AP2-independent (endothelin-A) receptor internalization. Interestingly, Barbadin fully blocks V2R-stimulated ERK1/2 activation and blunts cAMP accumulation promoted by both V2R and β2AR, supporting the concept of β-arrestin/AP2-dependent signalling for both G protein-dependent and -independent pathways.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Protein Complex beta Subunits / metabolism
  • Animals
  • Cell Membrane / metabolism
  • Clathrin-Coated Vesicles / metabolism
  • Cyclic AMP / metabolism
  • Endocytosis / drug effects*
  • Enzyme Activation / drug effects
  • Extracellular Signal-Regulated MAP Kinases / metabolism
  • HEK293 Cells
  • Humans
  • Models, Biological
  • Protein Binding / drug effects
  • Rats
  • Receptors, G-Protein-Coupled / agonists
  • Receptors, G-Protein-Coupled / metabolism*
  • Signal Transduction* / drug effects
  • Small Molecule Libraries / chemistry
  • Small Molecule Libraries / pharmacology*
  • beta-Arrestins / metabolism*

Substances

  • Adaptor Protein Complex beta Subunits
  • Receptors, G-Protein-Coupled
  • Small Molecule Libraries
  • beta-Arrestins
  • Cyclic AMP
  • Extracellular Signal-Regulated MAP Kinases