Adaptor protein-2 interaction with arrestin regulates GPCR recycling and apoptosis

Traffic. 2009 Sep;10(9):1286-300. doi: 10.1111/j.1600-0854.2009.00957.x. Epub 2009 Jun 15.

Abstract

G protein-coupled receptors (GPCRs) are integral to cellular function in nearly all physiologic and many pathologic processes. GPCR signaling represents an intricate balance between receptor activation, inactivation (desensitization, internalization and degradation) and resensitization (recycling and de novo synthesis). Complex formation between phosphorylated GPCRs, arrestins and an ever-increasing number of effector molecules is known to regulate cellular function. Previous studies have demonstrated that, although N-formyl peptide receptor (FPR) internalization occurs in the absence of arrestins, FPR recycling is arrestin-dependent. Furthermore, FPR stimulation in the absence of arrestins leads to receptor accumulation in perinuclear endosomes and apoptosis. In this study, we show that the interaction of GPCR-bound arrestin with adaptor protein-2 (AP-2) is a critical anti-apoptotic event. In addition, AP-2 associates with the receptor-arrestin complex in perinuclear endosomes and is required for proper post-endocytic GPCR trafficking. Finally, we observed that depletion of endogenous AP-2 results in the initiation of apoptosis upon stimulation of multiple GPCRs, including P2Y purinergic receptors and CXCR2, but not CXCR4. We propose a model in which the abnormal accumulation of internalized GPCR-arrestin complexes in recycling endosomes, resulting from defective arrestin-AP-2 interactions, leads to the specific initiation of aberrant signaling pathways and apoptosis.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adaptor Protein Complex 2 / genetics
  • Adaptor Protein Complex 2 / metabolism*
  • Apoptosis / physiology*
  • Arrestins / genetics
  • Arrestins / metabolism*
  • Blotting, Western
  • Endosomes / metabolism
  • Green Fluorescent Proteins / genetics
  • Humans
  • Immunoprecipitation
  • Microscopy, Fluorescence
  • Protein Binding
  • Protein Transport
  • Receptors, Formyl Peptide / genetics
  • Receptors, Formyl Peptide / metabolism*
  • Receptors, G-Protein-Coupled / biosynthesis*
  • Receptors, G-Protein-Coupled / metabolism
  • Transfection
  • U937 Cells

Substances

  • Adaptor Protein Complex 2
  • Arrestins
  • Receptors, Formyl Peptide
  • Receptors, G-Protein-Coupled
  • Green Fluorescent Proteins