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Parallel Interrogation of β-Arrestin2 Recruitment for Ligand Screening on a GPCR-Wide Scale using PRESTO-Tango Assay
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Divergent β-arrestin-dependent signaling events are dependent upon sequences within G-protein-coupled receptor C

Kasturi Pal1, Maneesh Mathur, Puneet Kumar

  • 1Cell Molecular Developmental Biology Program, University of California, Riverside, California 92521, USA.

The Journal of Biological Chemistry
|December 14, 2012
PubMed

Insights

Beta-arrestin (β-arrestin) interactions with G-protein-coupled receptors (GPCRs) dictate distinct signaling outcomes. Receptor C-termini and phosphorylation sites critically control β-arrestin recruitment rate, magnitude, and downstream effects.

Area of Science:

  • Molecular Cell Biology
  • G-protein Coupled Receptor Signaling
  • Signal Transduction

Background:

  • Beta-arrestins (β-arrestins) are key adaptor proteins mediating G-protein-coupled receptor (GPCR) desensitization and internalization.
  • GPCR activation of β-arrestins can trigger distinct signaling pathways independent of canonical G-protein cascades.
  • The specific GPCR dictates the downstream signaling outcome initiated by β-arrestin recruitment.

Purpose of the Study:

  • To investigate how different GPCRs, specifically protease-activated receptor-2 (PAR(2)) and neurokinin-1 receptor (NK1R), differentially engage β-arrestins.
  • To elucidate the molecular determinants governing the rate, affinity, and signaling consequences of β-arrestin recruitment to PAR(2) versus NK1R.
  • To determine the role of receptor C-terminal interactions and phosphorylation in dictating β-arrestin-mediated signaling outcomes.

Main Methods:

  • Real-time monitoring of receptor/β-arrestin interactions using bioluminescence resonance energy transfer (BRET).
  • Utilized chimeric receptors (PAR(2)/NK1R) and site-directed mutagenesis (PAR(2) Ser/Thr mutant) to probe interaction domains.
  • Investigated the dependence of β-arrestin recruitment on Gα(q) signaling intermediates.

Main Results:

  • PAR(2) exhibited higher apparent affinity and faster recruitment kinetics for β-arrestins compared to NK1R, leading to more rapid G-protein signal desensitization.
  • PAR(2) β-arrestin recruitment was independent of prior Gα(q) signaling, whereas NK1R recruitment was sensitive to Gα(q) inhibition.
  • Specific phosphoresidues within the C-termini of PAR(2) and NK1R critically determined the rate and magnitude of β-arrestin recruitment and subsequent signaling.

Conclusions:

  • The intrinsic properties of the C-terminal tail of GPCRs, particularly specific phosphorylation sites, are crucial determinants of β-arrestin recruitment dynamics.
  • Differential β-arrestin engagement by PAR(2) and NK1R underlies their distinct downstream signaling pathways, affecting cellular processes like ERK1/2 activation, cofilin activation, cell migration, and proliferation.
  • Understanding these receptor-specific interactions provides insights into targeted therapeutic strategies for GPCR-mediated diseases.

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