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A non-GPCR-binding partner interacts with a novel surface on β-arrestin1 to mediate GPCR signaling

Ya Zhuo1, Vsevolod V Gurevich2, Sergey A Vishnivetskiy2

  • 1Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.

The Journal of Biological Chemistry
|August 6, 2020
PubMed

Insights

Signal-transducing adaptor molecule 1 (STAM1) binds a novel surface on β-arrestin1 (β-arr1) to activate focal adhesion kinase (FAK) and promote cell migration. This interaction is crucial for G protein-coupled receptor (GPCR) signaling.

Area of Science:

  • Cellular signaling
  • Molecular biology
  • Biophysics

Background:

  • β-arrestin1 (β-arr1) is a multifaceted adaptor protein involved in G protein-coupled receptor (GPCR) signaling.
  • β-arr1 facilitates chemotaxis by promoting focal adhesion kinase (FAK) activation downstream of the chemokine receptor CXCR4.
  • The adaptor protein signal-transducing adaptor molecule 1 (STAM1) is essential for this β-arr1 function.

Purpose of the Study:

  • To elucidate the mechanism by which β-arr1 and STAM1 cooperate to activate FAK.
  • To identify the specific binding site of STAM1 on β-arr1.
  • To understand the role of this interaction in GPCR-mediated signaling.

Main Methods:

  • Site-directed spin-labeling Electron Paramagnetic Resonance (EPR) spectroscopy.
  • Bioluminescence Resonance Energy Transfer (BRET) cellular studies.
  • Expression of mutant β-arr1 forms deficient in STAM1 binding.

Main Results:

  • STAM1 binds to a novel surface at the base of β-arr1's finger loop, distinct from the receptor-binding site.
  • Disruption of the STAM1-β-arr1 interaction impairs CXCR4-mediated FAK activation and chemotaxis.
  • A STAM1-binding deficient β-arr1 mutant retained CXCR4 binding but significantly reduced CXCL12-induced FAK activation, without affecting ERK-1/2 activation.

Conclusions:

  • A novel interaction surface on β-arr1, at the base of the finger loop, mediates non-GPCR interactions crucial for β-arrestin signaling.
  • This surface acts as a switch, engaging effector molecules like STAM1 to drive β-arrestin-dependent pathways.
  • The findings reveal a new mechanism for regulating GPCR signaling specificity through β-arrestin adaptor proteins.
Keywords:
CXC-chemokine receptor type 4 (CXCR4)G protein–coupled receptor (GPCR)PTK2 protein-tyrosine kinase 2 (PTK2)arrestinarrestin signalingbioluminescence resonance energy transfer (BRET)electron paramagnetic resonance (EPR)focal adhesion kinase (FAK)

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