Structural Insights into β-arrestin/CB1 Receptor Interaction: NMR and CD Studies on Model Peptides.

Paula Morales,M Angeles Jiménez,Marta Bruix

doi:10.3390/ijms21218111

Abstract

Activation of the cannabinoid CB1 receptor induces different cellular signaling cascades through coupling to different effector proteins (G-proteins and β-arrestins), triggering numerous therapeutic effects. Conformational changes and rearrangements at the intracellular domain of this GPCR receptor that accompany ligand binding dictate the signaling pathways. The GPCR-binding interface for G proteins has been extensively studied, whereas β-arrestin/GPCR complexes are still poorly understood. To gain knowledge in this direction, we designed peptides that mimic the motifs involved in the putative interacting region: β-arrestin1 finger loop and the transmembrane helix 7-helix 8 (TMH7-H8) elbow located at the intracellular side of the CB1 receptor. According to circular dichroism and NMR data, these peptides form a native-like, helical conformation and interact with each other in aqueous solution, in the presence of trifluoroethanol, and using zwitterionic detergent micelles as membrane mimics. These results increase our understanding of the binding mode of β-arrestin and CB1 receptor and validate minimalist approaches to structurally comprehend complex protein systems.

Highlights

The therapeutic effects of cannabinoids have long been known; it was not until a few decades ago that their mechanism of action was elucidated
Since no experimental structure of the CB1/β-arrestin complex has been reported to date, the design of peptides that mimic the interacting motifs in the CB1/β-arrestin1 complex was based on previously reported data on G protein-coupled receptor (GPCR)/arrestin interface
The sequence for the β-arrestin1 model peptide was selected as the shortest sequence having the highest helical tendency and being the most soluble at the neutral pH values used in the nuclear magnetic resonance (NMR) study

Summary

Introduction

The therapeutic effects of cannabinoids have long been known; it was not until a few decades ago that their mechanism of action was elucidated. In the late 1980s, receptors targeted by phytocannabinoids were identified in rat brain [1] Subsequent cloning of this G protein-coupled receptor (GPCR) consolidated the discovery of the first cannabinoid receptor, CB1 [2]. CB1 receptors are found in the peripheral nervous system, as well as in other organs and tissues including endocrine glands, spleen, heart or the gastrointestinal tract. This expression pattern confers upon CB1 a relevant role in the modulation of numerous physiopathological processes including memory processing, pain regulation or neurodegeneration [3,4,5,6]. A growing body of research supports the notion that CB1 represents a promising target for the development of novel drugs for the treatment of diverse pathologies including neurodegenerative, cancer or metabolic disorders [7,8,9,10,11,12,13,14,15]

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