Dopamine Receptor-Interacting Protein 78 Acts as a Molecular Chaperone for CCR5 Chemokine Receptor Signaling Complex Organization

Yi-Qun Kuang,Kathleen M Attwood,Patrick J Holland,Jennifer Frazer,Denis J Dupré,Graham Dellaire,Nicholle Charette,Paul Proost

doi:10.1371/journal.pone.0040522

Yi-Qun Kuang, Kathleen M Attwood + Show 6 more

Open Access

https://doi.org/10.1371/journal.pone.0040522

Copy DOI

Journal: PloS one	Publication Date: Jul 16, 2012
Citations: 46	License type: CC BY 4.0

Affiliation: Dalhousie University

Abstract

Chemokine receptors are members of the G protein-coupled receptor (GPCR) family. CCR5 and CXCR4 act as co-receptors for human immunodeficiency virus (HIV) and several efforts have been made to develop ligands to inhibit HIV infection by blocking those receptors. Removal of chemokine receptors from the cell surface using polymorphisms or other means confers some levels of immunity against HIV infection. Up to now, very limited success has been obtained using ligand therapies so we explored potential avenues to regulate chemokine receptor expression at the plasma membrane. We identified a molecular chaperone, DRiP78, that interacts with both CXCR4 and CCR5, but not the heterodimer formed by these receptors. We further characterized the effects of DRiP78 on CCR5 function. We show that the molecular chaperone inhibits CCR5 localization to the plasma membrane. We identified the interaction region on the receptor, the F(x)6LL motif, and show that upon mutation of this motif the chaperone cannot interact with the receptor. We also show that DRiP78 is involved in the assembly of CCR5 chemokine signaling complex as a homodimer, as well as with the Gαi protein. Finally, modulation of DRiP78 levels will affect receptor functions, such as cell migration in cells that endogenously express CCR5. Our results demonstrate that modulation of the functions of a chaperone can affect signal transduction at the cell surface.

Highlights

Chemokine receptors are a specialized subset of the superfamily of seven transmembrane proteins, coupled to the heterotrimeric G protein
Dopamine Receptor-interacting Protein 78 (DRiP78) Interaction with Chemokine Receptors Our group and others have previously described that CCR5 and CXCR4 can interact together to form a receptor signalling complex at plasma membrane [3,18,19]
While performing a screen with proteins known to regulate G protein coupled receptors (GPCR) signaling or trafficking for targets interacting with chemokine receptor dimers, we identified DRiP78 as a potential interactor of CCR5

Summary

Introduction

Chemokine receptors are a specialized subset of the superfamily of seven transmembrane proteins, coupled to the heterotrimeric G protein. While we know very well that G protein coupled receptors (GPCR) signal via multiple proteins assembled into a complex, chemokine receptors are left largely uncharacterized in terms of their association with signaling partners and anterograde trafficking to the plasma membrane. Oligomerization of GPCRs has been shown for several receptors including CCR5 and CXCR4 [3,4,5,6,7], very little is known about the factors or proteins that will influence receptor oligomerization, and how specificity of signalling complex organization is attained. Allosteric modulation of ligand binding, alteration in G protein signaling and coupling are all associated with GPCR oligomerization [8]. Receptor oligomerization likely occurs via a defined sequence of events, as is the assembly of the different signalling partners [9,10,11]. While screening for interactions between chaperones/ scaffold proteins and GPCRs, we observed the interaction of a molecular chaperone, DRiP78, with both chemokine receptors CCR5 and CXCR4

Methods

Results

Conclusion