The Abrogation of Phosphorylation Plays a Relevant Role in the CCR5 Signalosome Formation with Natural Antibodies to CCR5.

Assunta Venuti,Lucia Lopalco,Maria Teresa Sciortino,Agostino Riva,Rosamaria Pennisi,Massimo Tommasino,Claudia Pastori,Gabriel Siracusano

doi:10.3390/v10010009

Abstract

The exposure to CCR5 (CC chemokine receptor 5) specific natural antibodies in vitro produces a Class B β-arrestin2-dependent CCR5 retention with the aid of ERK1, due to the formation of a CCR5 signalosome, which remains stable for at least 48 h. Considering that β-arrestins and MAPKs are receptive to environmental signals, their signal complexes could be one of the key junction for GPCRs internalization related signal transduction. Here, we demonstrate that, in T cells, the phosphorylation status of either CCR5 receptor or ERK1 protein is necessary to drive the internalized receptor into the early endosomes, forming the CCR5 signalosome. In particular, our data show that β-arrestin2/ERK1 complex is a relevant transducer in the CCR5 signaling pathway. Understanding the mechanism of CCR5 regulation is essential for many inflammatory disorders, tumorigenesis and viral infection such as HIV.

Highlights

Chemokine receptors belong to seven-transmembrane proteins (7TMRs, called G-protein coupled receptors, GPCRs), which play a fundamental role in a multiplicity of developmental and chemotactic events [1,2].After stimulation, these receptors activate a restricted number of effectors, which influence the intracellular concentrations of second messengers and their relative target proteins, including protein kinase A (PKA), protein kinase C (PKC) and the related substrates.This in turn results in regulation of several cellular functions, via heterotrimeric G proteins, and G protein-dependent and -independent activation of mitogen activated protein kinases (MAPKs), including the extracellular signal-regulated kinase (ERK) cascade [3]
It is well demonstrated that natural antibodies to chemokine receptor 5 (CCR5) receptor (CCR5 Ab Pos), detected in the sera of Long Term Non-Progressor subjects (LTNPs), induce a long-lasting internalization (48 h) with the recruitment of β-arrestin2 and ERK1 proteins [9,10,11]
Taking into account that cellular signaling pathways trigger protein–protein interactions mediated by phosphorylation and dephosphorylation events [15], here we wondered if the inhibition of specific kinases activity may affect the CCR5 internalization mediated by the agonist-induced β-arrestin-ERK interaction

Summary

Introduction

Chemokine receptors belong to seven-transmembrane proteins (7TMRs, called G-protein coupled receptors, GPCRs), which play a fundamental role in a multiplicity of developmental and chemotactic events [1,2].After stimulation, these receptors activate a restricted number of effectors (e.g., adenylate cyclase and phospholipase C), which influence the intracellular concentrations of second messengers (e.g., inositol 1,4,5 trisphosphate, cyclic AMP, diacylglycerol, and Ca2+ ) and their relative target proteins, including protein kinase A (PKA), protein kinase C (PKC) and the related substrates.This in turn results in regulation of several cellular functions, via heterotrimeric G proteins, and G protein-dependent and -independent activation of mitogen activated protein kinases (MAPKs), including the extracellular signal-regulated kinase (ERK) cascade [3]. Chemokine receptors belong to seven-transmembrane proteins (7TMRs, called G-protein coupled receptors, GPCRs), which play a fundamental role in a multiplicity of developmental and chemotactic events [1,2] After stimulation, these receptors activate a restricted number of effectors (e.g., adenylate cyclase and phospholipase C), which influence the intracellular concentrations of second messengers (e.g., inositol 1,4,5 trisphosphate, cyclic AMP, diacylglycerol, and Ca2+ ) and their relative target proteins, including protein kinase A (PKA), protein kinase C (PKC) and the related substrates. These receptors activate a restricted number of effectors (e.g., adenylate cyclase and phospholipase C), which influence the intracellular concentrations of second messengers (e.g., inositol 1,4,5 trisphosphate, cyclic AMP, diacylglycerol, and Ca2+ ) and their relative target proteins, including protein kinase A (PKA), protein kinase C (PKC) and the related substrates This in turn results in regulation of several cellular functions, via heterotrimeric G proteins, and . Human CC chemokine receptor 5 (CCR5), a member of the superfamily of 7TMRs, has been identified as the receptor for chemokines such as MIP-1α (Macrophage inflammatory protein 1α, CCL3), MIP-1β (Macrophage inflammatory protein-1β, CCL4), RANTES (Regulated on Activation, Normal T Cell Expressed and Secreted, CCL5) [7], and serves as a coreceptor for the entry of R5-HIV-1 strains into the cells, in association with CD4 [8]

Methods

Results

Conclusion