Abstract
CCR5 stimulation with natural ligands, such as RANTES, classically induces short-term internalization with transient activation of β-arrestins and rapidly recycling on the cell surface. Here we discovered that, in T cells, natural CCR5 antibodies induce a CCR5-negative phenotype with the involvement of β-arrestin2, which leads to the formation of a stable CCR5 signalosome with both β-arrestin2 and ERK1. The activation of β-arrestin2 is necessary to CCR5 signaling for the signalosome formation and stabilization. When all stimuli were washed out, β-arrestin1 silencing favors the activity of β-arrestin2 for the CCR5 signalosome retention. Interestingly, CCR5 turn from Class A trafficking pattern, normally used for its internalization with natural modulating molecules (i.e. RANTES), into a long lasting Class B type specifically induced by stimulation with natural anti-CCR5 antibodies. This new CCR5 pathway is relevant not only to study in depth the molecular basis of all pathologies where CCR5 is involved but also to generate new antidody-based therapeutics.
Highlights
The seven-transmembrane receptors (7TMRs, called G protein-coupled receptors, GPCRs) are the largest known group of integral membrane receptor proteins with important physiological and pathological functions
7TMRs can be functionally divided into two general categories based on the stability of interaction with β-arrestins following agonist activation: (i) “Class A” receptors, such as β2 adrenergic receptor (β2 AR), form transient complexes with β-arrestin, show its transient ubiquination with weak induction of ERK1/2 activity; in contrast (ii) “Class B” receptors, including vasopressin V2 receptor (V2R), form tight receptor- β-arrestin complexes, mediated by its sustained ubiquitination and a strong ERK1/2 activity that is concentrated on endosomes
The cells were incubated for 30′with Rantes and with chemokine receptor 5 (CCR5) Ab Pos or not, washed and incubated for a further 120′(i.e., incubation for this group totaled 150′), t0, and for 48 h (t1); these two time points have been chosen on the basis of our previous findings[21]; briefly, 150′corresponds to the initial internalization of the receptor and 48 h is required to achieve complete CCR5 internalization
Summary
The seven-transmembrane receptors (7TMRs, called G protein-coupled receptors, GPCRs) are the largest known group of integral membrane receptor proteins with important physiological and pathological functions. The conformational changes induced by GPCRs in β-arrestins, especially when they assemble with the phosphorylated domains of the receptor, could lead to the transmission of signals to downstream kinases, such as mitogen-activated-protein kinases (MAPKs), Raf, MEK1, phosphoinositol-3-kinase (PI3K), Akt[7,8,9,10]. These modifications include: (i) phosphorylation, (ii) ubiquitination, (iii) SUMOylation, (iv) S-nitrosylation, and (v) acetylation[11]. The CC chemokine receptor 5 (CCR5), belonging to the GPCRs family, regulates trafficking and effector functions of immune cells[16], and is the main coreceptor of HIV, in association with CD417
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
