RT Journal Article SR Electronic T1 Arrestin recruitment to CCR5: potent CCL5 analogs reveal differences in dependence on receptor phosphorylation and isoform-specific recruitment bias JF Molecular Pharmacology JO Mol Pharmacol FD American Society for Pharmacology and Experimental Therapeutics SP MOLPHARM-AR-2020-000036 DO 10.1124/molpharm.120.000036 A1 Elsa Martins A1 Hellena Brodier A1 Irène Rossitto-Borlat A1 Ilke Ilgaz A1 Mélanie Villard A1 Oliver Hartley YR 2020 UL http://molpharm.aspetjournals.org/content/early/2020/09/17/molpharm.120.000036.abstract AB CCR5 is a chemokine receptor belonging to the GPCR superfamily. An established anti-HIV drug target, CCR5 is attracting significant additional interest in both cancer and neuroinflammation. Several N-terminally engineered analogs of CCL5, a natural ligand of CCR5, are highly potent CCR5 inhibitors. The inhibitory mechanisms of certain analogs relate to modulation of receptor desensitization, but the cellular and molecular mechanisms have not been fully elucidated. Here we made use of a collection of CCR5 phosphorylation mutants and arrestin variants to investigate how CCL5 analogs differ from CCL5 in their capacity to elicit both CCR5 phosphorylation and arrestin recruitment, with reference to the current 'core' and 'tail' interaction model for arrestin-GPCR interaction. We showed that CCL5 elicits recruitment of both arrestin 2 and arrestin 3 to CCR5 with recruitment, particularly of arrestin 2, strongly dependent on the arrestin tail interaction. 5P12-RANTES does not elicit receptor phosphorylation or arrestin recruitment. In contrast, PSC-RANTES induces CCR5 hyper-phosphorylation, driving enhanced arrestin recruitment with lower dependence on the arrestin tail interaction. 5P14-RANTES induces comparable levels of receptor phosphorylation to CCL5, but arrestin recruitment is absolutely dependent on the arrestin tail interaction, and in one of the cellular backgrounds used, recruitment showed isoform bias towards arrestin 3 versus arrestin 2. No evidence for ligand-specific differences in receptor phosphorylation patterns across the four implicated serine residues was observed. Our results improve understanding of the molecular pharmacology of CCR5 and help further elucidate the inhibitory mechanisms of a group of potent inhibitors. Significance Statement CCR5 is a key drug target for HIV, cancer and inflammation. Highly potent chemokine analog inhibitors act via the modulation of receptor desensitization, a process initiated by the recruitment of arrestin proteins. This study shows that potent CCL5 analogs differ from each other and from the parent chemokine in the extent and quality of CCR5-arrestin association that they elicit, providing valuable insights into CCR5 pharmacology and cell biology that will facilitate the development of new medicines targeting this important receptor.