PT  - JOURNAL ARTICLE
AU  - Lagane, Bernard
AU  - Ballet, Sébastien
AU  - Planchenault, Thierry
AU  - Balabanian, Karl
AU  - Le Poul, Emmanuel
AU  - Blanpain, Cédric
AU  - Percherancier, Yann
AU  - Staropoli, Isabelle
AU  - Vassart, Gilbert
AU  - Oppermann, Martin
AU  - Parmentier, Marc
AU  - Bachelerie, Françoise
TI  - Mutation of the DRY Motif Reveals Different Structural Requirements for the CC Chemokine Receptor 5-Mediated Signaling and Receptor Endocytosis
AID  - 10.1124/mol.104.009779
DP  - 2005 Jun 01
TA  - Molecular Pharmacology
PG  - 1966--1976
VI  - 67
IP  - 6
4099  - http://molpharm.aspetjournals.org/content/67/6/1966.short
4100  - http://molpharm.aspetjournals.org/content/67/6/1966.full
SO  - Mol Pharmacol2005 Jun 01; 67
AB  - CC chemokine receptor 5 (CCR5) is a G protein-coupled receptor that governs migration of leukocytes and serves as a coreceptor for the R5 tropic strains of human immunodeficiency virus (HIV). CCR5-mediated signaling in response to CC chemokines relies on G protein activation. Desensitization, which rapidly turns off G protein-dependent signaling, involves phosphorylation of CCR5 that promotes interaction of the receptor with β-arrestins for endocytosis. Whether coupling to G proteins, desensitization, and endocytosis of CCR5 require the same structural determinants remains a matter of investigation. Here, we show that CCR5 displayed agonist-independent coupling to G proteins. This constitutive activity of the receptor was abrogated by TAK779 (N,N-dimethyl-N-[4-[[[2-(4-methylphenyl)-6,7-dihydro-5H-benzocyclohepten-8-yl]carbonyl]amino]benzyl]tetrahydro-2H-pyran-4-aminium chloride), a nonpeptidic CCR5 ligand that inhibits HIV infection and was found to depend on the integrity of the Asp-Arg-Tyr (DRY) motif. Changing Arg-126 by the neutral residue Asn (R126N-CCR5 mutant) abolished CCR5-mediated activation of G proteins, either constitutively or in response to agonists. In contrast, R126N-CCR5 not only retained agonist-promoted phosphorylation and β-arrestin-dependent endocytosis but also displayed a higher basal phosphorylation than wild-type CCR5. Expression of β-arrestin in R126N-CCR5-expressing cells resulted in receptor down-regulation, thereby suggesting that R126N-CCR5 spontaneously interacts with β-arrestins. However, although expression of β-arrestin favored wild-type CCR5-mediated chemotaxis, it failed to promote migration of cells expressing R126N-CCR5. Overall, these data indicate that structural requirements for CCR5-mediated activation of G proteins, albeit not involved in receptor desensitization and internalization, are needed for β-arrestin-mediated chemotaxis. These results have implications for how distinct biological responses of CCR5 might rely on a different set of receptor conformations.