Multiple roles for the C-terminal tail of the chemokine scavenger D6

McCulloch, C., Morrow, V., Milasta, S., Comerford, I., Milligan, G. , Graham, G. , Isaacs, N. and Nibbs, R. (2008) Multiple roles for the C-terminal tail of the chemokine scavenger D6. Journal of Biological Chemistry, 283(12), pp. 7972-7982. (doi: 10.1074/jbc.M710128200)

Abstract

D6 is a heptahelical receptor that suppresses inflammation and tumorigenesis by scavenging extracellular pro-inflammatory CC chemokines. Previous studies suggested this is dependent on constitutive trafficking of stable D6 protein to and from the cell surface via recycling endosomes. By internalizing chemokine each time it transits the cell surface, D6 can, over time, remove large quantities of these inflammatory mediators. We have investigated the role of the conserved 58-amino acid C terminus of human D6, which, unlike the rest of the protein, shows no clear homology to other heptahelical receptors. We show that, in human HEK293 cells, a serine cluster in this region controls the constitutive phosphorylation, high stability, and intracellular trafficking itinerary of the receptor and drives green fluorescent protein-tagged beta-arrestins to membranes at, and near, the cell surface. Unexpectedly, however, these properties, and the last 44 amino acids of the C terminus, are dispensable for D6 internalization and effective scavenging of the chemokine CCL3. Even in the absence of the last 58 amino acids, D6 still initially internalizes CCL3 but, surprisingly, exposure to ligand inhibits subsequent CCL3 uptake by this mutant. Progressive scavenging is therefore abrogated. We conclude that the heptahelical body of D6 on its own can engage the endocytotic machinery of HEK293 cells but that the C terminus is indispensable for scavenging because it prevents initial chemokine engagement of D6 from inhibiting subsequent chemokine uptake.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Nibbs, Professor Rob and Milligan, Professor Graeme and Morrow, Dr Valerie and Isaacs, Professor Neil and McCulloch, Mrs Clare and Graham, Professor Gerard
• Authors: McCulloch, C., Morrow, V., Milasta, S., Comerford, I., Milligan, G., Graham, G., Isaacs, N., and Nibbs, R.
• College/School: College of Medical Veterinary and Life Sciences > School of Infection & Immunity; College of Medical Veterinary and Life Sciences > School of Psychology & Neuroscience; College of Science and Engineering > School of Chemistry
• Journal Name: Journal of Biological Chemistry
• Journal Abbr.: J Biol Chem.
• Publisher: American Society for Biochemistry and Molecular Biology, Inc.
• ISSN: 0021-9258
• ISSN (Online): 1083-351X