The chemokine receptor CCX-CKR mediates effective scavenging of CCL19 in vitro

Comerford, I., Milasta, S., Morrow, V., Milligan, G. and Nibbs, R. (2006) The chemokine receptor CCX-CKR mediates effective scavenging of CCL19 in vitro. European Journal of Immunology, 36(7), pp. 1904-1916. (doi: 10.1002/eji.200535716)

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Abstract

The chemokines CCL19, CCL21 and CCL25, by signalling through the receptors CCR7 or CCR9, play critical roles in leukocyte homing. They also bind another heptahelical surface protein, CCX-CKR. CCX-CKR cannot couple to typical chemokine receptor signalling pathways or mediate chemotaxis, and its function remains unclear. We have proposed that it controls chemokine bioavailability. Here, using transfected HEK293 cells, we have shown that both CCX-CKR and CCR7 mediate rapid CCL19 internalisation upon initial chemokine exposure. However, internalised CCL19 was more efficiently retained and degraded after uptake via CCX-CKR. More importantly, CCR7 rapidly became refractory for CCL19 uptake, but the sequestration activity of CCX-CKR was enhanced. These properties endowed CCX-CKR with an impressive ability to mediate progressive sequestration and degradation of large quantities of CCL19, and conversely, prevented CCR7-expressing cells from extensively altering their chemokine environment. These differences may be linked to the routes of endocytosis used by these receptors. CCX-CKR, unlike CCR7, was not critically dependent on β-arrestins or clathrin-coated pits. However, over-expression of caveolin-1, which stabilises caveolae, blocked CCL19 uptake by CCX-CKR while having no impact on other chemokine receptors, including CCR7. These data predict that CCX-CKR scavenges extracellular chemokines in vivo to modify responses through CCR7.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Nibbs, Professor Rob and Milligan, Professor Graeme and Morrow, Dr Valerie
Authors: Comerford, I., Milasta, S., Morrow, V., Milligan, G., and Nibbs, R.
College/School:College of Medical Veterinary and Life Sciences > Institute of Infection Immunity and Inflammation
Journal Name:European Journal of Immunology
Journal Abbr.:Eur. J. Immunol.
ISSN:0014-2980
ISSN (Online):1521-4141
Published Online:22 June 2006
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