1. ¹AstraZeneca R&D Montréal, 7171 Frederick-Banting, Ville Saint-Laurent, Québec, Canada, H4S 1Z9
2. ²AstraZeneca R&D Charnwood, Bakewell Road, Loughborough, Leicester LE11 5RH, U.K.

Correspondence: Aram Elagoz, AstraZeneca R&D Montréal, 7171 Frederick-Banting, Ville Saint-Laurent, Québec, Canada, H4S 1Z9. E-mail: aram.elagoz@astrazeneca.com

³Contributed equally to this study

Received 17 July 2003; Revised 18 September 2003; Accepted 22 October 2003; Published online 8 December 2003.

Abstract

1.  Human formyl peptide-receptor-like-1 (FPRL-1) is a promiscuous G protein-coupled receptor (GPCR), and belongs to a chemoattractant receptor family protein. This receptor has been reported to interact with various host-derived peptides and lipids involved in inflammatory responses. We described here, a novel role for FPRL-1 as a high-affinity -chemokine receptor for an N-terminally truncated form of the CK8 (CCL23/MPIF-1) splice variant CK8-1 (22–137 aa).
2.  RT-PCR analysis of mRNA derived from human tissues and cells revealed a predominant expression of FPRL-1 in inflammatory cells, particularly in neutrophils.
3.  Intracellular calcium mobilisation assay, used as screening tool, in recombinant Chinese hamster ovary (CHO-K1) and human embryonic kidney (HEK293s) cells coexpressing FPRL-1 and G₁₆, demonstrated FPRL-1 is a functional high-affinity receptor for CK8-1 (46–137 aa, sCK8-1), with pEC₅₀ values of 9.13 and 8.85, respectively.
4.  The FPRL-1 activation in CHO-K1 cells is mediated by G_i/G_o proteins, as assessed by pertussis toxin sensitivity and inhibition of forskolin-induced cyclic AMP accumulation.
5.  Binding experiments were performed with a radio-iodinated synthetic peptide, [^125-I]-WKYMVm, a known potent FPRL-1 agonist. CHO-K1 cell membranes expressing FPRL-1 bound [^125-I]-WKYMVm with a K_d value of 9.34. Many known FPRL-1 agonists were tested and sCK8-1 was the most effective nonsynthetic ligand in displacing the radiolabelled agonist, with a pIC₅₀ of 7.97.
6.  The functional significance of sCK8-1 interaction with FPRL-1 was further demonstrated by the activation of polymorphonuclear leukocytes (PMNs) calcium mobilisation and chemotaxis. These interactions were shown to be via FPRL-1 by specific blockade of PMNs activation in the presence of an FPRL-1 antibody.