Granulocyte chemotactic protein 2 acts via both IL- 8 receptors, CXCR1 and CXCR2

Abstract

Interleukin-8 (IL-8) acts on human neutrophils via two receptors, CXCR1 and CXCR2. It shares CXCR2 with all neutrophil-activating chemokines, which like IL-8 have a conserved Glu-Leu-Arg (ELR) N-terminal motif, but is generally considered to be the only relevant agonist for CXCR1. IL-8 has a basic residue at the sixth position after the second cysteine, which was suggested to contribute to CXCR1 specificity. Among the other ELR chemokines, only granulocyte chemotactic protein 2 (GCP-2) has such a basic determinant. Using Jurkat cells that stably express either CXCR1 or CXCR2, we studied receptor activation by IL-8, GCP-2 epithelial neutrophil-activating protein 2 (ENA-78) (which shares 77% identical amino acids with GCP-2) and growth-regulated oncogene alpha (GRO alpha). At 10 nM and higher concentrations, GCP-2 and IL-8 induced significant activation of CXCR1-expressing cells, but no activity was found with GRO alpha and ENA-78. As expected, however, all four chemokines had similar activities on CXCR2-expressing cells. A variant of GCP-2 in which the basic residue, Arg20, was replaced by a glycine was synthesized. This derivative was ineffective on CXCR1, but was as active as wild-type GCP-2 in CXCR2-expressing cells. GCP-2 displaced radiolabeled IL-8 from both receptors with low affinity, and in this respect resembled ENA-78 and GRO alpha. Our data show that GCP-2 acts via both IL-8 receptors and thus appears to be functionally more similar to IL-8 than to the other ELR chemokines. Activation of CXCR1 appears to depend significantly on the presence of a basic binding determinant close to the second cysteine.

Rab11-Family Interacting Protein 2 and Myosin Vb Are Required for CXCR2 Recycling and Receptor-mediated Chemotaxis

“…Like other members of the chemokine receptor family, CXCR2 can stimulate cell migration in response to gradient concentrations of ligand (Loetscher et al, 1994;Wolf et al, 1998;Wuyts et al, 1998;Feniger-Barish et al, 2000). Previous studies have demonstrated that vesicle recycling is necessary for cell migration (Bretscher 1992;Hopkins et al, 1994).…”

The CXC Chemokine GCP-2/CXCL6 Is Predominantly Induced in Mesenchymal Cells by Interleukin-1β and Is Down-Regulated by Interferon-γ: Comparison with Interleukin-8/CXCL8

“…Furthermore, the secreted IL-8 levels were in most cases at least 10 times higher compared with those of GCP-2. IL-8 and GCP-2 are the only ELR ϩ CXC chemokines that chemoattract and activate neutrophils by binding to both CXCR1 and CXCR2, whereas the other ELR ϩ CXC chemokines only signal through CXCR2 (Wolf et al, 1998;Wuyts et al, 1998a). However, IL-8 is more potent than GCP-2 at activating neutrophils (Proost et al, 1993).…”

“…Human IL-8 and GCP-2 are the only ELR ϩ CXC chemokines that recognize both the receptors CXCR1 and CXCR2 (Murphy et al, 2000;Wolf et al, 1998;Wuyts et al, 1998a). IL-8 is the first identified member of this chemokine subgroup and is the most potent neutrophil chemotactic and activating protein (Wuyts et al, 1998b).…”

Angiogenic Effects of Interleukin 8 (CXCL8) in Human Intestinal Microvascular Endothelial Cells Are Mediated by CXCR2

“…The chemokine receptor CXCR2 promiscuously binds all known angiogenic ELR ϩ CXC chemokines, including IL-8, the growth-regulated oncogene family members (GRO-␣, -␤, and -␥), NAP-2, GCP-2, and ENA-78 with high affinity (29,30). In contrast, CXCR1 specifically binds only IL-8 and GCP-2 (30,31). Both CXCR1 and CXCR2 are members of the seven-transmembrane domain rhodopsin-like G protein-coupled receptor superfamily and share 78% amino acid sequence homology (32).…”