Granulocyte chemotactic protein 2 acts via both IL-8 receptors, CXCR1 and CXCR2.
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.
Wolf
M
M
Theodor Kocher Institute, University of Bern, Switzerland. marlene.wolf@tki.unibe.ch
Delgado
M B
MB
Jones
S A
SA
Dewald
B
B
Clark-Lewis
I
I
Baggiolini
M
M
D000595:Amino Acid Sequence; D015703:Antigens, CD / Q000187:drug effects*; D054360:Chemokine CXCL1; D054365:Chemokine CXCL5; D054427:Chemokine CXCL6; D018925:Chemokines / Q000494:pharmacology*; D019743:Chemokines, CXC; D002630:Chemotactic Factors / Q000494:pharmacology; D002634:Chemotaxis, Leukocyte / Q000187:drug effects; D006133:Growth Substances / Q000494:pharmacology; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D016209:Interleukin-8 / Q000031:analogs & derivatives / Q000494:pharmacology; D019169:Jurkat Cells; D008969:Molecular Sequence Data; D010196:Pancreatic Elastase / Q000378:metabolism; D011485:Protein Binding; D019707:Receptors, Chemokine / Q000187:drug effects*; D018123:Receptors, Interleukin / Q000187:drug effects*; D023062:Receptors, Interleukin-8A; D023063:Receptors, Interleukin-8B; D011993:Recombinant Fusion Proteins / Q000187:drug effects; D013329:Structure-Activity Relationship; D014162:Transfection
D015703:Antigens, CD; C475829:CXCL1 protein, human; C486263:CXCL5 protein, human; C515503:CXCL6 protein, human; D054360:Chemokine CXCL1; D054365:Chemokine CXCL5; D054427:Chemokine CXCL6; D018925:Chemokines; D019743:Chemokines, CXC; D002630:Chemotactic Factors; D006133:Growth Substances; D036341:Intercellular Signaling Peptides and Proteins; D016209:Interleukin-8; D019707:Receptors, Chemokine; D018123:Receptors, Interleukin; D023062:Receptors, Interleukin-8A; D023063:Receptors, Interleukin-8B; D011993:Recombinant Fusion Proteins; D010196:Pancreatic Elastase