CDB15:0000212 CCL1 — CCR8

ABSTRACT: We have previously shown that the CC-chemokine 1-309 (CCL1) protects mouse thymic lymphomas against corticoid-induced apoptosis. Here, we analyzed the signal transduction pathways involved in this activity on BW5147 lymphoma. Inhibition of the CCL1 activity by pertussis toxin suggested the involvement of a G protein-coupled chemokine receptor. The role of CCR8 was supported by the observation that vMIP-I, another CCR8-ligand identified from the genome of a T cell transforming herpes virus, shared CCL1 anti-apoptotic activity. In addition to CCR8, BW5147 cells also expressed the CXCR4 receptor but its ligand, SDF-1 (CXCL12) showed only a modest anti-apoptotic activity. Other chemokines acting on CCR2, CCR4 and CCR5 failed to protect against apoptosis and to induce BW5147 chemotaxis, suggesting that these receptors were not functionally expressed. By contrast, both CCL1 and vMIP-I up-regulated ERK1/2 MAPK phosphorylation in BW5147 cells. Further analysis demonstrated that CCL1 activates the MAPK pathway in CCR8-transfected CHO cells. The implication of this pathway was confirmed by the fact that PD98059, an inhibitor of MEK kinases, as well as a dominant negative isoform of the M-RAS protein specifically blocked the anti-apoptotic activity of CCL1.

ABSTRACT: In this study, we report the first example of a nonpeptide chemokine receptor agonist, 2-{2-[4-(3-phenoxybenzyl)piperazin-1-yl]ethoxy}ethanol (ZK 756326), for the CC chemokine receptor CCR8. ZK 756326 inhibited the binding of the CCR8 ligand I-309 (CCL1), with an IC(50) value of 1.8 muM. Furthermore, ZK 756326 was a full agonist of CCR8, dose-responsively eliciting an increase in intracellular calcium and cross-desensitizing the response of the receptor to CCL1. In addition, ZK 756326 stimulated extracellular acidification in cells expressing human CCR8. The ability of ZK 756326 to induce a response was receptor-specific and mediated through Galpha(i), because it could be blocked by treatment with pertussis toxin. The CCR8 agonist activated cells expressing murine CCR8, eliciting their chemotaxis and inducing phosphorylation of extracellular signal-regulated kinase ERK1/2. Like CCL1, ZK 756326 inhibited human immunodeficiency virus (HIV) fusion of cells expressing CD4 and CCR8. Finally, unlike mCCL1, ZK 756326 bound to and activated a form of mCCR8 that was mutated to eliminate O-linked sulfation at tyrosines 14 and 15. Therefore, ZK 756326 is most probably not binding in the same manner as CCL1 but can activate the switch mechanism involved in transducing signaling events. In summary, we have identified a nonpeptide agonist of CCR8. This compound may be useful in evaluating the physiological role of CCR8 in HIV infection, as well as in the general study of CCR8 biology without the constraints inherent to the use of protein agonists such as its natural ligand.

ABSTRACT: The nucleotide sequence for a putative chemokine receptor, termed TER1, ChemR1, or CKR-L1, was recently obtained by a polymerase chain reaction-based cloning technique. It encodes a protein of 355 amino acids that shows 32-45% sequence identity with human chemokine receptors. The gene was localized on human chromosome 3p21-24, the site for the genes for the five known CC chemokine receptors, suggesting that the natural ligand may be a CC chemokine. We have stably expressed this receptor in murine pre-B cells 300-19 and have tested their responsiveness to 20 human chemokines and some other potential agonists. The CC chemokine I-309 was the only agonist that selectively induced intracellular Ca2+ mobilization and chemotaxis in receptor-transfected 300-19 cells. Stromal cell-derived factor 1, which binds to murine CXCR4 expressed in parental as well as transfected 300-19 cells, served as positive control in the functional screening. The interaction of I-309 with TER1 was of high affinity as shown by 125I-I-309 binding (Kd of 1.2 nM) and transient [Ca2+]i changes at subnanomolar concentrations of agonist. Migration responses in receptor-transfected 300-19 cells was typically bimodal with maximal activity at 10 nM of I-309. These data demonstrate that TER1 (ChemR1 or CKR-L1) is the receptor for I-309, and we propose to call this receptor CCR8 in agreement with the current nomenclature for chemokine receptors. The expression of CCR8 in blood leukocytes and lymphocytes was analyzed by Northern blot. No transcripts were found in RNA from freshly isolated blood neutrophils, monocytes, cultured macrophages, and phytohemagglutinin-stimulated T lymphocytes, and a faint hybridization signal corresponding to the RNA species of 4 kb was obtained only with RNA from interleukin-2-treated T lymphocytes. CCR8 is unusual for its selectivity for a single chemokine, previously shown only for CXCR1 and CXCR4, which bind interleukin-8 and stromal cell-derived factor 1, respectively. Identification of the receptor for I-309 represents a significant progress in determining the function of I-309 in inflammation and disease.