F2L, a Peptide Derived from Heme-Binding Protein, Chemoattracts Mouse Neutrophils by Specifically Activating Fpr2, the Low-Affinity N-Formylpeptide Receptor

Abstract

F2L (formylpeptide receptor (FPR)-like (FPRL)-2 ligand), a highly conserved acetylated peptide derived from the amino-terminal cleavage of heme-binding protein, is a potent chemoattractant for human monocytes and dendritic cells, and inhibits LPS-induced human dendritic cell maturation. We recently reported that F2L is able to activate the human receptors FPRL-1 and FPRL2, two members of the FPR family, with highest selectivity and affinity for FPRL2. To facilitate delineation of mechanisms of F2L action in vivo, we have now attempted to define its mouse receptors. This is complicated by the nonequivalence of the human and mouse FPR gene families (three vs at least eight members, respectively). When cell lines were transfected with plasmids encoding the eight mouse receptors, only the one expressing the receptor Fpr2 responded to F2L (EC50 ∼400 nM for both human and mouse F2L in both calcium flux and cAMP inhibition assays). This value is similar to F2L potency at human FPRL1. Consistent with this, mouse neutrophils, which like macrophages and dendritic cells express Fpr2, responded to human and mouse F2L in both calcium flux and chemotaxis assays with EC50 values similar to those found for Fpr2-expressing cell lines (∼500 nM). Moreover, neutrophils from mice genetically deficient in Fpr2 failed to respond to F2L. Thus, Fpr2 is a mouse receptor for F2L, and can be targeted for the study of F2L action in mouse models.

Formyl Peptide Receptor-Like 2 Is Expressed and Functional in Plasmacytoid Dendritic Cells, Tissue-Specific Macrophage Subpopulations, and Eosinophils

“…Mouse Fpr2 is expressed by neutrophils, DCs, and microglial cells, and its transcripts are detected at high levels in spleen and lung (23,24). After the testing of the whole set of mouse FPR-related receptors, Gao et al (25) identified Fpr2 as the only mouse receptor responding to F2L. Indeed, mouse neutrophils, which express Fpr2, respond to human F2L (hF2L) and mouse F2L (mF2L) in both calcium flux and chemotaxis assays.…”

“…The ability of mF2L to promote chemotaxis of neutrophils through Fpr2 was demonstrated previously (25). We tested further the capacity of mF2L to induce recruitment of DCs and macrophages, which also express the receptor.…”

“…We have identified recently the mouse receptor Fpr2, encoded by Fpr-rs2, as a partial functional homolog of human FPRL2, and demonstrated that mouse neutrophils expressing Fpr2 responded to mF2L in a chemotaxis assay (25). With the aim of comparing mouse Fpr2 expression with that of human FPRL2, we tested the presence of Fpr2 transcripts in various mouse leukocyte populations, using GAPDH as a housekeeping control gene.…”

Cathepsin G-regulated Release of Formyl Peptide Receptor Agonists Modulate Neutrophil Effector Functions

“…Boc2 inhibition was relieved by the addition of either the Fpr1 agonist N-formylmethionyl-leucyl-phenylalanine (fMLF) (19) or the Fpr2 agonist F2L (Fig. 5C) (22). Furthermore, low micromolar concentrations of fMLF and F2L are able to induce CXCL2 release by IC-stimulated CG-deficient neutrophils (Fig.…”

F2L, a peptide derived from heme‐binding protein, inhibits LL‐37‐induced cell proliferation and tube formation in human umbilical vein endothelial cells

“…FPRL1 Since F2L has been reported to induce the chemotactic migration of mouse neutrophils via FPR2 (mouse counterpart of human FPRL1) [15], we tested whether F2L stimulates the chemotactic migration of HUVECs via FPRL1, with the aid of an FPRL1-selective antagonist (WRW 4 ) [18]. The F2L-induced HUVEC chemotaxis was completely inhibited by WRW 4 (Fig.…”