Identification and characterization of an endogenous chemotactic ligand specific for FPRL2

Abstract

Chemotaxis of dendritic cells (DCs) and monocytes is a key step in the initiation of an adequate immune response. Formyl peptide receptor (FPR) and FPR-like receptor (FPRL)1, two G protein–coupled receptors belonging to the FPR family, play an essential role in host defense mechanisms against bacterial infection and in the regulation of inflammatory reactions. FPRL2, the third member of this structural family of chemoattractant receptors, is characterized by its specific expression on monocytes and DCs. Here, we present the isolation from a spleen extract and the functional characterization of F2L, a novel chemoattractant peptide acting specifically through FPRL2. F2L is an acetylated amino-terminal peptide derived from the cleavage of the human heme-binding protein, an intracellular tetrapyrolle-binding protein. The peptide binds and activates FPRL2 in the low nanomolar range, which triggers intracellular calcium release, inhibition of cAMP accumulation, and phosphorylation of extracellular signal–regulated kinase 1/2 mitogen-activated protein kinases through the Gi class of heterotrimeric G proteins. When tested on monocytes and monocyte-derived DCs, F2L promotes calcium mobilization and chemotaxis. Therefore, F2L appears as a new natural chemoattractant peptide for DCs and monocytes, and the first potent and specific agonist of FPRL2.

The Synthetic Peptide Trp-Lys-Tyr-Met-Val-D-Met Inhibits Human Monocyte-Derived Dendritic Cell Maturation via Formyl Peptide Receptor and Formyl Peptide Receptor-Like 2

“…8B, treatment of MoDCs with Hp(2-20) (50 M) plus LPS (100 ng/ml) inhibited IL-12 production by DCs, suggesting that LPS-induced MoDC maturation is inhibited by Hp(2-20) treatment, and that the activation of FPRL2 by Hp(2-20) inhibits LPS-induced MoDC maturation. More recently, the FPRL2-selective peptide ligand, F2L, was reported to be a natural DC chemoattractant (20). We also found that treatment with F2L (100 nM) plus LPS (100 ng/ml) significantly inhibited IL-12 production by LPS (Fig.…”

“…(19) was a gift from Dr. K. S. Hahm (Chosun University, Gwangju, Korea). Acetylated F2L (Ac-MLGMIKNS LFGSVETWPWQVL) (20) was synthesized by Anygen. PE-conjugated mAb against CD86, FITC-conjugated mAb against HLA-DR, and human recombinant TNF-␣ were from BD Pharmingen.…”

Human mitochondria-derivedN-formylated peptides are novel agonists equally active on FPR and FPRL1, whileListeria monocytogenes-derived peptides preferentially activate FPR

“…The first ligand shown to bind with high affinity (low nanomolar range) to this receptor was lipoxin A4 (LXA4), an anti-inflammatory lipid mediator [10]. Recently, FPRL1 has emerged as a promiscuous receptor, also activated by the pathogenderived peptide Hp (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) from Helicobacter pylori, by host-derived proteins and peptides such as Ac1-25 from annexin 1, cathelicidin LL37, a fragment of the urokinase receptor, the serum amyloid A, the amyloid b peptide (Ab42), the prion protein fragment PrP(106-126), the neuroprotective peptide humanin, and by different synthetic peptides including the hexapeptide Trp-LysTyr-Met-Val-D-Met-NH 2 (WKYMVm) [11,12]. FPRL2 does not respond to fMLF [13], but instead is activated by some non-formylated chemotactic peptides identified as agonists for FPRL1 [14,15].…”

“…FPRL2 does not respond to fMLF [13], but instead is activated by some non-formylated chemotactic peptides identified as agonists for FPRL1 [14,15]. Recently, an acetylated Nterminal peptide derived from the human heme-binding protein has been identified as a ligand specific for FPRL2 [16].…”

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

“…Furthermore, it is known that apoptotic cells release chemotactic factors to attract phagocytes. F2L act as a chemoattractant for monocytes, and dendritic cells that would induce cellular responses against apoptotic cells [14]. Interestingly, we also found that F2L induced the chemotactic migration of endothelial cells, indicat- After an 18 h incubation period, we assessed the tube formation by obtaining photographs from an inverted phase contrast microscope image (50·) (A).…”