The human N-formylpeptide receptor. Characterization of two cDNA isolates and evidence for a new subfamily of G-protein-coupled receptors

Abstract

Two variants of the human N-formylpeptide chemoattractant receptor have been isolated from a CDM8 expression library prepared from mRNA of human myeloid HL-60 cells differentiated to the granulocyte phenotype with Bt2cAMP. Both recombinant receptors, fMLP-R26 and fMLP-R98, are 350 amino acids long (Mr 38,420); they differ from each other by two residue changes at positions 101 and 346 and by significant differences in the 5' and 3' untranslated regions. Both clones were able to transfer to COS-7 cells the capacity to specifically bind a new and highly efficient hydrophilic derivative of N-formyl-Met-Leu-Phe-Lys, referred to as fMLPK-Pep12. Photolabeling experiments revealed that the glycosylated form of the fMLP receptor in COS cells has a molecular weight (Mr 50,000-70,000) similar to that observed for the native receptor in differentiated HL-60 cells. Northern blot analysis revealed a major transcript of 1.6-1.7 kb and two minor hybridization signals of 2.3 and 3.1 kb, suggesting a related family of receptors. The complex hybridization pattern obtained with restricted genomic DNA was consistent with either two genes encoding fMLP receptor isoforms or a single gene with at least one intron in the coding sequence. Sequence comparison established that the fMLP receptor belongs to the G-protein-coupled receptor superfamily. The structural similarities observed with RDC1, a receptor isolated from a dog thyroid cDNA library, which shares weak homologies with other members of the family, suggests that the fMLP receptor is representative of a new subfamily.

Evaluation of human leukocyte N-formylpeptide receptor (FPR1) SNPs in aggressive periodontitis patients

“…Sequence alignment of all available cDNAs and ESTs for the three genes with this BAC contig indicated the presence of two exons for each gene. [14][15][16][17] Although reports that FPR1 and FPRL-1 have three exons were not verified by EST or cDNA data, FPR1 and FPRL-1 were each found to have a single exon ORF as previously reported. 16 The sizes of the exons and intron are given for FPR1 in Figure 1B.…”

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

“…Since the identification and molecular cloning of the N-formyl peptide receptor [2] and its homologues [1,3] a decade ago, their pathophysiological role has broaded beyond host resistance against exogenous pathogens. In particular, the usage of FPRL1 and FPRL2 by hostderived agonists suggests that these receptors may play a crucial role in the regulation of the inflammatory processes associated with tissue damage and neurodegenerative diseases.…”

“…Both cell lines gave an intracellular calcium response peaking at 400-600 nM after stimulation with 1 lM of the hexapeptide WKYMVm. The cDNA encoding FPR (clone FPR26) [2] was cloned into the pEFneo plasmid cleaved by XbaI. Transfection of HL-60 cells was performed as previously described [38].…”

“…Like other chemoattractants, including the activated complement component 5 (C5a), platelet-activating factor (PAF), leukotriene B4 (LTB4) and a superfamily of chemokines, they activate seven-transmembranedomain Gi protein-coupled receptors (GPCR) [1][2][3] present on phagocytic cells and other cell types. The binding of chemoattractants to their receptors on phagocytic cells causes calcium mobilization, activation of the NADPH oxidase, and the release of the content of granules.…”

“…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].…”