FMLP Actions and its Binding Sites in Isolated Human Coronary Arteries

Lee

The Journal of Immunology

et al. 2006

Although the neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) has been implicated in the regulation of several immune responses, its target receptors and signaling mechanisms have yet to be fully elucidated in immune cells. In this study, we found that PACAP27, but not PACAP38, specifically stimulated intracellular calcium mobilization and ERK phosphorylation in human neutrophils. Moreover, formyl peptide receptor-like 1 (FPRL1) was identified as a PACAP27 receptor, and PACAP27 was found to selectively stimulate intracellular calcium increase in FPRL1-transfected rat basophile leukocytes-2H3 cell lines. In addition, PACAP27-induced calcium increase and ERK phosphorylation were specifically inhibited by an FPRL1 antagonist, Trp-Arg-Trp-Trp-Trp-Trp (WRW4), thus supporting the notion that PACAP27 acts on FPRL1. In terms of the functional role of PACAP27, we found that the peptide stimulated CD11b surface up-regulation and neutrophil chemotactic migration, and that these responses were completely inhibited by WRW4. The interaction between PACAP27 and FPRL1 was analyzed further using truncated PACAPs and chimeric PACAPs using vasoactive intestinal peptide, and the C-terminal region of PACAP27 was found to perform a vital function in the activation of FPRL1. Taken together, our study suggests that PACAP27 activates phagocytes via FPRL1 activation, and that this results in proinflammatory behavior, involving chemotaxis and the up-regulation of CD11b.

Section: Discussionsupporting

confidence: 54%

Pituitary Adenylate Cyclase-Activating Polypeptide 27 Is a Functional Ligand for Formyl Peptide Receptor-Like 1

Lee

The Journal of Immunology

et al. 2006

Biology of Reproduction

“…Moreover, it has been reported that, in human neutrophils, the formyl peptide stimulates phospholipase A 2 either directly or through the activation of phospholipase C [17]; in addition, the peptide evokes prostanoid output not only from its conventional target, i.e., the human neutrophil [18], but also from nonmyeloid cells, such as endothelial and smooth muscle cells of coronary arteries [10]. A role for fMLP in triggering labor can therefore be hypothesized.…”

Section: Discussionmentioning

confidence: 98%

“…Several recent reports demonstrate that fMLP, a proinflammatory mediator, exerts effects independent of its action as a chemoattractant [9,10]. Moreover, it has been reported that, in human neutrophils, the formyl peptide stimulates phospholipase A 2 either directly or through the activation of phospholipase C [17]; in addition, the peptide evokes prostanoid output not only from its conventional target, i.e., the human neutrophil [18], but also from nonmyeloid cells, such as endothelial and smooth muscle cells of coronary arteries [10].…”

Section: Discussionmentioning

confidence: 99%

“…Although the fMLP receptor was originally found in polymorphonuclear and mononuclear phagocytes, its expression has been demonstrated in non-myeloid cells, such as human spermatozoa [8], hepatocytes [9], coronary arteries [10], astrocytes, and microglia [11], as well as denditric cells [12]. Moreover, a partial cDNA sequence for the fMLP receptor has been isolated from human brain [13].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Does Formyl-Methionyl-Leucyl-Phenylalanine Exert a Physiological Role in Labor in Women?1

Buzzi

Vesce

Ferretti

et al. 1999

The classical chemotactic receptor for N-formyl peptides has traditionally been associated with polymorphonuclear and mononuclear phagocytes; however, several recent reports indicate that this receptor is also expressed in non-myeloid cells. In this study we have investigated the presence of binding sites for formyl-methionyl-leucyl-phenylalanine (fMLP) in human amniotic membranes of laboring and nonlaboring women; we have also evaluated the effect of the peptide on prostaglandin E (PGE) release from the same tissue. Our results demonstrate the presence of specific, saturable binding sites for 3H-fMLP; Scatchard plot analysis suggests the presence of both high- and low-affinity binding sites in laboring amnion, while only the low-affinity receptors were evident in nonlaboring tissue. N-t-butoxycarbonyl-methionyl-leucyl-phenylalanine (Boc-MLP), a formyl peptide receptor antagonist, inhibited 3H-fMLP binding in both preparations. In addition, fMLP was able to significantly increase PGE synthesis in perifused amnion fragments from laboring and nonlaboring women. This effect was counteracted by Boc-MLP treatment. The presence of specific binding sites for fMLP in amniotic tissue and their differing expression in laboring versus nonlaboring membranes, together with the action of the peptide on PGE synthesis, all suggest a physiological role for fMLP in labor.

Immunopharmacology and Immunotoxicology

“…(11)(12)(13)(14)(15) Endogenous ligands for FPRs have not yet been clearly identified, but some likely candidates have been proposed. (16)(17)(18) Receptors of the FPR subfamily have not so far been described in species other than mammals.…”

Section: Introductionmentioning

confidence: 99%

Mutation, Selection, and Functional Repair in Formyl Peptide Receptor Genes: A View on the Selection Processes Occurring in This Gene Subfamily

Panaro¹,

Mitolo²,

Acquafredda³

et al. 2008

Formyl peptides (FPs) released by some bacteria are powerful chemoattractants and activators of granulocytes, monocytes, and macrophages, acting through the members of a subfamily of specific seven-transmembrane G-protein-coupled formyl peptide receptors (FPRs), which are expressed only in mammals. Upon stimulation, granulocytes chemotactically move towards sites of maximal FP concentration, and release different bactericidal lytic enzymes and reactive oxygen species (ROI). In some instances, such as ischemia/reperfusion, the proinflammatory mediators released by the injured tissues and the intestinal bacteria and endotoxins, which may permeate across the damaged mucosal barrier, prime the inflowing granulocytes for an enhanced ROI production, resulting in severe damage to the host tissues. In this investigation 16 representative FPR and FPR-like mRNAs were selected to study the pattern of mutation/conservation of the individual nucleotides (nt) in the coding sequences. Mutations occur in 56.7%, 46.4%, and 87.5 % of cases in the first, second, and third nt, respectively, of the coding triplets. A probabilistic analysis demonstrated a significant nonrandom linkage between mutations in the first and second nt. Furthermore, the triplets that are variously double-mutated in the first two nt code, on average, for more hydrophobic amino acids (AA) in the transmembrane segments and more hydrophilic AA in the external and intracytoplasmic segments, thus preserving the general structure of the receptor. The authors hypothesize that when in one of the first two nt a mutation leading to a nonfunctioning protein product occurred, the mutated gene was eventually eliminated; however, a second mutation occurring in the other previously unmutated Address correspondence to V. Mitolo, Immunopharmacology and Immunotoxicology Downloaded from informahealthcare.com by University of Waterloo on 11/29/14For personal use only. M.A. Panaro et al.nt may have led to a protein product that is compatible with functional activity, although mutated in one (noncritical) AA. Such double mutations effecting a "functional repair" have thus survived and are retained among the extant sequences. Moreover, the combined mutation of all three nt in coding triplets occurs with a significantly higher than random frequency and this finding may be interpreted in a similar way.