Association of the N-formyl-Met-Leu-Phe receptor in human neutrophils with a GTP-binding protein sensitive to pertussis toxin.

Abstract

Pertussis toxin inhibits the N-formyl-MetLeu-Phe (fMet-Leu-Phe) mediated human neutrophil functions of enzyme release, superoxide generation, aggregation, and chemotaxis. As pertussis toxin modifies the GTP binding receptor-regulatory protein "N1," the association of the fMetLeu-Phe receptor with such a protein was further examined in purified neutrophil plasma membranes. Both fMet-Leu-Phemediated guanine nucleotide exchange and nucleotide-mediated regulation of the fMet-Leu-Phe receptor are inhibited by pertussis toxin. In addition, membrane pretreatment with pertussis toxin abolishes the fMet-Leu-Phe-mediated inhibition of adenylate cyclase. Actions of pertussis toxin are due to the ADP-ribosylation of a single subunit at 41 kDa in the neutrophil plasma membrane, which comigrates on NaDodSO4 gels with the N. GTP-binding protein in the platelet plasma membrane. Our results suggest that (i) the fMet-Leu-Phe receptor is associated with a N. GTP regulatory protein, and (it) a fMetLeu-Phe-N; complex is important in the control of several neutrophil functions, probably involving multiple transduction systems, including adenylate cyclase.

The dynamics of exocytosis in human neutrophils.

“…The involvement of a guanine nucleotide-binding protein (G protein) in neutrophil activation has been implicated from the inhibitory effect of pertussis toxin on the response stimulated by fMet-Leu-Phe (18,30). This G protein could have been directly activated by GTPTS in our experiments.…”

Role of G protein-coupled receptors in inflammation

“…Evidence that these "classic chemoattractants" act on GPCRs first came from the observation that pertussis toxin (PTX) could alter the binding affinity of chemotactic formyl peptides [5] , a characteristic feature of certain GPCR ligands [6] . Working independently, two laboratories reported that PTX could block formyl peptide (eg, fMet-Leu-Phe, fMLF)-induced neutrophil functions through ADP-ribosylation of the Gi class of heterotrimeric G proteins [7,8] . These early studies demonstrate that the chemotactic peptide receptor functionally couples to a heterotrimeric G protein that is a substrate for ADP-ribosylation by PTX.…”

Redox signaling mediated by the gut microbiota

“…In a pathological context such as tissue necrosis (not apoptosis), cellular contents are released extracellularly and can be perceived by other cells and phagocytes as "danger associated molecular patterns" or DAMPS [34]. Once the agonist binds, FPRs are phosphorylated and glycosylated, which initiates interaction with pertussis toxin-sensitive Gi proteins [35][36][37][38]. Ensuring cell signaling cascades involves MAPK and phosphatidylinositol 3-kinase (PI3K) pathway activation, which together with small GTPases initiate phagocytic functions such as stimulation of actin dynamics and chemotaxis, and the activation of ROS generation by NADPH oxidase enzyme (Nox2) in a process known as the respiratory burst [39][40][41].…”