P2Y2 RECEPTOR PEPDUCINS HIJACK AND ACTIVATE THE FORMYL PEPTIDE RECEPTOR 2 IN HUMAN NEUTROPHILS

Abstract

Neutrophils are the most abundant phagocytic cell type and have a critical role in the innate immune system. They are attracted to the site of infection/inflammation through a number of surface expressing chemoattractant G-protein coupled receptors (GPCRs). Activation of neutrophil GPCRs mediates not only directional migration, but also triggers the release of reactive oxygen species and granule stored enzymes. The formyl peptide receptor 1 (FPR1), displaying high binding affinity for the “danger signal” formyl peptides derived from bacteria or damaged mitochondria, was the first chemoattractant GPCRs cloned and has therefore served as a model receptor for our understanding of neutrophil physiology. In addition to FPR1, neutrophils express also the closely related formyl peptide receptor 2 (FPR2) and the danger signaling ATP recognition receptor (P2Y2-R). All GPCRs share a similar seven transmembrane helical structure in which the extracellular domains are involved in ligand binding whereas the intracellular parts are engaged in G-protein coupling and signaling transduction. Recent research has proposed a group of cell penetrating molecules, so called pepducins that can modulate GPCR signaling from the inside. Pepducins are lipopeptides derived from one of the intracellular lopes of a GPCR, they are supposed to allosterically activate or inhibit the receptor from it is derived. In this study, we investigated the ATP receptor signaling by applying pepducins from the P2Y2 receptor. Our data show that these pepducins do not target their cognate receptor as the currently “pepducin model” proposed and instead activate FPR2. This “model” has also been challenged by the recent findings from pepducins from FPR1 and β2-adrenergic receptor