title: Annexin A1 interaction with the FPR2/ALX receptor: identification of distinct domains and downstream associated signaling.
abstract: Understanding how proresolving agonists selectively activate FPR2/ALX is a crucial step in the clarification of proresolution molecular networks that can be harnessed for the design of novel therapeutics for inflammatory disease. FPR2/ALX, a G protein-coupled receptor belonging to the formyl peptide receptor (FPR) family, conveys the biological functions of a variety of ligands, including the proresolution mediators annexin A1 (AnxA1) and lipoxin A(4), as well as the activating and proinflammatory protein serum amyloid A. FPR2/ALX is the focus of intense screening for novel anti-inflammatory therapeutics, and the small molecule compound 43 was identified as a receptor ligand. Here, we used chimeric FPR1 and FPR2/ALX clones (stably transfected in HEK293 cells) to identify the N-terminal region and extracellular loop II as the FPR2/ALX domain required for AnxA1-mediated signaling. Genomic responses were also assessed with domain-specific effects emerging, so the N-terminal region is required for AnxA1 induction of JAG1 and JAM3, whereas it is dispensable for modulation of SGPP2. By comparison, serum amyloid A non-genomic responses were reliant on extracellular loops I and II, whereas the small molecule compound 43 activated extracellular loop I with downstream signaling dependent on transmembrane region II. In desensitization experiments, the N-terminal region was dispensable for AnxA1-induced FPR2/ALX down-regulation in both the homologous and heterologous desensitization modes.
authors.affiliation: William Harvey Research Institute, Barts and The London School of Medicine, Queen Mary University of London, London EC1M 6BQ, United Kingdom.
authors.forename: Stefania
authors.initials: S
authors.lastname: Bena
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Brancaleone
authors.forename: Ji Ming
authors.initials: JM
authors.lastname: Wang
authors.forename: Mauro
authors.initials: M
authors.lastname: Perretti
authors.forename: Roderick J
authors.initials: RJ
authors.lastname: Flower
mesh_terms: D017305:Annexin A1 / Q000737:chemistry* / Q000378:metabolism*; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D005434:Flow Cytometry; D057809:HEK293 Cells; D006801:Humans; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D017434:Protein Structure, Tertiary; D044042:Receptors, Formyl Peptide / Q000737:chemistry / Q000378:metabolism*; D044067:Receptors, Lipoxin / Q000737:chemistry / Q000378:metabolism*; D000685:Serum Amyloid A Protein / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D017305:Annexin A1; C105101:FPR2 protein, human; D044042:Receptors, Formyl Peptide; D044067:Receptors, Lipoxin; D000685:Serum Amyloid A Protein; D002118:Calcium