title: Reactivation of formyl peptide receptors triggers the neutrophil NADPH-oxidase but not a transient rise in intracellular calcium.
abstract: In neutrophils, coupling of chemoattractants to their cell surface receptor at low temperature (<or=15 degrees C) leads to receptor deactivation/desensitization without any triggering of the superoxide anion-generating NADPH-oxidase. We show that the deactivated formyl peptide receptors (FPRs) can be reactivated/resensitized by the cytoskeleton-disrupting drug cytochalasin B. Such cytoskeleton-dependent receptor reactivation occurs also with the closely related receptors FPR-like-1 and C5aR but not with the receptors for interleukin-8 and platelet-activating factor. The reactivation state was further characterized with FPR as a model. The signals generated by receptor reactivation induced superoxide production that was terminated in 5-8 min, after which the neutrophils entered a new state of homologous deactivation. FPR antagonists were potent inhibitors of the superoxide production induced by the reactivated receptors, suggesting that the occupied receptors turn into an actively signaling state when the cytoskeleton is disrupted. The signals generated by the reactivated receptor were pertussis toxin-sensitive, indicating involvement of a G-protein. However, no transient elevation of intracellular Ca2+ accompanies the NADPH-oxidase activation. This was not due to a general down-regulation of phospholipase C/Ca2+ signaling, and despite the fact that no intracellular Ca2+ transient was generated, protein kinase C still appeared to be involved in the response. Further, phosphatidylinositol 3-kinase, mitogen-activated protein kinase, and MEK all participated in the generation of second messengers from the reactivated receptors.
authors.affiliation: Department of Rheumatology and Inflammation Research, University of Göteborg, Guldhedsgatan 10, S-413 46 Göteborg, Sweden.
authors.forename: Johan
authors.initials: J
authors.lastname: Bylund
authors.forename: Ase
authors.initials: A
authors.lastname: Björstad
authors.forename: Daniel
authors.initials: D
authors.lastname: Granfeldt
authors.forename: Anna
authors.initials: A
authors.lastname: Karlsson
authors.forename: Charlotte
authors.initials: C
authors.lastname: Woschnagg
authors.forename: Claes
authors.initials: C
authors.lastname: Dahlgren
mesh_terms: D000730:Androstadienes / Q000494:pharmacology; D015703:Antigens, CD / Q000737:chemistry / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D003571:Cytochalasin B / Q000494:pharmacology; D003599:Cytoskeleton / Q000187:drug effects / Q000201:enzymology; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000378:metabolism; D018922:HL-60 Cells; D006801:Humans; D019255:NADPH Oxidases / Q000378:metabolism*; D009504:Neutrophils / Q000201:enzymology*; D010980:Platelet Membrane Glycoproteins / Q000737:chemistry / Q000378:metabolism; D017434:Protein Structure, Tertiary; D044087:Receptor, Anaphylatoxin C5a; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000378:metabolism; D011951:Receptors, Complement / Q000737:chemistry / Q000378:metabolism; D044042:Receptors, Formyl Peptide; D043562:Receptors, G-Protein-Coupled; D011971:Receptors, Immunologic / Q000737:chemistry / Q000378:metabolism*; D023062:Receptors, Interleukin-8A / Q000737:chemistry / Q000378:metabolism; D023063:Receptors, Interleukin-8B / Q000737:chemistry / Q000378:metabolism; D018000:Receptors, Peptide / Q000737:chemistry / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D000077191:Wortmannin
chemical_list: D000730:Androstadienes; D015703:Antigens, CD; D004791:Enzyme Inhibitors; D010980:Platelet Membrane Glycoproteins; D044087:Receptor, Anaphylatoxin C5a; D011956:Receptors, Cell Surface; D011951:Receptors, Complement; D044042:Receptors, Formyl Peptide; D043562:Receptors, G-Protein-Coupled; D011971:Receptors, Immunologic; D023062:Receptors, Interleukin-8A; D023063:Receptors, Interleukin-8B; D018000:Receptors, Peptide; C039351:platelet activating factor receptor; D003571:Cytochalasin B; D019255:NADPH Oxidases; D019204:GTP-Binding Proteins; D002118:Calcium; D000077191:Wortmannin