The FPR2-specific ligand MMK-1 activates the neutrophil NADPH-oxidase, but triggers no unique pathway for opening of plasma membrane calcium channels.
Human neutrophils express formyl peptide receptor 1 and 2 (FPR1 and FPR2), two highly homologous G-protein-coupled cell surface receptors important for the cellular recognition of chemotactic peptides. They share many functional as well as signal transduction features, but some fundamental differences have been described. One such difference was recently presented when the FPR2-specific ligand MMK-1 was shown to trigger a unique signal in neutrophils [S. Partida-Sanchez, P. Iribarren, M.E. Moreno-Garcia, et al., Chemotaxis and calcium responses of phagocytes to formyl peptide receptor ligands is differentially regulated by cyclic ADP ribose, J. Immunol. 172 (2004) 1896-1906]. This signal bypassed the emptying of the intracellular calcium stores, a route normally used to open the store-operated calcium channels present in the plasma membrane of neutrophils. Instead, the binding of MMK-1 to FPR2 was shown to trigger a direct opening of the plasma membrane channels. In this report, we add MMK-1 to a large number of FPR2 ligands that activate the neutrophil superoxide-generating NADPH-oxidase. In contrast to earlier findings we show that the transient rise in intracellular free calcium induced by MMK-1 involves both a release of calcium from intracellular stores and an opening of channels in the plasma membrane. The same pattern was obtained with another characterized FPR2 ligand, WKYMVM, and it is also obvious that the two formyl peptide receptor family members trigger the same type of calcium response in human neutrophils.
Karlsson
Jennie
J
Department of Rheumatology and Inflammation Research, University of Gothenburg, Sweden. jennie.karlsson@rheuma.gu.se
Stenfeldt
Anna-Lena
AL
Rabiet
Marie-Josèphe
MJ
Bylund
Johan
J
Forsman
Huamei Fu
HF
Dahlgren
Claes
C
D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D004789:Enzyme Activation; D018922:HL-60 Cells; D006801:Humans; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000378:metabolism; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism*; D009504:Neutrophils / Q000166:cytology / Q000378:metabolism*; D010455:Peptides / Q000235:genetics / Q000378:metabolism*; D044042:Receptors, Formyl Peptide / Q000235:genetics / Q000378:metabolism*; D044067:Receptors, Lipoxin / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D013481:Superoxides / Q000378:metabolism
D015220:Calcium Channels; C105101:FPR2 protein, human; C408903:MMK-1 peptide; D010455:Peptides; D044042:Receptors, Formyl Peptide; D044067:Receptors, Lipoxin; D013481:Superoxides; D009240:N-Formylmethionine Leucyl-Phenylalanine; D019255:NADPH Oxidases; D002118:Calcium