Novel G protein-coupled responses in leukocytes elicited by a chemotactic bacteriophage displaying a cell type-selective binding peptide.
Recently, we identified a neutrophil-binding phage displaying a novel peptide motif, GPNLTGRW. It was determined that this peptide, when displayed on bacteriophage (FGP phage), elicits a transient increase in cytosolic calcium. Here, we show that FGP phage stimulate neutrophil chemotaxis and induce a pertussis toxin-sensitive rise in cytosolic calcium in monocytes as well as in neutrophils. In contrast to the calcium response elicited by classical chemoattractants fMLP and IL-8, the FGP phage-elicited response in neutrophils is dependent on extracellular calcium and is mediated by receptor-activated, divalent cation channels. Consistent with G protein-coupled receptor signaling, FGP phage effect homologous and reciprocal heterologous desensitization with fMLP- and IL-8-stimulated calcium responses. Like non-G protein-coupled responses, the FGP-elicited calcium transient is abolished with phosphoinositide-3-kinase inactivation. Nonetheless, specific binding of GTP to neutrophil membranes follows stimulation with FGP phage, further supporting involvement of G proteins. However, FGP phage neither bind to nor elicit a calcium response from transfectant cells harboring known candidate G protein-coupled receptors. These data together suggest that the elicited responses are mediated by a novel G protein-coupled receptor or represent novel responses of a known receptor.
Jaye
D L
DL
Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30022, USA. dljaye@emory.edu
Edens
H A
HA
Mazzucchelli
L
L
Parkos
C A
CA
D000818:Animals; D001435:Bacteriophages / Q000276:immunology*; D016466:CHO Cells; D015220:Calcium Channels / Q000378:metabolism; D020013:Calcium Signaling / Q000235:genetics / Q000276:immunology; D002413:Cations, Divalent / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000276:immunology / Q000378:metabolism; D002634:Chemotaxis, Leukocyte / Q000235:genetics; D006224:Cricetinae; D005110:Extracellular Space / Q000502:physiology; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D006801:Humans; D016209:Interleukin-8 / Q000502:physiology; D008214:Lymphocytes / Q000378:metabolism; D051379:Mice; D009000:Monocytes / Q000276:immunology / Q000378:metabolism; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000378:metabolism; D009504:Neutrophils / Q000201:enzymology / Q000276:immunology / Q000378:metabolism; D009842:Oligopeptides / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D019151:Peptide Library; D037342:Pertussis Toxin; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D011485:Protein Binding / Q000235:genetics / Q000276:immunology; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D014162:Transfection; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D015220:Calcium Channels; D002413:Cations, Divalent; D016209:Interleukin-8; D009842:Oligopeptides; D019151:Peptide Library; D011956:Receptors, Cell Surface; D010566:Virulence Factors, Bordetella; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D009240:N-Formylmethionine Leucyl-Phenylalanine; D037342:Pertussis Toxin; D019869:Phosphatidylinositol 3-Kinases; D019204:GTP-Binding Proteins