Conserved transducer coupling but different effector linkage upon expression of the myeloid fMet-Leu-Phe receptor in insulin secreting cells.
In neutrophils fMet-Leu-Phe activates phospholipase C via a pertussis toxin sensitive G-protein and induces granule secretion. We have transfected a human cDNA sequence encoding the fMet-Leu-Phe receptor into the insulin secreting cell line RINm5F to study receptor-effector coupling with special regard to secretion. Stable overexpression resulted in membrane hyperpolarization, reduction of cAMP accumulation and inhibition of insulin secretion upon exposure of cells to fMet-Leu-Phe with EC50 values in the pmol range. As in the neutrophil, nanomolar concentrations of ligand induced membrane depolarization and activation of phospholipase C, with subsequent mobilization and influx of calcium. In permeabilized cells the inhibitory effect of fMet-Leu-Phe on secretion was partially retained indicating a direct action of the fMet-Leu-Phe receptor on exocytosis. Pertussis toxin abolished the effects of fMet-Leu-Phe. Our results suggest conserved coupling from fMet-Leu-Phe receptor to pertussis toxin sensitive transducers analogous to the mechanism in neutrophils. However, the net biological effect of receptor activation is determined by additional factors intrinsic to the host cell.
Lang
J
J
Département de Médecine, Université de Genéve, Switzerland.
Boulay
F
F
Li
G
G
Wollheim
C B
CB
D000409:Alanine / Q000494:pharmacology; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism; D004247:DNA; D019204:GTP-Binding Proteins / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D007329:Insulin Antagonists / Q000494:pharmacology; D000078790:Insulin Secretion; D008564:Membrane Potentials / Q000187:drug effects; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000378:metabolism* / Q000494:pharmacology; D037342:Pertussis Toxin; D044042:Receptors, Formyl Peptide; D011971:Receptors, Immunologic / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D014162:Transfection; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D007328:Insulin; D007329:Insulin Antagonists; D044042:Receptors, Formyl Peptide; D011971:Receptors, Immunologic; D010566:Virulence Factors, Bordetella; D009240:N-Formylmethionine Leucyl-Phenylalanine; D004247:DNA; D000242:Cyclic AMP; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins; D000409:Alanine; D002118:Calcium