Formyl peptide receptor signaling in HL-60 cells through sphingosine kinase

Sphingosine-1-phosphate (SPP) produced from sphingosine by sphingosine kina se has recently been reported to act as intracellular second messenger for a number of plasma membrane receptors. In the present study, we investigate d whether the sphingosine kinase/SPP pathway is involved in cellular signal ing of the G(i) protein-coupled formyl peptide receptor in myeloid differen tiated human leukemia (HL-60) cells. Receptor activation resulted in rapid and transient production of SPP by sphingosine kinase, which was abolished after pertussis toxin treatment. Direct activation of heterotrimeric G prot eins by AlF4-, also rapidly increased SPP formation in intact HL-60 cells. In cytosolic preparations of HL-60 cells, sphingosine kinase activity was s timulated by the stable GTP analog, guanosine 5'-O-(3-thiotriphosphate). In hibition of sphingosine kinase by DL-threo-dihydrosphingosine and N,N-dimet hylsphingosine did not affect phospholipase C stimulation and superoxide pr oduction but markedly inhibited receptor-stimulated Ca2+ mobilization and e nzyme release. We conclude that the formyl peptide receptor stimulates thro ugh G(i)-type G proteins SPP production by sphingosine kinase, that the enz yme is also stimulated by direct G protein activation, and that the sphingo sine kinase/SPP pathway apparently plays an important role in chemoattracta nt signaling in myeloid differentiated HL-60 cells.