title: Sphingosine kinase type 1 inhibition reveals rapid turnover of circulating sphingosine 1-phosphate.
abstract: S1P (sphingosine 1-phosphate) is a signalling molecule involved in a host of cellular and physiological functions, most notably cell survival and migration. S1P, which signals via a set of five G-protein-coupled receptors (S1P1-S1P5), is formed by the action of two SphKs (sphingosine kinases) from Sph (sphingosine). Interfering RNA strategies and SphK1 (sphingosine kinase type 1)-null (Sphk1-/-) mouse studies implicate SphK1 in multiple signalling cascades, yet there is a paucity of potent and selective SphK1 inhibitors necessary to evaluate the effects of rapid onset inhibition of this enzyme. We have identified a set of submicromolar amidine-based SphK1 inhibitors and report using a pair of these compounds to probe the cellular and physiological functions of SphK1. In so doing, we demonstrate that our inhibitors effectively lower S1P levels in cell-based assays, but we have been unable to correlate SphK1 inhibition with changes in cell survival. However, SphK1 inhibition did diminish EGF (epidermal growth factor)-driven increases in S1P levels and Akt (also known as protein kinase B)/ERK (extracellular-signal-regulated kinase) phosphorylation. Finally, administration of the SphK1 inhibitor to wild-type, but not Sphk1-/-, mice resulted in a rapid decrease in blood S1P levels indicating that circulating S1P is rapidly turned over.
authors.affiliation: Department of Pharmacology, University of Virginia, 1340 Jefferson Park Avenue, Charlottesville, VA 22908, USA.
authors.forename: Yugesh
authors.initials: Y
authors.lastname: Kharel
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Mathews
authors.forename: Amanda M
authors.initials: AM
authors.lastname: Gellett
authors.forename: Jose L
authors.initials: JL
authors.lastname: Tomsig
authors.forename: Perry C
authors.initials: PC
authors.lastname: Kennedy
authors.forename: Morgan L
authors.initials: ML
authors.lastname: Moyer
authors.forename: Timothy L
authors.initials: TL
authors.lastname: Macdonald
authors.forename: Kevin R
authors.initials: KR
authors.lastname: Lynch
mesh_terms: D000578:Amidines / Q000493:pharmacokinetics / Q000494:pharmacology*; D000818:Animals; D053148:Caspase 3 / Q000378:metabolism; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D006801:Humans; D008246:Lysophospholipids / Q000097:blood / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D010766:Phosphorylation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000037:antagonists & inhibitors*; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011759:Pyrrolidines / Q000493:pharmacokinetics / Q000494:pharmacology*; D051381:Rats; D013107:Sphingolipids / Q000378:metabolism; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000097:blood / Q000378:metabolism; D013237:Stereoisomerism; D000099157:Sphingosine Kinase
chemical_list: D000578:Amidines; D053148:Caspase 3; D048049:Extracellular Signal-Regulated MAP Kinases; D008246:Lysophospholipids; D017853:Phosphotransferases (Alcohol Group Acceptor); D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D051057:Proto-Oncogene Proteins c-akt; D011759:Pyrrolidines; D013107:Sphingolipids; D013110:Sphingosine; D000099157:Sphingosine Kinase; C060506:sphingosine 1-phosphate; C499320:PARP1 protein, human; C505407:CASP3 protein, human