Role of sphingosine-1-phosphate phosphatase 1 in epidermal growth factor-induced chemotaxis.
Sphingosine-1-phosphate (S1P) is the ligand for a family of specific G protein-coupled receptors that regulate a wide variety of cellular functions, including cytoskeletal rearrangements and cell motility. Because of the pivotal role of S1P, its levels are low and tightly regulated in a spatial-temporal manner through its synthesis catalyzed by sphingosine kinases and degradation by an S1P lyase and specific S1P phosphatases (SPP). Surprisingly, down-regulation of SPP-1 enhanced migration toward epidermal growth factor (EGF); conversely, overexpression of SPP-1, which is localized in the endoplasmic reticulum, attenuated migration toward EGF. To determine whether the inhibitory effect on EGF-induced migration was because of decreased S1P or increased ceramide as a consequence of acylation of increased sphingosine by ceramide synthase, we used fumonisin B1, a specific inhibitor of ceramide synthase. Although fumonisin B1 blocked ceramide production and increased sphingosine, it did not reverse the negative effect of SPP-1 expression on EGF- or S1P-induced chemotaxis. EGF activated the epidermal growth factor receptor to the same extent in SPP-1-expressing cells, yet ERK1/2 activation was impaired. In agreement, PD98059, an inhibitor of the ERK-activating enzyme MEK, decreased EGF-stimulated migration. We next examined the possibility that intracellularly generated S1P might be involved in activating a G protein-coupled S1P receptor important for EGF-directed migration. Treatment with pertussis toxin to inactivate Galpha(i) suppressed EGF-induced migration. Moreover, expression of regulator of G protein signaling 3, which inhibits S1P receptor signaling and completely prevented ERK1/2 activation mediated by S1P receptors, not only reduced migration toward S1P but also markedly reduced migration toward EGF. Collectively, these results suggest that metabolism of S1P by SPP-1 is important for EGF-directed cell migration.
Le Stunff
Hervé
H
Department of Biochemistry, Virginia Commonwealth University School of Medicine, Richmond, VA 23298, USA.
Mikami
Aki
A
Giussani
Paola
P
Hobson
John P
JP
Jolly
Puneet S
PS
Milstien
Sheldon
S
Spiegel
Sarah
S
D015153:Blotting, Western; D002460:Cell Line; D002465:Cell Movement; D002518:Ceramides / Q000378:metabolism; D002633:Chemotaxis; D002855:Chromatography, Thin Layer; D015536:Down-Regulation; D004591:Electrophoresis, Polyacrylamide Gel; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004815:Epidermal Growth Factor / Q000378:metabolism*; D066246:ErbB Receptors / Q000378:metabolism; D005419:Flavonoids / Q000494:pharmacology; D037341:Fumonisins / Q000494:pharmacology; D005822:Genetic Vectors; D006801:Humans; D006868:Hydrolysis; D008565:Membrane Proteins / Q000502:physiology*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010088:Oxidoreductases / Q000378:metabolism; D037342:Pertussis Toxin / Q000494:pharmacology; D010744:Phosphoric Monoester Hydrolases / Q000502:physiology*; D011233:Precipitin Tests; D034741:RNA, Small Interfering / Q000378:metabolism; D015398:Signal Transduction; D013997:Time Factors; D014162:Transfection
D002518:Ceramides; D004791:Enzyme Inhibitors; D005419:Flavonoids; D037341:Fumonisins; D008565:Membrane Proteins; D034741:RNA, Small Interfering; C056933:fumonisin B1; D004815:Epidermal Growth Factor; D010088:Oxidoreductases; C108138:dihydroceramide desaturase; D037342:Pertussis Toxin; D066246:ErbB Receptors; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; C498527:SGPP1 protein, human; C401298:sphingosine-1-phosphate phosphatase; D010744:Phosphoric Monoester Hydrolases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one