EDG-1 links the PDGF receptor to Src and focal adhesion kinase activation leading to lamellipodia formation and cell migration.
Sphingosine-1-phosphate (SPP), formed by sphingosine kinase, is the ligand for EDG-1, a GPCR important for cell migration and vascular maturation. Here we show that cytoskeletal rearrangements, lamellipodia extensions, and cell motility induced by platelet-derived growth factor (PDGF) are abrogated in EDG-1 null fibroblasts. However, EDG-1 appears to be dispensable for mitogenicity and survival effects, even those induced by its ligand SPP and by PDGF. Furthermore, PDGF induced focal adhesion formation and activation of FAK, Src, and stress-activated protein kinase 2, p38, were dysregulated in the absence of EDG-1. In contrast, tyrosine phosphorylation of the PDGFR and activation of extracellular signal regulated kinase (ERK1/2), important for growth and survival, were unaltered. Our results suggest that EDG-1 functions as an integrator linking the PDGFR to lamellipodia extension and cell migration. PDGF, which stimulates sphingosine kinase, leading to increased SPP levels in many cell types, also induces translocation of sphingosine kinase to membrane ruffles. Hence, recruitment of sphingosine kinase to the cell's leading edge and localized formation of SPP may spatially and temporally stimulate EDG-1, resulting in activation and integration of downstream signals important for directional movement toward chemoattractants, such as PDGF. These results may also shed light on the vital role of EDG-1 in vascular maturation.
Rosenfeldt
H M
HM
Department of Biochemistry and Molecular Biology, Georgetown University Medical Center, Washington, D.C. 20007, USA.
Hobson
J P
JP
Maceyka
M
M
Olivera
A
A
Nava
V E
VE
Milstien
S
S
Spiegel
S
S
D016475:3T3 Cells; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001692:Biological Transport / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002465:Cell Movement / Q000502:physiology*; D002478:Cells, Cultured; D002633:Chemotaxis / Q000187:drug effects; D003599:Cytoskeleton / Q000187:drug effects; D004247:DNA / Q000096:biosynthesis / Q000187:drug effects; D004622:Embryo, Mammalian / Q000166:cytology / Q000378:metabolism; D004789:Enzyme Activation; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D005838:Genotype; D049452:Green Fluorescent Proteins; D017874:Immediate-Early Proteins / Q000235:genetics / Q000502:physiology*; D008164:Luminescent Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D008246:Lysophospholipids; D051379:Mice; D018345:Mice, Knockout; D018613:Microscopy, Confocal; D010766:Phosphorylation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011554:Pseudopodia / Q000502:physiology*; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; D049312:Receptors, Lysophospholipid; D017479:Receptors, Platelet-Derived Growth Factor / Q000378:metabolism* / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D013997:Time Factors; D019061:src-Family Kinases / Q000378:metabolism*; D000099157:Sphingosine Kinase
D004247:DNA; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D049452:Green Fluorescent Proteins; D017874:Immediate-Early Proteins; D008164:Luminescent Proteins; D008246:Lysophospholipids; D017853:Phosphotransferases (Alcohol Group Acceptor); D010982:Platelet-Derived Growth Factor; D011505:Protein-Tyrosine Kinases; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; D049312:Receptors, Lysophospholipid; D017479:Receptors, Platelet-Derived Growth Factor; D011993:Recombinant Fusion Proteins; D013110:Sphingosine; D019061:src-Family Kinases; D000099157:Sphingosine Kinase; C060506:sphingosine 1-phosphate; C496051:Ptk2 protein, mouse